Search Results
Results 301 - 350 of 1551
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Traverse J H - - 2001
OBJECTIVE: The increase in coronary blood flow (CBF) in response to endothelium-dependent vasodilators is reduced in congestive heart failure (CHF) suggesting endothelial dysfunction. However, increases in extravascular compressive forces secondary to elevated left ventricular diastolic pressure (LVEDP) in CHF might contribute to this abnormality. METHODS: We measured CBF responses to ...
Cornelissen A J - - 2001
We investigated the influence of stretch on regional hemodynamic parameters of the septal circulation. We used a similar experimental setup and mathematical model, as described previously (14). Five ventricular septa were isolated from anesthetized dogs, sutured to a biaxial stretching apparatus, and perfused with an oxygenated perfluorochemical emulsion at maximal ...
Claeys M J - - 2001
Fractional flow reserve (FFR) has been applied with success as a lesion-specific functional indicator of stenosis severity, at least in patients with normal microcirculation. This study sought to assess the reliability of FFR calculations in patients with associated microvascular dysfunction (e.g., post myocardial infarction, or post-MI). First, the effect of ...
Wright M J - - 2001
Clinical reports suggest that intracoronary delivery of adenoviruses encoding angiogenic growth factors, or their transactivators, has a therapeutic benefit. However there has not been a systematic assessment of the transfection efficiency of this technique in vivo. In rabbits we investigated the efficiency of myocardial gene transfer following intracoronary infusion of ...
Crockett T R - - 2001
The effects of the endothelin ET(A), (BQ-123) and endothelin ET(A/B) (PD161721) receptor antagonists were investigated on ischaemia-induced arrhythmias and on the maximum following frequency. The study was carried out in Langendorff perfused rat hearts subjected to coronary artery occlusion in which the severity of arrhythmias, coronary perfusion pressure and heart ...
Pace L - - 2001
It is known that contractile reserve may be blunted if perfusion and coronary flow reserve are reduced. Thus, it is conceivable that the predictive accuracy of dobutamine echocardiography may differ according to perfusion tracer uptake. The aim of this study was therefore to assess the relationship between the level of ...
Ulgen M S - - 2001
The aim of this study is to investigate the value of hemodynamic changes induced by carotid sinus massage (CSM) on the diagnosis of coronary artery disease (CAD). A total 108 patients (mean age, 54 +/- 10 years, range 33-70) who had no significant stenosis in the carotid artery by duplex ...
Cunha F N - - 2001
The increase in right ventricular systolic pressure observed in vivo after the administration of mercury opposes to the idea that the metal depresses the cardiac pump performance. We then investigated the effects of HgCl(2) (0.1 to 2.5 microM) on the contractile activity of the right ventricular myocardium, measuring isometric and ...
Shalman E - - 2001
Arterial stenosis is known to be one of the most serious cardiovascular diseases. Angiographical estimation of arterial stenosis provides limited information on the severity of the occlusion and the flow of blood through it. Hemodynamical assessment of the flow and pressure behaviour, is known to be clinically important. Hemodynamically based ...
Nanto S - - 2001
The present study seeks to estimate the difference between coronary zero flow pressure (Pzf) by analysis of the baseline pressure-flow relationship and the Pzf calculated during a long diastole in humans. Although Pzf is likely to provide meaningful information about the characteristics of coronary circulation, there are no available data ...
Kitakaze M - - 2001
We tested the hypothesis that cellular acidosis modulates the production of nitric oxide (NO) in ischemic hearts. In canine hearts, we decreased coronary blood flow (CBF) to one third of the control by reduction of coronary perfusion pressure (105+/-3 to 41+/-5 mmHg), and thereafter we maintained CBF constant (89.8+/-1.6 to ...
English J A - - 2001
The angiographic prevalence, clinical predictors, and sensitivity and specificity of a bilateral arm blood pressure differential for predicting proximal left subclavian artery stenosis were established in 492 patients undergoing cardiac catheterization. Seventeen subjects (3.5%) in the overall population and nine subjects (5.3%) with potential surgical coronary disease had proximal left ...
Ural D - - 2001
In some hypertensive patients, echocardiographic examination does not reveal any pathologic finding in spite of a documented blood pressure elevation. In our study, we investigated the effect of preload reduction with Valsalva manoeuver on transmitral flow velocities in hypertensive patients with normal mitral flow pattern and compared the results with ...
