Treatment of thrombotic saphenous vein bypass grafts using local urokinase infusion therapy with the Dispatch catheter.

Percutaneous treatment of thrombotic stenoses or total occlusions in aged saphenous vein bypass grafts is associated with a significant incidence of complications primarily related to distal embolization. The purpose of this study was to assess the efficacy of local urokinase delivery with the Dispatch catheter prior to balloon angioplasty and/or intragraft stent placement as a new technique of vein graft revascularization. Local urokinase delivery with the Dispatch catheter was performed in 15 saphenous vein grafts (mean age = 11.7 +/- 2.5 yr) in 13 patients with unstable or postinfarction angina. The target lesion was a total occlusion in 5 of the procedures and a severe vein graft stenosis in the remaining 10. In all cases, urokinase was administered directly to the site of the stenosis/occlusion via the Dispatch catheter at 0.5 cc/min and at a concentration of 30,000 units/cc. The mean urokinase infusion time for the 15 procedures was 33 +/- 10 min (range = 10-60 min) and the mean urokinase dose was 495,000 +/- 158,000 units (range = 150,000-900,000 units). Following Dispatch therapy, mean minimal lumen diameter increased from 0.34 +/- 0.32 to 1.81 +/- 0.78 mm (P < 0.01), mean TIMI flow increased from 1.9 +/- 1.4 to 2.8 +/- 0.8 (P < 0.06), and mean thrombus score was reduced from 2.3 +/- 0.6 to 0.3 +/- 0.8 (P < 0.01). Mild no reflow was noted in two cases, although no patient demonstrated angiographic evidence of gross distal embolization. One of the patients with no reflow also demonstrated a small increase in cardiac enzymes. Subsequent balloon angioplasty/stent placement was successful in 14 of the 15 procedures (93% success rate). This preliminary report suggests that pretreatment of thrombotic saphenous vein graft stenoses with local urokinase delivery via the Dispatch catheter may decrease intragraft thrombus and possibly decrease the incidence of vascular complications associated with percutaneous intervention. This technique may allow for recanalization of totally occluded vein grafts with large clot burdens by using significantly less urokinase and shorter drug administration times than conventional infusion protocols.