An Endovascular Model of Carotid Stenosis for the Evaluation of Thrombolysis and Angioplasty

Abstract

Purpose: To develop a porcine carotid artery thrombosis model using a novel stent-graft device to evaluate the efficacy of thrombolytic therapy and angioplasty procedures. Methods: An endovascular device made from a tapered polytetrafluoroethylene graft inverted in a self-expanding nitinol stent was delivered to bilateral carotid arteries via a right femoral approach in 16 pigs. Carotid thrombotic occlusion ensued from flow stasis created by the intrastent stenosis. Via selective carotid catheterization from a femoral approach, urokinase (250,000 IU) was pulse-sprayed in one carotid artery while a control saline solution was infused in the contralateral vessel; delivery times were 1 hour, 8 hours, 3 days, or 6 days after carotid occlusion (4 animals per time period). After thrombolysis, balloon angioplasty was performed to maintain carotid patency. Arteriography and intravascular ultrasound were used to evaluate the efficacy of thrombolysis. Light microscopy was used for histological analysis of the thrombus. Results: Carotid artery occlusion occurred in 15 ± 8 minutes after stent-graft placement in all animals. Urokinase was effective in recanalizing all occluded arteries in the 1-hour, 4-hour, and 3-day groups (100%) but was effective in only 2 of 4 animals in the 6-day group (p < 0.05). Overall thrombolytic efficacy was 78% ± 7%. Control saline solution showed no thrombolytic effect (p < 0.001). Angioplasty successfully restored normal luminal diameter in all fully lysed arteries (100%). Histological analysis showed fibrin-predominant thrombus with a varying degree of platelet deposition. Conclusions: This endovascular approach, which creates a carotid stenosis using this novel stent-graft device, is reliable in producing carotid thrombosis. In our model, thrombolytic therapy was effective in restoring luminal patency, and the intraluminal stenosis is amenable to balloon angioplasty. The model is useful for the evaluation of antithrombotic therapy and adjunctive endovascular interventions.