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

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.

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.

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.

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.