Abstract
Only mechanical and biological heart valve prostheses are currently commercially available. The former show longer durability but require anticoagulant therapy; the latter display better fluid dynamic behavior but do not have adequate durability. New Polymeric Heart Valves (PHVs) could potentially combine the hemodynamic properties of biological valves with the durability of mechanical valves. This work presents a hydrodynamic evaluation of 2 groups of newly developed supra-annular, trileaflet prosthetic heart valves made from styrenic block copolymers (SBC): Poli-Valves. 2 types of Poli-Valves made of SBC and differing in polystyrene fraction content were tested under continuous and pulsatile flow conditions as prescribed by ISO 5840 Standard. A pulse duplicator designed ad hoc allowed the valve prototypes to be tested at different flow rates and frequencies. Pressure and flow were recorded; pressure drops, effective orifice area (EOA), and regurgitant volume were computed to assess the behavior of the valve. Both types of Poli-Valves met the minimum requirements in terms of regurgitation and EOA as specified by the ISO 5840 Standard. Results were compared with 5 mechanical heart valves (MHVs) and 5 tissue heart valves (THVs), currently available on the market. Based on these results, PHVs based on styrenic block copolymers, as are Poli-Valves, can be considered a promising alternative for heart valve replacement in the near future.
Highlights
Nowadays, 2 major types of implantable artificial heart valves are available: mechanical and bioprosthetic heart valves
All the tested Poli-Valves exceeded the minimum performance requirements set by the ISO 5840 Standard (Fig. 5): all the 16 Polymeric heart valves (PHVs) showed effective orifice area (EOA)>1 cm2 and a regurgitant volume
The results from continuous and pulsatile flow tests demonstrated that the transvalvular pressure drop is related to the stiffness of the polymer, which increases with polystyrene mass percentage in the material (Figs. 4A and 5A)
Summary
2 major types of implantable artificial heart valves are available: mechanical and bioprosthetic heart valves. Despite the widespread use of artificial heart valves, neither MHVs nor THVs are free from complications. The former show high turbulent stresses, platelet activation, endocarditis, thromboembolic events arising from clot formation and their subsequent detachment. Polymeric heart valves (PHVs) were developed in order to combine the durability of the MHVs with the hemocompatibility of the THVs. The first flexible-leaflet prosthetic heart valves were implanted in the 1960s but, synthetic heart valves exhibit acceptable short-term mechanical properties, their susceptibility to hydrolytic and oxidative biodegradation and subsequent mechanical failure have limited their successful use [4, 5]
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