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PubMed2001

The estimation of cardiac function from the rotary blood pump.

The rotary blood pump is implanted as a bridge to cardiac transplantation. Mechanical, histological, and biochemical improvements have been described in patients after implantation of left ventricular assist devices (LVADs). Thus, the rotary blood pump might be used as a bridge to recovery of myocardial function. However, unlike a pulsatile pump, the rotary blood pump cannot be stopped to estimate cardiac function: if the rotary blood pump stops, backflow will occur. In this study, a new method that can estimate cardiac function without pump stop was examined. Six pigs were the subjects of this acute study. The pump was implanted as an LVAD: the inlet cannula was inserted into the left ventricle, and the outlet cannula was inserted into the ascending aorta. The motor speed was regulated at a pump flow rate of 0 L/min at diastolic phase. Then, the relationship between the dp/dt of left ventricular pressure and external stroke work of actuator was examined. This method was studied at normal, hyperdynamic, and heart-failure conditions. There was a high positive correlation between the dp/dt of left ventricular pressure and external stroke work of actuator. This method is useful and simple to estimate cardiac function without pump stop.

Animals↗
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↗
PubMed2002

Modifications of cardiac function in cirrhotic patients treated with transjugular intrahepatic portosystemic shunt (TIPS).

OBJECTIVES: The implantation of a transjugular intrahepatic portosystemic shunt (TIPS) has been shown to exacerbate the hyperdynamic circulation and might induce a significant cardiac overload. We investigated cardiac function before and 1, 3, 6, and 12 months after the TIPS procedure in cirrhotic patients. METHODS: Eleven patients with nonalcoholic cirrhosis were evaluated. Cardiovascular parameters were assessed by two-dimensional Doppler echocardiography. RESULTS: After TIPS, the left ventricular diastolic diameter increased from 26.5 +/- 1.8 mm (basal) to 30.0 +/- 2.8 mm (6 months) (p < 0.05), whereas the ejection fraction showed a slight increase (basal, 64.5 +/- 3.3; 6 months, 68.1 +/- 3.2). The left ventricular pre-ejection period and the isovolumetric relaxation time decreased transiently at 1 month (p < 0.05). An increased velocity in all of the components of pulmonary venous flow (systolic, diastolic, and atrial) documented the accelerated fluxes induced by the procedure. The estimated pulmonary systolic arterial pressure also increased at 1 month (29.5 +/- 1.4 vs 44.1 +/- 1.4 mm Hg, p < 0.05). All of these modifications reverted after 6 months. CONCLUSIONS: Our study demonstrates that nonalcoholic cirrhotic patients, without cardiovascular pathologies, show transient modifications in cardiac dimension and function for 3-6 months after TIPS caused by the increased volume load shunted to the heart.

Aged↗
PubMed2001

Effects of avertin versus xylazine-ketamine anesthesia on cardiac function in normal mice.

Anesthetic regimens commonly administered during studies that assess cardiac structure and function in mice are xylazine-ketamine (XK) and avertin (AV). While it is known that XK anesthesia produces more bradycardia in the mouse, the effects of XK and AV on cardiac function have not been compared. We anesthetized normal adult male Swiss Webster mice with XK or AV. Transthoracic echocardiography and closed-chest cardiac catheterization were performed to assess heart rate (HR), left ventricular (LV) dimensions at end diastole and end systole (LVDd and LVDs, respectively), fractional shortening (FS), LV end-diastolic pressure (LVEDP), the time constant of isovolumic relaxation (tau), and the first derivatives of LV pressure rise and fall (dP/dt(max) and dP/dt(min), respectively). During echocardiography, HR was lower in XK than AV mice (250 +/- 14 beats/min in XK vs. 453 +/- 24 beats/min in AV, P < 0.05). Preload was increased in XK mice (LVDd: 4.1 +/- 0.08 mm in XK vs. 3.8 +/- 0.09 mm in AV, P < 0.05). FS, a load-dependent index of systolic function, was increased in XK mice (45 +/- 1.2% in XK vs. 40 +/- 0.8% in AV, P < 0.05). At LV catheterization, the difference in HR with AV (453 +/- 24 beats/min) and XK (342 +/- 30 beats/min, P < 0.05) anesthesia was more variable, and no significant differences in systolic or diastolic function were seen in the group as a whole. However, in XK mice with HR <300 beats/min, LVEDP was increased (28 +/- 5 vs. 6.2 +/- 2 mmHg in mice with HR >300 beats/min, P < 0.05), whereas systolic (LV dP/dt(max): 4,402 +/- 798 vs. 8,250 +/- 415 mmHg/s in mice with HR >300 beats/min, P < 0.05) and diastolic (tau: 23 +/- 2 vs. 14 +/- 1 ms in mice with HR >300 beats/min, P < 0.05) function were impaired. Compared with AV, XK produces profound bradycardia with effects on loading conditions and ventricular function. The disparate findings at echocardiography and LV catheterization underscore the importance of comprehensive assessment of LV function in the mouse.

Adrenergic alpha-Agonists↗
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↗
PubMed2001

A cardiac myocyte vascular endothelial growth factor paracrine pathway is required to maintain cardiac function.

