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PubMed1999

Influence of arterial pulse and reflective waves on systolic blood pressure and cardiac function.

Hypertension is a cardiovascular risk factor classically attributed to a reduction in the calibre and/or number of small arteries and arterioles resulting in increased peripheral vascular resistance. The definition of blood pressure as a product of total peripheral resistance (TPR) and cardiac output, however, does not take into account the fluctuation of blood pressure and flow during the cardiac cycle, with systolic and diastolic blood pressure representing the extremes of pulse pressure fluctuations. Diastolic blood pressure is closer to mean blood pressure (and therefore to TPR) than systolic blood pressure, and as such has been used as a marker for the diagnosis of hypertension. However, this approach has no rational basis and was challenged by the Framingham Heart Study which demonstrated that systolic rather than diastolic blood pressure is a better risk marker for stroke and coronary artery disease in subjects aged 45 years and older. This view has subsequently been confirmed by several epidemiological and interventional studies. Systolic blood pressure is closely associated with pulse pressure and is determined by the pattern of left ventricular ejection, arterial stiffness and timing of arterial wave reflections, i.e. the geometrical and viscoelastic properties of large conduit arteries. In humans, with ageing and hypertension, the arteries stiffen as a result of progressive degeneration of the arterial media, increased collagen and calcium content, and dilation and hypertrophy of large arteries and the aorta. Thus, the increase in systolic blood pressure (as a result of arterial damage) increases the fatigue of arterial walls and accelerates arterial damage, producing a self-perpetuating cycle.

Blood Pressure↗
PubMed1994

Ultrasonic tissue characterization: integrated backscatter imaging for detecting myocardial structural properties and on-line quantitation of cardiac function.

Quantitative myocardial tissue characterization is being developed as an adjunct to conventional echocardiography to delineate the physical state of myocardium under diverse pathophysiological states. Real-time quantitative integrated backscatter imaging has made possible clinical investigations carried out in the United States, Europe, and Japan in patients with ischemic heart disease, hypertrophic cardiomyopathy, and cardiac allograft rejection, among others. A modification of the imaging processing used for characterization of tissue facilitates automatic detection of endocardial blood interfaces and on-line quantification of ventricular size and function, which has been recently introduced in clinical practice. Further progress and developments in quantitative ultrasonic imaging will place in perspective the clinical use of tissue characterization based on myocardial backscatter.

Animals↗
PubMed1998

Three-dimensional analysis of regional cardiac function: a model of rabbit ventricular anatomy.

The three-dimensional geometry and anisotropic properties of the heart give rise to nonhomogeneous distributions of stress, strain, electrical activation and repolarization. In this article we review the ventricular geometry and myofiber architecture of the heart, and the experimental and modeling studies of three-dimensional cardiac mechanics and electrophysiology. The development of a three-dimensional finite element model of the rabbit ventricular geometry and fiber architecture is described in detail. Finally, we review the experimental results, from the level of the cell to the intact organ, which motivate the development of coupled three-dimensional models of cardiac electromechanics and mechanoelectric feedback.

Animals↗
PubMed1995

Enalaprilat controls postoperative hypertension while maintaining cardiac function and systemic oxygenation after neurosurgery.

OBJECTIVE: The efficacy of intravenous enalaprilat in lowering postoperative hypertension. DESIGN: Prospective, randomized, controlled, single blind trial. SETTING: Surgical ICT in a university hospital (tertiary care center). PATIENTS: 18 neurosurgical patients subjected to the extirpation of a supratentorial intracerebral tumour were studied after detection of postoperative hypertension. This was defined as a constant elevation of systolic arterial pressure over 160 mmHg or diastolic arterial pressure over 95 mmHg. INTERVENTIONS: Enalaprilat 0.015 mg kg-1 was injected within 5 min to 9 patients. MEASUREMENTS AND RESULTS: Central haemodynamics and systemic oxygenation were assessed at baseline before enalaprilat injection, and repeatedly during four hours after the injection. The statistical analysis was performed with analysis of variance for repeated measurements. As compared to control patients, the blood pressure lowering effect of enalaprilat became evident within 15 min and lasted for over four hours (p = 0.008). It was mainly due to the reduced systemic vascular resistance. Enalaprilat also induced a small decline in myocardial perfusion pressure. Cardiac performance, preload, heart rate and systemic oxygenation were not affected by enalaprilat. CONCLUSIONS: We found intravenous enalaprilat effective and safe in lowering postoperative hypertension following neurosurgery as assessed by it's effects on central haemodynamics and systemic oxygenation.

Adult↗
PubMed2006

[Effect of perindopril on indices of cardiac function and quality of life in patients with arterial hypertension in regard to age].

