Abstract 3385: Optimized Temporary Biventricular Pacing Acutely Improves Intraoperative Cardiac Output After Weaning From Cardiopulmonary Bypass
The benefit of cardiac resynchronization therapy via permanent biventricular pacing (BiVP) is well established in select patients with advanced CHF and intraventricular conduction delay. Patients with LV systolic dysfunction are at increased risk for acutely decompensated heart failure after cardiac surgery. Temporary, perioperative BiVP may improve hemodynamics in such patients. We assessed the hypothesis that optimized BiVP increases intraoperative cardiac output (CO). In 20 patients undergoing coronary artery bypass grafting and/or valve surgery with mean EF 33±3% and QRS 116±4 msec, BiVP was initiated at the conclusion of cardiopulmonary bypass using temporary epicardial pacing leads on the RA, RV, and LV. Changes in cardiac output (CO) during pacing were measured in real time with an electromagnetic aortic flow probe. Atrioventricular delay (AVD) was optimized by testing up to 7 settings from 90 to 270 msec, followed by interventricular delay (VVD) optimization with 9 settings from −80 msec (LV first) to +80 msec (RV first), each in random order. Optimized BiVP was then compared in random order to 2 controls: atrial (AAI) pacing at the same heart rate and sinus rhythm (NSR). Both AVD and VVD optimization resulted in significant differences in CO produced by the best, nominal, and worst settings (p<0.001). In post hoc comparisons, BiVP using optimized AVD (171±8 msec) and a nominal VVD of 0 msec increased mean CO by 14% vs. the worst setting (111±11 msec) (p<0.001) and by 7% vs. a nominal AVD of 120 msec (p<0.001). Optimizing VVD using the optimum AVD increased mean CO by 10% vs. the worst setting (p<0.001) and by 5% vs. a nominal VVD of 0 msec (p<0.001). CO differed among optimized BiVP, AAI, and NSR (p=0.003). Optimized BiVP increased mean CO by 13% vs. AAI at the same heart rate (CO 5.5±0.5 vs. 4.9±0.6 L/min at HR 97±3 bpm; p=0.003), and by 10% vs. NSR (5.0±0.6 L/min at HR 80±4 bpm; p=0.019). In conclusion, BiVP acutely increases intraoperative CO in patients with preoperative LV systolic dysfunction who are undergoing cardiac surgery. AVD and VVD each contribute to the overall benefit of BiVP optimization. The use of optimized temporary BiVP to treat postoperative low output states warrants further study.