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PubMed1977

Graded global ischemia and reperfusion. Cardiac function and lactate metabolism.

The effect of global ischemia of different degrees of severity and reperfusion was studied in the isolated working rat heart. Four degrees of ischemia were induced by reducing the control total coronary flow of 8 ml/min to 0, 0.04, 0.4, or 0.8 ml/min for 30 minutes, after which the coronary flow was returned to the control level. After severe ischemia (0 and 0.04 ml/min ischemic coronary flow groups), recovery of contractility was to less than 30% of the control, pre-ischemic value of ventricular developed pressure and dP/dt, and irreversible cardiac contracture and an increased pacing threshold occurred. After moderate ischemia (0.4 and 0.8 ml/min ischemic coronary flow groups), contractile function recovered completely, ischemic contracture was rapidly reversible and the pacing threshold did not increase. The moderately ischemic groups were able to function at a stable, low level of contractility for the 30 minute ischemic period, whereas the severely ischemic groups had no contractile activity. The amount of calculated tissue lactate accumulation correlated with the occurrence of irreversible ischemic injury; the severely ischemic groups which failed to recover with reperfusion accumulated 3-5 times as much lactate as the moderately ischemic groups which recovered completely. The results suggest that relatively small differences in the severity of the ischemic condition can markedly affect the degree of tissue injury.

Animals↗
PubMed1983

Effect of hydration state on cardiac function in patients on chronic haemodialysis.

Haemodynamic studies were performed at rest and during exercise in five chronic haemodialysis patients at two different states of hydration, called "normal hydration" and "over-hydration" (mean change in body weight 2.9 kg). Apart from an increase in mean aortic pressure and cardiac index there were no signs of cardiac dysfunction at rest at normal hydration. On exercise the mean pulmonary artery and wedge pressure increased significantly while cardiac output doubled. Overhydration caused considerable increases in right and left sided heart pressures at rest, without any increase in cardiac index. These changes became more pronounced during exercise. Anaemia and arteriovenous shunting make dialysis patients very sensitive to volume load. Extreme anaemia should be avoided, and keeping dialysis patients in a state of low volume load should be given high priority.

Adult↗
PubMed2005

The heart of Sparus auratus: a reappraisal of cardiac functional morphology in teleosts.

This morphodynamic study provides an insight on how the architecture of the heart ventricle of the gilthead seabream (Sparus auratus) is designed to accomplish the functional performance typical of an active teleost species. Using an in vitro working heart preparation, mechanical performance was analyzed under loading (i.e., preload and afterload) challenges. The hearts were very sensitive to filling pressure increases. Maximum cardiac output (CO: 55.66+/-4.54 ml/min/kg body weight; mean+/-SEM) and maximum stroke volume (VS: 0.42+/-0.027 ml/kg body weight; mean+/-SEM) were obtained at an input pressure of 1 kPa. When exposed to output pressure (OP) changes, the hearts maintained constant CO and SV up to about 4 kPa; further increases of afterload significantly compromised mechanical performance. Surprisingly, this "athletic" pumping performance was achieved by an entirely trabeculated pyramidal ventricle. The ventricular architecture was characterized by a system of small luminae and trabecular sheets radiating outward from the central lumen. The most peripheral part of the ventricular chamber contained single trabeculae and the corresponding lacunary spaces. The ventricular cavity was bounded by an outer myocardial monolayer "shell" to which the peripheral trabeculae were attached. Myofibril organization differed in the trabeculae and in the outer monolayer. The structural features challenge common beliefs regarding the typical "athletic" teleost heart design.

Animals↗
PubMed2006

Genotype related differences in beta2 adrenergic receptor density and cardiac function.

INTRODUCTION: Several common polymorphisms of the beta2 adrenergic (ADRB2) have been described including a Glycine (Gly) for arginine (Arg) substitution at amino acid 16. In vivo studies have attributed phenotypic differences in the Arg16Gly polymorphism of the ADRB2 to differences in agonist-mediated desensitization. Some studies, however, have shown differences between genotype groups under non-agonist-mediated conditions suggesting baseline differences in receptor function or in receptor density. We sought to determine whether genetic variation of the ADRB2 influenced ADRB2 density and, consequently, resting cardiovascular function. METHODS: We measured ADRB2 density on isolated lymphocytes in 30 healthy subjects (15 homozygous for Arg, Arg16, and 15 homozygous for Gly, Gly16) matched for age, cardiovascular fitness, BMI, and gender. In addition, we measured cardiac output (Q), heart rate (HR), and stroke volume (SV) after 5 min of quiet rest in these same subjects. RESULTS: Arg16 subjects had lower receptor density (1220 +/- 78 vs 1574 +/- 110, mean +/- SE, P < 0.01) as well as lower resting cardiac output due to a reduced stroke volume, but a higher HR when compared with the Gly16 subjects (Q = 4.3 +/- 0.2 vs 5.0 +/- 0.3 L.min(-1), SV = 65 +/- 6 vs 86 +/- 7 mL.beat(-1), HR = 70 +/- 4 vs 60 +/- 3 beats.min(-1), for the Arg16 and Gly16 groups, respectively, P < 0.01). In addition, ADRB2 density for all subjects was positively associated with cardiac output (r = 0.428, P = 0.009) and stroke volume (r = 0.407, P = 0.001). CONCLUSIONS: These data suggest that the Arg16Gly polymorphism of the ADRB2 influences receptor density, which, in turn, contributes to resting differences in cardiac output and stroke volume.

