The important roles of tissue anisotropy and tissue-to-tissue contact on the dynamical behavior of a symmetric tri-leaflet valve during multiple cardiac pressure cycles

Saleeb, A. F.; Kumar, Akhilesh; Thomas, Vineet S.

doi:10.1016/j.medengphy.2012.03.006

Cited by 21 publications

(18 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The collagen network is described as an angular distribution of collagen fibers. In other studies, the tissue has also been approximated as an orthotropic material (Burriesci et al, 1999;Li et al, 2001;Saleeb et al, 2012). However, using a distribution of fiber directions is more realistic as the rotation of fibers and thereby the complex interaction between the circumferential and radial direction is accounted for (Billiar and Sacks, 2000a,b).…”

Section: Discussionmentioning

confidence: 99%

Effects of Valve Geometry and Tissue Anisotropy on the Radial Stretch and Coaptation Area of Tissue-Engineered Heart Valves

Loerakker

Argento

Oomens

et al. 2013

Volume 1A: Abdominal Aortic Aneurysms; Active and Reactive Soft Matter; Atherosclerosis; BioFluid Mechanics; Education; Biotran

View full text Add to dashboard Cite

Tissue engineering represents a promising technique to overcome the limitations of the current valve replacements, since it allows for creating living autologous heart valves that have the potential to grow and remodel. However, also this approach still faces a number of challenges. One particular problem is regurgitation, caused by cell-mediated tissue retraction or the mismatch in geometrical and material properties between tissue-engineered heart valves (TEHVs) and their native counterparts. The goal of the present study was to assess the influence of valve geometry and tissue anisotropy on the deformation profile and closed configuration of TEHVs. To achieve this aim, a range of finite element models incorporating different valve shapes was developed, and the constitutive behavior of the tissue was modeled using an established computational framework, where the degree of anisotropy was varied between values representative of TEHVs and native valves. The results of this study suggest that valve geometry and tissue anisotropy are both important to maximize the radial strains and thereby the coaptation area. Additionally, the minimum degree of anisotropy that is required to obtain positive radial strains was shown to depend on the valve shape and the pressure to which the valves are exposed. Exposure to pulmonary diastolic pressure only yielded positive radial strains if the anisotropy was comparable to the native situation, whereas considerably less anisotropy was required if the valves were exposed to aortic diastolic pressure. AbstractTissue engineering represents a promising technique to overcome the limitations of the current valve replacements, since it allows for creating living autologous heart valves that have the potential to grow and remodel. However, also this approach still faces a number of challenges. One particular problem is regurgitation, caused by cell-mediated tissue retraction or the mismatch in geometrical and material properties between tissue-engineered heart valves (TEHVs) and their native counterparts. The goal of the present study was to assess the influence of valve geometry and tissue anisotropy on the deformation profile and closed configuration of TEHVs. To achieve this aim, a range of finite element models incorporating different valve shapes was developed, and the constitutive behavior of the tissue was modeled using an established computational framework, where the degree of anisotropy was varied between values representative of TEHVs and native valves. The results of this study suggest that valve geometry and tissue anisotropy are both important to maximize the radial strains and thereby the coaptation area. Additionally, the minimum degree of anisotropy that is required to obtain positive radial strains was shown to depend on the valve shape and the pressure to which the valves are exposed. Exposure to pulmonary diastolic pressure only yielded positive radial strains if the anisotropy was comparable to the native situation, whereas considerably less anisotropy was ...

show abstract

Section: Discussionmentioning

confidence: 99%

Effects of Valve Geometry and Tissue Anisotropy on the Radial Stretch and Coaptation Area of Tissue-Engineered Heart Valves

Loerakker

Argento

Oomens

et al. 2013

Volume 1A: Abdominal Aortic Aneurysms; Active and Reactive Soft Matter; Atherosclerosis; BioFluid Mechanics; Education; Biotran

View full text Add to dashboard Cite

show abstract

“…[106]), and we therefore suspect that it is highly sensitive to valve geometry, leaflet material properties, and flow conditions. It seems unlikely that a uniform pressure follower load would cause this closing behavior, and it is not seen in any of the earlier structural dynamics computations of [9, 31, 101]. …”

Section: Bhv Simulationsmentioning

confidence: 99%

“…The use of pinned rather than clamped boundary conditions is common in the structural analysis of BHVs reported previously [9, 31, 99–101]. However, the leaflets are, in fact, physically clamped at the attachment edge in most stented BHVs (see, e.g., [102, 103]).…”

