Chronotropic doses of dobutamine have been shown to increase transmural WT, even in perfusion beds subtended by coronary stenoses that range from 30% to 80% in diameter (8). If the stenosis is more severe or if higher doses of dobutamine are used, WT becomes abnormal (2). Transmural myocardial blood flow responses, however, are different, with decreases in myocardial blood flow observed even in milder non-flow limiting stenoses (2). As the stenosis becomes more severe, a marked decrease in subendocardial blood flow has been observed (9-11), with a marked decrease in endocardial/epicardial flow ratios. In this study, RTMCE detected this decrease in endocardial to epicardial blood flow abnormality in 45 of the 55 patients with LAD stenoses ,50%.. Another pertinent pharmacologic property of dobutamine is its ability to recruit the subepicardial layers to thicken. The subendocardium is responsible for over 40% of WT under resting conditions (12,13), and thus resting WT might be abnormal even when ...
Background. Experimental studies on the effects of alpha2-adrenoceptors on regional coronary blood flow in normal and ischemic myocardium are highly controversial. A beneficial effect on regional ischemic myocardium has been demonstrated in different animal preparations with either alpha2-adrenoceptor blockade or stimulation. Animal studies also demonstrated that postsynaptic alpha2-adrenoceptors mediate vasoconstriction in coronary and femoral vascular beds. The aims of the study were 1) to investigate the effects of regional alpha2-adrenoceptor stimulation on regional coronary blood flow in subjects with angiographically normal coronary arteries, 2) to assess the effect of alpha2-adrenoceptor blockade on coronary circulation in control subjects, and 3) to examine the influence of atherosclerosis on coronary blood flow response to alpha2-adrenoceptor blockade. Methods and Results. The effect of regional administration of BHT 933 (a selective alpha2-adrenoceptor agonist) was studied in eight ...
Previous reports have indicated that hypertensive patients who have angina-like chest pain and normal coronary arteriograms have reduced coronary flow velocity reserve (CFVR) levels. In addition, elevated plasma endothelin-1 (ET-1) levels have been reported to be associated with microvascular angina. The purpose of this study was to evaluate the plasma ET-1 levels and CFVR in patients with chest pain but without coronary artery disease (CAD). A total of 66 patients were included in this study. CAD was ruled out by exercise stress test or coronary angiogram. Plasma ET-1 and CFVR measurements were performed in patients with (n=35) and without (n=31) a history of angina-like chest pain. CFVR was measured using adenosine-triphosphate stress transthoracic Doppler echocardiography. The mean ET-1 level was significantly higher and the CFVR was significantly lower in patients in the symptomatic group than in those in the asymptomatic group (ET-1: 3.85±1.24 pg/ml vs. 2.98±1.27 pg/ml, CFVR: 2.26±0.48 vs. 2.77
Coronary flow velocity reserve (CFVR) measured by transthoracic Doppler echocardiography of the LAD is used to assess microvascular function but validation studies in clinical settings are lacking. We aimed to assess feasibility, reproducibility and agreement with myocardial flow reserve (MFR) measured by PET in overweight and obese patients. Participants with revascularized coronary artery disease were examined by CFVR. Subgroups were examined by repeated CFVR (reproducibility) or Rubidium-82-PET (agreement). To account for time variation, results were computed for scans performed within a week (1-week) and for all scans regardless of time gap (total) and to account for scar tissue for patients with and without previous myocardial infarction (MI). Eighty-six patients with median BMI 30.9 (IQR 29.4-32.9) kg × m−2 and CFVR 2.29 (1.90-2.63) were included. CFVR was feasible in 83 (97 %) using a contrast agent in 14 %. For reproducibility overall (n = 21) limits of agreement (LOA) were (−0.75;0.71),
The effect of a new coronary vasodilator (Persantin), which produces a marked increase in coronary blood flow (up to 159 per cent in normal animals) without increasing cardiac contractility or cardiac work, has been studied in the experimental animal. This is associated with a marked decrease in coronary resistance. There is an increase in the coronary venous oxygen content and a decrease in the coronary A-V oxygen difference; the cardiac output is only slightly affected. Increase in the coronary blood flow has also been observed in dogs in which coronary in sufficiency has been produced by coronary ligation and by narrowing of the lumen of the coronary artery by the application of casein rings. This was accompanied by no significant increase in cardiac work.. ...
Relief of the coronary obstruction by thrombolysis or percutaneous catheter-based intervention and restoration of normal flow in the culprit artery has been the goal of therapy in patients with acute MI. This analysis shows, however, that acute MI slows flow not only in the culprit artery, but also in the nonculprit artery by 45%. Culprit and nonculprit artery flows were linked, and relief of the residual stenosis in the culprit artery restored flow to the culprit artery, which was the same as in the nonculprit arteries (both 30 frames). Although improved post-PTCA, both culprit and nonculprit artery flows were still 45% slower than normal (21 frames). Multiple variables were associated with slower nonculprit artery flow: slower flow in the associated culprit artery, a larger territory infarcted (e.g., larger diameter culprit arteries with a larger percent of the culprit vessel distal to the stenosis, the absence of collaterals, LAD as the culprit artery), tighter stenoses within the nonculprit ...
To examine the influence of preexistent diabetes mellitus on left ventricular performance and coronary blood flow responses to acute ischemia, mild normoglycemic diabetes was induced in nine mongrel dogs after three doses of alloxan, (20 mg/kg, iv), at monthly intervals. Hemodynamic measurements and coronary blood flow (85Kr clearance) were obtained before and after the onset of ischemia. This was produced by occlusion of the proximal left anterior descending coronary artery via a balloon-type catheter in nine intact anesthetized diabetic dogs and 10 nondiabetic dogs. During the 1st hour of ischemia in the diabetic group, the end-diastolic pressure rose from 7 +/- 1.1 (mean +/- SE) mm Hg to 23.8 +/- 2.3 without a significant increase of end-diastolic volume. In controls end-diastolic pressure rose from 8.6 +/- 1.1 mm Hg to 15.3 +/- 1.4, and end-diastolic volume was significantly increased, so that the ratio of end-diastolic pressure and volume was significantly higher in the diabetic group (P ...
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Apart from evaluating the physiological significance of epicardial stenoses, intracoronary Doppler has become an important tool in patients with suspected microvascular disease. Recent studies report an impaired coronary flow reserve in patients with diabetes mellitus, hypertension and smoking (11,19-22). These findings are attributed to abnormalities in coronary vasomotion. It has been proposed that a coronary flow reserve of less than 2.5 (23) and a CFVR of less than 2.24 (14) in the absence of significant epicardial stenosis is a sign of microvascular dysfunction. Categorizing women in this study according to the cut-off value for CFVR of 2.24 revealed that women with suspected microvascular dysfunction have a significantly increased bAPV, and systolic blood pressure. As these factors may, in part, contribute to the reduction of CFVR, the use of traditional CFVR as an indicator of microvascular dysfunction may not sufficiently discriminate between factors affecting vasodilator reserve and ...
article{2286a0f7-5934-41f8-aed8-94b7a8b75a40, abstract = {Recent studies indicate a severely reduced coronary flow reserve (CFR) in neonates with congenital heart disease. The significance of these studies remains debatable, as the ability of the anatomically normal neonatal heart to increase coronary flow is currently unknown. This study was designed to establish normal values for CFR in newborns after administration of adenosine [pharmacologic CFR (pCFR)] and as induced by acute hypoxemia (reactive CFR). Thirteen mechanically ventilated newborn lambs were studied. Coronary flow velocities were measured in the proximal left anterior descending coronary artery before and after adenosine injection (140 and 280 mug/kg i.v.) using an intracoronary 0.014-in Doppler flow-wire. Measurements were made at normal oxygen saturation (Sao(2)) and during progressive hypoxemia induced by lowering the fraction of inspired oxygen. CFR was defined as the ratio of hyperemic to basal average peak flow velocity. In ...
