Several models purported to represent hibernating myocardium involve a coronary stenosis (CS) to reduce blood flow (BF) and function without eliciting necrosis in anesthetized pigs. The goal of the present study was to determine whether sustained moderate reduction in coronary BF in conscious pigs induced hibernating myocardium, ie, perfusion-contraction matching ...

This study examined the effects of different atrioventricular (AV) intervals, during AV sequential pacing, on hemodynamics and coronary blood flow in individuals with normal hearts. Left anterior descending artery blood flow velocity was measured, using intracoronary Doppler, in 17 normal individuals. Five pacing tests were applied in random order for ...

OBJECTIVES: To develop a technique for automatic inflation of a percutaneous transluminal coronary angioplasty (PTCA) balloon, with continuous measurement of the balloon pressure and volume; to validate the technique for determining the mechanical characteristics of coronary arteries. METHODS: During necropsy examination of the hearts of nine patients, 17 coronary artery ...

Studies were undertaken for a mathematical analysis of reactive hyperaemia in the isolated rat heart with and without electrical pacing and the introduction of a new parameter i.e., rate of reactive hyperaemia, to evaluate reactive hyperaemia. Rate of reactive hyperaemia is represented as a change of coronary perfusion pressure in ...

We examined the systemic and coronary hemodynamic effects of five combinations of R- and S-verapamil enantiomers (R/S; 100/0, 90/10, 80/20, 50/50, and 20/80%, respectively) in conscious dogs chronically instrumented for measurement of aortic and LV pressure, +dP/dt, subendocardial segment length, coronary blood flow velocity, and aortic blood flow. Dogs received ...

A 50-yr-old man developed constrictive pericarditis following an episode of acute pericarditis. Cardiac catheterization revealed a typical early diastolic dip and plateau configuration in both the right and left ventricular pressure curves. The coronary flow velocity pattern determined using an intracoronary Doppler guidewire showed an abrupt decrease in peak velocity ...

BACKGROUND: Left ventricular (LV) diastolic function and coronary flow are impaired in hypertrophic obstructive cardiomyopathy (HOCM). This study was designed to evaluate the impact of cardiac and circulatory ACE inhibition on such derangements. METHODS AND RESULTS: Twenty patients with HOCM underwent cardiac ACE inhibition with intracoronary (IC) enalaprilat (0.05 mg/min ...

OBJECTIVE: Brain death induces important haemodynamic changes in rats, with a drop in arterial blood pressure, left ventricular developed pressure and dP/dtmax to less than 50% of its control value. Myocardial damage was reported to contribute to this paradigm. The role of potential underlying pathogenetic mechanisms, such as a circulating ...

BACKGROUND: Acupuncture is reported to reduce myocardial ischemia, arrhythmias, and hypertension. To investigate the physiological mechanisms underlying these observations, a model of reflex-induced, reversible myocardial ischemia was developed to test the effects of median nerve stimulation as a surrogate for electroacupuncture. METHODS AND RESULTS: Chloralose-anesthetized cats were instrumented to measure ...

OBJECTIVE: The sensitive relationship between regional myocardial perfusion and local systolic deformation during acute myocardial ischemia is not independent of the transmural location or segment orientation. The aim of this study was to determine the effects of fiber orientation and transmural location on the relationships between regional myocardial flow and ...

The capacitative properties of the major left coronary arteries, left main (LM), left anterior descending (LAD), and left circumflex (LCX), were studied in 19 open-chest isolated dog hearts. Capacitance was determined by using ramp perfusion and a left ventricular-to-coronary shunt diastolic decay method; both methods gave similar results, indicating a ...

OBJECTIVES: Myocardial ischemia plays a central role in the development of right ventricular failure after acute pulmonary embolism. This study investigates whether pulmonary mediators act specifically on coronary tone and cardiac contractile function in acute pulmonary microembolization and whether such effects are altered in the case of early systemic atherosclerosis. ...

