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At least 289 records · Page 16Linked to original sources
PubMed1991

Beneficial effects of yohimbine on posthypoxic recovery of cardiac function and myocardial metabolism in isolated perfused rabbit hearts.

The present study was undertaken to elucidate the possible actions of yohimbine on cardiac function and metabolism in the hypoxic and subsequently reoxygenated myocardium. For this purpose, rabbit hearts were perfused for 20 min under hypoxic conditions, followed by 45 min reoxygenated perfusion, and their functional and metabolic alterations with and without yohimbine treatment were examined. Hypoxia induced cessation of cardiac contractile force, rise in resting tension and depletion of tissue high-energy phosphates, which were poorly recovered by subsequent reoxygenation. Hypoxia also induced release of creatine kinase and ATP metabolites from perfused hearts and increases in tissue calcium and sodium contents, which were further enhanced upon subsequent reoxygenation. When hypoxic hearts were treated with 3 to 30 microM yohimbine, several beneficial effects were observed in a concentration-dependent manner. This included enhancement of posthypoxic recovery of contractile function and suppression of the hypoxia- and reoxygenation-induced rise in resting tension. Hypoxia/reoxygenation-induced release of ATP metabolites was inhibited and restoration of myocardial high-energy phosphates enhanced. Inhibition of reoxygenation-induced rise in tissue calcium and sodium and creatine kinase release were also noted. The findings suggest that suppression of transmembrane flux of ions, substrates and enzymes during hypoxia/reoxygenation plays a role in the posthypoxic functional and metabolic recovery. Yohimbine (3-30 microM) significantly depressed the maximal stimulus frequency the left atria could follow. These results suggest a close relationship between depression in the maximal driving frequency of atria and enhancement of the posthypoxic contractile and metabolic recovery of perfused hearts.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1995

Exacerbated tamponade: deterioration of cardiac function by lowering excessive arterial pressure in hypertensive cardiac tamponade.

Patients with cardiac tamponade usually have significant hypotension; hypertension is rare. Before administering any medication during tamponade one must consider the complex physiology and compensatory mechanisms of cardiac compression [1]. We observed both an accentuation of pulsus paradoxus and retrospectively recognized fluctuations of left-ventricular function after progressively rising arterial blood pressure had been lowered.

Antihypertensive Agents↗
PubMed1992

Exercise training improves cardiac function after ischemia in the isolated, working rat heart.

The aim of this study was to determine whether exercise training produces a myocardium intrinsically more tolerant to ischemic-reperfusion injury. Male Fischer 344 rats were treadmill trained for 11-16 wk at one of the following intensities: LOW (20 m/min, 0% grade, 60 min/day), moderate (MOD; 30 m/min, 5% grade, 60 min/day) or intensive (INT; 10 bouts of alternating 2-min runs at 16 and 60 m/min, 5% grade). Cardiac function was evaluated both before and after 25 min of global, zero-flow ischemia in the isolated, working heart model. Compared to hearts from sedentary (SED) rats, postischemic cardiac output (CO) and work were significantly higher in all trained groups. Percent recovery of CO (relative to preischemia) was 36.0 +/- 7.1 in SED and 61.2 +/- 6.5, 68.1 +/- 9.3, and 73.2 +/- 5.0 in LOW, MOD, and INT, respectively. Postischemic increases in stroke volume with increased preload and cardiac work at high work load were significantly higher in INT compared with SED. Coronary flow during initial retrograde reperfusion was significantly enhanced with training and correlated with subsequent recovery of CO (R2 = 0.613). Furthermore, trained hearts had higher phosphocreatine (P less than 0.05) and ATP (P less than 0.01) contents after 45 min reperfusion. It is concluded that exercise training results in an intrinsic myocardial adaptation, allowing greater recovery of cardiac pump function after global ischemia in the isolated rat heart.

Adenosine Triphosphate↗
PubMed1979

Non-invasive assessment of cardiac function in meningitis.

