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At least 1,207 records · Page 67Linked to original sources
PubMed1997

Coronary constriction impairs cardiac function and induces myocardial damage and ventricular remodeling in mice.

To establish whether coronary artery narrowing (CAN) in mice was accompanied by depressed ventricular function, tissue injury, and modifications in cardiac anatomy, the left coronary artery was constricted in FVB/N mice and the animals were killed 7 days later. CAN consisted of a 53% reduction in luminal diameter, which resulted in a twofold increase in left ventricular end-diastolic pressure. Left ventricular systolic pressure and left ventricular + and -dP/dt decreased 15, 21, and 11%, respectively. Left ventricular weight-to-body weight ratio increased 33%. This hypertrophic adaptation was characterized by a 9 and 20% increase in the longitudinal and transverse cavitary diameters, which provoked a 1.5-fold expansion in chamber volume. In contrast, wall thickness decreased 15%. These anatomic and functional changes induced a threefold elevation in diastolic stress. Foci of reparative fibrosis were found in the endomyocardium and epimyocardium, involving 2-3% of the tissue. Finally, myocyte loss in the ventricle was 15%, and myocyte hypertrophy was 38%. Impaired ventricular function, diastolic Laplace overloading, myocyte loss, and decompensated eccentric hypertrophy in mice after CAN mimic the ischemic cardiomyopathic heart in humans.

Animals↗
PubMed2000

Perioperative cardiac function and predictors for adverse events after transmyocardial laser treatment.

BACKGROUND: Previous studies have reported that mortality and morbidity after transmyocardial laser treatment (TML) mainly occur perioperatively. The present study was designed to evaluate left-ventricular function and identify risk factors for cardiac-related adverse events in this phase. METHODS: Forty-nine patients were studied. The inclusion criteria were angina pectoris Canadian Cardiovascular Society Angina Score (CCSAS) class III and IV refractory to medical therapy and untreatable by coronary artery bypass graft or percutaneous transluminal coronary angioplasty, age less than 75 years, left ventricular ejection fraction greater than or equal to 30%, and myocardial regions with reversible ischemia. Hemodynamic data and cardiac adverse events were registered. The follow-up time was 30 days. RESULTS: A transient decrease in mean cardiac index (CI) was observed, reaching its minimum immediately after end of the surgical procedure (1.8+/-0.4, p<0.01 vs. baseline). Two patients (4%) died during the postoperative period (30 days). Seventeen patients (35%) experienced adverse cardiac-related events, where CCSAS class IV, unprotected left main stem stenosis, and diabetes mellitus were identified as risk factors in a multivariate analysis. CONCLUSIONS: A transient impairment of left ventricular function was observed after TML. The morbidity and mortality after TML were almost exclusively cardiac-related, identifying CCSAS class IV, unprotected left main stem stenosis, and diabetes as risk factors.

Aged↗
PubMed1995

Comparison of the alteration of cardiac function by sevoflurane, isoflurane, and halothane in the isolated working rat heart.

OBJECTIVES: Despite its widespread use, little is known about sevoflurane's physiologic effects. The direct myocardial effects of sevoflurane were compared with both halothane and isoflurane. DESIGN: Administration of minimum alveolar concentration (MAC) fractions of anesthetic (0 to 3.0) was systematically varied to decrease the possibility of time-related effects on measured parameters. SETTING: Isolated rat hearts were perfused using a working heart model where the parameters affecting myocardial work were carefully controlled and monitored. PARTICIPANTS: To avoid confounding effects of prior anesthetic administration, hearts were removed from rats, after decapitation, in the absence of anesthetic. INTERVENTIONS: In the first series, isolated perfused rat hearts were exposed to one of the three anesthetics in doses of 0 to 1.5 times MAC. In the second series, hearts were exposed to either sevoflurane or isoflurane in doses of 0 to 3.0 times MAC. The following variables were measured: the rate of change of left ventricular pressure; aortic flow rate; cardiac output; left ventricular end-diastolic pressure; the time constant of isovolumetric relaxation; and coronary vascular resistance. Oxygen consumption was measured during the first series. MEASUREMENTS AND MAIN RESULTS: In the first series, all systolic variables were reduced in the presence of halothane when compared with either isoflurane or sevoflurane. Halothane affected diastolic function to a greater degree than either sevoflurane or isoflurane, as measured by the rate of relaxation and end-diastolic pressure. In the second series, at a dose of 3.0 times MAC, both sevoflurane and isoflurane decreased systolic and diastolic function, with a greater reduction in cardiac output, and peak aortic flow and higher left ventricular end-diastolic pressures observed with isoflurane. Coronary resistance and oxygen consumption were not affected by any of the anesthetics. CONCLUSIONS: These data suggest that sevoflurane depresses cardiac function less than either halothane in doses of 1.0 and 1.5 x MAC or isoflurane at doses of 3 x MAC.

