The effects on coronary blood flow of the endecapeptide Eledoisin have been studied in the anesthetized dog. Eledoisin increases coronary blood flow without increasing myocardial contractility and heart rate. Nitroglycerin and the polypeptide bradykinin increase coronary blood flow in the same way, but are markedly less active than Eledoisin. l-Epinephrine increases coronary blood flow, but at the same time produces a stimulating action on the myocardium.. ...

Cardiac transplantation is frequently associated with accelerated coronary atherosclerosis and immune-mediated microvascular injury. To determine if orthotopic cardiac transplantation impairs the capacity of the coronary vasculature to vasodilate and conduct hyperemic blood flow, maximal coronary vasodilator reserve was measured in 25 cardiac allograft recipients with no evidence of rejection 6-57 months after transplantation and in 20 normal subjects. Left ventricular wall thickness was assessed echocardiographically, and epicardial coronary anatomy was evaluated by quantitative coronary angiography. Coronary vasodilator reserve (CVDR) was measured in all patients with a coronary Doppler catheter and a maximally vasodilating dose of intracoronary papaverine. CVDR measured in the transplant recipients with normal coronary arteries, left ventricular function, and wall thickness (5.0 +/- 0.3 [mean +/- SEM] peak/resting velocity; range, 3.8-7.3; n = 16) was not different from that of normal ...

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 ...

TY - JOUR. T1 - Coronary microvascular dysfunction in patients with microvascular angina. T2 - Analysis by TIMI frame count. AU - Sun, Hongtao. AU - Fukumoto, Yoshihiro. AU - Ito, Akira. AU - Shimokawa, Hiroaki. AU - Sunagawa, Kenji. PY - 2005/11/1. Y1 - 2005/11/1. N2 - We have previously reported that angina pectoris persists in patients with coronary microvascular spasm (MVS) even on calcium channel blockers. Because measurement of myocardial lactate production in the coronary sinus is necessary to diagnose MVS, a more feasible diagnostic method needs to be developed. In this study, we examined the diagnostic significance of Thrombolysis in Myocardial Infarction (TIMI) frame count, a marker of coronary blood flow, in 131 consecutive patients who underwent provocation test for coronary spasm with acetylcholine (ACh). Epicardial coronary spasm (ES) was diagnosed as more than 75% of ACh-induced vasoconstriction noted by coronary angiography. MVS was diagnosed as ACh-induced myocardial ischemia ...

Since the gradient between aortic pressure and left ventricular diastolic pressure is a major determinant of coronary blood flow, a change in left ventricular relaxation by its effect on early diastole could diminish early diastolic coronary flow. Two interventions that resulted in impaired left ventricular relaxation, hypothermia, and reperfusion following a left anterior descending coronary artery occlusion were studied to evaluate whether there were associated changes in coronary blood flow. With both interventions, there was a significant prolongation of left ventricular relaxation (p less than 0.01) accompanied by a significant decrease in early diastolic coronary blood flow (p less than 0.01). Verapamil did not have a significant effect on these hemodynamic changes during hypothermia. However, verapamil significantly blunted the effects of reperfusion following ischemia on ventricular relaxation (p less than 0.002) and early diastolic coronary blood flow (p less than 0.01). Thus, impaired ...

TY - JOUR. T1 - Acute attenuation of glycocalyx barrier properties increases coronary blood volume independently of coronary flow reserve. AU - Brands, Judith. AU - Spaan, Jos A. E.. AU - Van den Berg, Bernard M.. AU - Vink, Hans. AU - VanTeeffelen, Jurgen W. G. E.. PY - 2010/2. Y1 - 2010/2. KW - adenosine. KW - blood flow. KW - coronary circulation. KW - indicator-dilution. U2 - 10.1152/ajpheart.01306.2008. DO - 10.1152/ajpheart.01306.2008. M3 - Article. C2 - 19940074. VL - 298. SP - H515-H523. JO - American Journal of Physiology-heart and Circulatory Physiology. JF - American Journal of Physiology-heart and Circulatory Physiology. SN - 0363-6135. IS - 2. ER - ...

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 ...

