A novel polymer for potential use in a trileaflet heart valve

Abstract

A novel polyolefin, poly(styrene-b-isobutylene-b-styrene) (Quatromer), is being proposed as a viable polymer for use in trileaflet heart valves because of its oxidative stability. The current study was designed to assess the polymer's hemocompatibility and mechanical durability. Mechanical characterization included static tensile tests and dynamic tension-tension and bending fatigue tests, where the properties of isotropic and composite (polypropylene (PP) embedded) Quatromer specimens were compared with those of a polyurethane (PUR) approved for cardiovascular applications. It was found that by embedding PP fibers into the Quatromer matrix, the tensile and fatigue properties of the polymer could be improved, making them comparable, if not better than the PUR. The thrombotic potential of Quatromer was compared with the PUR, glutaraldehyde-fixed porcine valve material, and a positive and negative control by measuring platelet deposition with radiolabeled platelets in a parallel plate flow configuration. The porcine valve material was found to have significantly higher platelet deposition under all flow regimes, while no significant difference existed between Quatromer and PUR. In conclusion, Quatromer is shown to have suitable hemocompatibility and mechanical durability for use in polymer trileaflet heart valves, and fiber reinforcement can effectively be used to tailor the mechanical properties.

The effect of water absorption on the viscoelastic properties of poly(styrene-block-isobutylene-block-styrene) for use in biomedical applications

“…Multiple studies have addressed the biocompatibility of SIBS, and have focused on hemocompatiblity, platelet activation and long-term stability in contact with metals [3,[7][8][9][10]. Biocompatibility is not affected by changing the block composition of SIBS [1], which allows tailoring of the mechanical properties according to the specific needs of different implants.…”

Durability Assessment of Polymer Trileaflet Heart Valves

“…SIBS has been proven to be stable in oxidative and acidic environments through a combination of degradation resistance and in vivo transplantation [8]; it has been proven to be equally as thromboresistant as polyurethane by measuring platelet deposition with radiolabelled platelets in a parallel plate flow configuration [7]; and the fatigue resistance of fiberreinforced SIBS has been proven through a combination of cyclic tensile and bending fatigue tests [7]. The numerous different iterations of valve designs that have been evaluated include: different reinforcement techniques, variable valve geometries, varying stent flexibilities, and variable SIBS formulations [9][10][11][12][13][14].…”

“…With this in mind, a polyolefin, poly(styrene-b-isobutylene-b-styrene) (also known as polystyrenepolyisobutylene-polystyrene, or "SIBS), was chosen for the development of the novel trileaflet heart valve. The polymer's physical properties place it between polyurethane and silicone, and its inertness to oxidative and acidic environments, such as the body, has been proven through a combination of degradation resistance and in vivo transplantation [7,8]. Preliminary studies of both the completed SIBS valve and material samples have revealed:…”

“…The adoption of SIBS for the polymer valve is proposed to overcome the problem of biostability, where preliminary testing has proven it to be stable in both in vitro [8] and in vivo [11,14] oxidative environments.…”

Development and evaluation of a catheter deliverable artificial aortic heart valve prosthesis and delivery system

“…the mixture was 15% SIBS and 85% toluene. [58] Commercially available aluminum foil was used as a gasket between the fabric and the drying plate in order to provide a space for SIBS to coat the surface of the polyester fabric in contact with the mirror finish base of the drying fixture. mm diameter was chosen for the PHV prototype.…”