BACKGROUND: Autoperfusion balloons are available for the protection of the myocardium during balloon angioplasty. The aortic pressure is the driving force that delivers blood to the distal vessel during balloon inflation. Autoperfusion balloons can achieve sufficient flow rates in vitro. The use of these devices is recommended in high-risk patients ...

Estrogen therapy is associated with a 50% reduction in the clinical manifestations of coronary artery disease in postmenopausal women. Attenuation of coronary vasomotor dysfunction may contribute to estrogen's cardioprotective effects. We hypothesized that conjugated estrogens, which contain several vasoactive estrogenic compounds, may favorably influence the vasomotor response to acetylcholine in ...

Adenosine triphosphate (ATP) is reported to be released mainly from presynaptic vesicles and cardiomyocytes. The released ATP, which can be degraded to adenosine, may cause coronary vasodilation. However, there is no clear evidence that ATP is degraded to adenosine and causes coronary vasodilation in humans. The present study was undertaken ...

OBJECTIVE: The present study was performed to compare coronary flow reserve by transesophageal Doppler echocardiography and intracoronary Doppler flow wire measurements in patients with LAD disease. METHODS: 17 patients with various degree of LAD stenosis were studied. Intracoronary LAD Doppler measurements were performed at baseline and after intracoronary injection of ...

The aim of this study was to assess whether active coronary perfusion catheters (APC) can provide a sufficient coronary flow in large caliber vessels during balloon inflation. To prevent myocardial ischemia during PTCA, these APC may be employed. However, it is as yet unknown whether the active flow rate of ...

OBJECTIVES: This study sought to evaluate coronary vasomotor response to percutaneous transluminal coronary angioplasty (PTCA) and its influence on proximal and distal vessel diameters with regard to stenosis severity and coronary blood flow. BACKGROUND: Coronary vasoconstriction of the distal vessel segment has been reported after PTCA. This vasoconstrictive effect was ...

The objective was to investigate how the blood flows in the thoracic aorta, with special emphasis on flow reversal and flow into the coronary arteries. Three-directional MR velocity mapping was used to map multidirectional flow velocities in the aorta in 14 normal subjects and 14 patients with coronary artery disease. ...

The aim of the study was to analyze the relationship between antegrade and collateral flow degree to the "culprit" coronary artery, and between both variables and left ventricular systolic function. We analyzed five hundred patients with acute myocardial infarction, treated prospectively and consecutively within 6 h of evolution with intravenous ...

BACKGROUND: Changes in intramyocardial blood volume (IBV) mediate autoregulatory adaptations to coronary stenosis. This study investigated whether (1) myocardial contrast echocardiography (MCE) can quantify changes in IBV during coronary stenosis and (2) the relation between coronary resistance- and MCE-derived IBV could yield insight into structural mechanisms of IBV change. METHODS ...

The coronary reactive hyperemic response was examined in seven pigs under anesthetized and conscious conditions, (i.e., 5 days and 3 and 5 weeks after surgery). Tygon catheters were inserted in the descending aorta of five pigs; transonic flow probes and hydraulic occluders were placed on the left cranial descending and/or ...

OBJECTIVE: Estrogen receptors have been found in coronary arterial endothelial and vascular smooth muscle cells. Therefore the present study was designed to determine if estradiol-17 beta can increase coronary blood flow and if so whether the changes are mediated by nitric oxide. STUDY DESIGN: Five oophorectomized non-pregnant sheep were chronically ...

Adenosine has been postulated to be the physiological transmitter coupling increases in coronary blood flow to increases in myocardial metabolism. The purpose of this experiment was to evaluate the role of adenosine in the coronary hyperemia due to norepinephrine. In 11 anesthetized, closed-chest canine preparations, the left main coronary artery ...

Estrogen induces the generation of nitric oxide (NO) and produces coronary vasodilation by opening the Ca2+-activated K+ (K[Ca]) channels. The hypothesis that 17beta-estradiol produces NO and activates K(Ca) channels during coronary hypoperfusion was investigated. In open-chest dogs, the left anterior descending coronary artery was perfused through an extracorporeal bypass tube ...

