Class III actions in an experimental model of ventricular tachycardia.
Simplified models of re-entry may help in our understanding of the electrophysiologic effects of class III drugs. In a model of re-entrant ventricular tachycardia around a ring of epicardium in Langendorff-perfused rabbit hearts, the electrophysiologic effects of class III antiarrhythmic drugs were studied and compared to those of class I drugs. Class III drugs were effective in terminating fast re-entrant ventricular tachycardias. Prolongation of the refractory period without affecting conduction velocity resulted in a closure of the excitable gap and collision of the head of the propagating impulse against its own tail of refractoriness. In slow ventricular tachycardias, despite a similar increase in refractory period, the excitable gap remained large enough to allow perpetuation of the tachycardia.
Brugada
J
J
Department of Cardiology, University of Barcelona, Spain.
Boersma
L
L
Navarro-Lopez
F
F
Allessie
M
M
D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology*; D002839:Chromans; D004305:Dose-Response Relationship, Drug; D005260:Female; D006329:Heart Conduction System / Q000187:drug effects*; D008297:Male; D010477:Perfusion; D010880:Piperidines; D011817:Rabbits; D017180:Tachycardia, Ventricular / Q000188:drug therapy*
D000889:Anti-Arrhythmia Agents; D002839:Chromans; D010880:Piperidines; C063899:terikalant