Fluid–structure interaction simulations of the Fontan procedure using variable wall properties

Abstract

Children born with single ventricle heart defects typically undergo a staged surgical procedure culminating in a total cavopulmonary connection (TCPC) or Fontan surgery. The goal of this work was to perform physiologic, patient-specific hemodynamic simulations of two post-operative TCPC patients by using fluid-structure interaction (FSI) simulations. Data from two patients are presented, and post-op anatomy is reconstructed from MRI data. Respiration rate, heart rate, and venous pressures are obtained from catheterization data, and inflow rates are obtained from phase contrast MRI data and are used together with a respiratory model. Lumped parameter (Windkessel) boundary conditions are used at the outlets. We perform FSI simulations by using an arbitrary Lagrangian-Eulerian finite element framework to account for motion of the blood vessel walls in the TCPC. This study is the first to introduce variable elastic properties for the different areas of the TCPC, including a Gore-Tex conduit. Quantities such as wall shear stresses and pressures at critical locations are extracted from the simulation and are compared with pressure tracings from clinical data as well as with rigid wall simulations. Hepatic flow distribution and energy efficiency are also calculated and compared for all cases. There is little effect of FSI on pressure tracings, hepatic flow distribution, and time-averaged energy efficiency. However, the effect of FSI on wall shear stress, instantaneous energy efficiency, and wall motion is significant and should be considered in future work, particularly for accurate prediction of thrombus formation.

Computational fluid dynamics in Fontan patients to evaluate power loss during simulated exercise

“…Considering the limited pulsatility in the Fontan circulation, the common assumptions of rigid walls and steady flow are valid. Furthermore, Long et al 25 showed in two patients that the time-averaged power efficiencies calculated with rigid walls were only 1.5% lower than that calculated with compliant walls.…”

Hemodynamic effects of implanting a unidirectional valve in the inferior vena cava of the Fontan circulation pathway: an in vitro investigation

“…Despite favorable short-term outcomes and lowered mortality rates (1,13,14,17,19), numerous long-term complications have been reported (8) including ventricular dysfunction and limited ventricular power (28), increased pulmonary vascular resistance (4), arrhythmias (6), severely diminished exercise capacity (21,24,31), protein losing enteropathy (22), and hepatic complications (4,9). Although considerable advances have been made in understanding total cavopulmonary connection (TCPC) hemodynamics (16,18,20,29,30) and in pre-operative surgical planning (26), therapies for improving cardiac hemodynamics and averting end-stage complications in the growing population of Fontan patients are currently lacking.…”

“…Despite favorable short-term outcomes and lowered mortality rates (1,13,14,17,19), numerous long-term complications have been reported (8) including ventricular dysfunction and limited ventricular power (28), increased pulmonary vascular resistance (4), arrhythmias (6), severely diminished exercise capacity (21, 24, 31), protein losing enteropathy (22), and hepatic complications (4, 9). Although considerable advances have been made in understanding total cavopulmonary connection (TCPC) hemodynamics (16,18,20,29,30) and in pre-operative surgical planning (26), therapies for improving cardiac hemodynamics and averting end-stage complications in the growing population of Fontan patients are currently lacking.Of specific interest to this study are the effects of Fontan circulation on the liver and gastrointestinal (GI) tract. The altered series arrangement of the systemic and pulmonary circulations in the Fontan patient, together with the lack of a functional right heart to pump blood to the lungs, predisposes the systemic veins to higher pressures and in turn elevates hepatic venous pressure.…”

Patient-Specific Surgical Planning, Where Do We Stand? The Example of the Fontan Procedure

“…Long et al 27 conducted an FSI study for two patient-specific extracardiac TCPC, dividing the domain of interest into multiple regions to account for the different material properties and wall thicknesses of the veins, arteries and artificial Fontan pathway. Comparing FSI and rigid wall results, local differences were noted in WSS but not in global measures, such as time averaged pressures, energy efficiency, or hepatic flow distribution.…”