Can a Self-Expanding Aneurysm Stent Be Clipped? Emergency Proximal Control Options for the Vascular Neurosurgeon

Abstract BACKGROUND: If a self-expanding stent has been placed during endovascular treatment of an aneurysm and subsequently an open aneurysm surgery becomes necessary in the same or an adjacent area, is it possible and safe to obtain proximal control by placing a temporary clip on the artery at a point where it contains the stent? OBJECTIVE: To evaluate the effect of temporary clip application to 3 separate stent systems in an in vitro flow model with the stated hypothesis that clip application to these stents will result in permanent stent deformation. METHODS: This is an in vitro flow model study using an accepted synthetic blood vessel substitute. The Neuroform3 (Boston Scientific), Enterprise (Cordis/Codman), and Pipeline (ev3) stents were deployed within the flow model; temporary clips were applied; and angiographic measurements subsequently made. RESULTS: Two 4 × 30-mm Neuroform3 stents, two 4.5 × 28-mm Enterprise stents, and two 3.75 × 20-mm Pipeline stents were successfully deployed and clipped repeatedly (4 iterations). Two- and 3-dimensional angiograms were obtained. After repeated clip occlusion, the Neuroform3 and Enterprise stents returned to their original configuration and diameter. Clip application to both also resulted in immediate flow arrest. In contrast, initial clip application to the Pipeline stents did not result in flow arrest, but the second single clip application did. The Pipeline stents were also irreversibly deformed after the experimental protocol, with an average luminal diameter reduction of 26.85% (P < .05). CONCLUSION: The Neuroform3 and Enterprise stents responded favorably to temporary clip application, returning to their original diameter after clip removal and showing no sign of permanent structural modification. The Pipeline flow-diverting stent, however, was irreversibly deformed by clip application. These data indicate that temporary clip application to certain stents is possible. Further in vivo study is required.