The Impact of Limited Biventricular Stimulation on Cardiac Hemodynamics in Patients with Reduced Left Ventricular Function

Background: Patients with severely impaired left ventricular (LV) function often demonstrate prolonged inter- and intraventricular conduction. This prospective study investigates hemodynamic effects and outcomes of perioperative temporary biventricular pacing in patients with heart failure undergoing heart surgery. Methods: 100 consecutive cardiac surgery patients with a LV ejection fraction below 35% received biventricular stimulation via temporary myocardial electrodes. Group 1 consisted of 50 patients with LV dilatation (mean-LVEDD 65±5 mm), group 2 of 50 patients with normal or slightly dilated LV (mean-LVEDD 52±4 mm). Results: Hemodynamic parameters were measured immediately, 6 and 24 hours after operation. An increase of cardiac index (CI) and arterial blood pressure with biventricular pacing was observed in 27 patients (group 1/67.5%) versus 22 patients (group 2/55%) from 2.4±0.7 l/min/m2 to 3.5±0.5 l/min/m2 (p<0.01). This benefit persisted 6 and 24 hours postoperatively. The remaining patients already showed higher cardiac index prior to pacing (3.7±0.9 l/min/m2). In-group 1, responding patients required shorter times for ventilation support and intensive care. QRS duration before surgery was not predictive for the response to biventricular pacing. Conclusions: In the majority of patients with reduced LV function, temporary biventricular pacing improves CO and arterial blood pressure after surgery, especially when LV-dilatation is present.