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Results 251 - 300 of 1560
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Jang S S Department of Biomedical Engineering, Health Science College, Yonsei University, Wonju, South - - 2004
This work presents an alternative return of spontaneous circulation (ROSC) estimate using indirectly induced presumption that coronary perfusion pressure (CPP) correlates with the extracted parameter from the ventricular fibrillation (VF) ECG signal. In past studies, it is revealed that successful cardiopulmonary resuscitation (CPR) needs at least 30 approximately 40 mmHg ...
Voudris Vassilis - - 2003
BACKGROUND: Changes in mean blood pressure (MBP) alter coronary blood flow (CBF). We evaluated the acute effects of three hypotensive medications on CBF parameters in angiographically normal coronary arteries. METHODS: We performed CBF measurements using the Doppler wire at rest and during hyperemia produced by intracoronary adenosine (18 microg) as ...
Agnisola C - - 2003
Basal performance, volume loading response and oxygen consumption were determined in a resistance-headed preparation of the isolated trout heart. Two groups of hearts were used: the +CF group, in which the coronary vascular tree was perfused with a flow directly related to the pressure generated by the heart, and the ...
Cin V Gökhan - - 2003
Intravascular ultrasound imaging can detect intimal thickening and is suitable for detection of early atherosclerosis, which cannot be detected by conventional angiography. The aim of the present study was to investigate the epicardial coronary morphology and intracoronary pressure in relation to slow coronary flow (SCF). The study population consisted of ...
Boersma Eric - - 2003
BACKGROUND: Elevated blood pressure is associated with an impaired prognosis in patients with established coronary heart disease. Adequate blood pressure control is therefore of utmost importance. We report on two successive European surveys that evaluated whether the goals given in recommendations on secondary prevention are achieved. METHODS: The first European ...
Houghton Jan Laws - - 2003
Excess coronary heart disease morbidity and mortality among African Americans remains an important yet unexplained public health problem. We hypothesized that adverse outcome is in part due to intrinsic or acquired abnormalities in coronary endothelial function and vasoreactivity. We compared dose-response curves relating changes in coronary blood flow and epicardial ...
Hamza Leila H - - 2003
The objective of this study was to determine the effect of passive myocardium on the coronary arteries under distension and compression. To simulate distension and compression, we placed a diastolic-arrested heart in a Lucite box, where both the intravascular pressure and external (box) pressure were varied independently and expressed as ...
Malo Olivier - - 2003
Coronary endothelial dysfunction in left ventricular hypertrophy (LVH) can reduce myocardial perfusion and result in an impaired global LV function. The objective of this study was to characterize the specific alterations of endothelial signal transduction of coronary arteries in a swine LVH model. Aortic banding was performed 3 cm above ...
Casella G - - 2003
BACKGROUND: Fractional flow reserve (FFR) is a measure of coronary stenosis severity that is based on pressure measurements obtained at maximal hyperemia. Therefore, achievement of maximal vasodilatation of the coronary microcirculation is a prerequisite for the measurement of FFR. The study was designed to address the hypothesis that intracoronary adenosine ...
Escaned Javier - - 2003
OBJECTIVES: This study reports a comparative assessment of the hemodynamic relevance of myocardial bridges (MB) using two modalities of fractional flow reserve (FFR), with and without concomitant inotropic challenge. BACKGROUND: Extravascular coronary compression by means of MB is modulated by myocardial inotropism and causes intracoronary systolic pressure overshooting and negative ...
Beaucage Pierre - - 2003
Calcium channel blockers (CCBs) have variable efficacy in the treatment of heart failure. We hypothesized that modulation of left ventricular diastolic pressure (LVDP) may play a role in the variable efficacy of CCBs in this condition. Isolated perfused hearts from 200- to 250-day-old UM-X7.1 cardiomyopathic hamsters (failing hearts) and age-matched ...
Kozàkovà Michaela - - 2003
OBJECTIVES: High pulsatile load is associated with structural alterations of the heart and arteries, which may cause changes in the coronary circulation and predispose to myocardial ischemia. This study was designed to investigate the relationships of coronary vasodilator capacity and exercise-induced myocardial ischemia to pulsatile and steady components of office ...
Fearon William F - - 2003
BACKGROUND: A relatively simple, invasive method for quantitatively assessing the status of the coronary microcirculation independent of the epicardial artery is lacking. METHODS AND RESULTS: By using a coronary pressure wire and modified software, it is possible to calculate the mean transit time of room-temperature saline injected down a coronary ...
