Role of Neo-Sinus on Thrombogenicity of Aortic Valve Prostheses: Experimental Proof-of-Concept Study.

Abstract

Purpose: Transcatheter aortic valve replacement (TAVR) is the standard treatment for patients with aortic diseases at high surgical risk. Transcatheter heart valve prostheses (THV) are inserted into the aortic valve, creating a new area between the native and artificial leaflets. This area, known as neo-sinus, increases the thrombogenicity of THVs. But there is a lack of testing methods that evaluate thrombogenicity in vitro.

Methods: To analyze the flow field within the native sinus and the neo-sinus, Particle Image Velocimetry (PIV) was performed with a thrombosis tester. Additionally, a comparative study was conducted with porcine blood on two polycarbonate urethane valves, with and without neo-sinus, respectively. Blood samples collected every hour were analyzed for platelet count, coagulation via ROTEM parameters, and plasma-free hemoglobin. Thrombus formation was detected optically.

Results: The PIV measurements yield a physiological flow field in the aortic root that were consistent with those reported in literature. The analyzed blood parameters reveal no obvious difference between the valve with neo-sinus and the valve without. A higher amount of thrombus material for the valve with neo-sinus was found.

Conclusion: The visualized flow field shows low velocities and stagnation zones due to the presence of native leaflets. Clot formation at the heart valve prostheses are in accordance with in-vivo findings. The benchmark of the two valves indicates an increased thrombogenic potential due to the neo-sinus. The thrombosis tester simulates the natural environment after TAVR. Thereby, newly developed THVs can be evaluated in vitro and consequently optimized regarding their thrombogenicity.