OBJECTIVES: This study was undertaken to examine the relation of in vivo low density lipoprotein (LDL) oxidation and other lipid risk factors to coronary reactivity in normal subjects. BACKGROUND: Experimental studies have shown that oxidized LDL (ox-LDL) particles are injurious to the vascular wall by impairing its normal vasodilator function. ...

We hypothesized that blood flow to collateralized and noncollateralized myocardium is improved by antagonism of endothelin (ET) A receptors. Coronary collateral development was stimulated by placing an ameroid constrictor around the left circumflex coronary artery (LCx; collateralized region) in 11 swine. After 35 +/- 2 days, the left anterior descending ...

This study was designed to evaluate the alterations in doppler derived coronary blood flow velocities and flow reserve following rotational ablation. Changes in doppler derived coronary blood flow velocity variables have been valuable in assessing the physiological outcome following coronary balloon angioplasty. Rotational ablation's mechanism of plaque removal could alter ...

OBJECTIVES: This study was designed to evaluate the hemodynamic variables of the collateral circulation during acute coronary occlusion. BACKGROUND: There is limited information on the physiology of the collateral circulation in coronary artery disease. METHODS: Angiography of the contralateral donor artery was performed before and during balloon coronary occlusion in ...

OBJECTIVES: To test the hypotheses: that acute administration of 17 beta-estradiol dilates normal coronary microvessels in vivo; that coronary microvascular responses to acute estrogen stimulation exhibit sexual dimorphism; and that nitric oxide has a role in mediating these effects. METHODS: Measurements of hemodynamics, coronary flow velocity (Doppler), myocardial blood flow ...

The objectives of this study were to evaluate the use of high-frequency (5 MHz) transthoracic echocardiography for the noninvasive measurement of coronary blood flow and to test its ability to detect small changes in blood flow that may accompany pharmacologic intervention. High-frequency (5 MHz) transthoracic echocardiography was performed on the ...

OBJECTIVE: Breath-hold velocity-encoded cine (VENC) MR imaging has been proposed as a method for measuring coronary blood flow. However, most studies have measured velocity rather than volume flow rate in the coronary arteries. The purpose of this study was to measure volume flow rate in the coronary artery of dogs ...

We have developed dynamic intravenous coronary arteriography (IVCAG) using a monochromatic (33.3 keV), 2-dimensional X-ray beam (70 x 70 mm) generated from synchrotron radiation. To investigate its use to visualize the coronary arteries and to estimate coronary blood flow, we performed IVCAG in 10 dogs and 1 goat. The animals ...

OBJECTIVE: Previous evidence suggests that episodes of myocardial ischemia of sufficient duration and intensity are required to produce coronary collateral development during repetitive coronary occlusion. This investigation tested the hypothesis that coronary collateral development is also temporal-dependent. METHODS: Chronically instrumented dogs (n = 16) were subjected to brief (2 min) ...

OBJECTIVE: Endothelin-1 (ET) is a potent endogenous vasoconstrictor which has been shown to be increased following ischaemia and cardiopulmonary bypass. We tested the hypothesis that inhibition of ET synthesis during cardioplegic arrest using phosphoramidon (an ET converting enzyme inhibitor) or blockade of ET receptors using bosentan (a mixed ET(A)/ET(B) antagonist), ...

BACKGROUND: The role of cardiac sympathetic nerves in regulating coronary blood flow is controversial. We sought to determine the degree to which cardiac efferent sympathetic signals modulate coronary blood flow. The heterogeneous sympathetic reinnervation in transplanted hearts provides a model for studying the vasomotor responses to adrenergic stimulation in reinnervated ...

In this overview, currently available clinical methods to measure flow in the coronary circulation will be discussed. Methods only applicable in the experimental laboratory or in the anaesthetized patient during cardiac surgery, will not be described. We distinguish between methods that measure global blood flow, and methods that determine regional ...