The present study shows that isolated, perfused hearts from rats orally infected with Trichinella spiralis have a reduced left ventricular developed pressure (LVDP), heart rate (HR) and coronary flow (CF). This reduction is considerably enhanced by a single bolus (100 pM) of PAF (platelet activating factor, an eosinophil activator), especially ...

The goal of the present study was to compare two common types of isolated working mouse heart models, setting afterload either with (1) a hydrostatic fluid column, or (2) a mechanical resistor. Cardiovascular function in both models was determined by volume- and pressure-loading protocols. During volume loading, both models demonstrated ...

Coronary vascular responses to acetylcholine (ACh, 3 micrograms/kg i.v.), nitroglycerin (NTG, 25 micrograms/kg i.v.), and a 20-s coronary artery occlusion (reactive hyperemia, RH) were investigated in seven conscious dogs with severe left ventricular (LV) hypertrophy and chronic coronary pressure overload (CCPO) due to supravalvular aortic banding and in seven control ...

Coronary venous hypertension induced by partial coronary sinus obstruction (CSO) in the dog, prevents or delays the predictable ventricular fibrillation (VF) of the early phase of acute ischemia. Also, CSO acting presumably through enhanced myocardial hydration, normalizes the inhomogenous extracellular potassium ([K+]o) accumulation, a major factor in producing the electrophysiological ...

The effect of nicardipine hydrochloride (NIC, CAS 54527-84-3, Perdipine) on myocardial metabolism was investigated in an experimental model of ischemic acute heart failure (AHF) induced by coronary ligation in anesthetized dogs. The left anterior descending and/or circumflex coronary ligation decreased coronary sinus blood flow (CBF), maximum rate of rise of ...

Pentobarbital-anesthetized dogs were instrumented for hemodynamic measurements and cooled by heat exchange tubes. Through a catheter in the coronary sinus, blood samples were obtained and plasma leukotrienes measured using a high-pressure liquid chromatography technique. Hemodynamic function was significantly reduced during cooling, and during subsequent rewarming hemodynamic function was only partly ...

BACKGROUND: In some patients with chronic stable angina the beneficial effects of nitrates may result not only from a reduction in venous return, but also from their action on coronary circulation. In these patients, rate-pressure product at ischemia (RPPI) increases to > 2500 bpm x mmHg after sublingual nitrates (SLN). ...

The reduction of coronary mortality is not as large as one would expect from the observed blood pressure lowering in trials of antihypertensive medications. This is not surprising; hypertension is a complex disease where the high blood pressure is only one of numerous coronary risk factors. Sympathetic overactivity in hypertension, ...

The purpose of this study was to investigate effects of tetramethylpyrazine (TMP), a Chinese plant-derived medicine, on coronary vasoconstriction and related electrocardiographic and histologic changes caused by endothelin-1 (ET-1), and on plasma ET-1 levels. ET-1 (75 pmol) was administered into the left coronary artery (LCA) in anesthetized closed-chest dogs with ...

The question was addressed whether short-term (4 hour) NO deficiency, inducing an increase in blood pressure in anaesthetized dogs, does influence proteosynthesis in the myocardium and coronary arteries. A potentially positive answer was to be followed by the study of the supporting role of ornithine decarboxylase for the polyamines pathway. ...

The treatment of choice in patients with drug-resistant atrioventricular nodal reentry tachycardia is radiofrequency fast or slow pathway ablation. Ablation of the reentrant circuit in the region of the His bundle, when approached from the anterior-superior region (fast pathway); can result in complete AV block. This is less likely if ...

Structurally and pharmacologically diverse vasodilators are known to lower blood pressure, increase heart rate, and produce acute injury to right coronary arteries in the dog. Administration of low concentrations of endothelin-1 (ET-1) to anesthetized dogs causes coronary vasoconstriction and reductions in coronary blood flow. Therefore, pharmacologic blockade of endothelin receptors ...

This study was designed to investigate the retrograde arterial pressures in the distal ends of the superior thyroid (n = 20) and facial arteries (n = 8). These pressures were compared with mean systemic arterial pressure (n = 20) as well as retrograde pressure in the radial artery (n = ...

