scholarly journals Numerical simulation of a transcatheter aortic heart valve under application-related loading

2018 ◽  
Vol 4 (1) ◽  
pp. 185-189
Author(s):  
Sylvia Pfensig ◽  
Sebastian Kaule ◽  
Robert Ott ◽  
Carolin Wüstenhagen ◽  
Michael Stiehm ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Aortic Valve ◽  
Minimally Invasive ◽  
Heart Valve ◽  
Aortic Root ◽  
Constitutive Law ◽  
Ar Model ◽  
Valve Prosthesis ◽  
Target Region ◽  
Opening And Closing

AbstractFor the treatment of severe symptomatic aortic valve stenosis, minimally invasive heart valve prostheses have more recently become the lifesaving solution for elderly patients with high operational risk and thus, are often implanted in patients with challenging aortic root configuration. A correct prosthesis deployment and stent adaption to the target region is essential to ensure optimal leaflet performance and long-term prosthesis function. The objective of this study was the development of a suitable in silico setup for structural numerical simulation of a transcatheter aortic valve (TAV) in different cases of clinical relevance. A transcatheter valve prosthesis comprising an unpressurized trileaflet heart valve and an adapted stent configuration was designed. An aortic root (AR) model was developed, based on microcomputed tomography of a native healthy specimen. Using the finite-element analysis (FEA), various loading cases including prosthesis biomechanics with valve opening and closing under physiological pressure ratios throughout a cardiac cycle, prosthesis crimping as well as crimping and release into the developed AR model were simulated. Hyperelastic constitutive law for polymeric leaflet material and superelasticity of shape memory alloys for the self-expanding Nitinol stent structure were implemented into the FEA setup. Calculated performance of the valve including the stent structure demonstrated enhanced leaflet opening and closing as a result of stent deformation and redirected loading. Crimping and subsequent release into the AR model as well as the stent adaption to the target region after expansion proved the suitability of the TAV design for percutaneous application. FEA represented a useful tool for numerical simulation of an entire minimally invasive heart valve prosthesis in relevant clinical scenarios.

The Influence of the Aortic Root Geometry on Flow Characteristics of a Prosthetic Heart Valve

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Oleksandr Barannyk ◽  
Peter Oshkai
Keyword(s):  
Aortic Valve ◽  
Heart Valve ◽  
Aortic Root ◽  
Reynolds Shear Stress ◽  
Prosthetic Heart Valve ◽  
Flow Characteristics ◽  
Aortic Pressure ◽  
Valve Prosthesis ◽  
Aortic Heart Valve ◽  
Valve Diseases

In this paper, performance of aortic heart valve prosthesis in different geometries of the aortic root is investigated experimentally. The objective of this investigation is to establish a set of parameters, which are associated with abnormal flow patterns due to the flow through a prosthetic heart valve implanted in the patients that had certain types of valve diseases prior to the valve replacement. Specific valve diseases were classified into two clinical categories and were correlated with the corresponding changes in aortic root geometry while keeping the aortic base diameter fixed. These categories correspond to aortic valve stenosis and aortic valve insufficiency. The control case that corresponds to the aortic root of a patient without valve disease was used as a reference. Experiments were performed at test conditions corresponding to 70 beats/min, 5.5 L/min target cardiac output, and a mean aortic pressure of 100 mmHg. By varying the aortic root geometry, while keeping the diameter of the orifice constant, it was possible to investigate corresponding changes in the levels of Reynolds shear stress and establish the possibility of platelet activation and, as a result of that, the formation of blood clots.

In Vitro Study of the Influence of the Aortic Root Geometry on Flow Characteristics of a Prosthetic Heart Valve

2013 ◽  
Author(s):  
Oleksandr Barannyk ◽  
Satya Karri ◽  
Peter Oshkai
Keyword(s):  
Aortic Valve ◽  
Heart Valve ◽  
Aortic Root ◽  
Reynolds Shear Stress ◽  
Prosthetic Heart Valve ◽  
Flow Characteristics ◽  
In Vitro Study ◽  
Valve Prosthesis ◽  
Valve Diseases

In this paper, performance of aortic heart valve prosthesis in different geometries of the aortic root is investigated experimentally. The objective of this investigation is to establish a set of parameters, which are associated with abnormal flow patterns due to the flow through a prosthetic heart valve implanted to the patients that had certain types of valve diseases prior to the valve replacement. Specific valve diseases, classified into two clinical categories, were correlated with the corresponding changes of aortic root geometry. These categories correspond to aortic valve stenosis and aortic valve insufficiency. The control case that corresponds to the aortic root of a patient without valve disease was used as a reference. Experiments were performed at test conditions corresponding to 70 beats/min, 5.5 L/min target cardiac output and a mean aortic pressure of 100 mmHg. By varying the aortic root geometry, it was possible to investigate corresponding changes in the levels of Reynolds shear stress and establish the possibility of platelet activation and, as a result of that, the formation of blood clots.

