Clinical relevance of cardiac arrhythmias generated by afterdepolarizations Role of M cells in the generation of U waves, triggered activity and torsade de pointes

AbstractRecent findings point to an importment heterogeneity in the electrical behavior of cells spanning the ventricular wall as well as importent differences in the response of the various cell types to cardioactive drugs and pathophysiologic states. These observations have permitted a fine tuning and, in some cases, a reevaluation of basic concepts of arrhythmia mechanisms. This brief review examines the implications of some of these new findings within the scope of what is already kaown about early and delayed afterdepolarizations and triggered activity and discusses the possible relevance of these mechanisms to clinical arrhythmias