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PubMed1980

Exercise capacity and cardiac function in trained and untrained thyroid-deficient rats.

This study was undertaken to ascertain the extent that impairments in a) the oxidative capacity of skeletal muscle, b) cardiac functional and biochemical correlates of contractile capacity, and c) maximal oxygen consumption (VO2 max) can be reversed in thyroid-deficient (TD) female rats subjected to an 8-wk physical training (running) program. Compared with a normal control (NC) group, thyroid deficiency caused reductions in the following: VO2 max (-32%), skeletal muscle homogenate respiratory capacity (-50%), cardiac myosin ATPase (-58%), and in situ-derived ventricular dP/dt max (-58%) (P < 0.001). The training program restored to within normal limits skeletal muscle oxidative capacity and VO2 max, but it did not improve cardiac myosin ATPase, Ca2+ regulation of myofibril ATPase, and dP/dt max relative to TD sedentary rats. However, the heart weight-to-body weight ratio was highest among the three groups in the TD trained group. These findings suggest that maximal oxygen utilization capacity of TD rats can be normalized by physical training, even though intrinsic contractile capacity of the heart could not.

Adenosine Triphosphatases↗
PubMed1985

Effects of intracoronary and intravenous amrinone infusions in patients with cardiac failure and patients with near normal cardiac function.

The effects of intracoronary and intravenous infusions of amrinone were studied to distinguish the drug's direct cardiac actions from its peripheral vascular and neuroendocrine properties. Intracoronary infusions of amrinone were found to have no haemodynamic effect other than producing a slight reduction in the left ventricular ejection fraction and some suggestion of coronary vasodilatation in patients with impaired left ventricular function. They did not improve contractility, cardiac output, or filling pressures and had no significant effect on myocardial metabolism, although therapeutic concentrations of the drug were detected in coronary sinus blood. Intravenously administered amrinone reduced filling pressures and improved the cardiac index in all patients, but haemodynamic improvements were most pronounced in the patients with the worst cardiac function. These changes were accompanied by improvements in the indices of contractility only in patients in whom alterations in concentrations of free fatty acid, glycerol, and glucose suggested peripheral catecholamine release. In the patients with the best basal cardiac function intravenously administered amrinone produced a reduction in myocardial work and evidence of myocardial ischaemia, as a result of excessive reduction of coronary perfusion pressure and increased heart rate, without any appreciable increase in cardiac index. It is concluded that, at the concentrations of the drug that can be achieved in man without adverse effects, amrinone has no direct positive inotropic effect. Haemodynamic changes are predominantly the result of vasodilatation, although catecholamines may be released in some patients.

Adult↗
PubMed1990

Effects of metoprolol on rest and exercise cardiac function and plasma catecholamines in chronic congestive heart failure secondary to ischemic or idiopathic cardiomyopathy.

To define the effects of 2 months of metoprolol therapy on cardiac function, aerobic performance and sympathetic nervous system activity, metoprolol (75 to 100 mg/day) was administered to 10 patients with chronic congestive heart failure (CHF). Metoprolol was discontinued in 2 patients because of worsening CHF. In the remaining 8 patients, peak oxygen uptake increased significantly (14.8 +/- 3.0 to 16.1 +/- 2.5 ml/kg/min, p less than 0.05) as did the oxygen pulse (9.0 +/- 2.2 to 12.6 +/- 1.8 ml/beat, p less than 0.02). Resting heart rate (87 +/- 18 to 62 +/- 9 beats/min, p less than 0.05) and peak exercise heart rate (133 +/- 13 to 105 +/- 30 beats/min, p less than 0.02) were both reduced. Mean resting ejection fraction increased from 0.15 +/- 0.06 to 0.25 +/- 0.11 and peak exercise ejection fraction also tended to increase (0.19 +/- 0.11 to 0.28 +/- 0.15, difference not significant). Both resting plasma norepinephrine (613 +/- 706 to 303 +/- 142 pg/ml, p less than 0.05) and epinephrine (71 +/- 50 to 40 +/- 21 pg/ml, p less than 0.05) were reduced. Circulating lymphocyte beta-adrenergic receptor number was unchanged (1,334 +/- 292 to 1,344 +/- 456 receptors/cell, difference not significant). It is concluded that metoprolol therapy is associated with improvements in rest and exercise ventricular performance and maximal aerobic capacity. These improvements are associated with a decline in resting sympathetic nervous system activity.