Anesthetics, Inhalation↗
PubMed1990

Lack of effect of oral L-carnitine treatment on lipid metabolism and cardiac function in chronically diabetic rats.

L-Carnitine is necessary for the transfer of long-chain fatty acids into the mitochondrial matrix where energy production occurs. In the absence of L-carnitine, the accumulation of free fatty acids and related intermediates could produce myocardial subcellular alterations and cardiac dysfunction. Diabetic hearts have a deficiency in the total carnitine pool and develop cardiac dysfunction. This suggested that carnitine therapy may ameliorate alteration in cardiac contractile performance seen during diabetes. In this study, heart function was studied in streptozotocin diabetic rats given L-carnitine orally. Oral L-carnitine treatment (50-250 mg.kg-1.day-1) of 1- and 3-week diabetic rats increased plasma free and total carnitine and decreased plasma acyl carnitine levels. In both groups, myocardial total carnitine levels were increased. However, L-carnitine (200 mg.kg-1.day-1) treatment of diabetic rats for 6 weeks had no effect on plasma carnitine levels. Similarly, plasma lipids remained elevated whereas cardiac function was still depressed. These studies suggest that in the chronically diabetic rat, the route of administration of L-carnitine is an important factor in determining an effect.

Animals↗
PubMed2003

Assessment of cardiac function by echocardiography in conscious and anesthetized mice: importance of the autonomic nervous system and disease state.

In this study, the authors sought to evaluate the mechanisms responsible for echocardiographically determined differences in cardiac structure and function between conscious and anesthetized mice to determine whether such differences were more or less evident in diseased states. Cardiac parameters were determined by transthoracic echocardiography. Mice anesthetized with a mixture of ketamine and xylazine showed reductions in heart rate (HR, 252 +/- 16 beats/min versus 734 +/- 9 beats/min) and fractional shortening (FS, 35% +/- 2% versus 59% +/- 2%) compared with conscious mice. Conscious mice responded little to the beta-agonist isoproterenol or atropine, but showed profound reductions in HR and FS in response to the beta(1)-antagonist atenolol. In contrast, both isoproterenol and atropine led to increases in HR and FS in anesthetized mice. The stress in conscious animals was reduced by the sedative midazolam, leading to partial restoration of responses to isoproterenol. Mice with constitutive activation of the beta-adrenergic system, due to cardiac overexpression of beta(2)-adrenergic receptors or with heart disease (myocardial infarct and pressure-overload hypertrophy) showed few differences in functional parameters between conscious and anesthetized states, attributable to pre-existing activation of the sympathetic and beta-adrenergic systems, even during anesthesia. The results indicate that the autonomic nervous system plays a critical role in the observed differences in cardiac structure and function between anesthetized and conscious mice.

Anesthetics↗
PubMed1996

The role of the NO pathway in the control of cardiac function.

