Objective: To compare hemodynamics and oxygenation in patients with congestive heart failure and broad QRS complexes before and with biventricular DDD pacing and to report experience with this new procedure. Design: Prospective, observational study. Setting: Major university-affiliated community hospital. Participants: Ten patients with congestive heart failure (New York Heart Association III to IV) and broad QRS complexes (>160 msec). Interventions: Patients underwent implantation of a biventricular pacemaker (n = 4) or implantation of a combined biventricular pacemaker and cardioverter-defibrillator (n = 6). Anesthesia was performed using remifentanil (0.2 to 0.3 μg/kg/min) and propofol. Propofol was used as target-controlled infusion (plasma target concentration, 1.5 to 2.5 μg/mL). Measurements and Main Results: Hemodynamics and oxygenation were measured before and with biventricular DDD pacing. Mean arterial pressure was significantly increased from 64.7 ± 5.8 mmHg to 77.8 ± 10.6 mmHg by biventricular pacing, whereas cardiac index (2.2 ± 0.3 L/min/m2 before and 2.3 ± 0.3 L/min/m2 with biventricular pacing) and pulmonary capillary wedge pressure (12.1 ± 3.8 mmHg before and 14.2 ± 3.6 mmHg with biventricular pacing) remained unchanged. Left ventricular stroke work index was increased >10% in 7 patients. Oxygen delivery, oxygen consumption, and difference in arteriovenous oxygen concentration were not affected. Anesthesia with remifentanil and propofol was safe and well-controllable and allowed immediate extubation at the end of the operation. Conclusion: There was no acute intraoperative improvement of hemodynamics except increased mean arterial pressure with biventricular pacing. Left ventricular performance seemed to improve with biventricular pacing in some patients. These results might be due to a nonoptimized atrioventricular delay. Postoperatively, atrioventricular delay was individually programmed for each patient by Doppler transmitral flow patterns.