A total of 100 patients were studied for the diastolic blood pressure response to treadmill exercise testing. No change in the diastolic pressure or lowering of the pressure was considered normal response. Seventy-four patients had normal and 26 patients had abnormal diastolic blood pressure response. Forty patients underwent coronary angiography. ...

1. We previously reported that, although stimulation of coronary arterial baroreceptors results in reflex vasodilatation of a magnitude and a time course similar to that seen in response to carotid baroreceptor stimulation, the vasoconstriction that occurs when the stimulus to coronary baroreceptors is removed develops more slowly. We now report ...

BACKGROUND: Mechanisms underlying the initiation of ventricular arrhythmias in ischemia by a premature beat or after a pause remain unclear. The kinetics of electrical restitution, which is the modulation of action potential duration (APD) by an abrupt alteration in cycle length, may be important. METHODS AND RESULTS: We recorded one ...

The role of endothelin ETA and ETB receptors as well as of nitric oxide (NO) and prostanoids in the effects of endothelin-1 on the coronary circulation was studied in anesthetized goats. Where blood flow in the left circumflex coronary artery (coronary blood flow) (electromagnetically measured), systemic arterial pressure, left ventricle ...

BACKGROUND: Gallbladder distension in anesthetized pigs reflexly increases heart rate and arterial pressure by means of afferent vagal pathways and efferent sympathetic mechanisms. The effect of such distension on the coronary circulation is unknown. The present study was undertaken to determine whether gallbladder distension primarily causes reflex changes in left ...

The influence of passive vasomotion on the pressure drop-flow (delta P-Q) characteristics of a partially compliant stenosis was studied in an in vitro model of the coronary circulation. Twelve stenosis models of different severities (50 to 90 percent area reduction) and degrees of flexible wall (0 to 1/2 of the ...

We describe two patients who both suffered a cardiac arrest whilst maintained on an intra-aortic balloon pump. In an attempt to improve coronary and cerebral blood flow during cardiopulmonary resuscitation, the intra-aortic balloon was inflated to occlude the descending aorta and preferentially direct blood to the cerebral and coronary circulation. ...

The development of echo contrast agents that can provide reliable opacification of the myocardium after intravenous injection is an important advancement for the clinical application of contrast echocardiography. In this study, the hemodynamic effects and echocardiographic characteristics of a new lipid-fluorocarbon echo contrast agent, Aerosomes MRX 115 (ImaRx Pharmaceutical Corp., ...

In the externally perfused coronary bed of the isolated heart, LV elastance (Elv) rather than LV pressure (Plv) appears to be the major factor responsible for systolic coronary flow reduction, although effects of both have been demonstrated. However, normal perfusion in the presence of intact autoregulation in the heart in ...

To clarify the effect of left ventricular (LV) diastolic pressure on the coronary pressure-flow relation in humans, the instantaneous diastolic coronary pressure-Doppler flow velocity relation was analyzed at rest and during papaverine-induced maximal vasodilation in 15 patients with angiographically normal coronary arteries. The values for slope (alpha PF) and zero-flow ...

BACKGROUND: To assess coronary lesion severity in the catheterization laboratory, several guide wire-based methods have been proposed. The purpose of the present study was to compare the feasibility and the reproducibility of coronary flow velocity reserve (CFVR), instantaneous hyperemic diastolic velocity-pressure slope index (IHDVPS), and pressure-derived myocardial fractional flow reserve ...

1. Baroreflex responses to changes in aortic pressure were measured simultaneously in three main coronary regions of awake dogs. 2. Pulsed Doppler flow probes were mounted at prior surgery on the right, circumflex and anterior descending coronary arteries; the animals were placed in complete heart block and the left ventricle ...

OBJECTIVE: In vitro experiments have shown that an electric field changes coronary vascular resistance (CVR) tone and damages the vascular endothelium. The effect of transthoracic electric current in dogs on the vasodilatory responses mediated through the endothelium and reactive hyperemia were studied. The manner of delivery of the electric current ...