Aged↗
PubMed1995

Cardiac function in smokers and nonsmokers: the CARDIA study. The Coronary Artery Risk Development in Young Adults Study.

OBJECTIVES: This study assessed clinical and echocardiographic measures of cardiac function at rest in smokers and nonsmokers to determine the associations of cigarette smoking with various measures of left and right ventricular performance. BACKGROUND: Whereas the immediate cardiovascular effects of cigarette smoking have been well described, the long-term effects in an otherwise healthy cohort have not. Of particular interest were associations with heart rate, left ventricular end-systolic stress and left ventricular mass because higher levels of these measures would suggest increased myocardial oxygen consumption. METHODS: In year 5 of the Coronary Artery Risk Development in Young Adults (CARDIA) study, 3,366 smokers and nonsmokers (ex-smokers were excluded) underwent echocardiography as well as assessment of heart rate, anthropometric measurements and blood pressure. Participants ranged in age from 23 to 35 years and were equally distributed by race and gender. Echocardiographic measures included pulsed Doppler pulmonary artery acceleration time (a decrease suggests increased pulmonary artery pressure), left ventricular mass, left ventricular end-systolic stress and left ventricular fractional shortening. RESULTS: All comparisons were between smokers and nonsmokers. Heart rate at rest was significantly higher in smokers by 1.5 to 5 beats/min in all race/gender groups except black men. In men who smoked, pulmonary artery acceleration time was significantly lower by 4 to 8 ms. Except for black male smokers, there was a trend toward increased left ventricular mass (3 to 8 g) in all race/gender groups, significant in black women. Left ventricular end-systolic stress was significantly higher in women who smoked (4 to 6 dynes/cm2). There were no differences for systolic blood pressure or left ventricular fractional shortening. CONCLUSION: In an assessment of cardiovascular function at rest in young adults, quantifiable differences between smokers and nonsmokers that predict increased rest myocardial oxygen consumption in smokers were found. Some of these differences were gender specific.

Adolescent↗
PubMed1991

Alterations in cardiac function and subcellular membrane activities after hypervitaminosis D3.

The present study was designed to induce massive accumulation of calcium in the myocardium and to evaluate the effect of calcium overload on myocardial contractile function and biochemical activity of cardiac subcellular membranes. Rats were treated with an oral administration of 500,000 units/kg of vitamin D3 for 3 consecutive days, and their hearts were sampled on the 5th day for biochemical analysis. On the 4th and 5th days, heart rate, mean aortic pressure, left ventricular systolic pressure and left ventricular dP/dt were significantly lowered in vitamin D3-treated rats, demonstrating the existence of appreciable myocardial contractile dysfunction. Marked increases in the myocardial calcium (67-fold increase) and mitochondrial calcium contents (24-fold increase) were observed by hypervitaminosis D3. Mitochondrial oxidative phosphorylation and ATPase activity were significantly reduced by this treatment. A decline in sarcolemmal Na+, K(+)-ATPase activity was also observed, while relatively minor or insignificant changes in calcium uptake and ATPase activities of sarcoplasmic reticulum were detectable. Electron microscopic examination revealed calcium deposits in the mitochondria after vitamin D3 treatment. The results suggest that hypervitaminosis D3 produces massive accumulation of calcium in the myocardium, particularly in the cardiac mitochondrial membrane, which may induce an impairment in the mitochondrial function and eventually may lead to a failure in the cardiac contractile function.

Adenosine Triphosphatases↗
PubMed1992

[Correlation analysis between plasma atrial natriuretic peptide and cardiac function in blood deficiency syndrome].