Adult↗
PubMed1987

[Effect of brain death on hemodynamics and cardiac function: an experimental study].

An experimental model was designed to study hemodynamic and left ventricular functional changes in the course of and after brain death in 13 mongrel dogs. Brain death was induced by creating intracranial hypertension by inflating a balloon inserted into the subdural space. Hemodynamic parameters and left ventricular systolic function as assessed by echocardiography were measured before and during intracranial hypertension and 30 min and 1, 2, 3, 5 and 8 hrs after brain death. During intracranial hypertension, heart rate, systemic and pulmonary blood pressures, cardiac output and systemic vascular resistance raised significantly. After brain death, all parameters decreased rapidly and significantly, and then stabilized. On comparison with values obtained before intracranial hypertension, systemic blood pressure decreased markedly following brain death, while no marked change was noted in cardiac output. This result is attributable to a marked reduction in peripheral vascular resistance following the induction of intracranial hypertension. The left ventricular end-diastolic and end-systolic diameters did not change; consequently, fractional shortening did not change, either. The Weissler's index improved after brain death, reflecting a marked reduction in systemic vascular resistance. This indicates limited usefulness of afterload-dependent cardiac indices. At the agonal period of brain death, three of 13 dogs died because of ventricular fibrillation or a marked decline in systemic blood pressure. Within five to eight hours after brain death, seven dogs died because of intractable acidosis. These results represent the specific hemodynamic features occurring after brain death. It is thought that recognition of these features is useful in managing cases of brain death and in selecting donors for heart transplants.

Animals↗
PubMed1985

Effects of esmolol on cardiac function: evaluation by noninvasive techniques.

In a double-blind, randomized, crossover study, the effects of esmolol and propranolol were examined at rest and during peak upright exercise in 15 patients. At rest, both esmolol and propranolol significantly decreased heart rate, systolic blood pressure, rate-pressure product, left ventricular ejection fraction, cardiac index and right ventricular ejection fraction. During exercise, significant decreases were also found in heart rate, systolic blood pressure and cardiac index in both treatment groups. No significant differences were found between mean esmolol and mean propranolol measurements at rest and during exercise, except for the exercise systolic blood pressure, which was lower during esmolol infusion. Blood levels of esmolol decreased markedly by 30 minutes postinfusion, as did its beta-blocking action. Esmolol was well tolerated with no important local, systemic or laboratory abnormalities. Thus, the effects of esmolol on cardiovascular performance at rest and during exercise are similar to those of propranolol.

Adrenergic beta-Antagonists↗
PubMed2003

Cardiac natriuretic peptides:a proteomic window to cardiac function and clinical management.

Congestive heart failure (CHF) is a leading cause of adult hospitalization in the United States, and despite advancements in treatment, the disease remains a major clinical challenge. The chief symptom of CHF is dyspnea, but in the urgent-care setting, it is often difficult to distinguish between cardiac and pulmonary causes of this symptom. B-type natriuretic peptide (BNP) is mainly synthesized, stored, and released in the ventricular myocardium and is strongly induced during ventricular-wall tension or stretch. It can be measured rapidly at the point of care and can be used to differentiate cardiac from pulmonary etiologies of dyspnea. In addition to its diagnostic utility, it also has prognostic value and may help guide the treatment of patients with CHF. Thus, it is likely that future algorithms incorporating BNP levels and other clinical indicators will become available to guide critical-care physicians in making management decisions for their CHF patients.

Biomarkers↗
PubMed1981

Terbutaline and maternal cardiac function.

The effect of terbutaline sulfate on left ventricular size and performance was studied by M-mode echocardiography in pregnant women with premature labor. Patients with uterine activity initiated during either oxytocin challenge testing or induction of labor served as a comparison group. During terbutaline therapy, heart rate, ejection fraction, and cardiac output increased significantly. End-diastolic volume and systolic blood pressure (BP) were unchanged, and diastolic BP and end-systolic volume fell. No changes in echocardiographic or hemodynamic parameters were present during oxytocin-induced uterine activity. Terbutaline, as currently used to prevent premature labor, is a potent inotropic and chronotropic agent. Pulmonary edema accompanying terbutaline treatment is probably not due to cardiac failure.

Adolescent↗
PubMed1995

Cardiac function during orthotopic liver transplantation with venovenous bypass.

