In Vitro Evaluation of the Gore Viabahn Balloon-Expandable Stent-Graft for Fenestrated Endovascular Aortic Repair

Abstract

Purpose: To evaluate the safety and integrity of a new stent-graft as a potential bridging device in fenestrated stent-grafts using an in vitro fenestrated model. Materials and Methods: Polyester test sheets with ten 6-mm- or 8-mm-diameter fenestrations were used to simulate a fenestrated main body endoprosthesis. In total, 50 Viabahn balloon-expandable (VBX) stent-grafts of varying lengths (29 and 39 mm) and diameters (6, 7, and 8 mm) were implanted in the fitting fenestrations. After release, the 6- and 7-mm-diameter stent-grafts were flared with a 10×20-mm angioplasty balloon; a 12×20-mm balloon was used in the 8-mm-diameter devices. Safety of the devices was defined as absence of fractures detected on radiography or computed tomography (CT), as well as material failure detected by microscopy and water permeability testing. The forces (in Newtons, N) needed for perpendicular dislocation (pullout force) and axial dislocation (shear stress force) were also evaluated. Results: Forty VBX stent-grafts were subjected to digital radiographic imaging and multiplanar CT. None showed any stent fracture. Subsequent microscopy indicated no damage to the fabric or separation of the graft after flaring. Ten VBX stent-grafts underwent water permeability testing after flaring; no water passed through the graft wall during a 10-minute period under an intraluminal pressure at 120 mm Hg. Testing of 25 VBX stent-grafts revealed initial pullout forces between 11.3 and 31 N. Shear stress tests showed that the average force needed to dislocate the stent-grafts by 50% of their diameter ranged between 5.75 and 6.91 N (mean 6.1±0.5 N) for the 6-mm stents and between 3.31 and 5.4 N (mean 4.4±0.8) for the 8-mm stents. Conclusion: This preliminary study demonstrated the applicability of the VBX as a bridging stent-graft in a simulated fenestration model. A comparison with other stent-grafts and clinical assessment are required.

Performance of BeGraft and BeGraft+ Stent-Grafts as Bridging Devices for Fenestrated Endovascular Aneurysm Repair: An In Vitro Study

“…The BeGraft+ devices failed exclusively by deforming and consequently slipping, a failure mode we had observed in earlier experiments with another device. 3 Furthermore, both the pullout and shear forces needed to dislocate the stent-grafts from the fenestrations were significantly higher among BeGraft+ devices and throughout subgroup analysis, which suggests that the material and engineering alterations made for the newer device design did increase material stability. Nevertheless, when compared with pullout testing in branched grafts, 10 both devices show superior results to other bridging stent-grafts.…”

“…In this experiment, pullout forces were tested in 0° direction, mirroring the setup of previous experiments. 3 All prepared stent-grafts mounted in the sheets were tested using a Z005 axial material testing machine (Zwick-Roell, Ulm, Germany; Figure 1A and B).…”

“…Using a standard protocol from prior studies, 3 20 BeGraft stent-grafts (10 each of sizes 6×38 mm and 8×37 mm) and 20 BeGraft+ stent-grafts (10 each of the same sizes) were implanted into the fenestration sheets immersed in a 37°C water bath. The insertion depth mirrored clinical practice with one-third of the stent-graft length on the aortic side and two-thirds on the renal side.…”

Comparison of the Biomechanical Properties of the Advanta V12/iCast and Viabahn Stent-Grafts as Bridging Devices in Fenestrated Endografts: An In Vitro Study

“…The protocol mirrored earlier experiments. 6,7 In total, 40 stent-grafts measuring 6×39 mm and 8×39 mm (10 of each size for each stent-graft) were implanted in the fenestration sheets while they were immersed in a water bath with a temperature of 37°C. The insertion depth of each stent-graft emulated our clinical practice, with approximately one-third of the stent-graft length on the aortic side and two-thirds on the renal side.…”

“…The pullout forces necessary to axially dislocate bridging devices from the fenestrations were tested using a Zwick-Roell Z005 axial material testing machine (Figure 1), as detailed in prior studies. 6,7 Tests started by preconditioning with a low and constant load (2 N). In a next step, the load to complete pullout (displacement ramp) was incrementally applied, starting with settling cycles of 2 N ramped to 3 N and back to 2 N at 20 mm/min.…”