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Intensive Exercise Training Improves Cardiac Electrical Stability in Myocardial‐Infarcted Rats

BACKGROUND: Moderate exercise training has been shown to decrease sudden cardiac death post myocardial infarction. However, the effects of intensive exercise are still controversial. METHODS AND RESULTS: Fourteen myocardial‐infarcted rats were divided into sedentary (n=8) and intensive training grou...

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Detalles Bibliográficos
Autores principales: Dor‐Haim, Horesh, Lotan, Chaim, Horowitz, Michal, Swissa, Moshe
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5586305/
https://www.ncbi.nlm.nih.gov/pubmed/28733433
http://dx.doi.org/10.1161/JAHA.117.005989
Descripción
Sumario:BACKGROUND: Moderate exercise training has been shown to decrease sudden cardiac death post myocardial infarction. However, the effects of intensive exercise are still controversial. METHODS AND RESULTS: Fourteen myocardial‐infarcted rats were divided into sedentary (n=8) and intensive training groups (n=6) and 18 sham control rats to sedentary (n=10) and intensive training groups (n=8). Heart rate variability was obtained at weeks 1 and 8. The inducibility of ventricular tachycardia/fibrillation was assessed in a Langendorff system. Fast Fourier transforms were applied on the recorded ventricular tachycardia/fibrillations. Training reduces low to high frequency ratio of heart rate variability at week 8 compared with that at week 1 (P<0.05). In isolated hearts, the probability for ventricular tachycardia/fibrillation was decreased from 4.5±0.8% in sedentary controls to 1.56±0.2% in intensive training controls (P<0.05) and from 13.5±2.1% in the sedentary group to 5.4±1.2% in the intensive training group (P<0.01). Moreover, the pacing current required for ventricular fibrillation induction in the trained groups was increased following exercise (P<0.05). Fast Fourier transform analysis of ECG findings revealed an exercise‐induced ventricular fibrillation transition from a narrow, single‐peak spectrum at 17 Hz in sedentary controls to a broader range of peaks ranging from 13 to 22 Hz in the intensive training controls. CONCLUSIONS: Intensive exercise in infarcted rats leads to reduced ventricular fibrillation propensity and is associated with normalization of refractoriness and intrinsic spatiotemporal electrical variations.