The function of ANP in the cardiovascular regulation is very similar with the TCM theory of "the Heart governs blood circulation". Using the method of cardiac impedance to check cardiac output and the method of radioimmunoassay (RIA) to check plasma ANP, the result showed that in the status of Blood Deficiency Syndrome, cardiac function was impaired, there were reduced kinemia and stroke volume, as well as markedly raised plasma ANP and peripheral resistance. The above-mentioned indexes were significantly different from those of normal group (P < 0.01). Using multivariate regression analysis, cardiac output was negatively correlated with the plasma ANP (P < 0.05). 23 cases with Blood Deficiency Syndrome showed normal hemoglobin, but an evidently changed cardiac output and plasma ANP were closely related with the level of the Blood Deficiency. Both parameters might serve as the objective basis to reflect the level of Blood Deficiency to facilitate the clinical diagnosis of the patient.

Adult↗
PubMed2004

Cardiac function and critical swimming speed of the winter flounder (Pleuronectes americanus) at two temperatures.

Using Transonic flow probes and a uniquely designed swimming flume, we directly measured cardiac parameters (Q, cardiac output; SV, stroke volume; and fH, heart rate) in winter flounder (Pleuronectes americanus) before and during critical swim speed (Ucrit) tests at 4 and 10 degrees C. Resting Q, SV and fH averaged 9.8 ml min(-1) kg(-1), 0.5 ml kg(-1) (1.0 ml g ventricle(-1)) and 21 beats min(-1) at 4 degrees C and 15.5 ml min(-1) kg(-1), 0.5 ml kg(-1) (0.95 ml g ventricle(-1)) and 34 beats min(-1) at 10 degrees C (Q10 values of 2.13, 0.91 and 2.35, for Q, SV and fH, respectively). Cardiac output, SV and fH increased by approx. 170%, 70% and 60% at both temperatures during the Ucrit test. However, cardiac parameters generally reached near maximal levels almost immediately upon swimming and remained at these levels until Ucrit (0.65 +/- 0.06 bl s(-1) at 4 degrees C and 0.73 +/ -0.07 bl s(-1) at 10 degrees C). This rapid rise in cardiac function to near maximal levels did not appear to be the result of stress alone, as Q only fell slightly when flounder were swum for 75 min at < 0.4 bl s(-1), speeds at which they appeared to swim comfortably. Our results suggest that both Q and Ucrit have been significantly overestimated in flatfishes, and that "lift-off"/slow swimming is energetically expensive. Furthermore, they show that maximum and resting stroke volume (per g of ventricle) are extremely high in the flounder as compared with other teleosts.

Animals↗
PubMed1990

[Cardiac function and reactivity in the late period following irradiation with high-energy protons].

Electrocardiography was used to analyze the results of 4-year investigations of the cardiac activity and reactivity (adrenalin test) in 32 dogs irradiated with high-energy protons (approximately 240 MeV) at absolutely lethal doses of 4 and 5 Gy. The author's and literature data have shown the similarity of cardiac functional features and reactivity in a long-term period in dogs with those in animals after radiation disease caused by exposure to some other types of ionizing radiations.

Acute Disease↗
PubMed1995

[The relationship between the improvement of cardiac function and the myocardial uptake of I-123 metaiodobenzylguanidine in patients with dilated cardiomyopathy treated by beta-blocker].

Chronic beta-blocker therapy improves hemodynamics and cardiac function in patients with idiopathic dilated cardiomyopathy. However, the change in myocardial uptake of I-123 metaiodobenzylguanidine (123I-MIBG) before and after treatment has not been determined. Myocardial imaging with 123I-MIBG was performed before and 2 or 3 months after beta-blocker (bisoprolol) therapy in 11 patients with dilated cardiomyopathy. The following parameters were compared before and after the treatment: 1) New York Heart Association functional class, 2) X-ray cardiothoracic ratio, 3) heart rate and blood pressure, 4) echocardiographic data (left ventricular end-diastolic and end-systolic diameters, and left ventricular ejection fraction), 5) plasma concentrations of epinephrine, norepinephrine and human atrial natriuretic peptide (HANP), and 6) exercise tolerance time by treadmill. The heart-to-mediastinum ratio of 123I-MIBG activities obtained 3 hours after intravenous injection (late H/M) and washout rate improved significantly after beta-blocker therapy. Cardiothoracic ratio, heart rate, echocardiographic parameters, HANP and exercise tolerance also improved significantly. Late H/M had no significant relationship with any of the clinical parameters, but washout rate was significantly related to left ventricular ejection fraction. These findings suggest that washout rate may be useful to assess the effect of short-term beta-blocker therapy in dilated cardiomyopathy patients.

