scholarly journals Transient Study of Flow and Cavitation Inside a Bileaflet Mechanical Heart Valve

2020 ◽  
Vol 10 (7) ◽  
pp. 2548 ◽  
Author(s):  
Wen-qing Li ◽  
Zhi-xin Gao ◽  
Zhi-jiang Jin ◽  
Jin-yuan Qian
Keyword(s):  
Heart Valve ◽  
High Speed ◽  
Heart Valves ◽  
High Reliability ◽  
Mechanical Heart Valve ◽  
Water Hammer ◽  
Leakage Flow ◽  
Total Period ◽  
Flow Effect ◽  
Bileaflet Mechanical Heart Valve

A mechanical heart valve (MHV) is an effective device to cure heart disease, which has the advantage of long life and high reliability. Due to the hemodynamic characteristics of blood, mechanical heart valves can lead to potential complications such as hemolysis, which have damage to the blood elements and thrombosis. In this paper, flowing features of the blood in the valve are analyzed and the cavitation mechanism in bileaflet mechanical heart valve (BMHV) is studied. Results show that the water hammer effect and the high-speed leakage flow effect are the primary causes of the cavitation in the valve. Compared with the high-speed leakage flow effect, the water hammer has a greater effect on the cavitation strength. The valve goes through four kinds of working condition within one heart beating period, including, fully opening stage, closing stage and fully closing stage. These four stages, respectively, make up 8.5%, 16.1%, 4.7% and 70.7% of the total period. The cavitation occurs on the fully closing stage. When the valve is in closing stage, the high pressure downstream of the valve lasts for about 20 ms and the high-speed leakage flow lasts for about 200 ms. This study systematically analyzes the causes of cavitation emerged in the process of periodic motion, which proposes the method for characterizing the intensity of the cavitation, and can be referred to for the cavitation suppression of the BHMV and similar valves.

scholarly journals Stereoscopic PIV of Steady Flow Through a Bileaflet Mechanical Heart Valve

2008 ◽  
Author(s):  
C. Hutchison ◽  
P. E. Sullivan ◽  
C. R. Ethier
Keyword(s):  
Steady Flow ◽  
Heart Valve ◽  
Heart Valves ◽  
Mechanical Heart Valve ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Shear Stresses ◽  
Stereoscopic Piv ◽  
Bileaflet Mechanical Heart Valve ◽  
Component Particle

Each year over 180,000 mechanical heart valves are implanted worldwide, with the bileaflet mechanical heart valve (BiMHV) accounting for approximately 85% of all valve replacements [1,2]. Although much improved from previous valve designs, aortic BiMHV design is far from ideal, and serious complications such as thromboembolism and hemolysis often result. Hemolysis and platelet activation are thought to be caused by turbulent Reynolds shear stresses in the flow [1]. Numerous previous studies have examined aortic BiMHV flow using LDA and two component Particle Image Velocimetry (PIV), and have shown the flow to be complex and three-dimensional [3,4]. Stereoscopic PIV (SPIV) can obtain all three velocity components on a flow plane, and hence has the potential to provide better understanding of three dimensional flow characteristics. The objective of the current study was to use SPIV to measure steady flow, including turbulence properties, downstream of a BiMHV in a modeled aorta. The resulting dataset will be useful for CFD model validation, and the intent is to make it publicly available.

Finite Element Analysis of a Mechanical Heart Valve in Assembly

2012 ◽  
Vol 569 ◽  
pp. 487-490
Author(s):  
Liang Liang Wu ◽  
Guo Jiang Wan ◽  
Feng Zhou ◽  
Jie Yang ◽  
Nan Huang
Keyword(s):  
Heart Valve ◽  
Heart Valves ◽  
Mechanical Heart Valve ◽  
Mechanical Valve ◽  
Mechanical Method ◽  
Assembly Quality ◽  
Element Analysis ◽  
Bileaflet Mechanical Heart Valve ◽  
Valve Assembly ◽  
Ansys Workbench

The Bileaflet Mechanical Heart Valve (BMHV) has been the most successful replacement mechanical heart valve, and is currently the most commonly implanted mechanical valve. Although the BMHV is an improvement over previous mechanical heart valves, there are still serious associated complications with its use that must be eliminated. After the completion of the processing and surface modification, heart valve ring and heart valve leaflets constitute a single whole with mechanical method to achieve its function process. In order to ensure that the heart valve is stable and reliable in service, it is particularly important to improve the assembly quality. The theoretical analysis and simulation used of ANSYS Workbench software for the behavior of the heart valve assembly have been done, the experimental results were verified by testing apparatus, which is a helpful tool used to simulate the new structure of the heart valve assembly, and play a certain significance to improve the accuracy of the assembly.

