Numerical modeling of diseased mitral valves
Doctoral thesis
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https://hdl.handle.net/11250/3100294Utgivelsesdato
2023Metadata
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Sammendrag
In this thesis, we have developed methods to create digital replicas of patients’ mitral valves from echocardiographic images and perform structural simulations in a finite element framework. The methods allow us to study the mechanics of mitral valve regurgitation and perform in silico surgery to optimize procedures such as annuloplasty repair. We have implemented realistic boundary conditions to all our models, following the true motion of the annulus and papillary muscle to simulate a close-to-reality closure/lack of closure in the simulations. Moreover, we have implemented disease-specific material properties which have shown to be important for the correct global response of the mitral valve. The use of structural simulations to study mitral valve regurgitation and mitral valve repair may provide valuable insights into the function of the mitral valve and help develop optimized treatment options for each individual patient.
With our developed pipeline to study mitral valves with Barlow’s disease, we discovered that for a subset of patients with bileaflet prolapse, late systolic mitral regurgitation, and no chordal ruptures, the annular dilation in late systole is inversely proportional to leaflet separation. We further discovered that this patient group undergoes substantial annular reductions during repair followed by procedures such as leaflet resections and chordal insertions and transpositions. We, therefore, developed a method to perform in silico annuloplasty where we incrementally reduced the mitral annular area of the diseased mitral valve until we achieved optimal valve closure. Our findings demonstrate that annuloplasty with only moderate annular reduction may be sufficient to achieve optimal coaptation as compared to conventional surgical procedures.
A method to compute the regional strains non-invasively along the mitral annulus has also been developed. Capturing the regional annular strains by echocardiography, may help us predict regional dysfunctions in the mitral annulus, and thus provide information on the pathological mechanisms behind mitral regurgitation. In a study of eight Barlow patients, we observed that on average, the most severe deformation was seen in the posteromedial region. This finding may reveal further insight into the mechanisms of late systolic mitral regurgitation in Barlow’s disease as well as the design of annuloplasty in the future. Moreover, this method may be interesting to deploy on myocardial infarction patients to correlate if annular dysfunction may be a biomarker for the development of secondary mitral regurgitation.