Computational Modeling of Cardiac Valve Function and Intervention

Sun, Wei; Martin, Caitlin; Pham, Thuy M.

doi:10.1146/annurev-bioeng-071813-104517

Cited by 89 publications

(73 citation statements)

References 137 publications

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“…Normal MV function involves a proper, delicate force balance between each of its components throughout the cardiac cycle (Sun et al, 2014). For instance, the chords, which originate from either papillary muscles (on the anterolateral and posterolateral walls) or multiple small muscle bundles attaching to the ventricular wall and insert into the ventricular side of the leaflets, prevent the leaflets from billowing into the left atrium during systole (Sun et al, 2014). …”

Section: Introductionmentioning

confidence: 99%

Characterization of biomechanical properties of aged human and ovine mitral valve chordae tendineae

Zuo

Pham

et al. 2016

Journal of the Mechanical Behavior of Biomedical Materials

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The mitral valve (MV) is a highly complex cardiac valve consisting of an annulus, anterior and posterior leaflets, chordae tendineae (chords) and two papillary muscles. The chordae tendineae mechanics play a pivotal role in proper MV function: the chords help maintain proper leaflet coaptation and rupture of the chordae tendineae due to disease or aging can lead to mitral valve insufficiency. Therefore, the aim of this study was to characterize the mechanical properties of aged human and ovine mitral chordae tendineae. The human and ovine chordal specimens were categorized by insertion location (i.e., marginal, basal and strut) and leaflet type (i.e., anterior and posterior). The results show that human and ovine chords of differing types vary largely in size but do not have significantly different elastic and failure properties. The excess fibrous tissue layers surrounding the central core of human chords added thickness to the chords but did not contribute to the overall strength of the chords. In general, the thinner marginal chords were stiffer than the thicker basal and strut chords, and the anterior chords were stiffer and weaker than the posterior chords. The human chords of all types were significantly stiffer than the corresponding ovine chords and exhibited much lower failure strains. These findings can be explained by the diminished crimp pattern of collagen fibers of the human mitral chords observed histologically. Moreover, the mechanical testing data was modeled with the nonlinear hyperelastic Ogden strain energy function to facilitate accurate computational modeling of the human MV.

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Section: Introductionmentioning

confidence: 99%

Characterization of biomechanical properties of aged human and ovine mitral valve chordae tendineae

Zuo

Pham

et al. 2016

Journal of the Mechanical Behavior of Biomedical Materials

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“…These computational models used a quasi-static approach to simulate valve closure, by applying a static and a uniformly distributed transvalvular pressure directly to the leaflet surface. The 'water hammer' effect caused by dynamic blood flow induced loading of the leaflet cannot be reproduced using a quasi-static method and as a result peak stresses may be underestimated compared to dynamic models [13]. Additionally, assuming a uniformly distributed transvalvular pressure boundary condition may underestimate the impact of stent distortion on leaflet closing mechanics.…”

Section: Introductionmentioning

confidence: 99%

Total ellipse of the heart valve: the impact of eccentric stent distortion on the regional dynamic deformation of pericardial tissue leaflets of a transcatheter aortic valve replacement

Gunning

Saikrishnan

Yoganathan

et al. 2015

J. R. Soc. Interface.

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Transcatheter aortic valve replacements (TAVRs) are a percutaneous alternative to surgical aortic valve replacements and are used to treat patients with aortic valve stenosis. This minimally invasive procedure relies on expansion of the TAVR stent to radially displace calcified aortic valve leaflets against the aortic root wall. However, these calcium deposits can impede the expansion of the device causing distortion of the valve stent and pericardial tissue leaflets. The objective of this study was to elucidate the impact of eccentric TAVR stent distortion on the dynamic deformation of the tissue leaflets of the prosthesis in vitro . Dual-camera stereophotogrammetry was used to measure the regional variation in strain in a leaflet of a TAVR deployed in nominal circular and eccentric (eccentricity index = 28%) orifices, representative of deployed TAVRs in vivo . It was observed that (i) eccentric stent distortion caused incorrect coaptation of the leaflets at peak diastole resulting in a ‘peel-back’ leaflet geometry that was not present in the circular valve and (ii) adverse bending of the leaflet, arising in the eccentric valve at peak diastole, caused significantly higher commissure strains compared with the circular valve in both normotensive and hypertensive pressure conditions (normotension: eccentric = 13.76 ± 2.04% versus circular = 11.77 ± 1.61%, p = 0.0014, hypertension: eccentric = 15.07 ± 1.13% versus circular = 13.56 ± 0.87%, p = 0.0042). This study reveals that eccentric distortion of a TAVR stent can have a considerable impact on dynamic leaflet deformation, inducing deleterious bending of the leaflet and increasing commissures strains, which might expedite leaflet structural failure compared to leaflets in a circular deployed valve.

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Section: Introductionmentioning

confidence: 99%

“…17, 26, 34 In the past several years, significant improvements have been made in MV model fidelity, largely due to advances in imaging technology, segmentation methods, and computational power. 26 Models now aim to simulate MV function with more complex, patient/subject-specific MV geometries in which the finer details and features of the MV are captured. 19, 26, 29 Clinical imaging (3D gated ultrasound, multi-slice computed tomography and magnetic resonance imaging) has been the widely used method of choice for obtaining the patient geometries to create these computational models.…”

Section: Introductionmentioning

confidence: 99%

Ex Vivo Methods for Informing Computational Models of the Mitral Valve

et al. 2016

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Computational modeling of the mitral valve (MV) has potential applications for determining optimal MV repair techniques and risk of recurrent mitral regurgitation. Two key concerns for informing these models are (1) sensitivity of model performance to the accuracy of the input geometry, and, (2) acquisition of comprehensive data sets against which the simulation can be validated across clinically relevant geometries. Addressing the first concern, ex vivo micro-computed tomography (microCT) was used to image MVs at high resolution (~40 micron voxel size). Because MVs distorted substantially during static imaging, glutaraldehyde fixation was used prior to microCT. After fixation, MV leaflet distortions were significantly smaller (p<0.005), and detail of the chordal tree was appreciably greater. Addressing the second concern, a left heart simulator was designed to reproduce MV geometric perturbations seen in vivo in functional mitral regurgitation and after subsequent repair, and maintain compatibility with microCT. By permuting individual excised ovine MVs (n=5) through each state (healthy, diseased and repaired), and imaging with microCT in each state, a comprehensive data set was produced. Using this data set, work is ongoing to construct and validate high-fidelity MV biomechanical models. These models will seek to link MV function across clinically relevant states.

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Computational Modeling of Cardiac Valve Function and Intervention

Cited by 89 publications

References 137 publications

Characterization of biomechanical properties of aged human and ovine mitral valve chordae tendineae

Characterization of biomechanical properties of aged human and ovine mitral valve chordae tendineae

Total ellipse of the heart valve: the impact of eccentric stent distortion on the regional dynamic deformation of pericardial tissue leaflets of a transcatheter aortic valve replacement

Ex Vivo Methods for Informing Computational Models of the Mitral Valve

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