Intimal hyperplasia following thrombectomy versus thrombolysis in occluded vein grafts

Although the histologic effects of balloon catheter thromboembolectomy in arteries are well described, little is known about its effects on arterialized vein grafts. A chronic canine model was used to compare the intimal hyperplasia that develops following balloon catheter thrombectomy versus thrombolytic therapy when each treatment was used to open experimentally occluded reversed autogenous vein grafts. Eleven of 12 dogs survived to the time of graft thrombosis and treatment. Ten grafts in one group of animals were treated with shear force-controlled balloon catheter thrombectomy, and eleven grafts in another group of animals were treated with infusion of urokinase (average 355, 833 IU/graft). Explantation and histologic evaluation was performed 5 weeks after treatment. Data were evaluated at comparable anatomic locations. These studies demonstrated the development of intimal hyperplasia in both groups with no statistically significant differences in the intimal thickening between the two treatment groups. It is hypothesized that vessel wall damage occurs at the time of thrombosis with the adherence of thrombus to the wall, and that this may be as important in producing intimal hyperplasia as the effects of carefully performed balloon thrombectomy or lytic therapy.