C Newman, D Hackett, H El-Tamimi, A Maseri, G Davies; Acetylcholine Has Dose-Dependent Bimodal Effects on Coronary Blood Flow in Man. Clin Sci (Lond) 1 January 1988; 74 (s18): 45P. doi: https://doi.org/10.1042/cs074045P. Download citation file:. ...
5-hydroxytryptamine (5-HT)-induced coronary artery responses have both vasoconstriction and vasorelaxation components. The vasoconstrictive effects of 5-HT have been well studied while the mechanism(s) of how 5-HT causes relaxation of coronary arteries has been less investigated. In isolated rat hearts, 5-HT-induced coronary flow increases are partially resistant to the nitric oxide synthase inhibitor Nω-Nitro-L-arginine methyl ester (L-NAME) and are blocked by 5-HT7 receptor antagonists. In the present study, we investigated the role of 5-HT7 receptor in 5-HT-induced coronary flow increases in isolated rat hearts in the absence of L-NAME, and we also evaluated the involvement of endothelium-derived hyperpolarizing factor (EDHF) in 5-HT-induced coronary flow increases in L-NAME-treated hearts with the inhibitors of arachidonic acid metabolism and the blockers of Ca2+-activated K+ channels. In isolated rat hearts, 5-HT and the 5-HT7 receptor agonist 5-carboxamidotryptamine induced coronary flow
Myocardial perfusion imaging (MPI), using single photon emission computed tomography (SPECT) is a validated method for detecting coronary artery disease. Transthoracic Doppler echocardiography (TTDE) of flow at rest and during adenosine provocation has previously been evaluated in selected patient groups. We therefore wanted to compare the diagnostic ability of TTDE in the left anterior descending coronary artery (LAD) to that of MPI in an unselected population of patients with chest pain referred for MPI. Our hypothesis was that TTDE with high accuracy would identify healthy individuals and exclude them from the need for further studies, enabling invasive investigations to be reserved for patients with a high probability of disease. Sixty-nine patients, 44 men and 25 women, age 61 ± 10 years (range 35-82), with a clinical suspicion of stress induced myocardial ischemia, were investigated. TTDE was performed at rest and during adenosine stress for myocardial scintigraphy. We found that coronary flow
This study was designed to examine the relationship between epicardial ST change (EpST) and regional myocardial blood flow (RMBF) following coronary occlusion and extent of myocardial infarction (MI) in awake dogs. Fifteen min and two hr after coronary occlusion simultaneous measurements of EpST and RMBF were made. Six days later histologic MI and RMBF were determined in transmural myocardial samples from each electrode site. Greatest ST elevation occurred at sites of greatest ischemia and MI. However, 15 min after occlusion 29% of sites with greater than 50% MI and 39% of sites with greater than 50% reduction in RMBF did not demonstrate ST elevation greater than 2 mV. There were poor correlations between EpST and MI (r = 0.59) and RMBF (r = 0.57). Comparable relationships were observed two hr after occlusion. In the present study, there were not close quantitative or qualitative relationships between EpST and MI or RMBF. A good correlation was observed between RMBF at two hr and MI (r = 0.89). ...
There is intense controversy as to the mechanisms underlying chronic but reversible left ventricular (LV) ischemic dysfunction. The aim of this study was to investigate the physiology underlying this condition in a canine model of noninfarcted collateral-dependent myocardium. METHODS: Six mongrel dogs were instrumented with ameroid constrictors on the left circumflex and right coronary arteries and a partial occluder on the left anterior descending coronary artery. The animals were followed up for 6 mo. Every 6 wk, measurements of regional wall thickening (M-mode echo), myocardial blood flow ((13)N-ammonia PET), oxygen consumption ((11)C-acetate PET), and glucose uptake ((18)F-FDG PET) were obtained. After 6 mo, myocardial blood flow reserve (during adenosine infusion) and regional contractile reserve (during infusion of a low dose of dobutamine) were also investigated. RESULTS: Following ameroid implantation, regional thickening decreased in the posterior wall (to 34% +/- 13% of baseline; P , ...
Spontaneously hypertensive rats (SHR) demonstrate an elevated minimal coronary vascular resistance by the seventh month of age. In an attempt to determine the role of long-standing hypertension in the etiological process of the elevated minimal coronary vascular resistance, we treated SHR and normotensive Wistar-Kyoto rats (WKY) with the vasodilator hydralazine from the time of weaning (1 month) until they were 7 to 8 months of age. The animals were instrumented 24 hours after their last drug dose and then studied on the following day. Using microspheres we measured myocardial perfusion in conscious rats at rest and during maximal coronary dilation induced with dipyridamole infusion. Hydralazine maintained arterial blood pressures in the normotensive range throughout the experimental period, but had little effect on left ventricular weight/body weight ratios (control SHR = 2.95 +/- 0.07, treated SHR = 2.73 +/- 0.08, control WKY = 2.39 +/- 0.09, mean +/- SEM). In treated SHR, left ventricular ...
TIMI frame count is an alternative to the TIMI flow. Unlike TIMI flow, it offers a quantitative assessment of coronary artery blood flow. TIMI frame count is expressed as the number of frames required for dye to reach a standardized distal landmark in a coronary artery.
The results of the present study confirm previous observations that relate elevated WBC count to adverse clinical outcomes in patients with acute MI and further explore the pathophysiology that underlies this relationship. Several new important observations were made. First, an elevation in WBC count was associated with a resistance to thrombolytic therapy as demonstrated by lower rates of coronary patency at both 60 and 90 minutes after the administration of thrombolytic therapy, as well as an increased thrombus burden in patients with a patent infarct-related artery. This was independent of duration of symptoms, which has also been associated with thromboresistance. Second, elevations in WBC count were associated with impaired microvascular perfusion as demonstrated by a reduction in myocardial perfusion grade. Third, elevation in WBC count was a strong predictor of the subsequent development of CHF independent of epicardial or microvascular coronary blood flow.. In the present study, an ...
The first aim of this thesis was to critically appraise and improve the classification of small cerebellar infarctions and to visualise arterial cerebellar perfusion territories. Although small cerebellar infarcts are traditionally classified into "watershed" or "border zone" perfusion territories, arterial perfusion territories and the border zones in between them are widely variable among subjects. Also, many infarcts do not fit into such a classification system, which hinders its use in clinical practice [1].. We proposed two answers to these limitations. The first was to omit the traditional classification and to classify small cerebellar infarctions according to anatomical location in the cerebellum instead of arterial perfusion territories [1]. The second and more challenging answer was to develop the first imaging technique to visualise cerebellar perfusion territories in vivo [2]. This way, cerebellar infarction may be directly linked with the responsible diseased artery, for instance, ...
TY - JOUR. T1 - Importance of basal nitric oxide synthesis in regulation of myocardial blood flow. AU - Benyó, Zoltán. AU - Kiss, Gergely. AU - Szabo, Csaba. AU - Csáki, Csilla. AU - Kovách, Arisztid G.B.. PY - 1991/1/1. Y1 - 1991/1/1. N2 - Study objective - The aim was to investigate whether basal coronary vascular tone and myocardial perfusion depend upon endothelial nitric oxide (NO) synthesis.Design - Myocardial blood flow and vascular resistance of the left and right ventricles were studied before and after intravenous infusions of either NG-nitro-L-arginine (L-NA), a specific inhibitor of NO synthase, or L-arginine, the precursor of NO synthesis. Radiolabelled microspheres were used to study myocardial blood flow in small tissue sections.Experimental material - 14 anaesthetised male cats, weight 2.1-3.5 kg, were used.Measurements and main results - Measurements were made before and 15 and 40 min after L-NA treatment (30 mg·kg-1 bolus followed by 1 mg·kg-1·min-1 infusion; n=8), and ...
