Therapy of acute myocardial infarction in the 1990s

Postoperative changes in coagulant and anticoagulant factors following abdominal aortic surgery

The extent and time course of changes in selected procoagulant and anticoagulant factors were investigated in 19 patients undergoing elective abdominal aortic surgery. The coagulation factors were measured preoperatively, and on days two, four, and six postoperatively. It was found that there were no significant changes outside the normal range in prothrombin time, partial thromboplastin time, or thrombin clotting time. However, there were large increases in the procoagulants, fibrinogen, factor VIII coagulant, factor VIIIRag/von Willebrand factor, and in alpha 1-antitrypsin. Over the same time there were marked decreases in the naturally occurring anticoagulants, protein C and antithrombin III, and in alpha 2-macroglobulin. These changes implied that the patients were "hypercoagulable" in the postoperative period. The maximum changes in the procoagulants occurred on either postoperative day two or day four. The maximum changes in the natural anticoagulants occurred on postoperative day two. There were no significant changes in factor V, factor X, alpha 2-antiplasmin, or platelet aggregability. The timing of the changes coincided with a period of high risk of perioperative myocardial infarction in this group of patients. Thus, it is possible that postoperative hypercoagulability contributes to the development of coronary artery thrombosis and myocardial infarction following abdominal aortic surgery.

Fibrinolytic effects of pro-urokinase combined with low-dose urokinase compared to high-dose urokinase in patients with acute myocardial infarction

20 patients (6 females, 14 males) aged between 47 and and 75 years (mean: 62.6 yrs.) with acute myocardial infarction (onset of symptoms within 6 hours) were treated intravenously with either 200,000 U urokinase (UK) and 4.5 million U pro-urokinase (pro-UK) within 60 min (group I, N = 10), or 2.5 million U UK within 5 min (group II, N = 10). Blood samples for haemostatic and fibrinolytic function tests were taken prior to and repeatedly during the 24 hours following treatment. Peak fibrinolytic activity measured by fibrin plates was equivalent in both regimens. Average decreases, with lowest levels within 60 to 120 min following thrombolytic therapy, were observed of 27% and 70% for plasminogen, of 71% and 91% for alpha-2-antiplasmin, and of 20% and 74% for fibrinogen in group I and II, respectively. The reptilase time reached maximum values of 1.5- and 4.5-fold within 60 to 180 min. Peak levels of D-dimers and thrombin-antithrombin III complexes in group II were 2.6 and 3.2 times those of group I. After 24 hours, in contrast to group I, all these parameters still remained significantly different from pretreatment values in group II. These data indicate that, contrary to high-dose UK, pro-UK in combination with low-dose UK causes minor systemic fibrinolytic effects and is, therefore, assumed to be largely clot-specific, although the fibrinolytic potential is equivalent for both regimens.