The role of the cardiac myocyte as a mediator of paracrine signaling in the heart has remained unclear. To address this issue, we generated mice with cardiac myocyte-specific deletion of the vascular endothelial growth factor gene, thereby producing a cardiomyocyte-specific knockout of a secreted factor. The hearts of these mice had fewer coronary microvessels, thinned ventricular walls, depressed basal contractile function, induction of hypoxia-responsive genes involved in energy metabolism, and an abnormal response to beta-adrenergic stimulation. These findings establish the critical importance of cardiac myocyte-derived vascular endothelial growth factor in cardiac morphogenesis and determination of heart function. Further, they establish an adult murine model of hypovascular nonnecrotic cardiac contractile dysfunction.

Animals↗
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↗
PubMed1998

Cardiac function in patients with treated hypertension during aortic aneurysm repair.

OBJECTIVES: To investigate the impact of arterial hypertension on cardiac function during aortic cross-clamping and declamping. DESIGN: Prospective study. SETTING: University hospital. PARTICIPANTS: Twenty treated hypertensive males with slight left ventricular hypertrophy and 10 normotensive controls undergoing elective repair of an abdominal aortic aneurysm. INTERVENTIONS: Using transesophageal echocardiography, the mitral inflow profile was evaluated during aortic cross-clamping and declamping. MEASUREMENTS AND MAIN RESULTS: During the clamping period, the ratio of peak atrial to peak early filling velocity (PA/PE) was significantly higher in the hypertensive patients. One minute after aortic cross-clamping, mean arterial pressure (MAP) and pulmonary artery occlusion pressure significantly increased in the hypertensive patients, whereas they did not change in the normotensive group. Cardiac index and heart rate significantly decreased after cross-clamping, and increased after clamp release in both groups. PA/PE significantly dropped in both groups after aortic declamping, and returned to baseline values thereafter. MAP also decreased significantly in both groups after clamp release, but the fall of MAP tended to be more pronounced in the hypertensive patients. CONCLUSIONS: In the treated hypertensive patients, more pronounced hemodynamic and echocardiographic responses to aortic cross-clamping probably mirror the altered diastolic left ventricular function in these patients. With respect to intraoperative management, however, the treated hypertensive patients did not react grossly differently from the normotensive controls.

Aged↗
PubMedDate not supplied

Assessment of cardiac function by echocardiography in Paget's disease of bone.

OBJECTIVE: To identify the mechanisms which influence the development of cardiac insufficiency in Paget's disease of bone (PD). METHODS: In this hospital-based case-control study 23 consecutive, recently diagnosed and untreated PD patients were compared against 23 controls frequency-matched by sex, age and body index. All subjects underwent non-invasive assessment of cardiac function by two-dimensional Doppler echocardiography. Calcium, phosphate, and creatinine were determined in the serum and urine, along with alkaline phosphatase and hydroxyproline excretion, two biochemical parameters of PD activity. RESULTS: Peripheral vascular resistance proved lower (1604.9 +/- 390.1 vs 1801.2 +/- 421.0) and the stroke volume higher in PD patients (67.2 +/- 14.4 vs 56.0 +/- 8.6; p = 0.07) compared with controls. These differences were greater (1504.7 +/- 289.9 and 71.0 +/- 6.2) and attained statistical significance (p = 0.008) when the subgroup with more extensive skeletal disease only was considered. A moderate correlation was observed between hydroxyproline excretion and the E/A ratio (r = 0.45; p = 0.03), peripheral vascular resistance (r = -0.42; p = 0.04), and diastolic arterial pressure (r = -0.42; p = 0.04). The final model obtained via multivariate analysis identified both urinary hydroxyproline and age as predictive variables linked to peripheral vascular resistance. CONCLUSION: In the early phases of PD there is a trend towards a reduction in peripheral vascular resistance. If this persists, it may lead progressively to increased cardiac output, which is mainly influenced by the degree of turnover impairment and the age of the individual.

Aged↗
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↗
PubMed2003

Glycation end-product cross-link breaker reduces collagen and improves cardiac function in aging diabetic heart.

Aging and diabetes mellitus (DM) both affect the structure and function of the myocardium, resulting in increased collagen in the heart and reduced cardiac function. As part of this process, hyperglycemia is a stimulus for the production of advanced glycation end products (AGEs), which covalently modify proteins and impair cell function. The goals of this study were first to examine the combined effects of aging and DM on hemodynamics and collagen types in the myocardium in 12 dogs, 9-12 yr old, and second to examine the effects of the AGE cross-link breaker phenyl-4,5-dimethylthazolium chloride (ALT-711) on myocardial collagen protein content, aortic stiffness, and left ventricular (LV) function in the aged diabetic heart. The alloxan model of DM was utilized to study the effects of DM on the aging heart. DM induced in the aging heart decreased LV systolic function (LV ejection fraction fell by 25%), increased aortic stiffness, and increased collagen type I and type III protein content. ALT-711 restored LV ejection fraction, reduced aortic stiffness and LV mass with no reduction in blood glucose level (199 +/- 17 mg/dl), and reversed the upregulation of collagen type I and type III. Myocardial LV collagen solubility (%) increased significantly after treatment with ALT-711. These data suggest that an AGE cross-link breaker may have a therapeutic role in aged patients with DM.

Aging↗
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↗