Hemodynamics of different surgical subclavian revascularization morphologies for thoracic endovascular aortic repair

Background and Objective

Carotid-subclavian bypass (CSB) and subclavian-carotid transposition (SCT) are mainstream surgical left subclavian artery (LSA) revascularization methods. However, surgical selection of CSB and SCT morphological configurations mainly depends on surgeons’ experience, lacking objective data basis.

Methods

Geometries with 28 configurations, including length, diameter, angle, and anastomotic direction for prosthetic conduit and transposed LSA, were constructed. Numerical simulations were performed to evaluate CSB and SCT outcomes by hemodynamic parameters such as pressure drop, flow rate, energy loss and wall shear stress related indicators.

Results

After CSB, enlarging prosthetic conduit diameter (6 to 10 mm) increases flow rate by 36.64 %, suggesting larger diameter enhances LSA patency. However, when diameter exceeds 9 mm, the relative residence time rises by 35.29 %, demonstrating oversized diameter increases the risk of thrombosis. Compared to 5 mm, prosthetic conduit at 15 mm displays a 7.80 % flow rate reduction, indicating longer conduit causes greater flow resistance. For varying angles, prosthetic conduit perpendicular to left common carotid artery (LCCA) shows the least energy loss. Conduit tilted downward from the vertical position shows higher flow rate than the upward during systole (210.35 vs. 106.34 ml/min). However, 10 % blood flow in downward conduit reflows cyclically during diastole, resulting in the reduced cycle-averaged flow rate of downward conduit compared to that of the upward (53.21 vs. 58.42 ml/min). After SCT, configurations with smaller angles between LCCA and LSA show better hemodynamic performance, with a maximum flow rate variation of 30.34 % in LSA from 50° to 110°.

Conclusions

Configurations with moderately smaller diameter, reduced length of prosthetic conduit and aligned anastomosis towards LCCA blood flow result in better LSA revascularization outcomes. The findings are supportive for optimizing CSB and SCT configurations.