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Research Papers

Hemodynamics of an End-to-Side Anastomotic Graft for a Pulsatile Pediatric Ventricular Assist Device

[+] Author and Article Information
Ning Yang

Department of Bioengineering, Pennsylvania State University, University Park, PA 16802

Steven Deutsch

Department of Bioengineering, Pennsylvania State University, University Park, PA 16802; Applied Research Laboratory, Pennsylvania State University, University Park, PA 16802

Eric G. Paterson

Applied Research Laboratory, Pennsylvania State University, University Park, PA 16802; Department of Mechanical Engineering, Pennsylvania State University, University Park, PA 16802

Keefe B. Manning1

Department of Bioengineering, Pennsylvania State University, University Park, PA 16802kbm10@psu.edu

1

Corresponding author.

J Biomech Eng 132(3), 031009 (Feb 17, 2010) (13 pages) doi:10.1115/1.4000872 History: Received April 13, 2009; Revised October 20, 2009; Posted December 22, 2009; Published February 17, 2010; Online February 17, 2010

Numerical simulations are performed to investigate the flow within the end-to-side proximal anastomosis of a pulsatile pediatric ventricular assist device (PVAD) to an aorta. The anastomotic model is constructed from a patient-specific pediatric aorta. The three great vessels originating from the aortic arch— brachiocephalic (innominate), left common carotid, and left subclavian arteries—are included. An implicit large eddy simulation method based on a finite volume approach is used to study the resulting turbulent flow. A resistance boundary condition is applied at each branch outlet to study flow splitting. The PVAD anastomosis is found to alter the aortic flow dramatically. More flow is diverted into the great vessels with the PVAD support. Turbulence is found in the jet impingement area at peak systole for 100% bypass, and a maximum principal normal Reynolds stress of 7081dyn/cm2 is estimated based on ten flow cycles. This may be high enough to cause hemolysis and platelet activation. Regions prone to intimal hyperplasia are identified by combining the time-averaged wall shear stress and oscillatory shear index. These regions are found to vary, depending on the percentage of the flow bypass.

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Figures

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Figure 1

Computational geometries: (a) healthy patient-specific pediatric aortic model (NIH-Georgia Tech Fontan Anatomy Database ID: CHOP007); (b) proximal anastomotic model; (c) enlarged distal view of the graft junction indicated by the black square in (b)

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Figure 2

Flow solver validation: (a) pipe inlet pressure and flow waveforms; (b) comparison of the analytical and numerical solutions in terms of the velocity composite Fourier coefficients. Note that the experimental and composite pressure waveforms completely overlap with one another.

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Figure 3

Grid study on the healthy pediatric aortic model: (a) effect of grid on the pressure and flow waveforms at each boundary; (b) effect of grid on WSS in six locations. Note that the results of the grid study overlap in Fig. 1

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Figure 7

Velocity magnitude contour (unit: m/s) for 100% bypass: (a) at peak systole; (b) at mid-deceleration; and (c) at early diastole

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Figure 8

Magnitude contour of Reynolds stress (unit: dyn/cm2) at peak systole for 100% bypass: (a) maximum principal normal stress; (b) maximum shear stress

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Figure 9

WSS magnitude (unit: dyn/cm2) contour at peak systole: (a) healthy pediatric aorta; (b) 50% bypass; and (c) 100% bypass

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Figure 10

Pressure contour (unit: mm Hg) at peak systole for 100% bypass

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Figure 11

Contour of time-averaged WSS (unit: dyn/cm2): (a) healthy pediatric aorta; (b) 50% bypass; and (c) 100% bypass

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Figure 12

Contour of the OSI: (a) healthy pediatric aorta; (b) 50% bypass; and (c) 100% bypass

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Figure 13

Regions prone to the development of IH (in dark): (a) healthy pediatric aorta; (b) 50% bypass; and (c) 100% bypass

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Figure 6

Velocity magnitude contour (unit: m/s) for 50% bypass: (a) at peak systole; (b) at mid-deceleration; and (c) at early diastole

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Figure 5

Velocity magnitude contour (unit: m/s) for the healthy pediatric aorta: (a) at peak systole; (b) at mid-deceleration; and (c) at early diastole

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Figure 4

Pressure and flow waveforms at each boundary for 50% bypass and 100% bypass. Note that the different bypass results are differentiated by line thickness.

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