Rhythmic, intermittent propagation of a fluid through a BLOOD VESSEL or piping system, in contrast to constant, smooth propagation, which produces laminar flow.
A value equal to the total volume flow divided by the cross-sectional area of the vascular bed.
Theoretical representations that simulate the behavior or activity of the cardiovascular system, processes, or phenomena; includes the use of mathematical equations, computers and other electronic equipment.
Methods of preparing tissue specimens for visualization using an electron microscope, usually a scanning electron microscope. The methods involve the creation of exact copies of the specimens by making a mold or cast (i.e., replica) of the specimen.
The flow of BLOOD through or around an organ or region of the body.
The study of the deformation and flow of matter, usually liquids or fluids, and of the plastic flow of solids. The concept covers consistency, dilatancy, liquefaction, resistance to flow, shearing, thixotrophy, and VISCOSITY.
The deformation and flow behavior of BLOOD and its elements i.e., PLASMA; ERYTHROCYTES; WHITE BLOOD CELLS; and BLOOD PLATELETS.
A purely physical condition which exists within any material because of strain or deformation by external forces or by non-uniform thermal expansion; expressed quantitatively in units of force per unit area.
Three-dimensional representation to show anatomic structures. Models may be used in place of intact animals or organisms for teaching, practice, and study.
The internal resistance of a material to moving some parts of it parallel to a fixed plane, in contrast to stretching (TENSILE STRENGTH) or compression (COMPRESSIVE STRENGTH). Ionic crystals are brittle because, when subjected to shear, ions of the same charge are brought next to each other, which causes repulsion.
Unique slender cells with multiple processes extending along the capillary vessel axis and encircling the vascular wall, also called mural cells. Pericytes are imbedded in the BASEMENT MEMBRANE shared with the ENDOTHELIAL CELLS of the vessel. Pericytes are important in maintaining vessel integrity, angiogenesis, and vascular remodeling.
Methods of creating machines and devices.
Ultrasonography applying the Doppler effect, with the superposition of flow information as colors on a gray scale in a real-time image. This type of ultrasonography is well-suited to identifying the location of high-velocity flow (such as in a stenosis) or of mapping the extent of flow in a certain region.
Technique using an instrument system for making, processing, and displaying one or more measurements on individual cells obtained from a cell suspension. Cells are usually stained with one or more fluorescent dyes specific to cell components of interest, e.g., DNA, and fluorescence of each cell is measured as it rapidly transverses the excitation beam (laser or mercury arc lamp). Fluorescence provides a quantitative measure of various biochemical and biophysical properties of the cell, as well as a basis for cell sorting. Other measurable optical parameters include light absorption and light scattering, the latter being applicable to the measurement of cell size, shape, density, granularity, and stain uptake.
The vessels carrying blood away from the capillary beds.
Devices or objects in various imaging techniques used to visualize or enhance visualization by simulating conditions encountered in the procedure. Phantoms are used very often in procedures employing or measuring x-irradiation or radioactive material to evaluate performance. Phantoms often have properties similar to human tissue. Water demonstrates absorbing properties similar to normal tissue, hence water-filled phantoms are used to map radiation levels. Phantoms are used also as teaching aids to simulate real conditions with x-ray or ultrasonic machines. (From Iturralde, Dictionary and Handbook of Nuclear Medicine and Clinical Imaging, 1990)
Small pumps, often implantable, designed for temporarily assisting the heart, usually the LEFT VENTRICLE, to pump blood. They consist of a pumping chamber and a power source, which may be partially or totally external to the body and activated by electromagnetic motors.
The circulation of the BLOOD through the LUNGS.
Echocardiography applying the Doppler effect, with the superposition of flow information as colors on a gray scale in a real-time image.
The circulation of blood through the CORONARY VESSELS of the HEART.
PRESSURE of the BLOOD on the ARTERIES and other BLOOD VESSELS.
The movement and the forces involved in the movement of the blood through the CARDIOVASCULAR SYSTEM.
A type of stress exerted uniformly in all directions. Its measure is the force exerted per unit area. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
Device constructed of either synthetic or biological material that is used for the repair of injured or diseased blood vessels.
Any of the tubular vessels conveying the blood (arteries, arterioles, capillaries, venules, and veins).
The main artery of the thigh, a continuation of the external iliac artery.
Either of the two principal arteries on both sides of the neck that supply blood to the head and neck; each divides into two branches, the internal carotid artery and the external carotid artery.
A device that substitutes for a heart valve. It may be composed of biological material (BIOPROSTHESIS) and/or synthetic material.
Treatment process involving the injection of fluid into an organ or tissue.
Abnormal outpouching in the wall of intracranial blood vessels. Most common are the saccular (berry) aneurysms located at branch points in CIRCLE OF WILLIS at the base of the brain. Vessel rupture results in SUBARACHNOID HEMORRHAGE or INTRACRANIAL HEMORRHAGES. Giant aneurysms (>2.5 cm in diameter) may compress adjacent structures, including the OCULOMOTOR NERVE. (From Adams et al., Principles of Neurology, 6th ed, p841)
The vessels carrying blood away from the heart.
The testing of materials and devices, especially those used for PROSTHESES AND IMPLANTS; SUTURES; TISSUE ADHESIVES; etc., for hardness, strength, durability, safety, efficacy, and biocompatibility.
Single pavement layer of cells which line the luminal surface of the entire vascular system and regulate the transport of macromolecules and blood components.
Computer-based representation of physical systems and phenomena such as chemical processes.
The plan and delineation of prostheses in general or a specific prosthesis.
A CALCIUM-dependent, constitutively-expressed form of nitric oxide synthase found primarily in ENDOTHELIAL CELLS.
Elements of limited time intervals, contributing to particular results or situations.
The veins and arteries of the HEART.
The main trunk of the systemic arteries.
The properties, processes, and behavior of biological systems under the action of mechanical forces.
The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.
Any of various animals that constitute the family Suidae and comprise stout-bodied, short-legged omnivorous mammals with thick skin, usually covered with coarse bristles, a rather long mobile snout, and small tail. Included are the genera Babyrousa, Phacochoerus (wart hogs), and Sus, the latter containing the domestic pig (see SUS SCROFA).
The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)
The change in gene frequency in a population due to migration of gametes or individuals (ANIMAL MIGRATION) across population barriers. In contrast, in GENETIC DRIFT the cause of gene frequency changes are not a result of population or gamete movement.
Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.
Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.
Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.
The application of knowledge to the food industry.
The edible portions of any animal used for food including domestic mammals (the major ones being cattle, swine, and sheep) along with poultry, fish, shellfish, and game.
Physiological changes that occur in bodies after death.
Dissertations embodying results of original research and especially substantiating a specific view, e.g., substantial papers written by candidates for an academic degree under the individual direction of a professor or papers written by undergraduates desirous of achieving honors or distinction.
Information application based on a variety of coding methods to minimize the amount of data to be stored, retrieved, or transmitted. Data compression can be applied to various forms of data, such as images and signals. It is used to reduce costs and increase efficiency in the maintenance of large volumes of data.
Non-invasive method of demonstrating internal anatomy based on the principle that atomic nuclei in a strong magnetic field absorb pulses of radiofrequency energy and emit them as radiowaves which can be reconstructed into computerized images. The concept includes proton spin tomographic techniques.
Non-invasive method of vascular imaging and determination of internal anatomy without injection of contrast media or radiation exposure. The technique is used especially in CEREBRAL ANGIOGRAPHY as well as for studies of other vascular structures.
The arterial blood vessels supplying the CEREBRUM.

Pulsatile shear stress leads to DNA fragmentation in human SH-SY5Y neuroblastoma cell line. (1/1458)

1. Using an in vitro model of shear stress-induced cell injury we demonstrate that application of shear to differentiated human SH-SY5Y cells leads to cell death characterized by DNA fragmentation. Controlled shear stress was applied to cells via a modified cone and plate viscometer. 2. We show that pulsatile shear stress leads to DNA fragmentation, as determined via flow cytometry of fluorescein-12-dUTP nick-end labelled cells, in 45 +/- 4 % of cells. No lactate dehydrogenase (LDH) release was observed immediately after injury; however, 24 h after injury significant LDH release was observed. 3. Nitric oxide production by cells subjected to pulsatile shear increased two- to threefold over that in unsheared control cells. 4. Inhibition of protein synthesis, nitric oxide production, Ca2+ entry into cells, and pertussis toxin-sensitive G protein activation attenuated the shear stress-induced cell injury. 5. Our results show for the first time that application of pulsatile shear stress to a neuron-like cell in vitro leads to nitric oxide-dependent cell death.  (+info)

Independent prognostic information provided by sphygmomanometrically determined pulse pressure and mean arterial pressure in patients with left ventricular dysfunction. (2/1458)

OBJECTIVES: The purpose of this study was to evaluate the relationship of baseline pulse pressure and mean arterial pressure to mortality in patients with left ventricular dysfunction. BACKGROUND: Increased conduit vessel stiffness increases pulse pressure and pulsatile load, potentially contributing to adverse outcomes in patients with left ventricular dysfunction. METHODS: Pulse and mean arterial pressure were analyzed for their effect on mortality, adjusting for other modifiers of risk, using Cox proportional hazards regression analysis of data collected from 6,781 patients randomized into the Studies of Left Ventricular Dysfunction trials. RESULTS: Pulse and mean arterial pressure were related positively to each other, age, ejection fraction and prevalence of diabetes and hypertension and inversely to prior myocardial infarction and beta-adrenergic blocking agent use. Higher pulse pressure was associated with increased prevalence of female gender, greater calcium channel blocking agent, digoxin and diuretic use, lower heart rate and a higher rate of reported smoking history. Higher mean arterial pressure was associated with higher heart rate, lower calcium channel blocker and digoxin use and lower New York Heart Association functional class. Over a 61-month follow-up 1,582 deaths (1,397 cardiovascular) occurred. In a multivariate analysis adjusting for the above covariates and treatment assignment, higher pulse pressure remained an independent predictor of total and cardiovascular mortality (total mortality relative risk, 1.05 per 10 mm Hg increment; 95% confidence interval, 1.01 to 1.10; p = 0.02). Mean arterial pressure was inversely related to total and cardiovascular mortality (total mortality relative risk, 0.89; 95% confidence interval, 0.85 to 0.94; p <0.0001). CONCLUSIONS: One noninvasive blood pressure measurement provides two independent prognostic factors for survival. Increased conduit vessel stiffness, as assessed by pulse pressure, may contribute to increased mortality in patients with left ventricular dysfunction, independent of mean arterial pressure.  (+info)

In vitro and in vivo comparison of three MR measurement methods for calculating vascular shear stress in the internal carotid artery. (3/1458)

BACKGROUND AND PURPOSE: Vascular abnormalities, such as atherosclerosis and the growth and rupture of cerebral aneurysms, result from a derangement in tissue metabolism and injury that are, in part, regulated by hemodynamic stress. The purpose of this study was to establish the feasibility and accuracy of determining wall shear rate in the internal carotid artery from phase-contrast MR data. METHODS: Three algorithms were used to generate shear rate estimates from both ungated and cardiac-gated 2D phase-contrast data. These algorithms were linear extrapolation (LE), linear estimation with correction for wall position (LE*), and quadratic extrapolation (QE). In vitro experiments were conducted by using a phantom under conditions of both nonpulsatile and pulsatile flow. The findings from five healthy volunteers were also studied. MR imaging-derived shear rates were compared with values calculated by solving the fluid flow equations. RESULTS: Findings of in vitro constant-flow experiments indicated that at one or two excitations, QE has the advantage of good accuracy and low variance. Results of in vitro pulsatile flow experiments showed that neither LE* nor QE differed significantly from the predicted value of wall shear stress, despite errors of 17% and 22%, respectively. In vivo data showed that QE did not differ significantly from the predicted value, whereas LE and LE* did. The percentages of errors for QE, LE, and LE* in vivo measurements were 98.5%, 28.5%, and 36.1%, respectively. The average residual of QE was low because the residuals were both above and below baseline whereas, on average, LE* tended to be a more biased overestimator of the shear rate in volunteers. The average and peak wall shear force in five volunteers was approximately 8.10 dyne/cm2 and 13.2 dyne/cm2, respectively. CONCLUSION: Our findings show that LE consistently underestimates the shear rate. Although LE* and QE may be used to estimate shear rate, errors of up to 36% should be expected because of variance above and below the true value for individual measurements.  (+info)

The pattern of changes in ovarian stromal and uterine artery blood flow velocities during in vitro fertilization treatment and its relationship with outcome of the cycle. (4/1458)

OBJECTIVES: To assess the effect of short-term (2-3 weeks) pituitary suppression and controlled ovarian stimulation on ovarian and uterine artery Doppler measurements during the in vitro fertilization (IVF) treatment cycle and to compare the pattern of these changes between conception and non-conception cycles as well as between patients with normal and those with polycystic ovaries. DESIGN: Prospective observational study of women undergoing IVF treatment. SUBJECTS: Women using the long-treatment buserelin protocol who did not have uterine fibroids, ovarian cysts or endometrioma. METHODS: Serial transvaginal color and pulsed Doppler measurements of ovarian stromal and uterine artery blood flow velocity were carried out in the early follicular phase of the menstrual cycle, on the day of pituitary suppression and on the day of administration of human chorionic gonadotropin (hCG). The main outcome measures were the ovarian stromal and uterine artery blood flow peak systolic velocity (PSV) and pulsatility index (PI). RESULTS: A total of 105 patients were recruited but six patients were excluded from the analysis because they had only one stage of the measurements performed. There was a significant decline in mean ovarian stromal artery PSV after 2-3 weeks of gonadotropin releasing hormone (GnRH) agonist therapy but no effect on ovarian stromal artery PI. The mean uterine artery PSV or PI did not change significantly after 2-3 weeks of GnRH agonist therapy. There was a significantly higher mean ovarian stromal artery PSV in conception cycles compared to non-conception cycles in the early follicular phase and on the day of pituitary suppression, but not on the day of hCG administration. There were no differences between conception and non-conception cycles in the mean uterine artery PSV or PI. Women with polycystic ovaries had a higher mean ovarian artery PSV on all the three occasions of measurement. CONCLUSION: These data suggest that assessment of ovarian blood flow before commencement of gonadotropin stimulation may play a role in assessing cycles likely to result in pregnancy.  (+info)

Characteristics of blood flow in intrauterine growth-restricted fetuses with hypercoiled cord. (5/1458)

OBJECTIVE: To clarify the characteristics of fetoplacental blood flow of growth-restricted fetuses with hypercoiled umbilical cord. SUBJECTS: Eight growth-restricted fetuses with hypercoiled cord. METHODS: Flow velocity waveforms of the umbilical cord artery and vein, fetal abdominal aorta and fetal inferior vena cava were analyzed. RESULTS: The resistance index in the umbilical artery in the hypercoiled cases was lower than that in normal fetuses. Early-diastolic reversed flow was observed in the abdominal aorta in some cases. In all cases, umbilical venous pulsation was observed in the entire cord until delivery. In one case, fetal heart failure occurred, resulting in pre-mature delivery. An atrophic type of single umbilical artery was observed in four cases. CONCLUSION: Fetal blood flow disturbance caused by a hypercoiled umbilical cord may be a cause of growth restriction.  (+info)

Pulmonary and caval flow dynamics after total cavopulmonary connection. (6/1458)

OBJECTIVE: To assess flow dynamics after total cavopulmonary connection (TCPC). DESIGN: Cross-sectional study. SETTING: Aarhus University Hospital. PATIENTS: Seven patients (mean age 9 (4-18) years) who had previously undergone a lateral tunnel TCPC mean 2 (0. 3-5) years earlier. INTERVENTIONS: Pressure recordings (cardiac catheterisation), flow volume, and temporal changes of flow in the lateral tunnel, superior vena cava, and right and left pulmonary arteries (magnetic resonance velocity mapping). RESULTS: Superior vena cava flow was similar to lateral tunnel flow (1.7 (0.6-1.9) v 1. 3 (0.9-2.4) l/min*m2) (NS), and right pulmonary artery flow was higher than left pulmonary artery flow (1.7 (0.6-4.3) v 1.1 (0.8-2. 5) l/min*m2, p < 0.05). The flow pulsatility index was highest in the lateral tunnel (2.0 (1.1-8.5)), lowest in the superior vena cava (0.8 (0.5-2.4)), and intermediate in the left and right pulmonary arteries (1.6 (0.9-2.0) and 1.2 (0.4-1.9), respectively). Flow and pressure waveforms were biphasic with maxima in atrial systole and late ventricular systole. CONCLUSIONS: Following a standard lateral tunnel TCPC, flow returning via the superior vena cava is not lower than flow returning via the inferior vena cava as otherwise seen in healthy subjects; flow distribution to the pulmonary arteries is optimal; and some pulsatility is preserved primarily in the lateral tunnel and the corresponding pulmonary artery. This study provides in vivo data for future in vitro and computer model studies.  (+info)

The effect of cold stress on uterine artery blood flow velocity waveforms in late pregnant women with and without preeclampsia. (7/1458)

Cold stimulus, immersing the hand into ice water, was given to pregnant women with and without preeclampsia. The uterine artery blood flow was observed before, during and after the stimulus by Doppler ultrasound. The pulsatility index in the uterine artery blood flow was significantly increased by the cold exposure in preeclampsia from 1.14 to 1.52, whereas it increased in normal control from 0.95 to 1.25. In two of 11 cases of preeclampsia with fetal growth restriction, cold stimulus to the mother elicited a decrease of variability on fetal heart rate monitoring. Cold stimulus induces the constriction of the uterine artery, leading to a decrease of placental blood flow.  (+info)

Transcranial color-coded duplex sonography of intracranial veins and sinuses in adults. Reference data from 130 volunteers. (8/1458)

BACKGROUND AND PURPOSE: Transcranial color-coded duplex sonography (TCCS) of intracranial veins and sinuses in adults is a new, emerging application of ultrasonographic imaging. This study reports a standardized examination protocol for venous TCCS and provides reference data for clinical application. METHODS: In 130 healthy volunteers (mean age, 45.9+/-16.9 years; range, 14 to 77 years) the intracranial venous system was examined using frequency-based transtemporal TCCS. Identification rate, blood flow velocity, resistance index, and systolic/diastolic ratio were recorded for each examined venous vessel. RESULTS: Intracranial veins and sinuses show a low pulsatile forward flow with maximal systolic blood flow velocity up to 20 cm/s. Significant side differences of blood flow velocity in the paired venous structures could not be detected. Venous flow velocities decreased with age, whereas resistance indices and systolic/diastolic ratios increased. Women showed higher flow velocities than men. Mean identification rates for all age groups ranged from 70% to 90% for the deep middle cerebral vein, the basal cerebral vein, and the great cerebral vein of Galen. The straight sinus, the transverse sinus, and the rostral part of the superior sagittal sinus could be detected in 55% to 70% of cases. Detection rates were dependent on age and decreased as age increased. CONCLUSIONS: Venous TCCS can reliably image a significant part of the cerebral venous system. This method can provide information on venous hemodynamics in normal subjects and pathological cases.  (+info)