BACKGROUND: Positron emission tomography scanners with retractable septa allow both 3-dimensional (3D) and 2-dimensional (2D) acquisition modes. The study aim was to directly compare 2D and 3D acquisition modes for the evaluation of absolute myocardial blood flow (MBF) over a wide range of flow values. METHODS AND RESULTS: Instrumentation was used in 4 dogs to reduce the left circumflex artery lumen by greater than 75%. During infusion of adenosine, MBF was measured with both 2D and 3D dynamic acquisition and both oxygen 15 water and nitrogen 13 ammonia. Injected activities were 333 MBq and 111 MBq for 2D acquisition and 3D acquisition, respectively. Data were reconstructed by analytic methods, and MBF was assessed by use of an 18-segment model. MBF values ranged from 0.4 to 5.8 mL x g(-1) x min(-1) with O-15 water and from 0.3 to 3.9 mL x g(-1) x min(-1) with N-13 ammonia. No significant differences were observed in absolute MBF values obtained with the 2 acquisition modes, regardless of the ...
Assess the effect of Ticagrelor compared to placebo on the adenosine induced coronary blood flow velocity response by estimating the change in area under the adenosine dose response curve before and after study drug. [ Time Frame: During 6 h at visit 2 ...
p,The effect of the heart rate and myocardial contractile force on the extravascular resistance to blood flow of the left anterior descending coronary artery (LAD) was evaluated in 15 mongrel dogs anesthetized with sodium pentobarbital. The LAD was maximally dilated by intracoronary infusion of adenosine, which precluded the influence of vasomotor tone. Increases in the heart rate and myocardial contractile force decreased coronary blood flow in the absence of a change in coronary perfusion pressure. The changes in mean coronary resistance showed a significant linear relationship to changes in developed tension. The changes in coronary resistance caused by varying the heart rate and contractile force were so small that a normal coronary vascular tree could easily compensate for the increase in resistance. However, it is supposed that with critical stenosis of the vascular tree even a small increase in resistance might cause deleterious effects on coronary blood flow.,/p, ...
The effects of acetylcholine, 10 microgram/kg i.v., were examined in nine conscious dogs on measurements of left ventricular pressure, dP/dt, aortic pressure, heart rate, coronary blood flow, left circumflex external coronary arterial diameter, arterial and coronary sinus O2 content and calculations of late diastolic coronary resistance and left circumflex internal coronary cross-sectional area. In conscious dogs in the absence of autonomic blockade, acetylcholine induced a rapid, transient response characterized by hypotension and peak increases in coronary blood flow (+135 +/- 14%) and coronary sinus O2 content (+5.0 +/- 0.5 volume percent) and decreases in late diastolic coronary resistance (-65 +/- 3%). The peak large coronary arterial effects were observed 60 sec later at a time when arterial pressure, left ventricular end-diastolic pressure, left ventricular dP/dt and heart rate were not significantly different from control. At this time, large coronary cross-sectional area was increased ...
Background Assessment of coronary endothelial function with intracoronary acetylcholine (IC-Ach) provides diagnostic and prognostic data in patients with suspected coronary microvascular dysfunction (CMD), but is often not feasible due in part to the time and expertise needed for pharmacologic mixing. Cold pressor testing (CPT) is a simple and safe stimulus useful for either invasive or non-invasive endothelial function testing and myocardial perfusion imaging but has not been specifically evaluated among symptomatic women with signs of ischemic heart disease (IHD) who have no obstructive coronary artery disease (CAD). Methods 163 women with signs and symptoms of IHD and no obstructive CAD from the NHLBIWomens Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction (WISE-CVD) study underwent coronary reactivity testing with a Doppler flow wire (FloWire® Volcano, San Diego, CA) in the proximal left anterior descending artery. Coronary artery diameter and coronary blood flow (CBF) assessed by ...
Cardiovascular disease (CVD), particularly coronary vascular disease, is a primary contributor to diabetes-related morbidity and mortality worldwide. Specifically, dysfunction of coronary microcirculation is common in this patient population, often occurring in the absence of or preceding epicardial coronary atherosclerosis, thereby leading to impaired coronary blood flow (CBF) regulation and increased risk of myocardial ischemia/infarct. Clinically, coronary microvascular function can be assessed by determination of coronary flow reserve (CFR) (ratio of maximal hyperemic to basal CBF), and impaired CFR is a powerful independent correlate of cardiac mortality in diabetic patients (1). Importantly, recent evidence revealed that diabetic patients with preserved CFR (above the median) have cardiac event rates similar to nondiabetic patients (1). Thus, treatment strategies designed to restore CFR (i.e., coronary microvascular function) hold promise to reduce acute and long-term cardiac mortality in ...
57. Vaginal entry was possible both times and both sides have to report it unless specifically asked. It is also rather vague and certainly in the pvn was also shown to induce formation of cyclic adenosine monophosphate (camp) and leads to the further growth of the smooth muscle function in rhesus monkeys and pigs but have no prior history of sexual activity in healthy subjects associated with low total testosterone activity, that is, perhaps, the outcome was mixed. Part ii pathophysiology of erectile dysfunction in primary cases, the deaths occurred during sleep. 345. Endocrinology: The branch of the internal pudendal artery arises from the beginning. Because dsm-iv-tr classified dyspareunia not resulting188 from a relaxing effect on regional myocardial blood flow and circumferential expansion (erections). An autosomal domi- nant trait with variable success by dr. They were to explore them fully in therapy before any discussion of the patients underlying ambivalence about his sexual partner by ...
Example of antegrade coronary artery flow in the distal segment of Cx. The distal segment of the circumflex coronary artery (dCx) imaged by colour Doppler mappi
Methods and Results 54 patients with stable coronary disease undergoing PCI were divided into two groups according to the presence/absence of MS (mean age (years), MS (n = 20): 61 ± 11; no MS (n = 34): 66 ± 8, p = 0.10). All patients were on statins with optimal low-density lipoprotein (LDL) cholesterol levels (mean levels (mmol/l), MS: 2.0 ± 1.0; no MS: 2.1 ± 0.6, p = 0.79). An intracoronary thermodilution technique was used to assess endothelium-dependent (% change flow in response to intracoronary infusion of substance P (20 pmol/min)) and endothelium-independent (derived from coronary flow reserve (CFR) in response to systemic infusion of adenosine (140 μg/kg per minute)) CMF. Levels of C-reactive protein (CRP) and adipocytokines (leptin, adiponectin, resistin) were also examined. Patients with MS had impaired endothelium-dependent CMF (mean% change flow, MS: 15 ± 14; no MS: 32 ± 19, p,0.001). There was no difference in endothelium-independent CMF (CFR, MS: 3.0 ± 1.2; no MS: 3.4 ± ...
In vivo microscopic observations pharmacodynamics Aveeno active naturals protect + hydrate spf 45 cd product monograph page 21 of 30 experiments in both open and closed chest dog models may indicate that avobenzone increases coronary blood flow and simultaneously reduces coronary vascular resistance. Act avobenzone comes in release the form of an oval and shaped white tablet which contains avobenzone as subscribed
Considering that diseases of the coronary circulation are the commonest cause of premature death, it is surprising that so few books have appeared on the subject. A classic was written in 1950 by Dr. Donald Gregg, who has given Dr. Marcus permission to use the same title; one may consider this book a successor to Dr. Greggs pioneer efforts.. Marcus is the sole author (as was Gregg). He has approached the subject in a traditional way, starting with chapters on the anatomy of the coronary circulation, physiology, pathophysiology, unique characteristics of distribution of blood flow between the right and left ...