3-Iodobenzylguanidine↗
PubMed2001

Effects of chronic food restriction and exercise training on the recovery of cardiac function following ischemia.

Clinical and experimental data suggest that exercise training (ET) and food restriction (FR) improve cardiovascular function. However, the effects of long-term FR or FR in combination with ET on the recovery of cardiac function following ischemia have not been determined. Male Wistar rats were assigned to ad libitum-fed, FR, ad libitum-exercise, and FR-exercise groups. Mechanical function of isolated working hearts was assessed in response to increases in afterload resistance and following global no-flow ischemia. At low workload, there was a significant FR effect on aortic flow as well as an interaction between FR and ET on systolic pressure. These effects remained when hearts were subjected to increases in aortic afterload resistance. During reperfusion of ischemic hearts, there was a significant FR effect on aortic flow and systolic pressure and a significant ET effect on diastolic pressure. An interaction between FR and ET on heart rate was also seen during reperfusion. In terms of percent recovery of heart function following ischemia, FR continued to affect aortic flow, and we observed an interaction between FR and ET on aortic flow. Our results clearly indicate that the myocardium from the FR animal or the FR, exercise-trained rat is more resistant to ischemia.

Animals↗
PubMed2024

The multifaceted role of mitochondria in cardiac function: insights and approaches.

Cardiovascular disease (CVD) remains a global economic burden even in the 21st century with 85% of deaths resulting from heart attacks. Despite efforts in reducing the risk factors, and enhancing pharmacotherapeutic strategies, challenges persist in early identification of disease progression and functional recovery of damaged hearts. Targeting mitochondrial dysfunction, a key player in the pathogenesis of CVD has been less successful due to its role in other coexisting diseases. Additionally, it is the only organelle with an agathokakological function that is a remedy and a poison for the cell. In this review, we describe the origins of cardiac mitochondria and the role of heteroplasmy and mitochondrial subpopulations namely the interfibrillar, subsarcolemmal, perinuclear, and intranuclear mitochondria in maintaining cardiac function and in disease-associated remodeling. The cumulative evidence of mitochondrial retrograde communication with the nucleus is addressed, highlighting the need to study the genotype-phenotype relationships of specific organelle functions with CVD by using approaches like genome-wide association study (GWAS). Finally, we discuss the practicality of computational methods combined with single-cell sequencing technologies to address the challenges of genetic screening in the identification of heteroplasmy and contributory genes towards CVD.

Humans↗
PubMed2003

Retrograde aortic isthmus net blood flow and human fetal cardiac function in placental insufficiency.

OBJECTIVE: Retrograde aortic isthmus (AoI) net blood flow has been associated with diminished oxygen delivery to cerebral circulation. This study was designed to characterize the cardiac function in human fetuses with retrograde AoI net blood flow in pregnancies complicated by placental insufficiency. METHODS: The control group comprised 43 fetuses in uncomplicated pregnancies. Study groups consisted of fetuses with placental insufficiency, and either antegrade (Group 1; n = 18) or retrograde (Group 2; n = 11) AoI net blood flow. Volume blood flows (Q) of left (LVCO) and right (RVCO) ventricles, ductus arteriosus (Q(DA)), pulmonary arterial bed (Q(P)) and foramen ovale (Q(FO)) were calculated and their proportions (%) of combined cardiac output (CCO) were determined. Ventricular ejection forces were calculated. Blood velocity waveforms of the mitral (MV) and tricuspid (TV) valves were obtained. The proportion of left ventricular isovolumetric relaxation time (IRT%) of the cardiac cycle, and index of myocardial performance (IMP) were calculated. RESULTS: In Group 1, Q(DA)% was increased (P < 0.05) and Q(P)% decreased (P < 0.05) compared with the control group, and Q(FO)% was greater (P < 0.01) compared with the control group and Group 2. In Group 2, the distribution of CCO did not differ from that of the control group. Ventricular ejection forces were similar among the groups. In Group 2, the MV early filling/atrial contraction time-velocity integral ratio was greater (P < 0.05) compared with those of the control group and Group 1. In Groups 1 and 2, IRT% and IMP were increased (P < 0.001) compared with the control group. CONCLUSIONS: In placental insufficiency, fetuses with antegrade AoI net blood flow show a shift in RVCO from the pulmonary to the systemic circulation, and Q(FO) makes up the majority of LVCO. Fetuses with retrograde AoI net blood flow fail to demonstrate these changes, suggesting a relative drop in the oxygen content of the blood entering the left ventricle.

