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 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.

Tornado-Compatible Mechanical Aortic Valve Prosthesis: Experimental and Clinical Application of Tornado Technology

2015 ◽  
Author(s):  
Alexander Gorodkov ◽  
Gennady Kiknadze ◽  
Andrey Agafonov ◽  
Shota Zhorzholiany ◽  
Ivan Krestinich ◽  
...  
Keyword(s):  
Exact Solution ◽  
Blood Flow ◽  
Aortic Valve ◽  
Left Ventricle ◽  
Flow Pattern ◽  
Heart Valve ◽  
Anticoagulation Therapy ◽  
Prosthetic Heart Valve ◽  
Valve Prosthesis ◽  
Mechanical Aortic Valve

Currently used mechanical heart valve prostheses does not fully restore the function of the valve and require aggressive anticoagulation therapy. One of the reasons leading to the prostheses disfunction is neglecting of hydrodynamic compatibility with the blood flow pattern Studies of the hydrodynamic structure of the blood flow in the heart and aorta are being performed in the Bakulev Center for Cardiovascular surgery since 1992. It has been shown that blood flow, generated in the left ventricle corresponds to the structure of self-organizing tornado-like flows described by the exact solution of unsteady hydrodynamic equations for this class of flows, published in 1986. The previous attempts to adapt the geometry of prosthetic heart valve to the swirling blood flow were not successful since there were no any quantitative criteria of the flow structere. A new model of a mechanical aortic valve — Tornado-compatible valve (TCV) (patent RU 2434604 C1), has the lumen completely free from any kind of obstacles that could disrupt the flow pattern. The valve consists of a body and three cusps which profile is adopted both to the flow in Aorta, and to the flow in Sinuses when the valve is closed. The standard hydrodynamic testing of this valve has shown its significant advantage compared with other valve types. A special testing was developed using the original bench which generates the Tornado-like jet. For this a converging channel was worked out, which profile corresponds to the streamlines of Tornado-like flow, calculated from the exact solution. The resulted jet manifested all principal properties of Tornado: laminar “glass-transparent” jet without any visible perturbations in the flow core. Several valve types were testing using this bench. TCV did not affected the jet structure, and time of water flowing out. The valve was implanted in the pig without anticoagulant administration. According to echocardiography and coagulation control the valve function was satisfactory up to ten months of observation. In the autopsy the luminal surface of outflow part of the left ventricle, and the ascending aorta were free of thrombi and pannus formation. The clinical implantation in the patient with aortic stenosis was performed. The follow-up period is 4 years.

scholarly journals Experimental substantiation of the design of a prosthetic heart valve for «valve-in-valve» implantation

2017 ◽  
Vol 19 (2) ◽  
pp. 69-77
Author(s):  
K. Yu. Klyshnikov ◽  
E. A. Ovcharenko ◽  
A. N. Stasev ◽  
T. V. Glushkova ◽  
Yu. A. Kudryavtseva ◽  
...  
Keyword(s):  
Heart Valve ◽  
Prosthetic Heart Valve ◽  
Hydrodynamic Characteristics ◽  
Implantation Technique ◽  
Effective Orifice Area ◽  
Test Machine ◽  
Critical Surface ◽  
Valve Prosthesis ◽  
Valve In Valve ◽  
Valve Implantation

The aim of the study was to perform a series of in vitro tests of a prototype of the developing heart valve prosthesis to evaluate its functional characteristics. Materials and methods. In this work we have used the frames and full prototypes of the prosthesis, consisting of a stent-like stainless steel support frame with mounted biological leaflets and cover. The authors evaluated the calculated and experimental forces necessary for the displacement of the sutureless implanted prosthesis using the test machine under uniaxial tension. The risk of defects and damages to the supporting framework as a result of implantation was evaluated by scanning electron microscopy. The hydrodynamic characteristics of the prosthesis were investigated under physiological conditions and «valvein-valve» implantation. Evaluation of the ergonomics and applicability of the proposed construction on the cadaver heart model of cattle was carried out. Results. As a result of the forces assessment, it was found that the force required to shear the prosthesis was 3.12 ± 0.37 N, while the calculated value was 1.7 N, which is significantly lower than the obtained value. The comparison of the images obtained with small and large magnifications demonstrated the absence of critical surface defects. Additional analysis under the super-large magnifications also did not reveal problem areas. During the hydrodynamic study, it was shown that the average transplant gradient increased slightly from 2.8–3.4 to 3.2–4.5 mm Hg for the initial prosthesis and the «valve-in-valve» complex, respectively. The decrease of the effective orifice area was 6–9% relative to the initial one. Evaluation of the implantation technique demonstrated the consistency of the approach: the use of the developed holder in combination with the balloon implantation system made it possible to position the prosthesis throughout the procedure. Conclusion. The series of tests demonstrates the consistency of the developed design, intended for the replacement of a failed prosthetic valve of the heart with the «valve-in-valve» implantation.

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.

scholarly journals FLOW CHARACTERISTICS OF THE MENISCUS PROSTHETIC HEART VALVE

1965 ◽  
Vol 49 (5) ◽  
pp. 813-817 ◽  
Author(s):  
Anatolio B. Cruz ◽  
Robert L. Kaster ◽  
Robert L. Simmons ◽  
Luc Bruneau ◽  
C. Walton Lillehei
Keyword(s):  
Heart Valve ◽  
Prosthetic Heart Valve ◽  
Flow Characteristics

scholarly journals Aortic Root Enlargement in patients with small aortic annulus undergoing double valve replacement. A retrospective Comparative cohort study

2020 ◽  
Author(s):  
Yasser Shaban Mubarak ◽  
Ahmed Abdel Rahman Abdeljawad
Keyword(s):  
Aortic Valve ◽  
Valve Replacement ◽  
Aortic Root ◽  
Aortic Pressure ◽  
Aortic Annulus ◽  
Paravalvular Leak ◽  
Double Valve Replacement ◽  
Small Aortic Annulus ◽  
Aortic Root Enlargement

Abstract Objectives Small Aortic Annulus (AA) is big issue during Aortic Valve Replacement (AVR) necessitating replacement of inappropriate-sized prostheses especially during Double Valve Replacement (DVR). Despite that small aortic valve prostheses can lead to Prosthesis-Patient Mismatch (PPM), there remains reluctance to perform aortic root enlargement (ARE) procedures fearing from morbidity and mortality. We evaluate clinical and echocardiographic outcomes in patients with small AA undergoing DVR. Methods The study included 100 consecutive patients underwent DVR for combined rheumatic aortic and mitral valve diseases, between June 2016 and November 2020. Only (50) patients had ARE with DVR. ARE was performed using an autologous or bovine pericardium or Dacron patch by Nick′s or Manouguian procedures. The estimated post-operative end-points were mortality, effective orifice areas (EOA), mean aortic pressure gradient and valve-related complications. The least post-operative follow-up period was 6 months. Results The study included 30 male and 70 female patients with mean age of 45 ± 10 years, body surface area (BSA) of 1.6 ± 0.50 m2, aortic annulus diameter was 20 ± 0.4 mm, EOAi was 0.80 ± 0.50 cm2/m2, and aortic mean gradient (PG) 80 ± 40 mm Hg. During follow-up period, there was a mild paravalvular leak (1%) with, (1%) heart block, and residual mean PG on prosthetic aortic valve with all cases of DVR alone. Conclusion Enlargement of aortic root by Nick′s or Manouguian technique is safe and effective in patients with small aortic annulus undergoing double valve replacements.

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