Non-invasive registration of systolic time intervals (STI) and ECG were used in evaluating cardiac function in 12 patients with bacterial and 16 with viral meningitis. On admission, 14 (50%) of the patients had abnormal STI. The preejection period (PEP) was prolonged in 11 patients, while left ventricular ejection time (LVET) was prolonged in two and shortened in four. The PEP/LVET index was increased in eight patients. At discharge PEP was still prolonged in eight patients; seven of these were from the viral meningitis group. LVET increased significantly (p less than 0.02) from the first to the last registration. In the patients with abnormal PEP and PEP/LVET on admission, there was a significant fall (p less than 0.05 and p = 0.02, respectively) to discharge. There was no difference in STI between the patients with viral or bacterial meningitis. Eighteen (64%) of the patients had abnormal STI on one or more registration. ST-T changes in ECG and prolongation of the Q-T interval were found in three patients. Cardiac affection in meningitis seems to occur more often than can be shown by ECG.

Adolescent↗
PubMed1988

Gated radionuclide ventriculography in the evaluation of cardiac function in Duchenne's muscular dystrophy.

Left ventricular ejection fractions were determined in 38 patients with Duchenne's muscular dystrophy. No significant correlation between the severity of respiratory dysfunction or age and cardiac function was seen. We suggest that the cardiac status of each patient should be evaluated separately from his respiratory status, particularly when long-term assisted ventilation is being considered.

Adolescent↗
PubMed1979

Cardiac function and morphology with aging in the spontaneously hypertensive rat.

To determine the effects of a chronic pressure load on cardiac function and morphology, spontaneously hypertensive rats (SHR) and two normotensive strains of Wistar rats (WKY and NWR) were studied under ether anesthesia at 13, 25, 52, and 90 wk of age. Although resting cardiac index of the SHR was comparable to that of WKY and NWR at all ages, the peak cardiac output and peak stroke volume per gram of left ventricle determined during a rapid intravenous infusion of Tyrode solution was markedly reduced in the SHR only at 90 wk of age. Autonomic inhibition did not alter the peak stroke volume attained, but reduced peak cardiac output at all ages in each of the strains. Absolute left ventricular dimensions in the SHR increased out of proportion to body growth, consistent with concentric hypertrophy. As peak pumping ability markedly declined from 52 to 90 wk of age in the SHR, the free wall of the left ventricle greatly thickened whereas the septum remained unchanged. At this time the right ventricle also hypertrophied. This disproportionate thickening of the walls of the left ventricle and the hypertrophy of the right ventricle were reflected in measurements of their fiber diameters. These alterations in ventricular architecture may contribute to the decrease in pumping ability observed in long-standing hypertension.

Aging↗
PubMedDate not supplied

Cardiac function in healthy infants and children: Doppler echocardiographic evaluation.

To establish normal values for Doppler-derived parameters of cardiac function, pulsed-wave Doppler recordings from the ascending aorta were obtained in 80 healthy infants and children. Stroke and minute distance, peak velocity, mean acceleration, acceleration and ejection time intervals, and the acceleration/ejection time ratios were measured or calculated from the Doppler recordings. The relations between the Doppler parameters and heart rate, age, and body surface area were analyzed separately for the children below and above 6 months of age. The normal values for the two groups are given as the median and range and as the mean and standard deviations, respectively. For the older age group, strong negative correlations with heart rate were found for stroke distance and ejection time, suggesting that these parameters should be evaluated in relation to heart rate. Intraobserver and interobserver reproducibility were studied in 10 children. Good reproducibility was found for stroke and minute distance, peak velocity, and left ventricular ejection time. For measurements related to acceleration, the reproducibility was less good.

Adolescent↗
PubMed1985

Quantitation of cardiac function by cine-CT.

The recent introduction of a millisecond CT scanner specifically designed for cinematographic real-time imaging of the heart is a significant advance, and its introduction could parallel the impact that cineangiography had on cardiac diagnosis. A major advantage of CT is that central catheterization for angiographic purposes is avoided, as relatively small amounts of intravenous contrast medium provide excellent CT contrast enhancement of the blood pool and cardiac structures. In this article, the cine-CT scanner and the scanning techniques involved are described briefly, and the methods used to analyze CT data are discussed. The initial results are described, as is the potential of cine-CT for quantitating cardiac function.

