The Fontan Circulation: From Ideal to Failing Hemodynamics and Drug Therapies for Optimization

Area of Science:

• Pediatric Cardiology
• Adult Congenital Heart Disease
• Cardiovascular Physiology

Background:

• Fontan palliation results in a unique, complex circulatory state.
• This state is characterized by systemic venous hypertension, nonpulsatile pulmonary blood flow, and low cardiac output.
• These factors contribute to progressive, multisystemic Fontan circulatory failure over time.

Purpose of the Study:

• To review the hemodynamic principles of optimal Fontan physiology and Fontan circulatory failure.
• To discuss the practical aspects of invasive hemodynamic assessment in Fontan patients.
• To explore the role of pharmacologic management in addressing Fontan circulation failure.

Main Methods:

• Review of existing literature on Fontan circulation hemodynamics and failure modes.
• Discussion of invasive hemodynamic assessment techniques relevant to Fontan physiology.
• Analysis of pharmacologic strategies aimed at improving Fontan circulation.

Main Results:

• Fontan circulation failure is a slowly progressive process driven by specific hemodynamic characteristics.
• Accurate hemodynamic assessment is crucial for identifying treatable causes of decline.
• No established pharmacologic guidelines exist, but understanding hemodynamics aids rational drug selection.

Conclusions:

• Optimizing Fontan physiology requires preserving circuit patency, ventricular function, valve function, outflow tract, and pulmonary vascular integrity.
• Pharmacologic management, often complementary to interventions, aims to enhance venous return and reduce filling pressures.
• Hemodynamic assessment and targeted therapies are key to managing Fontan circulatory failure and maintaining cardiac output.