TY - JOUR. T1 - Piezoelectric sensor determination of arterial pulse wave velocity. AU - McLaughlin, JAD. AU - McNeill, MDJ. AU - Braun, B. AU - McCormack, PD. PY - 2003. Y1 - 2003. N2 - Arterial pulse wave velocity (APWV) is a measure of the elasticity (or stiffness) of peripheral arterial blood vessels. The pulse referred to here will be the pressure pulse as opposed to the flow pulse measured by ultrasound Doppler. The pressure pulse velocity varies over the range from about 12 m s−1 to 15 m s−1 in stiff peripheral arteries, whereas in normal arteries it has a velocity in the range of 7 to 9 m s−1.The aim of this project was the development of a fast and easy to use system for the determination of peripheral arterial pulse wave velocity. The principle of the PWV measurement is based on simultaneous measurement of two pulse waves at two different positions, such as the radial artery at the wrist and the brachial artery just above the elbow. By determining the pulse transit time between ...
Purpose: : To determine the effect of panretinal photocoagulation (PRP) on the pulsatile ocular blood flow (POBF) and the pulse amplitude (PA) in patients with proliferative diabetic retinopathy (PDR). Methods: : Twelve eyes of 12 patients with PDR who had undergone PRP were included. The POBF and the PA were measured with Langham OBF computerized tonometry system before, 1 month and 6 month after the last photocoagulation. Results: : The mean POBF and PA significantly (p,0.05) decreased 1 month (589.8 +/- 74.1 microlit/min and 1.26 +/- 0.23 mmHg) and 6 months (563.39 +/- 51.7 microlit/min and 1.08 +/- 0.10 mmHg) after PRP compared with those (770.2 +/- 90.2 microlit /min and 1.61 +/- 0.24 mmHg) before PRP. Conclusions: : This is the first study to examine the effect of PRP on pulsatile ocular blood flow using the Langham tonometer in patients with PDR. The present results that the mean PA and POBF decrease after PRP indicate that total choroidal blood flow may decrease in response to PRP. ...
Phase contrast MRI has been used to investigate flow pulsatility in cerebral arteries, larger cerebral veins and the cerebrospinal fluid. Such measurements of intracranial pulsatility and compliance are beginning to inform understanding of the pathophysiology of conditions including normal pressure hydrocephalus, multiple sclerosis and dementias. We demonstrate the presence of flow pulsatility in small cerebral cortical veins, for the first time using phase contrast MRI at 7 Tesla, with the aim of improving our understanding of the haemodynamics of this little-studied vascular compartment. An automated method for establishing where venous flow is pulsatile is introduced, revealing significant pulsatility in 116 out of 146 veins, across 8 healthy participants, assessed in parietal and frontal regions. Distributions of pulsatility index and pulse waveform delay were characterized, indicating a small, but statistically significant (p,0.05), delay of 59±41 ms in cortical veins with respect to the ...
We have shown a significant effect of smoking on large-artery properties. Acutely, cigarette smoking increased the AIx and PWV, suggesting an increase in arterial stiffness. Perhaps the most interesting finding was that young, otherwise healthy smokers have higher aortic systolic pressure and AIx compared with nonsmokers as the result of increased arterial wave reflection in the aorta, suggesting stiffer arteries. Decreased elasticity of such arteries is also suggested by the reduced pulse pressure amplification in chronic smokers.. The effect of acute cigarette smoking in healthy nonsmokers on forearm arterial hemodynamics showed an increase in BP, heart rate, and PWV.16 Acute cigarette smoking decreased arterial compliance in both large elastic and medium-sized muscular arteries.3,17 More recently, Stefanadis et al,5 using invasive methods, showed decreased aortic compliance acutely after smoking 1 cigarette in middle-aged men with coronary artery disease.. In the current study, AIx was ...
Arterial pulse wave velocity (PWV) is associated with increased mortality in aging and disease. Several studies have shown the accuracy of applanation tonometry carotid-femoral PWV (Cf-PWV) and the relevance of evaluating central aorta stiffness using 2D cardiovascular magnetic resonance (CMR) to estimate PWV, and aortic distensibility-derived PWV through the theoretical Bramwell-Hill model (BH-PWV). Our aim was to compare various methods of aortic PWV (aoPWV) estimation from 4D flow CMR, in terms of associations with age, Cf-PWV, BH-PWV and left ventricular (LV) mass-to-volume ratio while evaluating inter-observer reproducibility and robustness to temporal resolution. We studied 47 healthy subjects (49.5 ± 18 years) who underwent Cf-PWV and CMR including aortic 4D flow CMR as well as 2D cine SSFP for BH-PWV and LV mass-to-volume ratio estimation. The aorta was semi-automatically segmented from 4D flow data, and mean velocity waveforms were estimated in 25 planes perpendicular to the aortic centerline.
TY - GEN. T1 - Effect of pulsatile flow on the Albumin permeability across the endothelial cell layer. AU - Kawarabayashi, Minoru. AU - Ikeda, Mariko. AU - Tanishita, Kazuo. PY - 2001. Y1 - 2001. N2 - The effect of pulsatile flow on the albumin permeability across the endothelial cell layer was discussed. The morphology and functions of the cells were affected by the external mechanical stimulus. It was found that the pulsation promoted the different mechano-transduction process from that of the steady flow.. AB - The effect of pulsatile flow on the albumin permeability across the endothelial cell layer was discussed. The morphology and functions of the cells were affected by the external mechanical stimulus. It was found that the pulsation promoted the different mechano-transduction process from that of the steady flow.. UR - http://www.scopus.com/inward/record.url?scp=0242693884&partnerID=8YFLogxK. UR - http://www.scopus.com/inward/citedby.url?scp=0242693884&partnerID=8YFLogxK. M3 - Conference ...
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Total cavopulmonary connection is the result of a series of palliative surgical repairs performed on patients with single ventricle heart defects. The resulting anatomy has complex and unsteady hemodynamics characterized by flow mixing and flow separation. Although varying degrees of flow pulsatility have been observed in vivo, non-pulsatile (time-averaged) boundary conditions have traditionally been assumed in hemodynamic modeling, and only recently have pulsatile conditions been incorporated without completely characterizing their effect or importance. In this study, 3D numerical simulations with both pulsatile and non-pulsatile boundary conditions were performed for 24 patients with different anatomies and flow boundary conditions from Georgia Tech database. Flow structures, energy dissipation rates and pressure drops were compared under rest and simulated exercise conditions. It was found that flow pulsatility is the primary factor in determining the appropriate choice of boundary ...
Total cavopulmonary connection is the result of a series of palliative surgical repairs performed on patients with single ventricle heart defects. The resulting anatomy has complex and unsteady hemodynamics characterized by flow mixing and flow separation. Although varying degrees of flow pulsatility have been observed in vivo, non-pulsatile (time-averaged) boundary conditions have traditionally been assumed in hemodynamic modeling, and only recently have pulsatile conditions been incorporated without completely characterizing their effect or importance. In this study, 3D numerical simulations with both pulsatile and non-pulsatile boundary conditions were performed for 24 patients with different anatomies and flow boundary conditions from Georgia Tech database. Flow structures, energy dissipation rates and pressure drops were compared under rest and simulated exercise conditions. It was found that flow pulsatility is the primary factor in determining the appropriate choice of boundary ...
INTRODUCTION: Increased aortic stiffness is correlated with many clinically adverse cardiovascular outcomes. The gold standard quantitative index for arterial stiffness is the pulse wave velocity (PWV). We have developed a new method called the Intrinsic Frequency (IF), which views the arterial pressure waveform as a piecewise combination of two coupled systems, the heart and arterial system which are decoupled upon closure of the aortic valve. Each of these dynamical systems has an inherent frequency of operation (ω1 and ω2) which gives information about LV function (ω1) as well as arterial dynamics (ω2).. METHODS: IF methodology is based on Sparse Time-Frequency Representation method. It uses an effective L2-minimization to extract the second intrinsic frequency (ω2) from an aortic pressure waveform. To examine the clinical relevance of this method, IF was applied to aortic pressure waveforms taken from published works. These aortic waveforms were selected from a healthy population free ...
AtCor Medical lead the world in the field of arterial pulse wave analysis and velocity systems. The SphygmoCor range provide tools for non-invasive assessment of the cardiovascular system and autonomic function.. Sphygmocor technology is based on a transfer function that derives the pressure wave at the ascending aorta. This transfer function is a patented algorithm of the properties of the brachial artery, providing important central data from a non-invasive recording of the pressure wave at the radial artery. SphygmoCor allows the physician to assess the cardiovascular state of the patient, where it really matters - at the heart. ...
The Journal of Healthcare Engineering is a peer-reviewed, Open Access journal publishing fundamental and applied research on all aspects of engineering involved in healthcare delivery processes and systems. It provides a vehicle for the exchange of advanced knowledge, emerging technologies, and innovative ideas among healthcare engineering researchers, engineers, managers, and consultants around the world.
Magnetic resonance imaging (MRI) was used to evaluate cerebrospinal fluid (CSF) pulsatile flow in eleven patients with hydrocephalus and three normal subjects. Multislice images were acquired using...
Numerical simulations of pulsatile blood flow through a symmetrical branch modeling the aortic bifurcation were carried out to assess several hemodynamic theories of atherogenesis by comparing the distribution of hemodynamic variables with that of early lesions in arterial branches. Considerable spatial and temporal variations in wall shear were found when the flow was pulsatile; the highest values occurred at the convex corner on the outer wall of the branch and in the neighborhood of the flow divider tip, and the lowest shears were experienced by the outer wall of the daughter vessel a short distance distal to the corner. Transient flow reversal occurred almost everywhere in the branch, and a transient separated region was found corresponding to the low-shear region in the daughter vessel. The shear profiles and the calculated separated region were influenced to some degree by the extent of flow development at the branch inlet and markedly by the branch area ratio. All of the proposed ...
Central blood pressure (CBP) parameters will be measured and used to derive the aortic augmentation index (AIx). The AIx quantifies the contribution of back-reflected outgoing systolic pressure waves to late-systolic central blood pressure, which increases with decreasing aortic compliance. AIx is measured by pulse wave analysis using the SphygmoCor System supplied by AtCor Medical. Results with a , 5% decrease in AIx were planned for analysis; results with a , 5% decrease in AIx were not analysed ...
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The flow waveform is the most interesting waveform. Much information can be derived from its shape. When flow is being used to generate a controlled level of pressure, the shape of the inspiratory flow waveform is informative regarding the necessary inspiratory time (if flow reaches zero, then the inspiratory time could be shorter without compromising volume). The expiratory flow pattern is also informative, as a slow return to baseline is an indication of the resistance to airflow.
Purpose.: To compare ocular rigidity (OR) and outflow facility (C) coefficients in medically treated open-angle glaucoma (OAG) patients and controls, and to investigate differences in ocular pulse amplitude (OPA) and pulsatile ocular blood flow (POBF) between the two groups. Methods.: Twenty-one OAG patients and 21 controls undergoing cataract surgery were enrolled. Patients with early or moderate primary or pseudoexfoliative OAG participated in the glaucoma group. A computer-controlled system, consisting of a pressure transducer and a microstepping device was employed intraoperatively. After cannulation of the anterior chamber, IOP was increased by infusing the eye with microvolumes of saline solution. IOP was recorded after each infusion step. At an IOP of 40 mm Hg, an IOP decay curve was recorded for 4 minutes. OR coefficients, C, OPA, and POBF were estimated from IOP and volume recordings. Results.: There were no differences in age or axial length in the two groups. The OR coefficient was ...
In accordance with an embodiment of the present technique, there is provided methods and systems for detecting the presence of venous pulsation by adjusting the sensitivity of a detection algorithm based on a sensor characteristic and/or notifying a caregiver of the presence of venous pulsation by ceasing display of physiological parameters. An exemplary embodiment includes receiving one or more signals from a sensor, the one or more signals corresponding to absorption of light in a patients tissue; calculating one or more physiological parameters of the patient based on the one or more signals; displaying the patients physiological parameters; enabling detection of venous pulsation with variable sensitivity based on a location of the sensor; and suspending or terminating the display of the one or more of the patients physiological parameters when venous pulsation is detected.
Objective: To test the hypothesis that an acute increase in plasma homocysteine produced by methionine is associated with an acute increase in pulse wave velocity.. Design: A double blind, cross over, placebo controlled design was used and pulse wave velocity, plasma homocysteine, total cholesterol: high density lipoprotein ratio, plasma triglyceride, oxidised low density lipoprotein cholesterol concentrations, apolipoproteins A1 and B, and C reactive protein were measured between 12.5 and 20 hours after methionine loading or placebo.. Results: Between 12.5 and 20 hours after exposure to a methionine loading test, arterial pulse wave velocity showed no significant difference compared with placebo. At 12 hours after exposure to the methionine loading test, in the presence of a controlled diet, triglyceride concentration significantly increased by 32.6% (p,0.02), cholesterol: high density lipoprotein ratio increased significantly by 22.5% (p,0.05) compared with placebo. Simultaneously, systolic ...
Abstract The incidence of acute kidney injury (AKI) after on-pump coronary artery bypass graft (CABG) varies among studies but can be reduced if pulsatile flow is used. The aim of this study is to evaluate pulsatile flow impact on renal function of elderly patients undergoing CABG. Over one year (April 2014 to April 2015) 48 patients above the age of 65 underwent on-pump CABG in our institute. Patients were divided into two groups; pulsatile flow (PFG) and non-pulsatile flow (NPFG) groups. Serum creatinine (S.Cr), creatinine clearance (Cr.Cl) and per-perfusion urine output (UO) were measured. AKI Network criteria were adopted for diagnosis. Mean age was 68 in PFG and 69 in NPFG. Males constituted 83.3% of PFG and 79.2% of NPFG. Although 37.5% of PFG and 41.7% of NPFG were hypertensive, all patients had normal ejection fraction (EF). Both groups had nearly 3 coronary anastomoses, cardiopulmonary bypass (CPB) time of 90 min, cross clamp time of 71 min and mean perfusion pressure of 70 mmHg. Mean
Pressure and flow were recorded in the ascending aorta of three dogs with aortic coarctation, induced surgically 3 months previously, and in three control litter mates. From these data were derived input impedance of the systemic circulation, pulsatile and steady components of external heart work, aortic systolic pressure-time index, and mean systolic and mean diastolic pressures. Results were correlated with intraoperative measurements of aortic pressure in three young patients with aortic coarctation and with records taken in another 24 patients during diagnostic catheterization. Distinctive changes in aortic impedance with coarctation were explained in terms of altered peripheral reflection. Such changes were responsible for characteristic alteration in central aortic pressure pulse contour and for change in other parameters, indicating impaired arterial function in accepting pulsatile flow from the heart. Such changes in the cushioning function appear responsible for many clinical features ...
The SphygmoCor® CP System The SphygmoCor CP system includes pulse wave analysis (PWA) software only. During a PWA measurement, a 10-second snapshot of the radial arterial pressure wave is measured using a tonometer. The SphygmoCor software derives the ascending aortic pressure wave, substantially equivalent to the pressure wave measured by an invasive catheter. From the aortic pressure wave, a number of valuable cardiovascular measurements are determined, including central aortic systolic pressure, aortic augmentation index and central pulse pressure ...
This study demonstrates that a pulsatile pattern of coronary blood flow is associated with impaired myocardial perfusion and poorer clinical outcomes. Prior studies have demonstrated that impaired epicardial blood flow, LAD culprit artery location, and multivessel or left main disease are all angiographic variables that are associated with poorer clinical outcomes after fibrinolytic administration for acute STEMI (1,14-18). This study extends these observations to demonstrate that a pulsatile pattern of epicardial blood flow is also associated with adverse clinical outcomes. A pulsatile flow pattern was associated with higher incidence of death or recurrent MI at 30 days even after adjusting for other confounding variables. In a multivariate model adjusting for previously identified correlates of angiographic reocclusion (14)(TFG, LAD, thrombus, percent diameter stenosis, eccentric lesion, ulcerated lesion, or collaterals) and clinical reinfarction (15)(PCI and age), the presence of pulsatile ...
Arteriovenous fistula (AVF) is the most widely used vascular access by patients undergoing hemodialysis, however, even though the most widely used access to AVF has a high failure rate, and can be affected by problems during its use, among the most common highlights intimal hyperplasia, thrombosis and stenosis. Studies suggest that recurrent problems in this type of access are directly linked to geometry, flow conditions and stiffness of the vascular wall by the vessels that compose it. The present work seeks to analyze the variation of pressure and flow in rigid and flexible AVF models manufactured from data from an actual patient undergoing treatment. The study was carried out from the acquisition and processing of the patients medical examinations (computed tomography), the creation of the geometry, treatment and modeling of said patient, the manufacturing of the AVF models by 3D printing and injection in mold, experimental analysis with pulsatile flow conditions, close to the real ...
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The results from this study suggest that AE has different effects on the cardiovascular system of men and women. The majority of studies assessing the effects of exercise training on BP and arterial function have been conducted in single-sex or mixed-sex populations, but without direct comparisons between the sexes [13-17]. To our knowledge, the present study is the first to directly compare differences between the sexes in the effects of exercise mode on resting hemodynamic parameters and variables of arterial stiffness in an unmedicated hypertensive cohort. The major novel finding of our study was that RE resulted in increases in central arterial stiffness in men, but not in women (Figure 1a,b). Conversely, AE produced a decrease in central arterial stiffness but no change in peripheral arterial stiffness for either sex. Another novel finding was that compared with AE, RE resulted in a greater increase in basal and peak FBF in both men and women (Figure 2a,b).. Several studies support our ...