Rajappan Kim - - 2003
BACKGROUND: Increased extravascular compression and reduced diastolic perfusion time (DPT), rather than vascular remodeling, influence coronary microcirculatory dysfunction in aortic stenosis (AS). However, alterations after aortic valve replacement (AVR) remain unclear. The aim of the present study was to quantify changes in transmural perfusion and coronary vasodilator reserve (CVR), a ...
Ronson Russell S - - 2003
BACKGROUND: Pharmacologically potentiated electrical stimulation of the right vagus nerve achieves controlled intermittent asystole cardiac therapy. The present study examined pathophysiologic consequences of repetitive intermittent asystoles on contractile function, myocardial blood flow, and vagus nerve function and morphology. METHODS: Open-chest anesthetized canines, with either normal left anterior descending (LAD) coronary ...
Tanaka Nobuhiro - - 2003
To assess the coronary flow velocity - pressure relationship distal to a stenosis, and to evaluate the influence of microvascular abnormalities on this relationship, coronary flow velocity and coronary pressure were measured simultaneously in 38 patients (42 vessels). The instantaneous peak coronary flow velocity was plotted against the simultaneous measured ...
Akasaka Takashi - - 2003
OBJECTIVES: This study sought to assess the reliability of pressure-derived coronary flow reserve (CFR) compared with flow- or velocity-derived CFR. BACKGROUND: Coronary flow reserve has been reported to have important clinical implications for the evaluation and treatment of coronary artery disease. METHODS: Using a pressure guide wire, coronary pressure distal ...
Hong Cheng - - 2003
PURPOSE: To evaluate the effects of different thresholds and quantification methods on the accuracy and reproducibility of coronary calcium measurements with multi-detector row computed tomography (CT). MATERIALS AND METHODS: A cardiac CT phantom containing predetermined calcified cylinders was scanned. Calcium volume and mass were measured at various threshold values ranging ...
Beltran E - - 2003
Lipid oxidation of pressurized (300 and 500 MPa for 30 min at 20 °C) or cooked (90 °C for 15 min) minced chicken breast and slurries was evaluated. Mechanical processing, before and after pressurization and cooking, and addition of sodium chloride were also tested as prooxidant factors. At 1, 3, 6 and ...
Cho Sungsam - - 2003
The hemodynamic interaction of dantrolene, a specific drug for malignant hyperthermia, and propofol which appears to be safe in malignant hyperthermia-susceptible patients, has not been investigated. We performed this study to examine the hemodynamic actions of dantrolene at a therapeutic dose during propofol anesthesia. Ten dogs were chronically instrumented for ...
Laham Roger J - - 2003
This study was designed to investigate the site of vascular endothelial growth factor (VEGF)-induced vasodilation in the systemic and coronary vasculature. Intracoronary infusion of VEGF in Yorkshire pigs resulted in a significant drop in the mean arterial blood pressure, with a decline in the left ventricular left end-diastolic pressure, and ...
Molinari C - - 2003
Extensive research suspecting an association between plasma levels of dehydroepiandrosterone and the risk of coronary heart disease has not been conclusive. The present study was designed to investigate the effect of dehydroepiandrosterone on the coronary circulation and to determine the mechanisms involved. In prepubertal pigs of both sexes anaesthetized with ...
Kim W G - - 2003
We report a comparison of the effects of myocardial infarction in dogs and sheep using sequential ligation of the left anterior descending artery (LAD) and its diagonal branch (DA), with hemodynamic, ultrasonographic and pathological evaluations. Five animals were used in each group. After surgical preparation, the LAD was ligated at ...
Kamiya Hiroyuki - - 2003
We developed a coronary active perfusion system (CAPS) to avoid myocardial ischemia during off-pump coronary artery bypass (OPCAB). The purpose of this study was to determine the optimal timing of CAPS perfusion, and to investigate any adverse effects when it is driven within the systolic phase. Twenty-four pigs were divided ...
Sibelius Ulf - - 2003
OBJECTIVE: hemolysin has been implicated as an important pathogenic factor in extraintestinal infections including sepsis. We investigated the effects of coronary administration of hemolysin on cardiac function in isolated rat hearts perfused at constant flow. DESIGN: Prospective, experimental study. SETTING: Research laboratory at a university hospital. SUBJECTS: Isolated hearts from ...
