Abstract 20514: Improved Left Ventricular Synchrony with Parahisian and Mid-Septal Pacing Sites: Insights from Color Tissue Doppler Imaging
Background: Long term RV apical pacing may result in altered LV hemodynamics and a higher incidence of CHF and early death. Alternate site RV pacing may promote more physiologic ventricular depolarization and improved electro-mechanical synchrony. We evaluated the effect of alternate sites of RV pacing on short term synchrony and hemodynamics in children.
Methods: We prospectively analyzed 16 consecutive patients who underwent ablation for supraventricular tachycardia. Pacing was performed from 4 sites: Parahisian, RV mid-septum (MS), RV apex (RVA), and RV outflow tract (RVOT). Color tissue velocity imaging was performed to analyze time to peak systolic velocity (Ts) in a 12 segment model of the LV for each pacing site. Measurements included standard deviation of time to peak systolic velocity (SD-Ts) for all segments, maximal difference in Ts between any 2/6 basal (Ts-B), any 2/6 mid segments (Ts-M) and maximal Ts difference between any 2/12 segments (Ts-12). Stroke volume was estimated using Doppler time-velocity integral (TVI) in the left ventricular outflow tract (LVOT). QRS width for each site was recorded. Measurements were analyzed using an ANOVA mixed model with repeated measures.
Results: Ts-12 was significantly higher with RVA (101 ms, p=0.003) and RVOT (105 ms, p=0.001) pacing compared to sinus rhythm (48.6 ms),parahisian (45 ms)or MS (74 ms) pacing sites. SD-Ts was significantly higher with RVA (37.3 ms, p=0.02) and RVOT (26.5 ms, p=0.002) pacing compared to sinus rhythm (17.9 ms), parahisian (15.3 ms) or MS (29.9 ms) pacing. . QRS duration was longest for RVA (155 ms) and RVOT (146 ms) while significantly shorter for for SR (67 ms, p<0.0001), parahisian pacing (102 ms, p<0.0001) and MS pacing (119 ms, p<0.0001). LVOT TVI was significantly higher for parahisian than for RVA (p=0.0014), MS (p=0.04) or RVOT (p=0.003) pacing. Interobserver variability was excellent at 1.6% for SD-Ts and Ts-12 measurements.
Conclusions: Parahisian and mid-septal pacing offer superior electro-mechanical synchrony compared to RVA or RVOT pacing. This translates into improved hemodynamics in the short term with parahisian pacing.
- © 2010 by American Heart Association, Inc.