and the pulsatility index (PI) are systematically varied within the human physiologic range. We show that the waveform PI is the key parameter that governs the vortex dynamics across the aneurysm neck and the flow patterns within the dome. At low PI, the flow in the dome is similar to a driven cavity flow and is characterized by a quasi-stationary shear layer that delineates the parent artery flow from the recirculating flow within the dome. At high PI, on the other hand, the flow is dominated by vortex ring formation, transport across the neck, and impingement and breakdown at the distal wall of the aneurysm dome. We further show that the spatial and temporal characteristics of the wall shear stress field on the aneurysm dome are strongly correlated with the vortex dynamics across the neck. We finally argue that the ratio between the characteristic time scale of transport by the mean flow across the neck and the time scale of vortex ring formation can be used to predict for a given sidewall ...
TY - JOUR. T1 - Precise quantification of pressure-flow waveforms during pulsatile and nonpulsatile perfusion. AU - Ji, Bingyang. AU - Undar, Akif. N1 - Copyright: Copyright 2008 Elsevier B.V., All rights reserved.. PY - 2007/5. Y1 - 2007/5. UR - http://www.scopus.com/inward/record.url?scp=34247496402&partnerID=8YFLogxK. UR - http://www.scopus.com/inward/citedby.url?scp=34247496402&partnerID=8YFLogxK. U2 - 10.1016/j.jtcvs.2006.10.076. DO - 10.1016/j.jtcvs.2006.10.076. M3 - Letter. C2 - 17467484. AN - SCOPUS:34247496402. VL - 133. SP - 1395. JO - Journal of Thoracic and Cardiovascular Surgery. JF - Journal of Thoracic and Cardiovascular Surgery. SN - 0022-5223. IS - 5. ER - ...
Central BP has been shown to more strongly reflect vascular disease and predict outcomes than traditional upper arm BP. Central BP can also determine the different effects of different hypertension medications when upper arm BP and pulse wave velocity do not. Central BP is the pressure that the heart has to pump against to get blood to flow to the rest of the body. Higher central BP means that the heart consumes more energy to pump blood. This can eventually lead to heart failure. Central BP also reflects the pressure in the blood vessels feeding the brain. If central BP is high, it this may lead to aneurysms and strokes.. Augmentation Index. The augmentation index is a ratio calculated from the pulse pressure waveform, and is a measure of wave reflection and arterial stiffness. Augmentation index is commonly accepted as a measure of the (augmentation) of central aortic pressure by a reflected pulse wave.. ...
Cardiovascular diseases are the leading cause of death worldwide. Pulse wave analysis (PWA) technique, which reconstructs and analyses aortic pressure waveform based on non-invasive peripheral pressure recording, became an important bioassay for cardiovascular assessment in a general population. The aim of our study was to establish a pulse wave propagation modeling framework capable of matching clinical PWA data from healthy individuals on a per-subject basis. Radial pressure profiles from 20 healthy individuals (10 males, 10 females), with mean age of 42 ± 10 years, were recorded using applanation tonometry (SphygmoCor, AtCor Medical, Australia) and used to estimate subject-specific parameters of mathematical model of blood flow in the system of fifty-five arteries ...
Cardiovascular diseases are the leading cause of death worldwide. Pulse wave analysis (PWA) technique, which reconstructs and analyses aortic pressure waveform based on non-invasive peripheral pressure recording, became an important bioassay for cardiovascular assessment in a general population. The aim of our study was to establish a pulse wave propagation modeling framework capable of matching clinical PWA data from healthy individuals on a per-subject basis. Radial pressure profiles from 20 healthy individuals (10 males, 10 females), with mean age of 42 ± 10 years, were recorded using applanation tonometry (SphygmoCor, AtCor Medical, Australia) and used to estimate subject-specific parameters of mathematical model of blood flow in the system of fifty-five arteries ...
The performance standards for equipment are as follows (table 2⇓). 1) The volume-measurement accuracy should be the same as that established by the ATS/ERS for spirometry 49; that is, ±3% volume accuracy (±3.5% accounting for 0.5% testing syringe error) over an 8-L volume range with test gases present in concentrations likely to be encountered during DL,CO tests. Pneumotachometer devices for sensing flow and volume during the DL,CO manoeuvre may be sensitive to different gas compositions, concentrations or pulsatile flow changes created by demand valves 50. All devices should maintain the required volume accuracy, regardless of the gas mixture, direction of gas flow (e.g. inhaled or exhaled), or pulsatile flow pattern. 2) Gas-analyser accuracy is important in some circumstances, such as measuring CO back pressure (the expired fraction of CO when no CO has been inhaled). However, in calculating DL,CO, only the ratios of alveolar to inhaled CO and tracer gas are needed. Thus, the analysers ...
The Arterial System. The Windkessel Effect Arterial Pressure Determinants CO TPR Changes in the Pulse Waveform. The hydraulic filter converts pulsatile flow to steady flow. Hydraulic filtering converts the intermittent output of the heart to a steady flow through the capillaries....
Airflow in the respiratory system has been predominantly studied in rigid ducts. Three-dimensional simulations are computationally expensive. One-dimensional (1-D) modelling offers a good compromise between accuracy and computational cost. In this work we described the propagation of air pulse in a model of human airways using the 1-D equations of flow in compliant vessels. Seven generations of bifurcations, starting from the trachea, were studied. Peripheral airways (from the 8(th) to 23(rd) generation) were modelled using lumped parameter models. Peripheral resistance values for normal and emphysematous lungs were taken from the literature. An acceleration pulse, very short in time, was enforced at the inlet of trachea. The results suggest that compression (positive pressure peaks) and expansion (negative pressure peaks) waves are generated according to the reflection coefficients of the corresponding reflection sites (bifurcations and terminal reflections). Different values for peripheral bronchial
Chapter 1- General Properties of Waves Reflection Seismology Geol 4068 Elements of 3D Seismology , 2nd Edition by Christopher Liner August 25, 2005 . Outline-I. General Properties of Waves Mechanical definition of a wave Physical Assumptions Wave descriptions Body waves Slideshow...
TY - JOUR. T1 - Non-invasive assessment of wave reflection phenomena in the central aorta. AU - Avolio, Alberto. AU - Cook, David. AU - Old, R. AU - Halliday, A. PY - 2002. Y1 - 2002. M3 - Conference paper. SP - 895. EP - 895. JO - Journal of Hypertension. T2 - Journal of Hypertension. JF - Journal of Hypertension. SN - 1473-5598. ER - ...
EUR/USD Elliott Wave analysis shows a three year expanded flat pattern is nearing an end. We are anticipating a bearish reversal that begins from a
This evening, one of my members forwarded me a public post made by another analyst about Elliott Wave analysis, which seemed to be supported by his novice acolytes. And, yes, that perspective...
The MiTiHeart® LVAD has been extensively evaluated in both in vitro and in vivo animal studies. The LVAD system has been successfully subjected to more than 5,000 hours of in vitro testing and 2,000 hours of animal implant testing. The latest MiTiHeart® LVAD system is compact, efficient and capable of long-term stable operation in vitro and in vivo. A total input power of 6 W was required at a design point of 4,100 rpm while pumping 5 L/min against 100 mmHg. This is among the lowest power reported by magnetically levitated LVADs found in literature. In Vitro testing showed low hemolysis under non-pulsatile and pulsatile conditions. NIH values are among the lowest reported in literature. Long-term durability testing has been demonstrated for 63 days of continuous operation while submerged in saline. Two successful chronic implant studies were performed. In both studies, the MiTiHeart® LVAD operated as expected with no device related complications. Recent test results will allow the MiTiHeart® ...
Kahkashan N et al authored manuscript titled Variation in carotid-femoral pulse wave velocity, augmentation pressure and augmentation index during different phases of menstrual cycle
TY - JOUR. T1 - Influence of sprint exercise on aortic pulse wave velocity and femoral artery shear patterns. AU - DeBlois, Jacob P.. AU - Lefferts, Wesley K.. AU - Heffernan, Kevin S.. PY - 2020. Y1 - 2020. N2 - Purpose: Aortic stiffness may affect shear patterns in the peripheral vasculature. This study examined if sprint exercise, which typically increases aortic stiffness is associated with increased peripheral retrograde blood flow and impaired microvascular function. Methods: Twenty participants (10 women; age: 27 ± 5 years) underwent arterial stiffness, shear rate, and microvascular function assessment at three time points: baseline; following time control; ~ 2 min post a 30-s cycle ergometer sprint against 7.0% body mass. Aortic stiffness was assessed using carotid-femoral pulse wave velocity (cfPWV). Superficial femoral artery (SFA) diameter and blood velocity were assessed using Doppler-ultrasound and were used to calculate shear rates and resistance index (RI). SFA wave reflections ...
Measurement of aortic Pulse Wave Velocity (PWVao) provides some of the strongest evidence concerning the prognostic significance of large artery stiffening
Ageing exerts differential effects on arterial stiffness and wave reflections. However, the impact of cardiovascular risk factors on arterial stiffness and wave reflections and, particularly, how such effects are influenced by ageing has not been assessed within a single large population, covering a sufficiently wide age range. Therefore, we determined the extent to which age alters the impact of traditional cardiovascular risk factors on arterial stiffness and wave reflections. Aortic stiffness and wave reflections were assessed in 4421 individuals (age range 18 to 92 years). When treated as continuous variables, clinic systolic, diastolic, and pulse pressures and glucose levels were independently associated with stiffness, and, with the exception of diastolic pressure, these associations were more marked in older individuals. In contrast, clinic systolic and diastolic pressures and smoking were independently associated with wave reflections, with stronger associations observed in younger ...
Arterial stiffness is an important risk factor for cardiovascular events. Radial augmentation index (AI r ) can be more conveniently measured compared with carotid-femoral pulse wave velocity (cfPWV). However, the performance of AI r in assessing arterial stiffness is limited. This study proposes a novel index AI rd , a combination of AI r and diastolic augmentation index (AI d ) with a weight α, to achieve better performance over AI r in assessing arterial stiffness. 120 subjects (43 ± 21 years old) were enrolled. The best-fit α is determined by the best correlation coefficient between AI rd and cfPWV. The performance of the method was tested using the 12-fold cross validation method. AI rd (r = 0.68, P , 0.001) shows a stronger correlation with cfPWV and a narrower prediction interval than AI r (r = 0.61, P , 0.001), AI d (r = −0.17, P = 0.06), the central augmentation index (AI c ) (r = 0.61, P , 0.001) or AI c normalized for heart rate of 75 bpm (r = 0.65, P , 0.001). Compared with AI r ...
Background: Carotid-femoral pulse wave velocity (cfPWV) is a reference measure of central (elastic) artery stiffness and a risk factor for cardiovascular disease. Femoral-ankle pulse wave velocity (faPWV) is a measure of peripheral (musculo-elastic) arterial stiffness. The ratio of fasting triglycerides (TG) to high-density lipoprotein cholesterol (HDL-C) is a novel and practical marker of insulin resistance (IR), a dysregulation that often precedes diabetes. While diabetes is a known risk factor for arterial stiffening, associations of IR with segment-specific measures of PWV, in those without diabetes, have not been well characterized.. Objective: To characterize the cross-sectional association of IR, as indexed by TG/HDL-C, with central and peripheral arterial stiffness by race and gender in older adults without diagnosed diabetes. We hypothesized that TG/HDL-C is positively associated with cfPWV and inversely associated with faPWV.. Methods: Our study population included 2477 white and 564 ...
Many studies show pathophysiological link between Type 2 Diabetes(T2DM), CardioVascular Diseases (CVD) and Arterial Stiffness. In this cross-section study 60 male Overweight, Obese adult patients of various durations of T2DM, 25to65 years age, of Western Rajasthan are examined for the arterial stiffness. Brachial-ankle Pulse Wave Velocities (BrAnkPWV) and carotid to femoral Pulse Wave Velocity (cfPWV) were taken as indices of central arterial stiffness. Brachial and ankle Arterial Stiffness Indexes (ASI) are taken as indices for corresponding local arterial stiffness. These parameters were measured by an automated oscillometric based device Periscope. Smokers and history of vascular diseases were excluded. Results stratified in groups of duration of T2DM, ,5 years, 6to 10 years and ,10years and compared. Regressions of PWVs and ASI on duration of T2DM were analysed unadjusted and adjusted for age, BMI and Blood Pressure. cfPWV, RBrAnkPWV & LBrAnkPWV are significantly higher in group of longer ...
TY - JOUR. T1 - Reference values of aortic pulse wave velocity in a large healthy population aged between 3 and 18 years. AU - Reusz, George S.. AU - Shroff, Rukshana. AU - Kis, Eva. AU - Cseprekal, Orsolya. AU - Fischer, Dagmar Christiane. AU - Haffner, Dieter. PY - 2013/2/1. Y1 - 2013/2/1. UR - http://www.scopus.com/inward/record.url?scp=84872866782&partnerID=8YFLogxK. UR - http://www.scopus.com/inward/citedby.url?scp=84872866782&partnerID=8YFLogxK. U2 - 10.1097/HJH.0b013e32835c021f. DO - 10.1097/HJH.0b013e32835c021f. M3 - Letter. C2 - 23303358. AN - SCOPUS:84872866782. VL - 31. SP - 424. EP - 425. JO - Journal of Hypertension. JF - Journal of Hypertension. SN - 0263-6352. IS - 2. ER - ...
Khoshdel, Ali R and Carney, Shane L (2009) Missing information in determining reference values of aortic pulse wave velocity in the elderly. Journal of Hypertension, 27 (6). pp. 1329-1330. ISSN 0263-6352 ...
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Carotid-femoral pulse wave velocity (cf-PWV) is a validated marker of arterial stiffening over the central arteries. Brachial-ankle pulse wave velocity (ba-PWV) integrates the mechanical properties from both the central and peripheral arteries and may be more representative than cf-PWV as arterial load for left ventricle (LV). We compared ba-PWV with ...
TY - JOUR. T1 - Nonpulsatile cardiopulmonary bypass disrupts the flow-metabolism couple in the brain. AU - Andersen, K.. AU - Waaben, J.. AU - Husum, B.. AU - Voldby, B.. AU - Bødker, A.. AU - Hansen, A. J.. AU - Gjedde, A.. PY - 1985. Y1 - 1985. N2 - The effect of cardiopulmonary bypass on the relationship between brain glucose consumption and regional blood flow is unknown. We measured this relationship in pigs subjected to 3 hours of pulsatile or nonpulsatile cardiopulmonary bypass at normothermia and compared the results to the relationship established in a control group of pigs. A total of 10 regions were sampled in both hemispheres of the porcine brain. In control pigs, cerebral blood flow averaged 46 ml/100 gm and the glucose consumption, 21 μmol/100 gm/min. The ratio between blood flow and glucose consumption was close to 2 ml/μmol in all regions. In pulsatile cardiopulmonary bypass both the whole-brain average and the regional values declined, so that the ratio remained the same, ...
Cardiovascular dynamics of tuna have been investigated by recording blood pressures and flows in the central circulation of both anaesthetised and swimming individuals. In anaesthetised fish (N=5), heart rate averaged 112+/−21 beats min-1 (mean +/− s.e.) and stroke volume was 0.67+/−0.24 ml kg-1 when normoxic water flowed over the gills. Ventricular diastolic pressure was zero until atrial contraction filled the ventricle. Ventral aortic pressures were high (mean 12.08+/−1.15 kPa), and blood flow was continuous in the ventral aorta throughout diastole. Dorsal aortic pressure (mean 6.3+/−1.28 kPa; N=4) and flow were both pulsatile. Pressure pulsatility (pulse pressure as a proportion of mean pressure) was about one-quarter of flow pulsatility, indicating considerable compliance in the dorsal aortic circulation. Total peripheral resistance averaged 0.17+/−0.4 kPa ml-1 kg-1 min-1 of which gill resistance averaged 48+/−15 % (N=4). For the ventral aorta, impedance modulus fell markedly ...
Based on research into the various paths the Covid-19 disease can track in the human body, its apparent that the entire body-from the inflammation in the brain to swelling (redness) in the toes-can be affected.. Its also recognized that people over the age of 65-especially those with comorbidities, such as hypertension, diabetes, cardiovascular, liver, and kidney disease, are at greater risk to complications, if the disease gains a foothold in the lungs.. With advanced age, there is also an inherent risk, without early lifestyle intervention, to vascular dysfunction-specifically arterial stiffness. In essence, the arteries become stiffer, which involves structural and functional changes-leading to cardiovascular and cerebrovascular disease.. Stiff arteries can lead to buffering changes in large, central arteries and increases in blood pressure, and blood flow pulsatility, comment researchers from the Human Performance Laboratory at Syracuse University in New York, who published Effects of ...
While central (carotid-femoral) foot-to-foot pulse wave velocity (PWV) is considered to be the gold standard for the estimation of aortic arterial stiffness, peripheral foot-to-foot PWV (brachial-ankle, femoral-ankle, carotid-radial) are being studied as substitutes of this central measurement. We present a novel methodology to assess theoretically these computed indices and the hemodynamics mechanisms relating them. We created a database of 3320 virtual healthy adult subjects using a validated one-dimensional model of the arterial hemodynamics, with cardiac and arterial parameters varied within physiological healthy ranges. For each virtual subject, foot-to-foot PWV were computed from numerical pressure waveforms at the same locations where clinical measurements are commonly taken. Our results confirm clinical observations: (i) carotid-femoral PWV is a good indicator of aortic stiffness, and correlates well with aortic PWV; (ii) brachial-ankle PWV over-estimates aortic PWV and is related to the ...
TY - JOUR. T1 - Intermittent versus constant aerobic exercise in middle-aged males. T2 - acute effects on arterial stiffness and factors influencing the changes. AU - Peres, D.. AU - Mourot, L.. AU - Ménétrier, A.. AU - Bouhaddi, M.. AU - Degano, B.. AU - Regnard, J.. AU - Tordi, N.. PY - 2018/8/1. Y1 - 2018/8/1. N2 - Purpose: Both constant and intermittent acute aerobic exercises have been found to decrease arterial stiffness. However, direct comparisons of these two types of exercise are sparse. It is not known which type of exercise has the greatest effect. Methods: We evaluated the haemodynamic responses in 15 males (age 48.5 ± 1.3 years; BMI 27.5 ± 0.8 kg m−2) following acute constant (CE) and intermittent cycling exercise (IE). Duration and heart rate were matched during both exercises (131.8 ± 3.2 bpm for CE and 132.0 ± 3.1 bpm for IE). Central and peripheral arterial stiffness was assessed through pulse wave velocity (PWV). Plasma concentrations of nitric oxide (NO), atrial ...
A cellular mechanism that senses shear force at the inner wall of a blood vessel and triggers remodeling that increases the circumference of the wall when a shear force threshold is exceeded would result in the observed scaling of vessel radii described by Murrays Law.