At present in the treatment of arterial hypertension the role of angiotensine converting enzyme inhibitors is significant. From this group the most special attention was attracted to peridopril-esbumin. High efficiency of this preparation has been corroborated by numerous controlled, multicentral investigations. Study of the effect of dosage and peculiarities of peridopril appears to be the most important taking into account age factor that has been insufficiently studied. The goal of our investigation was to study effect of 4 mg and 8 mg of peridopril on functional indices of the heart of patients with hypertonic disease and their psychoemotional sphere in the aspect of age. Total of 78 patients with hypertension and without clinical manifestations of cardiac insufficiency, diabetes mellitus and having had myocardial infarction were examined. According to the age patients were divided into two groups: <65 and >65. The investigations lasted for 12 months. Besides ECG investigations, patients were subjected to echoscopic and doplerographic investigations. For the estimation of life quality a questionnaire of evaluation of general health state (SF-36 Health Status Surveu) containing 11 questions was used. It was shown that peridopril has the different action among patients of different age groups. In older patients (>65 years) it increases indices of physical activity, while in younger patients it has a beneficial effect on the emotional parameters.

Age Factors↗
PubMed1983

A noninvasive radiographic technique for evaluation of exercise-induced changes in cardiac function.

An electrocardiographic-triggered radiographic technique for obtaining a single image of the heart at both end-systole and end-diastole was used in conjunction with upright bicycle exercise to detect stress-induced changes in 1) systolic and diastolic cardiac transverse diameter, and 2) regional motion of the free left ventricular wall. Twenty-one patients were studied; 10 had normal coronary arteries and 11 had significant coronary artery disease. Twenty patients (10 with normal coronary arteries and 10 with coronary artery disease) also had multigated radionuclide blood pool scans at rest and with exercise. All patients without coronary disease showed a decrease in systolic cardiac transverse diameter with exercise and a slight increase in amplitude of motion of the left ventricular free wall. Eight (73%) of the 11 patients with coronary artery disease showed an increase in systolic transverse cardiac diameter with exercise (p less than 0.001), and 5 developed either new regional left ventricular asynergy or deterioration of segments with rest asynergy. Eight of the 10 patients with coronary artery disease who had rest and exercise radionuclide scans had an abnormal ejection fraction response to exercise. However, only 4 of the 10 control patients who had multigated scans had a normal ejection fraction response, although all showed normal regional wall motion with exercise. This new approach is inexpensive and easily performed. These preliminary data suggest that it may be a useful adjunct to cardiac stress testing and is worthy of further study.

Adult↗
PubMed1991

[Evaluation of myocardial blood flow and cardiac functional change in acromegaly].

We studied 201Tl myocardial scintigraphy and 99mTc-HSA gated blood pool scan to evaluate the influence of growth hormone on myocardial blood flow and hemodynamics in 16 patients with acromegalies. Contraction properties were almost within normal limit, but cardiac output was in high output state, because left ventricular ejection fraction (LVEF), right ventricular ejection fraction (RVEF) and cardiac output were 47.8 +/- 17.1%, 37.3 +/- 14.9%, and 6.4 +/- 1.7 L/min, respectively. Otherwise, 201Tl myocardial images revealed 62.5% no redistributed hypoperfusion, 18.8% redistributed hypoperfusion, 56.3% myocardial hypertrophy and 25.0% left ventricular enlargement. These data suggested the high incidence of acromegalic cardiomyopathy due to primary or secondary growth hormone effect.

Acromegaly↗
PubMed1983

Comparison of effects of nifedipine and nitroglycerin on large and small coronary arteries and cardiac function in conscious dogs.

The effects of nifedipine, 20 micrograms/kg, iv, and nitroglycerin, 25 micrograms/kg, iv, were compared in conscious dogs, instrumented for instantaneous and continuous measurements of coronary arterial and left ventricular (LV) diameters, arterial and LV pressures, coronary blood flow, and cardiac output. The two drugs were administered to reduce arterial pressure initially by similar amounts, by approximately 30 mm Hg. The maximal increases in large coronary arterial dimensions occurred 2-4 minutes after the initial peak reductions in arterial pressure and increases in coronary blood flow. The maximal increase in large coronary arterial cross-sectional area with nifedipine (28 +/- 2.9%) and nitroglycerin (33 +/- 5.3%) were similar. At this time, nifedipine increased coronary blood flow (114 +/- 20%) and reduced late diastolic coronary vascular resistance (-61 +/- 3.1%), whereas nitroglycerin reduced coronary blood flow (-14 +/- 1.7%) and increased late diastolic coronary vascular resistance (15 +/- 6.6%). During the time of peak large coronary arterial dilation, nifedipine reduced mean arterial pressure (-13 +/- 2.1%) and total peripheral resistance (-30 +/- 2.6%), whereas, with nitroglycerin, arterial pressure was not different from control and total peripheral resistance was significantly increased (13 +/- 1.8%). At this time, LV end-diastolic diameter was reduced with nitroglycerin (-5.6 +/- 0.4%) but unaffected by nifedipine. Thus, in the conscious dog, nitroglycerin and nifedipine induced similar effects on large coronary arteries but differing effects on resistance coronary and peripheral vessels as well as preload. Nifedipine, in contrast to nitroglycerin, induced sustained vasodilation of both coronary resistance vessels and peripheral arterioles, whereas nitroglycerin, but not nifedipine, reduced preload.