Lee B K - - 2001
The objective of the present study was to evaluate the hemodynamic characteristics of an atherosclerosis-prone coronary artery compared to the aorta. We describe three- dimensional spatial patterns of wall shear stress (WSS) according to the impedance phase angle in pulsatile coronary and aorta models using in vivo hemodynamic parameters and ...
Kassab G S - - 2001
We have determined the cross-sectional area (CSA) compliance of the first several generations of pig coronary arteries and the volume compliance of the coronary arterial tree (vessels >0.5 mm in diameter) using a videodensitometric technique. The coronary arteries of four KCl-arrested maximally vasodilated pig hearts were perfused with iodine and ...
Wagner J A - - 2001
Activation of peripheral cannabinoid CB(1) receptors elicits hypotension. Using the radioactive microsphere technique, we examined the effects of cannabinoids on systemic hemodynamics in anesthetized rats. The potent cannabinoid CB(1) receptor agonist HU-210 ([-]-11-OH-Delta(9) tetrahydrocannabinol dimethylheptyl, 10 microg/kg i.v.) reduced mean blood pressure by 57+/-5 mm Hg by decreasing cardiac index ...
Schwemmer M - - 2001
Recently the new specific phosphodiesterase-5 inhibitor sildenafil was introduced into therapy for erectile dysfunction. Because of the phosphodiesterase-5 inhibitor-induced increases of cyclic GMP in the vasculature, vasodilation in various vascular beds is induced, which in combination with various nitrovasodilators (e.g., when used simultaneously for the treatment of coronary artery disease), ...
Nair B A - - 2001
1. Previous reports indirectly implicate a neural mechanism for coronary constriction to centrally administered digitalis. However, autoregulatory changes in coronary resistance due to changes in arterial pressure may have influenced the interpretation of these studies. 2. We tested directly the hypothesis that cardiac sympathetic innervation is responsible for coronary constriction ...
de Marchi S F - - 2001
Little is known about the vasomotor function of human coronary collateral vessels. The purpose of this study was to examine collateral flow under a strong sympathetic stimulus (cold pressor test, CPT). In 30 patients (62 +/- 12 years) with coronary artery disease, two subsequent coronary artery occlusions were performed with ...
Tamborini G - - 2001
BACKGROUND: In essential hypertension, the lower limit of autoregulation of coronary flow shifts to higher perfusion and the hypertensive ventricle is at a higher than normal risk of ischemia, and less able to tolerate acute reduction of coronary perfusion pressure. Little is known about pattern of coronary flow in isolated ...
Zheng D - - 2001
The temporal relationship between the systemic and myocardial concentrations of magnesium and some of its acute cardiovascular effects were examined after short i.v. infusion administration of magnesium (30 mmol over 2 min) in five awake chronically instrumented sheep. Magnesium decreased mean arterial blood pressure and systemic vascular resistance (SVR) by ...
Takayama T - - 2001
This study was performed to determine whether three-dimensional intravascular ultrasound (3D IVUS) could predict the physiologic significance of coronary lesions. Seventeen lesions were evaluated by means of 3D IVUS, pressure measurements, and quantitative coronary angiography. Physiologic parameters were calculated from the 3D IVUS measures using established equations and compared to ...
Briguori C - - 2001
Myocardial fractional flow reserve (FFR) < 0.75 is a reliable index of a functionally severe coronary stenosis. FFR is best assessed by a sensor-tipped pressure monitoring guidewire (PW). The purpose of this study was to assess whether a multifunctional probing catheter (MFP), a 3 French dual-lumen monorail catheter, can be ...
Yano M - - 2001
The influence of timing and magnitude of arterial wave reflection (WR) on afterload-dependent relaxation was evaluated in patients with a variety of heart diseases (group 1, age < 30 yr; group 2, age > 40 yr) and in dogs. While both femoral arteries were compressed (FC), WR returned just after ...
Merkus D - - 2001
The presence of a coronary stenosis results primarily in subendocardial ischemia. Apart from the decrease in coronary perfusion pressure, a stenosis also decreases coronary flow pulsations. Applying a coronary perfusion system, we compared the autoregulatory response of subendocardial (n = 10) and subepicardial (n = 12) arterioles (<120 microm) after ...
