Flow characteristics in a model of a left ventricle in the presence of a dysfunctional mitral mechanical heart valve

Artificial heart valves may dysfunction, leading to thrombus and/or pannus formations. Computational fluid dynamics is a promising tool for improved understanding of heart valve hemodynamics that quantify detailed flow velocities and turbulent stresses to complement Doppler measurements. This combined information can assist in choosing optimal prosthesis for individual patients, aiding in the development of improved valve designs, and illuminating subtle changes to help guide more timely early intervention of valve dysfunction. In this computational study, flow characteristics around a bileaflet mechanical heart valve were investigated. The study focused on the hemodynamic effects of leaflet immobility, specifically, where one leaflet does not fully open. Results showed that leaflet immobility increased the principal turbulent stresses (up to 400%), and increased forces and moments on both leaflets (up to 600% and 4000%, respectively). These unfavorable conditions elevate the risk of blood cell damage and platelet activation, which are known to cascade to more severe leaflet dysfunction. Leaflet immobility appeared to cause maximal velocity within the lateral orifices. This points to the possible importance of measuring maximal velocity at the lateral orifices by Doppler ultrasound (in addition to the central orifice, which is current practice) to determine accurate pressure gradients as markers of valve dysfunction.

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Stereoscopic PIV of Steady Flow Through a Bileaflet Mechanical Heart Valve

ASME 2008 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2008-192962 ◽

2008 ◽

Cited By ~ 1

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.

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Characterization of Hemodynamic Performance and Degree of Flow Redirection in the Left Ventricle Dependent on the Mitral Mechanical Heart Valve Orientation

Advances in Bioengineering ◽

10.1115/imece2002-32570 ◽

2002 ◽

Author(s):

Olga Pierrakos ◽

Pavlos P. Vlachos ◽

Demetri P. Telionis ◽

Saami Yazdani ◽

Ali Etebari

Keyword(s):

Left Ventricle ◽

Heart Valve ◽

Mechanical Heart Valve ◽

Efficient Operation ◽

Flow Disturbances ◽

Energy Conserving ◽

Flow Through ◽

Healthy Functioning ◽

Hemodynamic Performance

Recent groundbreaking work by Kilner et al. [1] demonstrated that a healthy functioning heart redirects the flow through the left ventricle (LV) in an asymmetric manner, which results in an energy conserving mechanism. Heart valve replacement alters the physiological operation of the heart significantly affecting its hemodynamic performance. As a result, orientation and valve design could play a significant role in the energy efficient operation of the heart; therefore, orienting MHVs so that flow disturbances are minimized enhances the hemodynamic performance of the LV.

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Multiphysics and Multiscale Simulation: Application to a Coupled Model of the Left Ventricle and a Mechanical Heart Valve

International Journal for Multiscale Computational Engineering ◽

10.1615/intjmultcompeng.v6.i1.60 ◽

2008 ◽

Vol 6 (1) ◽

pp. 65-76 ◽

Cited By ~ 5

Author(s):

V. Diaz-Zuccarini ◽

D. R. Hose ◽

P. V. Lawford ◽

A. J. Narracott ◽

D. Rafiroiu

Keyword(s):

Left Ventricle ◽

Heart Valve ◽

Mechanical Heart Valve ◽

Coupled Model ◽

Multiscale Simulation

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Experimental and Computational Studies of the Aortic Bi-leaflet Mechanical Heart Valve (BMHV) Hemodynamics in an Idealized Left Ventricle

QScience Proceedings ◽

10.5339/qproc.2012.heartvalve.4.64 ◽

2012 ◽

Vol 2012 (4) ◽

pp. 64

Author(s):

Trung Bao Le ◽

Brandon Chaffin ◽

Lucia Mirabella ◽

Arvind Santhanakrishnan ◽

Ajit Yoganathan ◽

...

