FIBRINOLYTIC RESPONSE AFTER VENOUS OCCLUSION AND DDAVP IN PATIENTS WITH DEEP VENOUS THROMBOSIS

Abstract

After prolonged stimulation venous endothelium becomes refractory to otherwise efficacious stimuli for tissue plasminogen activator (t-PA) release. When the stimulus is removed, the restitution of the response is observed. The distention of the veins distally from the occlusion site in deep venous thrombosis (DVT) could represent such a chronic stimulus. We studied t-PA release in patients with DVT during 20-min venous occlusion (VO) and DDAVP infusion (0,4 ug/kg b.w. in 10 min). t-PA release was estimated as the difference in euglobulin clot lysis time (ECLT in U) and fibrin plates (FP in mm2) before and after VO (fibrinolytic potential). Two groups of patients were studied: 15 recumbent patients with oneside iliofemoral DVT, and 15 patients with oneside postthrombotic syndrome.In both groups the response of legs was lower than that of arms. The comparison of the healthy and the affected leg in postthrombotic group showed no difference in t-PA release after VO. A higher release of t-PA was seen in the acute DVT group in all three tested limbs, explainable by a restitution of fibrinolytic potential due to the reduction of hydrostatic stimulus. However, the response was slightly lower in the diseased leg. In 5 patients from the acute DVT group DDAVP infusion induced higher t-PA release after VO in both legs compared to VO before DDAVP. We can conclude that hydrostatic pressure in upright position is such a strong stimulus that an additional decrease of t-PA release due to chronic venous stasis cannot be expressed. In recumbent patients DVT hinders the restitution of the response to V0 in the diseased leg. DDAVP seems to act independently of hydrostatic pressure and venous stasis.