Patient-specific Optimization of Mitral Valve Annuloplasty Surgery
Amir H. Khalighi1, Bruno V. Rego1, Andrew Drach1, Robert C. Gorman2, Jospeh H. Gorman, III2, Michael S. Sacks1.
1The University of Texas at Austin, Austin, TX, USA, 2University of Pennsylvania, Philadelphia, PA, USA.
Objectives: Mitral regurgitation (MR) is afflicting the western world with an ever-increasing prevalence rate. Over the past two decades, we have seen hallmark advancements in MR therapy, particularly via annuloplasty (AP) repair techniques; however, severe MR ultimately recurs in 30% of patients after surgery. While a lack of consensus remains regarding the optimal approach to mitral valve (MV) repair or AP ring design, biomechanical simulations are beginning to play a vital role in advancing these endeavors. In this work, we have analyzed simulated MV repair surgeries to discern what features of various AP ring designs best restore healthy MV tissue behavior, and thus show greater promise for ensuring long-term repair success.
Methods: We acquired 3D transesophageal echocardiography (TEE) images of 5 ovine mitral valves 8 weeks after they underwent an induced posterobasal infarction. The images were segmented to extract leaflet geometries (Fig. 1a) that were then integrated with mechanically equivalent chords to build complete patient-specific MV models (Fig. 1b). Next, we simulated the closing behavior of each MV and the valvular response to different AP rings through finite element analysis.
Results: The results showed that areal size of AP ring impacts MV repair more significantly than ring's saddle height, although both metrics affected repair performance (Fig. 1c). On average, we found that 10% undersized rings with 7% saddle best restore the normal MV response on a population level. However, even using optimal average features, individual outcomes varied considerably, and AP rings with personally customized areal size and saddle height offered substantial benefits on a patient-specific basis.
Conclusions: There is an ongoing debate on the optimal size, shape, and mechanical characteristics of the AP rings to repair the MV. In this work, we developed complete MV models directly from 3D TEE images, then simulated patient-specific mitral AP surgery on them. We strongly believe that our framework can be extended to guide ring selection in AP surgery and, in turn, improve the MV repair durability and robustness.
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