Title : Computational hemodynamic evaluation for postoperative thrombosis risk based on virtual surgery of systemic-to-pulmonary artery shunt
Systemic-to-pulmonary artery shunt is widely used as a palliative operation to treat complex congenital heart disease. Postoperative thrombosis-induced shunt occlusion is a life-threatening complication. Different surgical designs affect the hemodynamic characteristics, which is intimately related to shunt thrombosis. This study aims to explore the effects of different shunt locations and shunt sizes on postoperative hemodynamic parameters related to thrombosis risk, thus to provide reference for preoperative planning and postoperative thrombosis risk assessment. The three-dimensional vascular model was reconstructed based on the patient-specific medical images. A 4mm artificial conduit was interposed virtually between the ascending aorta (or right subclavian artery, or left innominate artery, separately) and pulmonary artery using computer-aided design (CAD). Three virtual models were formed, and named Model 1, Model 2 and Model 3 in sequence. Another two conduits (diameter of 3.5mm and 5mm) were modified on Model 3. Computational fluid dynamics was applied to calculated hemodynamic parameters including wall shear stress (WSS), oscillatory shear index (OSI), particle relative residence time (RRT). The results suggested that the distribution of WSS and OSI of the shunt and pulmonary artery changed with the change of shunt location, but the shunt conduit was always associated with high WSS and high OSI. With the increase of shunt size, the WSS of the shunt decreased and the area of high OSI and high RRT decreased partly, which was not conducive to reducing the potential risk of postoperative thrombosis. The shunt location significantly changes the distribution of hemodynamic parameters related to postoperative thrombosis risk. Comparing with the impacts brought by the change of shunt location, the shunt size has limited effects on the parameters related to thrombosis risk. The evaluation and monitoring of postoperative thrombosis risk cannot be ignored when the shunt size is larger.