A Simulation Study of the Effects of Number and Location of MitraClips on Mitral Regurgitation

Abstract

Background: MitraClip (MC) is a device that is implanted on the mitral valve (MV) percutaneously to treat severe mitral regurgitation (MR). It is common practice to place the MCs at the site of the most significant MR jets identified by echocardiography.

Objectives: We used computational modeling to examine changes in MR after MC placement.

Methods: Echocardiographic images from 29 patients with MR were analyzed to reconstruct geometries for finite element simulations and created fluid structure interaction models of the MV with deformable hyperelastic material, the left ventricle as the surrounding geometry, and blood flow. Blood flow was modelled with smoothed particle hydrodynamics. The number of blood particles on the atrial side of MV was used to estimate MR. MC placement was based on the MR jets (jet-based strategy using primary and secondary jets) and simulation models using various MCs locations.

Results: Computational modelling was able to quantitate reductions in MR after MC placement. Reduction in MR was related to the number of MCs used: 42% reduction with 1 MC, 62% with 2 MCs, and 88% with 3 MCs. Using 2 MCs did not always result in an MR reduction greater than with a single MC. In 31% (9 of 29) of patients, the jet-based strategy did not lead to maximum MR reduction. The majority of patients (89%) who did not have maximal MR reduction with the MC placement using the jet-based strategy, had wide jets, and/or had multiple jets.

Conclusions: Subject-specific simulation models may be helpful to identify optimal locations for MC placement in patients with MR.

Keywords: MitraClip; intervention; mitral regurgitation; mitral valve; simulation.

Graphical abstract

Figure 1

The Valve Geometry and the 6 Locations Where an MC Can be Implanted Four landmark points were used to morph the mitral valve geometry based on 3-dimensional echo images. Clip placement location is defined as C1-6. MC = MitraClip.

Figure 2

The Average Percentage MR Reduction for 1-, 2-, and 3-Clip Scenarios The MR reduction is relative to no clip condition (baseline MR). Clip placement location is defined as C 1-6 based on Figure 1. MC = MitraClip; MR = mitral regurgitation.

Figure 3

MR Reduction by 1, 2, and 3 Clips (Patient ID 25) The MR reduction is relative to no clip condition (baseline MR). Abbreviations as in Figure 2.

Figure 4

MR Reduction by 1, 2, and 3 Clips (Patient ID 26) The MR reduction is relative to no clip condition (baseline MR). Abbreviations as in Figure 2.

Figure 5

Implanting the MCs by Following Regurgitation Jets The first MC was placed at the location of the strongest jet. Then, the second MC was placed at the location of the secondary jet. Four sample patients are shown here. Clip placement location is defined as C 1-6 based on Figure 1. MC = MitraClip.

Figure 6

Analysis of MC Procedure Outcomes Based on Regurgitation Jets In 31% of cases in this series, using the location of the MR jets (jet-based strategy) for MC placement did not lead to an optimal MR reduction. In cases without optimal MR reduction, 89% had either a wide jet or multiple jets. “Unknown” refers to simulations that did not converge or baseline MR was negligible. MR = mitral regurgitation.

Central Illustration

The Locations of Mitral Clips According to the Jet-Based Strategy and the Maximal Mitral Regurgitation Reduction Simulation Model for 3 Sample Patients The locations of mitral clips according to the jet-based strategy (orange arrows) and the maximal mitral regurgitation reduction simulation model (blue arrows) for 3 sample patients. The respective baseline mitral regurgitation jets are shown on the right.