Comparison Between Biventricular Pacing and Single Site Pacing in Patients with Poor Ventricular Function:

Biventricular pacing has been suggested as offering greater hemodynamic benefit than single site pacing in patients with advanced heart failure and left bundle branch block. This was tested using acute multisite pacing. Eighteen such patients were atrialsensed, ventricular multisite paced in random order for 5 minutes. The best achieved measure of cardiac output (CO), pulmonary capillary wedge pressure (PCWP) and left ventricular (LV) + dP/dtmax at RV, LV, and biventricular pacing sites compared. Baseline PCWP, CO, and LV + dP/dtmax were 20 +/- 10 mmHg 4.8 +/- 1.3 L/min and 680 +/- 173 mmHg/s respectively. In all 18 patients CO and in 17 of 18 patients LV + dP/dtmax and PCWP improved with pacing. In the group as a whole, no significant hemodynamic difference between pacing sites was observed in PCWP (pacing site RV 19 +/- 10 mmHg, LV 17 +/- 10, biventricular 18 +/- 11) or CO (RV 5.2 +/- 1.5 L/min, LV 5.1 +/- 1.5, biventricular 5.3 +/- 1.7). Increased stroke volume/PCWP with LV (5.6 +/- 3.7 mLs/mmHg) and biventricular pacing (5.4 +/- 4.0) were not significantly greater compared to RV pacing (4.7 +/- 3.0, ANOVA P = 0.20). Increase in LV + dP/dtmax with pacing at LV (814 +/- 190 mmHg/s) and biventricular (839 +/- 290) sites was not significantly greater than the increase with RV pacing (769 +/- 203 mmHg/s, ANOVA P = 0.30). Pacing in patients with heart failure and conduction delay can produce a hemodynamic benefit. There is individual variation in the pacing site that leads to the greatest improvement. In the group as a whole, biventricular and LV pacing produced only modest improvements compared to RV pacing.