© 1998 by European Society of Cardiology
Copyright © 1998, European Society of Cardiology
Experimental models of torsade de pointes1
Hospital of the Westfälische Wilhelms-University, Department of Cardiology and Angiology and Institute for Arteriosclerosis Research, D-48129 Münster, Germany
* Corresponding author. Tel.: +49 (251) 834 7638, Fax: +49 (251) 834 7635, E-mail: l.eckardt@uni-muenster.de
Torsade de pointes is a potentially life threatening form of polymorphic ventricular tachycardia typically seen in the setting of congenital and acquired abnormal QT-prolongation. Numerous in vitro studies have investigated basic ionic mechanisms underlying delayed repolarization. The role of different ion channels and the induction of early afterdepolarizations have been studied in various cardiac cells including M cells. In addition, isolated heart models with and without electrical stimulation and/or the use of drugs which prolong repolarization have been developed in recent years. Some of these models have simulated conditions likely to exist in the clinical setting of torsade de pointes, such as bradycardia and hypokalemia. In in vivo canine and rabbit models, torsade-like polymorphic ventricular tachyarrhythmias have been induced by the administration of different agents such as cesium, neurotoxins, e.g., anthopleurin or various class III drugs under conditions designed to mimic the clinical situation. In the context of recent advances in the molecular genetics of long QT syndrome, those models which have used sodium or potassium channel blockers have gained particular interest. Based on all experimental studies it seems probable that the first beats of torsade occur due to early afterdepolarizations and triggered activity. The development of subsequent beats is less clear. Reentry based on inhomogeneity of refractoriness has been suggested as the underlying mechanism.
KEYWORDS Torsade de pointes; Experimental models; In vitro; In vivo; Long QT syndrome
1 Partly supported by the Franz Loogen Foundation, Düsseldorf, Germany.
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