CATHETER ABLATION FOR THE COMMON TYPE OF ATRIOVENTRICULAR NODAL REENTRANT TACHYCARDIA

Radiofrequency (RF) catheter ablation of the slow AV nodal pathway was attempted in 34 patients with common type of AV nodal reentrant tachy cardia (AVNRT). Radiofrequency energy of 18-32 watts was applied for 3 0-60 seconds at sites exhibiting atrial-slow pathway potentials or slo w potentials. These potentials were recorded at the mid or posterior s eptum, anterior to the coronary sinus ostium. A mean of two radiofrequ ency applications successfully eliminated AVNRT in all patients. The i ncidence of junctional ectopy was significantly higher during 34 effec tive applications of radiofrequency energy than during 36 ineffective applications (100% versus 17%). Thus, the recording of atrial-slow pat hway potentials or slow potentials, and the development of junctional ectopy can be used as a marker for successful ablation. Slow AV nodal conduction was eliminated in 22 patients and persisted without inducib le AVNRT in 12. None of the patients had recurrences of AVNRT over a m ean follow-up interval of 12 months, and all had preserved AV conducti on. Longterm follow-up studies with an electrophysiological method con firmed that the ablation was effective. Transient AV block was observe d in only 1 patient, and no major complications were noted. Thus, radi ofrequency catheter ablation of the slow AV nodal pathway is highly ef fective and safe, with a low rate of complication, for the treatment o f common type of AVNRT.