Flow Mediated Causes of Thrombosis in Transcatheter Heart Valves

Abstract

The recent unexpected discovery of thrombosis in transcatheter heart valves (THVs) has led to increased concerns of long-term valve durability. Based on the clinical evidence combined with Virchow’s triad, the primary hypothesis is that low-velocity blood flow around the valve could be a primary cause for thrombosis. Using a combination of medical image data analysis and novel single-camera volumetric velocimetry technique, the flow mediated causes for thrombosis in THVs was investigated. Patient data analysis revealed that the occurrence of thrombosis was significantly correlated to valve implantation depth. Preliminary in-vitro flow studies showed that a change in valve implantation depth can lead to a 7-fold decrease in flow stagnation zone size. Advanced three-dimensional velocimetry demonstrated that large volumetric regions of flow stagnation were observed in the vicinity of the THV throughout the cardiac cycle. The volumetric scalar viscous shear stress quantified via the three-dimensional shear stress tensor was within the range of low shear-inducing thrombosis observed in the literature. Such high-fidelity volumetric quantitative data and novel imaging techniques used to obtain it will enable fundamental investigation of heart valve thrombosis in addition to providing a reliable and robust database for validation of computational tools.

VRISHANK RAGHAV

Department of Aerospace Engineering, Auburn University