Search Results
Results 551 - 600 of 1130
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Li John K-J - - 2004
Mechanisms governing post-ischemic ventricular function after episodes of acute myocardial ischemia are still unclear. We investigated this stunned myocardial function with a computer model in conjunction with animal experiments. A modified lumped cardiac muscle model was subjected to parametric changes similar to regionally recorded ventricular parameters. The model was perturbed ...
Wang Lexin - - 2004
Previous studies have shown that an increase in coronary flow or shear force enhances the oxygen consumption and contractility of myocardium (the "Gregg effect"). Recent studies have indicated that an increase in coronary shear force also affects atrioventricular conduction and ventricular repolarization. The mechanisms of "Gregg effect" and the shear ...
Pádua-Filho Wagner C - - 2004
Beta-blockers and amiodarone have been used concomitantly to treat arrhythmias associated with congestive heart failure. However, the combination of metoprolol and amiodarone has only been studied restrospectively, and its potential effects in congestive heart failure remain to be properly elucidated in prospective trials. The present investigation focused on evaluating the ...
Barlow A J - - 2004
Controversy exists as to whether a hemodynamically significant left-to-right shunt due to a patent ductus arteriosus (PDA) affects ventricular contractility. Load-dependent indices such as ejection fraction and shortening fraction have traditionally been used to assess contractility, but the relationship between the rate-corrected velocity of fiber shortening (MVCFc) and wall stress ...
Korzick Donna H - - 2003
The primary purpose of this paper is to present a basic overview of some "relatively" new ideas related to the regulation of cardiac performance and underlying excitation-contraction (EC) coupling that have yet to be incorporated to textbooks currently used for introductory graduate-level physiology courses. Within the context of cardiac EC ...
Krenn Claus G - - 2004
Hemodynamic alterations are a well-known phenomenon that influence the outcome of orthotopic liver transplantation (OLT). Whether or not myocardial dysfunction, which has various causes, contributes to this instability is still debated. Previous transesophageal echocardiography (TEE) studies have presented controversial data, not leading to final clarification. This is mainly because the ...
Lewin Tal M - - 2003
Studies showing a correlation of excess myocardial triacylglycerol stores with apoptosis, fibrosis, and contractile dysfunction indicate that dysregulation of triacylglycerol metabolism may contribute to cardiac disease. This review covers the regulation of heart triacylglycerol accumulation at the critical control points of fatty acid uptake, enzymes of triacylglycerol synthesis, lipolysis, and ...
Mebazaa Alexandre - - 2004
The right ventricle (RV) provides sustained low-pressure perfusion of the pulmonary vasculature, but is sensitive to changes in loading conditions and intrinsic contractility. Factors that affect right ventricular preload, afterload or left ventricular function can adversely influence the functioning of the RV, causing ischaemia and right ventricular failure (RVF). As ...
Eichhorn Eric J - - 2003
BACKGROUND: beta-Blockers improve survival and reduce hospitalization in chronic heart failure (CHF) by biologically improving left ventricular ejection fraction (LVEF). However, a good predictor of improvement with this therapy has not been identified. This substudy of BEST examined whether myocardial contractile reserve, as determined by dobutamine stress echocardiography, predicts improvement ...
Heilmann Claudia A U - - 2003
OBJECTIVE: Growth factor gene therapy represents one current approach in the therapy of myocardial ischemia. We assessed the in vitro and in vivo expression of naked plasmid DNA aiming at preservation of function in a chronically ischemic myocardial model. METHODS: In vitro: Primary cardiac fibroblasts were transfected with plasmids encoding ...
Tatsumi Tetsuya - - 2004
The mechanisms by which endotoxemia causes cardiac depression have not been fully elucidated. The present study examined the involvement of nitric oxide (NO) in this pathology. Rats were infused with lipopolysaccharide (LPS) or saline, and the plasma and myocardial NO(2)(-) and NO(3)(-) (NOx) concentrations were measured before or 3, 6, ...
Hu Xiaojun - - 2003
BACKGROUND: Previous studies have shown that viable but stunned myocardium displays contractile reserve and exhibits cardiac cycle-dependent variations of integrated backscatter (CVIB), whereas infarcted myocardium does not. HYPOTHESIS: This study was designed to clarify whether assessment of the acoustic properties of the myocardium can predict contractile reserve in patients with ...
Javadpour Maryam M - - 2003
The thin filament protein cardiac troponin T (cTnT) is an important regulator of myofilament activation. Here we report a significant change in cardiac energetics in transgenic mice bearing the missense mutation R92Q within the tropomyosin-binding domain of cTnT, a mutation associated with a clinically severe form of familial hypertrophic cardiomyopathy. ...
