Hemodynamics of Aortas with Multiple Overlapping Endografts: A New Design Consideration

Abstract

Endovascular Aneurysm Repair (EVAR), a method for repairing Abdominal Aortic Aneurysm (AAA), has increasingly been performed on patients with suitable anatomy, and has generated a great deal of interest toward enhancing minimallyinvasive therapeutics. However, there exist clinical cases of patients with large affected zones where one single oversized endograft does not provide a proper solution, often due to highly curved and irregular geometries. Therefore, the clinical practice of endograft implantation in patients with extended regions of arterial damage constitutes the use of multiple standard-sized endografts, usually overlapping to ensure a full coverage of the diseased areas. While being a clinically appealing practice, there exist reports on the confounding effects of using multiple, overlapping stents and the increased risk of adverse clinical outcome. The impacts of using multiple, overlapping stents on hemodynamics visa- vis cardiovascular mechanics have not been fully examined, and we speculate that resulting local flow complications contribute to the escalation of such cases. In this article, we review the arterial hemodynamic parameters in physiological conditions, as well as under employment of single and multiple stents, and highlight the major concerning impacts on the quantified flow parameters. Even though stent overlap cannot always be avoided in clinical practice, an improved stent design and overlapping deployment strategies could potentially minimize flow complications and compounding pathological effects.