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TECHNICAL PAPERS: Fluids/Heat/Transport

Effects of Major Endoleaks on a Stented Abdominal Aortic Aneurysm

[+] Author and Article Information
Z. Li

Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695-7910

C. Kleinstreuer1

Department of Mechanical and Aerospace Engineering and Department of Biomedical Engineering, North Carolina State University, Raleigh, NC 27695-7910ck@ncsu.edu

1

To whom correspondence should be addressed.

J Biomech Eng 128(1), 59-68 (Sep 02, 2005) (10 pages) doi:10.1115/1.2132376 History: Received April 22, 2005; Revised September 02, 2005

Insertion of a stent-graft into an aneurysm, especially abdominal aortic aneurysms (AAAs), is a very attractive surgical intervention; however, it is not without major postoperative complications, such as endoleaks. An endoleak is the transient accumulation of blood in the AAA cavity, which is formed by the stent-graft and AAA walls. Of the four blood pathways, a type I endoleak constitutes the major one. Thus, focusing on both proximal and distal type I endoleaks, i.e., the minute net influx of blood past the attachment points of a stent-graft into the AAA cavity, the transient three-dimensional interactions between luminal blood flow, stent-graft wall, leakage flow, and AAA wall are computationally simulated. For different type I endoleak scenarios and inlet pressure wave forms, the impact of type I endoleaks on cavity pressure, wall stress, and stent-graft migration force is analyzed. The results indicate that both proximal type I-a and distal type I-b endoleaks may cause cavity pressures close to a patient’s systemic pressure; however, with reduced pulsatility. As a result, the AAA-wall stress is elevated up to the level of a nonstented AAA and, hence, such endoleaks render the implant useless in protecting the AAA from possible rupture. Interestingly enough, the net downward force acting on the implant is significantly reduced; thus, in the presence of endoleaks, the risk of stent-graft migration may be mitigated.

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Copyright © 2006 by American Society of Mechanical Engineers
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Figures

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Figure 1

Schematics of stented AAA model and inlet/outlet profiles

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Figure 2

Influence of aperture size on time-varying leakage rate

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Figure 3

Effect of type I-a endoleak on stented AAA (only half part display from midplane, k=0.05; t∕T=0.27)

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Figure 4

AAA/EVG wall stress contour and lumen pressure distributions (t∕T=0.27)

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Figure 5

Effects of type I-a aperture size on stented AAA: (a) leakage rate, (b) sac pressure, (c) maximum AAA wall stress, and (d) EVG migration force

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Figure 6

Effects of hypertension on stented AAA with type I-a endoleak: (a) Different blood pressure wave forms, (b) leakage rate, (c) sac pressure, (d) maximum wall stress, and (e) migration force

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Figure 7

Effect of type I-b endoleak on stented AAA (midplane, t∕T=0.27)

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Figure 8

Pressure comparison between different type I endoleaks

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