A new experimental model of intracranial internal carotid artery and its application in testing the navigability of the covered stents

Objective: By using rapid prototyping technique to establish a vascular model in dogs with its twisting shape simulated to the human intracranial carotid artery (ICA) and by using this vascular model to test the navigability of the Willis covered stents. Methods: A cultivated digital tube was made based on the raw MR images of human ICA. Then the digital tube was transferred into a real physical model in a 3D rapid prototyping machine. Silicon was coated. The carotid arteries of canine were exposed and cut, and then the tube was put through and anatomized to get the vascular model. Eight e-PTFE covered stents (two each at size of 3.5 mm x 16 mm, 3.5 mm x 13 mm, 3.5 mm x 10 mm and 3.5 mm x 7 mm, Shanghai Microport Co. Ltd.) were implanted one week later. Two dogs were taken as control group. Device performance was evaluated by angiography and histopathological examination. Results: Ten animal models were successfully established. Neither vascular spasm nor thrombosis was seen on angiography. Destruction of tunica media was found in the group of 3.5 mm x 16 mm and destruction of endothelium in the group of 3.5 mm x 13 mm, while only flattening of the endothelium was noted in both groups of 3.5 mm x 10 mm and 3.5 mm x 7 mm. Conclusion: Simulating the three-dimensional anatomy of human ICA and providing an effective tool for the research and for the testing of neurovascular devices, this experimental vascular model can be easily established and the procedure is of high controllability, repeatability and factuality. It is also a useful devise in training the neuroradiologists and interventional physicians. The navigability of the tested covered stents becomes decreased with the increasing of its length. (authors)