Relation Between Exercise Capacity and Extracardiac Conduit Size in Patients with Fontan Circulation

Area of Science:

• Pediatric Cardiology
• Congenital Heart Disease
• Hemodynamics

Background:

• Fontan circulation physiology presents unique challenges due to the absence of a subpulmonary ventricle, leading to limited preload.
• Extracardiac conduits are commonly used in Fontan procedures, and their size is hypothesized to influence hemodynamic function and patient outcomes.

Purpose of the Study:

• To investigate the relationship between extracardiac conduit size relative to body surface area (BSA) and exercise capacity in patients with Fontan circulation.
• To identify an optimal conduit size per BSA that maximizes exercise performance.

Main Methods:

• Retrospective review of 677 patients with Fontan circulation, with 150 patients meeting inclusion criteria.
• Exclusion criteria included other Fontan types, low oxygen saturation, protein-losing enteropathy, and inadequate exercise tests.
• Analysis correlated conduit size per BSA with exercise capacity parameters (predictive peak VO2, VE/VCO2) using a quadratic model, controlling for other factors.

Main Results:

• Conduit size per BSA showed a significant curved correlation with predictive peak VO2 and VE/VCO2.
• Patients with a conduit size of approximately 12.5 mm/m² BSA demonstrated the best exercise capacity.
• Both larger and smaller conduit sizes were associated with attenuated exercise capacity compared to the optimal size.

Conclusions:

• Conduit size relative to BSA is a critical factor influencing exercise capacity in patients with extracardiac Fontan circulation.
• An optimal conduit size of approximately 12.5 mm/m² BSA appears to maximize exercise performance.
• Careful consideration of conduit sizing during surgical planning may improve long-term functional outcomes for Fontan patients.