Ex vivo biomechanical analysis of flexible versus rigid annuloplasty rings in mitral valves using a novel annular dilation system

Yuanjia Zhu; Annabel M Imbrie-Moore; Robert J Wilkerson; Michael J Paulsen; Matthew H Park; Y Joseph Woo

doi:10.1186/s12872-022-02515-x

Ex vivo biomechanical analysis of flexible versus rigid annuloplasty rings in mitral valves using a novel annular dilation system

BMC Cardiovasc Disord. 2022 Feb 26;22(1):73. doi: 10.1186/s12872-022-02515-x.

Authors

Yuanjia Zhu^{1

2}, Annabel M Imbrie-Moore^{1

3}, Robert J Wilkerson¹, Michael J Paulsen¹, Matthew H Park^{1

3}, Y Joseph Woo^{4

5}

Affiliations

¹ Department of Cardiothoracic Surgery. Falk Cardiovascular Research Center, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA, 94305, USA.
² Department of Bioengineering, Stanford University, Stanford, CA, USA.
³ Department of Mechanical Engineering, Stanford University, Stanford, CA, USA.
⁴ Department of Cardiothoracic Surgery. Falk Cardiovascular Research Center, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA, 94305, USA. joswoo@stanford.edu.
⁵ Department of Bioengineering, Stanford University, Stanford, CA, USA. joswoo@stanford.edu.

Abstract

Background: Mitral 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.

Methods: Juvenile 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.

Results: Mitral 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.

Conclusions: Both 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.

Keywords: Biomechanics; Mitral annular dilation; Mitral annuloplasty ring; Mitral regurgitation.

Publication types

Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Animals
Dilatation
Heart Valve Prosthesis*
Humans
Mitral Valve / diagnostic imaging
Mitral Valve / surgery
Mitral Valve Annuloplasty* / adverse effects
Mitral Valve Insufficiency* / diagnostic imaging
Mitral Valve Insufficiency* / surgery
Prosthesis Design
Swine

Grants and funding

R01 HL152155/NH/NIH HHS/United States