RADIOFREQUENCY CATHETER ABLATION OF ACCESSORY PATHWAYS DURING ENTRAINMENT OF AV REENTRANT TACHYCARDIA

Radiofrequency ablation of accessory pathways must sometimes be done d uring orthodromic atrioventricular reentrant tachycardia when manifest anterograde accessory pathway conduction is absent or retrograde fusi on obscures accessory pathway location during ventricular pacing. Unfo rtunately, abrupt heart rate slowing upon radiofrequency induced termi nation of atrioventricular reentrant tachycardia often causes catheter dislodgment. We report our experience in circumventing this problem d uring radiofrequency ablation by using entrainment of atrioventricular reentrant tachycardia. The latter maintains retrograde activation pat tern over the accessory pathway while preventing abrupt ventricular ra te change. Eight patients (4 men and 4 women, mean age 37.3 +/- 17.9) with eleven left-sided accessory pathways were included. Ablation duri ng entrainment was used as the first approach in three patients with c oncealed accessory pathways and one patient with a bidirectional acces sory pathway. In another four patients, ablation during entrainment we ts used after technical difficulties in ablating during tachycardia. O nly 1-3 radiofrequency applications were required to eliminate the acc essory pathway using the entrainment technique. The catheter remained stable when accessory pathway conduction was interrupted by radiofrequ ency current. In conclusion, entrainment of atrioventricular reentrant tachycardia during radiofrequency application is useful for maintaini ng catheter position for accessory pathway ablation during atrioventri cular reentrant tachycardia.