TY - JOUR. T1 - Assessment of coronary arterial flow and flow reserve in humans with magnetic resonance imaging. AU - Hundley, W. Gregory. AU - Lange, Richard A.. AU - Clarke, Geoffrey D.. AU - Meshack, Benjamin M.. AU - Payne, Jerry. AU - Landau, Charles. AU - McColl, Roderick W. AU - Sayad, Dany E.. AU - Willett, Duwayne L. AU - Willard, John E.. AU - Hillis, L. David. AU - Peshock, Ronald M. PY - 1996/4/15. Y1 - 1996/4/15. N2 - Background: The noninvasive measurement of absolute epicardial coronary arterial flow and flow reserve would be useful in the evaluation of patients with coronary circulatory disorders. Phase-contrast magnetic resonance imaging (PC-MRI) has been used to measure coronary arterial flow in animals, but its accuracy in humans is unknown. Methods and Results: Twelve subjects (7 men, 5 women; age, 44 to 67 years) underwent PC-MRI measurements of flow in the left anterior descending coronary artery or one of its diagonal branches at rest and after administration of adenosine ...
The heart failure (HF) epidemic continues to rise with coronary artery disease (CAD) as one of its main causes. Novel concepts for risk stratification to guide the referring cardiologist towards revascularization procedures are of significant value. Myocardial perfusion imaging (MPI) using single-photon emission computed tomography (SPECT) agents has demonstrated high accuracy for the detection of clinically relevant stenoses. With positron emission tomography (PET) becoming more widely available, mainly due to its diagnostic performance in oncology, perfusion imaging with that modality is more practical than in the past and overcomes existing limitations of SPECT MPI. Advantages of PET include more reliable quantification of absolute myocardial blood flow, the routine use of computed tomography for attenuation correction, a higher spatiotemporal resolution and a higher count sensitivity. Current PET radiotracers such as rubidium-82 (half-life, 76 sec), oxygen-15 water (2 min) or nitrogen-13 ...
The relative contribution of the basal, mid-cavity, and apical segments are 35% (6/17), 35% (6/17), and 30% (5/17), respectively.. Coronary Artery Territories. The AHA guidelines emphasize that there is a tremendous variability in the coronary artery blood supply to myocardial segments. The greatest variability occurs at the apical cap, which can be supplied by any of the three arteries. With the recognition of the anatomic variability the individual segments may be assigned to specific coronary artery territories as follows.. ...
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TY - JOUR. T1 - ACLS drugs used during resuscitation. AU - Rau, J. L.. AU - Sanders, A. B.. AU - Pepe, P. E.. AU - Barnes, T. A.. AU - Halperin, H. R.. AU - Kaye, PY - 1995. Y1 - 1995. N2 - In this review, I have focused on the relatively small number of drugs used in cardiac arrest, and, specifically, in ventricular tachycardia, ventricular fibrillation, and asystole. These agents range from older drugs, such as epinephrine and atropine, to the more recent agent, adenosine. Emphasis has been given to the pharmacology, and data concerning the use of these agents in cardiac arrest. Questions concerning their use have been raised, and where available, data have been reviewed suggesting courses of action for these questions. Epinephrine remains an established drug for pharmacologic control in VF and asystole, despite new questions and new agents. Although pure α agonists have shown evidence of giving better subendocardial blood flow than epinephrine, questions requiring further study remain with ...
The dynamic nature of cardiac ischemia is reflected in the concept of coronary flow reserve (CFR), first proposed by Gould in 1974. CFR is a measure of the degree to which the coronary circulation is able to increase myocardial blood flow when the perfusion bed is maximally dilated. Normal values of CFR vary by age and sex but are typically in the range of 3-4; CFR values less than 2 are generally pathologic and associated with ischemia/infarction. Contrast-enhanced MRI performed at rest and under pharmacologic stress does not measure CFR directly, but a closely related quantity, myocardial flow reserve (MFR). Like CFR, MFR has been shown to be an important predictor for future coronary events in patients with coronary artery disease and outcomes after revascularization or stenting ...
TY - JOUR. T1 - Proarrhythmic activity of intracoronary endothelin in dogs. T2 - Relation to the site of administration and to changes in regional flow. AU - Salvati, P.. AU - Chierchia, S.. AU - Dho, L.. AU - Ferrario, R. G.. AU - Parenti, P.. AU - Vicedomini, G.. AU - Patrono, C.. PY - 1991. Y1 - 1991. N2 - The endothelium-derived peptid, endothelin, has been shown to exert powerful constrictor activity in both isolated and in situ coronary arteries. Recent in vitro data on isolated cardiac myocytes suggest that the substance might also possess electrophysiologic properties. We investigated the possibility that endothelin (ET-1) may exert proarrhythmic effects when infused selectively in the coronary circulation of open-chest-anesthetized dogs. Animals were instrumented for the measurement of left anterior descending (LAD) or left circumflex (LCX) coronary artery blood flow, left systolic ventricular pressure (LSVP), dPldtmax, mean arterial pressure (MAP), and epicardial electrocardiogram ...
Although MP has a strong evidence base, its widespread application has been limited by technical complexity in its application and some subjectivity in its interpretation. MP is exquisitely sensitive for mild CAD, but problems with artifacts limit its interpretation in the absence of WM assessment; nonetheless, in our study, the number of segments with reversible MPD (in patients with abnormal MP) was 2.6 ± 1.5, and in this abnormal MP subgroup, only 28 patients had ,2 segments with reversible MPD. This emphasizes the robustness of study findings. Moreover, although mid-apical segments for each coronary territory are usually interpretable, several perfusion assessments are incomplete because of limited feasibility in the basal myocardial segments.. Although exercise testing might be considered the best protocol in which to compare WM with other parameters, as it offers maximal stress and assessment of functional capacity, we selected pharmacological stress on the basis of the inability of many ...
This article is the second in a series which presents a computer model of the left coronary arteries. The first article discussed the geometry, the governing equations, and the numerical method employed. This paper details an acute canine experiment used to validate the approach as well as the systematic investigation of several important parameters governing the left coronary circulation. These parameters include peripheral resistance, wall properties, and altered geometric properties through various stenosis/bypass configurations. With appropriate selection of parameters, the model reproduces an in vivo waveform very closely. The model also predicts many clinical phenomena, such as the "critical" value of stenosis, the dramatic reduction in flow through a stenosis when bypassed, and the restorative effect of the bypass upon flow to the distal bed. The model also is used to show that the autonomic state of the animal profoundly affects the influence of various factors, e.g., the critical value ...
In humans, basal myocardial blood flow remains constant regardless of the severity of coronary-artery stenosis. However, during hyperemia, flow progressively decreases when the degree of stenosis is about 40 percent or more and does not differ significantly from basal flow when stenosis is 80 percen …
Hello, I need help with coding doppler flow wire in the femoral artery. I have been looking and just cannot find a code for this. I apprec
Eddy currents produced the sinuses of Valsalva (out-pouchings of the aortic wall) prevent the valves occluding the os of the LM and RCA during systole, so they remain patent throughout the cardiac cycle ...
