Effects of major endoleaks on a stented abdominal aortic aneurysm.
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.
Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695-7910, USA.
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D001012:Aorta, Abdominal / Q000503:physiopathology / Q000601:surgery; D017544:Aortic Aneurysm, Abdominal / Q000150:complications / Q000503:physiopathology* / Q000601:surgery*; D001783:Blood Flow Velocity; D016063:Blood Loss, Surgical / Q000517:prevention & control; D001794:Blood Pressure; D001807:Blood Vessel Prosthesis / Q000009:adverse effects*; D003198:Computer Simulation; D006801:Humans; D008955:Models, Cardiovascular; D019106:Postoperative Hemorrhage / Q000209:etiology / Q000503:physiopathology*; D033081:Shear Strength; D015607:Stents / Q000009:adverse effects*; D013314:Stress, Mechanical; D016896:Treatment Outcome