Objective evidence for coronary lesion significance can be obtained with ischemic stress testing. Since flow-limiting stenoses have already undergone compensatory vasodilatation to maintain flow, the response to vasoactive stimulation is dampened. The degree of response limitation is reflected by the coronary flow reserve (CFR). Absolute volume flow rates can be ...

OBJECTIVES: The objectives of this study were to define physiologic effects on and a clinical correlate to coronary blood flow during volume unloading surgery in patients with aortic atresia. METHODS: Twenty-two patients with aortic atresia (group I, 13 patients with stage I reconstruction undergoing hemi-Fontan operation; group II, 9 patients ...

Small-volume resuscitation using hypertonic saline (7.5%) is effective for various types of shock. Recently, hypertonic saline has been proposed for fluid management in patients with impaired cardiovascular function. Whether hypertonic saline is safe in the compromised heart during coronary occlusion is not known. We examined the effects of hypertonic saline ...

BACKGROUND: In order to ascertain whether human adenosine-induced dilatation of epicardial arteries is direct or flow-mediated, we compared the effects of intracoronary adenosine infusion on epicardial coronary arteries with those produced by dipiridamole, a selective arteriolar vasodilator. METHODS AND RESULTS: In 24 patients with angiographically normal coronary arteries, coronary blood ...

RATIONALE AND OBJECTIVES: The authors present an angiographic method to measure absolute coronary blood flow in patients. METHODS: The left or right coronary tree is three-dimensional (3D)-reconstructed from biplane coronary angiograms. This allows the determination of the intravascular volumes needed for flow measurement. The 3D distance traveled by the contrast ...

BACKGROUND: The purpose of this study was to assess serial changes in coronary blood flow velocity before and after Rotablator atherectomy and after adjunctive percutaneous transluminal coronary angioplasty (PTCA). Since Rotablator atherectomy results in luminal enlargement by plaque pulverization and distal embolization, improvement in coronary blood flow could be attenuated ...

OBJECTIVE: Are substances released from rat coronary endothelial cells responsible for the increase in contractility and oxygen consumption (Gregg phenomenon) seen with an increase in cardiac perfusion? METHODS: In an isovolumically contracting, Langendorff, crystalloid perfused rat heart (n = 6) at 27 degrees C, coronary flow was changed (from 4.4 ...

In the dog it has been shown that, while the inhibition of the endothelial release of nitric oxide reduces the duration, the total hyperaemic flow and the peak flow of the acetylcholine and myogenic coronary vasodilator responses, in the reactive hyperaemia the peak is not affected. The difference has been ...

BACKGROUND: This study was undertaken to compare the coronary vasodilator response to different application modalities of intravenous vasodilators, in order to identify the optimal pharmacological protocol for the evaluation of coronary reserve by means of transoesophageal Doppler echocardiography. METHODS: Blood flow velocity in the left anterior descending artery, coronary vascular ...

BACKGROUND: Currently used methods for assessment of coronary flow reserve are invasive and require extensive laboratory equipment. Recently, noninvasive assessment of coronary flow reserve by transesophageal Doppler evaluation of coronary sinus (CS) or left anterior descending coronary artery (LAD) flow has been proposed. Direct comparison between these two techniques is ...

The impact of guiding catheter selection on the measurement of coronary flow reserve was assessed by injecting increasing doses of adenosine through 3 different catheters often used during coronary interventions. When guiding catheters with side holes were used, an approximate doubling of the adenosine dose was required to produce a ...

Quantitative hemodynamic assessment during various endovascular interventions including balloon angioplasty is lacking. Translesional pressure drops measured by angioplasty catheters can cause flow blockage and thus lead to inaccurate estimates of preintervention and postintervention flow rates. A new analytical model of the flow rate-pressure drop relation across vascular stenoses is utilized ...

