Fontan-Associated Liver Disease (FALD) is a chronic condition affecting individuals who have undergone the Fontan procedure for complex single-ventricle congenital heart defects. This procedure, a final stage of palliation, reroutes systemic venous blood flow directly to the pulmonary arteries without a subpulmonary ventricle. FALD encompasses a wide spectrum of liver abnormalities, including progressive fibrosis and cirrhosis, resulting from this unique circulatory environment. Nearly all patients with this circulation develop some degree of liver congestion and subsequent fibrosis over time, making it a highly prevalent complication requiring long-term monitoring. FALD can progress to end-stage liver failure and liver cancer, significantly affecting quality and length of life.
How Fontan Circulation Leads to Liver Changes
The underlying cause of FALD is the non-pulsatile blood flow inherent to the Fontan circulation, resulting from the absence of a dedicated pumping chamber for the lungs. This leads to a permanently elevated systemic Central Venous Pressure (CVP) because blood must passively flow through the lungs. This increased pressure transmits backward through the inferior vena cava and into the hepatic veins, causing chronic passive congestion of the liver.
This constant, high-pressure backup leads to persistent swelling and stretching of the liver’s sinusoids. Congestion impairs the liver’s ability to drain blood effectively, causing hypoxia, especially in the central zones of the liver lobules. The combination of chronic congestion and hypoxia triggers cellular injury, activating liver cells that produce scar tissue.
Over time, this results in the accumulation of scar tissue (fibrosis), which gradually replaces healthy liver tissue. As fibrosis progresses, it disrupts the liver’s structure and function, eventually leading to cirrhosis. Time elapsed since the Fontan procedure is the most significant factor predicting the severity of this scarring.
Recognizing and Diagnosing FALD
FALD is often clinically silent, meaning patients may not experience noticeable symptoms until the disease is significantly advanced. When symptoms appear, they can be subtle, such as chronic fatigue, or signs of advanced disease, like abdominal swelling (ascites) or an enlarged spleen. Due to this lack of early symptoms, routine surveillance is necessary to detect FALD before complications arise.
Biochemical Markers
Initial screening often involves blood tests, but these biochemical markers can be misleading in FALD. Liver function tests (LFTs) like ALT and AST may remain normal even when advanced fibrosis is present. However, an elevation in gamma-glutamyl transpeptidase (GGT), a marker associated with bile duct injury, is a common early finding in Fontan patients.
Non-invasive Imaging
Non-invasive imaging modalities are the preferred method for monitoring the liver’s structure and stiffness. Abdominal ultrasound is a standard tool used to check for signs of chronic congestion, such as an irregular liver surface or an enlarged spleen. Magnetic Resonance Imaging (MRI) provides detailed structural images and detects liver nodules, which carry a risk of developing into cancer.
A specialized type of MRI, Magnetic Resonance Elastography (MRE), accurately measures liver stiffness, correlating with the degree of fibrosis. Although MRE is a strong non-invasive indicator, liver biopsy remains the gold standard for precisely staging fibrosis severity. Biopsy is invasive and typically reserved for cases where non-invasive tests are inconclusive, or when liver cancer or another distinct pathology is suspected.
Current Management Strategies
The primary goal of managing FALD is to slow its progression and prevent severe complications by optimizing the function of the Fontan circulation. Optimizing Fontan Hemodynamics means reducing the elevated Central Venous Pressure, the main driver of liver injury. This involves treating issues that hinder blood flow to the lungs, such as arrhythmias or problems with single-ventricle function.
Medical Therapies
Medical therapies manage the consequences of chronic congestion and liver dysfunction. Diuretics are prescribed to manage fluid retention and reduce overall blood volume, thereby lowering systemic venous pressure. Anticoagulation therapy is used to mitigate the increased risk of blood clot formation within the sluggish Fontan circulation, which can impede blood flow and worsen congestion.
As the disease advances, complication management becomes crucial. This includes screening for and managing portal hypertension, which can lead to esophageal varices. Regular endoscopic screening for varices may be performed, and medications can be given to reduce pressure in the portal system.
Surgical Intervention
For patients who develop end-stage liver disease or cancer that cannot be managed otherwise, surgical intervention is considered. The most definitive treatment for advanced FALD is often a Combined Heart and Liver Transplantation. This dual procedure addresses the underlying cardiac issues simultaneously and represents the final option for patients with irreversible organ failure.
The Importance of Long-Term Surveillance
Given the progressive nature of FALD, lifelong, coordinated care is necessary to monitor the condition and intervene early. Management requires a Multidisciplinary Care team, including cardiologists specializing in congenital heart disease and hepatologists specializing in liver disease. This collaboration ensures treatment focuses on both the liver and optimizing overall cardiac function.
A regular screening schedule is essential for early detection of disease progression or the development of liver nodules, including cancer. Adults typically undergo blood work and liver imaging, such as ultrasound or MRE, every one to two years. For patients diagnosed with advanced disease or cirrhosis, monitoring frequency is often increased to every six months to screen for hepatocellular carcinoma.
The risk and severity of fibrosis increase with the number of years since the Fontan procedure. However, early identification of worsening fibrosis allows for timely adjustments to medical management, potentially slowing the disease trajectory. Lifestyle factors also support Fontan health and liver function, including maintaining a healthy weight and following an approved exercise regimen.