The Effects of Thrombus, Thrombectomy and Thrombolysis on Endothelial Function

AbstractObjective: this study was undertaken to examine and compare the effects of thrombus, thrombectomy, and thrombolysis on endothelial function as measured by endothelium-dependent vasorelaxation (EDR). Methods: adult, male New Zealand white rabbits underwent ligation of the left common iliac to femoral artery to induce thrombosis and were then randomly assigned to one of five groups, n=6 in each. Group A consisted of ligation and thrombosis for 4 h. Group B underwent similar ligation for 4 h, but without intraluminal thrombus present. Following 4 h of ligation and thrombosis, Group C underwent thrombectomy while group D was treated with urokinase (UK), 4000 U/min for 30 min. Group E underwent UK infusion alone. The right external iliac artery served as control vessel in each group. All arteries were removed and endothelial function was determined by measuring EDR. Results: the presence of thrombus reduced EDR by 50% (group A) compared to control. Vessels with interrupted flow, but not exposed to thrombus, retained normal EDR (group B). Thrombectomy decreased EDR significantly (group C) compared to thrombolysis (group D) and control. UK did not significantly alter EDR (groups D, E).Conclusions: exposure of endothelium to thrombus significantly decreases EDR. EDR was not affected by interruption of blood flow in the absence of thrombus. Thrombectomy appeared to cause a further additive insult to the endothelium. In contrast, thrombolysis with UK preserved residual endothelial function. These data suggest that it is important to differentiate the effects of thrombus on endothelium from effects due to thrombectomy or thrombolysis when evaluating treatment modalities for arterial thrombosis