We showed that arterial remodeling evolutes overtime with an enlargement and a thinning of the carotid artery, leading to an increased carotid circumferential wall stress. This kind of arterial remodeling evolution is unusual in this high cardiovascular risk population. The pathophysiology of increased carotid circumferential wall stress is not obvious. In response to increased BP, in particular, the pulsatile component, degenerative changes, and fractures of the extracellular matrix component occur in the arterial wall, leading to arterial enlargement.14 The response to dilation is a thickening of the arterial wall, generally considered as adaptive, aiming at normalizing circumferential wall stress. We have previously shown in hypertensive patients that local pulse pressure was associated with increased diameter and intima-media thickness; however, circumferential wall stress was not fully normalized.15 In this study, we showed that this response does not occur in CKD patients and instead we ...
The pulmonary arteries have a relatively high-density of alpha-1 receptors [Rudner XL et al. Circulation 100: 2336, 1999], second only to hepatic/omental arteries. The pulmonary arteries also contains alpha receptors [Troncy E et al. Br J Anaesth 79: 631, 1997; Blaise G et al. Anesthesiology 99: 1415, 2003]. Therefore, it should be assumed that alpha-agonists can profoundly increase RV afterload.. While pulmonary vascular resistance is ~ 20% of SVR, pulmonary vascular impedance is 50% of systemic vascular impedance. The difference in the two is most likely related to the increased intensity of pulse wave reflections in the pulmonary vascular tree (impedance is related to vascular resistance, vascular compliance, and wave reflections, all of which oppose pulsatile blood flow) [Barash, PG. Clinical Anesthesia, 5th ed. (Philadelphia), p. 882, 2006]. Because SVR is such a poor indicator of afterload [Lang RM et al. Circulation 74: 1114, 1986], it may follow that PVR does not accurately predict ...
Tanaka H, DeSouza CA, Seals DR (1998) Absence of age-related increase in central arterial stiffness in physically active women. Arterioscler Thromb Vasc Biol 18(1):127-132 52. Zhu W, Hooker SP, Sun Y, Xie M, Su H, Cao J (2014) Associations of cardiorespiratory fitness with cardiovascular disease risk factors in middle-aged Chinese women: a cross-sectional study. BMC Womens Health 14:62. 1186/1472-6874-14-62 53. Quan HL, Blizzard CL, Sharman JE, Magnussen CG, Dwyer T, Raitakari O, Cheung M, Venn AJ (2014) Resting heart rate and the association of physical fitness with carotid artery stiffness. 07 m/s per year [26]. In summary, arterial stiffness increases linearly until approximately 50 years of age, after which time there is an acceleration of the stiffening process. Sex Due to sex related differences in CVD incidence, prevalence, morbidity and mortality [27], it is important to discuss the influence of sex on the progression of arterial stiffness. For example, discrepancies exist between sexes ...
Introduction: Atherosclerosis and osteoporosis are two major public health problems. These are both multifactorial and degenerative diseases that accompany aging. Co-morbidities are common, with a high prevalence of cardiovascular risk factors including hypertension, smoking, and sedentary lifestyle. Several studies have suggested a relationship between atherosclerosis and osteoporosis, with a significant correlation between coronary artery calcium and bone mineral density (BMD). The pulsatility index (PI) is designed to measure vascular resistance and characterizes the shape of the spectral waveform. The PI was increasing with age but alterations in PI are the reflection of multifactorial, pleiotropic events occurring in the cardio and cerebral vascular system. Atherosclerosis of the large proximal arteries and the intracranial vessels are important factors for increased PI.. Hypothesis: We hypothesized that the transcranial Doppler (TCD) PI would reflect the atherosclerotic component of ...
To examine the control of pulsatile insulin secretion by an intrapancreatic pacemaker, samples at minute intervals were taken from the portal vein in dogs in vivo and from an isolated perfused pancreas preparation in vitro. Anesthetized dogs had high amplitude pulsatile insulin secretion which was n …
We present evidence for the differential control of hemodynamics in influencing EC expression of GRP78, an ER chaperone responsible for alleviating cell toxicity and a key regulator of the UPR. To our knowledge, this is the first instance of GRP78 protein expression to be mechanically responsive, and further is differentially regulated in atheroprone versus atheroprotective regions in vivo and regulated by shear stress in a waveform specific manner in vitro. The mechanisms by which atheroprone flow induces increases in GRP78 were dependent on p38 activity and α2β1. The differential regulation of GRP78 protein and the ERSE activation by the onset of atheroprone flow signify the induction of the UPR and its sustained activity. Inflammatory cytokines found in atheroprone environments had no effect on GRP78 expression in ECs, and its regulation by known chemical agonists was independent of the p38 and α2β1 pathways. This result further accentuates the prominence of shear stress patterns in the ...
Introduction: Periodic acceleration (pGz) is a non-invasive method of increasing pulsatile shear stress to the endothelium. pGz is achieved by the sinusoidal head to foot motion to the supine body. pGz increases endogenous production of nitric oxide in whole animal models and isolated perfused vessel preparations, and is cardioprotective when applied prior to, during and after ischemia reperfusion. In part, the protective effects of pGz are attributable to nitric oxide (NO). The purpose of this investigation was to determine whether pGz up-regulates NOS isoforms in the endomyocardium. Methods and results: Fifteen swine weight 15-20kg, were anesthetized, instrumented to measure hemodynamics and randomized. Ten animals received 1h of pGz at 180cycles/min and Gz±3.9m/s2 [pGz] in addition to conventional ventilatory support and five served as time controls. Results: pGz produced a 2.3±0.4 and a 6.6±0.1 fold significant increase in eNOS and phosphorylated eNOS, 3.6±1.1 fold increase in nNOS, and ...
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University of Cincinnati , Department of Mechanical and Materials Engineering 2600 Clifton Ave., Cincinnati, Ohio 45221 , Phone 513 556 2738 ...
BCN is the official Publication of Neuroscience Departments of Tehran University of Medical Sciences and Shahid Beheshti University of Medical Sciences. BCN is an international multidisciplinary journal that publishes editorials, original full‐length research articles, short communications, reviews, methodological papers, commentaries, perspectives and
WATERS IGL® Pulsatile Perfusion Solution has a calculated potassium concentration of 25 mEq/L, a sodium concentration of 100 mEq/L, an osmolarity of 300 mOsM, and a pH of 7.4 at room temperature. Its ion composition is comparable with that of the intracellular milieu. ...
This study describes the effects of albuterol and NTG on the aortic pressure waveform. AIx, a quantitative index of systemic arterial stiffness,9 was calculated from aortic waveforms generated by PWA.10 Our main novel findings are that albuterol and NTG produce qualitatively and quantitatively similar and repeatable effects on AIx, that the effect of albuterol but not of NTG is inhibited by LNMMA and reduced in hypercholesterolemic subjects, and that the response to albuterol is correlated with the effect of ACh in the forearm vascular bed. These data indicate that the effect of albuterol is, in part, NO and endothelium dependent and are constistent with the presence of endothelial dysfunction in hypercholesterolemic subjects. Moreover, they suggest that PWA and administration of albuterol and NTG provide a simple, reliable, noninvasive method for assessing endothelial function, as we and others have previously hypothesized.23,24. As expected, inhalation of albuterol at the dose used reduced AIx ...
p=0.02). There were no significant differences between the two groups for gender, BMI, the number of smokers, medication of ACEI or ARB, the period of dialysis, the adequacy of dialysis (Kt/V), the values of the hematocrit, total cholesterol, triglyceride, LDL-cholesterol, phosphorus, the products of calcium and phosphorus, iPTH, the average MAP, DBP and HR and the echocardiographic parameters, except for the LVMi. Table 1 The main characteristics of the patient populace at baseline according to the groups of aortic pulse wave velocity Association between AoPWV and clinical parameters Pearsons correlation test was performed to examine the associations between AoPWV and the clinical parameters. The AoPWV value was positively correlated with age (r=0.40, p=0.01), the presence of diabetes (r=0.27, p=0.04), the serum calcium (r=0.31, p=0.02), the hs-CRP (r=0.38, p=0.01), the average pulse pressure (r=0.38, p=0.01), the LVMi (r=0.24, p=0.03) and the LAD (r=0.22, p=0.04), but the AoPWV value was ...
An apparatus for measuring a propagation velocity of a pulse wave which is propagated through an artery of a living subject, the apparatus including an electrocardiographic-waveform detecting device which detects an electrocardiographic waveform from the subject, a pulse-wave sensor which is adapted to be worn on the subject and which detects the pulse wave from the subject, a time-difference determining device for determining a time difference between a first periodic point relating to the detected electrocardiographic waveform and a second periodic point relating to the detected pulse wave, and a propagation-velocity determining means for determining the propagation velocity of the pulse wave based on the determined time difference.
Jo, CO.; Lande, MB.; Meagher, CC.; Wang, H.; Vermilion, RP. A Simple Method of Measuring Thoracic Aortic Pulse Wave Velocity in Children: Methods and Normal Values. American Society of Echocardiography. 2010; 23(7): 735-740. ...
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Future problems of childhood. Frame was extracted from the heart, fully traversing the left and right pulmonary artery pulsatility index and middle finger along the septum, findings in normal individuals, lv enddiastolic pressure. Rychik j etal. American college of radiology in their abilities, in older infants and children (american academy of pediatrics. An essential characteristic is transferred from the diet. Baschat aa, gembruch u. Prenat diagn 2011;26:2659. Other risk factors and prognosis for ulcerative colitis have similar 1year patency to svg, but very rarely develops in ~9% of these contexts, in the childs behavior in adolescents (approximately 17%). Svc pressure ultimately increases and ra pressure and poststenotic dilatation). Early clinical manifestations of hearing impairment involves mainly interference with normal ef and total colonic aganglionosis in hirschsprung disease. It is advisable for all parties; include as many senses as possible to assess the hidden p waves and go ...
Dr Ross Walker - Cardiologist For the past 25 years, newer technologies have been researched and introduced in the detection of heart disease, a central one being Pulse Wave Analysis (PWA). PWA is a simple, non-invasive test that measures each pulse emanating from the heart. This is conveniently measured at the wrist, thus not requiring disrobing, lying down or exercise. The computer then takes the information detected at the wrist and converts it (via a process known as a transfer function) to a central pulse. From the central pulse information, small and large vessel stiffness is measured and this has been shown in numerous studies to be an accurate predictor for future cardiac risk. Cholesterol, blood pressure, cigarette smoking, diabetes and family history are frequently used to evaluate the risk of cardiovascular disease. However, over the past decades there have emerged newer, more accurate screening techniques that have a much greater predictive value than traditional methods. Although ...
With a percutaneous femoral approach, iVAC2L can support with a pulsatile flow patients with impaired left ventricular function who require a mechanical circula
Great simulation explaining how the pressure flow model works in plants, good voice tutorial, online, easy to display with a pro-board or a projector. This site has an introduction, animation, conclusion, and quiz to better understand the topic. ...
One variable needed to promote accuracy of pulse oximetry results is the babys condition. When analyzing the baby for a pulsatile flow, there is a need for sufficient perfusion in the area being monitored. In this case, if the baby has weak or absent peripheral pulse, the reading from the pulse oximetry will often not be preci. ...
At Cellworks we have developed the Executive Health Assessment- making use of the latest in pathology markers, genetic testing, and blood pressure pulse wave analysis.
The respiratory time and flow profile at volitional exercise termination. Gross cycling efficiency is not altered with and without toe-clips
We are proud to announce an annual award, given by S+BmedVET: We would like to encourage interested veterinarians from all over the world to contribute to a better understanding of blood pressure and pulse wave analysis (PWA) including but not limited to pharmacologic modelling.(read more ,,) ...
The first 300 units CARDIOVIT AT-102 G2 have already been shipped. The instructions are taking place, as here in Finland with some of the Mehiläinen nurses. The Mehiläinen decision makers reveal the devices key qualities they wanted to adopt in their nationwide institution.. ...
A pulse wave measuring apparatus includes a pump (|b|9|/b|) and a three-port valve (|b|10|/b|). The pump (|b|9|/b|) includes an exhaust port (|b|91|/b|) and an intake port (|b|92|/b|), and performs an
PI is an indicator of the relative strength of the pulsatile signal from pulse oximetry and has been found to be a reliable indicator of peripheral perfusion. PI is calculated by dividing the pulsatile signal (AC) by the nonpulsatile signal (DC) times 100, and is expressed as a percent ranging from 0.02% to 20 ...
An Eulerian turbulent two phase flow model in cylindrical coordinates was developed in order to study evolving turbulent gas particle flows in a downward pipe flow. The model takes the feedback of the particles into account. Simulations shows good agreement with experiments and showed that the pipe length required for particle laden turbulent pipe flow to become fully developed is four times longer than for unladen flows, even for rather low mass loadings. The accumulation of particles in the near wall region showed a nonmonotonic behaviour and was found to be strongest for St=0.5.. ...
The results of a partial wave analysis of the $K\sp+\bar K\sp0\pi\sp-$ system produced in the reaction$$\pi\sp-p \to K\sp+\bar K\sp0\pi\sp-n$$at 18 GeV/c are presented. A total of 5612 events in the mass range 1.2-1.8 ...
EXCOR is a paracorporeal, pulsatile flow VAD. The device provides left ventricular, right ventricular or biventricular ... INCOR is an axial-flow pump for support of the left ventricle. In this system, the pump is implanted directly next to the heart ... The blood coming from the heart flows into the INCOR axial pump. The rotor in the pump has an active magnetic bearing while ... Like the heart, EXCOR blood pumps have valves which ensure that the blood only flows in one direction. The blood pumps are ...
In particular, wide-field imaging of pulsatile motion induced by blood flow can be measured on the thumb by digital holography ... Bencteux, Jeffrey (2015). "Holographic laser Doppler imaging of pulsatile blood flow". Journal of Biomedical Optics. 20 (6): ... and achieve high temporal resolution and full-field imaging capability of pulsatile blood flow. Heart rate monitor Clitoral ... blood flow to the periphery can be reduced, resulting in a PPG without a discernible cardiac pulse. In this case, a PPG can be ...
Collins GM, Halasz NA (1973). "The role of pulsatile flow in kidney preservation". Transplantation. 16 (4): 378-379. doi: ... in a machine that produced a pulsatile perfusate flow. Using this system Belzer had 6 dogs surviving after their kidneys had ... He used a mean pulsatile pressure of 20 mm Hg in 72-hour perfusions and found that this gave better results than mean pressures ... Joyce used non pulsatile perfusion at 4 °C with a perfusate containing Dextran 70 (Pharmacia) 2.1%, with additional ...
It can be used for pulsatile blood flow imaging. Electronic speckle pattern interferometry Holography Interferometry Powell RL ... "Pulsatile microvascular blood flow imaging by short-time Fourier transform analysis of ultrafast laser holographic ... "Holographic laser Doppler imaging of pulsatile blood flow". arXiv:1501.05776 [physics.optics]. Léo Puyo; Isabelle Ferezou; ... It can also be used to detect optical path length variations in transparent media, which enables, for example, fluid flow to be ...
... and greater reliability with continuous-flow LVADs compared to pulsatile-flow devices. As of mid 2015, Thoratec has the only ... The material is currently[when?] used in the Thoratec PVAD pulsatile-flow biventricular device. By 2000, the Thoratec VAD ... In a two-year randomized controlled clinical trial published in 2009 comparing pulsatile and continuous-flow LVADs, survival ... The technology is for use in a minimally invasive, acute cardiac axial-flow pump that can be delivered percutaneously in a ...
It may be pulsatile and can resemble a true aneurysm. A true aneurysm involves all three layers of the blood vessel. A ... This can cause blockage of the flow. A perivascular hematoma is a collection of blood that is external to the three vessel ... Due to being close to the vessel, it can also be pulsatile, and can be mistaken for a pseudoaneurysm or aneurysm. Femoral ... The "neck" of the pseudoaneurysm is the narrow path of blood flow between the artery, through the arterial wall, and into the ...
2007). "Comparisons of infection complications between continuous flow and pulsatile flow left ventricular assist devices". The ... and continuous-flow pumps. Pulsatile VADs use positive displacement pumps. In some pulsatile pumps (that use compressed air as ... less frequent adverse events and greater reliability with continuous flow LVADS compared to pulsatile flow devices. Of the 281 ... Continuous-flow VADs are smaller and have proven to be more durable than pulsatile VADs. They normally use either a centrifugal ...
Iberall, Arthur S.; Cardon, Samuel Z.; Young, Ed, On Pulsatile and Steady Arterial Flow - The GTS Contribution., Upper Darby, ... Effect of oxygen on cyclic red blood cell flow in unanesthetized mammalian striated muscle as determined by spectroscopy. ...
Doppler examination shows anechoic cystic areas, with pulsatile flow in spectral analysis. Some chorioangiomas may be solid ... When chorioangiomas have deceased blood flow, fetal hemodynamics and clinical outcome are found to be improved. It is the most ... Large chorioangiomas with decreased echogenicity, decreased tumor volume and decreased blood flow in colour doppler images are ...
Pulsatile shear and Gja5 modulate arterial identity and remodeling events during flow-driven arteriogenesis. Buschmann I*, ... Resistance to blood flow in microvessels in vivo. Pries AR, Secomb TW, Gessner T, Sperandio MB, Gross JF, Gaehtgens P. Circ Res ... Blood flow in microvascular networks. Pries AR and Secomb TW. In: Handbook of Physiology: Microcirculation, edited by Tuma RF, ...
But without functioning atria, venous flow becomes pulsatile, and the overall circulation rate decreases significantly. Atria ... to be able to accept venous flow without interruption. By preventing the inertia of interrupted venous flow that would ... In an adult, an atrial septal defect results in the flow of blood in the reverse direction - from the left atrium to the right ... At birth, when the first breath is taken fetal blood flow is reversed to travel through the lungs. The foramen ovale is no ...
It is a dimensionless expression of the pulsatile flow frequency in relation to viscous effects. It is named after John R. ... In a flow distribution network that progresses from a large tube to many small tubes (e.g. a blood vessel network), the ... The Womersley number of human blood flow can be estimated as follows: α = L ( ω ρ μ ) 1 2 . {\displaystyle \alpha =L\left({\ ... In these regions the inertia force becomes less important and the flow is determined by the balance of viscous stresses and the ...
... pulsatile mass above the umbilicus. A bruit may be heard from the turbulent flow in the aneurysm. Unfortunately, however, ...
doi:10.1007/s00134-005-2781-3. Bernstein, Donald P (2010). "Impedance cardiography: Pulsatile blood flow and the biophysical ... This flow data can be used in a flow-versus-time graph. The area under the flow-versus-time curve for one cardiac cycle is the ... Cardiac output is a global blood flow parameter of interest in hemodynamics, the study of the flow of blood. The factors ... which is then multiplied by the VTI of the Doppler flow profile across the aortic valve to determine the flow volume per beat ( ...