Paz Y - - 2003
OBJECTIVE: The internal thoracic artery (ITA) is the most important graft in coronary artery bypass grafting. Its distal region is, however, prone to vasospasm. We studied the effects of nitroglycerin (NTG) and isosorbide-dinitrate (DSDN) on distal segments of left versus right ITA. METHODS: Rings of distal segments (6 to 9 ...
Wunderlich Carsten - - 2003
Elevated cardiac levels of nitric oxide (NO) generated by inducible nitric oxide synthase (iNOS) have been implicated in the development of heart failure. The surprisingly benign phenotype of recently generated mice with cardiac-specific iNOS overexpression (TGiNOS) provided the rationale to investigate whether NO scavenging by oxymyoglobin (MbO2) yielding nitrate and ...
Rapezzi Claudio - - 2003
Since a depressed contractility has long been considered the primary defect in patients with heart failure, the use of inotropic agents has been regarded as a logical approach to treat this syndrome. Despite this conceptual framework, these drugs have not yet established themselves in the treatment of chronic heart failure ...
Cremers Bodo - - 2003
Although there are some data on the cardiovascular profile of bupropion, a non-nicotine-based pharmacotherapy for smoking cessation, detailed studies of its specifically cardiac effects are lacking. In particular, the direct action of this agent on human myocardial contractility is not known. Therefore, we investigated the effects of bupropion on human ...
Conde Garcia E A - - 2003
Many pharmacological effects have been ascribed to extracts of Psidium guajava L. (guava) leaves. However, in spite of its widespread use in Brazilian folk medicine and a reasonable number of scientific reports about it, we could not find any study dealing with its action on the mammalian myocardium. In the ...
Zaugg C E - - 2003
Carnitine is essential for mitochondrial metabolism of long-chain fatty acids and thus for myocardial energy production. Accordingly, carnitine deficiency can be associated with cardiomyopathy. To better understand this disease, we determined myocardial function and energy metabolism in a rat model of carnitine deficiency. Carnitine deficiency was induced by a 3- ...
Klockgether-Radke A P - - 2003
BACKGROUND AND OBJECTIVE: Benzodiazepines may cause hypotension and are reported to interfere with smooth vascular muscle activity. The aim was to elucidate the influence of three different benzodiazepines on the vascular reactivity of coronary arteries. METHODS: Using the model of isolated vessels, we studied the impact of midazolam (0.15, 1.5, ...
Barnes Edward - - 2003
Myocardial stunning refers to the contractile dysfunction that occurs following an episode of acute ischaemia, despite the return of normal blood flow. The phenomenon was initially identified in animal models, where it has been very well characterised, and there was initial doubt about whether a similar syndrome occurred in humans, ...
Frangogiannis N G - - 2003
Myocardial hibernation refers to a state of persistent regional ventricular dysfunction, in patients with coronary artery disease that is reversible with revascularization. It is part of the spectrum of pathophysiological responses to myocardial ischemia and is a particularly important concept in understanding the development and progression of ischemic cardiomyopathy. Hibernating ...
Houser Steven R - - 2003
This review examines the evidence for and against the hypothesis that abnormalities in cardiac contractility initiate the heart failure syndrome and drive its progression. There is substantial evidence that the contractility of failing human hearts is depressed and that abnormalities of basal Ca2+ regulation and adrenergic regulation of Ca2+ signaling ...
Takahara Akira - - 2003
Y-27632, (+)-(R)-trans-4-(1-aminoethyl)-N-(4-pyridyl) cyclohexanecarboxamide dihydrochloride monohydrate, is a selective Rho-associated kinase inhibitor, which has been suggested to possess multiple clinical applications based on the in vitro observations. Since information regarding in vivo cardiovascular effects of Y-27632 is still limited, we assessed them using the halothane-anesthetized, closed-chest canine model. Administration of Y-27632 ...
Vogt Achim M - - 2003
In the current study on human hibernating myocardium (HHM), we tested the hypothesis that increased glycolysis might exert a positive effect during a supply-demand balance situation by augmentation of myocardial energy formation. In 14 patients HHM was preoperatively detected by clinical methods and validated by the recovery of contractile function ...
Noguchi Teruo - - 2003
In non-failing human myocardium, V1 myosin comprises a small amount (<10%) of the total myosin content, whereas end-stage failing hearts contain nearly 100% V3 myosin. It has been suggested that this shift in V1 myosin isoform content may contribute to the contractile deficit in human myocardial failure. To test this ...
