VENTRICULAR-TACHYCARDIA AFTER MYOCARDIAL-INFARCTION - FROM ARRHYTHMIASURGERY TO CATHETER ABLATION

Ventricular tachycardia due to prior myocardial infarction is caused b y reentry. Intraoperative mapping at the time of arrhythmia surgery ha s shown that the reentry circuits are diverse in size and location. Ma ny circuits are large, extending over several square centimeters. Endo cardial excision guided by activation sequence mapping, fractionated s inus rhythm electrograms, or visual identification of scarred subendo- cardium renders 69% to 95% of patients free from inducible ventricular tachycardia, but with an operative mortality that exceeds 8% at most centers. Catheter ablation is difficult due to limitations of catheter mapping, relatively small size of lesions produced with current techn iques, and limited access to intramural and epicardial portions of the reentry circuits. Many problems need to be overcome for catheter abla tion to achieve success comparable to that of surgery. At present, onl y hemodynamically tolerated ventricular tachycardias can be mapped. Pr ogress is being made, and it is likely that catheter ablation will bec ome a viable therapy for subgroups of patients with postmyocardial inf arction ventricular tachycardia.