The objective of this study was to determine the effect of systemic MgSO4 infusion on subendocardial and subepicardial perfusion. Seventeen spontaneously breathing piglets were examined. Myocardial perfusion was measured using radiolabeled microspheres at baseline, 30 and 60 min after either MgSO4 (80 mg/kg) or saline infusion. Blood pressure, heart rate, ...

BACKGROUND: The purpose of this study was to evaluate the hemodynamic mechanisms leading to myocardial ischemia in patients with myocardial bridging. Myocardial bridging is known to induce angina and even severe myocardial ischemia. METHODS AND RESULTS: In 12 symptomatic patients with myocardial bridges, quantitative coronary angiography was performed to obtain ...

In anesthetized pigs, we investigated whether asynchrony (delta T) and nonuniformity (regional differences) in contractility (delta E) could describe the interaction between normal and stunned myocardium. Mechanical interaction was evaluated by regional postsystolic work (PSW) before and after production of stunning by a 5-min occlusion of the left circumflex coronary ...

OBJECTIVE: After the Fontan operation the right atrium and, thus, the coronary sinus are connected to the pulmonary arterial system, which causes the coronary venous pressure to increase. We investigated the acute effects of elevation of coronary venous pressure on baseline hemodynamics, coronary venous flow, and left ventricular contractility. METHODS: ...

The effect of the nitric oxide donor ITF 1129 and nitroglycerin (NTG) on myocardial blood flow was examined in dogs with a Doppler velocity probe, hydraulic occluder, and indwelling microcatheter in the left anterior descending coronary artery (LAD). Studies were performed during treadmill exercise in the presence of a coronary ...

PURPOSE: Repeat balloon angioplasty is likely to induce intimal proliferation, which is associated with a higher restenosis rate. This study examined the effect of intracoronary ionizing radiation on restenotic lesions using repeat balloon injury in a normolipemic swine. METHODS AND MATERIALS: Eight domestic normolipemic pigs underwent overstretch balloon angioplasty with ...

BACKGROUND: The comparative effects of calcium channel blockers and ACE inhibitors on myocardial blood flow (MBF) in hypertensive patients after long-term treatment are still unknown. METHODS AND RESULTS: Twenty hypertensive subjects with normal coronary arteries were randomly assigned to verapamil 240 to 480 mg/d or enalapril 10 to 40 mg/d. ...

The purpose of this research was to test whether the positive inotropic and antiarrhythmic effects of bradykinin are due solely to increases in coronary flow. Rat hearts were perfused at constant pressure (75 cm H2O) and temperature (37 degrees C). Coronary flow was measured using an electronic drop counter. Contractile ...

BACKGROUND: Although isoflurane may cause subendocardial hypoperfusion in the presence of coronary stenosis because of its coronary arteriolar dilatory effects, it is not known how the subendocardial microcirculation is affected. The authors examined the effects of isoflurane on poststenotic subendocardial microvessels with coronary stenosis. METHODS: The authors observed subendocardial microvessels ...

Monocytes are activated during collateral artery growth in vivo, and monocyte chemotactic protein-1 (MCP-1) has been shown to be upregulated by shear stress in vitro. In order to investigate whether MCP-1 enhances collateral growth after femoral artery occlusion, 12 rabbits were randomly assigned to receive either MCP-1, PBS, or no ...

BACKGROUND: In the selection of patients eligible for minimally invasive coronary artery bypass grafting (MICABG), knowledge about the pathophysiologic significance of individual coronary stenoses is important. Only if the lesion amenable to MICABG can be identified as the culprit lesion, and other lesions can be demonstrated not to be responsible ...

AIM: To develop a new catheter-based method of treatment in patients with hypertrophic obstructive cardiomyopathy. METHOD: Does abolition of the blood supply to the subaortic part of the septum lead to regional myocardial ischaemia and a decrease in the left ventricular outflow tract gradient? To find this out, in 10 ...

