Emerging Trends in Heart Valve Engineering: Part IV. Computational Modeling and Experimental Studies

Dysfunction of mitral valve causes morbidity and premature mortality and remains a leading medical problem worldwide. Computational modelling aims to understand the biomechanics of human mitral valve and could lead to the development of new treatment, prevention and diagnosis of mitral valve diseases. Compared with the aortic valve, the mitral valve has been much less studied owing to its highly complex structure and strong interaction with the blood flow and the ventricles. However, the interest in mitral valve modelling is growing, and the sophistication level is increasing with the advanced development of computational technology and imaging tools. This review summarises the state‐of‐the‐art modelling of the mitral valve, including static and dynamics models, models with fluid‐structure interaction, and models with the left ventricle interaction. Challenges and future directions are also discussed.

Section: Validation and Verificationmentioning

confidence: 99%

Modelling mitral valvular dynamics–current trend and future directions

Gao

Feng

et al. 2017

“…Such complex FSI computations however require further validation and thus need to be supported by experimental data, as pointed out before. One difficulty regarding the validation of solvers dedicated to aortic valve applications is the diversity of challenges met: (1) The geometry and the flow are complex; (2) there are FSIs between the valve leaflets and the blood; (3) the Reynolds number is sufficiently high to yield turbulence transition or at least intermittency; (4) the aorta is deformable; (5) blood and valves (either native or bioprosthetic valves) are biological materials whose characterization is far from trivial …”

Section: Introductionmentioning

confidence: 99%

“…[25][26][27][28][29] Such models however need to be supported by experimental data to establish the validity and reliability of the numerical results. Nonetheless, as pointed out by Kheradvar et al, 30 there are still very few experimental validations of FSI valve models regarding flexible native or prosthetic aortic valves. Two main limitations are highlighted by Kheradvar et al 30 : the ability of FSI valve models to perform multiple cardiac cycles, probably due to the high computational cost of such FSI computations, and the difficulty to simulate the contact between the thin deformable leaflets when the valve is fully closed.…”

Section: Introductionmentioning

confidence: 99%

“…One difficulty regarding the validation of solvers dedicated to aortic valve applications is the diversity of challenges met: (1) The geometry and the flow are complex; (2) there are FSIs between the valve leaflets and the blood; (3) the Reynolds number is sufficiently high to yield turbulence transition or at least intermittency; (4) the aorta is deformable; (5) blood and valves (either native or bioprosthetic valves) are biological materials whose characterization is far from trivial. 30,32 In the present study, experimental data are generated thanks to a bio-inspired experimental test rig which attempts to mimic the interaction of the blood flow with the aortic valve, namely, a pulsatile flow driving a model of aortic valve to alternatively open and close at a moderate Reynolds number. It must however be emphasized that such a configuration does not attempt to perfectly reproduce the physiological flow conditions which the aortic valve is subjected to, neither to faithfully model the anisotropic and nonlinear material properties of the aortic valve tissue nor the non-Newtonian behavior of the blood.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Fluid‐structure interaction of a pulsatile flow with an aortic valve model: A combined experimental and numerical study

Sigüenza

Pott

Mendez

et al. 2018

The complex fluid-structure interaction problem associated with the flow of blood through a heart valve with flexible leaflets is investigated both experimentally and numerically. In the experimental test rig, a pulse duplicator generates a pulsatile flow through a biomimetic rigid aortic root where a model of aortic valve with polymer flexible leaflets is implanted. High-speed recordings of the leaflets motion and particle image velocimetry measurements were performed together to investigate the valve kinematics and the dynamics of the flow. Large eddy simulations of the same configuration, based on a variant of the immersed boundary method, are also presented. A massively parallel unstructured finite-volume flow solver is coupled with a finite-element solid mechanics solver to predict the fluid-structure interaction between the unsteady flow and the valve. Detailed analysis of the dynamics of opening and closure of the valve are conducted, showing a good quantitative agreement between the experiment and the simulation regarding the global behavior, in spite of some differences regarding the individual dynamics of the valve leaflets. A multicycle analysis (over more than 20 cycles) enables to characterize the generation of turbulence downstream of the valve, showing similar flow features between the experiment and the simulation. The flow transitions to turbulence after peak systole, when the flow starts to decelerate. Fluctuations are observed in the wake of the valve, with maximum amplitude observed at the commissure side of the aorta. Overall, a very promising experiment-vs-simulation comparison is shown, demonstrating the potential of the numerical method.

“…Yet isolating the effect of each factor to study the valvular response is not feasible either in vitro or in vivo animal studies. On the other hand, computational simulations of heart valve behavior have proven to be promising tools to enhance our understanding of the valvular mechanisms and response to pathological alterations . However, existing computational models have yet to account for all the underlying features that impact the MV behavior.…”

Section: Introductionmentioning

confidence: 99%

A comprehensive pipeline for multi‐resolution modeling of the mitral valve: Validation, computational efficiency, and predictive capability

Drach

Khalighi

Sacks

2017

Multiple studies have demonstrated that the pathological geometries unique to each patient can affect the durability of mitral valve (MV) repairs. While computational modeling of the MV is a promising approach to improve the surgical outcomes, the complex MV geometry precludes use of simplified models. Moreover, the lack of complete in-vivo geometric information presents significant challenges in the development of patient-specific computational models. There is thus a need to determine the level of detail necessary for predictive MV models. To address this issue, we have developed a novel pipeline for building attribute-rich computational models of MV with varying fidelity directly from the in-vitro imaging data. The approach combines high-resolution geometric information from loaded and unloaded states to achieve a high level of anatomic detail, followed by mapping and parametric embedding of tissue attributes to build a high resolution, attribute-rich computational models. Subsequent lower resolution models were then developed, and evaluated by comparing the displacements and surface strains to those extracted from the imaging data. We then identified the critical levels of fidelity for building predictive MV models in the dilated and repaired states. We demonstrated that a model with a feature size of ~5 mm and mesh size of ~1 mm was sufficient to predict the overall MV shape, stress, and strain distributions with high accuracy. However, we also noted that more detailed models were found to be needed to simulate microstructural events. We conclude that the developed pipeline enables sufficiently complex models for biomechanical simulations of MV in normal, dilated, repaired states.