Abstract
BackgroundMitral annuloplasty rings restore annular dimensions to increase leaflet coaptation, serving a fundamental component in mitral valve repair. However, biomechanical evaluations of annuloplasty rings are lacking. We aim to biomechanically analyze flexible and rigid annuloplasty rings using an ex vivo mitral annular dilation model.MethodsJuvenile porcine mitral valves (n = 4) with intercommissural distance of 28 mm were dilated to intercommissural distances of 40 mm using a 3D-printed dilator and were sewn to an elastic mount. Fiber bragg grating sensors were anchored to native chordae to measure chordal forces. The valves were repaired using size 28 rigid and flexible annuloplasty rings in a random order. Hemodynamic data, echocardiography, and chordal force measurements were collected.ResultsMitral annular dilation resulted in decreased leaflet coaptation height and increased mitral regurgitation fraction. Both the flexible and rigid annuloplasty rings effectively increased leaflet coaptation height compared to that post dilation. Rigid ring annuloplasty repair significantly decreased the mitral regurgitation fraction. Flexible annuloplasty ring repair reduced the chordal rate of change of force (7.1 ± 4.4 N/s versus 8.6 ± 5.9 N/s, p = 0.02) and peak force (0.6 ± 0.5 N versus 0.7 ± 0.6 N, p = 0.01) compared to that from post dilation. Rigid annuloplasty ring repair was associated with higher chordal rate of change of force (9.8 ± 5.8 N/s, p = 0.0001) and peak force (0.7 ± 0.5 N, p = 0.01) compared to that after flexible ring annuloplasty repair.ConclusionsBoth rigid and flexible annuloplasty rings are effective in increasing mitral leaflet coaptation height. Although the rigid annuloplasty ring was associated with slightly higher chordal stress compared to that of the flexible annuloplasty ring, it was more effective in mitral regurgitation reduction. This study may help direct the design of an optimal annuloplasty ring to further improve patient outcomes.
Highlights
Mitral valve regurgitation (MR) is one of the most prevalent causes of global morbidity and mortality [1]
We showed that flexible annuloplasty rings were associated with lower chordal forces compared to that measured in the post dilation state, and it has been theorized that when the optimal coaptation surface is disrupted, as in the case with mitral valves with dilated annulus, the chordae are forced to take on additional forces [30]
In conclusion, our dilation system was successful in generating an isolated mitral annular dilation model with associated MR
Summary
Mitral valve regurgitation (MR) is one of the most prevalent causes of global morbidity and mortality [1]. The primary purpose of annuloplasty ring implantation is to restore healthy mitral annular dimensions in an effort to increase leaflet coaptation and to prevent future annular dilatation [6,7,8,9,10,11,12]. A number of mitral valve annuloplasty rings exist with different rigidities, the biomechanical understanding of annuloplasty rings is lacking. Limited information is available regarding the biomechanical and hemodynamic effects after repair using rigid versus flexible mitral annuloplasty rings [13, 14]. It is prudent to obtain a better understanding of the biomechanical and hemodynamic impact of flexible versus rigid annuloplasty ring on mitral valves. Mitral annuloplasty rings restore annular dimensions to increase leaflet coaptation, serving a funda‐ mental component in mitral valve repair. We aim to biomechanically analyze flexible and rigid annuloplasty rings using an ex vivo mitral annular dilation model
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