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Research Papers

Simulation of Portal Hemodynamic Changes in a Donor After Right Hepatectomy

[+] Author and Article Information
Cheng-Maw Ho, Rey-Hen Hu

Department of Surgery, National Taiwan University Hospital, Taipei, 100 Taiwan, R.O.C.

Reui-Kuo Lin

Department of Engineering Science and Ocean Engineering, National Taiwan University, Taipei, 104 Taiwan, R.O.C.

Shun-Feng Tsai

Department of Marine Engineering, National Taiwan Ocean University, Keelung, 202 Taiwan, R.O.C.

Po-Chin Liang

Department of Medical Imaging, National Taiwan University Hospital, Taipei, 100 Taiwan, R.O.C.

Tony Wen-Hann Sheu1

Department of Engineering Science and Ocean Engineering, National Taiwan University, Taipei, 104 Taiwan, R.O.C.twhsheu@ntu.edu.tw

Po-Huang Lee1

Department of Surgery, National Taiwan University Hospital, Taipei, 100 Taiwan, R.O.C.pohuang1115@ntu.edu.tw

1

Corresponding authors.

J Biomech Eng 132(4), 041002 (Mar 08, 2010) (7 pages) doi:10.1115/1.4000957 History: Received April 22, 2009; Revised October 14, 2009; Posted January 06, 2010; Published March 08, 2010; Online March 08, 2010

Remnant livers will be regenerated in live donors after a large volume resection for transplantation. How the structures and hemodynamics of portal vein will evolve with liver regeneration remains unknown. This prompts the present hemodynamic simulation for a 25 year-old man who received a right donor lobectomy. According to the magnetic resonance imaging/computed tomography images taken prior to the operation and one month after the operation, three sequential models of portal veins (pre-op, immediately after the operation, and one-month post-op) were constructed by AMIRA ® and HYPERMESH ® , while the immediately after the operation model was generated by removing the right branch in the pre-op model. Hemodynamic equations were solved subject to the sonographically measured inlet velocity. The simulated branch velocities were compared with the measured ones. The predicted overall pressure in the portal vein after resection was found to increase to a magnitude that has not reached to an extent possibly leading to portal hypertension. As expected, blood pressure has a large change only in the vicinity of the resection region. The branches grew considerably different from the original one as the liver is regenerated. Results provide useful evidence to justify the current computer simulation.

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Copyright © 2010 by American Society of Mechanical Engineers
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Figures

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Figure 2

The portal vessels and liver, which were reconstructed from the medical images. (a) Vessels before the operation. The line “—” represents the resection line. (b) Regenerated vessels one month after the operation. (c) The visualized resection for a donor’s right lobectomy. (d) The remnant liver is regenerated one month after the operation. The vessels grew significantly different from the original vessels one month after the resection.

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Figure 4

Correlation of the Doppler measurement of portal vein velocity and the predicted velocity from the models. (a) Measured right portal vein velocities (point 1) before the operation versus the predicted results from the pre-operative model (red curve). The mean predicted velocity (green line). The averaged, measured velocity in the blue line for comparison. (b) Measured left portal vein velocities (point 2) before the operation versus the predicted results from the pre-operative model (red curve). The mean predicted velocity (green line). The averaged, measured velocity in the blue line for comparison. (c) Post-operative portal vein velocity measured one month later versus the predicted velocity at point 3 in the one-month post-operative model (red curve). The mean predicted velocity (green line). The averaged, measured velocity in the location near point 3 was 37.4 cm/s.

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Figure 6

The simulated pressure contours in the portal vein structures. (a) pre-operation, (b) immediately after the operation, and (c) one month after the operation. The increased pressure in the portal vein shaft (orange color) immediately after the operation was dropped to the pre-operative situation (green/yellow) one month later.

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Figure 7

The simulated shear stress contours in the portal vein structures. (a) pre-operation, (b) immediately after the operation, and (c) one month after the operation. The shear stress on the shaft one month after the operation is increased when comparing with that on the immediately after the operation model.

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Figure 1

Medical images versus real-life liver and portal vein. (a) A typical MRI angiography image of portal vein. (b) A cross-sectional view of the CT image. (c) Intraoperative view of the liver and the right branch of the portal vein (looped by a blue tape) before the liver resection. (d) The liver was split into the right half and the left half with the right portal vein connected in hand (▼). (e) The right lobe and right portal vein were removed and the cutting surface of the junction of the portal vein was sutured with stitches (→). Note also that the cutting surface of the left lobe liver was shown (A: anterior, C: cephalic, and R: right).

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Figure 3

The plot of three vessel models under current investigation and their detailed surface meshes. (a) before the operation, (b) immediately after the operation, and (c) one month after the operation.

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Figure 5

The simulated particle tracers in the portal vein structures. (a) pre-operation, (b) immediately after the operation, and (c) one month after the operation. The streamlines, laminar in pre-op status, became more complex even at a time of one month after the operation.

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