We have studied the effect of varying the flow of a venovenous bypass system during orthotopic liver transplantation. During these manipulations, central venous (n = 9) or pulmonary artery occlusion (n = 9) pressures were kept constant. There was no change in right ventricular systolic or diastolic function in either group, suggesting that any conformational change of the ventricle during bypass is not of functional significance. The extrapolated volume loading required to compensate for the absence of bypass is of the order of 3000 ml.

Adult↗
PubMedDate not supplied

[Early alteration of adrenergic cardiac function in parkinsonisms with Lewy bodies].

BACKGROUND: 123I-metaiodobenzylguanidine (123I-MIBG) myocardial scintigraphy is clinically used to estimate myocardial sympathetic damage in some forms of heart disease, autonomic nerve disturbance in diabetic neuropathy, and disturbance of the autonomic nervous system in neurodegenerative disease. In the present study, examinations were performed to clarify the rate and characteristics of cardiac sympathetic disturbance in Parkinson's disease (PD) and usefulness of 123I-MIBG myocardial scintigraphy to differentiate PD from the Lewy Body Disease (LBD). MATERIAL AND METHODS: 108 subjects were studied. There were 70 patients with PD, 21 patients with LBD, and 17 age-matched normal subjects without neurological disease. The clinical parameters evaluated were severity of the process (measured by Hoehn and Yahr Scale), vegetative manifestations, development time and use of medication taken. Myocardial adrenergic function was analyzed by imaging with 123I-MIBG. Early (15 min) and delayed (4 h) images of the thorax in the anterior view were obtained after injection of 123I-MIBG (111 MBq). The qualitative and semiquantitative 123I-MIBG uptake was quantified by calculating a heart-to-mediastinum ratio (HMR) and analyzed in a blind manner. RESULTS: The mean H/M ratio in patients with PD and LBD was significantly lower than in controls (p < 0.05). This is independent of development time, process severity, use of medication or vegetative manifestations. The HMR obtained in LBD patients is less clear than in PD. CONCLUSION: 123I-MIBG myocardial scintigraphy might detect early disturbances of the sympathetic nervous system in PD and LBD.

3-Iodobenzylguanidine↗
PubMed1986

Left intraventricular pressure-impedance diagrams (DPZ) to assess cardiac function. Part I: morphology and potential sources of artifacts.

Left ventricular function can be assessed with pressure-volume diagrams (DPV). Since there exists a relationship between ventricular volume changes and changes in intraventricular impedance (ZIV), we propose a diagram, DPZ, obtained from the intraventricular pressure (PIV) and the ZIV signals. This method was tested in 10 anesthetized mongrel dogs (morphine, sc, 30 mg/kg, and pentobarbital, sc, 5-7 mg/kg). PIV was measured with a Millar microtip catheter advanced under fluoroscopy via the femoral artery. ZIV was measured with a laboratory impedance meter (100 microA rms constant current, 12 kHz) in a tetrapolar configuration using another intraventricular catheter. ECG, aortic pressure and basal ZIV were also recorded to help identification of the different cardiac cycle phases on the diagram. Single-beat and multiple-beat loops were obtained in bradycardia and tachycardia to test for repeatability. These loops were always of a quadrangular-like shape with clockwise rotation. No attempt was made to calibrate the impedance axis in terms of volume. Apparent small volume changes in the isovolumic phases were probably due to ZIV catheter bending and/or movement. It is suggested that DPZ can serve in itself as a complementary evaluation tool of ventricular function by application of different maneuvers (physical, physiological of pharmacological).

Animals↗
PubMed1994

Angiotensin II receptor subtypes and cardiac function.

All the components of the renin-angiotensin system have been identified in the heart including the angiotensin II receptor subtypes AT1 and AT2. In the normal human heart, there is a decreasing receptor density from the right atrium to the left ventricle. In right atrial membranes prepared from pathological hearts, the percentage of AT1 receptor decreases with the severity of cardiac dysfunction whereas that of AT2 receptor increases. Treatment of hypertrophic rats with AT1 receptor antagonists inhibits cardiac hypertrophy and reverses the increase receptor density, indicating involvement of this Ang II receptor subtype. The role of the AT2 receptor is still largely unknown but it may be involved in cell growth and proliferation. The cloning of both AT1 and AT2 receptors as well as the availability of potent and selective antagonists will help us to understand better the functional role of Angiotensin II in cardiovascular disorders.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1987

Toxic effects of hypoxia on neonatal cardiac function in the rat: alpha-adrenergic mechanisms.

Stimulation of peripheral alpha-adrenergic receptors by circulating catecholamines derived from the adrenal medulla is essential for surviving neonatal hypoxia. In 1-day-old rats, where sympathetic innervation of cardiovascular sites has not yet developed, blockade of these receptors results in failure of cardiac performance from a progressive decline in sinus rate and atrioventricular conduction deficits. These effects are absent in 8-day-old rats, where sympathetic efferent innervation has become established.

Animals↗