Cardiac Output↗
PubMed1995

Early abnormalities of cardiac function in non-insulin-dependent diabetes mellitus and impaired glucose tolerance.

The aim of this study was to evaluate the role of diabetes and minor abnormalities of glucose homeostasis, such as impaired glucose tolerance, as determinants of cardiac function and structure in a working population. We studied a population-based sample of 64 telephone company employees (both sexes, mean age 58 years): 25 with normoglycemia, 15 with impaired glucose tolerance, and 24 with non-insulin-dependent diabetes mellitus (NIDDM) diagnosed by oral glucose tolerance test according to the recommendations of the World Health Organization. Subjects with myocardial ischemia were excluded. Left ventricular end-systolic dimension, indexed to body surface area, was greater in those with NIDDM (p < 0.05) and in those with impaired glucose tolerance (p < 0.05) with respect to normoglycemic persons. The ratio of the peak early diastolic velocity wave to the late diastolic wave was lower in those with NIDDM (p < 0.05) and in those with impaired glucose tolerance (p < 0.05) than in participants with normoglycemia. Body mass index and blood pressure were similar in the 3 groups. These results clearly indicate that early abnormalities of cardiac structure and function are observed not only in patients with NIDDM, but also in those with impaired glucose tolerance, independent of the confounding role of myocardial ischemia, body weight, and blood pressure.

Adult↗
PubMed1989

Measurement of hepatocellular function, cardiac output, effective blood volume, and oxygen saturation in rats.

The available techniques do not permit the measurement of hepatocellular function, cardiac output, effective blood volume, and oxygen saturation in small animals without the need of blood or tissue sampling. We present methodology that permits us to measure the above variables in the rat. Multiple doses of indocyanine green (ICG; 0.16-2.6 mg/kg) were given to pentobarbital-anesthetized rats, and [ICG] was continuously measured by an in vivo hemoreflectometer. Initial velocity of clearance (Vo) was determined from the [ICG] vs. time plot for each dose by nonlinear regression. The maximal velocity of clearance (Vmax; indicating hepatocellular function) was calculated. Vmax was 1) accurately determined using two, three, or four doses of ICG; 2) it was 1.09 +/- 0.16 mg.kg-1.min-1, not different from the Vo of the near-saturating dose of 25 mg/kg; and 3) it decreased after partial hepatectomy. Cardiac output was 41.89 +/- 1.46 ml.100 g-1.min-1, effective blood volume was 6.12 +/- 0.34 ml/100 g, and oxygen saturation was 92 +/- 2%. These methodologies may prove useful in the evaluation of hepatocellular dysfunction and hemodynamic parameters in the rat during and after various diseased states.

Animals↗
PubMed1991

[Modern techniques of assistance and mechanical replacement of cardiac function].

There has been intensive technological and clinical research for many years into the assistance and mechanical replacement of cardiac function. The simplest systems (extracorporeal circulation using centrifuge pumps, hemopump) and more complex systems (orthotopic or heterotopic pneumatic ventricles, electric ventricles) have been shown to be effective in a variety of situations which up to now could not be controlled by pharmacological methods. These situations are made amenable to improvement by the application of these techniques. They make it possible to await the recovery of autonomous function or, in its absence, transplantation. Experience over the past 30 years provides guidance for current research into the artificial heart.

Heart Diseases↗
PubMed1992

Influence of pregnancy on mean systemic filling pressure and the cardiac function curve in guinea pigs.

