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. 2019 Oct 10;14(10):e0223472.
doi: 10.1371/journal.pone.0223472. eCollection 2019.

Mechanical effects of MitraClip on leaflet stress and myocardial strain in functional mitral regurgitation - A finite element modeling study

Yue Zhang  1   2 , Vicky Y Wang  1   2 , Ashley E Morgan  2 , Jiwon Kim  3 , Mark D Handschumacher  4 , Chaya S Moskowitz  5 , Robert A Levine  4 , Liang Ge  1   2 , Julius M Guccione  1   2 , Jonathan W Weinsaft  3 , Mark B Ratcliffe  1   2
Affiliations

Mechanical effects of MitraClip on leaflet stress and myocardial strain in functional mitral regurgitation - A finite element modeling study

Yue Zhang et al. PLoS One. .

Abstract

Purpose: MitraClip is the sole percutaneous device approved for functional mitral regurgitation (MR; FMR) but MR recurs in over one third of patients. As device-induced mechanical effects are a potential cause for MR recurrence, we tested the hypothesis that MitraClip increases leaflet stress and procedure-related strain in sub-valvular left ventricular (LV) myocardium in FMR associated with coronary disease (FMR-CAD).

Methods: Simulations were performed using finite element models of the LV + mitral valve based on MRI of 5 sheep with FMR-CAD. Models were modified to have a 20% increase in LV volume (↑LV_VOLUME) and MitraClip was simulated with contracting beam elements (virtual sutures) placed between nodes in the center edge of the anterior (AL) and posterior (PL) mitral leaflets. Effects of MitraClip on leaflet stress in the peri-MitraClip region of AL and PL, septo-lateral annular diameter (SLAD), and procedure-related radial strain (Err) in the sub-valvular myocardium were calculated.

Results: MitraClip increased peri-MitraClip leaflet stress at end-diastole (ED) by 22.3±7.1 kPa (p<0.0001) in AL and 14.8±1.2 kPa (p<0.0001) in PL. MitraClip decreased SLAD by 6.1±2.2 mm (p<0.0001) and increased Err in the sub-valvular lateral LV myocardium at ED by 0.09±0.04 (p<0.0001)). Furthermore, MitraClip in ↑LV_VOLUME was associated with persistent effects at ED but also at end-systole where peri-MitraClip leaflet stress was increased in AL by 31.9±14.4 kPa (p = 0.0268) and in PL by 22.5±23.7 kPa (p = 0.0101).

Conclusions: MitraClip for FMR-CAD increases mitral leaflet stress and radial strain in LV sub-valvular myocardium. Mechanical effects of MitraClip are augmented by LV enlargement.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Representative FE mesh of the LV with Mitral Valve and MitraClip modeled as virtual sutures.
Views include (A) LV showing postero-lateral MI, (B) en face view of the mitral valve with MitraClip and (C) close up of MitraClip as virtual sutures. The leaflet elements used for stress calculation are marked in orange. BZ–infarct borderzone; RZ–remote myocardium; AL–anterior leaflet; P1,2,3 –posterior leaflet sections; Ao–capped region of aortic outflow and MClp–MitraClip.
Fig 2
Fig 2. The simulation timelines.
Fig 3
Fig 3
Representative Von Mises stress color maps of the mitral valve before (A and D) and after (B and E) virtual MitraClip and after MitraClip in an enlarged LV (C and F). Effects are seen at end- diastole (A—C) and end systole (D—F). Note that these color maps are not dimensionally exact. AL–anterior leaflet; P1,2,3 –posterior leaflet sections; MClip–MitraClip.
Fig 4
Fig 4
Stress in the peri-MitraClip region in the anterior and posterior leaflets at end-diastole (A and B) and end-systole (C and D).
Fig 5
Fig 5
Septo-lateral annular dimension at end-diastole (A) and end-systole (B) at baseline and after simulated partial and complete grasp MitraClip.
Fig 6
Fig 6
Color map of Δ in myocardial radial strain, Err, at end-diastole after simulated complete grasp MitraClip in the baseline LV (A) and in a dilated LV (B). Ao–left ventricular outflow/ aorta region. PA–posterior mitral annulus. MI–myocardial infarction.
Fig 7
Fig 7
Radial strain, 𝐸_𝑟𝑟, after simulated partial and complete grasp MitraClip in the P2 sub-valvular myocardium at end-diastole (A), P2 sub-valvular endocardium at end-diastole (B) and P2 sub-valvular myocardium at end-systole (C) respectively. Err before and after MitraClip is relative to the pre-procedure unloaded state.
Fig 8
Fig 8. Diagram of the proposed mechanical effects of MitraClip application.
The black arrows represent displacement of the posterior leaflet, lateral annulus and lateral sub-valvular LV wall caused by MitraClip application. The effects are to increase leaflet stress, decrease the septo-lateral annular dimension and stretch the sub-valvular myocardium. LV–left ventricle, LA–left atrium, MC–MitraClip.
See this image and copyright information in PMC

References

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