What is the Fontan procedure? 

The Fontan procedure is a complex open-heart surgery used to treat children born with “single ventricle” heart defects. It is the final stage of a three-part surgical journey designed to reroute the body’s blood flow. In a healthy heart, two ventricles pump blood: one to the lungs and one to the body. In a child needing a Fontan, only one ventricle is functional. The Fontan procedure connects the inferior vena cava (the large vein from the lower body) directly to the pulmonary arteries, allowing deoxygenated blood to flow passively to the lungs without being pumped by the heart. 

This surgery does not “fix” the heart to a normal four-chamber structure; instead, it creates a unique “in-series” circulation. After the Fontan, the single working ventricle is reserved solely for pumping oxygen-rich blood to the body, while blood returns to the lungs using the pressure already present in the veins. While it is a life-saving intervention that significantly improves oxygen levels and quality of life, it requires lifelong specialized monitoring to manage the unique physiological demands of “Fontan circulation.” 

What We’ll Discuss in This Article 

• The anatomical transition to a Fontan circulation. 

• The three stages of the surgical pathway (Norwood, Glenn, and Fontan). 

• Why the Fontan procedure is performed at age 2–4 years. 

• Common complications: “Fontan-associated liver disease” and arrhythmias. 

• 2026 clinical data on survival and long-term exercise capacity. 

• Life after Fontan: Activity levels and transition to adult care. 

The Anatomy of the Fontan Circulation 

To understand the Fontan, one must first visualize how the “plumbing” changes. In a normal heart, the right ventricle acts as a dedicated pump for the lungs. In a Fontan heart, that pump is missing or too small. 

By the end of the Fontan procedure, all deoxygenated blood from both the upper body (via the earlier Glenn surgery) and the lower body (via the Fontan) flows directly into the lungs. This means: 

• The Heart’s Load is Reduced: The single ventricle no longer has to pump “mixed” blood; it only pumps oxygenated blood. 

• Cyanosis is Resolved: Because oxygen-poor and oxygen-rich blood no longer mix, the “blue” tint to the skin usually disappears. 

• Passive Flow: Blood flow to the lungs now depends on the pressure in the veins being higher than the pressure in the lungs, rather than a mechanical pulse. 

The Staged Surgical Pathway 

The Fontan is rarely performed as a standalone operation. Because the lungs of a newborn cannot handle the passive flow of a Fontan immediately, the repair is done in three stages to allow the body to adapt. 

Stage	Procedure	Typical Age	Goal
Stage 1	Norwood / Shunt	Days 1–10	Ensures the body gets blood while protecting the lungs.
Stage 2	Glenn Procedure	3 – 6 Months	Connects the upper body vein (SVC) to the lungs.
Stage 3	Fontan Procedure	2 – 4 Years	Connects the lower body vein (IVC) to the lungs.

Long-Term Challenges: “The Fontan Life” 

While the Fontan procedure is a triumph of modern surgery, it creates a “precarious” circulatory balance. Because there is no pump for the lungs, any increase in lung pressure (from smoking, asthma, or altitude) can cause the system to struggle. 

• Liver Health: Because venous pressure is higher than normal, the liver can become congested. This is known as “Fontan-Associated Liver Disease” (FALD). 

• Protein-Losing Enteropathy (PLE): A rare complication where the gut leaks protein due to high venous pressures. 

• Arrhythmias: Surgical scars in the atrium can lead to irregular heart rhythms as the patient enters their 20s or 30s. 

• Plastic Bronchitis: A rare but serious condition where “casts” form in the airways. 

To Summarise 

The Fontan procedure is the final step in a life-saving surgical sequence for children with single-ventricle hearts. By rerouting the body’s venous return directly to the lungs, it restores oxygen levels and protects the single working ventricle from overwork. While it requires a lifetime of careful management and monitoring of other organs like the liver, the Fontan procedure has allowed a generation of children with once-fatal heart defects to grow into active, thriving adults. 

If your child with a Fontan circulation develops sudden swelling in the legs, a persistent cough, or a blue tinge to the lips, call 999 immediately. 

If you notice a sudden decrease in your child’s exercise tolerance or a racing heart rate, contact your specialist cardiac team immediately. 

Authority Snapshot (E-E-A-T Block) 

This article was reviewed by Dr. Stefan Petrov, a UK-trained physician (MBBS) with postgraduate certifications in ACLS and BLS. Dr. Petrov has extensive clinical experience in hospital wards and intensive care units, including the management of complex congenital heart patients throughout the staged surgical journey. His expertise ensures this information on the Fontan procedure is accurate, safe, and aligned with current NHS and BCCA clinical standards. 

Internal Link Suggestions 

• ‘understanding the Glenn procedure’ 

• ‘living with a single-ventricle heart’ 

• ‘liver health in Fontan patients’