scholarly journals The Effect of Implantation Orientation of a Bileaflet Mechanical Heart Valve on Kinematics and Hemodynamics in an Anatomic Aorta

2010 ◽  
Vol 132 (11) ◽  
Author(s):  
Iman Borazjani ◽  
Fotis Sotiropoulos
Keyword(s):  
Heart Valve ◽  
Mechanical Heart Valve ◽  
Three Dimensional ◽  
Symmetry Plane ◽  
Convergence Acceleration ◽  
Immersed Boundary ◽  
Strongly Coupled ◽  
Bileaflet Mechanical Heart Valve ◽  
Acceleration Technique ◽  
Magnetic Resonance Imaging Mri

We carry out three-dimensional high-resolution numerical simulations of a bileaflet mechanical heart valve under physiologic pulsatile flow conditions implanted at different orientations in an anatomic aorta obtained from magnetic resonance imaging (MRI) of a volunteer. We use the extensively validated for heart valve flow curvilinear-immersed boundary (CURVIB) fluid-structure interaction (FSI) solver in which the empty aorta is discretized with a curvilinear, aorta-conforming grid while the valve is handled as an immersed boundary. The motion of the valve leaflets are calculated through a strongly coupled FSI algorithm implemented in conjunction with the Aitken convergence acceleration technique. We perform simulations for three valve orientations, which differ from each other by 45 deg and compare the results in terms of leaflet motion and flow field. We show that the valve implanted symmetrically relative to the symmetry plane of the ascending aorta curvature exhibits the smallest overall asymmetry in the motion of its two leaflets and lowest rebound during closure. Consequently, we hypothesize that this orientation is beneficial to reduce the chance of intermittent regurgitation. Furthermore, we find that the valve orientation does not significantly affect the shear stress distribution in the aortic lumen, which is in agreement with previous studies.

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.

scholarly journals Erratum to: Simulation of the Three-Dimensional Hinge Flow Fields of a Bileaflet Mechanical Heart Valve Under Aortic Conditions

2010 ◽  
Vol 38 (3) ◽  
pp. 1257-1257 ◽  
Author(s):  
Hélène A. Simon ◽  
Liang Ge ◽  
Iman Borazjani ◽  
Fotis Sotiropoulos ◽  
Ajit P. Yoganathan
Keyword(s):  
Heart Valve ◽  
Mechanical Heart Valve ◽  
Three Dimensional ◽  
Flow Fields ◽  
Bileaflet Mechanical Heart Valve ◽  
Hinge Flow

Direct numerical simulation of the pulsatile flow through an aortic bileaflet mechanical heart valve

2009 ◽  
Vol 622 ◽  
pp. 259-290 ◽  
Author(s):  
M. D. DE TULLIO ◽  
A. CRISTALLO ◽  
E. BALARAS ◽  
R. VERZICCO
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Heart Valve ◽  
Pulsatile Flow ◽  
Damage Index ◽  
Mechanical Heart Valve ◽  
Immersed Boundary ◽  
Reynolds Stresses ◽  
Bileaflet Mechanical Heart Valve ◽  
Flow Through

This work focuses on the direct numerical simulation of the pulsatile flow through a bileaflet mechanical heart valve under physiological conditions and in a realistic aortic root geometry. The motion of the valve leaflets has been computed from the forces exerted by the fluid on the structure both being considered as a single dynamical system. To this purpose the immersed boundary method, combined with a fluid–structure interaction algorithm, has shown to be an inexpensive and accurate technique for such complex flows. Several complete flow cycles have been simulated in order to collect enough phase-averaged statistics, and the results are in good agreement with experimental data obtained for a similar configuration. The flow analysis, strongly relying on the data accessibility provided by the numerical simulation, shows how some features of the leaflets motion depend on the flow dynamics and that the criteria for the red cell damages caused by the valve need to be formulated using very detailed analysis. In particular, it is shown that the standard Eulerian computation of the Reynolds stresses, usually employed to assess the risk of haemolysis, might not be adequate on several counts: (i) Reynolds stresses are only one part of the solicitation, the other part being the viscous stresses, (ii) the characteristic scales of the two solicitations are very different and the Reynolds stresses act on lengths much larger than the red cells diameter and (iii) the Eulerian zonal assessment of the stresses completely misses the information of time exposure to the solicitation which is a fundamental ingredient for the phenomenon of haemolysis. Accordingly, the trajectories of several fluid particles have been tracked in a Lagrangian way and the pointwise instantaneous viscous stress tensor has been computed along the paths. The tensor has been then reduced to an equivalent scalar using the von Mises criterion, and the blood damage index has been evaluated following Grigioni et al. (Biomech. Model Mechanobiol., vol. 4, 2005, p. 249).

Three Dimensional Fluid Mechanics of the Sinus of Valsalva With a Bileaflet Mechanical Heart Valve

2007 ◽  
Author(s):  
Takanobu Yagi ◽  
Daisuke Ishikawa ◽  
Hiroyuki Sudo ◽  
Shotaro Wakasa ◽  
William Yang ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Fluid Mechanics ◽  
Heart Valve ◽  
Mechanical Heart Valve ◽  
Three Dimensional ◽  
Diagnostic Tools ◽  
Sinus Of Valsalva ◽  
Bileaflet Mechanical Heart Valve ◽  
Valve Closing Dynamics

Fluid mechanics of the sinus of Valsalva is an underlying basis of aortic surgery. Bellhouse and Talbot first reported the closure mechanism of the human aortic valve in vitro, and found that a vortex motion in the sinus facilitates the initial closing response, thus minimizing the regurgitation [1]. Since their early study, a variety of researches have been conducted to gain systematic understanding of the flow in the sinus of Valsalva. Phase-contrast MRI technique in vivo and computational fluid dynamics in vitro are modern flow diagnostic tools, both of which potentially has a capability of characterizing the three-dimensional flow. However, the flow in reality is strongly affected by the opening and closing dynamics of the aortic valve, and vice versa. This fluid-structure coupling has yet to be understood systematically. This study aims to clarify the mechanism of the coupling in vitro with a bileaflet mechanical heart valve by means of 2D PIV and 3D Stereo PIV technique [2]. An emphasis is placed on the geometrical effect of the sinus of Valsalva, where three geometries, namely the Anatomical, Neosinus and Straight models, are compared on the flow dynamics and valve closing dynamics.

Sign in / Sign up

Export Citation Format

Share Document