Biomechanical modeling of surgical techniques to repair isolated segmental P2 prolapse of the mitral valve.

Objective: Prolapse of the P2 cusp of the mitral valve is a common valvular lesion that is amenable to surgical repair. Both resective and nonresective leaflet repair procedures are used, yielding good acute correction of the valve lesion, but with variable resulting valve kinematics and mechanics. In this study, we used a patient-specific computational model of isolated P2 prolapse without excess tissue to assess the mechanical and anatomical benefits of different surgical techniques. Methods: Three-dimensional transesophageal echocardiogram of the mitral valve from a patient with segmental P2 prolapse was segmented and computationally modeled to serve as the disease model. Virtual repair was performed using neochordoplasty, triangular resection, and quadrangular resection. All techniques were accompanied by the addition of true-sized and downsized complete annuloplasty rings. Mitral valve closure was simulated for each repair, and the resulting systolic leaflet geometry, leaflet mobility, leaflet stresses, and chordal forces were computed. Results: From complete loss of coaptation pre-repair, Coaptation length was restored to 5.8 mm with 2 neochordae, 5.9 mm with 4 neochordae, 2.8 mm with triangular resection, and 1.7 mm with quadrangular resection and a true-sized annuloplasty. Peak stress in the repaired P2 segment was initially 0.75 MPa, reduced to 0.47 MPa with 2 neochordae and 0.39 MPa with 4 neochordae, but increased to 0.79 MPa with triangular resection and 2.04 MPa with quadrangular resection. Smaller rings reduced these stresses and further increased coaptation length in all investigated repair scenarios, but with a positive effect of such downsizing being larger with neochordoplasty than resective techniques. Conclusions: In the setting of isolated segmental P2 prolapse, preserving leaflet tissue with neochordae achieved largest leaflet coaptation with lowest leaflet stresses, whereas resective techniques restored smaller coaptation with less stress reduction.