Impact of off-pump coronary artery surgery on myocardial performance and β-adrenoceptor function

Objective: To determine the hemodynamic changes during beating heart revascularization of the left anterior descending artery, the circumflex artery, and the right coronary artery as well as cardiovascular beta -adrenoceptor function before and after off-pump coronary artery bypass surgery. Design: Prospective study. Setting: University department of cardiothoracic anesthesia. Participants: Twenty patients scheduled for off-pump coronary artery bypass surgery using the Octopus 2 stabilizer system. Interventions: Isoproterenol, 4 mug, was administered intravenously after induction of anesthesia and again after surgery to monitor cardiac beta -receptor function. Measurements and Main Results: The hemodynamic responses to isoproterenol and cardiovascular variables were monitored before, during, and after immobilization of the target coronary artery with catheters in the radial and pulmonary arteries. During surgery on the left anterior descending artery (n = 23), stroke volume and cardiac index decreased 17 mL (21%) and 400 mL (17%). During revascularization of the circumflex artery (n = 9), stroke volume and cardiac index decreased 19 mL (28%) and 300 mL (17%). During surgery on the posterior aspect of the heart (n = 13), stroke volume and cardiac index decreased 22 mL (29%) and 400 mL (17%). All the cardiovascular variables had returned to baseline values 5 minutes after releasing the heart. The hemodynamic responses to isoproterenol were equal before and after surgery. Conclusion: This study provides evidence that the hemodynamic changes associated with off-pump surgery on the 3 major coronary arteries are similar and of short duration. No desensitization of cardiovascular beta -adrenoceptors was found. This finding is in contrast to the deterioration in beta -adrenoceptor function seen after surgery with cardiopulmonary bypass. Copyright (C) 2001 by W.B. Saunders Company.