Section: Bhv Simulationsmentioning

confidence: 99%

“…In Section 3, we construct a discrete model of a BHV immersed in the lumen of a flexible artery and apply the methodology of Section 2 to perform a BHV FSI simulation. We compare the FSI results with the results of a standalone structural dynamics BHV simulation driven by prescribed transvalvular pressure, considered to be “state-of-the-art” in the biomechanics community [9]. Section 4 draws conclusions.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Dynamic and fluid–structure interaction simulations of bioprosthetic heart valves using parametric design with T-splines and Fung-type material models

et al. 2015

View full text Add to dashboard Cite

This paper builds on a recently developed immersogeometric fluid–structure interaction (FSI) methodology for bioprosthetic heart valve (BHV) modeling and simulation. It enhances the proposed framework in the areas of geometry design and constitutive modeling. With these enhancements, BHV FSI simulations may be performed with greater levels of automation, robustness and physical realism. In addition, the paper presents a comparison between FSI analysis and standalone structural dynamics simulation driven by prescribed transvalvular pressure, the latter being a more common modeling choice for this class of problems. The FSI computation achieved better physiological realism in predicting the valve leaflet deformation than its standalone structural dynamics counterpart.

show abstract

“…Many decoupled finite element (FE) and computational fluid dynamics (CFD) simulations have been performed to investigate valve leaflet dynamics (Kim et al 2008; Koch et al 2010; Li and Sun 2010; Loerakker et al 2013; Mohammadi et al 2009; Morganti et al 2015; Saleeb et al 2013; Sun et al 2010), however, structural responses and hemodynamics of a BHV cannot be accurately evaluated using either FE models or CFD models alone due to strong coupling effects between the blood flow and very flexible and stretchable leaflets. In recent years, FSI simulations of BHV opening and closing dynamics have been actively pursued (Marom 2014).…”

Section: Introductionmentioning

confidence: 99%

Fluid–Structure Interaction Study of Transcatheter Aortic Valve Dynamics Using Smoothed Particle Hydrodynamics

Mao

Sun

2016

Cardiovasc Eng Tech

View full text Add to dashboard Cite

Computational modeling of heart valve dynamics incorporating both fluid dynamics and valve structural responses has been challenging. In this study, we developed a novel fully-coupled fluid-structure interaction (FSI) model using smoothed particle hydrodynamics (SPH). A previously developed nonlinear finite element (FE) model of transcatheter aortic valves (TAV) was utilized to couple with SPH to simulate valve leaflet dynamics throughout the entire cardiac cycle. Comparative simulations were performed to investigate the impact of using FE-only models versus FSI models, as well as an isotropic versus an anisotropic leaflet material model in TAV simulations. From the results, substantial differences in leaflet kinematics between FE-only and FSI models were observed, and the FSI model could capture the realistic leaflet dynamic deformation due to its more accurate spatial and temporal loading conditions imposed on the leaflets. The stress and the strain distributions were similar between the FE and FSI simulations. However, the peak stresses were different due to the water hammer effect induced by the flow inertia in the FSI model during the closing phase, which led to 13%–28% lower peak stresses in the FE-only model compared to that of the FSI model. The simulation results also indicated that tissue anisotropy had a minor impact on hemodynamics of the valve. However, a lower tissue stiffness in the radial direction of the leaflets could reduce the leaflet peak stress caused by the water hammer effect. It is hoped that the developed FSI models can serve as an effective tool to better assess valve dynamics and optimize next generation TAV designs.

show abstract

The important roles of tissue anisotropy and tissue-to-tissue contact on the dynamical behavior of a symmetric tri-leaflet valve during multiple cardiac pressure cycles

Cited by 21 publications

References 39 publications

Effects of Valve Geometry and Tissue Anisotropy on the Radial Stretch and Coaptation Area of Tissue-Engineered Heart Valves

Effects of Valve Geometry and Tissue Anisotropy on the Radial Stretch and Coaptation Area of Tissue-Engineered Heart Valves

Dynamic and fluid–structure interaction simulations of bioprosthetic heart valves using parametric design with T-splines and Fung-type material models

Fluid–Structure Interaction Study of Transcatheter Aortic Valve Dynamics Using Smoothed Particle Hydrodynamics

Contact Info

Product

Resources

About