Some potential limitations must be considered when interpreting these data. First, pressure-derived indexes were compared with ST-segment changes during exercise ECG as a marker of myocardial ischemia. This may represent a potential limitation, since sensitivity and specificity of exercise ECG for detecting the presence of significant angiographic coronary artery narrowings were found to vary widely,29 reflecting variations in patient selection and exercise test methodology. However, despite these limitations, the provocation of ST-segment depression in response to increased cardiac work is the simplest and most widely accepted test for the documentation of myocardial ischemia in routine clinical practice.30 31 Moreover, the finding of a coronary narrowing at angiography in a patient with chest pain will most often trigger a revascularization procedure if ST-segment depressions are documented during exercise. Therefore, the comparison of transstenotic pressure gradients and of FFRmyo with the ...

TY - JOUR. T1 - Impact of obesity on coronary microvascular function in the Zucker rat. AU - Prakash, Rajan. AU - Mintz, James. AU - Stepp, David W. PY - 2006/7. Y1 - 2006/7. N2 - Objective: To test the hypothesis that vasomotor control is impaired in the coronary circulation of prediabetic obese (OZR) relative to lean Zucker rats (LZR). Methods: Cardiac function was assessed with in vivo measures of cardiac output and microvascular structure and function was assessed in vitro using videomicroscopic techniques. Results: OZR showed a marked hyperdynamic circulation with an increased cardiac output and elevated stroke volume. Contrary to the stated hypothesis, the authors found no diminution of vasodilator function and no augmentation of vasoconstriction. Indeed, dilation to acetylcholine was potentiated and vasoconstriction to endothelin was reduced in OZR compared to LZR. Structural characteristics of small coronary arteries were similar between LZR and OZR. Conclusions: Taken together, these ...

Myocardial perfusion reserve (hyperemic divided by basal myocardial blood flow) describes vasodilator responsiveness of coronaryresistive vessels. The effect of aging and gender on myocardial perfusion reserve remains controversial. Methods: We studied 56 normal volunteers (21 women, 35 men; aged 50 +/- 20 yr, range 21-86 yr) with O-15-water PET to measure myocardial blood flow during basal and hyperemic stales with intravenous dipyridamole (0.56 mg/kg, n = 46) or adenosine (140 mu g/kg/min, n = 10). For comparative analysis, patients were grouped according to age: ,30 yr (n = 11), 30-49 yr (n = 18), 50-69 yr (n = 15) and greater than or equal to 70 yr (n = 12). Results: Overall, basal flow was 1.00 +/- 0.26 ml/min/g and hyperemic flow was 3.31 +/- 1.38 ml/min/g, resulting in a myocardial perfusion reserve of 3.38 +/- 1.35. There was an increase in basal flow with age (r = 0.45, p , 0.025), although hyperemic flow was only lower in patients greater than or equal to 70 yr, causing a significant ...

PURPOSE OF REVIEW: The purpose of this review was to summarize the healing processes after myocardial infarction (MI) and to relate these temporal changes to data from serial imaging obtained by cardiac magnetic resonance, and then to relate these findings to the invasive measures of the indices of coronary physiology (e.g., fractional flow reserve, coronary flow reserve and index of microcirculatory resistance). RECENT FINDINGS: Indices of coronary physiology measured with an intracoronary wire represent an easily and readily available diagnostic tool for the management of coronary artery disease. Additionally, they give insight into the functional status of the coronary microvasculature. Recent evidence has confirmed initial observations that microvascular recovery occurs after MI and that this is reflected by a progressive improvement of all the indices of coronary physiology over time. More importantly, it has been clarified that this process is variable, but probably predictable as it is affected

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 ...

Objective: To test whether preserved coronary flow reserve (CFR) two days after reperfused acute myocardial infarction (AMI) is associated with less microvascular dysfunction ( no-reflow phenomenon) and is predictive of myocardial viability.. Design: 24 patients with anterior AMI underwent CFR assessment in the left anterior descending coronary artery (LAD) with transthoracic echocardiography and myocardial contrast echocardiography (MCE) 48 h after primary angioplasty in the LAD (mean 4 (SD 2) and 3 (1) days, respectively). Low-dose dobutamine echocardiography was performed 6 (3) days after AMI and follow-up echocardiography at three months.. Results: No-reflow extent was greater in patients with impaired CFR (, 2.5) than in those with preserved CFR (, 2.5) (55 (35)% v 11 (25)%, p , 0.001). MCE reflow was more common in patients with preserved CFR (8/12) than in those with reduced CFR (1/12, p , 0.05). Wall motion score index in the LAD territory (A-WMSI) was similar at the first ...

Oral vitamin C restores coronary microcirculatory function and impaired coronary flow velocity reserve against oxidative stress in smokers.

