Blalock-Taussig (BT) Shunt is a palliative surgical procedure used during a Norwood surgery on a new born baby suffering from cyanotic heart defects. The BT Shunt can increase blood flow in patients’ pulmonary artery which can ease the “Blue Baby Syndrome”. Currently used BT Shunts do not produce a balanced flow distribution to the pulmonary arteries (PAs) that can cause high wall shear stress (WSS) and blood flow separation which may result in blood clots. A modified BT Shunt was designed to partially solve this problem. In our previous work \[1\], the modified BT Shunt was shown by numerical simulations to have the ability to better control the flow distribution between Innominate Artery (IA) and PA with lower and gradually varying WSS and with improved flow balance in the pulmonary artery at the T-junction of the shunt.

The goal of this paper is to computationally evaluate the flow in the modified BT shunt model between innomate and pulmonary artery using a  patient specific aorta model. The simulations were performed using the commercial CFD software ANSYS Fluent. The improved modified BT shunt is connected between IA and PA. A change in the length of the shunt can be made to fit under different conditions of actual patients. In numerical simulations, a full geometry of patient’s aorta is considered. Results for different lengths of the shunt are compared to determine the length that generates the lowest WSS and improved flow distributionto the the PAs. It was found that the length of nearly 26mm creates lower WSS and flow rate difference between two sides of PA from the T-junction of shunt attachment on PA. A sophisticated model was created using Solidworks and Blender to create the realistic geometry which included the modified BT shunt. The numerical simulations provide details of the flow field including velocity and pressure field, WSS, flow separation, and blood damage. Several parameters in shunt design weigh heavily in reducing the thrombosis. This study demonstrates how CFD can be effectively utilized in the design of a medical device such as BT shunt to improve the clinical outcomes in patients.

\[1\] T. Hess*, *R.K. Agarwal and* *D. Hoganson, “Numerical Simulation and Optimization of Blalock-Taussing Shunt,” AJKFluids2019-4784, Proceedings of the ASME-JSME-KSME 2019, 8th Joint Fluids Engineering Conference, AJKFluids2019, July 28-August 1, 2019, San Francisco, CA, USA.


Cfd Evaluation of Blood Flow in an Improved Blalock-Taussing Shunt Using Patient Specific Geometries

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