Computational fluid dynamics in Fontan patients to evaluate power loss during simulated exercise

Area of Science:

• Cardiovascular Physiology
• Biomedical Engineering
• Pediatric Cardiology

Background:

• Exercise intolerance is a significant issue for patients with total cavopulmonary connection (TCPC).
• Increased power loss (Ploss) within the TCPC is hypothesized to contribute to reduced exercise performance.

Purpose of the Study:

• To investigate the role of Ploss within the TCPC during simulated exercise conditions.
• To analyze Ploss in patient-specific TCPC models under varying flow rates.

Main Methods:

• Cardiac MRI (CMR) was used to capture flow dynamics at rest and during dobutamine-induced stress.
• 3D TCPC reconstructions from CMR data enabled computational fluid dynamics (CFD) simulations.
• Simulated exercise involved a twofold increase in inferior caval vein (IVC) flow.

Main Results:

• Mean Ploss was significantly higher in extracardiac conduit (ECC) patients compared to intra-atrial lateral tunnel (ILT) patients across all conditions.
• Ploss increased substantially under simulated exercise (dobutamine and twofold IVC flow) compared to rest.
• An exponential correlation was observed between cardiac index and Ploss in both ILT and ECC groups.

Conclusions:

• Ploss within the TCPC increases with simulated exercise, influenced by TCPC anatomy and surgical technique.
• ILT patients consistently demonstrated lower Ploss than ECC patients.
• No direct relationship was established between Ploss and measured exercise capacity.