Stent segments to improve the compliance of textile vascular grafts: preliminary assessment

Textile vascular grafts can be considered as the gold standard in vascular surgery for aneurysm treatment or vessel bypass and reconstruction. They have been used successfully for decades, especially for the treatment of medium and large vessel diameters. The compliance of these implants, which are made from woven or knitted fabric, is however limited due to the lack of elasticity of the textile they are made of. This limits their use for small caliber vessels. The goal of this work is to present a strategy to improve the elasticity of the textiles used, by combining them with metallic zigzag-shaped stent segments. In a preliminary approach, to validate the concept, diagonally oriented woven monofilament and multifilament medical grade textile strips were assembled with NiTi stent segments. Extension and relaxation tests were performed on stented and nonstented strips to assess the spring back effect provided by the stent segments. Results bring out that the spring back effect can be increased by nearly 300% for a multifilament material and 50% for a monofilament material. Shaping these materials in tubular geometries would provide the tubes with compliance values up to 3.5%.