Analysis of thrombosis risk of commissural misaligned transcatheter aortic valve prostheses using particle image velocimetry

Due to excellent clinical results, transcatheter aortic valve replacement (TAVR) has evolved to a treatment option for patients with low surgical risk, resulting in an increasing demand for durable heart valve prostheses. Durability of TAVR could be limited by leaflet thrombosis. Thrombus formation in the aortic root is mainly affected by the hemodynamic situation, which is dependent on the positioning of the implant. We investigated the flow field in the aortic root after TAVR implantation by means of particle image velocimetry. To quantify the influence of the implant-position with respect to an alignment or misalignment of the leaflet commissures on the thrombogenic potential, we used a transport equation for residence time (RT) to consider washout behavior. Furthermore, we introduced a shear effect criterion (SIE) to address platelet activation as a measure for a potential thrombus formation. Misaligned implantation of a TAVR resulted in a reversed direction of rotation of the occurring recirculation area. This led to fluid flow with comparable areas of increased relative blood RT (RTaligned: 97.6%, RTmisaligned: 88.0%) and a smaller area of low shear load for the misaligned TAVR (SIEaligned: 57.7%, SIEmisaligned: 3.70%) into the sinus region, indicating a higher potential for thrombus formation.

Automated summary

Due to its clinical success, transcatheter aortic valve replacement (TAVR) has become a viable treatment option for low surgical risk patients, leading to an increased demand for durable heart valve prostheses. However, the durability of TAVR may be limited by leaflet thrombosis which is influenced by the positioning of the implant. This study investigated the flow dynamics in the aortic root after TAVR using particle image velocimetry and found that misalignment of the implant resulted in changes in flow direction, increased blood residence time, and lower shear load, indicating a higher potential for thrombus formation.