Computational Fluid Dynamics Analysis of the Effect of a New Dissection Specific Stent Graft on Preventing Distal Stent Graft Induced New Entry (dSINE) in Patients With Chronic Type B Aortic Dissection

Abstract

Objective: Distal stent graft induced new entry (dSINE) is being increasingly reported after TEVAR for chronic type B aortic dissection (cTBAD). In addition to aortic wall fragility, stent graft oversizing due to the discrepancy between the sizes of proximal and distal landing zones and the less compliant dissection flap to the expansion of the stent graft carry a higher risk of a new intimal tear. To address these risk factors, a dissection specific stent graft (DSSG) was designed to include features such as: no proximal barbs, a customised longer body length with substantial taper, reduced radial force in the second and third distal stents that are sited internally to avoid any contact with the dissection membrane, and removal of the final stent, leaving 30 mm of unsupported Dacron fabric (“endovascular elephant trunk”) (Fig. 1). The combination of patient specific anatomy and the implanted endograft brings about changes in haemodynamic of the stented and non-stented regions that can have consequences on flow patterns and shear stress distributions. As such, wall shear stress (WSS) is of particular interest, and computational fluid dynamics (CFD) can provide information on WSS. As a continuation of previous work reporting midterm clinical effectiveness of DSSG with low rates of dSINE,1 the present study focuses on identifying haemodynamic properties (WSS) of DSSG compared with those of standard thoracic stent graft (STSG) by means of CFD simulations.