10 research outputs found
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Susceptibility of hypertrophied rat hearts to ventricular fibrillation during acute ischemia
This study compared arrhythmias induced by acute ischemia in Langendorff preparations of normal and hypertrophied rat hearts. Left ventricular pressure overload was induced by partial ligation of the abdominal aorta 6 to 8 weeks prior to study. The ratio of left ventricular weight to body weight (LVW/BW) and systolic blood pressure (SBP) were significantly higher in two groups of rats with hypertrophied hearts (moderate hypertrophy: 2.68±0.06 mg/g, 182±3 mm Hg; severe hypertrophy: 3.31±0.03 mg/g, 238±5 mmHg) than in normal hearts (2.18±0.03 mg/g, 125±3 mmHg), while there were no differences in body weights. During 30 min of ischemia produced by left coronary artery occlusion in the Langendorff preparations, ventricular fibrillation occurred in six of 20 (30%) normal, six of nine (67%) moderately hypertrophied, and 14 of 14 (100%) severely hypertrophied preparations (
P<0.001 normal vs severely hypertrophied). Tachyarrhythmias occurred in 15 of 20 (75%) normal, eight of nine (89%) moderately hypertrophied, and 14 of 14 (100%) severely hypertrophied hearts. Heart rate and coronary efflux before and during the ischemic period did not differ between normal and hypertrophied hearts. The ratio of non-perfused to perfused areas of the left ventricle, measured by Evans blue dye staining and with computerized planimetry, also was not different for normal (57.6±2.3%) and hypertrophied hearts (moderate hypertrophy 62.5±3.3%, and severe hypertrophy 59.1±2.0%). Additional control studies using larger hearts from older rats also indicate that myocardial mass was not an important determinant of ischemic arrhythmias in hypertrophy. Prolongation of endocardial and epicardial conduction time during 30 min of ischemia was not different between normal and hypertrophied hearts. Action potential duration and refractory periods were significantly longer in ventricular cells of hypertrophied hearts than in normals, and superfusion with hypoxia/zero glucose solution shortened these parameters to a greater extent in hypertrophied cells. These results lead us to conclude that hypertrophied hearts have a greater susceptibility to ventricular fibrillation during acute ischemia, and that dispersion of refractoriness may play a role in this phenomenon
Role of increased sympathetic activity in the genesis of ambulatory ischemia: Spectral analysis of heart rate variability
Increased cycle length variability during ventricular fibrillation: a novel predictor of arrhythmia recurrence
Early surgery with aggressive surgical approach to improve 6-month outcomes in patients with active infective endocarditis: contribution of cerebral preoperative magnetic resonance imaging
Tolerability, Efficacy, and Safety of Bisoprolol vs. Carvedilol in Japanese Patients With Heart Failure and Reduced Ejection Fraction - The CIBIS-J Trial -
Background: The comparative tolerability, efficacy, and safety of bisoprolol and carvedilol have not been established in Japanese patients with heart failure and reduced ejection fraction (HFrEF). Methods and Results: The CIBIS-J trial is a multicenter, open-label, non-inferiority randomized controlled trial of bisoprolol vs. carvedilol in 217 patients with HFrEF (EF <= 40%). The primary endpoint was tolerability, defined as reaching and maintaining the maximum maintenance dose (bisoprolol 5 mg/day or carvedilol 20 mg/day) during 48 weeks of treatment. The primary endpoint was achieved in 41.4% of patients in bisoprolol (n=111) and 42.5% in carvedilol (n=106) groups. The non-inferiority of tolerability of bisoprolol compared with carvedilol was not supported, however, neither beta-blocker was superior with regard to tolerability. Heart rate (HR) decreased in both groups and its decrease from baseline was significantly greater in the bisoprolol group (20.3 vs. 15.4 beats/min at 24 week, P<0.05). Plasma B-type natriuretic peptide (BNP) levels decreased in both groups and the decrease was significantly greater in the carvedilol group (12.4 vs. 39.0 % at 24 weeks, P<0.05). Conclusions: There were no significant differences between bisoprolol and carvedilol in the tolerability of target doses in Japanese HFrEF patients. The clinical efficacy and safety were also similar despite the greater reduction in HR by bisoprolol and plasma BNP by carvedilol