Endothelial cell specific nitric oxide synthase (EcNOS) is activated by the pulsatile flow of blood through vessels. Nitric ... Continuous diffusion of oxygen (CDO) - CDO delivers continuous oxygen to an occluded, moist wound site at much lower flow rates ... and arms due to distal nerve damage and low blood flow. Blisters and sores appear on numb areas of the feet and legs such as ... oxide produced by EcNOS, maintains the diameter of blood vessels and proper blood flow to tissues. In addition to this, nitric ...
Lim, W. L.; Chew, Y. T.; Chew, T. C.; Low, H. T. (2001-11-01). "Pulsatile flow studies of a porcine bioprosthetic aortic valve ... These models can combine the constant supersaturation principle together with pulsatile flow, which is characteristic of the ... This model does not provide the flow or the mechanical stimuli to the tissue. Both flow and mechanical stimuli affect the ... Dynamic models can vary in terms of the means of providing the flow in the system, as well as in terms of the dynamic ...
Skala has developed organ-on-a-chip devices to study pulsatile flow and how it impacts cardiovascular disease. She is ... "Measuring blood flow with a beating "heart-on-a-chip"". Morgridge Institute for Research. Retrieved 2020-11-19.CS1 maint: ...
The key difference here is that the blood flow is more pulsatile than with the Blalock-Taussig version. After this first step ( ... To accomplish this, blood flow to the lungs is disrupted, and therefore an alternative path must be created to supply the lungs ... After this surgery is completed, all the venous blood returning from the body flows directly to the lungs. The first successful ... An aortopulmonary shunt is created to connect the aorta to the main pulmonary artery to provide pulmonary blood flow. The ...
Agarwal, R. K.; Okpara, E (2010). "Numerical Study of Pulsatile Flow through Models of Vascular and Aortic Valve Stenoses and ... In practical terms, the flow from the left ventricular outflow tract (LVOT) is compared to the flow at the level of the aortic ... The continuity equation states that the flow in one area must equal the flow in a second area if there are no shunts between ... The flow through the LVOT, or LV stroke volume (in cm3), can be calculated by measuring the LVOT diameter (in cm), squaring ...
He discovered that venous blood flow is pulsatile which, prior to Rai's discovery, was described only as linear flow.[citation ...
Iberall, Arthur S.; Cardon, Samuel Z.; Young, Ed, On Pulsatile and Steady Arterial Flow - The GTS Contribution, Upper Darby, PA ... Iberall, A.S. "Anatomy and steady flow characteristics of the arterial system with an introduction to its pulsatile ... Iberall, A.S. Flow and pressure regulation in the cardiovascular system. In: W. Vannah and H. Wayland (eds.). Flow, Its ... and high altitude military led to his studies of high speed so-called speed-of-sound rates of flow, to more than one phase flow ...
"Pulsatile Flow in the Vascular System". So, C = ΔV/ΔP. Arterial compliance is an index of the elasticity of large arteries such ... and flow rate is Q=C(dP/dt) Q=flow rate (cm3/sec) The classic definition by MP Spencer and AB Denison of compliance (C) is the ...
Zhang suggests that this pulsatile brain activation is the inducer of each dream. He proposes that, with the involvement of the ... Braun, A. (1 July 1997). "Regional cerebral blood flow throughout the sleep-wake cycle. An H2(15)O PET study". Brain. 120 (7): ... This triggers the "continual-activation" mechanism to generate a data stream from the memory stores to flow through the ... A 2001 study showed evidence that illogical locations, characters, and dream flow may help the brain strengthen the linking and ...
After his work on the G-Suit, Wood worked on techniques for measuring cardiac blood flow. He was granted a patent for the ear ... The water-filled, pulsatile pressure suits were developed to effect venous return. However, Wood and colleagues' detailed ... Grace, JB; Fox, IJ; Crowley, WP Jr; Wood, EH (November 1957). "Thoracic-aorta flow in man". J Appl Physiol. 11 (3): 405-418. ... Smith, HC; Sturm, RE; Wood, EH (August 1973). "Videodensitometric system for measurement of vessel blood flow, particularly in ...
The compromised blood flow often causes collateral blood vessels to form. These are most often horizontal transpelvis ... In addition to compression, the vein develops intraluminal fibrous spurs from the effects of the chronic pulsatile compressive ... Compression becomes clinically significant only if it causes appreciable hemodynamic changes in venous flow or venous pressure ... which may compress it against the lumbar spine and limit the flow of blood out of the left leg. There are case reports of the ...
... the pulsatile blood flow forces the red blood cells to align in parallel with the blood flow. When the electric current is then ... 1 during flow time, and FT (flow time measured in s): S V T E B = C P ⋅ v ¯ F T ⋅ F T {\displaystyle SV_{TEB}=C_{P}\cdot {\bar ... Prior to opening of the aortic valve, the red blood cells (erythrocytes) assume a random orientation (there is no blood flow in ... The higher the mean blood velocity during flow time, the more SV the left ventricle ejects. The 'volume of electrically ...
... of the entire pulsatile energy within the system of pressure/flow oscillations in the peripheral circulation. It could be ... The flow velocity tracings are monitored during paradigm 1 comprising a checkerboard square as object perception are compared ... Although TCD is not so accurate due to relative velocity of blood flow, but it is still useful for diagnosis of arterial ... Once the desired blood vessel is found, blood flow velocities may be measured with a pulsed Doppler effect probe, which graphs ...
... give respite to an acutely injured myocardium the circulatory system transitions from a pulsatile mechanism to continuous flow ... Meyns, B; Stolinski, J; Leunens, V; Verbeken, E; Flameng, W (2003). "Left ventricular support by catheter-mounted axial flow ... Cellular response to cardiogenic shock is poorly described by either method (counterpulsation or continuous flow). Control of ... Lastly, augmented cardiac output and forward flow from the left ventricle decreases pulmonary capillary wedge pressure and ...
Phase contrast-MRI is an imaging method that is more sensitive than MRI for analysis of the pulsatile CSF flow in the ... The shunt also has a valve which serves to maintain one-way flow of the CSF and regulates the flow rate. The end with the ... If no flow is seen, this is a reliable diagnosis of aqueductal stenosis as it implies that there is a blockage of CSF. ... For example, if there is not enough CSF flow, another surgery is performed to lower the valve pressure so that less force needs ...
... and poor blood flow in the limbs which may lead to amputations.[1] The sudden onset of hyperosmolar hyperglycemic state may ...
... allowing for the shift from pulsatile water filled bladders to non-pulsatile air filled bladders, made by the Mayo ... While Professor Cotton's design was intriguing, he was more focused on center of gravity than on blood flow. This latter point ... to increase blood flow to the upper body.[citation needed] ...
Blood flow and velocityEdit. The pulsatile nature of blood flow creates a pulse wave that is propagated down the arterial tree ... Another system divides the aorta with respect to its course and the direction of blood flow. In this system, the aorta starts ... The difference between aortic and right atrial pressure accounts for blood flow in the circulation.[16] When the left ventricle ... McDonald's Blood Flow in Arteries: Theoretical, Experimental and Clinical Principles. 4th ed. London, UK: Edward Arnold; 1998 ...
Sismanis A (July 1998). "Pulsatile tinnitus. A 15-year experience". American Journal of Otology. 19 (4): 472-7. PMID 9661757.. ... The second theory posits that either increased blood flow to the brain or increase in the brain tissue itself may result in the ... The pain may also be experienced in the neck and shoulders.[5] Many have pulsatile tinnitus, a whooshing sensation in one or ... in phase contrast MRA studies have quantified cerebral blood flow (CBF) in vivo and suggests that CBF is abnormally elevated in ...
The rate of mean blood flow depends on both blood pressure and the resistance to flow presented by the blood vessels. In the ... The pulse pressure is a consequence of the pulsatile nature of the cardiac output, i.e. the heartbeat. The magnitude of the ... Angiotensin I flows in the bloodstream until it reaches the capillaries of the lungs where angiotensin converting enzyme (ACE) ... The blood pressure fall is detected by a decrease in blood flow and thus a decrease in glomerular filtration rate (GFR). ...
... leading to a net increase in renal blood flow (RBF) and glomerular filtration rate (GFR).[20] Glomerular hyperfiltration and an ...
Peterson LH, The Dynamics of Pulsatile Blood Flow, Circ. Res. 1954;2;127-139 ... Blood flow is also affected by the smoothness of the vessels, resulting in either turbulent (chaotic) or laminar (smooth) flow ... The study of the blood flow is called hemodynamics. The study of the properties of the blood flow is called hemorheology. ... Thurston assembled this layer to the flow resistance to describe blood flow by means of a viscosity η(δ) and thickness δ from ...
Cilia are capable of energy dependent pulsatile beating in a certain direction through interaction of cytoskeletal microtubules ... to flow in that direction (typically out of the body). Ciliated epithelium is found in the airways (nose, bronchi), but is also ... a secretory role in which a soluble protein is released to have an effect downstream of the fluid flow, and mediation of fluid ...
This inflow of blood cannot be cleared as quickly as it is coming in during the cold-stimulus headache, so the blood flow could ... and pulsatile (throbbing pain) phases of migraines.[12] ... of cold-stimulus headaches is explained by increased blood flow ...
... increased blood flow to the superior parts of the lung), and possibly pleural effusions. In contrast, patchy alveolar ... where the liver is enlarged and may be tender or even pulsatile. Other signs include end-inspiratory crackles (sounds heard at ... can cause pulmonary edema as the elevation in blood pressure and increased afterload on the left ventricle hinders forward flow ...
TSH release in turn is stimulated by thyrotropin releasing hormone (TRH), released in a pulsatile manner from the hypothalamus. ... these factors increase blood flow and the body's temperature.[26] ...
"Assessment of a novel stentless mitral valve using a pulsatile mitral valve simulator". The Journal of Heart Valve Disease. 21 ... "Continuous-flow total artificial heart supports long-term survival of a calf". Texas Heart Institute Journal. 36 (6): 568-74. ...
Modeling Viscoelastic Behavior of Arterial Walls and their Interaction with Pulsatile Blood Flow, Journal of Applied ... This explains why the elastic portion is only noticeable in unsteady flow. In steady flow, the slippage will continue to ... Initial studies had evaluated blood during steady flow and later, using oscillating flow. Professor George B. Thurston, of the ... The early studies used the properties found in steady flow to derive properties for unsteady flow situations. Advancements in ...
Murasko, K.M., Chen R.Y.Z., Carlin, R.D., Antunes, J.L., Chien, S.: Effects of naloxone on regional blood flow in hypovolemia. ... Induction of ovulatory menstrual cycles by an unvarying pulsatile GnRH infusion in pituitary stalk-sectioned rhesus monkey. ... Chen, R.Y.Z., Murasko, K.M., Charlin, R.D., Antunes, J.L., Chien, S.: Improvement of cerebral and myocardial blood flows by ... Solomon, R.A., Antunes, J.L., Chen, R.Y.Z., Bland, L. Chien, S.: Decrease in cerebral blood flow in rats after experimental ...
This leads to blood cell aggregation and increased blood viscosity which results in impaired blood flow.[12] ...
The pump is approximately one-tenth the size of other currently marketed pulsatile VADs. Because of the pump's small size, ... Langley Research Center's wind tunnel testing facilities and fluid flow analysis software supported Speedo's design of a space ...
Hard signs include active bleeding, expanding or pulsatile hematoma, bruit/thrill, absent distal pulses and signs of extremity ... unstable blood flow, respiratory distress) should immediately receive a chest tube (, French 36) or needle decompression if ...
Blood vessels depend on normal nerve function, and nerves depend on adequate blood flow. The first pathological change in the ... Blood vessel opening agents (e.g., ACE inhibitors, α1-antagonists) can lead to substantial improvements in neuronal blood flow ... The nitric oxide in turn promotes vasodilation which results in increased blood flow that helps nourish damaged nerve cells. ... of the heart and arteries to appropriately adjust heart rate and vascular tone to keep blood continually and fully flowing to ...
Measurement of real pulsatile blood flow using X-ray PIV technique with CO2 microbubbles, Hanwook Park, Eunseop Yeom, Seung-Jun ... According to very recent results showing the sheath flow surrounding the plug flow in a vessel,[7] the sheath flow size is not ... will result in an increased flow to tissues and an increased venous flow back to the heart. An increased SVR will decrease flow ... It is proportional to the mass flow rate and blood viscosity.. F. =. Q. c. L. η. (. δ. ). /. (. π. δ. r. ). {\displaystyle F= ...
... provide continuous flow. These pumps (which may be centrifugal or axial flow) are smaller and potentially more durable and last ... Imachi K, Chinzei T, Abe Y, Mabuchi K, Imanishi K, Yonezawa T, Kouno A, Ono T, Atsumi K, Isoyama T (1991). "A new pulsatile ... A centrifugal pump[70][71] or an axial-flow pump[72][73] can be used as an artificial heart, resulting in the patient being ... Several continuous-flow ventricular assist devices have been approved for use in the European Union, and, as of August 2007, ...
... day one is the first day of menstrual flow). The cohort of small antral follicles is normally sufficient in number to produce ... factor produced by small follicles during the first half of the follicle phase also exerts a negative feedback on pulsatile ...
Many have pulsatile tinnitus, a whooshing sensation in one or both ears (64-87%); this sound is synchronous with the pulse. ... The second theory posits that either increased blood flow to the brain or increase in the brain tissue itself may result in the ... in phase contrast MRA studies have quantified cerebral blood flow (CBF) in vivo and suggests that CBF is abnormally elevated in ... Little evidence has accumulated to support the suggestion that increased blood flow plays a role, but recently Bateman et al. ...
Jørgensen, LG; Perko, M; Hanel, B; Schroeder, TV; Secher, NH (March 1992). "Middle cerebral artery flow velocity and blood flow ... pulsatile tinnitus and/or transient visual obscurations CSF opening pressure > 25 cm H2O Optic-disc edema will be graded based ... Jørgensen, LG; Perko, G; Secher, NH (November 1992). "Regional cerebral artery mean flow velocity and blood flow during dynamic ... "Carotid artery blood flow and middle cerebral artery blood flow velocity during physical exercise". Journal of Applied ...
The pumping action of the heart generates pulsatile blood flow, which is conducted into the arteries, across the micro- ... Thurston assembled this layer to the flow resistance to describe blood flow by means of a viscosity η(δ) and thickness δ from ... The rate of mean blood flow depends on both blood pressure and the resistance to flow presented by the blood vessels. Mean ... The study of the blood flow is called hemodynamics. The study of the properties of the blood flow is called hemorheology. Blood ...
The pathway and extent are currently not known,[1] but may involve CSF flow along some cranial nerves and be more prominent in ... Fluid movement is pulsatile, matching the pressure waves generated in blood vessels by the beating of the heart.[3] Some ... CSF also serves a vital function in the cerebral autoregulation of cerebral blood flow. ... which act to prevent most substances flowing freely into CSF.[19] Cilia on the apical surfaces of the ependymal cells beat to ...
They may be divided into low-flow or high-flow, traumatic or spontaneous and direct or indirect. The traumatic CCF typically ... and pulsatile proptosis or progressive bulging of the eye due to dilatation of the veins draining the eye. Pain is the symptom ... CCF symptoms include bruit (a humming sound within the skull due to high blood flow through the arteriovenous fistula), ... "Treatment of a traumatic carotid-cavernous fistula by the sole use of a flow diverting stent". Journal of NeuroInterventional ...
High flow oxygen therapy also helps with relief.[5]. For people with extended periods of cluster headaches, preventive therapy ... primary exertional headache: throbbing, pulsatile pain which starts during or after exercising, lasting for 5 minutes to 24 ... Temporal arteritis is an inflammation of vessels close to the temples in older people, which decreases blood flow to the brain ...
In fluid dynamics, a flow with periodic variations is known as pulsatile flow, or as Womersley flow. The flow profiles was ... The cardiovascular system of chordate animals is a very good example where pulsatile flow is found, but pulsatile flow is also ... The pulsatile flow profile is given in a straight pipe by u ( r , t ) = R e { ∑ n = 0 N i P n ′ ρ n ω [ 1 − J 0 ( α n 1 / 2 i 3 ... The pressure gradient driving the pulsatile flow is decomposed in Fourier series, ∂ p ∂ x ( t ) = ∑ n = 0 N P n ′ e i n ω t ...
... shear-thinning fluid representing blood flow in a large artery. ... Results of Laser-Doppler-Anemometry of pulsatile flow in a ... Results of Laser-Doppler-Anemometry of pulsatile flow in a curved tube of a Newtonian (left) and non-Newtonian (right) shear- ... Flow past a confined excentric cylinder and in our cross-slot device ...
Fiber-based laser speckle imaging for the detection of pulsatile flow.. Regan C1,2, Yang BY1, Mayzel KC1,2, Ramirez-San-Juan JC ... Data from in vitro and in -vivo tests strongly suggest that this probe can detect the presence of pulsatile flow. LSI may ... In this study, we designed and characterized a fiber-based laser speckle imaging system to study pulsatile blood flow in the ... To assess our ability to detect changes in pulsatile flow, we performed in vitro and preliminary in vivo tests on tissue- ...
... a model of pulsatile flow in an elastic tube is analyzed. A new and exact solution for flow velocity, blood flow rate and shear ... Pulsatile blood flow, shear force, energy dissipation and Murrays Law Theor Biol Med Model. 2006 Aug 21;3:31. doi: 10.1186/ ... Furthermore, the hypothesis that the maximum shear force during the cycle of pulsatile flow is constant throughout the arterial ... Results: For medium and small arteries with pulsatile flow, Murrays energy minimization leads to Murrays Law. ...
The unsteady flow of blood in a straight arterial segment, driven by an oscillatory pressure gradient, is studied. A ... The unsteady flow of blood in a straight arterial segment, driven by an oscillatory pressure gradient, is studied. A ... 1 Introduction The possibility to predict the flow of blood through natural and artificial vessels has stimulated much research ... the characteristics of blood flow, such as the high values of the shear stress at the wall or its variations [l]-[3]. In this ...
"Pulsatile Flow" by people in Harvard Catalyst Profiles by year, and whether "Pulsatile Flow" was a major or minor topic of ... "Pulsatile Flow" is a descriptor in the National Library of Medicines controlled vocabulary thesaurus, MeSH (Medical Subject ... Comparison of heart transplant outcomes between recipients with pulsatile- vs continuous-flow LVAD. J Card Surg. 2019 Oct; 34( ... Below are the most recent publications written about "Pulsatile Flow" by people in Profiles. ...
... experimental and theoretical models of microbubble transport in pulsatile flow are presented. The one-dimensional t ... However, bubble lodging was affected by the flow pulsatility, and the effects of pulsatile flow were evident in the dependence ... When compared to corresponding constant flow, pulsatile flow was shown to produce insignificant changes to the overall ... 9309989 - Expiratory flow limitation in stable asthmatic patients during resting breathing.. 7507319 - Laminar flow stimulates ...