This study was designed to compare the effect of a mechanical vs a pharmacologic increase in BP on coronary artery blood flow and thrombolysis induced by IV administration of recombinant tissue plasminogen activator. We employed a canine model of coronary thrombosis induced by injection of radioactive blood clot in the ...

OBJECTIVES: Coronary collateral flow often mitigates the effects of coronary artery obstruction and has a significant impact on the prognosis of patients with coronary artery disease. In the presence of variable degrees of coronary collateral flow, digital radiographic assessment of myocardial blood flow has not been quantitatively validated. METHODS: A ...

The effect of intravenous administration of the endothelium derived vasoconstrictor peptide endothelin-1 (ET-1 0.2. 1 and 8 pmol kg-1 min-1) on coronary blood flow in relation to plasma ET-1 as well as blood lactate and glucose levels were investigated in six healthy volunteers. Coronary sinus blood flow was measured by ...

The initial in-hospital and long-term clinical experience with a helical autoperfusion balloon catheter in the treatment of coronary artery disease is reported. This new catheter design allows blood to flow passively around the inflated balloon through a protected helical channel molded into the balloon surface. Twelve consecutive patients underwent PTCA. ...

Several acutely acting antimigraine drugs, including ergotamine and sumatriptan, have the ability to constrict porcine arteriovenous anastomoses as well as the human isolated coronary artery. These two experimental models seem to serve as indicators, respectively, for the therapeutic and coronary side-effect potential of the compounds. Using these two models, we ...

PURPOSE: It was the purpose of this study to demonstrate the feasibility of performing coronary artery flow and coronary flow reserve (CFR) measurements in normal human volunteers using a magnetic resonance (MR) phase contrast technique. MATERIALS and METHODS: Coronary flow rate, flow velocity, peak flow and CFR were determined at ...

Doppler velocimetry with the use of transesophageal echocardiography can record flow in the proximal left anterior descending artery (LAD). To assess whether this limited sampling ability influences the recording of velocity and the calculation of coronary flow reserve (CFR), 32 patients with LAD stenosis (4 ostial stenoses, 18 proximal stenoses, ...

This review article discusses some of the potentially beneficial effects of calcium antagonists on the coronary microcirculation. These include their vasodilating action on coronary resistance vessels as well as their effects on extravascular resistance (i.e. intramyocardial pressure). Examples are presented of how the non-invasive measurement of myocardial blood flow and ...

BACKGROUND: This study compares the effects of cold blood and crystalloid cardioplegia on adrenergic and myogenic regulation of the coronary circulation. METHODS: Pigs were placed on cardiopulmonary bypass and hearts were arrested with a hyperkalemic crystalloid cardioplegic solution (Cryst CP) or blood cardioplegic solution (Blood CP) for 1 hour. Hearts ...

In isolated rabbit hearts perfused with suspension of red blood cells, we investigated the role of the endothelium and of several substances in the coronary vasoconstriction induced by a high arterial blood oxygen tension (PaO2). Red blood cells in Krebs-Henseleit buffer were oxygenated to obtain control and high-PaO2 perfusates. Arterial ...

These preclinical studies investigate a new concept in coronary angioplasty and balloon catheter technology (the P100 catheter). The study sought to evaluate the morphology of experimental coronary arterial plaques dilated with the P100 in comparison to standard balloons, to determine the in vitro flow rates occurring during the inflation of ...

Blood flow to perfuse the muscle cells of the heart is distributed by the capillary blood vessels via the coronary arterial tree. Because the branching pattern and vascular geometry of the coronary vessels in the ventricles and atria are nonuniform, the flow in all of the coronary capillary blood vessels ...

Ischaemic injury in a number of animal models is reduced by mivazerol (2-hydroxy-3-[(1-H-imidazol-4-yl) methyl]-benzamide, CAS 125472-02-8). This effect was accompanied by a reduction in heart rate. The effect of mivazerol on myocardial blood flow and lactate production in the ischaemic myocardium was examined at constant heart rate by right atrial ...