Nitric oxide (NO) acts as an autocrine- and paracrine-acting signaling autacoid that, among other functions, has been shown to regulate cardiac contractile responsiveness to beta-adrenergic and muscarinic cholinergic agonists. Nitric oxide (NO) is formed by the oxidation of one of two equivalent guanidino nitrogens in L-arginine by O2 to form NO and L-citrulline. This reaction is catalyzed by a family of enzymes termed NO synthases. Three distinct isoforms of NOS have been identified, each the product of a separate gene. Cellular constituents of cardiac muscle, including ventricular myocytes as well as microvascular endothelial cells, have been shown to express the "endothelial constitutive" isoform of NO synthase (ecNOS or NOS3) in vivo, and both cell types also express the NO synthase isoform induced by specific inflammatory cytokines (iNOS or NOS2) in vivo and in vitro. While NO-dependent intracellular signalling in cardiac myocytes clearly involves the activation of guanylate cyclase and downstream signalling by cGMP, there is accumulating evidence that non-cGMP-dependent regulatory signalling events are also initiated by NO. In addition, decreased contractile responsiveness of cardiac myocytes to beta-adrenergic agonists, following induction of NOS2 by inflammatory cytokines, requires the presence of insulin and the co-induction of enzymes responsible for production of tetrahydrobiopterin, a NOS co-factor. Inappropriate or excessive production of NO by cardiac myocytes and by microvascular endothelial cells likely contributes to the cardiac contractile dysfunction characteristic of the systemic inflammatory response syndrome and cardiac allograft rejection.

Animals↗
PubMed1999

Beta-adrenergic receptor blockade arrests myocyte damage and preserves cardiac function in the transgenic G(salpha) mouse.

Transgenic (TG) mice with cardiac G(salpha) overexpression exhibit enhanced inotropic and chronotropic responses to sympathetic stimulation, but develop cardiomyopathy with age. We tested the hypothesis that cardiomyopathy in TG mice with G(salpha) overexpression could be averted with chronic beta-adrenergic receptor (beta-AR) blockade. TG mice and age-matched wild-type littermates were treated with the beta-AR blocker propranolol for 6-7 months, starting at a time when the cardiomyopathy was developing but was not yet severe enough to induce significant cardiac depression (9.5 months of age), and ending at a time when cardiac depression and cardiomyopathy would have been clearly manifest (16 months of age). Propranolol treatment, which can induce cardiac depression in the normal heart, actually prevented cardiac dilation and the depressed left ventricular function characteristic of older TG mice, and abolished premature mortality. Propranolol also prevented the increase in myocyte cross-sectional area and myocardial fibrosis. Myocyte apoptosis, already apparent in 9-month-old TG mice, was actually eliminated by chronic propranolol. This study indicates that chronic sympathetic stimulation over an extended period is deleterious and results in cardiomyopathy. Conversely, beta-AR blockade is salutary in this situation and can prevent the development of cardiomyopathy.

Adenylyl Cyclases↗
PubMed2005

[Left ventricular geometric patterns and cardiac function in patients with chronic renal failure undergoing hemodialysis].

UNLABELLED: The aim of this study was to estimate the impact and prevalence of left ventricular geometric alterations and systolic and diastolic dysfunction in hemodialysis patients, as well as the relationship with cardiac troponin as a marker of myocardial damage. METHODS: 31 patients (pts), 19 males and 12 females, age 58.1+/-16.4 (26 on hemodialysis, 5 on peritoneal dialysis) and 31 healthy normal controls were enrolled. Echocardiography measurements were carried out according to the American Society of Echocardiography recommendations. Left ventricular mass was calculated, according to the Devereux formula and indexed to height and weight 2.7. Doppler echocardiography was performed to study diastolic function by measurements of isovolumetric relaxation period (IVRT), E wave deceleretion time (DTE) and E/A ratio. Cardiac troponin was measured by a third generation electro-chemiluminescence immunoassay. Statistical analysis was performed using the t-test for between-group comparisons and the Pearson and Spearman's tests to investigate correlations; p values of <0.05 were considered statistically significant. RESULTS: Eccentric hypertrophy was the most frequent pattern (n=17; 55%), followed by normal cardiac geometry (n=7; 23%), and concentric hypertrophy (n=5; 16%). Only 6% of pts (n=2) showed concentric remodelling. Systolic dysfunction was present in terms of endocardial parameters in 3 pts (9%) (fractional shortening <25%, EF<50%), but in terms of midwall myocardial shortening in 51% (n=16). Diastolic dysfunction was present in 87% (n=27) with a pattern of impaired relaxation (in 5 without left ventricular hypertrophy). E/A was negatively correlated with age (r=-0.41, p=0.02); DTE was positively correlated with posterior wall thickness (r=0.36, p=0.05) and interventricular septum thickness (r=0.45, p=0.01); cardiac troponin was positively correlated with age (r=0.50, p=0.00), left ventricular mass (r=0.41, p=0.02), posterior wall thickness (r=0.41; p=0.02) and interventricular septum thickness (r=0.39, p=0.03) but not with diastolic dysfunction parameters. No significant difference was found in terms of duration of dialysis between patients with normal left ventricular geometry and those with left ventricular hypertrophy, but a significant difference in age was found (p=0.03). Pts with diastolic dysfunction had more frequent hypotensive episodes during dialysis (p<0.01). CONCLUSION: Impaired geometry and cardiac function is frequently observed in pts undergoing hemodialysis. Diastolic dysfunction is associated to a geometric pattern of left ventricular hypertrophy, although it can be an isolated initial manifestation of myocardial damage. Depressed midwall myocardial shortening can discriminate left ventricular dysfunction better than traditional endocardial systolic indexes.