Keyword(s):

Left Ventricle ◽

Heart Valve ◽

Mechanical Heart Valve ◽

Computational Studies

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

10.1615/tfec2018.bio.021666 ◽

2018 ◽

Cited By ~ 2

Author(s):

Fardin Khalili ◽

Peshala P. T Gamage ◽

Hansen A Mansy

Keyword(s):

Heart Valve ◽

Aortic Root ◽

Mechanical Heart Valve ◽

Flow Characteristics ◽

Bileaflet Mechanical Heart Valve

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Impact of Aortic Prosthetic Heart Valve Dysfunction on Left Ventricular Afterload and on the Accuracy of Echo-Doppler Measurements

ASME 2011 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2011-53769 ◽

2011 ◽

Author(s):

Othman Smadi ◽

Zahra Keshavarz-Motamed ◽

Ibrahim Hassan ◽

Philippe Pibarot ◽

Lyes Kadem

Keyword(s):

Left Ventricle ◽

Heart Valve ◽

Heart Valves ◽

Mechanical Heart Valve ◽

Prosthetic Heart Valve ◽

Left Ventricular ◽

Heart Valve Disease ◽

Thromboembolic Events ◽

Left Heart ◽

Ventricular Afterload

Left heart side (left ventricle and left atrium) is responsible for delivering the oxygenated blood to all body organs, where a relatively strong left ventricle contraction is needed to deliver around 5 liters of blood per minute. As a consequence, the left heart side experiences a high pressure (∼150 mmHg). Therefore, the dysfunction (stenosis or incompetence) in the aortic and/or mitral heart valves in the left side of the heart is more common than the dysfunction in the pulmonary and tricuspid heart valves in the right side of the heart (Yoganathan et al., 2004). Heart valve surgical replacement is the most effective solution in severe functional heart valve disease (Pibarot and Dumesnil, 2009). Almost, half of the total implants of prosthetic heart valves (∼300,000) are mechanical (mainly bileaflet). In case of mechanical heart valve (MHV), a lifelong anti-coagulant should be taken to avoid thromboembolic events. Despite the significant improvement in valve design resulting in minimizing prosthetic valve complications (thromboembolic events or pannus formation), these complications are still possible with MHV Implantation.

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A Comparison of a Moderate with Moderate-high Intensity Oral Anticoagulant Treatment in Patients with Mechanical Heart Valve Prostheses

Thrombosis and Haemostasis ◽

10.1055/s-0038-1656064 ◽

1997 ◽

Vol 77 (05) ◽

pp. 0839-0844 ◽

Cited By ~ 34

Author(s):

Vittorio Pengo ◽

Fabio Barbero ◽

Alberto Banzato ◽

Elisabetta Garelli ◽

Franco Noventa ◽

...

Keyword(s):

Heart Valve ◽

High Intensity ◽

Oral Anticoagulant ◽

Oral Anticoagulants ◽

Mechanical Heart Valve ◽

Moderate Intensity ◽

Minor Bleeding ◽

Anticoagulant Treatment ◽

Oral Anticoagulant Treatment ◽

Valve Prostheses

SummaryBackground. The long-term administration of oral anticoagulants to patients with mechanical heart valve prostheses is generally accepted. However, the appropriate intensity of oral anticoagulant treatment in these patients is still controversial.Methods and Results. From March 1991 to March 1994, patients referred to the Padova Thrombosis Center who had undergone mechanical heart valve substitution at least 6 months earlier were randomly assigned to receive oral anticoagulants at moderate intensity (target INR = 3) or moderate-high intensity (target INR = 4). Principal end points were major bleeding, thromboembolism and vascular death. Minor bleeding was a secondary end-point.A total of 104 patients were assigned to the target 3 group and 101 to the target 4 group; they were followed for from 1.5 years to up 4.5 years (mean, 3 years). Principal end-points occurred in 13 patients in the target 3 group (4 per 100 patient-years) and in 20 patients in the target 4 group (6.9 per 100 patient-years). Major hemorrhagic events occurred in 15 patients, 4 in the target 3 group (1.2 per 100 patient-years) and 11 in the target 4 group (3.8 per 100 patient-years) (p = 0.019). The 12 recorded episodes of thromboembolism, 4 of which consisted of a visual deficit, were all transient ischemic attacks, 6 in the target 3 group (1.8 per 100 patient-years) and 6 in the target 4 group (2.1 per 100 patient- years). There were 3 vascular deaths in each group (0.9 and 1 per 100 patient-years for target 3 and target 4 groups, respectively). Minor bleeding episodes occurred 85 times (26 per 100 patient-years) in the target 3 group and 123 times (43 per 100 patient-years) in the target 4 group (p = 0.001).Conclusions. Mechanical heart valve patients on anticoagulant treatment who had been operated on at least 6 months earlier experienced fewer bleeding complications when maintained on a moderate intensity regimen (target INR = 3) than those on a moderate-high intensity regimen (target INR = 4). The number of thromboembolic events and vascular deaths did not differ between the two groups.

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