Abstract 12588: Biomechanical Analysis of Neochordal Mitral Valve Repair Geometry to Quantitate the Impact of Diastolic Phase Inversion During Static Left Ventricular Pressurization

Abstract

Introduction: Artificial neochord implantation is a common form of surgical mitral valve (MV) repair, and neochord length is commonly determined by static left ventricular (LV) pressurization in diastole. However, this causes a geometric phase inversion as the subvalvular apparatus will dilate when the LV would be contracting during systole in a beating heart. We hypothesize that static LV pressurization and the subsequent papillary muscle (PM) geometric shift affects the implanted neochord length, which may alter hemodynamic performance and chordal stresses. Methods: Porcine MV (n=6) were explanted and mounted in an ex vivo heart simulator and PM were affixed to image-guided robots that accurately simulate PM motion (Fig A, B). Baseline valve hemodynamic and chordal strain data were collected, after which P2 chordae were severed to simulate posterior leaflet prolapse from chordal rupture and subsequent mitral regurgitation (MR) (Fig C). Neochord implantation was performed in both systolic and diastolic stationary PM configurations. Data is presented as mean ± standard error, and statistics were performed using two-tailed Student’s T-Tests. Results: While both repairs adequately reduced MR, we found that the systolic vs diastolic configuration repair resulted in marginally reduced MR and neochord lengths, 2.25±1.384% and 2.19±0.4 mm or 16.0±3.2%, respectively ( p=0.011 , p=0.004 ). Moreover, peak primary and secondary chordal forces were reduced by 14.4±7.0% ( p=0.07 ) and 18.8±6.4% ( p=0.03 ), respectively. Conclusions: By leveraging advanced ex vivo technologies and biomechanics analyses, we were able to quantify the impact of diastolic phase inversion on neochordal MV repair geometry. Our findings suggest that this technique may slightly overestimate the neochordal length and that marginal additional shortening of neochordae may positively affect MV repair performance and durability by reducing load on surrounding native chordae.