Adult↗
PubMed2003

Influence of peroxynitrite on energy metabolism and cardiac function in a rat ischemia-reperfusion model.

Ischemia-reperfusion generates peroxynitrite (ONOO-), which interacts with many of the systems altered by ischemia-reperfusion. This study examines the influence of endogenously produced ONOO- on cardiac metabolism and function. Nitro-L-arginine (an inhibitor of ONOO- biosynthesis) and urate (a scavenger of ONOO-) were utilized to investigate potential pathophysiological roles for ONOO- in a rat Langendorff heart model perfused with glucose-containing saline at constant pressure and exposed to 30 min of ischemia followed by 60 min of reperfusion. In this model, ischemia-reperfusion decreased contractile function (e.g., left ventricular developed pressure), cardiac work (rate-pressure product), efficiency of O2 utilization, membrane-bound creatine kinase activity, and NMR-detectable ATP and creatine phosphate without significantly altering the recovery of coronary flow, heart rate, lactate release, and muscle pH. Treatment with urate and nitro-L-arginine produced a substantial recovery of left ventricular developed pressure, rate-pressure product, efficiency of O2 utilization, creatine kinase activity, and NMR-detectable creatine phosphate and a partial recovery of ATP. The pattern of effects observed in this study and in previously published work with similar models suggests that ONOO- may alter key steps in the efficiency of mitochondrial high-energy phosphate generation.

Animals↗
PubMed2001

Development of an acute burn model in adult mice for studies of cardiac function and cardiomyocyte cellular function.

The increasing availability of mice with gene supplementation (transgenic), site-specific inactivation mutations (gene "knock-outs"), or site-specific genetic modification mutations (gene "knock-ins") has spurred interest in the development of murine trauma models. In this study, C57 BL/6 mice (28 g) were given a cutaneous burn over 40% total body surface area by applying brass probes (1 x 2 x 0.003 cm) heated to 100 degrees C in boiling water to the animals side and back for 5 s. Shams received anesthesia alone and not burn. Mice were killed 24 h post-burn to determine presence of partial-thickness or full-thickness burn injury, cardiac contractile function (Langendorff perfusion, n = 7 or 8 mice/group) or to examine cardiac myocyte cytokine secretion in isolated cardiomyocytes (collagenase perfusion, n = 4 or 5 mice/group). All mice were killed 24 h post-burn for subsequent cardiac or cardiomyocyte studies. Our studies confirm that this murine model of burn trauma produced mixed partial- or full-thickness burn injury, whereas there was no necrosis or inflammation in sham burn mice. Baseline hematocrits were similar in all mice (44+/-1) but decreased after burn trauma (37+/-1), likely because of the volume of fluid resuscitation and hemodilution. Burn trauma impaired cardiac contraction and relaxation as indicated by the lower left ventricular pressure (LVP) measured in burn (56+/-4) compared to that measured in shams (84+/-1 mmHg, P < 0.001), a lower rate of LVP rise (+dP/dt max, 1393+/-10 vs. 2000+/-41 mmHg/s, P < 0.002), and reduced LVP fall (-dP/dt max, 1023 - 40 vs. 1550+/-50, P < 0.001). These differences occurred despite similar coronary perfusion pressures and heart rates in both sham and burn mice. Ventricular function curves were shifted downward in the burn mice in the direction of contractile failure; in addition, hearts from burn mice had reduced LVP and +dP/dt responses to increases in coronary flow rate, increases in perfusate Ca2+, and to isoproterenol challenge (P < 0.05). Burn trauma promoted cardiac myocyte secretion of tumor necrosis factor (TNFalpha) (175+/-6 pg/mL) compared to that measured in shams (72+/-9 pg/mL, P < 0.05); burn trauma also increased cardiac myocyte secretion of interleukin 1beta (IL-1beta) (sham: 2+/-0.5; burn: 22+/-1 pg/mL, P < 0.05) and IL-6 (sham: 70+/-6; burn: 148+/-16 pg/mL, P < 0.05). Anti-TNFalpha strategies prevented burn-mediated cardiac contractile deficits. Burn trauma altered Ca2+ homeostasis in murine cardiomyocytes (Fura-2 AM loading). [Ca2+]i in myocytes from burns (185+/-4 nM) was higher than values measured in myocytes from shams (86+/-nM, P < 0.05). These data confirm that the murine burn model provides a reasonable approach to study the molecular and cell biology of inflammation in organ dysfunction after burn trauma.

