[Pit fall of aprotinin administration during open heart surgery]

Aprotinin administration during open heart surgery has been attempted at various institutions to reduce hemorrhage and improve the rate of no-transfusion operations, and has been reported to be effective. The treatment has been effective also in the 45 patients operated on at our institution. However, we experienced LOS at weaning from extracorporeal circulation (8 cases) considered to be due to aprotinin administration, suggesting unexpected risk of the treatment. Evaluation was made by classifying the patients according to the aprotinin dose; A high-dose group administered aprotinin at 300 x 10(4) units (20 patients), a low-dose group administered aprotinin at 100 x 10(4) units (8 patients), and a control group not administered aprotinin (15 patients). The volume of postoperative hemorrhage increased with the dose of aprotinin, and was significantly lower in the high dose and medium-dose groups than in the control group, but was not significantly different in the low-dose group. The postoperative peak CPK and CPK-MB were not significantly differ but increased slightly with the aprotinin dose. Probably for this reason, IABP was needed in 8 (17.8%) of the 45 patients because of LOS at weaning from extracorporeal circuration. A diagnosis of perioperative myocardial infarction (PMI) was made in 7 of these patients. Factors other than aprotinin are unlikely to be the cause of LOS, and the condition is considered to have been induced by micro-embolism during extracorporeal circulation with aprotinin administration. We propose two points as basis for this speculation. The first is that the body temperature during extracorporeal circuration, which was 30-35 degrees C in the bladder, promoted antifibrinolytic activity of aprotinin. The second is poor control of ACT during extra corporeal circulation. Thus, we suggest the risk of the use of aprotinin without further reduction in the body temperature during extracorporeal circuration. At present avoidance of high body temperatures and strict control of ACT during extracorporeal circulation are important preventive measures against micro-embolism possibly caused by aprotinin.