[Thrombus age as a determinant of lysis efficacy of in vitro produced platelet-fibrin thrombi].

Thrombus age as a determinant of lysis efficacy has rarely been investigated. We developed an in vitro model to study the lysis of collagen induced platelet-fibrin-thrombi of different ages. Histologically, the thrombi were similar to those found in coronary vessels of patients deceased from acute myocardial infarction or unstable angina. After 10 (TA10), 30(TA30) und 60 (TA60) min of thrombus aging thrombolysis over 30 min with urokinase alone or in combination with prostaglandin E1 was started. The efficacy of lysis with urokinase alone decreased with increasing thrombus age. After 30 min of lysis with urokinase alone weight of TA10-thrombi was reduced by 16.4 +/- 1.2 mg, of TA30-thrombi by 11.5 +/- 0.9 mg (p < 0.001 vs TA10-thrombi) and of TA60-thrombi by 7.8 +/- 1.1 mg (p < 0.001 vs TA30, p < 0.0001 vs TA10-thrombi). The addition of prostaglandin Ei augmented lysis of TA10-thrombi, after 30 min of lysis thrombus weight was reduced by 17.3 +/- 1.2 mg (p < 0.01 vs urokinase alone). Lysis of 30 and 60 min old thrombi was nearly unaffected. Thus, thrombus age is a strong predictor of lysis efficacy of in vitro collagen induced platelet-fibrin-thrombi.