Cremers Bodo - - 2003
Lysophosphatidic acid (LPA) is a phospholipid messenger, which is released from activated platelets and leukocytes. This study examined the effects of LPA on myocardial contractility and characterized the signal transduction pathway involved in these effects. Functional effects of LPA were determined in isolated, electrically driven human myocardial preparations and rat ...
Koch A - - 2003
OBJECTIVE: To determine if bradycardia during hyperbaric exposure is accompanied by a negative influence on myocardial contractility. METHODS: Accelerometer-based registration of myocardial compression waves with Seismocardiography (SCG) for noninvasive contractility monitoring. Comparative pulmonary artery (PA) catheter study (9 ICU-patients, mean = 67ys) with ejection-fraction (EF) equivalent versus sum of g-values ...
Squires Jeffrey E - - 2003
Blunted beta-adrenergic inotropism in stunned myocardium is restored by pharmacological (N-acetylcysteine) and metabolic (pyruvate) antioxidants. The ketone body acetoacetate is a natural myocardial fuel and antioxidant that improves contractile function of prooxidant-injured myocardium. The impact of acetoacetate on postischemic cardiac function and beta-adrenergic signaling has never been reported. To test ...
Xiao Shouzhong - - 2002
Although a very close relationship between the amplitude of the first heart sound (S1) and the cardiac contractility have been proven by previous studies, the absolute value of S1 can not be applied for evaluating cardiac contractility. However, we were able to devise some indicators with relative values for evaluating ...
Wagner Kay-Dietrich - - 2002
In this study we analyzed the susceptibility of contractile function of the myocardium to hypoxia-reoxygenation after infarction. For this purpose, the contractility of isolated papillary muscles from rats was studied at high oxygen tension (pO2 80 kPa) and during hypoxia (pO2 3 kPa) with subsequent reoxygenation at variable intervals between ...
Müller Frank U - - 2003
Congestive heart failure is the common endpoint of various cardiac diseases representing a leading cause of cardiovascular mortality in Western countries. Characteristic functional alterations of the failing heart are explained by expressional changes of myocardial regulatory proteins; however, little is known about underlying mechanisms regulating cardiac gene expression in the ...
Amedeo Modesti Pietro P Clinica Medica Generale e Cardiologia, University of Florence, Viale Morgagni 85, 50134, Florence, Italy. - - 2002
The role of angiotensin II in pressure overload is still debated because notwithstanding its effects on myocyte contractility angiotensin II is not an obligatory factor for the development of hypertrophy. To define the role of angiotensin II in acute pressure overload we studied the effects of AT1 blockade (valsartan 80mg ...
Mukherjee Rupak - - 2002
BACKGROUND: Adrenomedullin has been demonstrated to cause systemic vasodilation, and increased plasma adrenomedullin levels have been observed in cardiovascular disease states such as heart failure. While adrenomedullin receptors have been localized to the myocardium, the effects of adrenomedullin on human myocyte contractility remained unknown. METHODS AND RESULTS: Left ventricular myocytes ...
Chakraborti Sajal - - 2002
A considerable number of experimental, epidemiological and clinical studies are now available which point to an important role of Mg2+ in the etiology of cardiovascular pathology. In human subjects, hypomagnesemia is often associated with an imbalance of electrolytes such as Na+, K+ and Ca2+. Abnormal dietary deficiency of Mg2+ as ...
Min Jiang-Yong - - 2002
We monitored myocardial function in postinfarcted wild-type (WT) and transgenic (TG) mouse hearts with overexpression of the cardiac Na(+)/Ca(2+) exchanger. Five weeks after infarction, cardiac function was better maintained in TG than WT mice [left ventricular (LV) systolic pressure: WT, 41 +/- 2; TG, 58 +/- 3 mmHg; P < ...
Kofidis T - - 2002
INTRODUCTION: Myocardial infarction followed by heart failure represents one of the major causes of morbidity and mortality, particularly in industrialized countries. Engineering and subsequent transplantation of contractile artificial myocardial tissue and, consequently, the replacement of ischemic and infarcted areas of the heart provides a potential therapeutic alternative to whole organ ...
Thomas James A - - 2002
Both large burns and severe gram-negative sepsis are associated with acute myocardial contractile dysfunction. Because others have reported that burn injury may be followed by transient endotoxemia, we hypothesized that bacterial endotoxin induces contractile impairment after burn trauma. We tested this hypothesis in two rodent models. In each model, postburn ...