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

TY - JOUR. T1 - The off-pump implantation of an apicoaortic valved graft is safe and has no negative impact on coronary flow and hemodynamics. AU - Tsirikos Karapanos, Nikolaos. AU - Suddendorf, Scott H.. AU - Li, Zhuo. AU - Huebner, Marianne. AU - Park, Soon J.. AU - Joyce, Lyle D.. AU - Daly, Richard C.. PY - 2011/9/1. Y1 - 2011/9/1. N2 - OBJECTIVE:: To determine the hemodynamic effect of an off-pump apicoaortic valved graft (AAVG) implantation, we performed a quantitative coronary flow analysis in a swine model of severe aortic stenosis. METHODS:: In 10 swine, cardiac output, coronary flow, right common carotid artery flow, and internal mammary artery flow were measured along with left and right ventricular pressures and aortic and pulmonary artery pressures. A novel AAVG was implanted off-pump on the left ventricular (LV) apex using a specially designed implantation tool and anastomosed to the descending thoracic aorta. Aortic flow was measured proximally and distally of the ...

TY - JOUR. T1 - Myocardial perfusion reserve. T2 - Assessment with multisection, quantitative, first-pass MR imaging. AU - Wilke, Norbert. AU - Jerosch-Herold, Michael. AU - Wang, Ying. AU - Huang, Yimei. AU - Christensen, Betsy V.. AU - Stillman, Arthur E.. AU - Ugurbil, Kamil. AU - McDonald, Kenneth. AU - Wilson, Robert F.. PY - 1997/8. Y1 - 1997/8. N2 - PURPOSE: To demonstrate the feasibility of determining myocardial blood flow changes and the myocardial perfusion reserve with magnetic resonance (MR) first-pass imaging, to validate the MR results by means of comparison with radiolabeled microsphere flow measurements in an animal model, and to compare the coronary flow reserve with the perfusion reserve at MR imaging in patients with hemodynamically nonsignificant coronary lesions and angina. MATERIALS AND METHODS: Arrhythmia-insensitive, first-pass, multisection, T1- weighted MR imaging with contrast agent enhancement was performed in eight pigs with acute ischemia and in eight adult ...

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. ...

We assessed myocardial perfusion abnormalities during exercise with thallium scintigraphy in patients with HCM. Previous studies have shown that the prevalence of perfusion abnormalities ranges from 52 to 74% in patients with HCM (4,8,9). In the present study, the prevalence of perfusion abnormalities, including perfusion defects (fixed and reversible) and LVCD, was 69%. Thus, the present study confirms that perfusion abnormalities are common in patients with HCM. It is generally considered in patients with HCM that fixed perfusion defects may represent regional myocardial fibrosis and scarring (8,10), whereas reversible perfusion defects may represent regional myocardial ischemia (4,8,9). Although many patients had fixed or reversible perfusion defects in the present study, these perfusion abnormalities were not due to coronary artery disease of large epicardial arteries, because all patients had normal epicardial coronary arteries by coronary angiography. Therefore, the genesis of these ...

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 ...

Semantic Scholar extracted view of Effect of left ventricular hypertrophy on myocardial blood flow and ventricular performance in systemic hypertension. by Allen B. Nichols et al.

BACKGROUND: Non-ST elevation myocardial infarction (NSTEMI) is the commonest type of acute coronary syndrome (ACS) and has a poor long-term prognosis. Guidewire-based coronary pressure measurement of the myocardial fractional flow reserve (FFR) is a prognostically-validated invasive method for measuring coronary lesion severity in patients with stable coronary artery disease. FFR measurement in patients with unstable coronary disease has theoretical limitations and is not fully validated in NSTEMI.. AIM: To prospectively evaluate ischaemia and infarction with adenosine stress perfusion cardiac MRI in medically-stabilised NSTEMI patients in whom FFR has been measured.. METHODS: In the FAMOUS-NSTEMI clinical trial (NCT registration 01764334), medically-stabilised patients with recent NSTEMI will have lesion-level ischaemia measured with FFR in all coronary artery stenoses amenable to revascularisation, as clinically appropriate.. Consecutive study participants will be invited to have an adenosine ...