OBJECTIVES: To assess the effect of intravenous nitroglycerin (NTG) on segmental wall motion abnormalities (SWMAs) and global ventricular function after anesthetic induction in patients undergoing coronary artery bypass grafting (CABG). DESIGN: Prospective study. SETTING: University hospital. PARTICIPANTS: Twenty patients scheduled for elective CABG. INTERVENTIONS: Patients demonstrating SWMAs in at least ...

Acute increases in arterial pulsatile load imposed on the left ventricle can increase coronary flow without commensurate changes in myocardial oxygen consumption. One explanation is that augmenting pulsatile perfusion at the same mean pressure itself stimulates flow by releasing endothelium-mediated vasorelaxant factors such as NO. The present study tested this ...

A variety of compounds having a benzopyran such as levcromakalim generally exhibit potent antihypertensive activity. During extensive investigations aimed toward identifying K+ channel openers having selective coronary vasodilation without potent hypotensive and tachycardiac effects, we synthesized a series of 3,4-dihydro-2H-1-benzopyran-3-ol derivatives modified at positions 2, 4, and 6 in the ...

Increased cardiac perfusion results in increased oxygen consumption (VO2) and increased contractility (Gregg phenomenon) in the isolated heart. We investigated whether these two aspects of the Gregg phenomenon are related to coronary flow or arterial pressure. Coronary flow and, thus, arterial pressure were changed in the reference state and during ...

RATIONALE AND OBJECTIVES: The study was performed to clarify the mechanisms underlying contrast-induced coronary vasodilation. METHODS: The left anterior descending coronary artery of 14 open-chest dogs was perfused at constant pressure. Coronary blood flow (CBF) was measured electromagnetically and used to calculate myocardial oxygen consumption (MVO2). Responses were evaluated during ...

The effect of afterload during regional ischaemia on myocardial stunning was studied in 15 pentobarbital anaesthetized cats. 10 min occlusion of the left anterior descending artery (LAD) was followed by 60 min of reperfusion. Afterload was decreased by intravenous infusion of nitroglycerine 3-8 micrograms kg-1 min-1 in group I (n ...

Coronary vasoconstriction is a component of the baroreflex response to bilateral carotid occlusion. The central pathways responsible for this reflex constriction are incompletely understood, but previous studies show that activation of parabrachial nucleus (PBN) elicits coronary vasoconstriction and that PBN shares prominent anatomic connections with other central baroreflex centers, including ...

OBJECTIVE: We compared the effects of diastolic coronary sinus pressure elevation due to synchronized retroperfusion (SRP) with systolic coronary sinus pressure elevation due to coronary sinus occlusion on the coronary pressure-flow relationship under similar mean coronary sinus pressure values. METHODS: Using isolated, perfused canine hearts, coronary perfusion of the left ...

Perfusion balloon catheters are designed to provide continuous transcatheter blood flow and thereby reduce myocardial ischemia during coronary angioplasty. To compare the transcatheter flow rates of active and passive (auto-) perfusion catheters, a well-controlled experimental study was performed in a circulation model that duplicates the phasic, predominantly diastolic flow pattern ...

We studied the impeding effect of cardiac muscle contraction on coronary arterial inflow in six isolated, perfused papillary muscles of the rat. Special attention was given to the effect of changes in muscle length and contractility on flow impediment in systole. Contractility was changed by resumption of pacing after a ...

OBJECTIVE: To assess the response of internal mammary artery (IMA) flow of hypertensive hearts to nitroprusside infusion. METHODS: Fifteen patients were studied with a high-frequency duplex Doppler probe from the supraclavicolar approach. All the patients had undergone coronary artery bypass surgery with an IMA graft into the left anterior descending ...

AIM: To study the effect of phencyclidine (Phe) on dog coronary artery. METHODS: Contraction of spiral strips of dog coronary artery in bioassay and coronary artery blood flow (CBF) using electromagnetic flowmeter on anesthetized dogs were observed. RESULTS: Phe 0.1-100 mumol.L-1 induced contraction of strips in a concentration-dependent manner. Dextromethorphan ...