Hughes P - - 2001
OBJECTIVES: In many heart centers myocardial revascularization using beating heart coronary surgery has partly replaced conventional coronary artery bypass grafting (cCABG) using cardiopulmonary bypass. However, access to the marginal arteries is problematic and hampered by space limitations, which might compromise the quality of the anastomoses and it entails a significant ...
Huang C H - - 2001
BACKGROUND: The pressure waveform of coronary sinus in human hearts has never been well described. Retrograde cardioplegia perfusion has become a popular method of myocardial protection in recent years, and identification of the pressure waveform of the coronary sinus might help intubate the coronary sinus in retrograde cardioplegia perfusion by ...
Wang W - - 2001
Our previous study (27) showed that the cardiac sympathetic afferent reflex (CSAR) was enhanced in dogs with congestive heart failure. The aim of this study was to test whether blood volume expansion, which is one characteristic of congestive heart failure, potentiates the CSAR in normal dogs. Ten dogs were studied ...
Cmolik B L - - 2001
BACKGROUND: We hypothesized that diastolic counter-pulsation using aortomyoplasty will increase coronary blood flow. METHODS: In dogs (n = 6, 20 to 25 kg), the left latissimus dorsi muscle was isolated, wrapped around the descending thoracic aorta, and conditioned by chronic electrical stimulation. Heart failure was induced by rapid ventricular pacing. ...
Molinari C - - 2001
The present study was designed to investigate the effect of progesterone on the coronary circulation and to determine the mechanisms involved. In pigs anaesthetized with sodium pentobarbitone, changes in left circumflex or anterior descending coronary blood flow caused by intravenous infusion of progesterone at constant heart rate and arterial blood ...
He S - - 2001
RATIONALE AND OBJECTIVES: The authors performed this study to (a) investigate coronary movement with electron-beam computed tomography (CT) and (b) find the optimal electrocardiographic (ECG) triggering phase for eliminating motion artifact. MATERIALS AND METHODS: One hundred fifty-one patients without arrhythmia were examined with electron-beam CT. First, movie scans were obtained ...
Ejaz T - - 2001
Changes in the subendo-subepi flow ratio were studied by using a simple electronic circuit model of the coronary vessel consisting of a resistor, capacitor and field effect transistor in order to provide a better understanding of the ischemic vulnerability of the subendocardium. The simulated subendo-subepi flow ratio was found to ...
Gras J - - 2000
Almotriptan is a new 5-HT(1B/1D) receptor agonist effective for treating acute migraine attacks with or without aura. As 3-5% of patients treated with sumatriptan experience chest symptoms thought to be of cardiac origin, we investigated the cardiovascular safety profile of almotriptan in comparison with that of sumatriptan in six animal ...
Oldenburg O - - 2000
Calcium antagonists are used in interventional cardiology to prevent coronary vasoconstriction or to overcome the no-reflow phenomenon. The aim of the current study was to evaluate the dose-dependent effects of intracoronary verapamil on systemic and coronary hemodynamics. In 20 patients scheduled for routine coronary angiography, heart rate, blood pressure, and ...
Sambuceti G - - 2000
To verify the interaction between coronary pressure (CP) and blood flow (CBF) control, we studied nine candidates for angioplasty of an isolated lesion of the left anterior descending coronary artery [i.e. , percutaneous transluminal coronary angioplasty (PTCA)]. CBF (i.e., flow velocity x coronary cross-sectional area at the Doppler tip) and ...
Dimitrow P P - - 2000
Impaired endothelium-dependent vasodilatation of coronary resistance vessels has been demonstrated in patients with hypertrophic cardiomyopathy (HC). The aim of this study was to compare the effect of verapamil and propranolol on the response of diastolic coronary blood flow velocity (CBFV) and coronary vascular resistance index to the cold pressor test ...
Porges W L - - 2000
1. The Darwin hypothesis that human and animal expressions of emotion are the product of evolution and are tied to patterns of autonomic activity specified to progress the emotion remains under challenge. 2. The sigh is a respiratory behaviour linked with emotional expression in animals and humans from birth to ...
