Purpose or Case Report: The Fontan operation, used to palliate single ventricle congenital heart disease, increases venous pressure in the liver and is associated with Fontan associated liver disease (FALD), for which liver fibrosis is the final common pathway. Elastography (ultrasound [US] or MRI) can be used to non-invasively measure liver stiffness associated with liver fibrosis. However, these measures are confounded in Fontan patients due to venous congestion. The purpose of this study was to prospectively document the stiffening effect of passive hepatic congestion following the Fontan operation and track changes in liver stiffness over the post-operative period.
Methods & Materials: This was a prospective study conducted under IRB approval with written informed consent. Patients scheduled for the Fontan operation underwent baseline liver US with 2D shear wave elastography (SWE) prior to surgery. Patients then underwent follow-up SWE at 24-96h post-Fontan, hospital discharge (6-8 days post-Fontan), 6-months, and 1-year. For each SWE examination, 10 shear wave speed measurements were obtained in the right hepatic lobe.

Descriptive statistics were used to summarize population characteristics. Patient shear wave speed (SWS) data were expressed as medians (mSWS).
Results: 23 patients (78% male) were imaged 24-96h postoperative, 20 were imaged at discharge, 15 were imaged at 6-months, and 7 were imaged at 1-year. Mean age at baseline US was 3.8±0.9 years. The most common cardiac lesions were: hypoplastic left heart syndrome (n=11) and tricuspid atresia (n=8). All but two patients underwent extracardiac conduit Fontan.

Population median mSWS was 1.28 m/s at baseline, increased to 2.27 m/s postoperative, and remained relatively stable thereafter (1.92 m/s at discharge, 2.17 m/s at 6-months, and 2.02 m/s at 1-year). Median mSWS change from baseline was 1.02 m/s postoperative, 0.73 m/s at discharge, 0.77 m/s at 6 months, and 0.8 m/s at 1 year (all statistically significant, p<0.0001). Changes in mSWS from discharge to 6 and 12 month post-Fontan ultrasound were not statistically significant. There was no significant difference in mSWS at baseline based on cardiac lesion and no significant difference in change in mSWS between baseline and follow up based on surgery type.
Conclusions: Fontan palliation of single ventricle congenital heart disease results in immediate and sustained postoperative increases in liver stiffness measured by US 2D SWE that persist for at least one year.