Establishment of an experimental intracranial internal carotid artery model and the application in covered-stent navigability testing

BACKGROUND AND PURPOSE: The carotid siphon is a natural barrier to intracranial interventions. Our aim was to make a model of the human intracranial internal carotid artery (ICA) and to test the navigability of covered stents for intracranial applications. MATERIALS AND METHODS: A digital tube was made on the basis of raw MR images of the human ICA. It was transferred into 10 physical models and then coated with silicone by using a 3D rapid prototyping (RP) machine. Ten dogs then underwent surgery. Their common carotid arteries (CCAs) were exposed, cut, and passed through 1 of the tubes. Finally, the vascular models were made by reanastomosis of their CCAs. Eight expended polytetrafluoroethylene (e-PTFE) covered stents (two 3.5 × 16 mm, two 3.5 × 13 mm, two 3.5 × 10 mm, and two 3.5 × 7 mm) were implanted 1 week later. Two dogs remained as controls. The performance of the device was evaluated by angiography and histopathologic examination. RESULTS: Ten animal models were successfully constructed. There was no vascular spasm or thrombosis when assessed by angiography. Destruction of the tunica intima and media was found in the 3.5 × 16 mm stent group. Destruction of the endothelium was found in the 3.5 × 13 mm stent group, and only flattening of the endothelium was found in the 3.5 × 10 mm and 3.5 × 7 mm stent groups. CONCLUSIONS: The experimental model was thought to simulate adequately the geometry of the human ICA and, thus, would be an effective tool for the research and testing of neurovascular devices. The length of the stent is 1 factor influencing the navigability in tortuous vessels.