Fontan Procedure: Definition and Indications
The Fontan procedure is a palliative cardiac operation that directs systemic venous blood directly to the pulmonary arteries without passing through a ventricle, and is performed when the rudimentary pulmonary ventricle is less than 30% of its normal volume in patients with single-ventricle heart defects. 1
What is the Fontan Procedure?
The Fontan operation creates a unique circulatory system where systemic venous return enters the pulmonary circulation directly, eliminating the need for a subpulmonary ventricle. 1 This fundamentally alters normal cardiovascular physiology by connecting the systemic veins directly to the pulmonary arteries, resulting in the pulmonary and systemic circulations being connected in series without a subpulmonary ventricle. 1
Key Anatomic Features:
- Systemic venous blood flows passively through the lungs without ventricular pumping action 2, 3
- Elevated central venous pressure is an inherent consequence of this circulation 1
- Non-pulsatile pulmonary blood flow characterizes the hemodynamics 2
When is the Fontan Procedure Recommended?
Primary Indication:
The procedure is indicated when the rudimentary pulmonary ventricle is less than 30% of its normal volume, making biventricular repair impossible. 1
Specific Cardiac Defects Treated:
- Tricuspid atresia 1, 3
- Hypoplastic left heart syndrome 3, 4
- Pulmonary atresia with intact ventricular septum 3, 5
- Double-inlet ventricle 3
- Complex double-outlet right ventricle 4
- Other functional or anatomic single ventricle conditions unsuitable for biventricular repair 1
Modern Surgical Modifications
The original atriopulmonary connection is rarely used in the current era due to high rates of atrial arrhythmias and thrombus formation. 1 Current preferred techniques include: 1
- Extracardiac conduit: Bidirectional cavopulmonary anastomosis (BDCPA) plus conduit from inferior vena cava to pulmonary artery 1
- Intra-atrial conduit: BDCPA plus intra-atrial conduit (preferred when ventricular mass would lie on top of an extracardiac conduit, such as in isolated dextrocardia) 1
- Intracardiac lateral tunnel with or without BDCPA 1
- Fenestration option: A communication between systemic venous pathway and left atrium may be created to improve early outcomes 1, 4
Critical Preoperative Requirements
Cardiac catheterization must be performed before initial Fontan surgery to assess suitability of hemodynamics for Fontan physiology. 1 The two factors that consistently predict both early and late outcomes are: 6
- Preserved ventricular function (systemic ventricular ejection fraction ideally >40%)
- Low pulmonary artery pressures and resistance
Expected Outcomes and Long-Term Prognosis
Ten-year survival after Fontan operation is approximately 90%, depending on risk factors present at the time of surgery. 1 However, this is a palliative procedure with significant long-term morbidity. 2, 3
Common Long-Term Complications:
- Atrial arrhythmias and right atrial thrombus (especially with older atriopulmonary connections) 1
- Ventricular dysfunction and systemic edema 1
- Hepatic congestion, dysfunction, fibrosis, and risk of hepatocellular carcinoma 1
- Protein-losing enteropathy (associated with <50% 5-year survival once developed) 1, 6
- Exercise intolerance 2, 3
- Plastic bronchitis 2, 3
- Pulmonary arteriovenous malformations 1
Mandatory Lifelong Follow-Up
All patients after Fontan palliation require lifelong follow-up with at least yearly evaluation by a cardiologist with expertise in adult congenital heart disease (ACHD). 1
Required Annual Surveillance: 1, 6
- Echocardiography or cardiac MRI
- ECG and Holter monitoring
- Exercise testing
- Biochemical and hematological testing (especially liver and renal function)
- Liver imaging (ultrasonography, MRI, or CT) for fibrosis, cirrhosis, and hepatocellular carcinoma screening
Management must be coordinated with a regional ACHD center, with catheterization procedures performed only at centers with ACHD expertise. 1
Critical Pitfall to Avoid:
New-onset atrial tachyarrhythmias must be managed promptly with prevention of thromboembolic events and immediate consultation with an electrophysiologist experienced in congenital heart disease, as this signals potential hemodynamic deterioration requiring comprehensive imaging and possibly cardiac catheterization. 1