Cardiac enzymes and autotransfusion of shed mediastinal blood after myocardial revascularization

Background. Autotransfusion of shed mediastinal blood reduces blood requirement after coronary artery bypass grafting. Recently, two nonrandomized trials indicated that autotransfusion elevates the levels of cardiac enzymes after cardiac operations. Methods. Prospective, randomized controlled studies involving 120 patients (study A) and 15 patients (study B) having elective uncomplicated coronary artery bypass grafting were performed. Autotransfusion of shed medioastinal blood was performed for 18 hours in the patients allocated to autotransfusion. Serum levels of cardiac enzymes were measured. In study B cardiac enzyme levels in shed mediastinal blood and circulating blood were measured 1 hour postoperatively. Results. Cardiac enzyme levels were significantly elevated in the patients receiving autotransfusion. In patients with a perioperative myocardial infarction the level of creatine kinase-MB was much higher than in the autotransfused patients without myocardial infarction. The level of cardiac enzymes was higher in shed mediastinal blood compared with circulating blood. Conclusions. Postoperative autotransfusion of shed mediastinal blood causes elevation of cardiac enzyme levels after coronary artery bypass grafting.