BACKGROUND: The rate of adaptation of coronary blood flow in response to stepwise changes in heart rate (HR) has been extensively studied in dogs and goats to improve our understanding of the dynamics of coronary regulation processes and their pathophysiology and to obtain time constants for mathematical modeling of the ...

To date, no clinical study shows an improvement in coronary flow reserve due to long-term antihypertensive therapy. in view of the contribution of the renin-angiotensin system to the process of hypertensive remodeling of the heart and coronary circulation, angiotensin-converting enzyme (ACE) inhibitors might act as cardioreparative drugs in arterial hypertension. ...

The rapid intravenous administration of 10 ml of sterile water or hypotonic saline to five conscious sheep induced substantial adverse haemodynamic effects lasting 10 to 20 seconds. They included reductions in cardiac output (to 44 per cent of the baseline value measured in the 30 seconds before the injection), arterial ...

BACKGROUND: The University of Wisconsin solution has been proven to be effective for prolonged heart preservation. However, 24-hour heart preservation by simple cold immersion in University of Wisconsin solution has been disappointing. We have performed hypothermic low-pressure continuous coronary perfusion with oxygenated University of Wisconsin solution for experimental prolonged heart ...

1. The hypothesis that inward rectifier K(+) channels are involved in the vasodilatation of small coronary and cerebral arteries (100-200 microm diameter) in response to elevated [K+]o was tested. The diameters and membrane potentials of pressurized arteries from rat were measured using a video-imaging system and conventional microelectrodes, respectively. 2. ...

BACKGROUND: [corrected] Age is an independent risk factor for increased mortality from ischemic heart disease. Arterial stiffening with widening of the pulse pressure may contribute to this risk by exacerbating cardiac dysfunction after total coronary artery occlusion. METHODS AND RESULTS: To test the above hypothesis, 14 open-chest dogs underwent surgery ...

BACKGROUND: Endogenous production of bradykinin (BK) has been postulated to cause hemodynamic changes and cardiac pain during myocardial ischemia, presumably because of the stimulation of cardiac afferent fibers. METHODS: To test the hypothesis that BK results in cardiac reflex responses and can cause the sensation of angina, 10 patients with ...

1. Mongrel dogs were chronically instrumented with an intra-aortic catheter, a Königsberg intraventricular pressure transducer and a Döppler flow probe around the left coronary artery. After ganglionic blockade with hexamethonium, the cardiovascular effects of bradykinin B1 and B2 receptor agonists, des-Arg9-bradykinin and bradykinin (BK), were investigated in the presence and ...

Myocardial perfusion measurement with colored microspheres may become an alternative for radioactive microsphere techniques. We use and validate a spectrophotometric method that has been previously established for large animals in the isolated perfused rat heart. The perfusion system was adapted for use in a NMR microscope. Hearts were perfused with ...

Coronary pressure flow (P/F) relationship has been investigated mainly from the viewpoint of coronary resistance. However, recent experimental evidence suggests that the zero flow pressure intercept (Pzf) provides important characteristics of coronary circulation. Although Pzf is likely to provide meaningful information about characteristics of coronary circulation, no data are available ...

The systemic and coronary hemodynamic effects of the nitrovasodilator, pirsidomine, were compared with SIN-1, nitroprusside, and nitroglycerin. Four groups consisting of 32 experiments were performed in 17 conscious dogs chronically instrumented for measurement of aortic and left ventricular pressure, left ventricular dP/dtmax, diastolic coronary blood flow velocity, cardiac output, and ...

1. Systemic and coronary haemodynamics were measured in 6 Yorkshire swine and 6 Yucatan miniature swine under isoflurane anaesthesia to investigate the influence of cocaine following its intravenous administration at 1, 3 and 7 mg kg-1. 2. Cocaine in Yorkshire swine decreased mean arterial pressure and rate pressure product (systolic ...

