Role of thrombolysis in peripheral arterial occlusion

In an initial study, 85 patients with 93 thromboembolic occlusions of peripheral arteries or grafts were treated with urokinase by direct intra-arterial infusion. Urokinase was infused directly into the proximal portion of the clot at 4,000 IU/minute for two hours. Arteriography was then repeated. If a channel had been lysed in the proximal part of the clot, but the distal part remained occluded, the catheter was gently advanced into the still occluded portion of the clot and the infusion was resumed at 4,000 IU/minute until antegrade blood flow was reestablished. Then the catheter was repositioned to be proximal to all of the remaining clot. The urokinase dosage was reduced to 1,000 IU/minute and the infusion continued with reexaminations at eight-hour intervals. The infusion was continued until complete clot lysis was accomplished. A search for a flow-limiting lesion on which to perform a percutaneous transluminal angioplasty was then performed. The lack of at least a 10 percent reduction in clot length after a 500,000-IU cumulative infusion dose of urokinase was an indication for termination of the regimen. Seventy-five percent of the 93 infusions resulted in complete clot lysis, even though in nine patients (10 percent) the infusion could not be completed. Eighty-one percent of the 84 completed infusions resulted in complete clot lysis, and the incidence of clinical improvement was 89 percent. The average duration of infusion was 18 hours. Major bleeding (requiring transfusion) occurred in only 4 percent of the patients. This regimen has now been applied to 150 occlusions, and the results are approximately the same. Review of our experience demonstrated that the ability to easily advance an angiographic guide wire through an occlusion has been the best predictor that a given clot would lyse irrespective of the clot's location or the duration of symptoms. Easy guide wire traversal appears to rule out the presence of either advanced changes of clot organization throughout the occlusion or a rare completely obstructing atherosclerotic lesion. A review of the published experience of 155 direct intra-thrombus infusions of 5,000 IU/hour of streptokinase demonstrated only a 45 percent incidence of complete clot lysis. Also, infusion times were quite prolonged (41 hours), and major bleeding complications were surprisingly common (13 percent). The results with urokinase thus indicate that it is preferable to streptokinase since it produces fewer complications and accomplishes more rapid recanalization and a higher incidence of total clot lysis.