The objective of this report was to study the performance of different covered stents as bridging stent grafts in a plain fenestrated model. Four different balloon-expandable covered stent grafts (Advanta V12 [Getinge AB, Gothenburg, Sweden], BeGraft [Bentley Innomed GmbH, Hechingen, Germany], BeGraft Plus [Bentley Innomed GmbH], and VBX [Gore Medical, Flagstaff, Ariz], each in 6 mm, 10 of each) were placed in a flat fenestrated model and flared by a 10-mm balloon. After this, the polytetrafluoroethylene (PTFE) fabric was analyzed by a micro camera (Keyence, Milton Keynes, United Kingdom). The stent structure was investigated by radiography. Pullout force was measured by recording force vs displacement to analyze the strength of the connection between the bridging stent graft and the fenestration. Tangential force vs displacement was measured to assess the shear stability of the different stents and to analyze the ability of the stents to resist migration and misalignment of a fenestrated endograft (Fig 1). No damage or rupture of the PTFE fabric was observed in all types of covered stents. Moreover, no stent fractures in any of the covered stents was seen by radiography. Maximal pullout force for 6-mm stents was 16.9 ± 1.9 N for the Advanta V12, 23.0 ± 4.3 N for the VBX, 17.6 ± 1.3 N for the BeGraft, and 28.1 ± 4.2 N for the BeGraft Plus. The slope of the measured pullout force of these stents in the first part was 2.83 N/mm for the Advanta V12, 1.9 N/mm for the VBX, 1.87 N/mm for the BeGraft, and 2.12 N/mm for the BeGraft Plus. Maximal shear strength was 29.6 ± 3.2 N for the Advanta V12, 20.4 ± 3.1 N for the VBX, 18.9 ± 1.9 N for the BeGraft, and 28.8 ± 2.0 N for the BeGraft Plus. Shear force at 6-mm displacement was 7.2 ± 1.4 N for the Advanta V12, 8.7 ± 1.9 N for the VBX, 6.7 ± 0.8 N for the BeGraft, and 9.6 ± 1.5 N for the BeGraft Plus (Fig 2). The material of all tested covered stents has withstood the flaring forces without damage of the PTFE fabric or stent fracture. Pullout force was highest in the BeGraft Plus, followed by VBX, BeGraft, and Advanta V12, but the slope of the pullout force at the first part was highest in the Advanta V12 stent, followed by BeGraft Plus, VBX, and BeGraft. The ability to withstand crushing forces was highest in Advanta and BeGraft Plus, followed by VBX and BeGraft. These findings together with the special features of the tested stents should have an important implication for clinical practice. Fatigue tests for these stents in this special indication are mandatory to ave a dedicated bridging stent graft for fenestrated aortic repair in the future.Fig 2Shear strength 6-mm bridging stent graft.View Large Image Figure ViewerDownload Hi-res image Download (PPT)