Title : Computational hemodynamic study of systemic-to-pulmonary arterial shunt with different design of conduit position.
Object: Different types of systemic-to-pulmonary arterial shunts are used as the palliative treatment for the first-staged procedure of congenital heart disease (CHD). Although the surgical techniques improved over the years, the position of the conduit implanted between the systemic circulation and the pulmonary artery is still one of the controversial issues. In the present study, we investigate the hemodynamic features in four types of systemic-to-pulmonary arterial shunts with various implantation positions. Methods: A modified central shunt with a conduit of 4 mm in diameter was reconstructed based on the patient-specific medical images. The technique of computer-aided design (CAD) was employed to perform the virtual procedures according to the initial vascular structures. The geometric models of modified Blalock-Taussig (mB-T) shunt, Melbourne shunt as well as central shunt with a relatively long U-shaped conduit were acquired. Pulsatile simulations and the hemodynamic analysis were done to capture the physiological information of blood flow using the method of computational fluid dynamics (CFD). Results: The local hemodynamic features in different models were demonstrated by pressure, streamlines, wall shear stress (WSS), blood flow distribution and energy loss. The pulmonary flow distribution changed as the conduit position varied. But the flow distribution between bilateral lungs was more balanced in the mB-T shunt and modified central shunt with a short conduit, compared to that in the U-shaped central shunt and Melbourne shunt. Relatively higher pressure drops and WSS were generated in almost all the conduits. Conclusion: The mB-T shunt exhibits proper pulmonary perfusion and balanced pulmonary flow distribution. The conduit implanted between the first branch of aortic arch and the pulmonary artery branch, is associated with better performance in hemodynamics. The numerical simulation is a useful approach for the investigation of local hemodynamics and the evaluation of the different types of systemic-to-pulmonary arterial shunts.