Animals↗
PubMed1995

Effects of NKH477, a water-soluble forskolin derivative, on cardiac function in rats with chronic heart failure after myocardial infarction.

Our study was designed to determine whether NKH477, a novel, potent and water-soluble forskolin derivative, may exert a positive inotropic effect in rats with chronic heart failure (CHF) after myocardial infarction. Cardiac output and stroke volume indices were decreased and systemic vascular resistance was increased 12 wk after left coronary artery ligation, suggesting that CHF has developed at this time. Dobutamine (4 micrograms/kg i.v.) increased the cardiac output and stroke volume indices in sham-operated rats (22.7 +/- 1.9 and 15.1 +/- 2.0% increase, respectively), whereas such increases were attenuated in rats 12 wk after the induction of myocardial infarction (cardiac output index: 4.0 +/- 1.4% increase and stroke volume index: 2.2 +/- 1.8% increase, respectively). In contrast to beta-adrenoceptor agonist, NKH477 (3, 10 and 30 micrograms/kg i.v.) increased cardiac output and stroke volume indices in the rats with CHF. The beta-adrenergic receptor density, measured by [3H] CGP-12177 binding assay, was reduced in homogenates of the failing heart. These results suggest that the decrease in cardiac beta-adrenergic receptor density may account, in part, for the reduction in the responsiveness to beta-adrenoceptor agonists. The primary defects in the signal transduction from beta-adrenergic receptor to adenylate cyclase, such as the receptor down-regulation and the failure in signaling from adenylate cyclase, may be present in the CHF heart. It may be possible to reverse the cardiac dysfunction associated with CHF with NKH477.

Animals↗
PubMed1995

In vivo effects of a novel thromboxane A2/prostaglandin H2 (TXA2/PGH2) partial agonist, (+)5(Z)-7-[3-endo-phenylsulfonylamino[2.2.1]- bicyclohept-2-exo-yl]-heptenoic acid [(+)-S-145], on vascular, platelet and cardiac function.

A novel thromboxane A2/prostaglandin H2 (TXA2/PGH2) receptor ligand, (+)5(Z)-7-[3-endo-phenylsulfonylamino[2.2.1]-bicyclohept-2-e xo- yl]-heptenoic acid [(+)-S-145], was evaluated in guinea pigs to assess the in vivo pharmacodynamic profile of this compound at vascular, cardiac and platelet TXA2/PGH2 receptors. Comparison was made to the TXA2/PGH2 receptor antagonist SQ29548. Upon i.v. injection, (+)-S-145, but not SQ29548, elicited transient (approximately 1 min) increases in mean arterial blood pressure (ED50 +/- 95% confidence limit = 6.1 + 4.0, -2.2 micrograms/kg). The potency of i.v. (+)-S-145 (ID50 = 6.3 + 2.3, -2.3 micrograms/kg) against the pressor response to subsequent i.v. TXA2/PGH2 mimetic, U44069, was 9.5-fold greater than that of SQ29548 (ID50 = 59.1 + 52.9, - 52.9 micrograms/kg). Intravenous (+)-S-145 inhibited U44069-induced decreases in circulating platelet count (ID50 = 4.2 + 4.1, - 2.0 micrograms/kg). In thoracotomized guinea pigs, i.v. (+)-S-145 (31.6 micrograms/kg) and increasing i.v. doses of U44069 increased mean arterial blood pressure, total peripheral resistance, left ventricular end-diastolic pressure and left ventricular peak positive dP/dt (LV + dP/dt) and depressed cardiac output (P < .05). Pretreatment with i.v. (+)-S-145 (31.6 micrograms/kg) abolished these U44069-induced effects. In thoracotomized guinea pigs in which left ventricular end-diastolic pressure and HR were held constant, U44069 again increased LV + dP/dt (P < .05), but (+)-S-145 decreased LV + dP/dt (P < .05), which indicates the lack of an (+)-S-145 direct inotropic effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Cardiac function and central haemodynamics in severe chronic obstructive lung disease. Acute and long-term effects of felodipine.

Eleven patients, with advanced chronic obstructive lung disease (COLD), received an infusion of the calcium antagonist felodipine at a rate of 0.9 mg/h. Pulmonary and systemic vascular resistances (PVR and SVR) at rest were reduced by 18% (p less than 0.05) and 33% (p less than 0.001), respectively. Cardiac output increased by 33%. The right ventricular and left ventricular ejection fractions (RVEF and LVEF), measured by equilibrium gated radionuclide ventriculography, increased by 32% (p less than 0.01) and 25% (p less than 0.01), respectively. During exercise both PVR and SVR fell by a mean of 30% (p less than 0.01). RVEF and LVEF both increased by about 14% (p less than 0.05 and p less than 0.01). After three months of oral felodipine treatment, a dose-related decrease in PVR was noted at rest (r = -0.83) compared with pretreatment values. There was an increase in RVEF which correlated to a reduction in PVR (r = -0.76). Three patients discontinued the trial due to side effects. It is concluded that the reduction of PVR induced by felodipine is accompanied by an improvement in right heart function as measured by ejection fraction measurements.

Aged↗