Myocardial Protection During Cardiac Surgery

In recent years there have been important advances in understanding causes of myocardial injury during cardiac surgery, in the introduction of mea­ sures to minimize this injury, and in improving the conditions for perform­ ing the surgery itself. Coronary artery surgery has been a major stimulus for this advance, since the flaccid and still myocardium provided by cold cardioplegic arrest greatly facilitates the performance of small-vessel anas­ tomoses. Since 1970, surgery for coronary artery disease has grown from several thousand procedures per year to more than 100,000 operations in 1980 (1). The improvement in operative technique for coronary artery bypass and the very low risk now associated with such procedures is in large part due to improved myocardial preservation. During the first decade of open heart surgery, which began in 1955, postoperative low cardiac output was usually believed to be secondary to the preoperative condition of the patient. However, by 1970 three observa­ tions were accepted: (a) inadequate myocardial protection during surgery was implicated as a major cause of postoperative low cardiac output and death (2); (b) inadequate myocardial protection was associated with the late development of myopathy, even after successful value replacement or repair of congenital defects (3, 4); and (c) a rare and extreme form of intraopera­ tive damage, stoneheart, was recognized to be secondary to poor intraop­ erative myocardial protection of severely hypertrophied hearts (5). These observations clearly reflected the need for substantial improvement in myo­ cardial protection in use at that time.