Biomechanical engineering analysis of neochordae length's impact on chordal forces in mitral repair.

OBJECTIVES: Artificial neochordae implantation is commonly used for mitral valve (MV) repair. However, neochordae length estimation can be difficult to perform. The objective was to assess the impact of neochordae length changes on MV haemodynamics and neochordal forces.

METHODS: Porcine MVs (n = 6) were implanted in an ex vivo left heart simulator. MV prolapse (MVP) was generated by excising at least 2 native primary chordae supporting the P2 segments from each papillary muscle. Two neochordae anchored on each papillary muscle were placed with one tied to the native chord length (exact length) and the other tied with variable lengths from 2x to 0.5x of the native length (variable length). Haemodynamics, neochordal forces, and echocardiography data were collected.

RESULTS: Neochord implantation repair successfully eliminated mitral regurgitation with repaired regurgitant fractions of approximately 4% regardless of neochord length (p < 0.01). Leaflet coaptation height also significantly improved to a minimum height of 1.3 cm compared with that of MVP (0.9 ± 0.4 cm, p < 0.05). Peak and average forces on exact length neochordae increased as variable length neochordae lengths increased. Peak and average forces on the variable length neochordae increased with shortened lengths. Overall, chordal forces appeared to vary more drastically in variable length neochordae compared with exact length neochordae.

CONCLUSIONS: MV regurgitation was eliminated with neochordal repair, regardless of the neochord length. However, chordal forces varied significantly with different neochord lengths, with a preferentially greater impact on the variable length neochord. Further validation studies may be performed before translating to clinical practices.