Aorta, Thoracic↗
PubMed1983

[Monitoring of cardiac function during doxorubicin therapy in metastasized breast cancer. Measuring systolic time interval].

Assessment of systolic time interval represents an uncomplicated, sufficiently precise and cheap possibility in clinical practice of cardiac monitoring during treatment with doxorubicin (adriamycin) if the ratio between pre-ejection period interval (PEPI) and left ventricular ejection time interval (LVETI) ("Weissler index") for evaluation of left ventricular cardiac function is used. In an investigation of 352 female patients with metastatic carcinoma of the breast statistically ascertained dose-response relationships could be established as regards electrocardiographic disorders of repolarisation and the systolic time interval (P less than 0.001). Pre-irradiated patients showed more ECG changes (P less than 0.001) and higher PEPI : LVETI values (P less than 0.001) than patients without prior irradiation. There was no general influence of cytostatic treatment on systolic and diastolic blood pressure values. The upper limit of a therapeutic risk in evaluation of the systolic time interval for cardiac monitoring of doxorubicin treatment should be 0.45-0.50 for PEPI : LVETI. Above this borderline value precise cardiac evaluation including invasive methods should be attempted if continuation of treatment is indicated. This regime could help prevent the occurrence of life-threatening cardiac crises during treatment with doxorubicin.

Breast Neoplasms↗
PubMed2001

Effects of carnitine on cardiac function after cardioplegic ischemia in neonatal rabbit hearts.

BACKGROUND: Ischemia immediately impairs myocardial fatty acid metabolism and reduces the concentration of carnitine which is an essential cofactor for fatty acid metabolism in the mitochondria. The purpose of this study was to investigate the effects of carnitine administration on recovery of cardiac function after cardioplegic ischemia in the neonatal heart where fatty acid metabolism is not a predominant source of adenosine triphosphate. METHODS: Isolated blood-perfused neonatal rabbit hearts underwent 3 hours of cold cardioplegic ischemia. The control group (n = 10) was reperfused with unmodified diluted blood. The carnitine group (n = 10) was reperfused with the blood containing 5 mM/L of carnitine. Before ischemia (base line) and after 15 and 30 minutes reperfusion, left ventricular (LV) function and LV compliance were measured using a intraventricular conductance catheter combined with an isovolumic balloon. Coronary blood flow was measured and myocardial oxygen consumption was calculated. RESULTS: Carnitine significantly improved not only LV systolic function but also LV diastolic function (p < 0.05) as well as LV compliance after ischemia. Coronary blood flow and myocardial oxygen consumption were significantly improved after ischemia in the carnitine group compared with the control group (p < 0.05). CONCLUSIONS: These results suggest that carnitine strikingly improves LV functional recovery and aerobic metabolism after cold cardioplegic arrest, and may improve cardiac performance in neonates after open heart surgery.

Animals↗
PubMed2004

Viral-based myocardial gene therapy approaches to alter cardiac function.

In recent years there has been a rapid expansion in our understanding of the molecular biology that underpins human physiology. In the heart, elegant molecular pathways have been elucidated, and derangements in these pathways have been identified as factors in cardiac disease. However, as our understanding has grown, we have recognized that there exist only relatively crude tools to effect changes in molecular pathophysiology. The ultimate promise of gene therapy is to correct the molecular derangements that cause illness. To bring this promise to fruition in the clinical arena, many problems need to be solved, and chief among these remains reliable and robust delivery of genes to the target organ. To this end, viral vectors have been utilized with success more frequently than any other method of gene delivery. The use of these vectors in the heart has already offered promising novel benefit for human ischemic heart disease, and studies in animal models have given glimpses of hope that gene therapy may provide future therapeutic benefit in heart failure by improving cardiac function.

Animals↗
PubMed2004

Functional cardiac cell constructs on cellulose-based scaffolding.

