• Jochen D Muehlschlegel, Yong G Peng, Emilio B Lobato, Philip J Hess, Tomas D Martin, and Charles T Klodell.
• Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
• J Card Surg. 2008 Jul 1;23(4):324-30.

Background And AimPatients with low ejection fraction (EF) undergoing myocardial revascularization frequently require ventricular pacing following cardiopulmonary bypass (CPB). While the benefits of chronic biventricular (BiV) pacing in patients with low EF are well established, there are little data on acute effects during heart surgery. This study analyzed the response of BiV versus single ventricle lead pacing on hemodynamics and left ventricular (LV) function immediately following CPB.MethodsTen patients with decreased LV EF (mean = 35 +/- 6%) underwent open-heart surgery with CPB. Temporary pacing electrodes were placed on the right atrium, apex of the right ventricle, and lateral wall of the LV after separation from CPB. The hemodynamic effects of three atrio-ventricular (right, left, and BiV) pacing modes were studied for four minutes each. The pacing sequence was randomly allocated with a resting period of three minutes between each mode. Hemodynamic and echocardiographic data of LV function were collected. Statistical analysis was performed with analysis of variance.ResultsBiV pacing increased cardiac output by 4%, 13%, and 44% over right ventricular pacing, LV pacing, and pre-bypass values, respectively. The fractional area of change increased significantly with BiV pacing compared to right ventricular and LV pacing (36%, 35% to 44%, p < 0.01). An increased propagation velocity of 49 cm/s compared to 38 cm/s and 40 cm/s for right ventricular and LV pacing, respectively, suggested an improvement in diastolic function.ConclusionIn patients with low EF, BiV pacing immediately after CPB significantly improves LV systolic function and cardiac output, and suggests significantly improved diastolic function.

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