Session S74.4

Hemodynamic Assessment of Virtual Surgery Options for a Failing Fontan Using Lumped Parameter Simulation

CM Haggerty*, DA de Zelicourt, KS Sundareswaran, K Pekkan,
MA Fogel, AP Yoganathan

Georgia Institute of Technology
Atlanta, GA, USA

Image processing, virtual anatomy-editing tools, and computational fluid solvers offer unique opportunities for pre-operative modeling and evaluating surgical repairs of congenital heart disease, such as single ventricle defects. In a recent single ventricle case, three patient-specific Fontan models were proposed and evaluated using CFD to alleviate bilateral pulmonary arteriovenous malformations. To better understand the effect of these options on the rest of the patient physiology, we extend this work by also performing lumped parameter simulations with an electrical circuit analog of the cardiovascular system.
Arteries, veins, and heart chambers were treated as time-dependent compliance chambers with precise values obtained from literature. Lumped resistances were prescribed for the systemic and pulmonary circuits and were acquired through catheterization. The Fontan connection was modeled as a single resistor between the circuits with the exact value derived from CFD. Pressure and flow conditions were then determined by iteratively solving a set of differential equations until convergence.
The predicted range of resistance values through the Fontan connections was 0.66-1.30 Wood Units for the resting conditions. These values resulted in pressure and flow values similar to those measured by catheterization. Large decreases in cardiac output (12%) and systemic arterial pressure (9%) (i.e., decreased ventricular output power), and a slight increase in mean systemic venous pressure (2%) were seen between the most efficient and least efficient models. These results were further exacerbated under simulated exercise conditions due to the substantial nonlinear increases in connection resistance. Overall, an intra-atrial option with low resting resistance (0.73 Wood Units) and an even hepatic flow split was recommended as the best option for this patient. In summary, virtual surgery and performance prediction tools, once clinically implemented, have the potential to reduce bypass time, improve hemodynamic outcome and eliminate trial-and-error during complex cardiac surgeries.

(Abstract Control Number: 117)