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

Figure 4 Coronary Function Versus Anatomy With Diffuse Coronary Artery Disease and Remodeling. (A) Schematic illustrating limitations of anatomic measures of stenosis severity by arteriogram (Artgm) or intravascular ultrasound (IVUS) due to diffuse disease with and without remodeling compared to coronary flow reserve. (B) For the schematic arteries illustrated in A, a scatter plot of coronary flow reserve (CFR) versus percent diameter stenosis (%DS) by arteriogram (brown diamonds) and by IVUS (yellow circles). The numbers beside each point of the scatter gram correspond to the numbered schematic examples of A. ...

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, ...

TY - JOUR. T1 - Pulsatile perfusion improves regional myocardial blood flow during and after hypothermic cardiopulmonary bypass in a neonatal piglet model. AU - Ündar, Akif. AU - Masai, Takafumi. AU - Yang, Shuang Qiang. AU - Eichstaedt, Harald C.. AU - McGarry, Mary Claire. AU - Vaughn, William K.. AU - Fraser, Charles D.. PY - 2002/1/1. Y1 - 2002/1/1. N2 - Pediatric myocardial related morbidity and mortality after cardiopulmonary bypass (CPB) are well documented, but the effects of pulsatile perfusion (PP) versus nonpulsatile perfusion (NPP) on myocardial blood flow during and after hypothermic CPB are unclear. After investigating the effects of PP versus NPP on myocardial flow during and after hypothermic CPB, we quantified PP and NPP pressure and flow waveforms in terms of the energy equivalent pressure (EEP) for direct comparison. Ten piglets underwent PP (n = 5) or NPP (n = 5). After initiation of CPB, all animals underwent 15 minutes of core cooling (25°C), 60 minutes of hypothermic CPB ...

TY - JOUR. T1 - Importance of maintaining systemic blood pressure during nitroglycerin administration for reducing ischemic injury in patients with coronary disease. Effects on coronary blood flow, myocardial energetics and left ventricular function. AU - Miller, Richard R.. AU - Awan, Najam A.. AU - DeMaria, Anthony N.. AU - Amsterdam, Ezra A. AU - Mason, Dean T.. PY - 1977. Y1 - 1977. N2 - Because of the controversy concerning the effects on myocardial ischemia of maintaining systemic pressure concomitant with administration of nitroglycerin, this study was undertaken of the actions of nitroglycerin, with and without simultaneous phenylephrine infusion, on coronary blood flow, myocardial energetics and left ventricular function in 17 patients with multivessel coronary artery disease. Five minutes after sublingual administration of 0.4 mg of nitroglycerin, mean arterial pressure, left ventricular filling pressure, cardiac index and coronary sinus blood flow were reduced (P , 0.05) from control ...

TY - JOUR. T1 - Fractional Flow Reserve/Instantaneous Wave-Free Ratio Discordance in Angiographically Intermediate Coronary Stenoses An Analysis Using Doppler-Derived Coronary Flow Measurements. AU - Cook, Christopher M.. AU - Jeremias, Allen. AU - Petraco, Ricardo. AU - Sen, Sayan. AU - Nijjer, Sukhjinder. AU - Shun-Shin, Matthew J.. AU - Ahmad, Yousif. AU - de Waard, Guus. AU - van de Hoef, Tim. AU - Echavarria-Pinto, Mauro. AU - van Lavieren, Martijn. AU - Al Lamee, Rasha. AU - Kikuta, Yuetsu. AU - Shiono, Yasutsugu. AU - Buch, Ashesh. AU - Meuwissen, Martijn. AU - Danad, Ibrahim. AU - Knaapen, Paul. AU - Maehara, Akiko. AU - Koo, Bon-Kwon. AU - Mintz, Gary S.. AU - Escaned, Javier. AU - Stone, Gregg W.. AU - Francis, Darrel P.. AU - Mayet, Jamil. AU - Piek, Jan J.. AU - van Royen, Niels. AU - Davies, Justin E.. PY - 2017/12/26. Y1 - 2017/12/26. KW - CFR. KW - coronary flow reserve. KW - coronary physiology. KW - FFR. KW - fractional flow reserve. KW - iFR. KW - instantaneous wave-free ...

