Date(s) - 06/24/2014
The chimney technique to extend landing zones for endovascular aortic repair (ChEVAR) has been increasingly used to treat the branched portions of the aorta. Although successful in the short-tem, long-term durability has been questioned due to concerns about device interactions and interferences in branch vessel anatomy implicit to ChEVAR. This study was performed to determine local hemodynamic changes that result from ChEVAR.
Patients undergoing ChEVAR were evaluated with CT imaging pre and post-operatively, and images were used to reconstruct the vessel 3D-geometry. Computational fluid dynamic (CFD) simulations were used to evaluate changes in cross-sectional areas, pressure, and wall shear stress in the superior mesenteric (SMA) and renal arteries.
Due to the inherent configuration of each visceral artery, it was found that ChEVAR had varying effects on the 3D conformation of the vessels, and consequently on the hemodynamics. In the SMA, which has a natural caudal orientation, the conformational change was modest, and there were minimal changes in the local flow dynamics. However, dramatic changes in the 3D configuration of the naturally perpendicular renal arteries were observed, with the stents forcing the vessels into a caudal orientation. These changes resulted in significant perturbations in flow dynamics, with up to a 300% elevation increase in both the local wall shear stress and pressure gradient.
The placement of intravascular stents in aortic branch vessels often leads to an unavoidable change in vessel conformation, causing significant modifications in the local flow patterns. In particular, the perpendicular orientation of the renal arteries was forced into a caudal angle by the stents inducing dramatic hemodynamic changes. The natural caudal orientation of the SMA was minimally affected, and demonstrated fewer alterations in these flow patterns.
The objective of this project is to investigate the relationship between anatomic and hemodynamic changes and compromised distal perfusion and/or stent thrombosis formation.