Hi, @sascha2432. Thank you for participating in our #AsktheMayoMom broadcast! We're sorry we didn't get time to answer your question live. Here's a response from Dr. Dearani: This is a well-documented late problem following the Fontan procedure. A knowledgeable cardiologist should be involved with medical management and gathering imaging and other medical testing to determine whether there is a role for a cath lab intervention, or surgery, or transplantation in some instances.