Fontan conduit cross-sectional area and relationship to exercise performance

Area of Science:

• Pediatric Cardiology
• Congenital Heart Disease
• Cardiovascular Physiology

Background:

• The extracardiac (EC) Fontan conduit can become inadequate with growth, potentially limiting exercise capacity.
• Assessing the relationship between conduit size and functional outcomes is crucial for managing Fontan patients.

Purpose of the Study:

• To evaluate the association between EC-Fontan conduit cross-sectional area (CSA), indexed to body surface area (BSA), and exercise performance.
• To determine if conduit size is an independent predictor of exercise capacity in Fontan survivors.

Main Methods:

• Cross-sectional analysis of data from the FORCE registry.
• Cardiac magnetic resonance imaging (CMR) and cardiopulmonary exercise testing (CPET) data were collected within one year.
• Multivariable linear regression models were used to assess the association between Fontan CSA/BSA and peak oxygen consumption (ppVO₂), adjusting for known predictors.

Main Results:

• In 324 patients with adequate imaging and testing, smaller minimum and length-averaged Fontan CSA/BSA were positively associated with higher ppVO₂.
• Each mm²/m² increase in minimum CSA/BSA correlated with a 0.08% increase in ppVO₂ (p<0.001).
• Fontan CSA/BSA was not significantly associated with resting cardiac function measures.

Conclusions:

• Reduced EC-Fontan conduit size indexed to BSA is independently associated with diminished exercise capacity.
• Conduit size is a significant factor influencing functional outcomes in patients with EC-Fontan anatomy.