Experimental Study of Collateral Patency following Overlapped Multilayer Flow Modulators Deployment

Abstract

Decades after its introduction, endovascular aneurysm repair remains a challenging procedure with risks of collateral patency failure. Here, we investigate the ability of a porous stent, the Multilayer Flow Modulator (MFM), to maintain renal perfusion after a single or overlapping case. Silicone models representing an ideal infrarenal AAA geometry were used to analyze and compare three cases (control, single MFM and two overlapped MFMs). Micro-computed tomography was used to image the deployed MFM devices geometry and evaluate pore size and density along with porosity in both two (planimetric) and three dimensions (gravimetric). Laser particle image velocimetry (PIV) experiments were performed to image velocity and vorticity fields at the aorta-renal bifurcation. Flow experiments revealed renal arteries perfusion preservation in both single and overlapped cases. Microstructure analysis revealed an uneven distribution of wires in the MFM devices leading to local change in planimetric porosity and pore size. Overlap of a second MFM device led to a significant decrease in those 2D metrics but did not affect the gravimetric porosity and the branch perfusion. This first microstructure evaluation of MFM device combined with flow experiments revealed the ability of the device to preserve collateral flow thanks to a highly porous microstructure.