In vivo evaluation of an elastomeric small‐diameter vascular graft reinforced with a highly flexible Nitinol mesh

Abstract

Highly porous small-diameter vascular grafts (SDVGs) prepared with elastomeric materials such as poly(ether urethane) (PEtU)-polydimethylsiloxane (PEtU-PDMS) are capable to biodegrade but may develop aneurismal dilatation. Through a compliance/patency assessment with ultrasound techniques, the current study investigated the functionality, in terms of patency and endothelialization, of a highly flexible and porous Nitinol mesh incorporated into PEtU-PDMS SDVGs in a sheep carotid model. Nitinol-PEtU-PDMS grafts with an internal diameter (ID) of 4 mm were manufactured by spray, phase-inversion technique. Compliance tests were performed by ultrasound (US) imaging using a high-resolution ultrasound diagnostic system. Ten adult sheep were implanted with 7 cm long grafts. The results of this study demonstrated an almost complete neointima luminal coverage in transmurally porous grafts reinforced with the Nitinol meshes after 6 months of implantation. Additionally, ultrasound has been used to quantitatively assess and monitor hemodynamic variables in an experimental model of synthetic vascular graft replacement. The use of reinforced PEtU-PDMS grafts may accelerate the endothelialization process of relatively long grafts, such as those needed for aortocoronary bypass. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2018.

Effect of corrugated structure on the collapsing of the small-diameter vascular scaffolds

“…17 Unfortunately, the grafts made of PU materials can become mechanically weak over time. 34 On the other hand, the synthetic prosthesis may undergo aneurysmal dilatations as a consequence of radial internal pressure. While biomaterial selection is of greatest importance in the long-term success of vascular grafts, so is structural design.…”

Mimicking “J-Shaped” and Anisotropic Stress–Strain Behavior of Human and Porcine Aorta by Fabric-Reinforced Elastomer Composites

“…The problem is aggravated with the lack of Windkessel effect when the heart is ejecting in working mode, where the human aorta acts as a shock-absorbing reservoir to prevent injury from the pulsed supply of blood from the beating heart and to produce “nearly continuous peripheral blood flow” . Conversely, soft tubing materials, such as room-temperature vulcanizing (RTV) silicones, do not allow blood to circulate because of overexpansion at minimal pressure changes …”

“…6 Conversely, soft tubing materials, such as roomtemperature vulcanizing (RTV) silicones, do not allow blood to circulate because of overexpansion at minimal pressure changes. 7 The rapid strain-stiffening of the human aorta, termed the Jshaped stress−strain behavior, 8 allows continuous blood flow by the generation of the Windkessel effect. The Windkessel effect of the aorta constitutes of the following processes.…”