The goal of this observational study is to assess the clinical impact following Fontan stent placement for extracardiac Fontan conduit (EFC) stenosis in patients with single-ventricle Fontan-palliated patients ages 12-21 years old.
The main question it aims to:
-Assess changes in exercise capacity by cardiopulmonary exercise testing and liver stiffness assessed by shear wave elastography before and after EFC stenting.
Participants will undergo two cardiopulmonary exercise tests and three shear wave elastography scans.