Simulation of aortopulmonary collateral flow in Fontan patients for use in prediction of interventional outcomes

Summary Purpose Patients with complex congenital heart disease may need to be converted to a Fontan circulation with systemic venous return surgically connected to the pulmonary circulation. These patients frequently form aortopulmonary collaterals ( APC ), that is arterial inflows to the pulmonary artery vascular tree. The aim of this study was to develop a method to calculate the effect of APC on the pulmonary flow distribution based on magnetic resonance imaging ( MRI ) measurements and computational fluid dynamics simulations in order to enable prediction of interventional outcomes in Fontan patients. Methods Patient‐specific models of 11 patients were constructed in a 3D‐design software based on MRI segmentations. APC flow was quantified as the difference between pulmonary venous flow and pulmonary artery flow, measured by MRI . A method was developed to include the modulating effect of the APC flow by calculating the patient‐specific relative pulmonary vascular resistance. Simulations, including interventions with a Y‐graft replacement and a stent dilatation, were validated against MRI results. Results The bias between simulated and MRI ‐measured fraction of blood to the left lung was 2·9 ± 5·3%. Including the effects of the APC flow in the simulation ( n  = 6) reduced simulation error from 9·8 ± 7·0% to 5·2 ± 6·3%. Preliminary findings in two patients show that the effect of surgical and catheter interventions could be predicted using the demonstrated methods. Conclusions The work demonstrates a novel method to include APC flow in predictive simulations of Fontan hemodynamics. APC flow was found to have a significant contribution to the pulmonary flow distribution in Fontan patients.