ACUTE REGIONAL MYOCARDIAL-ISCHEMIA AND RECOVERY AFTER CARDIOPULMONARYBYPASS - EFFECTS OF INTENSITY OF ANTECEDENT ISCHEMIA

Aortic cross-clamping with inadequate myocardial preservation has been shown to cause postoperative decreases in myocardial performance foll owing coronary artery by-pass graft surgery. We have demonstrated a mi ld decrement in myocardial beta-receptor function associated with cold cardioplegia in a normal animal model; in normal human hearts, howeve r, response to beta-adrenergic inotropic stimulation was diminished si gnificantly. Beta-receptor dysfunction also is associated with chronic myocardial ischemia that is associated with severe ischemic heart dis ease. Although the change in beta-receptor function with acute regiona l myocardial ischemia associated with severe ischemic heart disease is not understood fully, we found that the intensity of regional ischemi a significantly affects functional recovery after cardiopulmonary bypa ss (CPB). Myocardial stunning does not appear to be significant in thi s dysfunction; however, alterations in beta-receptor density and funct ion may play a critical role in post-CPB ventricular function.