Aldea G S - - 2000
Increasing pressures to 30 mmHg in right (RV) and left (LV) ventricles and surrounding heart (SH) in isolated, arrested, maximally vasodilated, blood-perfused dog hearts shifted pressure-flow (PF) curves rightward and increased zero flow pressure (P(zf)) by an amount equal to the RV applied pressure, SH applied pressure, or two-thirds of ...
Krabatsch T - - 2000
Today there is no doubt that angina in patients with diffuse end-stage coronary artery disease can be treated effectively by transmyocardial laser revascularization (TMLR). But until now, the underlying mechanism of TMLR is a matter of debate. The aim of this study was to investigate the immediate changes in functional ...
Ishikura F - - 2000
BACKGROUND: Sildenafil citrate (Viagra) is indicated for the treatment of erectile dysfunction. Large and sudden decreases in systemic blood pressure were reported in a substantial number of patients taking sildenafil citrate combined with nitroglycerin. We studied the effect of sildenafil citrate on the relationship between changes in systemic blood pressure ...
Pijls N H - - 2000
BACKGROUND: When several stenoses are present within 1 coronary artery, the hemodynamic significance of each stenosis is influenced by the presence of the other(s), and the calculation of coronary and fractional flow reserve (CFR and FFR) for each individual stenosis is confounded. Recently, we developed and experimentally validated a method ...
Abe M - - 2000
BACKGROUND: Coronary blood flow occurs mainly during the diastolic phase of each cardiac cycle and is mainly dependent on diastolic driving pressure, especially in the left anterior descending coronary artery (LAD). We hypothesized that calculation of the ratio of the diastolic driving pressure of a stenotic LAD to its normal ...
Bach R - - 2000
This single-center, prospective, randomized, double-blind phase IV study with parallel-group design was performed to test whether injection of a newly designed non-ionic monomeric radiographic contrast medium in the axillary artery influences the ipsilateral cutaneous microcirculation. Twenty patients with coronary heart disease or suspected coronary heart disease were investigated. Ten patients ...
Rouleau J R - - 2000
The renin-angiotensin system plays a critical role in regulating vasoconstriction and vasodilatation that can influence myocardial blood flow and its transmural distribution. We tested the hypothesis that angiotensin inhibition can induce a leftward shift of the coronary autoregulatory pressure-flow relation and preserve distribution of myocardial blood flow at lower coronary ...
Wright C - - 2000
Previous studies which have indicated that the stimulation of ventricular mechanoreceptors induces significant reflex responses can be criticised because of the likelihood of concomitant stimulation of coronary arterial baroreceptors. We therefore undertook this investigation to examine the coronary and ventricular mechanoreflexes in a preparation in which the pressure stimuli to ...
Watanabe N - - 2000
BACKGROUND AND METHODS: In order to elucidate the underlying adjusting mechanism of human right coronary arterial (RCA) flow to increased right ventricular pressure (RVP) in children, we recorded RCA flow velocity in 24 pediatric cardiac patients at the orifice of its main trunk at the time of heart catheterization using ...
Shen Y T - - 2000
Thrombosis resulting from blood platelet aggregation via glycoprotein (GP) IIb/IIIa receptor activation triggers the local release of vasoactive substances. Therefore, inhibition of these receptors could affect coronary vasoactive function during thrombotic coronary arteriostenosis. Twenty pigs were instrumented with an aortic catheter and with hydraulic occluders and flow probes on both ...
Mathison M - - 2000
BACKGROUND: Coronary artery bypass grafting on the beating heart causes significant hemodynamic compromise during displacement of the heart. The precise mechanisms causing altered hemodynamics have not been clearly understood. The purpose of this study was to define the hemodynamic changes caused by displacing the heart in patients undergoing beating heart ...
György K - - 2000
The effects of the intracoronary administration of isosorbide-2-mononitrate (ISMN; 3 microg kg(-1) min(-1)), a major metabolite of isosorbide dinitrate, were examined in chloralose-urethane anaesthetized dogs before and during a 25 min, acute occlusion of the left anterior descending coronary artery. The only significant haemodynamic effects of ISMN administration were a ...
Lorbar M - - 2000
The aim of this study was to establish whether epicardial transudates could be used to uncover small, but physiologically important changes in interstitial NE concentrations under normal and pathological conditions. Norepinephrine (NE) concentrations measured in epicardial transudate fluid were compared to NE levels in the coronary effluent in normal and ...
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