A computational simulation of the effect of hybrid treatment for thoracoabdominal aortic aneurysm on the hemodynamics of abdominal aorta

Abstract

Hybrid visceral-renal debranching procedures with endovascular repair have been proposed as an appealing technique to treat conventional thoracoabdominal aortic aneurysm (TAAA). This approach, however, still remained controversial because of the non-physiological blood flow direction of its retrograde visceral revascularization (RVR) which is generally constructed from the aortic bifurcation or common iliac artery. The current study carried out the numerical simulation to investigate the effect of RVR on the hemodynamics of abdominal aorta. The results indicated that the inflow sites for the RVR have great impact on the hemodynamic performance. When RVR was from the distal aorta, the perfusion to visceral organs were adequate but the flow flux to the iliac artery significantly decreased and a complex disturbed flow field developed at the distal aorta, which endangered the aorta at high risk of aneurysm development. When RVR was from the right iliac artery, the abdominal aorta was not troubled with low WSS or disturbed flow, but the inadequate perfusion to the visceral organs reached up to 40% and low WSS and flow velocity predominated appeared at the right iliac artery and the grafts, which may result in the stenosis in grafts and aneurysm growth on the host iliac artery.

Functional Evaluation of Embedded Modular Single-Branched Stent Graft: Application to Type B Aortic Dissection With Aberrant Right Subclavian Artery

“…Image-based CFD simulation has been widely accepted as an alternative approach to study the hemodynamic properties, due to the difficulty of studying the outcome directly in vivo . Hemodynamic indicators could help to evaluate the efficacy of treatment options, such as the Norwood procedure ( 34 , 35 ), thoracic endovascular aortic repair and hybrid treatment procedure ( 13 , 15 ). However, hemodynamic simulation might be limited for that focuses on the vessel wall motion or that aims to investigate the mechanical interaction between vessel wall and the stent grafts due to the simplification of rigid wall in hemodynamic analysis.…”

Precise plan of hybrid treatment for thoracoabdominal aortic aneurysm: Hemodynamics of retrograde reconstruction visceral arteries from the iliac artery

“…So we first calculated the corresponding pressure drop from the supraceliac artery to each visceral organ in terms of the flowrate ratio for a healthy AA model, then we applied the same perfusion pressure to the corresponding visceral organ for the RVRs. In another words, assuming that the pressure at the supraceliac artery was 100 mmHg, the outlet pressure at each visceral artery was then defined taking into account the corresponding pressure drop for a healthy AA model[ 12 ]. The iliac outlet pressure was selected so that the entire flow rate was the same as that for the healthy one.…”

“…However, CIAs are indicated to provide the unique inflow of RVR because of the whole infrarenal aortic artery lesion with Crawford II/III/IV TAAA[ 10 , 11 ]. Our last paper revealed that an non-physiological hemodynamics of RVR from the infrarenal abdominal aortic or CIA will induce some potential risks to the host artery and the visceral organs[ 12 ]. However, the hemodynamic effects of RVR for Crawford type II/III/IV TAAA is still unknown.…”

“…Accordingly, this manuscript focuses on the hemodynamic influence of RVR on the aorta with Crawford II/III/IV TAAA using the CFD method described in our last paper[ 12 ]. This work and our last paper are mutually complementary and combine to reveal the hemodynamics of RVR with hybrid treatment for all types of TAAA, In addition, this study also aims to make a comparison between the employment of two bi-furcated grafts and one quar-furcated graft for RVR in terms of their hemodynamic performances so as to assess the ongoing performance of the visceral grafts and anastomotic sites.…”

Commentary: Physician-Modified Fenestrated/Branched EVAR and Hybrid Techniques for Acute Thoracoabdominal Aortic Pathologies: Inequality When Comparing Alternative Options With Different Philosophies Does Not Equal Lower Quality

“…1 In most reports in the literature, the retrograde approach has been used, with distal aortic or iliac artery inflow. According to a computational study by Wen et al, 28 retrograde visceral revascularization (RVR) from the distal aorta may reduce flow in the iliac artery and predispose the distal aorta to aneurysm formation. On the contrary, RVR from the iliac artery did not alter the flow in the limbs but reduced the flow in the visceral vessels and changed the flow in the iliac artery, predisposing to stenosis of the bypass grafts.…”