Failure of the fontan circulation

Area of Science:

• Cardiovascular Surgery
• Pediatric Cardiology
• Congenital Heart Disease

Background:

• The Fontan circuit is a palliative surgical procedure for single-ventricle congenital heart defects.
• It establishes a direct connection between systemic veins and pulmonary arteries, bypassing the ventricle.
• This creates a 'neoportal system' but results in chronic systemic venous congestion and reduced cardiac output.

Purpose of the Study:

• To elucidate the hemodynamic consequences of the Fontan circuit.
• To understand the impact of altered hemodynamics on cardiac function and end-organ health.
• To describe the progressive nature of Fontan-associated circulatory failure.

Main Methods:

• Hemodynamic analysis of the Fontan circulation.
• Review of clinical outcomes and pathophysiology in Fontan patients.
• Assessment of ventricular function (systolic and diastolic) in the Fontan context.

Main Results:

• The Fontan circuit leads to a chronic state of systemic venous congestion and decreased cardiac output.
• The ventricle loses control over output and venous pressures, contributing to hemodynamic burden.
• Abnormal hemodynamics can cause significant end-organ damage, including liver cirrhosis, protein-losing enteropathy, and plastic bronchitis.

Conclusions:

• The Fontan circuit, while enabling oxygenation, imposes a significant hemodynamic burden.
• Progressive Fontan failure is characterized by increased vascular resistance and ventricular filling pressures.
• Long-term management requires addressing the consequences of chronic venous congestion and low flow states.