A Novel Attempt to Standardize Results of CFD Simulations Basing on Spatial Configuration of Aortic Stent-Grafts.

Currently, studies connected with Computational Fluid Dynamic (CFD) techniques focus on assessing hemodynamic of blood flow in vessels in different conditions e.g. after stent-graft's placement. The paper propose a novel method of standardization of results obtained from calculations of stent-grafts' "pushing forces" (cumulative WSS--Wall Shear Stress), and describes its usefulness in diagnostic process. AngioCT data from 27 patients were used to reconstruct 3D geometries of stent-grafts which next were used to create respective reference cylinders. We made an assumption that both the side surface and the height of a stent-graft and a reference cylinder were equal. The proposed algorithm in conjunction with a stent-graft "pushing forces" on an implant wall, allowed us to determine which spatial configuration of a stent-graft predispose to the higher risk of its migration. For stent-grafts close to cylindrical shape (shape factor φ close to 1) WSS value was about 267 Pa, while for stent-grafts different from cylindrical shape (φ close to 2) WSS value was about 635 Pa. It was also noticed that deformation in the stent-graft's bifurcation part impaired blood flow hemodynamic. Concluding the proposed algorithm of standardization proved its usefulness in estimating the WSS values that may be useful in diagnostic process. Angular bends or tortuosity in bifurcations of an aortic implant should be considered in further studies of estimation of the risk of implantation failure

The shape factors and WSS values for the analyzed stent-grafts.

<p>The shape factors and WSS values for the analyzed stent-grafts.</p

The WSS values in a function of shape factor <i>φ</i> for analyzed stent-grafts.

<p>Correlation was calculated with Spearman non-parametric test.</p

A scheme of reference cylinder for each stent-graft calculation procedure.

<p>A scheme of reference cylinder for each stent-graft calculation procedure.</p

Reference blood velocity profile from USG-Doppler used as a inlet boundary condition for analyzed stent-grafts.

<p>Reference blood velocity profile from USG-Doppler used as a inlet boundary condition for analyzed stent-grafts.</p

An example for reconstructed spatial configuration of analyzed stent-grafts.

<p>An example for reconstructed spatial configuration of analyzed stent-grafts.</p

Spatial configuration of stent-grafts that are not on the regression line.

<p>With red colour stent-grafts that are not on the regression line. With violet colour corresponding by shape factor, stent-grafts close to the regression line.</p

Geometrical parameters (angular bends and tortuosity) for the selected stent-grafts.

<p>A_L—angular bend in left branch of a stent-graft, A_R—angular bend in the right branch of a stent-graft, T_L—tortuosity of a left branch of a stent-graft, T_R—tortuosity of a right branch of a stent-graft.</p