In comparison to the customary steady flow blood pump of the prior art, the pulsatile flow blood pump clears urea, a low ... Large molecules, such as vitamin B 12 are also cleared more rapidly by the pulsatile flow pump, but less rapidly than the ... Total time of dialysis is reduced and the results obtained by using the pulsatile flow blood pump are more physiologic, in that ... molecular weight molecule, from the bood approximately three times as fast as does the steady flow roller pump commonly used on ...
Catheterization increases the mean flow resistance in the arterial blood flow and many other complications are associated with ... The effect of slip at the arterial wall, inclination of the artery and magnetic field on the hemodynamic indicators and flow ... Liu, Z.-R., Xu, G., Chen, Y., Teng, Z.-Z. and Qin, K.-R. (2003) An Analysis Model of Pulsatile Blood Flow in Arteries. Applied ... Sharma, M. , Singh, K. and Bansal, S. (2014) Pulsatile MHD Flow in an Inclined Catheterized Stenosed Artery with Slip on the ...
... pulsatile blood flow, pulsatile flow, relative residence time, Stress, Wall shear stress Abstract:. Hemodynamics in large human ... To the best of our knowledge, in pulsatile flow, this is the first theoretical study elaborating on hemodynamic factors such as ... Shailendhra K., and Gayathri K., "Pulsatile blood flow through large arteries with BJR slip condition", 2016 International ... Our model can predict the biological response of the artery in the normal/abnormal flow regime in a much better way, if the ...
Stroke Volume Pulsatile Flow Vary Stroke Volume Acceleration Phase Impedance Cardiography These keywords were added by machine ... J. C. Faes and R. M. Heethaar (1996) The influence of pulsatile flow on blood resistivity in impedance cardiography. 18th Annu ... Gaw R., Cornish B., Thomas B. (2007) The electrical impedance of pulsatile blood flowing through rigid tubes: an experimental ... The electrical impedance of pulsatile blood flowing through rigid tubes: an experimental investigation. ...
... Wåhlin, Anders Umeå ... This work focused on assessing the pulsatile waveform of cerebral arterial, venous and CSF flows. The overall aim of this ... Arterial Pulsatility, cerebrospinal fluid, cerebral blood flow, venous flow, intracranial pressure, pulse pressure, dementia, ... this work showed that 2D PCMRI is a feasible tool to study the pulsatile waveforms of cerebral blood and CSF flow. Conventional ...
Measuring Pulsatile Flow in Cerebral Arteries Using 4D Phase-Contrast MR Imaging. A. Wåhlin, K. Ambarki, R. Birgander, O. ... Measuring Pulsatile Flow in Cerebral Arteries Using 4D Phase-Contrast MR Imaging ... Measuring Pulsatile Flow in Cerebral Arteries Using 4D Phase-Contrast MR Imaging ... Measuring Pulsatile Flow in Cerebral Arteries Using 4D Phase-Contrast MR Imaging ...
purpose. Choroidal blood flow may be determined by pulsatile ocular blood flow (POBF) measurements. In the present study, the ... Validity of pulsatile ocular blood flow measurements. Surv Ophthalmol. 1994;38(suppl)S72-S80. [CrossRef] [PubMed] ... Postural studies in pulsatile ocular blood flow: ocular hypertension and normotension. Br J Ophthalmol. 1991;75:66-70. [ ... Pulsatile ocular blood flow in asymmetric exudative age related macular degeneration. Br J Ophthalmol. 2001;85:1411-1415. [ ...
The unsteady pulsatile flow of blood through porous medium in an artery has been studied under the influence of periodic body ... The unsteady pulsatile flow of blood through porous medium in an artery has been studied under the influence of periodic body ... Elshehawey, E.F., Elbarbary, E.M.E., Afifi, N.A.S. and El-Shahed, M. (2000) Pulsatile Flow of Blood through a Porous ... Abdelnaby, M.A., Eldabe, N.T.M. and Abouzeid, M.Y. (2006) Numerical Study of Pulsatile MHD Non-Newtonian Fluid Flow with Heat ...
Flow waveforms were generated using a programmable pulsatile pump to mimic the heart functions. Phase-locked PIV were conducted ... Abstract: M03.00009 : An experimental study of pulsatile flow over rectangular sidewall cavities. 3:28 PM-3:29 PM ... This study represents a systematic experimental effort towards pulsatile flow over a standard cavity model, which could serve ... However, how the flow pulsatility affects the vortex dynamics of the cavity flow is still not fully understood. Such question ...
Ocular pulse measurements to assess pulsatile blood flow in carotid artery disease. ... Ocular pulse measurements to assess pulsatile blood flow in carotid artery disease. ...
Flow patterns in the jugular veins of pulsatile tinnitus patients. J Biomech 2017;52:61-67 doi:10.1016/j.jbiomech.2016.12.008 ... The protocol included flow assessment and rating of pulsatile tinnitus intensity before and after lumbar puncture and MR ... Reduced Jet Velocity in Venous Flow after CSF Drainage: Assessing Hemodynamic Causes of Pulsatile Tinnitus. H. Haraldsson, J.R ... Our results further show a correlation between the peak velocity and pulsatile tinnitus intensity, suggesting the flow jet to ...
Pulsatile energy may be a potential promoter of vascular development. Pulsatile pressure-flow relationships are also critical ... of pulsatile pressure-flow relations has been shown in vascular systems. Several factors, including flow turbulence in the ... Linearity of Pulsatile Pressure-Flow Relations in the Embryonic Chick Vascular System. Masaaki Yoshigi, Bradley B. Keller ... Linearity of Pulsatile Pressure-Flow Relations. We evaluated the scatter of the harmonics along a reference curve as a ...
Hemodynamic assessments of venous pulsatile tinnitus using 4D-flow MRI. Yunduo Li, Huijun Chen, Le He, Xiangyu Cao, Xianling ... Hemodynamic assessments of venous pulsatile tinnitus using 4D-flow MRI. Yunduo Li, Huijun Chen, Le He, Xiangyu Cao, Xianling ... Objective To use 4D-flow MRI to characterize hemodynamics of transverse and sigmoid sinus in venous pulsatile tinnitus (PT) ... average blood flow (Flowavg), and pulsatility index (PI) between PT and control group. ...
002 Can non-pulsatile continuous-flow left ventricular assist devices confer physiologically desirable cardiac and physical ... 002 Can non-pulsatile continuous-flow left ventricular assist devices confer physiologically desirable cardiac and physical ... Conclusion We have shown for the first time that complementary to reported prognostic benefits, non-pulsatile continuous-flow ... and functional capacity of patients as compared with the pulsatile-flow LVAD. To date, no study has reported how well HeartMate ...
A. C. Belliveau, R. P. LeBlanc, B. C. Chauhan, M. T. Nicolela; Pulsatile Ocular Blood Flow in Glaucoma Patients With Different ... Purpose:: To evaluate the baseline pulsatile ocular blood flow measurements (POBF) of open-angle glaucoma patients enrolled in ... Pulsatile Ocular Blood Flow in Glaucoma Patients With Different Optic Disc Phenotypes ... Pulsatile Ocular Blood Flow in Glaucoma Patients With Different Optic Disc Phenotypes ...
Calculations of pulsatile flow through a branch: implications for the hemodynamics of atherogenesis.. M H Friedman, V OBrien, ... Numerical simulations of pulsatile blood flow through a symmetrical branch modeling the aortic bifurcation were carried out to ... Considerable spatial and temporal variations in wall shear were found when the flow was pulsatile; the highest values occurred ... Calculations of pulsatile flow through a branch: implications for the hemodynamics of atherogenesis. ...
A hybrid method for investigating pulsatile fluid flow in a long, thin, artery-like tube subjected to external excitations is ... vibration, dynamic response, elastic tubes, arteries, pulsatile flow, finite element method, Mechanical engineering and ... The vibration of an artery-like tube conveying pulsatile fluid flow. Proceedings of the Institution of Mechanical Engineers, ... An analysis of these coupling effects is presented for Womersley numbers α = 2.81 and 3.97 and a mean flow Reynolds number Re ...
... the contribution of arterial radius and center-line velocity to the blood conductivity and electrical impedance of pulsatile ... flow in the human common carotid artery, we... ... The influence of pulsatile flow on blood resistivity in ... Liu ZR, Xu G, Chen Y, Teng ZZ, Qin KR (2003) An analysis model of pulsatile blood flow in arteries. Appl Math Mech 24(2):230- ... Ling SC, Atabek HB (1972) A nonlinear analysis of pulsatile flow in arteries. J Fluid Mech 55(3):493-511Google Scholar ...
Continuous Flow And Pulsatile Flow Devices Compared. Daisuke Yoshioka, Koichi Toda, Yasushi Yoshikawa, Manabu Sakaguchi, Shuhei ... Continuous Flow And Pulsatile Flow Devices Compared. Daisuke Yoshioka, Koichi Toda, Yasushi Yoshikawa, Manabu Sakaguchi, Shuhei ... Continuous Flow And Pulsatile Flow Devices Compared. Daisuke Yoshioka, Koichi Toda, Yasushi Yoshikawa, Manabu Sakaguchi, Shuhei ... Continuous Flow And Pulsatile Flow Devices Compared ... for patients with severe heart failure than pulsatile flow LVAD ...
The model corresponds to blood flows through small diameter porous conical vessels. This approach is based on a finite ... A theoretical study concerning two-component fluid pulsating flow through porous conical ducts is presented. ... Two-phase pulsatile flows through porous conical tubes of small diameters. Modelisation of the blood microcirculation Article ... The model corresponds to blood flows through small diameter porous conical vessels. This approach is based on a finite ...
This fluid flow is pulsatile to increase turbulence, reducing areas of stagnant flow, and produces a desired cooling effect. ... The electrode includes passages positioned to allow saline flow out of an inner cavity of the electrode. ... a pump system configured to generate a pulsatile flow,. wherein the pulsatile flow is configured to flow through the one or ... Alternatively, the total flow could remain the same with pulsatile flow as with steady state flow. ...
Pulsatile blood flow interaction with arterial walls of aorta : autoregulation and impedance pressure boundary condition and ... Pulsatile blood flow interaction with arterial walls of aorta : autoregulation and impedance pressure boundary condition and ... Afkari, Damon (2015). Pulsatile blood flow interaction with arterial walls of aorta : autoregulation and impedance pressure ... considering the interaction of the arterial walls with the pulsatile blood flow. The effect of surrounding tissues is ...
17] K. Perktold, R. Peter and M. Resch, Pulsatile non-newtonian blood flow simulation through a bifurcation with an aneurysm. ... The pulsatile flow of incompressible newtonian blood is illustrated by numerical simulations carried out in two saccular ... Medical image - based computational model of pulsatile flow in saccular aneurisms Salmon, Stéphanie; Thiriet, Marc; Gerbeau, ... Medical image - based computational model of pulsatile flow in saccular aneurisms. ESAIM: Mathematical Modelling and Numerical ...
  • The flow profiles was first derived by John R. Womersley (1907-1958) in his work with blood flow in arteries. (wikipedia.org)
  • For medium and small arteries with pulsatile flow, Murray's energy minimization leads to Murray's Law. (nih.gov)
  • McDonald, D.A. (1960) Blood Flow in Arteries. (scirp.org)
  • Srivastava, V.P. (2002) Particulate Suspension Blood Flow through Stenotic Arteries: Effect of Hematocrit and Stenosis Shape. (scirp.org)
  • Misra, J.C. and Shit, G.C. (2007) Role of Slip Velocity in Blood Flow through Stenosed Arteries: A Non-Newtonian Model. (scirp.org)
  • BACKGROUND AND PURPOSE: 4D PCMRI can be used to quantify pulsatile hemodynamics in multiple cerebral arteries. (diva-portal.org)
  • The aim of this study was to compare 4D PCMRI and 2D PCMRI for assessments of pulsatile hemodynamics in major cerebral arteries. (diva-portal.org)
  • The parameters that were varied during the course of the experimentation include the frequency of the flow pulsation, tubular materials having various structural properties, and blockages of the tube cross sections to simulate the presence of plaque in arteries. (wayne.edu)
  • We have validated a new radiographic technique for determining pulsatile volume flow in arteries following an intraarterial injection of contrast material. (ucl.ac.uk)
  • In-vitro pulsatile flow visualization studies were conducted in an adult-sized pulmonary artery model to observe the effects of valvular pulmonic stenosis on the flow fields of the main, left and right pulmonary arteries. (asme.org)
  • and twisted (or tortuous) arteries, which pinch blood flow and cause it to become turbulent. (tinnitusformula.com)
  • If pulsatile tinnitus originates in the arteries, pressure applied to the upper neck on the side of the tinnitus should alter or reduce it. (tinnitusformula.com)
  • Medical puzzle: can blood flow in arteries be non-pulsatile? (stackexchange.com)
  • Can the blood flow in arteries of a living human be non-pulsatile (i.e. not producing a pulse)? (stackexchange.com)
  • Direct numerical simulations (DNS) of steady and pulsatile flow through 75% (by area reduction) stenosed tubes have been performed, with the motivation of understanding the biofluid dynamics of actual stenosed arteries. (cambridge.org)
  • Pulsatile tinnitus (tinnitus that beats with your pulse) can be caused by aneurysms, increased pressure in the head (hydrocephalus), and hardening of the arteries. (amazonaws.com)
  • McDonald's blood flow in arteries : theoretic, experimental, and clinical principles. (worldcat.org)
  • I thought you might be interested in this item at http://www.worldcat.org/oclc/772714756 Title: McDonald's blood flow in arteries : theoretic, experimental, and clinical principles. (worldcat.org)
  • McDonald's Blood Flow in Arteries' provides the theoretical basis required for the understanding of arterial blood flow, both in normal and in disease conditions including pulmonary hypertension, atherosclerosis and heart failure. (worldcat.org)
  • Revised edition of: McDonald's blood flow in arteries / Wilmer W. Nichols and Michael F. O'Rourke. (worldcat.org)
  • Add tags for "McDonald's blood flow in arteries : theoretic, experimental, and clinical principles. (worldcat.org)
  • 1) The heart pumps blood in arteries as a pulsatile flow. (wikibooks.org)
  • Moving from great arteries to capillaries, the compliance of blood vessels converts the pulsatile flow into a continuous one by the time it reaches the cells. (wikibooks.org)
  • Objectives We hypothesized that recognition of systolic flow reversal (pulsatile flow) after thrombolytic administration on coronary angiography is associated with angiographic and electrocardiogram findings reflecting impaired myocardial perfusion, as well as poorer clinical outcomes. (onlinejacc.org)
  • Background Reversal of systolic flow on Doppler velocity wire recordings has been associated with impaired tissue perfusion on myocardial contrast echocardiography in the setting of myocardial infarction (MI). (onlinejacc.org)
  • Conclusions A pulsatile pattern of flow is associated with impaired myocardial perfusion and poorer clinical outcomes independent of the velocity of antegrade flow in the epicardial artery. (onlinejacc.org)
  • However, despite the presence of normal epicardial Thrombolysis In Myocardial Infarction (TIMI) grade 3 flow (TFG), impaired myocardial perfusion on coronary arteriography has also been independently associated with increased mortality (1) . (onlinejacc.org)
  • Ji, B & Undar, A 2007, ' Precise quantification of pressure-flow waveforms during pulsatile and nonpulsatile perfusion ', Journal of Thoracic and Cardiovascular Surgery , vol. 133, no. 5, pp. 1395. (elsevier.com)
  • Pulsatile perfusion technique is a simple and safe measure to minimize AKI in the elderly. (edu.iq)
  • IMSEAR at SEARO: Ocular Perfusion Pressure and Pulsatile Ocular Blood Flow in Normal and Systemic Hypertensive Patients. (who.int)
  • Purpose: The purpose was to compare the ocular perfusion pressure (OPP) and the pulsatile ocular blood flow (POBF) in normal and systemic hypertensive patients. (who.int)
  • Pulsatile perfusion (PP) can provide specific conditions for supplementary GMB-activity with respect to non-pulsatile (NP). (uniba.it)
  • 0.001) detected in arterial line during PP. Despite the differences in filtering capacity of all circuits with both types of perfusion, no important differences in clinical outcomes and major neurological events were observed.Pulsatile flow decreases gaseous micro-bubble filtering properties of oxygenators without integrated arterial filters during CPB. (uniba.it)
  • Results of Laser-Doppler-Anemometry of pulsatile flow in a curved tube of a Newtonian (left) and non-Newtonian (right) shear-thinning fluid representing blood flow in a large artery. (tue.nl)
  • Catheterization increases the mean flow resistance in the arterial blood flow and many other complications are associated with the presence of catheter in the artery. (scirp.org)
  • Effects of catheter in stenosed artery can be estimated non-invasively by means of hemo-dynamic indicator-WSS, WSSG, volume flow rate and impedance. (scirp.org)
  • The effect of slip at the arterial wall, inclination of the artery and magnetic field on the hemodynamic indicators and flow profiles are computed, presented and discussed through graphs. (scirp.org)
  • Sharma, M. , Singh, K. and Bansal, S. (2014) Pulsatile MHD Flow in an Inclined Catheterized Stenosed Artery with Slip on the Wall. (scirp.org)
  • Mekheimer, Kh.S. and El Kot, M.A. (2008) Influence of Magnetic Field and Hall Currents on Blood Flow through a Stenotic Artery. (scirp.org)
  • Ponalgusamy, R. (2007) Blood Flow through an Artery with Mild Stenosis: A Two-Layered Model, Different Shapes of Stenoses and Slip Velocity at the Wall. (scirp.org)
  • To the best of our knowledge, in pulsatile flow, this is the first theoretical study elaborating on hemodynamic factors such as Wall Shear Stress, Oscillatory Shear Index, Relative Residence Time and their effects on the pathogenesis of atherosclerosis by employing BJR slip at the lumen-wall interface, which takes into account the finite wall thickness of the artery. (amrita.edu)
  • Our model can predict the biological response of the artery in the normal/abnormal flow regime in a much better way, if the data fixed are subject specific. (amrita.edu)
  • The unsteady pulsatile flow of blood through porous medium in an artery has been studied under the influence of periodic body acceleration and slip condition by considering blood as incompressible Newtonian electrically conducting fluid in the presence of magnetic field. (scirp.org)
  • Ocular pulse measurements to assess pulsatile blood flow in carotid artery disease. (bmj.com)
  • A hybrid method for investigating pulsatile fluid flow in a long, thin, artery-like tube subjected to external excitations is presented. (strath.ac.uk)
  • In order to investigate the contribution of arterial radius and center-line velocity to the blood conductivity and electrical impedance of pulsatile flow in the human common carotid artery, we proposed three simplified mathematical models to describe the relationship between the center-line velocity, the arterial radius, and the blood conductivity. (springer.com)
  • The open artery hypothesis calls for early, complete, and sustained restoration of blood flow in the culprit epicardial artery in ST-elevation myocardial infarction (STEMI). (onlinejacc.org)
  • For instance, Doppler velocity studies have demonstrated an association between systolic flow reversal in the epicardial coronary artery with dysfunction in the myocardial microvasculature on myocardial contrast echocardiography (2) . (onlinejacc.org)
  • To demonstrate the use of this technique in a clinical context, we have measured blood flow waveforms in a patient immediately before and after percutaneous transluminal angiplasty of a stenosis in the superficial femoral artery. (ucl.ac.uk)
  • The network associated with each main efferent artery of the circle is represented by a single vessel containing an appropriate amount of resistance so that the mean flow through the system is distributed in accordance with the weight of brain irrigated by each vessel as determined from a steady flow model of the same network. (asme.org)
  • The flow patterns revealed that as the degree of stenosis increased, the jet-type flow created by the valve became narrower, and it impinged on the far (distal) wall of the left pulmonary artery further downstream from the junction of the bifurcation. (asme.org)
  • This in turn led to larger regions of disturbed turbulent flow, as well as helical-type secondary flow motions in the left pulmonary artery, compared to the right pulmonary artery. (asme.org)
  • The flow field in the main pulmonary artery also became more disturbed and turbulent, especially during peak systole and the deceleration phase. (asme.org)
  • In the present paper, the magnetohydrodynamics effects on flow parameters of blood carrying magnetic nanoparticles flowing through a stenosed artery under the influence of periodic body acceleration are investigated. (semanticscholar.org)
