Cardioplegia Solution

Abstract

The mechanisms of the metabolic and ultrastructural changes that occur as a result of myocardial ischemia during cross-clamping of the aorta and the secondary injury that can occur during reperfusion after removal of the cross-clamp are important determinants of the composition and method of administration of cardioplegia solution (CS). Traditionally, basic principles of myocardial protection included hypothermia, potassium-induced diastolic cardiac arrest, buffering, membrane stabilization, and control of osmolarity and osmotic pressure. As the mechanisms of myocardial ischemia and reperfusion are further shown, methods of providing myocardial protection continue to expand. Current trends favor blood cardioplegia administration via a more complex approach to protect as much of the myocardium as possible; exogenous metabolic substrate enhancement in the presence of oxygen to allow aerobic metabolism to continue, with an end result of additional available myocardial energy; and warm (37°C) blood CS to optimize the metabolic rate for cellular repair. Thus, today the cardiothoracic surgeon can offer patients with energy-depleted hearts and those requiring more complex surgery improved myocardial protection with active myocardial resuscitation before and after the aortic cross-clamp is placed and removed. To this end, the pharmacist, ideally an operating room (OR) pharmacist, has a vital role in ensuring proper preparation, composition, storage, and quality control/assurance of CS. The basic principles of myocardial ischemic and reperfusion injury and how they relate to myocardial protection, CS composition, and methods of administration are described. By understanding these principles, in addition to surgeon and institution-specific factors, the pharmacist can build the foundation needed to maximize the role of pharmacy in ensuring optimal myocardial protection during open-heart surgery.