Cellulose and its derivatives have been successfully employed as biomaterials in various applications, including dialysis membranes, diffusion-limiting membranes in biosensors, in vitro hollow fibers perfusion systems, surfaces for cell expansion, etc. In this study, we tested the potential of cellulose acetate (CA) and regenerated cellulose (RC) scaffolds for growing functional cardiac cell constructs in culture. Specifically, we demonstrate that CA and RC surfaces are promoting cardiac cell growth, enhancing cell connectivity (gap junctions) and electrical functionality. Being optically clear and essentially non-autofluorescent, CA scaffolds did not interfere with functional optical measurements in the cell constructs. Molding to follow fine details or complex three-dimensional shapes are additional important characteristics for scaffold design in tissue engineering. Biodegradability can be controlled by hydrolysis, de-acetylization of CA and cytocompatible enzyme (cellulase) action, with glucose as a final product. Culturing of cardiac cells and growth of tissue-like cardiac constructs in vitro could benefit from the versatility and accessibility of cellulose scaffolds, combining good adhesion (comparable to the standard tissue-culture treated polystyrene), molding capabilities down to the nanoscale (comparable to the current favorite in soft lithography-polydimethylsiloxane) with controlled biodegradability.

Action Potentials↗
PubMed1978

A comparison of the effects of quinetholate, lidocaine and procainamide on ouabain-induced ventricular tachycardia and cardiac function.

The antiarrhythmic effects of the quinoline derivative, quinetholate, on ouabain-induced tachycardia were compared with those of lidocaine and procainamide in dogs. In addition, the effects of these three agents on cardiac function were compared. Quabain was injected intravenously until ventricular ectopic beats accounted for at least 60% of the heart rate. Then one of the above antiarrhythmic agents was infused until sinus rhythm was reestablished for a minimum of 3 min or until it became evident that successful reversion would not occur. All three agents effectively reversed ouabain-induced ventricular tachycardia in most instances. Quinetholate was especially consistent, causing 16 reversions out of a total of 17 experiments. The relative molar antiarrhythmic potencies of the three agents in responding animals were as follows: lidocaine = 1.0, procainamide = 1.5, and quinetholate = 3.1. Quinetholate caused the longest lasting reversions, i.e. usually lasting at least 30 min after infusion was stopped. The degree of cardiac depression caused by the three agents at their mean effective antiarrhythmic doses was determined using the left ventricular function curve method. Lidocaine produced a significant depression of the ventricular function curve at the antiarrhythmic dose while procainamide and quinetholate did not.

Aminoquinolines↗
PubMed1978

Dobutamine in the treatment of depressed cardiac function: a study in patients with ischaemic heart disease during the early post-operative period.

Dobutamine was administered by intravenous infusion to 10 patients with ischaemic heart disease who had a low cardiac output syndrome following abdominal surgery. The dosage of dobutamine started from 2.5 mcg kg-1 min-1 and was increased stepwise to 5, 7.5, 10, 12.5 and 15 mcg kg-1 min-1. Cardiac index increased significantly from 2.05 +/- 0.32 to 3.03 +/- 0.61. min-1 min-2 with 15 mcg kg-1 min-1. Heart rate was unchanged with 7.5 mcg kg-1 min-1 but increased significantly from 97.7 +/- 18.5 to 126.1 +/- 21.5 beats. min-1 with 15 mcg kg-1. min-1. Stroke index increased significantly from 21 +/- 4.4 to 25.4 +/- 5.1 ml m-2. beat-1 with 7.5 mcg kg-1 min-1. Pulmonary wedge pressure fell significantly from 14 +/- 2.9 to 9.1 +/- 2.4 mmHg with 2.5 mcg kg-1 min-1. Mean arterial pressure showed no significant change. No side effects were observed in these patients. We conclude that in patients with depressed cardiac function dobutamine at low doses of 2.5 mcg kg-1 min-1 decreases afterload and filling pressures. At the average doses of 5 - 7.5 mcg kg-1 min-1 stroke index and cardiac index are increased. At higher doses of 10 - 15 mcg kg-1 min-1 heart rate and cardiac index increase while stroke index fails to increase further.

Aged↗