The square stent-based large vessel occluder: An experimental pilot study

PURPOSE: The purpose of this study is in vitro and in vivo experimental eva luation of a square stent-based vascular occlusion device for large vessels , MATERIALS AND METHODS: Square stent-based large vessel occluders (LVO) 5 mm -50 mm in size were constructed from stainless-steel square stents covered by porcine small intestine submucosa (SIS), The LVOs with two back-side bar bs were delivered through a guiding catheter, The LVOs with two back-side b arbs and two frontal barbs were front-loaded and delivered coaxially, A pus her with a retention mechanism at its end was used for deployment, In vitro testing for competency was performed with use of a flow model with pressur e increases, In an experimental pilot study in seven pigs and five dogs, 16 LVOs were placed into the aorta (n = 4), common iliac artery (n = 2), pulm onary artery (n = 4), and medial sacral artery (n = 6), Four animals receiv ed two LVOs in different locations, Angiography was performed before and af ter placement of each LVO, Animals were followed for as long as 3 months wi th use of angiography and were then killed for gross and histologic evaluat ion, RESULTS: In vitro LVOs with two and four barbs were easily collapsed and pu shed through or front-loaded into guiding catheters (6-F for a 5-mm occlude r, 10-F for a 50-mm occluder). A 20-mm LVO adapted to tubular structures 10 -15 mm in diameter, forming polygons 17-18.5 mm in length, In the flow mode l, LVOs endured pressure increases to 300 mm Hg, In vivo, the LVOs self-exp anded and adapted to the vessel without migration in all cases, The locking pusher allowed precise LVO placement and engagement of its barbs into the vessel wall before complete deployment, preventing dislodgment by blood flo w, Complete arterial occlusion occurred within 10-20 minutes and arteries r emained occluded until the animal was killed in all cases, After 2 months, histologic evaluation revealed replacement of SIS by host tissue and its re modeling with variable fibrocytes, fibroblasts, and some inflammatory cells , Complete endothelialization was seen on both sides of the LVO, CONCLUSION: The SIS LVO is effective and reliable for acute and chronic occ lusion in a high flow model in an experimental animal.