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At least 505 records · Page 28Linked to original sources
PubMed1997

Global cardiac function using fast breath-hold MRI: validation of new acquisition and analysis techniques.

Calculation of global cardiac function parameters has been validated using fast, segmented k-space, breath-hold, gradient-echo, magnetic resonance images. Images of phantoms, experimental animals, normal volunteers, and patients were acquired with a 1.5 T clinical scanner. Humans were imaged using two phased-array surface coils in multicoil mode. Myocardial contours were extracted using a new interactive, semi-automated method based on the active contour model method. Images were acquired in the short-axis orientation, and, using a new imaging and analysis strategy, in rotating plane long-axis orientations, to provide better definition of the valve planes and the apex, and also to reduce the number of slices (compared with the short-axis method) required to sample the whole heart. Validation was accomplished through calculation of the volumes of phantoms and left and right ventricular masses of animal hearts. Functional parameters from MRI were compared with those from echocardiograms and radionuclide angiograms in normal volunteers and patients, respectively.

Adult↗
PubMed1989

Effects of terbutaline sulfate on fetal cardiac function.

An isolated heart preparation was used to study the effects of terbutaline sulfate (Brethine) on fetal cardiac function. Pregnant guinea pigs received daily subcutaneous injections of terbutaline for 10 day, whereas a control group received placebo injections. Fetal guinea pig hearts were evaluated for cariodynamic and pathologic differences. Fetuses exposed to terbutaline demonstrated a higher mean heart rate (p less than 0.01), a higher mean heart weight (p less than 0.05), a higher mean heart weight/body weight ratio (p less than 0.01), and a trend toward higher left ventricular systolic pressure levels (p less than 0.1). These hemodynamic responses in fetuses exposed to terbutaline may result in increased functional demands that may predispose myocardial tissue to damage.

Animals↗
PubMed2000

Modulation of mouse cardiac function in vivo by eNOS and ANP.

To study the role of endothelial nitric oxide synthase (eNOS) in cardiac function, we compared eNOS expression, contractility, and relaxation in the left ventricles of wild-type and eNOS-deficient mice. eNOS immunostaining is localized to the macro- and microvascular endothelium throughout the myocardium in wild-type mice and is absent in eNOS-/- mice. Whereas blood pressure is elevated in eNOS-/- mice, baseline cardiac contractility (dP/dt(max)) is similar in wild-type and eNOS-/- mice (9,673 +/- 2, 447 and 9,928 +/- 1,566 mmHg/s, respectively). The beta-adrenergic agonist isoproterenol (Iso) at doses of >/=1 ng causes enhanced increases in dP/dt(max) in eNOS-/- mice compared with wild-type controls in vivo (P < 0.01) as well as in Langendorff isolated heart preparations (P < 0.02). beta-Adrenergic receptor binding (B(max)) is not significantly different in the two groups of animals (B(max) = 41.4 +/- 9.4 and 36.1 +/- 5.1 fmol/mg for wild-type and eNOS-/-). Iso-stimulated ventricular relaxation is also enhanced in the eNOS-/- mice, as measured by dP/dt(min) in the isolated heart. However, baseline ventricular relaxation is normal in eNOS-/- mice (tau = 5.2 +/- 1.0 and 5.6 +/- 1.5 ms for wild-type and eNOS-/-, respectively), whereas it is impaired in wild-type mice after NOS inhibition (tau = 8.3 +/- 2.4 ms). cGMP levels in the left ventricle are unaffected by eNOS gene deletion (wild-type: 3.1 +/- 0.8 pmol/mg, eNOS-/-: 3.1 +/- 0.6 pmol/mg), leading us to examine the level of another physiological regulator of cGMP. Atrial natriuretic peptide (ANP) expression is markedly upregulated in the eNOS-/- mice, and exogenous ANP restores ventricular relaxation in wild-type mice treated with NOS inhibitors. These results suggest that eNOS attenuates both inotropic and lusitropic responses to beta-adrenergic stimulation, and it also appears to regulate baseline ventricular relaxation in conjunction with ANP.

Adrenergic beta-Agonists↗
PubMed1993

[Effect of percutaneous cardiopulmonary support (PCPS) on cardiac function with special reference to the significance of left ventricular venting].

Direct effects of percutaneous cardiopulmonary support (PCPS) on cardiac function were evaluated. Also, the efficacy of left ventricular venting to unload the heart was assessed. Eleven open-chested dogs were placed on PCPS with the flow equal to the baseline cardiac output for 30 minutes. Six out of eleven had left ventricle vented (VENT) by means of venting tube which was indwelt in the left ventricular cavity, while other five did not (NONVENT). Hemodynamic indices were obtained before and on PCPS. Measured, derived or calculated variables included heart rate (HR), mean aortic pressure (mean AOP), left ventricular end-diastolic pressure (LVEDP), peak left ventricular pressure (peak LVP), peak LVdp/dt, rate-pressure product (RPP, HR x peak LVP) and aortic-coronary sinus oxygen content difference (ACsO2D). There was no difference in any variables between the groups at baseline. On PCPS, in the VENT group, HR increased 27% from baseline (p < 0.05), while mean AOP did not change. All other variables showed significant (p < 0.05) reduction in VENT. Percent change from baseline value in VENT was: -24% for LVEDP, -47% for peak LVP, -41% for peak LVdp/dt, -32% for RPP and -42% for ACsO2D. No variable differed significantly from baseline in the NONVENT group on PCPS. The author concluded that left ventricular venting favorably alters the loading and contractile profile of the heart on PCPS without affecting systemic circulation.

Animals↗
PubMed2002

Decreased susceptibility of cardiac function to hypoxia-reoxygenation in renin-angiotensinogen transgenic rats.

We tested the hypothesis that the renin-angiotensin system (RAS) protects the contractile function of the myocardium against the damaging effect of hypoxia-reoxygenation. For this purpose, the contractility of isolated papillary muscles from wild-type (WT) rats and from rats expressing human renin and angiotensinogen as transgenes (TGR) was compared. After 15 min of hypoxia, peak force (PF) was decreased to 24 +/- 5% of the normoxic values in TGR (n = 10) and to 18 +/- 1% in WT rats (n = 12). PF and relaxation rates recovered completely in TGR but not in WT rats during 45 min of reoxygenation. Improved contractility of the papillary muscles from TGR during hypoxia-reoxygenation correlated with increased glutathione peroxidase activities and creatine kinase (CK)-MB and CK-BB isoenzyme levels. On the other hand, inhibition of the RAS with ramipril (1 mg/kg body wt for 3 wk) in WT animals resulted in deterioration of the contractile function of the papillary muscles during reoxygenation compared with untreated rats. These findings suggest that activation of the RAS protects contractile function of the cardiac muscle against hypoxia-reoxygenation, possibly through changes in CK isoenzymes and enhanced antioxidant capacity.

Animals↗
PubMed1986

Augmentation of cardiac function in end-stage heart failure by combined use of dobutamine and amrinone.

A patient with end-stage congestive cardiomyopathy had progressive hemodynamic deterioration while awaiting orthotopic heart transplantation. Attempts to support cardiovascular function by high-dose dobutamine infusions were complicated by life-threatening cardiac arrhythmias. The addition of the noncatecholamine inotropic agent, amrinone, improved ventricular performance, enabling reduction of the dose of dobutamine and resolution of the cardiac arrhythmias. Beta receptor stimulation by dobutamine combined with phosphodiesterase inhibition by amrinone may additively or synergistically augment cardiac function despite severe congestive heart failure and also have an adrenergic "sparing effect."

Aminopyridines↗
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↗