Iqbal Mobeen - - 2002
OBJECTIVES: To determine the time course for myocardial production of nitric oxide, peroxynitrite, and glutathione, to determine the activities of the myocardial antioxidant enzymes glutathione peroxidase, superoxide dismutase, and glutathione reductase throughout endotoxemia and into recovery, and to correlate the levels of these variables to left ventricular contractility in endotoxemia. ...
Burmeister Lynn A - - 2002
Subclinical thyrotoxicosis is defined as a below normal thyrotropin (TSH) in association with a normal total and free thyroxine (T4) and triiodothyronine (T3). It may be caused by thyroid hormone treatment or by endogenous thyroid disease. The degree of thyrotoxicosis may be estimated by the level of TSH suppression. Subclinical ...
Heusch Gerd - - 2002
Patients with chronic coronary artery disease frequently have contractile dysfunction that recovers upon reperfusion. The concept of myocardial hibernation views the observed reduction in contractile function not as the result of an ongoing energetic deficit, but as an adaptive down-regulation that serves to maintain myocardial integrity and viability. In the ...
Elsässer Albrecht - - 2002
OBJECTIVES: We tested the hypothesis that severe alterations in myocardial energy metabolism play an important role in the pathophysiology of human hibernating myocardium (HHM). BACKGROUND: It is well established that a disturbed myocardial energy metabolism results in impairments of contractile performance, structure and viability. All of these are important characteristics ...
Du Xiao-Jun - - 2002
Ca(2+) signaling plays a central role in cardiac contractility and adaptation to increased hemodynamic demand. We have generated mice with a targeted deletion of the S100A1 gene coding for the major cardiac isoform of the large multigenic S100 family of EF hand Ca(2+)-binding proteins. S100A1(-/-) mice have normal cardiac function ...
Kuhn M - - 2002
To investigate how permanent inhibition of guanylyl cyclase A receptor (GC-A) affects cardiac function. Hearts of GC-A-/- and corresponding wild type mice (GC-A+/+) were characterised by histological, western blotting, and northern blotting analyses. Cardiac function was evaluated in isolated, working heart preparations. At 4 months of age, GC-A-/- mice had ...
Sugiyama Atsushi - - 2002
Chronotropic, inotropic and coronary effects of Y-27632 ((+)-(R)-trans-4-(1-aminoethyl)-N-(4-pyridyl) cyclohexanecarboxamide dihydrochloride, monohydrate), a specific inhibitor of Rho-associated coiled-coil forming protein serine/threonine kinase (ROCK), were assessed using canine isolated, blood-perfused heart preparations. Y-27632 slightly enhanced sinoatrial automaticity and significantly increased coronary blood flow, while it decreased ventricular contraction. The concentrations of Y-27632 ...
Fang Zhibin - - 2002
Acute myocardial ischemia was induced by intravenous injection of pituitrin, and electroacupuncture (EA) was applied at the Heart and Lung Meridians (HM and LM), 3 points on each meridian. The changes in the left intraventricular pressure (LVP), the maximum rise rate of intraventricular pressure (LVP dp/dtmax), the area of cardiac ...
Saavedra Walter F - - 2002
Inhibition of xanthine oxidase (XO) in failing hearts improves cardiac efficiency by an unknown mechanism. We hypothesized that this energetic effect is due to reduced oxidative stress and critically depends on nitric oxide synthase (NOS) activity, reflecting a balance between generation of nitric oxide (NO) and reactive oxygen species. In ...
Kanzaki Hideaki - - 2002
BACKGROUND: Although right ventricular (RV) contractility is important in determining functional capacity, few quantification methods are clinically available. RV dP/dt(max) can be assessed by Doppler echocardiography by using tricuspid regurgitation (TR) but is not routinely used because of its dependency on a Doppler incident angle and preload. Doppler-derived dP/dt/P(max) is ...
Saavedra Walter F - - 2002
Inhibition of cardiomyocyte-specific ATP-sensitive potassium (K(ATP)) channels prolongs the action potential during intense ischaemia with attendant antiarrhythmic effects. However, this is accompanied by contractile depression in some models. These changes may be particularly troublesome in dilated cardiomyopathic hearts that display basal systolic dysfunction, limited energy reserve, and prolonged repolarization favouring ...
Heger Jacqueline - - 2002
Nitric oxide (NO), a potent regulator of myocardial contractility, has been implicated in the development of heart failure; however, no study exists describing the relation between expression of inducible nitric oxide synthase (iNOS), formation of NO in vivo, and cardiac contractility. We have therefore generated transgenic (TG) mice overexpressing iNOS ...
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