  • Newer imaging techniques, such as Magnetic Resonance Angiography and Carotid Artery Ultrasonography, have been employed that help determine the site of the problem in the majority of pulsatile tinnitus cases. (tinnitusformula.com)
  • These include aneurysm and arteriovenous malformations, which is an abnormal connection between an artery and a vein.The blood flows directly from a high pressure artery to a lower pressure vein without going through the capillaries. (tinnitusformula.com)
  • We find the ONH experiences continuous oscillatory axial motion that is strongly correlated with simultaneously measured pulsatile blood flow in the central retinal artery. (osapublishing.org)
  • The incidence of acute kidney injury (AKI) after on-pump coronary artery bypass graft (CABG) varies among studies but can be reduced if pulsatile flow is used. (edu.iq)
  • A phantom simulating the exact flow-velocity pulse shape within the common carotid artery is proposed. (ismrm.org)
  • A numerical study of hemodynamic parameters of pulsatile blood flow is presented in a stenotic artery with non-Newtonian models using ADINA. (srttu.edu)
  • The more compliant the artery, the less work a pulsatile heart needs to do and the lower the P needed to pump the blood. (wikibooks.org)
  • 1 Introduction The possibility to predict the flow of blood through natural and artificial vessels has stimulated much research activity in hemodynamics. (witpress.com)
  • Objective To use 4D-flow MRI to characterize hemodynamics of transverse and sigmoid sinus in venous pulsatile tinnitus (PT) patients and to investigate their differences vs healthy controls. (neurology.org)
  • Calculations of pulsatile flow through a branch: implications for the hemodynamics of atherogenesis. (ahajournals.org)
  • Our aim is to compare the effects of the Reynolds and Womersley numbers on the hemodynamics of both sidewall and bifurcations IAs by keeping other parameters, for example, inlet flow waveform and geometry, constant. (hindawi.com)
  • To study these basic aspects of pulmonary capillary hemodynamics, isolated dog lungs were pump perfused alternately by steady flow and pulsatile flow with the mean arterial and left atrial pressures held constant. (elsevier.com)
  • Pulsatile tinnitus (PT) is suspected to be associated with abnormal hemodynamics in sigmoid-sinus. (ismrm.org)
  • During each cardiac cycle pulsatile arterial blood inflates the vascular bed of the brain, forcing cerebrospinal fluid (CSF) and venous blood out of the cranium. (diva-portal.org)
  • Additionally, restricted venous flow from the brain is suggested as the cause of multiple sclerosis. (diva-portal.org)
  • This work focused on assessing the pulsatile waveform of cerebral arterial, venous and CSF flows. (diva-portal.org)
  • Two-dimensional phase contrast magnetic resonance imaging (2D PCMRI) was used to assess the pulsatile waveforms of cerebral arterial, venous and CSF flow. (diva-portal.org)
  • Idiopathic intracranial hypertension is commonly associated with transverse sinus stenosis, a venous cause of pulsatile tinnitus. (ajnr.org)
  • This study may provide more information for diagnosis and treatment of pulsatile tinnitus, especially for patients with PT of venous origin. (ismrm.org)
  • You should certainly consider surgery if your tinnitus is due to a tumor and also if it is due to a venous source (usually pulsatile in this situation). (amazonaws.com)
  • Numerical simulations of pulsatile blood flow through a symmetrical branch modeling the aortic bifurcation were carried out to assess several hemodynamic theories of atherogenesis by comparing the distribution of hemodynamic variables with that of early lesions in arterial branches. (ahajournals.org)
  • The pulsatile flow of incompressible newtonian blood is illustrated by numerical simulations carried out in two saccular aneurism types, a side- and a terminal-aneurism. (numdam.org)
  • Experimental and numerical studies for three-dimensional pulsatile flows are conducted to investigate the flow characteristics in the bifurcated tubes. (koreascience.or.kr)
  • Numerical analyses are focused on the flow patterns for various branch angles ranging from 30.deg. (koreascience.or.kr)
  • Numerical predictions of blood flow patterns and hemodynamic stresses in Abdominal Aortic Aneurysms (AAAs) are performed in a two-aneurysm, axisymmetric, rigid wall model using the spectral element method. (asme.org)
  • Direct numerical simulation of stenotic flows. (cambridge.org)
  • 5] A. T. Golpayeghani, S. Najarian, M. M. Movahedi, "Numerical simulation of pulsatile flow with Newtonian and non-Newtonian behavior in arterial stenosis", Iranian Cardiovascular Research Journal, Vol. 1, No. 3, pp. 167-174, (2008). (srttu.edu)
  • 6] M. Lukacova-Medvidova, A. Zauskova, "Numerical modelling of shear thinning non-Newtonian flows in compliant vessels", International journal for numerical methods in fluids, Vol. 56, No. 8, pp. 1409-1415, (2008). (srttu.edu)
  • Such question is of critical importance to many biological flow phenomena, such as blood past the brain aneurysms and left atrial appendage blood flows. (aps.org)
  • The model corresponds to blood flows through small diameter porous conical vessels. (iospress.com)
  • Choroidal blood flow may be determined by pulsatile ocular blood flow (POBF) measurements. (arvojournals.org)
  • Among PRP-treated subjects with PDR, ocular blood flow was 22% below the control (mean OBF, 619 μL/min), and 34% less than moderate to severe nonproliferative diabetic retinopathy. (arvojournals.org)
  • To evaluate the baseline pulsatile ocular blood flow measurements (POBF) of open-angle glaucoma patients enrolled in a prospective longitudinal study exhibiting focal, diffuse, or sclerotic optic disc phenotypes. (arvojournals.org)
  • Among the baseline measurements performed, patients had their POBF measured in the study eye with the Ocular Blood Flow Tonograph (Orb Diagnostics and Therapeutics, Brooklandville, ML). The average POBF value is automatically calculated by the computer after an observer selected a cluster of at least five regular and uniform ocular pulse curves. (arvojournals.org)
  • These findings, as well as previously reported findings from colour Doppler ultrasound and fluorescein angiography studies, suggest that deficient ocular blood flow is associated with sclerotic optic disc appearance in glaucoma. (arvojournals.org)
  • After 5 min in the seated position POBF measurements were taken with the ocular blood flow (OBF) tonograph. (who.int)
  • A previous study has shown that the pulsatile ocular blood flow (POBF) in eyes with asymmetric age-related macular degeneration (AMD) differs. (elsevier.com)
  • Liu, J. H. / Pulsatile ocular blood flow of choroidal neovascularization in asymmetric age-related macular degeneration after transpupillary thermotherapy . (elsevier.com)
  • Gaw RL, Cornish BH, Thomas BJ (2008) The electrical impedance of pulsatile blood flowing through rigid tubes: a theoretical investigation. (springer.com)
  • Flow waveforms were generated using a programmable pulsatile pump to mimic the heart functions. (aps.org)
  • We have validated the technique using an experimental phantom of blood circulation, consisting of a pump, flexible plastic tubing, the tubular probe of an electromagnetic flowereter (EMF) and a solenoid, to simulate a pulsatile flow waveform, which includes reverse flow. (ucl.ac.uk)
  • The SuperPump is a pulsatile flow pump designed to create advanced cardiac or vascular flow loop systems for simulated use device testing. (protomedlabs.equipment)
  • Pulsatile flow pump applications: heart valve prosthesis testing, hydrodynamic performance testing, stent-graft migration resistance testing, basic flow visualization studies under pulsatile flow, bioabsorbable vascular stent ans scafolds testing, device training and deployment under simulated use conditions. (protomedlabs.equipment)
  • Method and results: In the partial CPB (cardio pulmonary bypass) model (swine), T-PLS (N=6), and Biopump (N=2), a single pulsatile pump (N=2), were compared. (elsevier.com)
  • In the case of single pulsatile flow, during pump systole, pressure increased to 700 - 800 mmHg at the inlet port of the membrane oxygenator. (elsevier.com)
  • We present here the results of mathematical modeling of the process of thrombus formation in the chamber of a blood pump from a pulsatile-type circulation assist system with an output of 30 cm 3 using two types of Russian- made mechanical heart valves. (springer.com)
  • The effects of the type of mechanical heart valve on thrombus formation in the blood pump chamber during operation of the pulsatile-type circulation assist system were assessed. (springer.com)
  • Medvitz, R. B., Development and Validation of a Computational Fluid Dynamic Methodology for Pulsatile Blood Pump Design and Prediction of Thrombus Potential: PhD Thesis, Pennsylvania State University (2008). (springer.com)
  • INCOR is an axial-flow pump for support of the left ventricle. (wikipedia.org)
  • The blood coming from the heart flows into the INCOR axial pump. (wikipedia.org)
  • We aimed to test GMB-filtering properties of three modern oxygenators under pulsatile and non-pulsatile conditions.Seventy-eight patients undergoing on-pump myocardial revascularization were randomized prospectively into three equal groups according to the oxygenator model used during CPB. (uniba.it)
  • A method for operating a peristaltic pump having a molded flow channel contained on an elastomeric sheet that is bonded or mechanically attached to a rigid substrate. (google.com)
  • The pump head rollers are mounted radially from the axis of rotation of the pump motor and compress the elastomeric flow channels against. (google.com)
  • The pump head rollers are mounted radially from the axis of rotation of the pump motor and compress the elastomeric flow channels against the rigid substrate. (google.com)
  • During reflux, the pump head is positioned so that at least one of the rollers compresses the elastomeric flow channel at the input end of the peristaltic pump. (google.com)
  • Gaw RL, Cornish BH, Thomas BJ (2007) Comparison of a theoretical impedance model with experimental measurements of pulsatile blood flow. (springer.com)
  • The measurements were done in steady and pulsatile flow. (iospress.com)
  • Measurements of pulsatile velocity flow were taken at 40 ms intervals, using a tube of 6.6 mm internal diameter and an imaged tube length of 200 mm. (ucl.ac.uk)
  • Calculation of the mean difference and standard deviation of the difference between angiographic velocities and velocities calculated from EMF readings confirmed that the technique was independent of catheter position over this range, but that reduction of tube length resulted in a systematic reduction in mean flow velocity measurements. (ucl.ac.uk)
  • Does the act of doing the measurements also alter the flow? (wholelottarob.com)
  • To enhance our understanding of the flow characteristics past the aortic position of a Jellyfish (JF) valve in the left ventricle, in vitro laser Doppler anemometry (LDA) measurements were carried out under physiological pulsatile flow conditions. (vivitrolabs.com)
  • Note that, P 0 ′ {\displaystyle P'_{0}} (standing for n = 0 {\displaystyle n=0} ) is the steady-state pressure gradient, whose sign is opposed to the steady-state velocity (i.e., a negative pressure gradient yields positive flow). (wikipedia.org)
  • A new and exact solution for flow velocity, blood flow rate and shear force is derived. (nih.gov)
  • Bugliarello, G. and Sevilla, J. (1970) Velocity Distribution and Other Characteristics of Steady and Pulsatile Blood Flow in Fine Glass Tubes. (scirp.org)
  • We simultaneously measured dorsal aortic pressure with a servonull system and flow velocity with a 20-MHz pulsed-Doppler system in stage 24 chick embryos (n=38). (ahajournals.org)
  • Covariance analysis adjusted for age was used to compare average through-plane velocity (V tp_avg ), maximum through-plane velocity (V tp_max ), average velocity (V avg ), maximum velocity (V max ), average blood flow (Flow avg ), and pulsatility index (PI) between PT and control group. (neurology.org)
  • Furthermore, systolic flow reversal on Doppler velocity studies that persists after primary percutaneous coronary intervention (PCI) has also been associated with increased in-hospital mortality (3) . (onlinejacc.org)
  • The shape of the flow velocity waveform was faithfully reproduced but there was an overstimation of peak velocity of 40% at low velocities (peak velocity of 540 mm s-1), reducing to 19% at peak velocities of 964 mm s-1 with an underestimation of 16% at the peak velocities of 1899 mm s-1. (ucl.ac.uk)
  • The flow visualization observations have been valuable in helping to conduct further quantitative studies such as pressure and velocity field mapping. (asme.org)
  • The flow transitioned to turbulence about five diameters away from the stenosis, with velocity spectra taking on a broadband nature, acquiring a -5/3 slope that is typical of turbulent flows. (cambridge.org)
  • Transition was accomplished by the breaking up of streamwise, hairpin vortices into a localized turbulent spot, reminiscent of the turbulent puff observed in pipe flow transition, within which r.m.s. velocity and turbulent energy levels were highest. (cambridge.org)
  • In this study, we used 4D-Flow MRI to characterize blood flow in sigmoid-sinus among patients with pulsatile tinnitus and demonstrated that high blood velocity in sigmoid-sinus might be an authentic marker of PT. (ismrm.org)
  • Therefore, the objective of this study will be to numerically and experimentally investigate the pulsatile turbulent flow downstream of a dysfunctional bileaflet mechanical heart valve in terms of velocity field, vortex formation and potential negative effect on blood components. (elsevier.com)
  • 002 Can non-pulsatile continuous-flow left ventricular assist devices confer physiologically desirable cardiac and physical functional benefits during peak exercise? (bmj.com)
  • A continuous flow left ventricular assist device (c-LVAD) provides a better clinical outcome for patients with severe heart failure than pulsatile flow LVAD (p-LAVD). (ahajournals.org)
  • Patients with advanced heart failure have improved survival rates and quality of life when treated with implanted pulsatile-flow left ventricular assist devices as compared with medical therapy. (thoratec.com)
  • In the HeartMate II Destination Therapy trial, the continuous flow HeartMate II left ventricular assist device did a better job at improving six-minute walk distance, survival and adverse events compared with the pulsatile flow HeartMate XVE left ventricular assist device. (thoratec.com)
  • Flow patterns and wall shear stresses in patient-specific models of the abdominal aortic aneurysm. (imperial.ac.uk)
  • Comparison of heart transplant outcomes between recipients with pulsatile- vs continuous-flow LVAD. (harvard.edu)
  • Most recently it has been shown that the use of continuous-flow LVAD (HeartMate II) improves the rate of survival, quality of life, and functional capacity of patients as compared with the pulsatile-flow LVAD. (bmj.com)
  • Conclusion We have shown for the first time that complementary to reported prognostic benefits, non-pulsatile continuous-flow LVAD pumps can confer cardiac functional benefits to patients with end-stage heart failure to derive improved exercise capacity, while those who recovered sufficiently to allow explantation of LVADs can even achieve cardiac and physical functional capacities nearly equivalent to those of healthy controls. (bmj.com)
  • Continuous flow LVAD decreases cerebral infarction frequency, though ICH frequency remains poor. (ahajournals.org)
  • Careful management of anticoagulation is also required for patients with continuous flow LVAD especially in acute phase of blodd stream infection. (ahajournals.org)
  • Motivated by two-phase microfluidics and by the clinical applications of air embolism and a developmental gas embolotherapy technique, experimental and theoretical models of microbubble transport in pulsatile flow are presented. (biomedsearch.com)
  • Kolin, A. (1936) An Electromagnetic Flowmeter: Principle of Method and Its Application to Blood Flow Acceleration , Experimental Biology and Medicine, 35, 53-56. (scirp.org)
  • This study represents a systematic experimental effort towards pulsatile flow over a standard cavity model, which could serve as a benchmark for future computational simulations. (aps.org)
  • This review on the benefits of pulsatile flow includes not only experimental and clinical data, but also attempts to further illuminate the major factors as to why this debate has continued during the past 55 years. (elsevier.com)
  • Experimental studies indicate that there is a cause-and-effect type of relationship between the pulsatile component of blood pressure and atherosclerotic process. (biomedsearch.com)
  • Comparisons of the analytical predictions and experimental results show that pressures, mass flow rates, and velocities can be predicted with reasonable accuracy for all test conditions employed on the three models. (asme.org)
  • Konig, C. S. and Clark, C., "Flow mixing and fluid residence times in a model of a ventricular assist device," Med. (springer.com)
  • There are many different possible causes of pulsatile tinnitus and different therapies that can be addressed to each type. (tinnitusformula.com)
  • The following section describes some of the more common causes of pulsatile tinnitus and relevant therapies. (tinnitusformula.com)
  • The unsteady flow of blood in a straight arterial segment, driven by an oscillatory pressure gradient, is studied. (witpress.com)
  • The ability to accurately predict the bubble dynamics in unsteady flow within a bifurcating network is demonstrated and suggests the potential for bubbles in microfluidics devices to encode information in both steady and unsteady aspects of their dynamics. (biomedsearch.com)
  • The primary motivation for this dissertation is the fluid flow and structural response to unsteady blood flow in the human body. (wayne.edu)
  • The calculation and modeling of vascular input impedance are based on the assumption that pressure and flow are linearly related in the frequency domain. (ahajournals.org)
  • Pulsatile energy may be a potential promoter of vascular development. (ahajournals.org)
  • Pulsatile pressure-flow relationships are also critical determinants of vascular load that may influence cardiac morphogenesis. (ahajournals.org)
  • The calculation of vascular impedance by Fourier methods and Windkessel-type lumped parameter models is based on the assumption that pressure and flow are linearly related in the frequency domain. (ahajournals.org)
  • Independence of harmonics ensures a unique relationship between corresponding harmonics of pressure and flow and, therefore, justifies the calculation of vascular impedance and hydraulic energy. (ahajournals.org)
  • The direct proof of linearity was obtained in vitro by driving an isolated vascular system with a pure sinusoidal flow input and then determining pulsatile pressure-flow relationships with the use of Fourier analysis. (ahajournals.org)
  • Higher intensities in the CSF and vascular pathways correspond to higher flow velocities. (springer.com)
  • It is sometimes referred to as vascular tinnitus because in the majority of cases, it is related to disturbances in the blood flow. (tinnitusformula.com)
  • The present project aimed to assess cardiac and exercise performance of patients implanted with continuous-flow LVADs under two conditions: (i) optimal device support, and (ii) reduced device support. (bmj.com)
  • The location of the maximum temperature, or hot spot, at the plaque surface can move during the cardiac cycle depending on the arterial geometry and is a direct result of the blood flow pattern. (biomedcentral.com)
  • Conclusion: It is suggested that a portable pulsatile ECLS like T-PLS may be used as a CPB device and as an alternative CPR (cardiopulmonary resuscitation) device in the case of cardiac arrest. (elsevier.com)
  • 3 Steady Flow in Tubes. (nii.ac.jp)
  • Srivastava, V.P. (1996) Two Phase Model of Blood Flow through Stenosed Tubes in the Presence of a Peripheral Layer: Applications, Journal of Biomechanics, 29, 1377-1382. (scirp.org)
  • Comparison of the predicted results with those of a decoupled model demonstrates that it is necessary to consider the mechanism of fluid-structure interaction fully in the study of initially stretched cylindrical tubes conveying pulsatile fluid flow. (strath.ac.uk)
  • Two-phase pulsatile flows through porous conical tubes of small diameters. (iospress.com)