Tajaddini Azita - - 2003
Most arterial mechanics studies have focused on excised non-coronary vessels, with few studies validating the application of ex-vivo results to in-vivo conditions. A method was developed for testing the mechanical properties of intact left anterior descending coronary arteries under a variety of conditions. Vascular deformation and pressure were simultaneously measured ...
Beckman Daniel J - - 2003
BACKGROUND: Hemodynamic instability remains a prominent concern for surgeons performing coronary surgery without cardiopulmonary bypass. The purpose of this study was to further elucidate the mechanism of hemodynamic instability by comparing vacuum stabilization to mechanical stabilization. METHODS: Four 60-kg swine were placed under general anesthesia. A median sternotomy incision was ...
Pohl Tilmann - - 2003
In 50 patients undergoing percutaneous transluminal coronary angioplasty because of chronic angina pectoris, a collateral flow index (CFI) was determined at the start and the end of two 1-min coronary occlusions, randomly accompanied by a resting state or a 3-min dynamic handgrip exercise (DHE). CFI expressing collateral flow relative to ...
Jung F - - 2003
It was tested whether a bolus injection of 10 ml radiographic contrast medium (iopromide vs. iohexol), compared to a 10 ml NaCl bolus and administered into the left anterior descending artery (LAD) of farm pigs, influenced the tissue pO2 in the territory of this artery. The radiographic contrast media and ...
Shimada Yasuyuki - - 2002
The circulation in the left and right coronary beds in pressure overload-induced left ventricular (LV) hypertrophy was studied in Wistar male rats (n=6/group) that were subjected to abdominal aortic constriction or to sham-operation. From 3 to 6 weeks after surgery, the animals with aortic constriction received vehicle or 0.01, 0.1, ...
Okuno Junko - - 2002
Blood pressure (BP) is poorly controlled in many countries. Poor compliance was suggested as the main cause for poor BP control. The purpose of this study was to examine the association between compliance and the control of both casual blood pressure (BP) and 24-hr ambulatory BP in a Japanese elderly ...
Galderisi Maurizio - - 2002
The aim of this study was to assess the relation between coronary blood flow and left ventricular (LV) myocardial diastolic dysfunction in arterial hypertension. The study population included 30 hypertensive patients who were free of coronary artery disease and pharmacologic therapies. They underwent standard Doppler echocardiography and color tissue Doppler ...
Degenhardt Heike - - 2002
10.1152/ajpheart.00925. 2001.-Parathyroid hormone-related peptide (PTHrP) is expressed throughout the cardiovascular system and is able to dilate vessels. This study investigated whether mechanical forces generated by changes in regional perfusion influence PTHrP release from the coronary vascular bed. Experiments were performed in vitro on saline-perfused rat hearts or isolated coronary endothelial ...
Siebes Maria - - 2002
Pressure-based fractional flow reserve (FFR) is used clinically to evaluate the functional severity of a coronary stenosis, by predicting relative maximal coronary flow (Q(s)/Q(n)). It is considered to be independent of hemodynamic conditions, which seems unlikely because stenosis resistance is flow dependent. Using a resistive model of an epicardial stenosis ...
de Ceuninck Michel - - 2002
Although measurements of the fractional flow reserve (FFR) provide accurate information on functional stenosis severity in many conditions, it remains unknown whether the extent of the vascular territory distal to the target lesion influences FFR calculations. Across a total of 16 selected coronary lesions intracoronary pressure during maximal hyperaemia was ...
Michaels Andrew D - - 2002
BACKGROUND: Enhanced external counterpulsation (EECP) is a noninvasive, pneumatic technique that provides beneficial effects for patients with chronic, symptomatic angina pectoris. However, the physiological effects of EECP have not been studied directly. We examined intracoronary and left ventricular hemodynamics in the cardiac catheterization laboratory during EECP. METHODS AND RESULTS: Ten ...
Misawa Katsushi - - 2002
We studied twelve patients with hypertensive left ventricular hypertrophy (LVH), 10 patients with hypertrophic cardiomyopathy (HCM) and 10 control subjects to examine the differences in coronary blood flow (CBF) dynamics between patients with hypertensive LVH and those with HCM. All subjects had normal coronary arteriograms. Measurements of CBF using Doppler ...
Galderisi Maurizio - - 2002
BACKGROUND: The reduction of coronary flow reserve (CFR) found in arterial hypertension may be due to changes in afterload, left ventricular (LV) structure, and metabolic factors. Also, insulin-like growth factor-1 (IGF-1) may be associated with the magnitude of CFR in relation to its modulating action on cardiac and endothelial function. ...
