Thrombolysis for experimental deep venous thrombosis maintains valvular competence and vasoreactivity

Purpose: Thrombolysis protects the structural and functional integrity of v ein wall in an experimental model of acute deep venous thrombosis (DVT) imm ediately after treatment, but late sequelae have not been studied. We desig ned experiments to compare the effects of thrombolysis and surgical thrombe ctomy at 4 weeks after the treatment of DVT. Methods: DVT was produced bilaterally in male mongrel dogs by proximal and distal femoral vein ligation. Five dogs underwent sham operation. After 48 hours, the ligatures were removed, and the thrombosis was treated with eith er Fogarty balloon catheter thrombectomy (shear force, 60 g; n = 6) or cath eter-directed urokinase infusion (4000 U/min for 90 minutes; n = 6). At 4 w eeks, patency and valvular competence were determined by duplex ultrasound scanning. Thrombogenicity was studied by the measurement of radiolabeled fi brin and platelet deposition. Veins were explanted and prepared for histolo gic examination, scanning electron microscopy, and functional studies in or gan chambers. Results: ALL veins were patent at 1 month. Recanalized thrombus was observe d histologically in four (66%) thrombectomized veins, one (17%) thrombolyze d vein, and none of the sham-operated veins (P = .04). Scanning electron mi croscopy demonstrated similar luminal endothelial cell loss (11%-25%) in al l three groups. Platelet and fibrin depositions were not different among gr oups. Valvular incompetence (reflux duration, 20.5 sec) did nor differ sign ificantly in the groups (thrombectomized veins, 2 of 12 (17%); thrombolyzed veins, 0 of 12 (0%); P = NS). In organ chamber studies, endothelium-depend ent relaxations to calcium ionophore, but not adenosine diphosphate, were i nhibited by an antagonist of nitric oxide production after thrombectomy (P < .05, thrombectomy vs sham- and thrombolysis-treated veins). All veins rel axed to exogenous nitric oxide. Conclusion: Both thrombectomy and thrombolysis restored patency and achieve d similar valvular competence. Surgical thrombectomy, however, resulted in more residual thrombus and contributed to changes in endothelium-mediated r elaxations at 4 weeks. Thrombolysis maintained both structural integrity an d endothelial function.