Action potential duration restitution properties and ventricular fibrillation maintenance mechanism / 中华急诊医学杂志

ABSTRACT

Objective Toinvestigate the role of dynamic dispersion of electrical recovery in ventricular fibrillation maintenance mechanism.Method Thirty-seren male Yorkshire pigs weighing (23?2.5) kg at 3 months age were randomly divided into Sham-operated group and myocardial infarction group in which the first branch of left anterior descending coronary artery of animals was hgated.After 4 weeks,according to VF occurrence by programmed electrical simulation,the myocardial infarction hearts were divided into two groups, twelve hearts in VF (+) group or six hearts in VF (-) group;and the normal hearts were divided into two groups,five hearts in VF (+) group or ten hearts in VF (-) group.Action potential duration (APD) of subendocardial,subepicardial and mid-layer myocardium of left ventricular anterior wall were recorded simultaneously.The relationship between APD and diastolic interval was quantified as an electrical restitution curve.A Student's-test was used to specify differences between groups.Results At the fourth week after coronary artery ligation,eighteen myocardial infarction hearts and fifteen normal hearts were investigated.When investigating transmural dispersion of reporlarization (TDR) of left ventricle,there was no difference between VF (+) group and VF (-) group [ (20.43?7.01) ms vs (22.32?7.53) ms,P=0.45],although there was statistically significant between normal hearts and myocardial infarction hearts [ (15.66?4.45) ms vs (25.72?6.70) ms,P =0.001].The percentage of APD restitution slope exceed 1 and APD restitution slope maximum were high in the VF (+) group with myocardial infarction hearts and in the VF (+) group with normal hearts, lower in the the VF (-) with normal hearts and lowest in the the VF (-) group with myocardial infarction hearts.Conclusion Dynamic APD restitution properties may play an important role in the ventricular fibrillation maintenance mechanism.The APD restitution slope and not static TDR have prognostic value regarding ventricular fibrillation events.The hearts with the steepest of APD restitution curves has the greatest liability of ventricular fibrillation to happen.