Ueda Hiroyasu - - 2002
BACKGROUND: Although it was reported that the pulsatility of ascending aortic pressure is closely related to restenosis after percutaneous transluminal coronary angioplasty (PTCA), it is not known whether the reflection period of ascending aortic pressure can predict restenosis after PTCA. The purpose of this study was to evaluate whether reflection ...
Sesma J - - 2002
This study was performed to compare the effectiveness of external thoracic compressions with and without intra-aortic occlusion balloon with capnography and coronary and cerebral perfusion pressure (CPP) in the normothermic and traumatic-less cardiopulmonary arrest provoked by a ventricular fibrillation in pigs. This was an experimental study (cross-over study) in 14 ...
Philippe François - - 2002
BACKGROUND: Pulse pressure and aortic stiffness are both predictors of coronary artery disease. Whether these parameters are directly related to coronary structural alterations has never been studied. METHODS: From September 1999 to September 2000, the following data were collected from 99 eligible patients: invasive intra-aortic systolic and diastolic blood pressures ...
Meuwissen Martijn - - 2002
Both coronary blood flow velocity reserve (CFVR) and myocardial fractional flow reserve (FFR) are used to evaluate the hemodynamic severity of coronary lesions. However, discordant results between CFVR and FFR have been observed in 25% to 30% of intermediate coronary lesions. An index of stenosis resistance based on a combination ...
Szabo Gabor - - 2002
BACKGROUND: To characterize the impact of brain death (BD) on endothelial dysfunction after cardiac transplantation we investigated coronary circulation and vasomotor function in a canine model. METHODS: Left ventricular pressure-volume data (conductance catheter) and coronary blood flow (CBF) were monitored continuously. Endothelium-dependent vasodilatation after acetylcholine and endothelium-independent vasodilation after sodium ...
Hoffman William E - - 2002
OBJECTIVE: To compare sodium nitroprusside (SNP)-induced hypotension with desflurane-induced hypotension for the effects on myocardial blood flow and tissue oxygenation in dogs. DESIGN: Prospective, randomized, crossover, nonblinded. SETTING: University teaching hospital. PARTICIPANTS: Male nonpurpose-bred hounds (n = 8). INTERVENTIONS: Dogs were anesthetized with 8% desflurane. Catheters were inserted into the ...
Marques Koen M J - - 2002
OBJECTIVES: We assessed the feasibility and reproducibility of the instantaneous diastolic coronary flow velocity-pressure gradient relation to characterize different degrees of coronary stenoses. BACKGROUND: Assessment of the hemodynamic significance of coronary stenoses can be difficult. Using sensor-tipped guidewires, various physiologic indexes can be determined in the catheterization laboratory. Each of ...
Yeatman Mark - - 2002
BACKGROUND: This study investigated the hemodynamic changes in patients undergoing multiple vessel beating heart coronary revascularization in the presence or absence of an intracoronary shunt. METHODS: Forty patients were randomized to off-pump with a shunt (n = 20) or with the proximal coronary artery occluded by a soft snare (n ...
Li Xiaoying - - 2002
OBJECTIVE: To observe the characteristics of coronary microvascular lesions (CML) in the autopsied elderly cases with hypertensive left ventricular hypertrophy (LVH) and the difference of CML among the groups of essential hypertension (EHT), coronary heart disease (CHD) and diabetes (NIDDM) also with LVH. METHODS: A retrospective study was performed in ...
Khosla P - - 2002
The effects of aqueous leaf extract of Azadirachta indica were evaluated on isolated prefused frog and rabbit heart. Dose dependent negative inotropic and chronotropic effects were observed in both the heart preparation. An increase in coronary blood flow in isolated rabbit heart was observed. The effects were not blocked by ...
Brosh David - - 2002
OBJECTIVES: We sought to test the hypothesis that the pulse transmission coefficient (PTC) can serve as a nonhyperemic physiologic marker for the severity of coronary artery stenosis in humans. BACKGROUND: Coronary lesions may impair the transmission of pressure waves across a stenosis, potentially acting as a low-pass filter. The PTC ...
Ni┼čanci Yilmaz - - 2002
Although the pressure gradient between the normal and stenotic vascular regions is known to be the most important factor for collateral vessel development, factors which are responsible for variations among patients with ischemic heart disease are not well known. Likewise, it is still not clear whether diabetes mellitus (DM) has ...
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