Prosthetic Aortic Heart Valves

Mohammadi, Hadi; Fradet, Guy

doi:10.7243/2052-4358-5-2

Cited by 10 publications

(7 citation statements)

References 37 publications

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“…Eventually, these developments must show an acceptable performance in the actual contact with living blood and in the actual exposure to physiological conditions in short-and long-term studies so that they can be used for the clinical patient care. [24][25][26]…”

Section: Resultsmentioning

confidence: 99%

Proposed percutaneous aortic valve prosthesis made of cryogel

Mohammadi

Goode

Fradet

et al. 2019

Proc Inst Mech Eng H

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Transcatheter heart valves are promising for high-risk patients. Generally, their leaflets are made of pericardium stented in a Nitinol basket. Despite their relative success, they are associated with significant complications such as valve migration, implantation risks, stroke, coronary obstruction, myocardial infraction, acute kidney injury (which all are due to the release of detached solid calcific pieces in to the blood stream) and expected issues existing with tissue valves such as leaflet calcification. This study is an attempt to fabricate the first ever polymeric percutaneous valves made of cryogel following the geometry and mechanical properties of porcine aortic valve to address some of the above-mentioned shortcomings. A novel, one-piece, tricuspid percutaneous valve, consisting of leaflets made entirely from the hydrogel, polyvinyl alcohol cryogel reinforced by bacterial cellulose natural nanocomposite, attached to a Nitinol basket was developed and demonstrated. Following the natural geometry of the valve, a novel approach was applied based on the revolution about an axis of a hyperboloid shape. The geometry was modified based on avoiding sharp warpage of leaflets and removal of the central opening orifice area of the valve when valve is fully closed using the finite element analysis. The modified geometry was replaced by a cloud of (control) points and was essentially converted to Bezier surfaces for further adjustment. A cavity mold was then designed and fabricated to form the valve. The fabricated valve was sewn into the Nitinol basket which is covered by Dacron cloth. The models presented in this study merit further development and revisions for both aortic and mitral positions.

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Section: Resultsmentioning

confidence: 99%

Proposed percutaneous aortic valve prosthesis made of cryogel

Mohammadi

Goode

Fradet

et al. 2019

Proc Inst Mech Eng H

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“…One edge of the model is fixed and the opposite edge is pulled so that it undergoes large deformation. Both coarse mesh (5 3 5) and fine mesh (100 3 100) models were applied and consequently three sets of results can be obtained: (1) the results obtained from the coarse mesh FE model (expected to be highly erroneous), (2) the results obtained from the fine mesh FE model (expected to be accurate), and (3) the results obtained after applying the proposed numerical technique to the erroneous results as shown in Figure 3.…”

Section: Case Study 3 (Two-dimensional Plane Stress Mechanics)mentioning

confidence: 99%

“…Finite element analysis (FEA) has been comprehensively applied for the structural analysis and functional simulation of heart valve (HV) leaflet tissue at a variety of levels. [1][2][3][4][5] Material models utilized in earlier studies for modeling the mechanics of HV leaflet tissue can be typically categorized into two groups of models that have application-dependant accuracy: linear/nonlinear isotropic 6,7 and linear/nonlinear anisotropic. [8][9][10][11] The challenge that occurs with these models is that even for implementations with the highest accuracy, it is still not possible to capture both the tissue composition and structure simultaneously.…”

Section: Introductionmentioning

confidence: 99%

Improving finite element results in modeling heart valve mechanics

Earl

Mohammadi

2018

Proc Inst Mech Eng H

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Finite element analysis is a well-established computational tool which can be used for the analysis of soft tissue mechanics. Due to the structural complexity of the leaflet tissue of the heart valve, the currently available finite element models do not adequately represent the leaflet tissue. A method of addressing this issue is to implement computationally expensive finite element models, characterized by precise constitutive models including high-order and high-density mesh techniques. In this study, we introduce a novel numerical technique that enhances the results obtained from coarse mesh finite element models to provide accuracy comparable to that of fine mesh finite element models while maintaining a relatively low computational cost. Introduced in this study is a method by which the computational expense required to solve linear and nonlinear constitutive models, commonly used in heart valve mechanics simulations, is reduced while continuing to account for large and infinitesimal deformations. This continuum model is developed based on the least square algorithm procedure coupled with the finite difference method adhering to the assumption that the components of the strain tensor are available at all nodes of the finite element mesh model. The suggested numerical technique is easy to implement, practically efficient, and requires less computational time compared to currently available commercial finite element packages such as ANSYS and/or ABAQUS.

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“…The science of blood flow and the mechanics of blood flow is known as hemodynamics. Hemodynamics is a significant element of cardiovascular mechanics and engineering as it simply clarifies the physical laws that direct the bloodstream within the blood vessels [2]. A considerable number of dysfunctions that occur due to cardiovascular diseases and disorders such as hypertension and congestive heart failure are linked to systemic hemodynamics.…”

Section: Introductionmentioning

confidence: 99%

Biomechanics of Human Blood

Earl¹,

Mohammadi²

2019

Biomechanics

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Hematology is known as the study of blood regarding health and disease which revolves around issues with red blood cells (RBCs), white blood cells (WBCs), platelets, lymph nodes, blood vessels, bone marrow, and the proteins involved in bleeding and clotting. As biomedical engineers, it is especially vital to understand the mechanics of the various components of blood to avoid unwanted results from implantations such as heart valves. A comprehensive review on the biomechanics of blood is discussed in this chapter. We will also discuss that even though human blood is a non-Newtonian fluid, depending on the instance, it can be considered a Newtonian fluid.

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Prosthetic Aortic Heart Valves

Cited by 10 publications

References 37 publications

Proposed percutaneous aortic valve prosthesis made of cryogel

Proposed percutaneous aortic valve prosthesis made of cryogel

Improving finite element results in modeling heart valve mechanics

Biomechanics of Human Blood

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