scholarly journals Assessment of heart valve performance by finite-element design studies of polymeric leaflet-structures

2017 ◽  
Vol 3 (2) ◽  
pp. 631-634
Author(s):  
Sylvia Pfensig ◽  
Sebastian Kaule ◽  
Michael Sämann ◽  
Michael Stiehm ◽  
Niels Grabow ◽  
...  
Keyword(s):  
Finite Element ◽  
Minimally Invasive ◽  
Heart Valve ◽  
Constitutive Law ◽  
Uniaxial Tensile ◽  
Valve Prosthesis ◽  
Design Studies ◽  
Heart Valve Prostheses ◽  
Valve Prostheses

AbstractFor the treatment of severe symptomatic aortic valve stenosis, minimally invasive heart valve prostheses are increasingly used, especially for elderly patients. The current generation of devices is based on xenogenic leaflet material, involving limitations with regard to calcification and durability. Artificial polymeric leaflet-structures re-present a promising approach for improvement of valve performance. Within the current work, finite-element ana-lysis (FEA) design studies of polymeric leaflet structures were conducted. Design of an unpressurized and axially-symmetric trileaflet heart valve was developed based on nine parameters. Physiological pressurization in FEA was specified, based on in vitro hydrodynamic testing of a commercially available heart valve prosthesis. Hyper-elastic constitutive law for polymeric leaflet material was implemented based on experimental stress strain curves resulting from uniaxial tensile and planar shear testing. As a result of FEA, time dependent leaflet deformation of the leaflet structure was calculated. Obtained leaflet dynamics were comparable to in vitro performance of the analyzed prosthesis. As a major design parameter, the lunula angle has demonstrated crucial influence on the performance of the polymeric leaflet structures. FEA represented a useful tool for design of improved polymeric leaflet structures for minimally invasive implantable heart valve prostheses.

Minimally invasive redo aortic valve replacement with a sutureless valve implant

2021 ◽  
Keyword(s):  
Aortic Valve ◽  
Aortic Valve Replacement ◽  
Minimally Invasive ◽  
Valve Replacement ◽  
Valve Prosthesis ◽  
Mechanical Prosthesis ◽  
Invasive Approach ◽  
Replacement Procedure ◽  
Aortic Valve Prosthesis ◽  
Sutureless Valve

Reoperations for a dysfunctional mechanical aortic valve prosthesis are usually performed with a repeat sternotomy. Reopening the chest may be associated with a heart structure tear, bleeding, excessive transfusion, and a possible unfavorable outcome. Experience performing a redo aortic valve replacement with a minimally invasive approach and avoiding lysis of the pericardial adhesions is growing. We describe a redo aortic valve replacement procedure performed because of subvalvular pannus formation in a patient with a mechanical prosthesis. A partial J-shaped hemisternotomy at the 3rd intercostal space was performed; the ascending aorta was exposed and the valve was replaced with a sutureless bioprosthesis. The video tutorial shows the surgical approach, cardiopulmonary bypass solutions, and sutureless valve deployment.

scholarly journals Fluid-structure interaction of heart valve dynamics in comparison to finite-element analysis

2018 ◽  
Vol 4 (1) ◽  
pp. 259-262 ◽  
Author(s):  
Finja Borowski ◽  
Michael Sämann ◽  
Sylvia Pfensig ◽  
Carolin Wüstenhagen ◽  
Robert Ott ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Heart Valve ◽  
Elastic Behavior ◽  
Valve Prosthesis ◽  
Arbitrary Lagrangian Eulerian ◽  
Element Analysis ◽  
Valve Dynamics ◽  
Valve Opening ◽  
Valve Prostheses

AbstractAn established therapy for aortic valve stenosis and insufficiency is the transcatheter aortic valve replacement. By means of numerical simulation the valve dynamics can be investigated to improve the valve prostheses performance. This study examines the influence of the hemodynamic properties on the valve dynamics utilizing fluidstructure interaction (FSI) compared with results of finiteelement analysis (FEA). FEA and FSI were conducted using a previously published aortic valve model combined with a new developed model of the aortic root. Boundary conditions for a physiological pressurization were based on measurements of ventricular and aortic pressure from in vitro hydrodynamic studies of a commercially available heart valve prosthesis using a pulse duplicator system. A linear elastic behavior was assumed for leaflet material properties and blood was specified as a homogeneous, Newtonian incompressible fluid. The type of fluid domain discretization can be described with an arbitrary Lagrangian-Eulerian formulation. Comparison of significant points of time and the leaflet opening area were used to investigate the valve opening behavior of both analyses. Numerical results show that total valve opening modelled by FEA is faster compared to FSI by a factor of 5. In conclusion the inertia of the fluid, which surrounds the valve leaflets, has an important influence on leaflet deformation. Therefore, fluid dynamics should not be neglected in numerical analysis of heart valve prostheses.

