Background: Valvular heart diseases (VHD) affect about 13% of the elder population (>75), which represents more than 100 million people worldwide. The only available treatment is heart valve replacement, either with mechanical or biological prostheses. Mechanical prostheses provide long-term durability, but inevitably bring along a high risk of thromboembolism. On the other hand, biological prostheses provide better hemo/biocompatibility, but they are prone to degeneration. Alternatively, polymeric (particularly polyurethane(PU)-derived) materials have been suggested and investigated as potential heart valve biomaterials.

Aims: To develop and test innovative non-isocyanate polyhydroxyurethanes (PHUs) for prosthetic heart valves, with improved mechanical and anti-thrombogenic properties, resulting in enhanced hemocompatibility.

Methods: PHUs were obtained by polyaddition between different bis-cyclic-carbonates and amines. The ultimate tensile strength (MPa), strain (%) and elastic modulus (MPa) of synthesized PHUs were measured under dry and wet conditions and compared to native valves. Hemolysis tests were performed in the presence of washed red blood cells from human blood. The activation of the complement and coagulation cascade was evaluated after incubation of the PHU samples with citrate-anticoagulated platelet-poor plasma. Platelet adhesion was quantified upon incubation of the samples with platelet-rich plasma.

Results: A Dacron reinforcement of the selected PHU rendered mechanical properties that were comparable to the ones of a native valve. This PHU did not cause hemolysis or complement activation, it induced less coagulation activation than medical grade PU, and caused extremely low levels of platelet adhesion. A tri-leaflet prosthetic heart valve with a precisely defined design was produced by injection molding.

Conclusion(s): PHU materials displayed overall improved hemocompatibility. A cost effective, environmentally friendly and mechanically competent prosthetic heart valve was developed and could be further explored as an alternative for valve replacement in VHD patients.

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/polymeric-prosthetic-heart-valves-with-low-thrombogenicity/