Myocardial protection for cardiac surgery: Classical views and new trends

Although research in myocardial protection has been one of the most prolifi c fields in medical research, little progress has been achieved in prolongi ng the safe cardiac ischemic time. In the early days of cardiac surgery, my ocardial protection as such did not exist. Most procedures were performed b y relying on speed and hypothermia. Later on, aortic cross-clamp and ventri cular fibrillation associated with mild hypothermia were widely used for co ronary bypass grafting surgery. The safe duration of ischemia was obviously very short and most intracardiac procedures could not be performed. The development of cardioplegia has been the major breakthrough in myocardi al protection. In the early 1980s, intervention during reperfusion develope d to further improve the postischemic cardiac recovery. More recently, it became clear that stimulation of endogenous mechanisms of protection, namely heat stress protein and ischemic preconditioning, could be used as a means of protection. Endogenous mechanisms of protection are particularly attractive in that they refer to the possibility of acting bef ore the very onset of ischemia. The field of cardiac surgery is undergoing significant changes that could r equire more refined and advanced methods of protection. The patient populat ion is getting older, and the number of patients with poor ventricular func tion is increasing. Furthermore, some changes in the surgical technique suc h as warm surgery and beating heart surgery are questioning the very basic principles of myocardial protection. This chapter reviews the currently used methods of cardiac protection again st ischemia and the new trends and future direction of research in this ver y difficult field.