CARDIAC PACING OF BACHMANN BUNDLE DECREASES CUMULATIVE PERCENTAGE OF UNGROUNDED VENTRICULAR PACING

Abstract

To study influence of cardiac pacing of Bachmann bundle and the right auricle on atrio-ventricular conduction and cumulative percentage of ventricular pacing, 74 patients with the sick sinus syndrome were examined. Group I consisted of patients with atrial electrodes implanted into Bachmann bundle; in the patients of Group II, electrodes were implanted into the right auricle. The atrial electrode location was confirmed in three radilogical projections. The following standard indices were measured: pacing threshold, resistance and amplitude of endogram. Pacemakers of all subjects were programmed in the DDDR mode, with the minimal pacing rate of 60 bpm. The stimulated atrio-ventricular delay was programmed as constant and equal to 250 ms, and the sensed one was shorter by 20 ms. The cumulative percentage of atrial and ventricular pacing was assessed 6 months and 12 months after the procedure. In 6 months, in the patients of Group I (pacing of Bachmann bundle), the median of cumulative percentage of ventricular pacing was 6.8 times lower (6% [1.5 17.5%] and 41% [29 49.5%], respectively, p<0.001). The same tendency took place 12 months after the procedure (4% [2 18%] and 43% [32 52%], respectively, p<0.001), as well. In the patients with atrial electrodes located in the Bachmann bundle area, the cumulative percentage of ungrounded ventricular pacing is statistically significantly lower (in absolute values) in 6 months by 28%, on the average, and in 12 months by 29%. Thus, atrial pacing of Bachmann bundle as opposed the right auricle leads to a decrease in the cumulative percentage of ventricular pacing due to a higher likelihood of natural conduction through His bundle.