Partial exhaustion of autoregulation can also cause a decrease in CFR in IDC for which there are 3 putative mechanisms, all of them based on compensatory vasodilation at rest. First, the decrease in MCD and capillary D result in increased capillary resistance that is compensated by some arteriolar and venular vasodilation to maintain normal resting coronary flow (Online Appendix). Second, increased wall stress in IDC leads to increased myocardial oxygen demand that is met by increased coronary flow via arteriolar and venular vasodilation. Finally, the central aortic (and arterial pressure) may be low in end-stage IDC, which could also cause arteriolar and venular dilation in order to maintain a constant myocardial capillary hydrostatic pressure.. CFR is related to the coronary driving pressure (ΔP, difference between mean aortic and right atrial pressures) according to the formula CFR = ΔP/(Qr × Rmin) where Qr is resting coronary flow and Rmin is the MVR during hyperemia. ΔP may decrease if ...

TY - JOUR. T1 - Frequency of Slow Coronary Flow Following Successful Stent Implantation and Effect of Nitroprusside. AU - Airoldi, Flavio. AU - Briguori, Carlo. AU - Cianflone, Domenico. AU - Cosgrave, John. AU - Stankovic, Goran. AU - Godino, Cosmo. AU - Carlino, Mauro. AU - Chieffo, Alaide. AU - Montorfano, Matteo. AU - Mussardo, Marco. AU - Michev, Iassen. AU - Colombo, Antonio. AU - Maseri, Attilio. PY - 2007/4/1. Y1 - 2007/4/1. N2 - Nitroprusside (NTP) is used for the treatment of slow coronary flow (SCF) after coronary interventions. The wide variation in dosage, route, and timing of its administration in the reported studies prevents an objective assessment of its efficacy. We report the incidence and response to a standardized NTP protocol of SCF after successful stent implantation. Selective intracoronary administration of incremental doses (initial bolus of 80 μg incremented by 40 μg) of NPT was assessed in 21 patients who developed SCF in a series of 2,212 consecutive patients who ...

TY - JOUR. T1 - Angina Due to Coronary Microvascular Disease in Hypertensive Patients without Left Ventricular Hypertrophy. AU - Brush, J. E.. AU - Cannon, R. O.. AU - Schenke, W. H.. AU - Bonow, R. O.. AU - Leon, M. B.. AU - Maron, B. J.. AU - Epstein, S. E.. PY - 1988/11/17. Y1 - 1988/11/17. N2 - When angina occurs in patients with hypertension, it is usually attributed to coronary artery disease or left ventricular hypertrophy. To determine the contribution of coronary microvascular abnormalities to angina in patients with hypertension, we evaluated hypertensive patients without coronary artery disease or left ventricular hypertrophy by measuring the coronary responses to rapid atrial pacing before and after administration of ergonovine. We compared 12 hypertensive patients who had pacing-induced angina with 13 normotensive subjects without such angina. The two groups had similar coronary flow (in the great cardiac vein) at rest; however, pacing increased coronary flow less in hypertensive ...

BACKGROUND AND PURPOSE: Current knowledge of the collateral circulation remains sparse, and a noninvasive method to better characterize the role of collaterals is desirable. The aim of our study was to investigate the presence and distal flow of collaterals by using a new MR perfusion territory imaging, vessel-encoded arterial spin-labeling (VE-ASL). MATERIALS AND METHODS: Fifty-six patients with internal carotid artery (ICA) or middle cerebral artery (MCA) stenosis were identified by sonography, VE-ASL was performed to assess the presence and function of collateral flow. The perfusion information was combined with VE maps into high signal-intensity-to-noise-ratio 3-colored maps of the left carotid, right carotid, and posterior circulation territories. The presence of the anterior and posterior collateral flow was demonstrated by the color of the standard anterior cerebral artery/MCA flow territory. The distal function of collateral flow was categorized as adequate (cerebral blood flow [CBF] >= ...

Coronary microvascular dysfunction (CMVD) is often suggested in patients with typical chest pain and abnormal stress test results that are indicative of myocardial ischemia, in who coronary angiography fails to show fixed stenosis in epicardial coron

Objective: To assess whether chronic treatment with carvedilol can increase myocardial blood flow (MBF) and MBF reserve in idiopathic dilated cardiomyopathy (IDC). Study design: In a double-blind, placebo-controlled trial, 16 consecutive patients with IDC were randomised to treatment with either carvedilol up to 25 mg twice a day (n = 8, 7 men, mean (SD) age 60 (9) years, mean (SD) left ventricular ejection fraction (LVEF) 30% (5%)), or placebo (n = 8 , 6 men, mean (SD) age 62 (9) years, mean (SD) LVEF 28% (6%), NS vs carvedilol group). Before and 6 months after treatment, regional MBF was measured at rest and after intravenous injection of dipyridamole (Dip; 0.56 mg/kg in 4 min) by positron emission tomography and using 13N-ammonia as a flow tracer. Exercise capacity was assessed as the time duration in a maximal bicycle exercise stress test. Results: Carvedilol induced a significant decrease in heart rate at rest and during maximal exercise, and an increase in exercise capacity. Absolute MBF ...