On-X Heart Valve Prosthesis: Numerical Simulation of Hemodynamic Performance in Accelerating Systole

2016 ◽  
Vol 7 (3) ◽  
pp. 223-237 ◽  
Author(s):  
Nima Mirkhani ◽  
Mohammad Reza Davoudi ◽  
Pedram Hanafizadeh ◽  
Daryoosh Javidi ◽  
Niloofar Saffarian
Keyword(s):  
Numerical Simulation ◽  
Heart Valve ◽  
Heart Valve Prosthesis ◽  
Valve Prosthesis ◽  
Hemodynamic Performance

Results of mechanical versus tissue AVR: caution in young patients with tissue AVR

Heart ◽  
2019 ◽  
Vol 105 (Suppl 2) ◽  
pp. s34-s37
Author(s):  
Norman Paul Briffa
Keyword(s):  
Aortic Valve ◽  
Heart Valve ◽  
Mechanical Heart Valve ◽  
Young Patients ◽  
Patient Choice ◽  
Heart Valve Disease ◽  
Valve Prosthesis ◽  
Younger Patients ◽  
Mechanical Prostheses ◽  
Aortic Valve Prosthesis

The first aortic valve prosthesis, implanted more than 50 years ago, was a mechanical prosthesis (ball-and-cage design). Over the ensuing decades, tissue prostheses and new mechanical designs were introduced to mitigate the need for anticoagulation with its associated side effects. Tissue and mechanical heart valve prostheses were compared in two head-to-head randomised control trials. Both of these confirmed that mechanical prostheses were durable but patients suffered anticoagulant-related bleeds. Patients who received a tissue prosthesis were more likely to suffer prosthetic dysfunction and require reoperation. This trend was stronger in younger patients. Since the publication of those two trials, several large retrospective studies using data from meta-analyses of published papers or registries have failed to show a survival advantage of either prostheses when implanted in the aortic position in younger patients. This equipoise has been reflected in the heart valve disease guidelines published by European and US societies. In recent years, the primacy of patient choice, the rapid increase in life expectancy of populations, the increased incidence of atrial fibrillation with requirement for anticoagulation, the advent of transcatheter techniques to treat degenerating tissue valves as well as advances in anticoagulant therapy and in new tissue and to a lesser extent mechanical prosthetic design continue to influence choice of aortic valve prosthesis in younger patients undergoing aortic valve replacement.

Blood flow of MHD non-Newtonian nanofluid with heat transfer and slip effects

2020 ◽  
Vol 30 (11) ◽  
pp. 4883-4908 ◽  
Author(s):  
Asmaa F. Elelamy ◽  
Nasser S. Elgazery ◽  
R. Ellahi
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Numerical Simulation ◽  
Mathematical Model ◽  
Blood Flow ◽  
Heart Valve ◽  
Vascular Resistance ◽  
Bacterial Growth ◽  
Valve Prosthesis ◽  
Content Type

Purpose This paper aims to investigate a mathematical model with numerical simulation for bacterial growth in the heart valve. Design/methodology/approach For antibacterial activities and antibodies properties, nanoparticles have been used. As antibiotics are commonly thought to be homogeneously dispersed through the blood, therefore, non-Newtonian fluid of Casson micropolar blood flow in the heart valve for two dimensional with variable properties is used. The heat transfer with induced magnetic field translational attraction under the influence of slip is considered for the resemblance of the heart valve prosthesis. The numeral results have been obtained by using the Chebyshev pseudospectral method. Findings It is proven that vascular resistance decreases for increasing blood velocity. It is noted that when the magnetic field will be induced from the heart valve prosthesis then it may cause a decrease in vascular resistance. The unbounded molecules and antibiotic concentration that are able to penetrate the bacteria are increased by increasing values of vascular resistance. The bacterial growth density cultivates for upswing values of magnetic permeability and magnetic parameters. Originality/value To the best of the authors’ knowledge, this is the first study to investigate a mathematical model with numerical simulation for bacterial growth in the heart valve.

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