Animals↗
PubMed1990

In vitro cardiac function in early sepsis.

The involvement of the myocardium in the injury resulting from bacteremia has been somewhat controversial. Recently, some investigators have suggested that the transition from an early stage of sepsis, in which the cardiovascular system is stable and mortality is relatively low, to the late or preterminal stage of sepsis is a result of cardiac dysfunction. Here, however, data are presented to show that contractile defects and loss of myocardial reserve occur even early during a septic episode, i.e., at a time when cardiac output is elevated or normal. Efforts to determine the mechanism of the cardiac dysfunction are described. These entail studies of whole heart performance under conditions of varying the calcium availability for contraction and assessment of subcellular organelle function. The data indicate that calcium dyshomeostasis may at least partially contribute to the cardiac dysfunction of sepsis. The in vivo adequacy of cardiac function probably results from the capacity of the myocardium in early sepsis to respond to catecholamine support of chronotropy and inotropy.

Animals↗
PubMed1981

Cardiac function in hypertrophied hearts from chronically exercised female rats.

Physiological cardiac hypertrophy was produced in female rats by subjecting them to a swimming program for 8 wk. Conditioned rats (C) had body weights similar to sedentary control rats (S), but hearts from C weighed 33% more than hearts from S. Heart function was assessed in an isolated working-heart apparatus at similar heart rates and aortic diastolic pressures and over a range of 5-20 cmH2O left atrial filling pressure (LAP). At any given LAP, absolute values for cardiac output and coronary flow were greater (p less than 0.001) in C than S, but when these values were normalized for dry left ventricular (LV) weight, no differences were observed. Peak LV systolic pressure and ejection fraction were greater (p less than 0.01) in C than S at all LAP. Derived measures of contractility calculated at the midwall demonstrated greater (p less than 0.01) velocity and extent of circumferential fiber shortening in C compared with S. Therefore, chronic swimming in female rats leads to enhanced contractile performance of the left ventricle despite a marked degree of hypertrophy. These results contrast with our earlier observations in female rats trained by running where neither hypertrophy nor enhanced function were observed.

Animals↗
PubMed1985

Echocardiographic assessment of cardiac function and morphology in patients with generalised lipodystrophy.

Because cardiomegaly has been observed in lipodystrophic patients we studied cardiac morphology and function with one- and two-dimensional echocardiography in addition to general cardiologic examination in a series of seven patients. Muscular hypertrophy with increased chamber size and myocardial indentations were found. Two patients had asymmetrical septal hypertrophy (ASH), and two patients demonstrated systolic anterior movement (SAM) of the mitral valve. Wall motion analysis showed anomalities in four patients during contraction, in three during the early relaxation phase. Since pathological findings, probably increasing with age, were made in the majority of the patients, these findings add an additional unfavourable aspect to the syndrome.

Adolescent↗