Coronary Microvascular Dysfunction, Left Ventricular Remodeling and Clinical Outcomes in Patients with Chronic Kidney Impairment. Circulation. 2019 Nov 29;: Authors: Bajaj N, Singh A, Zhou W, Gupta A, Fujikura K, Byrne C, Harms HJ, Osborne MT, Bravo P, Andrikopoulou E, Divakaran S, Bibbo CF, Hainer J, Skali H, Taqueti V, Steigner M, Dorbala S, Charytan DM, Prabhu SD, Blankstein R, Deo...

Cardiologists are learning more about coronary microvascular dysfunction, a cause of many previously unexplained cases of chest pain.

p,For patients with acute myocardial infarction (MI), the immediate therapeutic goal is to establish the patency of the infarct-related artery. Prolonged myocardial ischemia, however, often breaks down the coronary microvasculature, and the flow to the infarct myocardium may be markedly reduced. This is called the no-reflow phenomenon. This phenomenon is important not solely because it correlates with infarct size but because it provides additional prognostic information. With recent advances in imaging modalities, the no-reflow phenomenon is observed more frequently than when clinical judgment alone is used. Patients with this phenomenon are associated with poor functional and clinical outcomes. Now, the no-reflow phenomenon can be a parameter with which to predict high-risk patients. The focus of reperfusion therapy has shifted toward the improvement of myocardial perfusion. The improvement of myocardial perfusion could promote the functional recovery of viable muscle and reduce infarct ...

TY - JOUR. T1 - Relationship between surface area of nonperfused myocardium and extravascular extraction of contrast agent following coronary microembolization. AU - Malyar, Nasser M.. AU - Lerman, Lilach O.. AU - Gössl, Mario. AU - Beighley, Patricia E.. AU - Ritman, Erik L.. PY - 2011/8. Y1 - 2011/8. N2 - Myocardial microvascular permeability and coronary sinus concentration of muscle metabolites have been shown to increase after myocardial ischemia due to epicardial coronary artery occlusion and reperfusion. However, their association with coronary microembolization is not well defined. This study tested the hypothesis that acute coronary microembolization increases microvascular permeability in the porcine heart. The left anterior descending perfusion territories of 34 anesthetized pigs (32±3 kg) were embolized with equal volumes of microspheres of one of three diameters (10, 30, or 100 μm) and at three different doses for each size. Electron beam computed tomography (EBCT) was used to ...

TY - JOUR. T1 - Functional and structural alterations with 24-hour myocardial hibernation and recovery after reperfusion. T2 - A pig model of myocardial hibernation. AU - Chen, C.. AU - Chen, L.. AU - Fallon, J. T.. AU - Ma, L.. AU - Li, L.. AU - Bow, L.. AU - Knibbs, D.. AU - McKay, R.. AU - Gillam, Linda. AU - Waters, D. D.. PY - 1996/1/1. Y1 - 1996/1/1. N2 - Background: Short-term myocardial hibernation of 3 hours resulting from a moderate resting coronary flow reduction has been reproduced in pigs. This study was designed to determine whether any structural changes accompany short-term hibernation caused by a moderate flow reduction maintained for 24 hours and whether any such structural alterations are reversible after reperfusion. Methods and Results: A severe left anterior descending coronary artery (LAD) stenosis was created with a reduction of resting flow to ≃60% of baseline and maintained for 24 hours. Regional coronary flow was measured by a flowmeter; wall thickening was ...

The intra-aortic balloon pump (IABP) is a mechanical device that increases myocardial oxygen perfusion while at the same time increasing cardiac output. Increasing cardiac output increases coronary blood flow and therefore myocardial oxygen delivery. It consists of a cylindrical polyethylene balloon that sits in the aorta, approximately 2 centimeters (0.79 in) from the left subclavian artery and counterpulsates. That is, it actively deflates in systole, increasing forward blood flow by reducing afterload through a vacuum effect. It actively inflates in diastole, increasing blood flow to the coronary arteries via retrograde flow. These actions combine to decrease myocardial oxygen demand and increase myocardial oxygen supply. A computer-controlled mechanism inflates the balloon with helium from a cylinder during diastole, usually linked to either an electrocardiogram (ECG) or a pressure transducer at the distal tip of the catheter; some IABPs, such as the Datascope System 98XT, allow asynchronous ...

