The hemodynamic effects of different pacing modalities after cardiopulmonary bypass in patients with reduced left ventricular function

Objectives: Patients with decreased left ventricular function undergoing cardiac surgery have a greater chance of difficult weaning from cardiopulmonary bypass and a poorer clinical outcome. Directly after weaning, interventricular dyssynchrony, paradoxical septal motion, and even temporary bundle-branch block might be observed. In this study, the authors measured arterial dP/dt_max, mean arterial pressure (MAP), and cardiac index using transpulmonary thermodilution, pulse contour analysis, and femoral artery catheter and compared the effects between right ventricular (A-RV) and biventricular (A-BiV) pacing on these parameters. Design: Prospective study. Setting: Single-center study. Participants: The study comprised 17 patients with a normal or prolonged QRS duration and a left ventricular ejection fraction ≤35% who underwent coronary artery bypass grafting with or without valve replacement. Interventions: Temporary pacing wires were placed on the right atrium and both ventricles. Different pacing modalities were used in a standardized order. Measurements and Main Results: A-BiV pacing compared with A-RV pacing demonstrated higher arterial dP/dt_max values (846 ± 646 mmHg/s v 800 ± 587 mmHg/s, p = 0.023) and higher MAP values (77 ± 19 mmHg v 71 ± 18 mmHg, p = 0.036). Conclusion: In patients with preoperative decreased left ventricular function undergoing coronary artery bypass grafting, A-BiV pacing improve the arterial dP/dt_max and MAP in patients with both normal and prolonged QRS duration compared with standard A-RV pacing. In addition, arterial dP/dt_max and MAP can be used to evaluate the effect of intraoperative pacing. In contrast to previous studies using more invasive techniques, transpulmonary thermodilution is easy to apply in the perioperative clinical setting.