Question - Will CT Angio help in finding out the percentage of blockage in the heart ?. Ask a Doctor about Coronary circulation, Ask a Cardiologist
Dr. Wright responded: Plaque rupture. Most are progressive narrowing to the point of serious impairment of coronary blood flow with exercize etc. Causing |a href="/topics/angina" track_data="{
While vasodilators and vasoconstrictors have been studied for decades as individual components of coronary blood flow modulation, recent work by Dirk Duncker and colleagues takes a rarely-seen integrative physiological approach to elucidate the mechan
Abnormally rapid repolarisation of the infarcted muscle (accelerated opening of K+ channels). Current flow out of infarct (normal region negative relative to infarct). Occurs within seconds of infarction and last a few minutes ...
Objective To visualize epicardial and intramyocardial coronary blood flow by using a noninvasive echocardiography system.. Methods In five juvenile swines, coronary flow imaging was used to visualize the different segments of epicardial coronary and intramyocardial arteries. Pulsed-Doppler spectrums were recorded and analyzed. The left anterior descending artery (LAD) and intramyocardial coronary blood flow signals were recorded at baseline and during dipyridamole administration.. Results Epicardial and intramyocardial coronary arteries could be visualized by coronary flow imaging. The systolic component of coronary flow in the right coronary artery (RCA) was greater than in the LAD. The intramyocardial blood flow was characterized by persistent retrograde blood flow velocity during systole. Vasodilation with dipyridamole produced exaggerated differences in the phasic pattern of coronary blood flow in epicardial and intramyocardial vessels.. Conclusion Color Doppler coronary flow imaging ...
Collateral growth and coronary angiogenesis are chronic adaptations to myocardial ischemia. Collateralization helps to restore blood flow and as a result salvages myocardium in severely ischemic myocardial regions. Thus, good collateral development in patients with severe coronary artery disease (CAD) improves ventricular function and prognosis (1-3).. However, coronary collateral development is different among patients even with similar degrees of coronary artery stenosis. Several factors, such as diabetes mellitus (4) and duration of myocardial ischemic symptoms (5) have been reported to effect coronary collateral development. At the cellular level, inflammatory cells, especially monocytes have an important role in collateralization. In a series of experimental studies with animals, it has been shown that monocytes are important elements for development of collateral vessels (6-7). In a recent study, it has been demonstrated that increased circulating monocyte count is related to good ...
Dobutamine-induced wall otion abnormalities: correlations with myocardial fractional flow reserve and quantitative coronary angiography ...
Looking for online definition of post-stenotic dilation in the Medical Dictionary? post-stenotic dilation explanation free. What is post-stenotic dilation? Meaning of post-stenotic dilation medical term. What does post-stenotic dilation mean?
Recent studies have shown a good relation between myocardial perfusion scintigraphy and intracoronary Doppler flow velocity parameters.8-11 15 However, the results are not uniform regarding both the best cut off values for the distal coronary flow reserve as well as the agreement between the invasive intracoronary diagnostic technique and non-invasive myocardial perfusion scintigraphy. Miller and colleagues found an overall agreement of 89% between pharmacologic (adenosine and dipyridamole) induced stress99mTc MIBI SPECT and dCFVR (cut off value 2.0) in a cohort of patients with single and multivessel disease.8 The agreement decreased to 83% when the data are restricted to patients with single vessel disease and intermediate lesions (n = 13, 30-70% diameter stenosis). Joye and colleagues found an agreement of 94% between 201thallium and dCFVR (cut off value 2.0) in 30 patients with intermediate lesions (40-70% diameter stenosis) in the presence of single and multivessel disease.9 ...
AbstractBackground:Well-developed coronary collateral circulation usually results in fewer infarct size, improved cardiac function, and fewer mortality. Traditional coronary risk factors (diabetes, hypertension, and smoking) have some effects on coronary collateral circulation. However, the associat
A total of 405 men and 813 women were included in the present study. Women were slightly older, and more likely to be Hispanic and nonwhite than men. Compared to men, women were also more frequently obese and hypertensive. However, women were less likely to use tobacco. Chest pain and dyspnea were also more frequent in women than men. The pretest clinical risk based on the gender-neutral modified Duke clinical risk score was higher among women than men (35% vs. 29%, respectively, p = 0.007). Left ventricular ejection fractions were slightly higher among women, although they were normal in both genders. Coronary microvascular dysfunction was highly prevalent both in men and women (51% and 54%, respectively; P [Fisher exact test] = 0.39; P [equivalence] = 0.0002). Regardless of gender, coronary flow reserve was a powerful incremental predictor of MACE (hazard ratio, 0.80 [95% confidence interval, 0.75-086] per 10% increase in coronary flow reserve; p < 0.0001), and resulted in favorable net ...
We have developed a multi-modal imaging approach for SIRT, combining 99mTc-MAA SPECT/CT and/or 90Y PET, 18F-FDG PET/CT, and contrast-enhanced CBCT for voxel-based dosimetry, as a tool for treatment planning and verification. For radiation dose prediction calculations, a segmentation of the total liver volume and of the liver perfusion territories is required. In this paper, we proposed a procedure for multi-modal image analysis to assist SIRT treatment planning. The pre-treatment 18F-FDG PET/CT, 99mTc-MAA SPECT/CT, and contrast-enhanced CBCT images were registered to a common space using an initial rigid, followed by a deformable registration. The registration was scored by an expert using Likert scores. The total liver was segmented semi-automatically based on the PET/CT and SPECT/CT images, and the liver perfusion territories were determined based on the CBCT images. The segmentations of the liver and liver lobes were compared to the manual segmentations by an expert on a CT image. Our methodology
Serotonin constricts coronary arteries with endothelial dysfunction, a common abnormality in cardiac transplant recipients. To assess whether endothelial dysfunction is associated with myocardial blood flow (MBF) abnormalities, 24 patients were studied 1 to 12 months after transplantation. Serotonin in increasing doses (1, 10, and 20 micrograms/min for 2.5 min each) was infused into the coronary circulation. Diameters were measured by quantitative angiography. Fourteen patients (group A) had a pronounced artery constriction (diameter reduction | 40%), while in 10 other patients (group B), such a constriction was never reached. No patient had evidence of rejection and all had angiographically normal coronary arteries. MBF was measured at rest and after intravenous dipyridamole with dynamic nitrogen-13 ammonia positron emission tomography (PET). The resting MBF was higher in group A than in group B (94 +/- 12 vs 74 +/- 15 ml/min/100 g of tissue; p | 0.05). During dipyridamole, MBF was not significantly
New life-saving treatments for Coronary artery disease in clinical trial on Assessment of Global Myocardial Perfusion Reserve Using Coronary Sinus Flow Measurements
Recently, coronary microvascular function was documented to be impaired even in patients with prehypertension. However, the impact of antihypertensive level on improvement of coronary microvascular dysfunction in hypertensive patients remains to be established. We investigated the optimal blood pres
AIMS: Primary percutaneous coronary intervention (PPCI) is the optimal treatment for patients presenting with ST-elevation myocardial infarction (STEMI). An elevated index of microcirculatory resistance (IMR) reflects microvascular function and when measured after PPCI, it can predict an adverse clinical outcome. We measured coronary microvascular function in STEMI patients and compared sequential changes before and after stent implantation. METHODS AND RESULTS: In 85 STEMI patients, fractional flow reserve, coronary flow reserve, and IMR were measured using a pressure wire (Certus, St Jude Medical, St Paul, MN, USA) immediately before and after stent implantation. Stenting significantly improved all of the measured parameters of coronary physiology including IMR from 67.7 [interquartile range (IQR): 56.2-95.8] to 36.7 (IQR: 22.7-59.5), P | 0.001. However, after stenting, IMR remained elevated (|40) in 28 (32.9%) patients. In 15 of these patients (17.6% of the cohort), only a partial reduction in IMR
Coronary perfusion pressure (CPP) refers to the pressure gradient that drives coronary blood pressure, meaning the difference between the diastolic aortic pressure and the right atrial end diastolic pressure. It is a term used mainly in research concerning cardiac arrest. In this context, it is assumed that the minimum CPP needed for a successful outcome is 15mm Hg. CPP is a part of normal blood pressure that is specifically responsible for coronary blood flow. CPP is also, generally, a surrogate term for coronary blood flow. During cardiac arrest, CPP is one of the most important variables associated with the likelihood of return of spontaneous circulation (ROSC), the restoration of a pulse. A CPP of at least 15 mmHg is thought to be necessary for ROSC. Coronary perfusion pressure can also be known simply as Perfusion Pressure. Sutton; et al. (August 2014). "Hemodynamic-directed cardiopulmonary resuscitation during in-hospital cardiac arrest". Resuscitation. 85 (8): 983-986. ...
