Current Hematologic Issues in Cardiac Surgery and Cardiopulmonary Bypass

Recently, new attempts have been made to fight old problems of coagulation and hemostasis as they relate to cardiac surgery. These discoveries are timely because the practice of both internists and surgeons has begun to change. Newer and more potent medications are being used by cardiologists in an effort to exert better control over hemostatic mechanisms with the hope that this may eventually improve the chances for sur vival of patients with coronary artery disease. In addi tion, cardiac surgeons have been more aggressive in voicing their concerns that cardiopulmonary bypass (CPB) is nothing more than a necessary evil. More and more surgeons are performing coronary artery bypass surgery (CABG) without the use of a CPB machine when possible. Cardiac anesthesiologists are expected to take patients from the emergency room (where they may have received thrombolytics), from the catheterization laboratory (where they may have received antiplatelet agents), and from the intensive care unit (where they may have received heparin) to the operating room, where they will undergo further anticoagulation therapy and then have their blood exposed to a thrombogenic surface for up to several hours. It is even more impor tant to ensure that this is all reversed at the end of surgery. The answers to these problems are not entirely available yet; however, one piece of the puzzle has been found. What follows is a review of hemostatic balance in patients who present for cardiac surgery and how this relates to thrombin, the center of the coagulation universe. It is believed that by better control of the generation of thrombin during CPB, patients may have better results from anticoagulation therapy during sur gery and have fewer problems with bleeding after surgery. A discussion on the newest attempt at this, antithrombin III, follows.