Improved efficacy of intra-aortic balloon pumping by pharmacological myocardial protection for postoperative pump failure after coronary revascularization

Protect the heart in the intensive care unit--but how?

The heart plays a pivotal role in determining the oxygen supply to the body. As a result of its high oxygen extraction ratio, the myocardium must function efficiently to supply itself with oxygen. In the context of the ICU, the efficient functioning of the myocardium is confounded by a number of pathologic processes that may interfere with its oxygen supply or increase its oxygen demand. Conventional drug treatment of acute myocardial decompensation tends to increase myocardial oxygen demand. The myocardium may potentially be "protected" by treatment modalities that favorably alter the oxygen supply to demand ratio. Newer methods of protecting the heart may involve improving the coordination of myocardial contraction, using novel inotropic agents, supporting the myocardium metabolically, administrating blood products more conservatively, favorably altering the immune response, and using mechanical support devices. Myocardial protection may be improved by better use and understanding of monitors of myocardial performance.

Preventing the inflammatory response to open-heart surgery: the role of aprotinin and other protease inhibitors

This review discusses the role of protease inhibition in reducing or preventing certain of the deleterious effects of major surgery. The ability of agents such as aprotinin to inhibit bleeding and reduce the need for donor blood transfusions is now well established. What is less well recognized is that aprotinin is not simply an antifibrinolytic but is a polyvalent enzyme inhibitor of many of the enzymes which are involved in inflammatory and hemostatic processes. Inappropriate activation of these pathways is considered to be important in the genesis of the inflammatory response to open-heart surgery. The first part of the article reviews aspects of the inflammatory and hemostatic systems which have a common basis and which utilize proteolytic actions for their control. In the later part of the review, the effect of a period of cardiopulmonary bypass on organ and tissues is discussed together with the effects of protease inhibition to prevent any abnormal or inappropriate response to the stimulus. Consideration of these aspects will hopefully allow a more rational and scientific approach to the uses, possible benefits and perceived or real safety issues following administration of these agents.

Lower cardiac troponin T levels in patients undergoing cardiopulmonary bypass and receiving high-dose aprotinin therapy indicate reduction of perioperative myocardial damage

Nowadays in many European heart centers the activation of the fibrinolytic system, always occurring during cardiopulmonary bypass, is routinely reduced by high-dose application of the proteinase inhibitor aprotinin (total of > 4 million KIU). In this study parameters of myocardial ischemic injury were investigated with the aim of identifying further benefits of aprotinin, particularly the protection of the myocardium during the ischemic period of aortic crossclamping. Forty patients with coronary artery disease who underwent aorta-coronary bypass grafting were randomly and in a double-blind fashion divided into two groups, one that received high-dose aprotinin therapy and one that received only saline solution. Markers such as troponin T, with high specificity for detection of myocardial ischemia and infarction, and markers with more general specificity such as creatine kinase, its isoenzyme, and lactate dehydrogenase showed significantly increased values after ischemia in both groups. In patients who received high-dose aprotinin therapy 3 days after cardiopulmonary bypass all parameters measured showed significantly lower levels compared with those in the control group. Therefore we can presume that the application of high-dose aprotinin provides myocardial protection from perioperative ischemic injury.

Aprotinin therapy for reoperative myocardial revascularization: a placebo-controlled study

We tested the efficacy and safety of aprotinin in 169 patients undergoing isolated reoperative myocardial revascularization. Patients were randomly assigned to high-dose aprotinin, low-dose aprotinin, or placebo treatment groups in a double-blind, placebo-controlled study. Treatment groups did not differ significantly with respect to age, sex, red cell mass, number of grafts, use of internal thoracic artery, or incidence of preoperative aspirin therapy. Patients treated with aprotinin had a significant reduction in postoperative chest tube drainage (720 +/- 753, 866 +/- 1,636, and 1,121 +/- 683 mL, respectively, for high-dose aprotinin, low-dose aprotinin, and placebo; p < 0.001). Transfusion requirements were reduced in aprotinin-treated patients (2.1 +/- 4.2, 4.8 +/- 11.8, and 4.1 +/- 6.2 units for high-dose, low-dose, and placebo, respectively; p < 0.001). A similar reduction in chest tube drainage and transfusion requirements was seen in patients using aspirin preoperatively. Q-wave myocardial infarctions were increased in the aprotinin subgroups (17.5%, 14.3%, and 8.9% for high-dose, low-dose, and placebo groups; not significant). Acute vein graft thrombosis was found in six of 12 vein grafts studied at postmortem examination in patients receiving aprotinin but not in any of five grafts in patients receiving placebo. We conclude that aprotinin is extremely effective in reducing bleeding and transfusion requirements and may increase the risk of graft thrombosis.