INDUCTION OF TRANSIENT 3RD-DEGREE ATRIOVENTRICULAR-BLOCK DURING RADIOFREQUENCY CATHETER ABLATION IN A PATIENT WITH VENTRICULAR-TACHYCARDIA AND REMOTE MYOCARDIAL-INFARCTION

Introduction: Radiofrequency catheter ablation has been demonstrated t o be an effective with so-called idiopathic ventricular tachycardia, w hereas the benefit/risk profile for ablation in patients with chronic myocardial infarction and severely compromised left ventricular. funct ion still needs to be determined. The present report describes the uni ntended induction of transient third-degree atrioventricular block in a patient with remote myocardial infarction who underwent radiofrequen cy catheter ablation of ventricular tachycardia. Methods and Results: Endocardial catheter mapping and I radiofrequency ablation were perfor med in a 57-year-old patient with chronic recurrent ventricular tachyc ardia, who had previously suffered from myocardial infarction. Additio nally, the patient presented with complete right bundle branch block d uring sinus rhythm. Radiofrequency energy applied to a critical site o f the reentrant tachycardia at the left ventricular basal septum durin g sinus rhythm induced third-degree atrioventricular block after 20 s of current delivery, which lasted for 24 h. At this site a presumable left bundle branch potential was recorded during sinus rhythm. Conclus ions: Radiofrequency current application for ablation of ventricular t achycardia may induced third-degree atrioventricular block in patients with remote myocardial infarction. When current is delivered to ventr icular basal septum, radiofrequency energy should be applied during si nus rhythm to allow continuous monitoring of atrioventricular conducti on. Special caution should be given to patients with right bundle bran ch block during sinus rhythm.