Ventricular arrhythmias induced by endothelin-1 or by acute ischemia: a comparative analysis using three-dimensional mapping

Objectives: To analyze three-dimensional activation patterns of ventricular arrhythmias induced by endothelin-l in comparison with ischemia-induced ta chycardias. Methods: Following AV node ablation, sixty pin electrodes conta ining four bipoles each were inserted into both ventricles of ten foxhounds . Using a computerized mapping system, this would allow to simultaneously r ecord 240 endo-, epi and midmyocardial electrograms for reconstruction of t he three-dimensional activation pattern. In five dogs, endothelin-l was inf used into the LAD at 60 pmol/min. In another five animals, the LAD was liga ted. During the following 40 min, all ventricular arrhythmias were recorded for subsequent analysis. Furthermore, left ventricular conduction times du ring constant pacing and local effective refractory periods at eight left v entricular sites were determined before and after either intervention. Resu lts: Endothelin-l had no significant effect on conduction time and refracto riness, whereas ligation prolonged both parameters significantly. Endotheli n-l as well as ligation induced multiple mono- and polymorphic nonsustained ventricular tachycardias. Endothelin-l-induced arrhythmias were exclusivel y based on focal mechanisms, whereas during ligation, macroreentrant mechan isms were involved in the maintenance of tachycardias in 39% of episodes. C onclusion: The differences in the effects of endothelin-l and LAD ligation on electrophysiologic properties and the difference in the mechanism of ind uced ventricular tachycardias support the hypothesis that, apart from vasoc onstrictive properties, endothelin-l exerts an intrinsic arrhythmogenic eff ect. (C) 2000 Elsevier Science BN. All rights reserved.