Understanding the Mechanisms Behind the Annuloplasty Effect in Tricuspid Valve TEER: A Computational Study

BackgroundAn annuloplasty effect has been observed following tricuspid transcatheter edge-to-edge repair (TEER) and has been shown to have a therapeutic benefit. However, the mechanisms underlying the annuloplasty effect remain unknown. ObjectivesWe investigate the impact of TEER-induced annular forces on the annuloplasty effect. Additionally, we explored the impact of clip size, clip orientation, leaflet pair, and leaflet site on TEER-induced annular forces. MethodsWe simulated 36 TEER repairs in finite element models of three human tricuspid valves. We used either a NTW or XTW TriClip. The clip was placed between either the anterior-septal or anterior-posterior leaflet pairs, in either the central or near-annulus site. For each scenario, we quantified the reduction in annular area, septal-lateral (SL) diameter, and anterior-posterior (AP) diameter. We also report the total annular force, orientation of maximum annular force, total papillary muscle force, leaflet stress, and coaptation area ratio following TEER. ResultsTEER induced annular forces, which strongly predicted the annuloplasty effect as measured by reduction in annular area and SL diameter. The maximum annular force aligned with the orientation of the clip. Furthermore, XTW clips induced more annular force and leaflet stress than NTW clips. A central anterior-posterior site induced more force than a near-annulus anterior-posterior site, but showed no difference from an anterior-septal pair. ConclusionsTEER procedural parameters, such as clip size and site, strongly influence the magnitude of induced annular forces, which, in turn, correlate with the degree of annuloplasty effect.