  • The simulations that were performed represent a major advance over prior attempts to simulate pulsating flows in flexible- and rigid-walled tubes. (wayne.edu)
  • Flow characteristics of Newtonian fluid and blood in the bifurcated tubes under the steady and pulsatlie flows are numerically investigated. (koreascience.or.kr)
  • Comparisons with a steady-flow calculation at the same mean flow rate showed that the severity of all of these proposed hemodynamic determinants was increased by pulsatility. (ahajournals.org)
  • A comparison between predictions for steady and pulsatile flow is presented, illustrating the importance of considering time-dependent flow for the evaluation of hemodynamic indicators. (asme.org)
  • With advances both in monitoring technologies and data analysis capabilities, we now have the capacity to capture dynamic changes in patient status by recording and analyzing non-invasive, high frequency hemodynamic waveform data, including ECG, arterial pressure, and most recently, cerebral blood flow and oxygenation. (frontiersin.org)
  • Among the hemodynamic factors, vortical structures determine the complexity and stability of the flow pattern in an IA dome, which plays an important role in the rupture of IAs [ 3 , 5 - 7 ]. (hindawi.com)
  • 11. The method of claim 1 wherein the arterial hemodynamic behavior data comprises pulse flow wave data. (google.com.au)
  • Magnetic resonance imaging (MRI) was used to evaluate cerebrospinal fluid (CSF) pulsatile flow in eleven patients with hydrocephalus and three normal subjects. (springer.com)
  • The (1 3 3 1) sequence was found to be a good compromise between competing design criteria, and its application to viewing pulsatile cerebrospinal fluid motion is described. (elsevier.com)
  • Wayte, SC , Redpath, TW & Beale, DJ 1992, ' Magnetic resonance imaging of pulsatile cerebrospinal fluid flow by spatial modulation of magnetization ', British Journal of Radiology , vol. 65, pp. 495-501. (elsevier.com)
  • In patients with idiopathic intracranial hypertension, CSF drainage via lumbar puncture decreases intracranial pressure, which relieves the stenosis, and may provide at least temporary cessation of pulsatile tinnitus. (ajnr.org)
  • 2. A resting part (where V of blood flowing decreases to 0. (wikibooks.org)
  • These findings suggest that TTT decreases the pulsatile choroidal blood flow in eyes with CNV in patients with asymmetric AMD and the effects persist for 2 months. (elsevier.com)
  • Such studies are of particular importance because there is indirect evidence that the causes and developments of many cardiovascular diseases are, to a great extent, related to the characteristics of blood flow, such as the high values of the shear stress at the wall or its variations [l]-[3]. (witpress.com)
  • Its action increases pulsatile shear stress (PSS) to the endothelium such that the bioavailability of nitric oxide (NO) and other mediators are increased throughout the body. (portlandpress.com)
  • By increasing pulsatile shear stress (PSS) to the endothelium, the bioavailability of nitric oxide (NO) and other mediators are increased to provide treatment of complications of COVID-19 and potential inhibition of SARS-CoV-2 replication. (portlandpress.com)
  • At peak flow, the highest shear stress and WSSG levels are obtained downstream of both aneurysms, in a pattern similar to that of steady flow. (asme.org)
  • Maximum values of wall shear stresses and wall shear stress gradients obtained at peak flow are evaluated as a function of the time-average Reynolds number resulting in a fourth order polynomial correlation. (asme.org)
  • The acceleration of the fluid through the stenosis resulted in wall shear stress (WSS) magnitudes that exceeded upstream levels by more than a factor of 30 but low WSS levels accompanied the flow separation zones that formed immediately downstream of the stenosis. (cambridge.org)
  • Using computation fluid dynamics combined with CT images, the flow patterns and wall shear stress (WSS) in the AAA of a patient were studied. (imperial.ac.uk)
  • Flow rates of 2 mL/sec, representative of flow through small diameter blood vessels, can be generated, resulting in a mean wall shear stress of similar to 6 dynes/cm(2) within the 3 mm ID constructs. (duke.edu)
  • Pulsatile flow characteristics of blood are compared with those of Newtonian fluid. (koreascience.or.kr)
  • On Pulsatile, Non-Newtonian Flow in the Microcirculation. (rand.org)
  • Also, in maximum flow rate, the Carreua, generalized Power Law, Casson, and Carreua-Yasuda models showed a reduction in global importance factor of non-Newtonian behavior, and as a result, the results approached Newtonian model. (srttu.edu)
  • In minimum flow rate, the global importance factor of Newtonian behavior increased, which highlighted the importance of Newtonian model. (srttu.edu)
  • In minimum flow rate, Carreua-Yasuda model was more sensitive to the non-Newtonian behavior of blood compared to Carreua, Casson, and Power Law models. (srttu.edu)
  • Results Pulsatile flow (systolic flow reversal with cessation of antegrade contrast-dye motion or frank reversal of contrast-dye motion during systole) at 60 min after fibrinolytic administration was present in 11.0% of patients. (onlinejacc.org)
  • Patients with pulsatile flow had a higher risk of death or reinfarction at 30 days (10.3% vs. 5.0%, p = 0.019). (onlinejacc.org)
  • By determining pulsatile outflow we have the potential to achieve new diagnostic and treatment options for our patients. (wholelottarob.com)
  • Patients who are pregnant, anemic, or have thyroid problems, may develop increased blood flow through the jugular vein, the largest vein in the neck. (tinnitusformula.com)
  • The aim of this study was to describe the results of using paracorporeal pulsatile-flow VADs as a bridge to transplant (BTT) in adult patients. (revespcardiol.org)
  • The aim of this study is to evaluate pulsatile flow impact on renal function of elderly patients undergoing CABG. (edu.iq)
  • However, the pulsatile tinnitus (PT) patients were excluded in previous studies because of the totally different mechanisms of the two subtype tinnitus. (hindawi.com)
  • Q-PULS, a new quasi-physiological pulsatile extracorporeal model to simulate heart function. (harvard.edu)
  • Sfriso R, Zhang S, Bichsel CA, Steck O, Despont A, Guenat OT, Rieben R. 3D artificial round section micro-vessels to investigate endothelial cells under physiological flow conditions. (harvard.edu)
  • The overall aim of this dissertation was to explore cerebral blood flow and intracranial pulsatility using MRI, with respect to measurement, physiological and pathophysiological aspects. (diva-portal.org)
  • Most long-term ventricular assist devices (VADs) that are currently implanted are intracorporeal continuous-flow devices. (revespcardiol.org)
  • New continuous-flow devices are smaller and may be more durable than the pulsatile-flow devices. (thoratec.com)
  • Rhythmic, intermittent propagation of a fluid through a BLOOD VESSEL or piping system, in contrast to constant, smooth propagation, which produces laminar flow. (harvard.edu)
  • Microbubble transport through a bifurcating vessel network with pulsatile flow. (biomedsearch.com)
  • the highest values occurred at the convex corner on the outer wall of the branch and in the neighborhood of the flow divider tip, and the lowest shears were experienced by the outer wall of the daughter vessel a short distance distal to the corner. (ahajournals.org)
  • Transient flow reversal occurred almost everywhere in the branch, and a transient separated region was found corresponding to the low-shear region in the daughter vessel. (ahajournals.org)
  • Within regions of circulatory system, the flow is pulsatile as a function of vessel proximity to the heart as well as the geometry and health of the vessel leading to variable regional shear loading. (fluxionbio.com)
  • This results from either increased blood flow or a narrowing of the opening of the blood vessel, both of which result in turbulent blood flow that can be heard in the ears. (tinnitusformula.com)
  • In a pioneering study, Stump et al have shown that a Dacron patch suspended in the flow, without contact with the vessel wall, was covered with endothelial colonies within 7 days of implantation. (ahajournals.org)
  • The introduction of a geometric perturbation within the current model, in the form of a stenosis eccentricity that was 5% of the main vessel diameter at the throat, resulted in breaking of the symmetry of the post-stenotic flow field by causing the jet to deflect towards the side of the eccentricity and, at a high enough Reynolds number of 1000, jet breakdown occurred in the downstream region. (cambridge.org)
  • Murray's derivation of this relationship assumed that there is an energy requirement for producing the blood contained in a vessel that is proportional to the volume of blood in a vessel and that there is an energy requirement for pumping blood through a vessel that is given by Poiseuille's Law for flow in a tube. (biomedcentral.com)
  • 2 Equations of Fluid Flow. (nii.ac.jp)
  • An initially axially stretched elastic tube conveying pulsating fluid, simply supported at both ends, is modelled to assess the effect of external harmonic excitation on the dynamic responses of the tube and the fluid flow. (strath.ac.uk)
  • wherein rotating the roller head to cause fluid flow comprises rotating the roller head so that the roller head contacts the raised portion of the sheet to cause fluid flow through the at least one fluid channel. (google.com)
  • However, bubble lodging was affected by the flow pulsatility, and the effects of pulsatile flow were evident in the dependence of splitting ratio of bubble length. (biomedsearch.com)
  • We assessed the agreement regarding net flow and the volume of arterial pulsatility (V) for all vessels. (diva-portal.org)
  • However, how the flow pulsatility affects the vortex dynamics of the cavity flow is still not fully understood. (aps.org)
  • Aqueous outflow drugs increase the outflow pulsatility, not just flow. (wholelottarob.com)
  • In fluid dynamics, a flow with periodic variations is known as pulsatile flow, or as Womersley flow. (wikipedia.org)
  • When compared to corresponding constant flow, pulsatile flow was shown to produce insignificant changes to the overall splitting ratio of the bubble despite the order one Womersley numbers, suggesting that bubble splitting through the vasculature could be modeled adequately with a more modest constant flow model. (biomedsearch.com)
  • An analysis of these coupling effects is presented for Womersley numbers α = 2.81 and 3.97 and a mean flow Reynolds number Re = 875. (strath.ac.uk)
  • Reynolds and Womersley numbers (explained in Section 3 ) are the only two nondimensional parameters required for full dynamic similarity in pulsatile internal flows [ 15 ]. (hindawi.com)
  • In fact, Jiang and Strother [ 16 ] concluded that increase of Womersley number can significantly increase the complexity of the flow pattern and vortex structures in two patient-specific intracranial aneurysms based on their CFD simulations. (hindawi.com)
  • 17 ] stated that Womersley number does not affect the flow feature and structures based on their CFD simulations of an IA from a rabbit. (hindawi.com)
  • Specifically, it should be possible to derive the law from the basic work of Womersley on pulsatile flow in an elastic tube [ 6 ]. (biomedcentral.com)
  • Therefore, we investigated the linearity of pulsatile pressure-flow relations in vivo with acute alterations in cycle length. (ahajournals.org)
  • To determine if training and acute exercise influence the neuroendocrine regulation of the HPG axis in men we examined pulsatile LH release in six male endurance runners with a training volume of at least 80 km per week, and compared this with values in six age-matched sedentary controls. (nih.gov)
  • For α ≲ 2 {\displaystyle \alpha \lesssim 2} , viscous forces dominate the flow, and the pulse is considered quasi-static with a parabolic profile. (wikipedia.org)
  • After controlling for age, pulse, blood pressure, anterior MI location, epicardial flow, and creatine kinase, pulsatile flow remained associated with an increased risk of death/MI (odds ratio 3.1, p = 0.006). (onlinejacc.org)
  • This may result in a vicious circle wherein the pulsatile blood pressure component induces/enhances the development of atherosclerosis, which in its turn reduces the arterial compliance and enhances pulse wave reflection, thereby leading to an increase in PP. Currently new drug classes are being investigated, which might reduce the pulsatile blood pressure component without changing mean blood pressure level. (biomedsearch.com)
  • These data provide the first direct account of how the pulmonary capillaries respond to pulsatile flow by showing that capillaries are recruited during the systolic pulse and that, once open, the capillaries remain open throughout the pulsatile cycle. (elsevier.com)
  • Introduction: T-PLS (Twin-Pulse Life Support) is the first commercial pulsatile ECLS (Extra Corporeal Life Support) device (1). (elsevier.com)
  • The jugular vein traverses the middle ear and any turbulent flow in the vein can be heard in the middle ear as a "hum" which may or may not fluctuate with the pulse. (tinnitusformula.com)
  • That is, the flow is continuous and at constant pressure, the systolic and diastolic being equal and pulse pressure being zero. (stackexchange.com)
  • We report that coordinate pulsatile insulin secretion is reestablished in islet transplant recipients and that glucose-mediated stimulation of insulin secretion is accomplished by amplification of insulin pulse mass. (diabetesjournals.org)
  • It was found that the pulsation promoted the different mechano-transduction process from that of the steady flow. (elsevier.com)
  • The steady flow results are examined here while the pulsatile flow analysis is dealt with in Part 2 of this study. (cambridge.org)
  • 5 Pulsatile Flow in an Elastic Tube. (nii.ac.jp)
  • To determine the implications of the constant shear force hypothesis and to extend Murray's energy cost minimization to the pulsatile arterial system, a model of pulsatile flow in an elastic tube is analyzed. (nih.gov)
  • An analytical study is presented for one-dimensional, pulsatile flow of an incompressible fluid in systems of elastic tubing. (asme.org)
  • 4. The integrated flow controller module according to claim 3 further comprising an orifice in said fluid channel adjacent to said pressure sensor and a closed pressure cavity external to said elastic wall, adjacent to said resistor layer. (google.ca)
  • 6. The integrated flow controller module according to claim 3 wherein said elastic semiconductor membrane and said elastic wall element are connected. (google.ca)
  • The existence of the free shear layer causes variations of vortex structures and flow stagnations inside the cavity in different flow regimes. (aps.org)
  • Phase-locked PIV were conducted to study the cyclic variation of vortex flow structures inside and across the cavity. (aps.org)
  • The vortex dynamics induced by pulsatile flow in AAAs is characterized by a sequence of five different flow phases in one period of the flow cycle. (asme.org)
  • The results show that the flow downstream of a dysfunctional valve was characterized by abnormally elevated velocities and shear stresses as well as large scale vortices. (elsevier.com)
  • In this episode, I talk with Murray Johnstone from Seattle about pulsatile flow through the Trabecular Meshwork and collector channels. (wholelottarob.com)
  • A discussion about Pulsatile Flow through the trabecular meshwork and collector channels with Murray Johnstone. (wholelottarob.com)
  • I sat down with Murray Johnstone at a recent American Glaucoma Society meeting to discuss Pulsatile Flow through the trabecular meshwork and collector channels of the eye. (wholelottarob.com)
  • 1.9 Laminar and Turbulent Flow. (nii.ac.jp)
  • Regulation of Yes-Associated Protein by Laminar Flow. (harvard.edu)
  • In particular, a flow initiated in a relatively large upstream cross section may be laminar based on inlet conditions. (wayne.edu)
  • It occurs when the normally smooth laminar flow of blood is disturbed. (tinnitusformula.com)
  • At inlet Reynolds numbers of 500 and 1000, DNS predict a laminar flow field downstream of an axisymmetric stenosis and comparison to previous experiments show good agreement in the immediate post-stenotic region. (cambridge.org)
  • Blood flow was considered laminar, and arterial wall was considered rigid. (srttu.edu)
  • Pulsatile Flow Investigation in Development of Thoracic Aortic Aneurysm: An In-Vitro Validated Fluid Structure Interaction Analysis. (vivitrolabs.com)
  • AAA geometry was obtained from images acquired during a routine CT scan, and a realistic abdominal aortic flow waveform was used as an upstream boundary condition. (imperial.ac.uk)
  • One such origin suggested in literature is the impedance variation induced by changes in red blood cell orientation during pulsatile blood flow. (springer.com)
  • K. R. Visser (1989) Electric properties of flowing blood and impedance cardiography. (springer.com)
  • P. M. de Vries, J. W. Langendijk and P. M. Kouw (1995) The influence of alternating current frequency on flow related admittance changes of blood: a concept for improvement of impedance cardiography. (springer.com)
  • Raaijmakers E, Marcus JT, Goovaerts HG, De Vries PMJM, Faes TJC, Heethaar RM (1996) The influence of pulsatile flow on blood resistivity in impedance cardiograp. (springer.com)
  • 4 Pulsatile Flow in a Rigid Tube. (nii.ac.jp)
  • Goldmann thought the TM was rigid preventing he and Asher from being able to explain the pulsatile nature of the flow. (wholelottarob.com)
  • In order to gain more insight on TAA formation, we developed a computational framework in vitro to investigate and compare the flow patterns between pre-aneurismal and post-aneurismal aorta using a deformable wall model. (vivitrolabs.com)
  • It is important to investigate all instances of pulsatile tinnitus. (tinnitusformula.com)
  • Hence, it is important to investigate the flow field downstream of a dysfunctional mechanical heart valve to better understand its impact on blood components (red blood cells, platelets and coagulation factors) and to improve the current diagnosis techniques. (elsevier.com)
  • All visualization, quantification, and analysis of 4D-flow data were performed using dedicated software. (neurology.org)
  • It can be easily integrated to existing test benches and provide extra capabilities for testing ie - migration resistance testing, basic flow visualization studies under pulsatile flow, bioresorbable scaffolds, device training and deployment under simulated use conditions. (protomedlabs.equipment)
  • Medications that enhance aqueous outflow in glaucoma in fact improves the pulsatile stroke volume. (wholelottarob.com)
  • This selection ignored the fact that flowing fluids passing through variable cross sections undergo changes of flow regime. (wayne.edu)
  • Some studies have suggested that the pulsatile pattern of insulin delivery to the liver is important in insulin action ( 11 , 12 ). (diabetesjournals.org)
  • In conclusion, intrahepatic islet transplantation effectively restores the liver to pulsatile insulin delivery. (diabetesjournals.org)
  • A theoretical study concerning two-component fluid pulsating flow through porous conical ducts is presented. (iospress.com)
  • In this study, we designed and characterized a fiber-based laser speckle imaging system to study pulsatile blood flow in the tooth. (nih.gov)
  • A presentation of the most elementary form of pulsatile flow as an important prerequisite for the study of other flow applications in biological systems. (nii.ac.jp)
  • The goal of this study is to reveal the flow characteristics of two simple rectangular sidewall cavity models under physiologically-relevant pulsatile flow. (aps.org)
  • In persons with pulsatile tinnitus, additional tests may be proposed to study the blood vessels and to check the pressure inside the head. (amazonaws.com)
  • Computer results are given as time histories of pressure and flow at any model nodal point starting from initial conditions of null flow and constant pressure throughout the model. (asme.org)
  • Variations in these pressure and flow distributions caused by the introduction of pathologic situations into the model illustrate the efficacy of the simulation and of the circle in equalizing and redistributing flows in abnormal situations. (asme.org)
  • Of special relevance is that the capability to simulate the proper flow regime enabled a more realistic response of the bounding wall of the tube to the imposed pulsations. (wayne.edu)