Definition of Circumflex coronary artery in the Legal Dictionary - by Free online English dictionary and encyclopedia. What is Circumflex coronary artery? Meaning of Circumflex coronary artery as a legal term. What does Circumflex coronary artery mean in law?
Because structural changes of coronary microcirculation (medial hypertrophy, fibromuscular hyperplasia, intimal proliferation, and perivascular fibrosis) have been shown in diabetic patients (89101112) and may be responsible for the reduction of maximal coronary blood flow and coronary reserve (1,3), the uncoupling between coronary microvascular adaptation and myocardial oxygen demand during sympathetic stimulation by the CPT might be explained by the inability of microvessels to dilate. Because papaverine was able to induce an important increase in coronary blood flow, it is unlikely that structural changes of the coronary microvasculature could have been the cause of the weak increase of coronary blood flow in diabetic patients during CPT.. It has been well established that diabetes and hyperglycemia impair peripheral and epicardial coronary artery endothelial function (1,2,19,3031323334353637). The responses of epicardial coronary arteries to the CPT were abnormal in our diabetic patients, ...
One of the major limitations of reperfusion therapy in acute myocardial infarction (AMI) is the presentation of no-reflow phenomenon. In 25 to 30% of patients with AMI, myocardial blood flow is occasionally profoundly reduced, even after coronary recanalisation, because of microvascular dysfunction - so-called no-reflow phenomenon. Patients with this phenomenon are regarded as a high risk group among patients with reperfused AMI. Clinical studies using myocardial contrast echocardiography have demonstrated that intracoronary injection of calcium antagonists or potassium channel agonists in conjunction with coronary reperfusion can augment myocardial blood flow and that this was associated with better functional and clinical outcomes than with percutaneous transluminal coronary angioplasty alone. Thus, it is possible to prevent reperfusion injury and improve cardiac function using a adjunctive pharmacological intervention, either intravenously or by infusion directly into the coronary artery ...
TY - JOUR. T1 - FAILURE OF THE NITROUS OXIDE TISSUE EQUILIBRATION METHOD FOR THE DETERMINATION OF BRAIN AND MYOCARDIAL BLOOD FLOW UNDER CONTROLLED CONDITIONS. AU - Reid, Michael A.. AU - Runciman, William B.. AU - McLean, Colin F.. AU - Mather, Laurence E.. PY - 1992. Y1 - 1992. N2 - 1. Two adult merino ewes were prepared with intravascular cannule for sampling aortic root blood, sagittal sinus blood and coronary sinus blood. 2. One week after preparation the animals were anaesthetized then ventilated with a gas mixture containing 10% nitrous oxide (N2O) for 60 min. Serial measurements of brain and myocardial blood flow were made using the N2O tissue equilibration method of Kety and Schmidt. 3. N2O failed to achieve matching arteriovenous blood concentration equality and saturation of the relevant tissues. Valid use of the Kety‐Schmidt method, therefore, could not be confirmed. 4. Because of the failure of the arteriovenous equilibration, serially determined brain and myocardial blood flows ...
As coronary artery disease may also occur during childhood in some specific conditions, we sought to assess the feasibility and accuracy of perfusion cardiovascular magnetic resonance (CMR) in paediatric patients. First-pass perfusion CMR studies were performed under pharmacological stress with adenosine and by using a hybrid echo-planar pulse sequence with slice-selective saturation recovery preparation. Fifty-six perfusion CMR examinations were performed in 47 patients. The median age was 12 years (1 month-18 years), and weight 42.8 kg (2.6-82 kg). General anaesthesia was required in 18 patients. Mean examination time was 67 ± 19 min. Diagnostic image quality was obtained in 54/56 examinations. In 23 cases the acquisition parameters were adapted to patients size. Perfusion CMR was abnormal in 16 examinations. The perfusion defects affected the territory of the left anterior descending coronary artery in 11, of the right coronary artery in 3, and of the circumflex coronary artery in 2 cases. Compared
1. The electrical stimulation model of thrombus formation was tested on rabbit carotid artery and Actapted to sheep left circumflex coronary artery (LCCA). 2. LCCA blood flow, mean arterial pressure (MAP), heart rate (HR) and ECG were monitored continuously and arterial and coronary venous blood samples were taken for radioimmunoassay of thromboxane B2. 3. Stimulation of the LCCA mimicked acute myocardial infarction; reduction in LCCA blood flow preceded a fall in MAP and appearance of ECG abnormalities. 4. Thromboxane B2 levels rose by 126% 35min after stimulation. 5. These findings support the proposal by other authors that thromboxane plays an important role in the pathogenesis of acute myocardial infarction ...
Coronary collateral circulation plays an important role to protect myocardium from ischemia, preserve myocardial contractility and reduce cardiovascular events. Chronic kidney disease (CKD) is associated with poor coronary collateral development and
IN 1947, Eckenhoff et al. demonstrated that myocardial oxygen supply matches myocardial oxygen demand in steady-state. [1] This finding was confirmed by a number of investigators, using different species of experimental animals. [2-4] The dynamic behavior of the coronary arterial system was first described by Belloni and Sparks in 1977. [5] Using open-chest dogs, they calculated the time course of changes in coronary vascular resistance (CVR) in response to pacing-induced changes in heart rate (HR). Using dogs and goats, Dankelman et al. showed that the rate of change of CVR can be quantified by a t50value, calculated from the ratio of beat-averaged coronary perfusion pressure and coronary blood flow. This t50value varies in different species and can be influenced by drugs. [6-8] Neither in experimental animals nor in humans is it known whether there is a difference in the rate of coronary flow regulation during awake and anesthetized conditions, although the impact of anesthesia on the static ...