An Initial Parametric Study on Fluid Flow Through Bileaflet Mechanical Heart Valves Using Computational Fluid Dynamics

1994 ◽  
Vol 208 (2) ◽  
pp. 63-72 ◽  
Author(s):  
M J King ◽  
T David ◽  
J Fisher
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Heart Valve ◽  
Heart Valves ◽  
Mechanical Heart Valve ◽  
Volumetric Flow Rate ◽  
Flow Fields ◽  
Opening Angle ◽  
Bileaflet Mechanical Heart Valve ◽  
Flow Through

The effect of leaflet opening angle on flow through a bileaflet mechanical heart valve has been investigated using computational fluid dynamics (CFD). Steady state, laminar flow for a Newtonian fluid at a Reynolds number of 1500 was used in the two-dimensional model of the valve, ventricle, sinus and aorta. This computational model was verified using one-dimensional laser Doppler velocimetry (LDV). Although marked differences in the flow fields and energy dissipation of the jets downstream of the valve were found between the CFD predictions and the three-dimensional experimental model, both methods showed similar trends in the changes of the flow fields as the leaflet opening angle was altered. As the opening angle increased the area of recirculating fluid downstream of the leaflets, the pressure drop across the valve and the volumetric flow rate through the outer orifice decreased. For opening angles greater than 80° the jet through the outer orifice recombined with the central jet downstream of the leaflet; for an opening angle of 78° the jet through the outer orifice impinged on the aortic wall before recombining with the central jet. This study suggests that the opening angle has a marked effect on the flow downstream of the bileaflet mechanical heart valve and that valves with opening angles greater than 80° are preferable.

scholarly journals Statistical Characteristics of Flow Field through Open and Semi-Closed Bileaflet Mechanical Heart Valve

2020 ◽  
Vol 2 (4) ◽  
pp. 184-196
Author(s):  
Oleksandr Voskoboinyk ◽  
Lidiia Tereshchenko ◽  
Vladimir Voskoboinick ◽  
Gabriela Fernandez ◽  
Andrey Voskoboinick ◽  
...  
Keyword(s):  
Heart Valve ◽  
Heart Valves ◽  
Mechanical Heart Valve ◽  
Pressure Sensors ◽  
Jet Flow ◽  
Operating Conditions ◽  
Mechanical Heart Valves ◽  
Statistical Characteristics ◽  
Diagnostic Tools ◽  
Bileaflet Mechanical Heart Valve

The formation of thrombi on the streamlined surface of the bileaflet mechanical heart valves is one of the main disadvantages of such valves. Thrombi block the valve leaflets and disrupt the cardiovascular system. Diagnosis of thrombosis of the bileaflet mechanical heart valves is relevant and requires the creation of effective diagnostic tools. Hydroacoustic registration of the heart noise is one of the methods for diagnosing the operation of a mechanical heart valve. The purpose of the research is to determine the statistical characteristics of the vortex and jet flow through the open and semi-closed bileaflet mechanical heart valve, to identify hydroacoustic differences and diagnostic signs to determine the operating conditions of the valve. Experimental studies were conducted in laboratory conditions on a model of the left atrium and left ventricle of the heart between which there was the bileaflet mechanical heart valve. Hydrodynamic noise was recorded by miniature pressure sensors, which were located downstream of the valve. The vortex and jet flow behind the prosthetic heart valve were non-linear, random processes and were analyzed using the methods of mathematical statistics and probability theory. The integral and spectral characteristics of the pressure field were obtained and the differences in the noise levels and their spectral components near the central and side jets for the open and semi-closed mitral valve were established. It was shown that hydroacoustic measurements could be an effective basis for developing diagnostic equipment for monitoring the bileaflet mechanical heart valve operation. Doi: 10.28991/SciMedJ-2020-0204-1 Full Text: PDF

Effect of Blood Pressure on Closing Dynamics of Bileaflet Mechanical Heart Valves

2012 ◽  
Author(s):  
Marcio H. Forleo ◽  
Brennan M. Johnson ◽  
Lakshmi P. Dasi
Keyword(s):  
Blood Pressure ◽  
Heart Valve ◽  
Heart Valves ◽  
Mechanical Heart Valve ◽  
Mechanical Heart Valves ◽  
Thromboembolic Complications ◽  
Stress Gradients ◽  
Bileaflet Mechanical Heart Valve ◽  
Sharp Stress ◽  
Rigid Design

Implantation of a bileaflet mechanical heart valve (BMHV) continues to be associated with a risk of thromboembolic complications despite anti-coagulation therapy1. This has been attributed to the structurally rigid design of the leaflets and valve mechanics combined with an intricate hinge mechanism for the rigid leaflets. The lack of a built in compliance within the valve mechanics presumably leads to sharp stress gradients within the flow as well as a violent closure of the valve often associated with the audible impact of the leaflets to the housing, and a potential for momentary cavitation of blood in the wake of leaflet impact.