To assess the degree of circulatory fullness and to evaluate the influence of peripheral and cardiac factors in the regulation of cardiac output during pregnancy, the following studies were conducted using pentobarbital-anesthetized, open-chest nonpregnant and late term pregnant guinea pigs. Mean circulatory filling pressure was taken as the equilibrium pressure when the pulmonary artery was constricted. Total vascular compliance was assessed by +/- 5-mL changes in blood volume performed while this constriction was maintained. A separate group of guinea pigs was prepared with a pulmonary artery electromagnetic flow probe and right atrial catheter. Rapid infusion of saline was used to increase right atrial pressure while the cardiac output was determined. Pregnancy was characterized by the following changes relative to nonpregnant controls: 51Cr-labelled RBC blood volume increased from 55 +/- 3 to 67 +/- 3 mL/kg; mean circulatory filling pressure increased from 7.1 +/- 0.2 to 8.0 +/- 0.5 mmHg (1 mmHg = 133.322 Pa); right atrial pressure decreased from 3.4 +/- 0.2 to 2.1 +/- 0.3 mmHg; and cardiac output increased from 71.8 +/- 3.9 to 96.8 +/- 3.3 mL.min-1.kg-1. Total vascular compliance was not changed (2.1 +/- 0.1 mL.kg-1.mmHg-1) and most of the expanded blood volume was accommodated as unstressed volume. The cardiac function curve was shifted upwards in pregnant animals. The resistance to venous return, as determined from the slope of the venous return curves, was not changed. These data suggest that the circulation of the pregnant guinea pig is slightly overfilled.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

[Effects of NaHCO3 on cardiac function and metabolism during hypoxic metabolic acidosis--2: Rapid infusion of NaHCO3].

The effects of 1M sodium bicarbonate (NaHCO3) on cardiac function and myocardial metabolism during hypoxia were compared with those of 1M sodium chloride (NaCl) in anesthetized dogs. Metabolic acidosis was induced with inhalation of low fraction of oxygen (9%) for 2 hours. NaHCO3 (n = 9) or NaCl (n = 10) was infused intravenously in a half dose of 0.2 x body weight x base excess mEq in 30 seconds. This treatment was repeated five minutes later. In NaHCO3 group; with first infusion, both blood and intramyocardial pH increased. Left ventricular pressure (LVP) and maximum rate of rise of LVP (LV dP/dt max) were unchanged. Cardiac index (CI) tended to increase, while left ventricular end-diastolic pressure (LVEDP) and LVEDP/LVP increased significantly. In five dogs in which myocardial glucose uptake increased, LV dP/dt max increased. With the second infusion, inspite of the increase of blood and intramyocardial pH, LVP and LV dP/dt max decreased significantly compared with the preceding values. In NaCl group, with first infusion, blood and intramyocardial pH decreased. CI increased significantly, while LVP and LV dP/dt max tended to decrease, and LVEDP and LVEDP/LVP increased significantly. After the second infusion, myocardial contractility was depressed significantly. In both groups, blood lactate (LA) level increased significantly, especially with NaHCO3 infusion. LV dP/dt max correlated significantly with LA in NaCl group (r = -0.614, P < 0.001). However, in NaHCO3 group, LV dP/dt max did not correlate with LA. Blood glucose level (r = 0.612, P < 0.001) and myocardial glucose uptake (r = 0.718, P < 0.001) correlated significantly with LV dP/dt max in NaHCO3 group.(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis, Respiratory↗
PubMed1972

Changes during eating in oxygen consumption, cardiac function and body fluids of sheep.

