Physical training modifies the spectral characteristics of ventricular fibrillation without the direct participation of parasympathetic postganglionic neurons

Autores UPV
Año
CONGRESO Physical training modifies the spectral characteristics of ventricular fibrillation without the direct participation of parasympathetic postganglionic neurons

Abstract

Introduction: Physical training can prevent against cardiacsudden death, produced by ventricular fibrillation (VF). Although the exact mechanisms are not known, some authors have involved the electrical remodeling and the increase of parasympathetic activity. We hypothesized that physical training modifies the electrophysiological characteristics of trained hearts during VF and that parasympathetic postganglionic neurons are implicated in those changes. Material and methods: NZW rabbits were divided in trained (n=11), control (n=10) and sham (n=10). Trained animals were submitted to a six-week training protocol, after which their hearts were isolated and perfused in a Langendorff system. Pacing and recording electrodes were positioned on the left ventricle. VF was induced by pacing and maintained 300s, without interrupting perfusion, before and during atropine (control and trained) or vehicle (sham) infusion. We determined: a) the dominant frequency (DF) of VF, b) the spectrum normalized energy (NE), c) the regularity index (RI), and d) DF, NE and RI regions of interest (ROIs) number and area. Paired and unpaired t-test were applied for statistical analysis. Results: Electrophysiological heterogeneity during VF was lower in trained hearts, as shown by the decrease in DF (16.4±3.4 vs 13.5±1.2) and the increase in NE (0.36±0.05 vs 0.40±0.05). ROIs were significantly lower in number and bigger in area in trained animals for DF and NE. No differences were observed after parasympathetic blockade within control and trained groups, or in sham hearts after vehicle infusion. Conclusion: Physical training modifies the spectral characteristics of VF and decreases the electrophysiological heterogeneity of ventricular myocardium without the direct participation of parasympathetic postganglionic neurons.