The present study was undertaken in anaesthetized pigs to determine whether distension of the uterus reflexly affects the aortic blood pressure, heart rate, left ventricular inotropic state and the coronary circulation. Experiments were performed in 17 pigs anaesthetized with alpha-chloralose and artificially ventilated. Coronary blood flow was measured with an ...

Recent evidence suggests that newer vasoselective dihydropyridine calcium antagonists are not cardiodepressant and may be useful in the treatment of heart failure. No data are available on the efficacy of clentiazem, a vasoselective benzothiazepine-like calcium antagonist, in this pathological condition. Therefore, our objective was to assess coronary and cardiac sensitivity ...

BACKGROUND: Alpha 2-adrenergic agonists have peripheral vasoconstrictive effects and central sympatholytic and sedative effects. Whereas the latter are the basis of their use in anesthesia, the former could limit their clinical application. METHODS: To study whether a vasodilator could alleviate the systemic and coronary vasoconstrictor effects of dexmedetomidine without influencing ...

BACKGROUND: 8-ornithine-vasopressin (ornipressin, POR-8) is used as a potent peripheral vasoconstrictor mainly in combination with local anaesthetics. Because ornipressin causes vasoconstriction, any myocardial depressive effects could be caused indirectly by reduced myocardial perfusion secondary to coronary vasoconstriction, or directly by effects on myocardial tissue. METHODS: On isolated guinea pig hearts, ...

Models of coronary arterial trees are generated by the algorithm of constrained constructive optimization (CCO). In a given perfusion area a binary branching network of straight cylindrical tubes is generated by successively adding terminal segments to the growing structure. In each step the site of connection is chosen according to ...

Many fungal products are known to possess biological activity towards the mammalian tissues. We studied vasodilating activity in the crude ethanol extract of the dried mycelia of Basidiomycetes sp. YL8006, cultured by submerged fermentation with a complex medium. The activity was assayed using the isolated perfused rat heart in the ...

A mechanism by which acetylcholine (ACh) may elicit vasoconstrictor response in coronary vessels was studied in rat hearts perfused at a constant flow rate. In spontaneously beating hearts, bolus injections of ACh and carbachol (CCh) produced biphasic changes in coronary perfusion pressure (CPP): a transient increase at the initial period ...

The time course of the effects of intravenous or intracoronary administration of peptide leukotrienes on metabolic parameters and on systemic and coronary hemodynamics was evaluated in 15 patients with normal coronary arteries. Peptide leukotriene C4 (2 nmol given as a bolus intravenous injection) induced an early fall (at 2 min) ...

The effects of intravenous (iv) bolus administrations of bradykinin (0.1-1 microgram.kg-1) on large and small coronary arteries were investigated in seven chronically instrumented conscious dogs. Bradykinin dose-dependently increased heart rate, left ventricular dP/dt max, coronary blood flow and coronary artery diameter and decreased aortic pressure. Subchronic inhibition of the nitric ...

8-Arginine vasopressin (AVP) is a powerful coronary vasoconstrictor as well as peripheral vasoconstrictor, but AVP also is reported to have negative cardiac inotropic and chronotropic effects in vitro and in vivo. Our aim was to examine the direct effects of coronary vasoconstriction by AVP on cardiac function and metabolism in ...

Recent advances in genetic methods permit the introduction of random and defined mutations into the mouse germ line, producing novel mouse strains, some of which affect the heart and vasculature. A TTR-ANF transgenic strain of mice, which constitutively expresses a fusion gene consisting of the transthyretin promoter and the ANF ...

Our goal was to develop a new method to evaluate coronary flow reserve independent of perfusion pressure by equipping dogs with a Doppler flow probe in the left anterior descending artery. The slope of the linear portion of the velocity-pressure loop in the late diastolic phase was defined as VP ...

Thrombin's cellular actions are mediated by a novel G-protein coupled transmembrane receptor. We infused SFLLRN, a peptide that directly activates thrombin receptors, into the left circumflex coronary artery (CFX) of anesthetized dogs to evaluate the cardiovascular effects of thrombin receptor activation in vivo. Intracoronary SFLLRN, 0.9, 9 and 90 nmol/min, ...