The effect of the atrial pacing site on the total atrial activation time

The effect of dual site pacing for prevention of atrial fibrillation may be due to synchronization of right and left atrial activation. Little is know n, however, about the effect of pacing from single right atrial sites on di fferences in interatrial conduction. Twenty-eight patients without structural heart disease were studied followi ng radiofrequency catheter ablation of supraventricular arrhythmias. Pacing was performed using standard multipolar catheters from the presumed insert ion site of Bachmann's bundle, the coronary sinus ostium, the high lateral right atrium, and the right atrial appendage (n = 8 patients). Bipolar reco rding was performed from the distal coronary sinus, the high and low latera l right atrium, and the posterolateral left atrium (n = 13 patients). The l ongest conduction time from each pacing to each recording site was consider ed the total atrial activation time for the respective pacing site. During high right atrial pacing, the total atrial activation time was determined b y the conduction to the distal coronary sinus (118 +/- 18 ms), during coron ary sinus ostium pacing by the conduction to the high right atrium (94 +/- 28 ms), and during Bachmann's bundle pacing by the conduction to the distal coronary sinus (74 +/- 18 ms). The total atrial activation time was signif icantly shorter during pacing from Bachmann's bundle, as compared to pacing from other right atrial sites. Thus, in normal atria, pacing from the inse rtion of Bachmann's bundle causes a shorter total atrial activation time an d less interatrial conduction delay, as compared to pacing from other right atrial sites. These findings may have implications for alternative pacing sites for prevention of atrial fibrillation.