Over the entire MBF range (0.66-4.7 ml/min/g), concordance was excellent for MBF (r = 0.90, [(82)Rb-(15)O-water] mean difference ± SD = 0.04 ± 0.66 ml/min/g, LoA = -1.26 to 1.33 ml/min/g, ρ(c) = 0.88) and MFR (range 1.79-5.81, r = 0.83, mean difference = 0.14 ± 0.58, LoA = -0.99 to 1.28, ρ(c) = 0.82). Hyperaemic MBF was reduced in CAD patients compared with the subset of 11 control subjects (2.53 ± 0.74 vs. 3.62 ± 0.68 ml/min/g, p = 0.002, for (15)O-water; 2.53 ± 1.01 vs. 3.82 ± 1.21 ml/min/g, p = 0.013, for (82)Rb) and this was paralleled by a lower MFR (2.65 ± 0.62 vs. 3.79 ± 0.98, p = 0.004, for (15)O-water; 2.85 ± 0.91 vs. 3.88 ± 0.91, p = 0.012, for (82)Rb). Myocardial perfusion was homogeneous in 1,114 of 1,122 segments (99.3%) and there were no differences in MBF among the coronary artery territories (p , 0.31 ...

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BACKGROUND: The iPOWER study aims at determining whether routine assessment of coronary microvascular dysfunction (CMD) in women with angina and no obstructive coronary artery disease is feasible and identifies women at risk. METHODS: All women with angina referred to invasive angiographic assessment in Eastern Denmark are invited to join the study according to in- and exclusion criteria. Assessment includes demographic, clinical and psychosocial data, symptoms, electrocardiogram, blood- and urine samples and transthoracic echocardiography during rest and dipyridamol stress with measurement of coronary flow reserve (CFR) by Doppler of the left anterior descending artery. In substudies CMD will be assessed by positron emission tomography, peripheral endothelial function, magnetic resonance imaging-and computed tomography derived myocardial perfusion scans, angiographic corrected TIMI frame counts, advanced echocardiographic modalities at rest and during stress, and invasive measures of CFR and ...

We all know that early defibrillation and quality compressions are what matters in cardiac arrest. The end-point of compressions is generate cardiac output and coronary perfusion pressure.. Coronary perfusion pressure (CPP) is the difference between aortic diastolic pressure and the left ventricular end-diastolic pressure. In the working heart the coronary perfusion pressure is cycling between 0 and 70-80 mmHg. At least 60 mmHg or so is required for normal coronary blood flow.. When performing CPR we need to achieve a CPP of at least 15 mmHg in order to achieve ROSC. 15 mmHg certainly doesnt guarantee ROSC but thats how good our compressions need to be. There is an important paper in JAMA 1990 where Paradis et al demonstrated how a CPP of less than 15 mmHg resulted in 100% failure to resuscitate. With closed chest CPR we rarely achieve that outside the lab. Several studies report abysmal CPPs with averages ranging from 1-9 mmHg (1,2).. Here is where open chest direct heart compressions might ...

The development of coronary heart disease (CHD) is blunted by moderate levels of exercise training (EX). Mechanisms responsible for beneficial effects of EX are not known. The central theme of this Program Project Grant (PPG) is the hypothesis that EX is beneficial due to training- induced alterations in coronary vascular function. There are 3 major goals: A) elucidation of cellular molecular mechanisms for regulation of vascular smooth muscle (VSM) and endothelium in the coronary circulation, B) systematic determination of cellular/molecular mechanisms responsible for EX-induced changes in intrinsic vascular function, and C) application of this understanding of vascular cell biology and EX- induced coronary vascular adaptation to experimental models of CHD. The PPG formalizes and expands extensive collaborative efforts ongoing among this research team. An integrated experimental approach that examines coronary vascular function throughout the coronary tree of sedentary and EX pigs is presented. ...

