CoreValve vs. Sapien 3 Transcatheter Aortic Valve Replacement: A Finite Element Analysis Study

Figure 1. The integration of preoperative medical images with FEA simulation can describe the impact of uncrushed calcifications on TAVR complications. These studies could be useful in predicting potential risk factors.

Figure 2. Patient’s preoperative CT scans of severe bulky calcifications attached to aortic valve leaflets and root (a,c), compared to the model reconstruction (b,d).

Figure 3. FEA simulations of TAVR in two investigated patients who showed postoperative thrombosis. The positioning (a,a′) and reopening (c,c′) of CoreValve and Sapien devices (left and right sides, respectively), compared to the corresponding intraoperative angiographic images (b,b′).

Figure 4. Postoperative medical images (a,c,a′,c′) compared to the FEA results of the TAVR simulations (b,d,b′,d′, front and top view, respectively) of the CoreValve and Sapien devices. The red areas show paravalvular orifices due to the presence of residual calcifications, and the blue arrows indicate the major distortion of the frames and their incomplete and/or asymmetric expansion.

Figure 5. In the re-hospitalized patient: CoreValve deformation measured through its postimplant eccentricity, computed as a/b, i.e., (minimum radius)/(maximum radius) of 22 equally spaced cross-sections of the frame. In the first chart from above, the blue line describes the real prosthesis deformation, plotted against its longitudinal height (h, growing towards the inferior base of the device), compared to the red one, which represents the perfect circularity (ideal eccentricity ecc: a/b = 1). Three cross-sections (A–C) are highlighted. As expected, the most elliptically deformed device portion is the distal one (C), at the level of the greatest uncrushed calcifications, (mm: millimeter values).

Figure 6. The ideal shape of a Sapien 3 stent frame (upper panels) compared to the real ones after implantation in patients under study. (a) Open device configuration before crimping; (b) perfect frame circularity, when the two principal axes d have the same length, such as the triangle edges a (top view); (c,e) balloon-driven device re-expansion within the investigated patients (thrombotic and control case, respectively); (d,f) evaluation of the implanted stent deformation, proposed as the measure of the three distances between the points at the commissure windows (red dots). [a′ ≠ b′ ≠ c′ ≠ a; a″ ≠ b″ ≠ c″ ≠ a; d1′ and d2′, d1″ and d2″: minor and major axes of the originated ellipses; d1′ ≠ d2′ ≠ d; d1″ ≠ d2″ ≠ d].

Figure 7. From top to bottom, as follows: CoreValve TAVR with postoperative complications (a,b), CoreValve implant as a case control (c,d), Sapien TAVR with consequent thrombosis (e,f), and Sapien implant without any complications (g,h). Contact pressure (CPRESS): measurement of the interaction between the expanded device and the inner aortic surface elements (left panels); von Mises average stress distribution (S, MISES): measure of stress induced by the device expansion onto the aortic wall (to the right).