Computational Hemodynamic Evaluation of Different Surgical Designs of Systemic to Pulmonary Arterial Shunt Under Controlled Pulmonary Flow

Systemic to pulmonary arterial shunt including modified central shunt (MCS) and modified Blalock-Taussig shunt (MBTS) are widely applied surgeries to increase pulmonary perfusion. It's crucial to ensure the pulmonary flow was well-controlled within a reasonable range, since both excessive and insufficient pulmonary perfusion leads to poor prognosis. The pulmonary flow could be well-controlled by selecting various shunt designs, e.g. shunt location and size. However, the hemodynamic performance of different designs is less explored under equivalent and reasonable pulmonary flow. Here, the individualized vascular model was reconstructed. To realize appropriate and equivalent pulmonary flow, three virtual surgeries including 4 mm left MBTS, 4 mm MCS, and 5 mm right MBTS were implemented using computer-aided design (CAD). The postoperative hemodynamic parameters were calculated by computational fluid dynamics (CFD). The results showed the postoperative models had equivalent pulmonary flow. The left MBTS had a better performance in balancing the pulmonary flow distribution. The right MBTS had a lower wall shear stress (WSS) and time-averaged WSS region in the shunt. The flow vortex and shear stress fluctuations were hardly avoidable in pulmonary arteries. In conclusion, the appropriate and equivalent pulmonary flow could be well realized by a larger-sized shunt when changing the shunt location of MBTS to the third aortic branch, compared with the MCS. The pulmonary flow distribution is greatly affected by the shunt location and vascular anatomy. The assessment and monitoring of thrombosis risk is requisite during perioperative management and postoperative follow-up no matter what shunt design is applied.