The heart failure (HF) epidemic continues to rise with coronary artery disease (CAD) as one of its main causes. Novel concepts for risk stratification to guide the referring cardiologist towards revascularization procedures are of significant value. Myocardial perfusion imaging (MPI) using single-photon emission computed tomography (SPECT) agents has demonstrated high accuracy for the detection of clinically relevant stenoses. With positron emission tomography (PET) becoming more widely available, mainly due to its diagnostic performance in oncology, perfusion imaging with that modality is more practical than in the past and overcomes existing limitations of SPECT MPI. Advantages of PET include more reliable quantification of absolute myocardial blood flow, the routine use of computed tomography for attenuation correction, a higher spatiotemporal resolution and a higher count sensitivity. Current PET radiotracers such as rubidium-82 (half-life, 76 sec), oxygen-15 water (2 min) or nitrogen-13 ammonia (10
Adenosine cardiovascular magnetic resonance (CMR) can accurately quantify myocardial perfusion reserve. While regadenoson is increasingly employed due to ease of use, imaging protocols have not been standardized. We sought to determine the optimal regadenoson CMR protocol for quantifying myocardial perfusion reserve index (MPRi) - more specifically, whether regadenoson stress imaging should be performed before or after rest imaging. Twenty healthy subjects underwent CMR perfusion imaging during resting conditions, during regadenoson-induced hyperemia (0.4 mg), and after 15 min of recovery. In 10/20 subjects, recovery was facilitated with aminophylline (125 mg). Myocardial time-intensity curves were used to obtain left ventricular cavity-normalized myocardial up-slopes. MPRi was calculated in two different ways: as the up-slope ratio of stress to rest (MPRi-rest), and the up-slope ratio of stress to recovery (MPRi-recov). In all 20 subjects, MPRi-rest was 1.78 ± 0.60. Recovery up-slope did not return to
In an attempt to improve myocardial performance in acute myocardial infarction with shock, increments of coronary perfusion pressure were achieved by partial obstruction of the abdominal aorta with a balloon catheter introduced via a femoral artery in 28 dogs with plastic sphere coronary embolization. Alterations of central aortic pressure, coronary sinus flow, cardiac output, left atrial pressure, left ventricular work, left ventricular oxygen consumption, coronary vascular resistance, left ventricular mechanical efficiency, and left ventricular lactate and pyruvate extraction were determined before and after coronary embolization and at intervals during 1 hour of abdominal aortic obstruction. After coronary embolization, aortic pressure, ...
The answer is B. (Hursts The Heart, 14th Edition, Chap. 34) Experimentally and clinically, maximal hyperemic flow for determining CFR is achieved pharmacologically by arteriolar vasodilating drugs such dipyridamole, adenosine, and regadenoson. Progressive coronary narrowing reduces CFR with little change in resting flow until an approximately 80% to 90% diameter stenosis. At these levels of severe stenosis, resting blood flow falls (option A), but some residual CFR capacity remains upon pharmacologic vasodilator stimulus. Stenosis severe enough to reduce resting perfusion does not elicit all remaining reserve vasodilator capacity because of a self-regulating mechanism that protects subendocardial perfusion. At such severe stenosis reducing resting perfusion, any increase in vasodilator-mediated increased ...
TY - JOUR. T1 - Role of potassium channels in coronary vasodilation. AU - Dick, Gregory M.. AU - Tune, Johnathan D.. PY - 2010/1/1. Y1 - 2010/1/1. N2 - K+ channels in coronary arterial smooth muscle cells (CASMC) determine the resting membrane potential (Em) and serve as targets of endogenous and therapeutic vasodilators. Em in CASMC is in the voltage range for activation of L-type Ca2+ channels; therefore, when K+ channel activity changes, Ca2+ influx and arterial tone change. This is why both Ca2+ channel blockers and K+ channel openers have such profound effects on coronary blood flow; the former directly inhibits Ca2+ influx through L-type Ca2+ channels, while the latter indirectly inhibits Ca2+influx by hyperpolarizing Em and reducing Ca2+ channel activity. K+ channels in CASMC play important roles in vasodilation to endothelial, ischemic and metabolic stimuli. The purpose of this article is to review the types of K+ channels expressed in CASMC, discuss the regulation of their activity by ...
Coronary blood flow closely matches to metabolic demands of heart and myocardial oxygen consumption and is conditioned by function of coronary resistance vessels. The microvascular endothelium of coronary resistance vessels is exposed to a spatially
RESULTS: A total 269 patients were participated in the study population (55 in CIN(+) group, 214 in CIN(-) group). The blood creatinine levels were significantly higher in the CIN(+) group on the 48-72 hours following the coronary angiography. In the studied population, 70 out of 269 patients had a good CCC according the Rentrop classification (64 patients [30%] in the CIN(-) group, six patients [16%] in the CIN(+) group). The frequency of the well-developed coronary collaterals were significantly higher in the CIN(-) group ( ...
Left ventricular hemodynamics, dimensions and coronary sinus blood flows were measured simultaneously after infusions of dobutamine and dopamine. Ten patients were studied 6, 10 to 15, and 24 hr after cardiopulmonary bypass surgery. The dose of each drug was adjusted to increase cardiac output by 25%. Heart rate was held constant with atrial pacing. Dobutamine and dopamine increased peak left ventricular dP/dt from baseline values by 72% vs 58% during the early study, 77% vs 78% in the intermediate study, and 95% vs 79% in the late study (all NS, difference between drugs). Similarly, there were no significant differences in hemodynamic response or in cardiac dimensions after the two drugs in any period. Both drugs increased myocardial oxygen uptake during the intermediate and late studies (32% vs 33% and 34% vs 25%). With dobutamine this increase was matched by a similar increase in coronary blood flow; however, failure of the expected increase in coronary blood flow with dopamine suggested ...
To evaluate the source of ST depression, a sheep model of subendocardial ischaemia using partial coronary artery ligation coupled with atrial pacing was developed. Ischaemia was induced initially in either the left anterior descending coronary artery or the left circumflex coronary artery territory and subsequently in the territory of the other vessel. The ischaemic regions were documented by a fluorescent microsphere technique. During ischaemia potentials were mapped simultaneously from the endocardium and the epicardium. The distributions of epicardial potentials from either ischaemic source were very similar (0.77±0.14, P,0.0001), both showing ST depression on the free wall of the left ventricle, and no association between the ST depression and the ischaemic region. At the same time, the endocardial ST elevation was directly associated with the region of reduced blood flow. Insulating the heart from the surrounding tissue with plastic increased the magnitude of epicardial and endocardial ST ...
The effects of Morinda citrifolia (Rubiceace) extract on coronary perfusion pressure, contractility and heart rate of isolated rats hearts were studied by using the technique of Langendorff system. Sodium nitroprusside (SNP) was used as a positive control and standard while saline was used as negative control. The extract at doses of 1.0 and 10 mg, respectively showed a significant decrease in coronary perfusion pressure compared with saline. The extract dose of 10 mg showed a maximum decrease in coronary perfusion pressure, developed tension and heart rate. The next part of the study was to investigate the involvement of nitric oxide in the coronary vasodilatory effects of the extract. The inhibitor of nitric oxide synthesis, NG-nitro-L-arginine metil ester (L-NAME) 300 μM was perfused together with Krebs-Henseleit solution in the heart for test group, while the time-matched control group without L-NAME. L-NAME did not abolish the decrease of coronary perfusion pressure and developed tension ...
The purpose of this thesis has been to validate the in-vitro heart simulation model of the coronary arteries called Flowlab, identify limitations and potential problems, and to offer suggestions for improvement. Flowlab emulates arterial characteristics such as pressure and flow, providing a simulation environment with the ability to measure the volumetric coronary blood flow and arterial blood pressure. Compared to current simulation systems, this will give a better understanding of both position and severity of the cardiovascular disease, and also provide essential information regarding the hemodynamics in the coronary arteries.. To understand the fluid dynamics of the coronary system and gain a deeper understanding of the arterial function and physiology, the first phase of this thesis will focus on gathering information regarding the anatomy, physiology and hemodynamics of the coronary arteries. This will also be done to provide the Flowlab construction with appropriate measurements for the ...
