Search Results
Results 601 - 650 of 1069
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Mercuro G - - 1999
We studied myocardial contractility by pulsed wave Doppler tissue imaging in 6 postmenopausal healthy women. According to a crossover, double-blind protocol, we randomized patients to treatment with transdermal patches of estradiol-17beta or matched placebo. Estradiol-17beta did not modify local systolic and diastolic functions. Thus, at least when acutely administered, estrogen ...
van der Velden J - - 1999
OBJECTIVE: In this study we investigated whether differences exist or develop in patients with aortic or mitral valve disease in myofibrillar contractile function and contractile protein composition between subendo- and subepicardial human ventricular tissue. Isometric tension, its calcium sensitivity and contractile protein composition were studied in left ventricular subendo- and ...
Owen V J - - 1999
BACKGROUND: Potential cardiac donors show various degrees of myocardial dysfunction, and the most severely affected hearts are unsuitable for transplantation. The cause of this acute heart failure is poorly understood. We investigated whether alterations in calcium-handling proteins, beta-adrenoceptor density, or the inhibitory G protein Gialpha could account for this phenomenon ...
Melvin D B - - 1999
Reducing a dilated left ventricle's radius by wedge resection lowers wall stress, improving performance. However, compliance falls, stroke volume improvement is limited, and, later, both functional deterioration and serious dysrhythmias are frequent. These all may result from loss of circumference, loss of contractile mass, and myocardial trauma, none of which ...
Kraut E J - - 1999
BACKGROUND: Depression of myocardial contractility occurs in septic shock. METHODS: Fourteen pigs were instrumented to measure cardiopulmonary dynamics after a challenge of Escherichia coli endotoxin (lipopolysaccharide endotoxin, LPS). A volumetric Swan-Ganz catheter was placed via the jugular vein, and a carotid arterial line was placed into the aortic root. Eight ...
Patel MK - - 1999
BACKGROUND: Palmitoyl carnitine accumulation during ischemia causes profound electrophysiological changes, resulting in arrhythmias. We studied the electrophysiological and contractile effects of palmitoyl carnitine. METHODS AND RESULTS: Extracellular recordings made by using the endocardial unipolar paced evoked response (PER) in isolated perfused rabbit hearts were compared with action potentials (AP) recorded ...
Kojda G - - 1999
The effects of exogenous and endogenous. NO on myocardial functions such as contraction, relaxation and heart rate have recently gained considerable scientific interest. .NO stimulates myocardial soluble guanylate cyclase to produce cGMP, which activates two major target proteins. A small increase in cGMP levels predominantly inhibits phosphodiesterase III, while high ...
Nagashima Y - - 1999
PURPOSE: The effects of propofol on sinoatrial pacemaker activity and myocardial contractility and its interaction with the autonomic nervous system were investigated in isolated, cross-circulated right atrial canine preparations. METHODS: An isolated right atrial preparation was perfused with heparinized arterial blood from an anesthetized support dog and changes in atrial ...
Cittadini A - - 1999
Until a few years ago, growth hormone (GH) and insulin-like growth factor-1 (IGF-1) were considered essential only to the control of linear growth, glucose homeostasis, and for the maintenance of skeletal muscle mass. A large body of evidence recently coming from animal and human studies has unequivocally proven that the ...
Brochet E - - 1998
OBJECTIVES: The purpose of this study was to assess early temporal changes in myocardial perfusion pattern by myocardial contrast echocardiography (MCE) and their relation to myocardial viability in patients with reperfused acute myocardial infarction (AMI). BACKGROUND: Myocardial contrast echocardiography no-reflow is associated with poor contractile recovery after AMI. However, little ...
Mariotti E - - 1998
Iron-induced cardiac disease is the primary cause of death in transfused patients with thalassaemia major. The beneficial effects of deferoxamine mesylate on clinical cardiac disease have been well described but the impact of therapy on subclinical cardiac dysfunction is unknown. To assess the reversibility of subclinical cardiac dysfunction we studied ...
Lee S - - 1998
Recently we have shown that the left ventricular end-systolic pressure-volume relation (ESPVR) of in situ rat hearts is an upward convex curve in contrast to the linear left ventricular ESPVR in dog and human hearts. Within the smaller left ventricular volume range, the left ventricular end-systolic pressure rose steeply with ...
