Aprotinin: the ideal anti-coagulant?

The serine proteinase inhibitor, aprotinin, significantly reduces transfusion requirements during open heart surgery. Whether this benefit is associated with an increased tendency to thrombosis has not been studied. We investigated the effect of aprotinin in an experimental arterial thrombosis model. In 17 male Sprague-Dawley rats, the infrarenal aorta was replaced with 1.0-mm diameter PTFE grafts of varying lengths. The time to graft occlusion, recorded by palpation, Doppler ultrasound and a distal bleeding test, was 20.2 +/- 1.8 min, 35.8 +/- 6.1 min and 43.7 +/- 6.6 min for grafts of 10, 7.5 and 5.0 mm respectively (r = -0.98, p less than 0.05). Following PTFE graft placement 24 Sprague-Dawley rats were given saline (n = 6), aprotinin (n = 6), heparin (n = 6), and heparin + aprotinin (n = 6). The time to occlusion was significantly prolonged in the aprotinin group (71.7 +/- 20.4 min vs. 20.2 +/- 1.8 min, p less than 0.05). The time to thrombosis for heparin + aprotinin and heparin alone was also significantly prolonged (p less than 0.05). Prothrombin times (PT) were 21.9 +/- 3.0 s for control, 29.4 +/- 6.2 s for aprotinin, 40.7 +/- 2.5 s for heparin and 39.9 +/- 14.5 s for heparin + aprotinin (p less than 0.05 vs. control for all values). Bleeding time was not prolonged with aprotinin (3.0 +/- 0.9 min vs. 2.9 +/- 0.7 min). The bleeding time was 18.9 +/- 4.1 min for heparin + aprotinin and 22.5 +/- 2.3 min for heparin alone (p less than 0.05 vs. control for both values).(ABSTRACT TRUNCATED AT 250 WORDS)