Intravascular Stent Deployment Across Vein Graft Anastomoses: Acute and Chronic Results

Abstract

Anastomotic stenosis continues to be an important cause of late graft failure. Intravascular stents may allow the dilatation of these hyperplastic lesions, thereby increasing secondary graft patency rates. To study the acute and chronic effects of intravascular stent deployment across vein graft anastomoses, we implanted balloon expandable stents in 26 femoral venous bypass grafts in 13 sheep. Six weeks after graft construction, intravascular stents (17 slotted, 9 coiled) were deployed across each anastomosis. The stented vein grafts were then harvested immediately or at 3 weeks, 8 weeks, and 6 months postdeployment, with arteriograms obtained and stented segments processed for scanning electron microscopy. Total stent patency was 92%; 88% (15/17) slotted, 100% (9/9) coiled. One slotted stent remained patent despite the presence of chronic thrombus, and distal migration occurred in 33% of coiled stents. Extrinsic compression caused stenoses in 2 stents although both remained patent. Slotted stents exhibited greater endothelialization than coiled stents at 3 and 8 weeks while both were completely covered at 6 months. Stent-vessel wall contact averted thrombosis, migration, and delayed endothelialization. We conclude that stents across vein graft anastomoses demonstrate excellent patency with complete endothelial coverage and minimal intimai proliferation. Stent-vessel wall contact is a critical factor for successful deployment.