Steven Bailin

INTRODUCTION: Atrial pacing locations that decrease atrial activation and recovery time may be preferable in patients with a history of atrial arrhythmias. This multicenter prospective randomized study compared the efficacy of Bachmann's bundle (BB) region pacing to right atrial appendage (RAA) pacing in patients with recurrent paroxysmal atrial fibrillation (AF). METHODS AND RESULTS: Patients with standard pacing indications (n = 120, 70+/-11 years) were randomized to atrial pacing in either the RAA (n = 57) or BB region (n = 63). Implantation time was similar between groups (88+/-36 min [n = 38] for BB vs 83+/-34 min [n = 34] for RAA). No differences in pacing threshold, impedance, or sensing between BB and RAA groups were observed at implantation or after the 6-week, 6-month, and 1-year follow-up periods. Average length of follow-up was 12.6+/-7.4 months for the BB group and 11.8+/-8.0 months for the RAA pacing group. The percentage of atrial pacing was similar between groups (61%+/-34% RAA vs 65%+/-31% BB at 2 weeks after implant). BB atrial pacing significantly (P < 0.05) shortened p wave duration compared with sinus rhythm (123+/-21 msec vs 132+/-21 msec, n = 50) 2 weeks after implant. In contrast, p wave duration was longer during atrial pacing from the RAA position compared with sinus rhythm (148+/-23 msec vs 123+/-23 msec, n = 37). Additionally, p wave duration was shorter during BB pacing than during RAA pacing. Patients with BB pacing had a higher (P < 0.05) rate of survival free from chronic AF (75%) compared with patients with RAA pacing (47%) at 1 year. CONCLUSION: BB region pacing is safe and effective for attenuating the progression of AF.

AIMS: Ablation of atrioventricular nodal reentry tachycardia (AVNRT) has become treatment of choice because of a high success and low complication rate. Most ablations are successful in utilizing an anatomic approach, but anatomic variance, unusual pathway locations, or multiple pathways may complicate the procedure. Visualization of the slow pathway could expedite ablation success and enhance safety. Our purpose is to determine whether voltage gradient mapping can directly image the slow pathway and aid successful ablation of AVNRT. METHODS AND RESULTS: Three-dimensional voltage maps of the right atrial septum were constructed from intracardiac recordings obtained by contact mapping. Voltage values were adjusted until low-voltage bridging was observed within the Triangle of Koch. Forty-eight consecutive patients undergoing ablation for inducible AVNRT, underwent voltage gradient mapping. The slow pathway was identified in all 48 patients via its corresponding low-voltage bridge. Ablation of the slow pathway associated low-voltage bridges in 48 patients was successful in preventing reinduction following the first lesion in 43 of 48 patients. Five patients had multiple slow pathways and >1 lesion was required to prevent reinduction. Repeat mapping confirmed the absence of low-voltage connections previously observed in all 48 patients. CONCLUSION: Voltage gradient mapping can assist in visualization of the slow pathway. Ablation of the associated low-voltage bridge results in loss of slow pathway function and significant changes in the post-ablation voltage map. We conclude that voltage gradient mapping offers the ability to target the slow pathway for successful ablation.