Abstract 14301: Investigation of an Injection-Jet Self-Powered Fontan Circulation

Abstract

Introduction: The Fontan circulation is a fragile system in which imperfections at any one of multiple levels may compromise quality of life. Increased inferior vena caval (IVC) pressure itself may play some role in “Fontan failure”. The Fontan circulation is powered with a high speed injection jet shunt (IJS) drawing flow from the aortic arch, balanced by a fenestration to preserve the ratio of pulmonary flow (Qp) to systemic flow (Qs). The high-velocity jet causes flow entrainment, leading to a significant reduction of upstream pressure. We describe a tightly coupled multi-scale lumped parameter/computational fluids dynamics (LPM-CFD) model to validate this hypothesis. Methods: A synthetic 3D CAD model of the fenestrated total cavopulmonary connection (TCPC) was generated, with average dimensions matching those of a 2-4 yo patient. The prescribed cardiac output is of about 2.3L/min. The detailed 3D pulsatile hemodynamics in the fluid domain are modeled as unsteady, turbulent and incompressible. Blood is assumed to be non-Newtonian. Turbulence is approximated using a large eddy simulation (LES) approach. Potential optimal IJS configurations were determined by with a parametric sweep of several geometric design parameters such as TCPC morphology, shunt diameter and location, and fenestration diameter and location. The effects of the IJS implementation on IVC pressure with a fenestration and systemic oxygen saturation were calculated using a tightly coupled LPM-CFD. Results and Discussion: A set of baseline simulations representing a failing Fontan, with elevated IVC pressure (+17.8mmHg). Enlargement of the fenestration to 7 mm results in a 3 mm Hg IVC pressure drop but also significant reduction in systemic oxygen saturation (assuming a 96% pulmonary venous O2 saturation level). Addition of an IJS (2mm nozzle) to this model preserves the IVC pressure drop of 3.2mmHg but improves systemic oxygen saturation with only a small additional volume load to the ventricle (CO/Qs = 1.2). Conclusions: This study demonstrates the potential salutary effect of the IJS on the Fontan circulation. Further exploration of adjustable anatomic and parameters are needed to further reduce IVC pressure and improve systemic saturation.