Abstract
The fibrinolytic activity was examined before and after intracoronary thrombolysis with urokinase in 11 patients with acute myocardial infarction. Urokinase was administered as a solution of 24×104IU in 20ml into the obstructed coronary artery and this therapy was repeated till recanalization was achieved or maximum dose of 96×104IU was reached. In two cases the dose of urokinase was increased to 120×104IU and in another case to 144×104IU; in this patient cardiac rupture occurred 9 hours after the procedure (Table 1). The mean dose of urokinase administered was 103×104IU. Fibrinolytic activity was determined every 8 hours for 24 hours and at 48 hours after intracoronary thrombolysis.
The result of intracoronary thrombolysis was observed in 8 of the 11 patients; recanalization was achieved in 75% (6 patients) (Table 1).
The fibrinolytic activity before and after intracoronary thrombolysis is summarized in Table 2. Euglobulin lysis time and the fibrinolytic activity of euglobulin fraction by fibrin plate method showed markedly increased fibrinolytic activity soon after urokinase administration (Figures 1, 2).
Plasminogen, fibrinogen and α2-plasmin inhibitor were decreased markedly (Figures 3, 4, 6), and fibrin or fibrinogen degradation products (FDP) were increased after urokinase administration (Figure 5). α2-Macroglobulin decreased gradually to the steady state level of 83% of the control value after 16 hours, α1-Antitrypsin was rather, increased significantly 48 hours after intracoronary thrombolysis (Figure 8).
In conclusion, the decrease in α2-plasmin inhibitor, plasminogen or fibrinogen may indicate enhanced fibrinolytic activity, though they are not direct indicators. α1-Antitrypsin may not act as an anti-plasmin in vivo, although it has been thought to be an anti-plasmin. The dose of 103×104IU of urokinase seems to be sufficient to activate fibrinolysis, because plasminogen, fibrinogen and α2-plasmin inhibitor decreased and FDP increased markedly and significantly after the administration of this amount of urokinase. Intracoronary thrombolysis with simultaneous measurement of fibrinolytic activity in vitro is a good way to evaluate laboratory measurements of fibrinolytic activity, because the changes in the intracoronary thrombus during the administration of urokinase can be seen directly by coronary arteriogaphy.
