Mild Paravalvular Leak May Pose an Increased Thrombogenic Risk in Transcatheter Aortic Valve Replacement (TAVR) Patients-Insights from Patient Specific In Vitro and In Silico Studies

Figures

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  Figure 1. Creation of CFD domain and mesh from µCT scans of in vitro models—Left box—the process of obtaining patient-specific boundary conditions from hydrodynamic studies and segmentation of µCT models (colored to show components). Top right—final sample reconstructed CFD domain. Bottom right box—Polyhedral mesh showing the resolution within the PVL channels and cell volume distinction.

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  Figure 2. Flow pattern and waveform comparison—Volume of fluid (VOF) rendering of the fluid velocity of the CFD solution in systole (left) and diastole (right). Overlays of the flow waveform, comparing the in vitro and in silico solutions, with systole (green) and diastole (gray) timepoints labeled.

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  Figure 3. Evidence of platelet entering and reentering in both flow phases—Left shows platelets entering the PVL channels of Anatomy A in both systolic phase and diastolic phase. Right shows a pathline of platelet from (A) entering the channel in systole, (B) reentering in diastole and recirculation for another cycle, (C) exiting in 3rd systole into the aorta, and finally (D) washing through the PVL channel in the final diastolic phase.

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  Figure 4. Polar projections of pathlines of the top 3000 highest SA platelets—Top—key to visualize the polar projection with red arrow demonstrating projection angle. From top to bottom are each of the patient-specific anatomies A–E. Left-column platelets are colored and sized according to the velocity magnitude, while right-column platelets are colored by stress magnitude.

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  Figure 5. Probability density function (PDF) of the platelets stress accumulation (SA) comparison —Showing the increased stress accumulation of platelets entering the PVL channels (blue peaks shifted right). Inset graph highlights higher stress values (>5 Pa × s). Each PDF represents the patient-specific anatomies (A–E).

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  Figure 6. Contour plots of LVOT velocity and concentration of platelets entering the PVL domain—Top are velocity contour plots in the LVOT perpendicular to the bottom of the TAVR stent. Bottom contours represent the concentration of the starting position of the PVL platelets in the LVOT, showing concentrations towards the lumen surface. Each column represents the patient-specific anatomies (A–E).

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  Figure 7. Emerging linear trends from the 5 cases—Top row—linear correlations showing the tendency of platelets to enter or reenter the PVL channels. Bottom row—linear correlations of the median and mean stress accumulation of the PVL platelets to the diastolic streamline velocity and the average velocity (>0.3 m/s) in a transverse plane of the LVOT.