Oscillating pressure inflations may minimize trauma to the coronary artery during coronary angioplasty. We measured in vitro diameters of polyolepin copolymer compliant angioplasty balloons (as a surrogate for pressure) during pressure oscillation at the inflator to determine if pressure oscillations at the inflator were conducted to the balloon. Balloon diameter ...

Nitric oxide plays an important role in the control of basal coronary tone and mediation of reactive hyperaemic flow response following short-term coronary occlusion. The results presented in this report indicate that NO is involved in the modulation of coronary autoregulation in isolated rat hearts. Isolated rat heart exhibit autoregulation ...

Disopyramide reduces the subaortic pressure gradients and improves the clinical symptoms of patients with hypertrophic obstructive cardiomyopathy. Changes in coronary hemodynamics and vasodilator reserve in response to this agent have not been evaluated in such patients. To assess the acute effects of intravenous administration of disopyramide on coronary hemodynamics, microvascular ...

In this work we tried to perform a dynamic analysis of coronary vascular response to histamine, using a simple mathematical analysis as a first step in the better understanding of complex histamine effects on coronary blood vessels of the isolated guinea pig heart. So, we defined more parameters, such as: ...

The aim of this study was to evaluate the role of endogenous histamine in the regulation of reactive hyperaemia (RH) and coronary autoregulation in isolated rat hearts. The basal release of cardiac histamine (perfusion pressure 60 cm H2O) amounted to 100-200 pmol/min/g wt. During the first 15 s following 30 ...

The aim of this study was to investigate the effect of Iloprost (Schering AG), a stable prostacyclin analogue, on the intensity of thiobarbituric acid-reactive substances (TBARS), conjugated diene and hydroperoxide production in ischaemic dog myocardium. Adult male mongrel dogs were divided into groups as follows: A = sham/operated group, B ...

The effects of soman (pinacolyl methylphosphonofluoridate) on coronary blood flow, the electrocardiogram, and cardiac function were measured in alpha-chloralose-anesthetized swine. Coronary blood flow (CBF), mean arterial blood pressure (MAP), peak systolic left ventricular pressure (IVP), maximum rate of left ventricular pressure development (dP/dtmax), cardiac output, and the ECG were monitored ...

This study examined why an artery becomes vulnerable to spasm when used as a bypass graft. We hypothesized that high flow demands would decrease pressure distally in the conduit (afterload), thus increasing the sensitivity to vasoconstrictors. Furthermore, perioperative endothelial dysfunction would additionally sensitize the artery to constrictors. Six gastroepiploic arteries ...

To attempt to explain the loss of subendocardial coronary reserve in chronic pressure-overload cardiac hypertrophy on a morphologic basis, we measured capillary capacity and coronary artery and arteriole medial wall area in dogs with moderately severe chronic (1 year) left ventricular hypertrophy (LVH). Aortic bands were placed on the ascending ...

Our objective was to evaluate methodological aspects of impedance planimetry, a new balloon catheter-based technique, for the investigation of coronary artery mechanical wall properties. We used a four ring-electrode electrical impedance measuring system that was located inside a balloon. Two of the electrodes were used for excitation and connected to ...

OBJECTIVES: The importance of NO-induced vasodilator tone in maintaining adequate coronary flow to sustain hemodynamic function in aerobically perfused heart and the role of NO in the injury development in ischaemic/reperfused heart was studied. METHODS: Effect of NO synthesis inhibitor (N omega-nitro-L-arginine, L-NOARG) on isolated working rat hearts subjected to ...

Translesional pressure and flow velocity observations in the right coronary artery remain among the most difficult data to interpret because of variation in the location and relative size of branches, and unsuspected diffuse disease. Use of distal hyperemic response and translesional pressure gradients provides the most accurate assessment of serial ...

The effect of stunning on endothelium-dependent responses of resistance vessels in vivo remains of interest. We utilized the coronary pressure-flow relationship during maximal vasodilation in anesthetized swine to identify subtle changes in flow reserve within stunned myocardium. Prior to and following stunning, the coronary pressure-flow relationship during maximal doses of ...