1. A study was made of the changes taking place in O(2) consumption, cardiac function and the volume and composition of the body fluids of sheep while they consumed a meal of hay.2. During eating P(a, CO2) and P(v, CO2) both increased, pH decreased and free plasma [HCO(3) (-)] increased. Venous haematocrit increased sharply at the beginning of the meal, and declined slowly after feed was removed.3. Arterial P(O2) did not change significantly during eating. However P(v, O2) fell slightly but significantly. The O(2) saturation of venous blood fell due to the decline in pH. Estimated CO(2) in arterial blood increased as a consequence of increased haemoglobin content. The net effect was to increase arteriovenous difference in O(2) content from 4.4 ml./100 ml. before eating to 6.0 ml./100 ml. at the end of the meal.4. O(2) consumption increased about 60% during eating and fell rapidly thereafter. Heart rate followed a similar pattern. Cardiac output however increased only about 17%, from 6 to 7 l./min. Consequently stroke volume declined throughout the meal from 76 to 52 ml./beat.5. Plasma volume, estimated from measurements of T-1824, declined sharply by about 300 ml. at the beginning of the meal and recovered slowly after feed was removed. Blood volume declined less because of a rise in circulating erythrocytes.6. Extracellular fluid volume was estimated from measurements of thiocyanate and thiosulphate spaces. Thiocyanate space measurements were abandoned after thiocyanate was found to be concentrated in saliva. Considerable random variation occurred in measurements of changes in extracellular fluid from thiosulphate disappearance but the results did reveal a significant fall of 1000-1500 ml. in extracellular fluid volume during eating.7. The significance of these interrelated changes is discussed in relation to the maintenance of homoeostasis during eating in the sheep.

Animal Nutritional Physiological Phenomena↗
PubMed1995

[Cardiac function in isolated working rat heart with pressure overload hypertrophy: correlation with myocardial angiotensin II].

Using the isolated working rat heart model, we recorded cardiac function of the hypertrophied hearts induced by abdominal aortic banding and determined the myocardial angiotensin II level. Compared with the sham-operated control hearts, the maximal diastolic rate (-dp/dt) and coronary flow rate (per gram of left ventricular weight) were decreased, while the myocardial angiotensin II content was increased in the hypertrophied hearts. Correlation analysis revealed that both coronary flow rate (r = -0.8097, P < 0.001) and -dp/dt (r = -0.5463, P < 0.01) were negatively correlated to myocardial angiotensin II. We conclude that the activated cardiac renin-angiotensin system may be responsible for the decreased diastolic function and coronary reserve in the hypertrophied hearts.

Angiotensin II↗
PubMed1983

Cardiac function in adolescents and young adults with anorexia nervosa.

Twelve patients with anorexia nervosa (mean age 17.6 years) underwent noninvasive cardiac evaluation. All patients had normal sinus rhythm at rest, during exercise, and following 24-hr electrocardiographic monitoring. The chest roentgenograms demonstrated a small heart secondary to a loss of left ventricular mass. Three of four patients studied had left ventricular mass measurements less than 100 g (normal is 90-360 g). Most patients had an elevated heart rate response to exercise with a slightly blunted systolic and a normal diastolic blood pressure response. Eleven of the 12 patients had reduced overall maximal working capacity. All but one had normal left ventricular ejection fraction at rest. There was no evidence of arrhythmias at rest, during exercise, or with continuous electrocardiographic recording. Young patients with anorexia nervosa appeared to have essentially normal cardiac function with a reduction in left ventricular muscle mass.

Adolescent↗
PubMed1988

Cardiac function in open-chest dogs after left to right ventricular shunting and right coronary artery occlusion.

Patients with acquired ventricular septal defect (VSD) after myocardial infarction have a particularly bad prognosis if right ventricular function is severely impaired. The significance of an ischaemic right ventricular free wall on cardiac function during interventricular shunting was examined in open-chest dogs. An external interventricular shunt could be opened and closed at will, and by occlusion of the right coronary artery (RCA), a part of the right ventricular free wall was rendered ischaemic. Aortic flow decreased by 8 +/- 2% when the shunt was opened in the presence of a normal right ventricle, and by 16 +/- 2% (difference: P less than 0.05) in the presence of right ventricular ischaemia. Aortic flow fell by 19 +/- 3% when the RCA was occluded. Right ventricular dyskinesia was demonstrated after occlusion of RCA, by recording segment lengths in the right ventricular free wall. The dyskinesia was aggravated when the shunt was opened. The left ventricle exerted a 'negative' work on the ischaemic right ventricular free wall. Retention of blood in the right ventricle, with a subsequent decline in left ventricular filling and an almost unchanged interventricular shunting of blood, explain why aortic flow fell more when the shunt was opened in the presence of right ventricular ischaemia.

Animals↗