Influence of left ventricular filling profile on the effect of atrioventricular synchronous pacing.

Abstract

We correlated the percentage of atrial contribution to left ventricular filling (percent AC) assessed by Doppler echocardiography with the hemodynamic benefit from atrioventricular synchronous pacing assessed by direct hemodynamic measurements. Subjects comprised 40 patients who underwent electrophysiologic catheterization because of unexplained syncope or bradycardia (< 40 beats/min). Femoral arterial and pulmonary capillary wedge pressure were recorded by catheterization, and cardiac output was measured by thermodilution during temporary atrioventricular synchronous (DDD, 70 beats/min with 150 ms of atrioventricular delay) and ventricular (VVI, 70 beats/min) pacing. Mitral inflow velocity by pulsed-wave Doppler echocardiography was recorded during DDD pacing and percent AC was obtained by calculating the ratio of mitral inflow velocity area during atrial systole to total mitral inflow velocity area during early diastole and atrial systole. The mean arterial pressure and the cardiac output increased significantly (99 +/- 16 mm Hg vs 90 +/- 15 mm Hg, p < 0.001; 4.6 +/- 1.0 L/min vs 3.9 +/- 0.9 L/min, p < 0.001), and the mean pulmonary capillary wedge pressure decreased (7 +/- 4 mm Hg vs 10 +/- 4 mm Hg, p < 0.001) during DDD compared with VVI pacing. A significant positive correlation was observed between the percent AC and the increase in cardiac output (r = 0.58, n = 40, p < 0.01) or the increase in mean arterial pressure (r = 0.62, n = 38, p < 0.01) during DDD pacing. The percent AC did not significantly correlate with the decrease in pulmonary capillary wedge pressure. In conclusion, patients with larger percent AC may receive major benefit from atrioventricular synchronous pacing.