Hemodynamics in renal arteries with partial coverage after endovascular aneurysm repair affected by renal orientations

Endovascular aortic repair (EVAR) has been increasingly used to treat abdominal aortic aneurysm (AAA) due to its lower mortality and shorter recovery time. However, the complications caused by renal artery coverage remained a major concern. In this study, three types of renal orientation and five types of partial renal coverage degree were adopted to numerically investigate the flow pattern, wall shear stress distribution, and blood perfusion during a cardiac cycle. The results show that as for the mild partial coverage (=<30%), the renal artery with a downward orientation suffered fewer unfavorable wall shear stress (WSS) distribution and more blood perfusion. It should be noted that the renal artery with horizontal orientation suffered more unfavorable WSS distribution. In terms of severe coverage (≥50%), all of the renal arteries displayed highly disturbed wall shear distribution, resulting in a significant reduction in blood perfusion It was interesting to note that the artery with an upward orientation had a smaller rate of reduction in blood perfusion. It can be concluded that as for the mild renal coverage after EVAR, renal arteries with downward orientation may have the advantage of reducing the possibility of renal occlusion, while renal arteries with horizontal orientation may increase the unfavorable wall shear distribution. On the other hand, as for serious coverage (≥50%), high risk of renal ischemia remains the main concern for all types of renal arteries due to highly disturbed wall shear distribution would significantly increase regardless of renal orientation.