A Novel Selectively Flexible Mitral Annuloplasty Ring Designed Based on Human Imaging with Superior Performance in Hemodynamics, Biomechanics, and Annular Dynamics - A Comprehensive Bench to in vivo Large Animal Analysis

Introduction: We designed a novel mitral annuloplasty ring based on healthy human imaging to allow for the mitral valve (MV) annular conformational changes while restricting the anteroposterior (AP) distance. The objectives were to evaluate ex vivo biomechanics of the novel ring and to validate the annular dynamics after ring implantation in vivo. Methods: Cardiac MRI exams were obtained for 3 healthy volunteers. The MV annulus was tracked (Fig. A-C). Based the imaging data, a novel ring was manufactured (Fig. D-F). An ex vivo annular dilation model of mitral regurgitation was used in a left heart simulator (Fig. G, H) to measure hemodynamics and chordal forces at dilated baseline and after repair using the novel, rigid, and flexible rings in 5 porcine MVs. Novel (n = 6) or rigid rings (n = 5) were implanted into male Dorset sheep. Pre- and post-operative cardiac MRI exams were analyzed. Results: Repair using the novel, rigid, and flexible ring reduced regurgitation fraction from 30.0 ± 5.8% at dilated baseline to 4.7 ± 2.7%, 2.4 ± 3.2%, and 17.8 ± 10.0% ( p < .0001, Fig. I-N ). Peak forces on the primary chordae decreased after ring annuloplasty repair ( p < .0001, Fig. O ). The novel ring also showed lower peak forces compared to the rigid ring (p = .03) in secondary chordae ( Fig. P ). MV annular motion was preserved in vivo using the novel ring but restricted to a planar geometry using the rigid ring ( Fig. Q-S ). Annular height to intercommissure ratio at midsystole were similar pre-repair (0.2 ± 0.1) and after novel ring repair (0.2 ± 0.0, p = .89). The variance of AP distance during the cardiac cycle was similar between the novel (0.4 ± 0.3) and rigid ring (0.5 ± 0.1, p = .58). Conclusions: This novel mitral annuloplasty ring demonstrated excellent capability in reducing AP dimension and repairing regurgitation with a superior chordal force profile while facilitating the annular flexible motion. Future studies will focus on evaluating repair durability and effect on left ventricular remodeling.