Passive flow control of bileaflet mechanical heart valve leakage flow

2008 ◽  
Vol 41 (6) ◽  
pp. 1166-1173 ◽  
Author(s):  
Lakshmi P. Dasi ◽  
David W. Murphy ◽  
Ari Glezer ◽  
Ajit P. Yoganathan
Keyword(s):  
Flow Control ◽  
Heart Valve ◽  
Mechanical Heart Valve ◽  
Leakage Flow ◽  
Passive Flow Control ◽  
Bileaflet Mechanical Heart Valve ◽  
Passive Flow ◽  
Valve Leakage

scholarly journals Near Valve Flows and Potential Blood Damage During Closure of a Bileaflet Mechanical Heart Valve

2011 ◽  
Vol 133 (9) ◽  
Author(s):  
L. H. Herbertson ◽  
S. Deutsch ◽  
K. B. Manning
Keyword(s):  
Heart Valve ◽  
Heart Valves ◽  
Mechanical Heart Valve ◽  
In Vitro Study ◽  
Blood Damage ◽  
Bileaflet Mechanical Heart Valve ◽  
Fluid Velocities ◽  
Design Characteristics ◽  
Valve Housing

Blood damage and thrombosis are major complications that are commonly seen in patients with implanted mechanical heart valves. For this in vitro study, we isolated the closing phase of a bileaflet mechanical heart valve to study near valve fluid velocities and stresses. By manipulating the valve housing, we gained optical access to a previously inaccessible region of the flow. Laser Doppler velocimetry and particle image velocimetry were used to characterize the flow regime and help to identify the key design characteristics responsible for high shear and rotational flow. Impact of the closing mechanical leaflet with its rigid housing produced the highest fluid stresses observed during the cardiac cycle. Mean velocities as high as 2.4 m/s were observed at the initial valve impact. The velocities measured at the leaflet tip resulted in sustained shear rates in the range of 1500–3500 s−1, with peak values on the order of 11,000–23,000 s−1. Using velocity maps, we identified regurgitation zones near the valve tip and through the central orifice of the valve. Entrained flow from the transvalvular jets and flow shed off the leaflet tip during closure combined to generate a dominant vortex posterior to both leaflets after each valve closing cycle. The strength of the peripheral vortex peaked within 2 ms of the initial impact of the leaflet with the housing and rapidly dissipated thereafter, whereas the vortex near the central orifice continued to grow during the rebound phase of the valve. Rebound of the leaflets played a secondary role in sustaining closure-induced vortices.

Simulations of the Hinge Flow Fields of a Bileaflet Mechanical Heart Valve Under Physiologic Pulsatile Aortic Conditions

2008 ◽  
Author(s):  
Hélène A. Simon ◽  
Liang Ge ◽  
Iman Borazjani ◽  
Fotis Sotiropoulos ◽  
Ajit P. Yoganathan
Keyword(s):  
Heart Valve ◽  
Heart Valves ◽  
Mechanical Heart Valve ◽  
Prosthetic Heart Valve ◽  
Prosthetic Heart Valves ◽  
Valve Design ◽  
Bileaflet Mechanical Heart Valve ◽  
Hinge Flow ◽  
Blood Elements

Native heart valves with limited functionality are commonly replaced by prosthetic heart valves. Since the first heart valve replacement in 1960, more than three million valves have been implanted worldwide. The most widely implanted prosthetic heart valve design is currently the bileaflet mechanical heart valve (BMHV), with more than 130,000 implants every year worldwide. However, studies have shown that this valve design can still cause major complications, including hemolysis, platelet activation, and thromboembolic events. Clinical reports and recent in vitro experiments suggest that these thrombogenic complications are associated with the hemodynamic stresses imposed on blood elements by the complex non-physiologic flow induced by the valve, in particular in the hinge region.

Smoothed Particle Hydrodynamics Simulation of Flow Through a Bileaflet Mechanical Heart Valve: Advantages and Prospects

2011 ◽  
Author(s):  
Shahrokh Shahriari ◽  
Hoda Maleki ◽  
Ibrahim Hassan ◽  
Lyes Kadem
Keyword(s):  
Heart Valve ◽  
Smoothed Particle Hydrodynamics ◽  
Heart Valves ◽  
Mechanical Heart Valve ◽  
Particle Method ◽  
Generation Process ◽  
Bileaflet Mechanical Heart Valve ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Flow Through

A numerical simulation of pulsatile flow through a bileaflet mechanical heart valve is presented using smoothed particle hydrodynamics (SPH), a meshfree particle method. In SPH, the flow is modeled using fluid particles moving within the domain in which there is no mesh generation process and the conservation of mass is satisfied automatically. SPH showed a good capability to capture the main hemodynamic trend. The particle based nature of SPH allows also blood particle tracking, an important component in order to analysis the level of hemolysis induced by bileaflet mechanical heart valves.

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