Safety and cost of outpatient radiofrequency ablation of the slow pathway in patients with atrioventricular nodal reentrant tachycardia.

R adiofiequency ablation of atrioventricular (AV) nodal reentrant tachycardia has been shown to be an effective and safe treatment and to have a significant cost advantage over other forms of therapy.* In studies reported to date, patients were hospitalized for 2 to 10 days after slow pathway ablation to monitor for possible complications or a recurrence of the tachycardia.*s3 A previous study reported that radiofrequency ablation of accessory pathways can be performed safely on an outpatient basis: but no prior studies evaluated the safety of outpatient radiofrequency ablation of the slow pathway in patients with AV nodal reentrant tachycardia. Therefore, the purpose of this study was to evaluate the safety and cost of performing radiofrequency catheter ablation of the slow AV nodal pathway on an outpatient basis. The study population comprised 139 consecutive patients (38 men and 101 women, mean age 4.5 f 16 years) who underwent radiofrequency ablation of the slow pathway for treatment of AV nodal reentrant tachycardia at the University of Michigan Medical Center between August 30, 1991 and December 2, 1992. One hundred thirty-one patients did not have structural heart disease; 4 had coronary artery disease, and 1 each had mitral valve prolapse, mitral regurgitation or a dilated cardiomyopathy. The procedure was perJormed with patients in the fasting state after discontinuation of all antiarrhythmic medications for 224 hours and after informed written consent was obtained. Three 7 or 8Fr sheaths were positioned in the right femoral vein, and 3 quadripolar electrode catheters were positioned in the high right atrium, His bundle position and right ventricle. All patients received a 3,000 IU bolus of heparin intravenously after initial placement of catheters. Intravenous midazolam was used for sedation. An initial diagnostic electrophysiologic test was pet$ormed to determine the tachycardia mechanism, and the anterograde and retrograde conduction properties and refractory periods of the fast and slow AV nodal pathways. The ablation catheter was a ‘7Fr bipolar or quadripolar electrode catheter with a 4 mm distal electrode and 2 to 5 mm interelectrode spacing (EP Technologies, Inc., Mountain View, California, or MansJield-Scientific, Boston). Radiofiequency energy was delivered as an unmodulated sine wave at 500 KHz (EP Technologies) between the distal electrode of the ablation catheter and a large skin electrode on the back, and was applied at power outputs of 30 to 35 W for 30 seconds. The application was terminated immediately in the event of coagulum formation, AV block or the occurrence of ven-