McDonough K H - - 1998
Previous studies have demonstrated that sepsis, endotoxin, and cytokine administration cause myocardial dysfunction. Nitric oxide has been implicated in this dysfunction, since in isolated cardiac tissues, dysfunction is prevented when nitric oxide synthase (NOS) inhibitors are present. To determine whether nitric oxide produced by the inducible form of the enzyme ...
Meguro T - - 1998
The effects of verapamil administration or vagal stimulation on the mechanical restitution curve (MRC) were studied in order to better understand the modulation of left ventricular (LV) function by interventions that lower the ventricular rate of atrial fibrillation. The MRC and the postextrasystolic MRC were obtained in 11 dogs using ...
Natale E - - 1998
The influence of the calcium antagonist gallopamil on the contractility of asynergic viable myocardium after acute myocardial infarction treated with thrombolysis was investigated by two-dimensional echocardiography. Sixteen patients with > or = 1 viable segment(s), identified during the low-dose phase (up to 10 micrograms/kg/min) of a dobutamine echocardiographic test (up ...
Müllner M - - 1998
After successful resuscitation from cardiac arrest, prolonged contractile failure has been demonstrated in animal experiments. No systematic evaluation of myocardial contractility following successful resuscitation after human cardiac arrest exists. The aim of this study was to assess left ventricular contractility following human cardiac arrest with successful resuscitation. In 20 adult ...
Grupp I L - - 1998
The stimulation of cardiac alpha1-adrenergic receptors (AR) modulates the heart's inotropic response and plays a role in the induction of cardiomyocyte hypertrophy. We have analyzed transgenic mouse lines overexpressing a wild-type alpha1B-AR specifically in the heart. Basal level systolic and diastolic left ventricular (LV) contractile function was depressed both in ...
Schelbert H R - - 1998
Therapeutic approaches to left ventricular dysfunction in ischemic heart disease are likely to be guided by the answers to 2 major questions: (1) which mechanisms account for the deterioration or loss of contractile function, and (2) can contractile function be improved or restored therapeutically? Both questions can face considerable diagnostic ...
Heusch G - - 1998
When severe ischemia, such as that resulting from a sudden and complete coronary artery occlusion, is prolonged for more than 20-40 min, myocardial infarction develops, and there is irreversible loss of contractile function. When myocardial ischemia is less severe but nevertheless prolonged, the myocardium is dysfunctional but can remain viable. ...
New R B - - 1998
BACKGROUND: Because of methods required for obtaining isolated left ventricular myocytes, evaluation of the contractile function of isolated left ventricular myocytes in normal human patients has been limited. Accordingly, the goal of the present study was to develop a means to isolate human left ventricular myocytes from small myocardial biopsy ...
Baer F M - - 1998
During the past decade there has been intense clinical interest in the differentiation between scar tissue and postischemic viable myocardium and its relevance to patient treatment and outcome. Frequently used paradigms of myocardial viability are hibernation and stunning which both refer to reversible left-ventricular contraction impairment. Hibernation describes the concomitant ...
Rivera E S - - 1998
OBJECTIVES: This study sought to evaluate the effects of veno-venous ultrafiltration on myocardial contractility in children undergoing cardiopulmonary bypass (CPB) for repair of congenital heart defects. BACKGROUND: Ultrafiltration (UF) is currently used to diminish postoperative fluid accumulation following CPB in children. Previous reports indicate improvement in hemodynamics immediately after UF, ...
von Spiegel T - - 1998
Myocardial pump function and the performance of the entire cardiovascular system are determined by preload, afterload and contractility. The best clinical measure of preload is the end-diastolic volume of the heart, which can be assessed by ventriculography, echocardiography or by indicator dilution techniques. Afterload is basically the wall tension during ...
Panas D - - 1998
Proinflammatory cytokines (interleukin-1beta, tumor necrosis factor-alpha, and interferon-gamma; Cytomix) depress myocardial contractile work partially by stimulating expression of inducible nitric oxide (NO) synthase (iNOS). Because NO and peroxynitrite inhibit myocardial O2 consumption (MVO2), we examined whether this mechanism contributes to reduced cardiac work. In control isolated working rat hearts, cardiac ...
Declerck C - - 1998
BACKGROUND: Automated border detection (ABD) allows semiautomated measurement of left ventricular (LV) areas. They can be combined with left ventricular pressure signals to generate pressure-area loops and pressure-dimension indices of contractility. This study compared conventional indices of ventricular performance (fractional area change [FAC] and circumferential fiber shortening [Vcfc]) with pressure-dimension ...
