Opioids and Cardioprotection: The Impact of Morphine and Fentanyl on Recovery of Ventricular Function After Cardiopulmonary Bypass

Objectives: Experimental studies have shown that opioids protect the myocardium from ischemic injury and that opioid cardioprotection is enhanced by the coadministration of volatile anesthetics. Previous data suggest that morphine produces a more potent cardioprotective effect than fentanyl. The present study investigated the effect of the choice of intraoperative opioid (morphine or fentanyl) on recovery of myocardial function after coronary artery bypass graft (CABG) surgery. Design: Prospective, randomized study. Setting: University hospital. Participants: Forty-six patients undergoing CABG surgery. Interventions: Patients were randomly assigned to receive either morphine (40 mg) or fentanyl (1,000 μg) before cardiopulmonary bypass (CPB). Global cardiac function was assessed intraoperatively using the myocardial performance index (MPI), which combines echocardiographic parameters of both systolic and diastolic function. Measurements and Main Results: The MPI (median [range]) was increased after CPB in the fentanyl group, indicating a significant worsening of global left ventricular function (0.43 [0.28-0.54] baseline; 0.49 [0.32-0.64] 15 minutes post-CPB; 0.51 [0.36-0.63] end of operation; p < 0.05 post-CPB compared with baseline). The MPI improved in the morphine group after CPB (0.44 [0.32-0.64] baseline; 0.36 [0.24-0.45] 15 minutes post-CPB; 0.34 [0.20-0.46] end of operation; p < 0.05 post-CPB compared with baseline and the fentanyl group). Conclusions: In patients undergoing CPB, global ventricular function is enhanced by the administration of morphine prior to the ischemic insult of cardioplegic arrest.