The human coronary circulation is not an end-arterial system. Coronary collateral circulation has been shown to have a significant protective
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OBJECTIVES. The aim of this study was to evaluate myocardial blood flow regulation in collateral-dependent myocardium of patients with coronary artery disease. BACKGROUND. Despite great clinical relevance, perfusion correlates of collateral circulation in humans have rarely been estimated by quantitative methods at rest and during stress. METHODS. Nineteen patients with angina and isolated occlusion of the left anterior descending (n = 14) or left circumflex (n = 5) coronary artery were evaluated. Using positron emission tomography and nitrogen-13 ammonia, we obtained flow measurements at baseline, during atrial pacing-induced tachycardia and after intravenous administration of dipyridamole (0.56 mg/kg body weight over 4 min). Flow values in collateral-dependent and remote areas were compared with values in 13 normal subjects. RESULTS. Flow at rest was similar in collateralized and remote myocardium (0.61 +/- 0.11 vs. 0.63 +/- 0.17 ml/min per g, mean +/- 1 SD), and both values were lower than ...
Coronary heart disease (CHD) is a major health concern for Americans and people worldwide. Arteriogenesis, an adaptive remodeling process in which pre-existing collateral arterioles remodel to form large diameter conductance arteries, has received recent attention for its therapeutic potential in treating CHD, but the mechanisms regulating the process remain incompletely understood. In particular, little is known about how collateral flow, and the resulting effect of shear stress acting along the collateral vessel wall, regulates coronary collateralization. This Thesis combines a series of experimental systems to define the responses evoked in endothelial cells exposed to hemodynamic waveforms characteristic of coronary collateral vessels and the subsequent paracrine effects on smooth muscle cells. Initially, a lumped parameter model of the human coronary collateral circulation was used to simulate normal (NCC) and adaptive remodeling (ACC) coronary collateral shear stress waveforms. These ...
Obesity is associated with impaired coronary collateral vessel development. Yilmaz, M.B.; Biyikoglu, S.F.; Akin, Y.; Guray, U.; Kisacik, H.L.; Korkmaz, S. // International Journal of Obesity & Related Metabolic Disorders;Dec2003, Vol. 27 Issue 12, p1541 BACKGROUND:: Chronic myocardial ischaemia due to coronary artery stenosis or occlusion has been shown to increase the growth of coronary collateral circulation. Collateralization leads to increased oxygen delivery to the area at risk and hence may reduce ischaemia, prevent infarction and... ...
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LEMOS DE OLIVEIRA, LUCIANO FONSECA... Regional Myocardial Perfusion Disturbance in Experimental Chronic Chagas Cardiomyopathy. JOURNAL OF NUCLEAR MEDICINE 59 n.9 p. 1430-1436 SEP 1 2018. Journal article.
TY - JOUR. T1 - Comparative 13C and 31P NMR assessment of altered metabolism during graded reductions in coronary flow in intact rat hearts. AU - Weiss, R. G.. AU - Chacko, V. P.. AU - Glickson, J. D.. AU - Gerstenblith, G.. PY - 1989/1/1. Y1 - 1989/1/1. N2 - 13C NMR spectroscopy may offer a unique ability to characterize the metabolic response to graded reductions in coronary flow since it allows repeated, nondestructive identification of products of intermediary metabolism in the same heart. The sensitivity of 13C parameters of glucose metabolism was compared with changes in levels of phosphocreatine, ATP, and pH as determined by 31P NMR in the intact, beating rat heart model during graded reductions in coronary flow. Experiments were performed during 60 min of perfusion wiht [1-13C]glucose (5 mM) at normal flow (15 ml/min) and at the reduced flow rates of 5 and 2 ml/min. During flow at 5 ml/min, isovolumic developed pressure fell to 51 ± 4% of control. Although phosphocreatine, ATP, and pH ...
Percent change in coronary blood flow, coronary vascular resistance and coronary epicardial diameter in response to (A) endothelium-dependent vasodilation with acetylcholine and (B) endothelium-independent vasodilation with sodium nitroprusside. (C) Percent change in coronary blood flow and coronary vascular resistance in response to adenosine. Overweight and obese subjects (BMI ≥ 25 kg/m2) in dark columns and normal weight subjects (BMI , 25kg/m2) in open columns. Results expressed as mean ± SEM. Probability values by students t-test ...
... An anterior view of the heart shows the right coronary artery and the anterior descending branch of the left coronary
The Fractional Flow Reserve (FFR) in the LAD was grossly abnormal, 0.37. The pressure-flow index of stenosis severity, the Hyperaemic Stenosis Resistance (hSR=aortic pressure - distal pressure/mean peak velocity), was also measured. hSR values in excess of 0.80 mmHg-1 cm-1 s have been shown to correlate with ischaemia on non-invasive testing.1 This was 2.91 mmHg-1 cm-1 s in the LAD, concordant with the FFR result. Microvascular resistance (hMR) was also calculated, (distal coronary pressure/mean peak velocity). hMR is thought to be independent of epicardial coronary disease and values in excess of 2.0 mmHg cm s-2 are considered abnormal, although there is significant heterogeneity even in individuals with similar clinical characteristics. In the LAD territory hMR was elevated at 2.3 mmHg cm s-2 (Fig 3a ...
The slow coronary flow phenomenon (SCF), a condition described by the presence of inappropriate delay in the progression of intracoronary contrast during angiography in the absence of stenoses, has been shown in some patients presenting with chest pa
It has recently become apparent that epicardial flow does not necessarily imply tissue level or microvascular perfusion 21,22 . This led to the recent
The presence of stenotic lesions in multiple arteries can lead to a condition called "vascular steal." This occurs when dilation of one vascular network (e.g., during exercise or vasodilator therapy) "steals" blood flow from another region within the organ that is already maximally dilated because of the presence of proximal lesions.. Coronary steal phenomenon refers to the phenomenon in which small vessel dilation and an increase in flow to an area already well-perfused myocardium leads to a decrease in flow to another area of myocardium with borderline perfusion and limited coronary reserve. Coronary steal can occur between 2 arteries connected by collateral vessels (intercoronary steal) or from subendocardium to subepicardium distal to a coronary stenosis (transmural steal).. It is seen with drugs like Dipyridamole, Hydralazine and Isoflurane.. ...
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www.MOLUNA.de Coronary Vasculature [4212655] - This book surveys coronary vasculature from its embryonic origins through postnatal growth, adulthood and senescence, with chapters on normal coronary development, anomalies, adaptations to exercise training, aging, hypoxia, myocardial ischemia and more.Ischemic heart disease is the leading cause of morbidity and mortality in the developed world. The high metabolism and
A collateralized debt obligation is an investment that is backed by a collection of several different assets. While collateralized...
This application supports visualization, diagnostic assessment, and quantification of cardiac images focusing on the left ventricular myocardium: specifically providing quantitative myocardial blood flow measurements for CT images, including the ability to identify areas of decreased perfusion within the myocardium that may represent ischemia. The application supports axial, ECG-gated CT images, consisting of multiple time shots of the same myocardial region over time. CT Dynamic Myocardial Perfusion displays the results as a composite image (single image that is calculated from a set of time course images at a single location). ...
It would be reasonable in a patient with multivessel CAD and a significant reduction in left ventricular (LV) function to presume that his/her cardiac dysfunction is directly related to myocardial ischemia resulting from a decrease in coronary blood flow and coronary flow reserve (CFR). Although all of the following are associated with LV dysfunction, whether the myocardium is stunned, hibernating, or infarcted depends on the duration, chronicity, severity, and repetitiveness of the myocardial ischemia (Figure 35-1). These different states of the myocardium can also coexist in different parts of the heart. ...
In critical aortic stenosis, cardiac output is limited and fixed. ACEI being vasodilator, dilates the arterioles, and causes hypotension and diminished blood pressure. Perfusion pressure diminution causes coronary hypoperfusion and ischaemia and chances of MI and ischaemic damage to vital organ is increased ...
The causes of coronary microvascular disease are the same as atherosclerosis Unhealthy blood cholesterol levels, unhealthy eating habits, lack of exercise, etc.