Domanski Michael J. - - 1998
The aim of the present study was to develop a new noninvasive approach for the assessment of regional and global myocardial contractility without the need for pharmacological intervention to alter load. Thirty-four healthy adults and five adults with dilated cardiomyopathy (DCM) were studied. Patients with diabetes mellitus and hyperthyroidism were ...
Fontaine E R - - 1998
Coronary dysfunctions identified in the presence of chronic heart failure are an important pathophysiologic abnormality that influences the prognosis of the disease. Because the endothelin pathway plays a significant role in the increased peripheral vascular tone associated with heart failure, we hypothesized that the endothelin pathway may be involved in ...
Kadambi V J - - 1998
Phospholamban gene transcript levels are much lower in murine atria as compared to murine ventricles and this reduced phospholamban expression has been suggested to result in enhanced atrial contractile parameters. To delineate the functional role of phospholamban in murine atrium, the contractile parameters of isolated muscles from phospholamban knockout and ...
Scognamiglio R - - 1998
Sustained inotropic stimulation, such as dobutamine infusion, has the potential to cause an additional contractile deterioration in viable but chronically hypoperfused and dysfunctioning myocardium, by inducing ischemia. Postextrasystolic potentiation (PESP) represents a potent inotropic stimulus without risk of provoking ischemia, as it is instantaneous. In this study, we assessed the ...
Braun-Dullaeus R C - - 1998
Clinical reports indicate that cyclosporine is able to induce heart failure without rejection after heart transplantation. This supposition is supported by ex vivo animal studies, yet ex vivo studies do not account for the potential of counter-regulatory mechanisms, and the clinical observations seem rare in comparison with the number of ...
Takahashi M - - 1998
Microtubules of cardiac myocytes are increased in pressure-overloaded cardiac hypertrophy, which interfere with the actin-myosin crossbridge motion and depress muscle contractility. However, it is unknown whether microtubules are increased in non-hypertrophied, dilated cardiomyopathy and, if so, their increase could contribute to the depressed contractility. We assessed the contractile function of ...
Zhou M - - 1998
Although cardiac function is depressed during endotoxic shock, it remains controversial whether the ventricular contractility and structure are altered during sepsis. To resolve this issue, rats were subjected to polymicrobial sepsis by cecal ligation and puncture (CLP). At 2, 5, and 10 h after CLP (i.e., the early, hyperdynamic stage ...
Lüss H - - 1998
BACKGROUND: Myocardial hibernation and stunning are characterised by a reversible contractile dysfunction during and after ischaemia, respectively. Calcium homeostasis might be disturbed in hibernation and stunning due to altered expression of cardiac proteins involved in calcium handling. METHODS: In enflurane-anaesthetised swine the coronary blood flow through the left anterior descending ...
Paulson D J - - 1998
The results of clinical and animal studies suggest that a short term period of moderate secondary carnitine deficiency, in and of itself, does not have a major effect on the cardiac contractile function, although substrate oxidation may be altered. However, with longer durations of carnitine deficiency, alterations occur within the ...
Gauthier N S - - 1998
Adenosine, acting via A1 receptors, modulates heart rate and contractility, and provides myocardial protection during times of stress. A transgenic model of cardiac A1 overexpression was produced and it demonstrated cardiac protection from ischemia. Since A1 receptor stimulation can inhibit contractility under some conditions, the present study was undertaken to ...
Qi X L - - 1998
Endocardial and vascular myocardial capillary endothelium has been shown to modulate the contractile characteristics of myocardium by altering myofibrillar affinity for calcium. Although the release of endothelial-derived substances that modify myocardial contractility has been shown to be altered in certain physiologic and pathologic situations, until now no study has evaluated ...
Onwochei M O - - 1998
The primary objective of this study was to test the hypothesis that an increase in the alpha1-adrenoceptor tone would potentiate the myocardial biphasic contractile response to inorganic phosphate [Pi, the substrate of Na/Pi-cotransporter (NP)]. A second aim was to determine whether activation of alpha1-adrenoceptor is necessary for the NP-mediated increase ...
Pandey A S - - 1998
Endothelin-1 (ET-1) is known to have positive inotropic effects in isolated cardiac muscle strips. ET-1 levels are elevated in congestive heart failure (CHF). We investigated the effects of ET-1 on contractility and cardiac relaxation (lusitropy) of the intact healthy murine heart and myocarditic/cardiomyopathic heart by chronic oral treatment with a ...
