Thrombogenic Potential of Innovia Polymer Valves versus Carpentier-Edwards Perimount Magna Aortic Bioprosthetic Valves

Abstract

Trileaflet polymeric prosthetic aortic valves (AVs) produce hemodynamic characteristics akin to the natural AV and may be most suitable for applications such as transcatheter implantation and mechanical circulatory support (MCS) devices. Their success has not yet been realized due to problems of calcification, durability, and thrombosis. We address the latter by comparing the platelet activation rates (PARs) of an improved polymer valve design (Innovia LLC) made from poly(styrene-block-isobutylene-block-styrene) (SIBS) with the commercially available Carpentier-Edwards Perimount Magna Aortic Bioprosthetic Valve. We used our modified prothrombinase platelet activity state (PAS) assay and flow cytometry methods to measure platelet activation of a pair of 19 mm valves mounted inside a pulsatile Berlin left ventricular assist device (LVAD). The PAR of the polymer valve measured with the PAS assay was fivefold lower than that of the tissue valve (p = 0.005) and fourfold lower with flow cytometry measurements (p = 0.007). In vitro hydrodynamic tests showed clinically similar performance of the Innovia and Magna valves. These results demonstrate a significant improvement in thrombogenic performance of the polymer valve compared with our previous study of the former valve design and encourage further development of SIBS for use in heart valve prostheses.

A Computational Tool for the Microstructure Optimization of a Polymeric Heart Valve Prosthesis

“…for application in heart valve prostheses have been demonstrated [3,9,[27][28][29][30]. Further, our group has recently shown the possibility of tuning the microstructure and, consequently, the mechanical properties of this type of polymer by compression and slow injection molding: the investigation of thin molded films of poly(styrene-block-isoprene-block-styrene), a block copolymer characterized by a cylindrical morphology, revealed a layered orientation of the cylinders which depends on the conditions during the manufacturing process (i.e., flow rate and temperature) [31,32]; this layered structure leads to a strong anisotropy of the material, as demonstrated by mechanical tests of material samples.…”

In Vitro Evaluation of a Novel Hemodynamically Optimized Trileaflet Polymeric Prosthetic Heart Valve

“…The results were compared to previous measurements (n ¼ 6) conducted with 21 mm Carpentier-Edwards Fig. 4 (a) The optimized valve compression mold, and (b) the molded xSIBS valve prototype Perimount Magna tissue valves mounted in the same LVAD and to a negative control, in which the LVAD was run without valves [22]. One-way ANOVA statistics were performed on the platelet activation rates (PAR) -the slope of the PAS measured over the 30 min.…”

“…Freshly isolated human platelet activation measurements were taken in the small volume pulsatile LVAD. The xSIBS valve results (n ¼ 6) were compared to prior benchmark tissue valve experiments (n ¼ 6) and to control studies in which the pump was run without valves [22], via a one-way ANOVA. There was no significant statistical difference between the platelet activation rates (PAR) of the tissue valve (PAR ¼ 0.0005 min À1 ) and the xSIBS valve (PAR ¼ 0.0008 min À1 ) (see Fig.…”

“…The bulk flow platelet activation of the valves was measured as previously described [22]. Briefly, 120 ml of blood was obtained from healthy volunteers of both sexes screened for antiplatelet medication and a history of smoking according to institutional IRB protocols.…”

“…We and others have previously utilized such a polymer, the thermoplastic polyolefin poly(styrene-b-isobutylene-b-styrene) or SIBS (Innovia LLC, Miami, FL) [18], to design and test a polymer PHV fabricated from SIBS with embedded Dacron reinforcement mesh, with mixed outcomes [12,14,[22][23][24][25][26]. We continue to collaborate with Innovia, who have since developed an improved version of this polymer, xSIBS [19], which is designed to eliminate the significant dynamic creep of thermoplastic SIBS that has limited its utility in PHVs [27].…”