The Fontan Procedure and Its Hepatic Complications: Understanding Fontan-Associated Liver Disease (FALD)

Mayta
Oct 8
4 min read

Updated: 6 days ago

1️⃣ What Is the Fontan Procedure?

The Fontan procedure is a palliative cardiac surgery performed for children with single-ventricle congenital heart defects, where only one ventricle is capable of supporting systemic circulation.

➤ Purpose:

To separate systemic and pulmonary circulation in patients who cannot undergo a biventricular repair.

➤ Indications:

Common congenital heart diseases requiring Fontan include:

Tricuspid atresia
Hypoplastic left heart syndrome (HLHS)
Double inlet left ventricle
Pulmonary atresia with intact ventricular septum
Unbalanced atrioventricular septal defect

2️⃣ The Principle of the Fontan Circulation

In a normal heart, the right ventricle pumps deoxygenated blood to the lungs, and the left ventricle pumps oxygenated blood to the body.But in a single-ventricle heart, one ventricle must handle both circuits, which is not sustainable.

➤ The Fontan Solution:

The Fontan operation bypasses the right ventricle by routing systemic venous blood directly into the pulmonary arteries, allowing passive flow into the lungs.

🩸 Surgical Concept:

Systemic veins (SVC + IVC) → directly connected to pulmonary arteries
The single ventricle → pumps only oxygenated blood to systemic circulation

Thus, the Fontan circulation is non-pulsatile, passive, and depends entirely on pressure gradients between the systemic venous and pulmonary arterial systems.

3️⃣ Why We Do It (Clinical Necessity)

The Fontan procedure is not curative — it is a palliative repair designed to: ✅ Separate oxygenated and deoxygenated blood ✅ Improve systemic oxygen saturation (reduces cyanosis) ✅ Reduce ventricular volume overload ✅ Allow better growth and exercise tolerance ✅ Increase survival into adulthood

Without this surgery, children with single-ventricle physiology typically die early from hypoxia or heart failure.

4️⃣ The Downside: The Fontan Physiology

While life-saving, the Fontan circulation creates chronic systemic venous hypertension and low cardiac output.

⚠️ Key Hemodynamic Features:

No sub-pulmonary pump (right ventricle bypassed)
Passive pulmonary blood flow → dependent on low PVR
Chronically elevated central venous pressure (CVP ≈ 12–18 mmHg)
Reduced preload → limited cardiac output

This non-physiologic circulation places constant stress on organs, especially the liver, lymphatics, and intestines.

5️⃣ Chronic Hepatic Congestion and Fontan-Associated Liver Disease (FALD)

➤ What is FALD?

Fontan-Associated Liver Disease (FALD) is a spectrum of chronic liver injury resulting from long-standing elevated systemic venous pressure and low cardiac output after a Fontan operation.It is essentially a form of congestive hepatopathy progressing to fibrosis and cirrhosis.

6️⃣ Pathophysiology of FALD

🧬 Step-by-Step Mechanism:

Chronically elevated central venous pressure (CVP)→ Causes hepatic venous congestion because the hepatic veins drain into the systemic venous system.
Sinusoidal congestion and dilatation→ Leads to hepatocyte atrophy around the central veins (centrilobular necrosis).
Chronic hypoxia and low cardiac output→ Reduce hepatic perfusion and oxygen delivery, worsening injury.
Repeated injury and repair cycle→ Triggers fibrosis starting in zone 3 (centrilobular), extending to bridging fibrosis.
Development of nodular regenerative hyperplasia (NRH)→ From uneven perfusion and chronic hypoxia, producing a cirrhotic pattern even without classic portal hypertension.
Over time, this progresses to:
- Cardiac cirrhosis
- Portal hypertension
- Ascites
- Hepatocellular carcinoma (HCC) risk

⚠️ Important Note:

Unlike viral or alcoholic cirrhosis, FALD occurs even with normal hepatic enzymes. Thus, liver fibrosis may progress silently for 10–20 years after the Fontan procedure.

7️⃣ What Happens Next — Clinical Course

Stage	Description	Findings
Early FALD	Hepatic congestion & mild fibrosis	Mildly elevated LFTs, hepatomegaly
Established FALD	Bridging fibrosis & NRH	Portal hypertension, splenomegaly, ascites
End-stage FALD	Cirrhosis ± HCC	Decompensated liver disease

8️⃣ How to Detect and Monitor FALD Early

🧪 Screening & Diagnostic Tools

Test	Purpose
Liver function tests (LFTs)	May remain normal until advanced disease
Ultrasound with Doppler	Detects hepatomegaly, congestion, ascites
Elastography (FibroScan)	Measures liver stiffness (fibrosis proxy)
MRI with contrast	Identifies fibrosis pattern & regenerative nodules
Liver biopsy	Gold standard, but risky — reserved for unclear cases
Alpha-fetoprotein (AFP)	HCC surveillance

9️⃣ Can We Prevent or Reverse FALD?

Unfortunately, true prevention is not possible, but progression can be slowed with proper management and early detection.

🛡️ Strategies to Protect the Liver in Fontan Patients:

1. Optimize Fontan Hemodynamics

Maintain low pulmonary vascular resistance (PVR)
- Avoid hypoxia, hypercapnia, acidosis
- Treat respiratory infections promptly
Avoid dehydration (reduces venous flow)
Manage arrhythmias and heart failure aggressively

2. Control Venous Congestion

Use diuretics carefully to prevent fluid overload but avoid excessive volume depletion.
ACE inhibitors or beta-blockers may be used to optimize cardiac function.

3. Anticoagulation

Reduces risk of hepatic and systemic thrombosis, which can worsen hepatic congestion.

4. Regular Surveillance

Liver ultrasound every 6–12 months
Elastography every 1–2 years
AFP + imaging for HCC screening (especially after 10 years post-Fontan)

5. Multidisciplinary follow-up

Involves cardiology, hepatology, and radiology teams.

6. Liver transplantation or combined heart-liver transplant

Indicated in end-stage FALD or Fontan failure with cirrhosis.

🔟 Key Takeaways

Concept	Summary
Fontan circulation	Routes venous blood directly to lungs, bypassing right ventricle
Hemodynamic feature	High venous pressure, low cardiac output
FALD	Chronic congestive hepatopathy → fibrosis → cirrhosis
Main driver	Chronic hepatic congestion and hypoperfusion
Prevention	Not fully preventable, but progression can be delayed
Surveillance	Lifelong liver imaging and functional monitoring
Treatment	Optimize Fontan physiology; transplant for end-stage disease

Clinical Pearl

“Fontan-associated liver disease is the inevitable price of Fontan physiology — not a complication of surgery but a consequence of survival.”