Gosselin H - - 1998
Early after infarction, ventricular dysfunction occurs as a result of loss of myocardial tissue. Although papillary muscle studies suggest that reduced myocardial contractility contributes to this ventricular dysfunction, in vivo studies indicate that at rest, cardiac output is normal or near normal, suggesting that contractility of the remaining viable myocardium ...
Ross S - - 1998
BACKGROUND: The intravenous anaesthetic propofol has been shown to possess free radical scavenging activity and calcium channel blocking effects in a number of in vitro models. We decided to compare the effects of propofol with those of fentanyl on myocardial contractility during and after ischaemia to determine whether propofol could ...
Holubarsch C - - 1998
BACKGROUND: For reasons of simplicity, studies on isolated human myocardium have been conducted using exclusively isometric contractions, although positive inotropic interventions may differently influence force development, extent of shortening and myocardial work performance. We investigated human left ventricular failing and non-failing preparations comparing isometric versus isotonic, i.e., shortening contractions. RESULTS: ...
Douglas S A - - 1998
SB 209670 reduced basal mean arterial pressure (16%) without affecting left-circumflex coronary artery (LCX) flow, cardiac output, heart rate, or global/regional myocardial contractility. In vehicle-treated animals, i.e. endothelin (ET)-1 produced an initial hyperemic response in the LCX, followed by a secondary reduction in flow. This response was accomplished by decreases ...
Kelm M - - 1997
OBJECTIVE: It has been suggested that nitric oxide (NO) is involved in the regulation of myocardial function in a variety of diseases such as dilated cardiomyopathy, myocarditis, heart transplant rejection, and septic shock. However, the underlying mechanism of NO mediated reduction of cardiac contractility has not been clearly established so ...
Schrader N - - 1997
In a placebo-controlled, double-blind study, we investigated the hemodynamic effects of a single infusion of prostaglandin E ( 1 ) (PGE ( 1 ); 60 microg infused over a period of 2 hours, the unit dosage used in courses of treatment for peripheral occlusive arterial disease) in 20 patients with ...
Allen S J - - 1997
Although myocardial edema is associated with cardiopulmonary bypass (CPB) and cardioplegic arrest (CPA), interventions to expedite edema removal have not been investigated. The primary mechanism for the removal of excess interstitial fluid in the heart is myocardial lymphatic drainage, but lymphatic function can be impaired by decreased contractility because of ...
Ishibashi Y - - 1997
BACKGROUND: Basic fibroblast growth factor (bFGF) is highly expressed in the myocardium in some cardiac disorders, such as ischemia-reperfusion and cardiac allograft rejection. However, whether bFGF has any effects on myocardial contraction is unknown. METHODS AND RESULTS: We examined the effects of bFGF on myocardial contractility using isolated adult rat ...
Gatti P J - - 1997
Activation of the vagus nerve leads to decreases in sinoatrial (SA) rate, atrioventricular (AV) conduction, and myocardial contractility. Previous data are consistent with the hypothesis that vagal control of cardiac rate and AV conduction are mediated by two anatomically separated and physiologically independent parasympathetic intracardiac ganglia located in fat pads ...
Onishi K - - 1997
An increase in the responsiveness of the contractile machinery to Ca2+ could theoretically enhance the mechanoenergetics of the heart. To clarify this unresolved issue, we studied the effects of MCI-154, a Ca2+ sensitizer, on the mechanoenergetics in terms of the left ventricular contractility index [slope of end-systolic pressure-volume relationship (Emax)] ...
Weiss H R - - 1997
Nitric oxide has been shown to decrease myocardial contractility and O2 consumption. This study was designed to evaluate the hypothesis that nitric oxide-mediated increases in cyclic GMP require elevated cyclic AMP to produce cardiac depression. Using isolated, Langendorff-perfused rat hearts, we determined the effects of intracoronary nitroprusside (NP, 1 and ...
Lombardo A - - 1997
OBJECTIVES: We sought to investigate the effects of revascularization on the contractile reserve of dysfunctional myocardium. BACKGROUND: The improvement in dysfunctional but viable myocardium after revascularization is frequently less than expected from the amount of contractile reserve detected on dobutamine stress echocardiography. The fate of the contractile reserve, when it ...
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