Computer Analysis of Coronary Doppler Flow Velocity: 10.4018/978-1-59904-889-5.ch038: The coronary flow reserve (CFR) represents an important functional parameter to assess epicardial coronary stenosis and to evaluate the integrity of coronary

Methods and Results-Using intracoronary measurements, 91 coronaries (78 patients) with intermediate stenoses were classified in 4 FFR and coronary flow reserve (CFR) agreement groups, using FFR,0.80 and CFR,2 as cutoffs. Index of microcirculatory resistance (IMR) and atherosclerotic burden (Gensini score) were also assessed. MCD was assumed when IMR≥29.1 (75th percentile). Fifty-four (59.3%) vessels had normal FFR, from which only 20 (37%) presented both normal CFR and IMR. Among vessels with FFR,0.80, most (63%) presented disturbed hemodynamics: abnormal CFR in 28 (52%) and MCD in 18 (33%). Vessels with FFR,0.80 presented higher IMR [adjusted mean 27.6 (95% confidence interval, 23.4-31.8)] than those with FFR≤0.80 [17.3 (95% confidence interval, 13.0-21.7), p=0.001]. Atherosclerotic burden was inversely correlated with CFR (r=−0.207,P=0.055), and in vessels with FFR,0.80 and CFR,2 (n=28, 39%), IMR had a wide dispersion (7-72.7 U), suggesting a combination of diffuse atherosclerotic ...

Research presented at the Society of Nuclear Medicines 57th Annual Meeting is challenging the typical paradigm used to determine whether heart patients will benefit from invasive procedures like stent-placement or open-heart surgery. Current medical practice favors treating patients with coronary atherosclerosis (or hardening of the artery walls due to plaque build-up) with such procedures if a coronary artery is shown to be blocked by 70 percent or more in order to reduce symptoms and potentially prevent heart attack. However, a group of cardiac investigators are now finding that in addition to the degree of blockage, composition of the plaque causing the blockage also has significant impact on coronary artery blood flow. This may help explain why two people with similarly blocked coronary arteries can experience vastly different symptoms - ScienceDaily ...

Quantification of myocardial blood flow reserve in patients with CAD using real-time myocardial contrast echocardiography (RTMCE) has been demonstrated to further improve accuracy over the analysis of wall motion and qualitative analysis of myocardial perfusion.. Conventional stress echocardiography compares wall motion during rest and stress. The FDA has approved a contrast agent for use in patients with suboptimal echocardiograms, which accounts for up to 20% of resting echo studies. A suboptimal image is one in which at least two of six myocardial segments of the left ventricle cannot be visualized in the apical views. Contrast is used to opacify the LV chamber and to improve the delineation of the left ventricular endocardial border. Patient with suboptimal echoes include technically difficult patients, such as obese patients; patients undergoing mechanical ventilation; or patients with pulmonary hypertension.. Thomas R. Porter, MD, Chair of Cardiology at the University of Nebraska Medical ...

Cardiovascular disease is the leading cause of death worldwide. In the presence of signs and symptoms of myocardial ischaemia, women are more likely than men to have no obstructive coronary artery disease (CAD). Women have a greater burden of symptoms than men, and are often falsely reassured despit …

Olivey H.E., Svensson E.C.. The establishment of the coronary circulation is critical for the development of the embryonic heart. Over the last several years, there has been tremendous progress in elucidating the pathways that control coronary development. Interestingly, many of the pathways that regulate the development of the coronary vasculature are distinct from those governing vasculogenesis in the rest of the embryo. It is becoming increasingly clear that coronary development depends on a complex communication between the epicardium, the subepicardial mesenchyme, and the myocardium mediated in part by secreted growth factors. This communication coordinates the growth of the myocardium with the formation of the coronary vasculature. This review summarizes our present understanding of the role of these growth factors in the regulation of coronary development. Continued progress in this field holds the potential to lead to novel therapeutics for the treatment of patients with coronary artery ...

This hike is worth talking about as it takes you round some spectacular views in the Brecon Beacons.. When I did the hike round Cwm Gwesyn the guide books told us about waterfalls but you saw was actually very small - especially compared to the waterfalls seen on this hike between Ystradfellte and Pontneddfechan.. One of the highlights of the walk is the fact that you can walk under one of the waterfalls names Waterfall of the Snow. Gets a little wet though if you hang around underneath it for to long - like I did trying to take photos.. Taking this hike will also introduce you to waterfalls with delightful names like The Lady Waterfall and the Waterfall of the Chieftain.. ...

Comparison of exercise testing and CMR measured myocardial perfusion reserve for predicting outcome in asymptomatic aortic stenosis: the PRognostic Importance of MIcrovascular Dysfunction in Aortic Stenosis (PRIMID AS) Study ...