Functional analysis of Fontan energy dissipation

Area of Science:

• Cardiovascular fluid dynamics
• Biomedical engineering
• Pediatric cardiology

Background:

• The total cavopulmonary connection (TCPC) is a surgical procedure to redirect venous blood to the lungs in complex congenital heart disease.
• Understanding energy dissipation in the TCPC is crucial for optimizing hemodynamics and patient outcomes.
• Existing models may not fully capture the complex interplay of physiological and anatomical factors influencing energy loss.

Purpose of the Study:

• To formalize and model hydrodynamic energy dissipation in the TCPC.
• To investigate the influence of key flow variables and geometric characteristics on energy loss.
• To develop a clinically useful, predictive model for TCPC energy dissipation.

Main Methods:

• Dimensional analysis was used to formalize energy dissipation.
• A mathematical model was developed based on governing flow variables (cardiac output, flow split, body surface area, Reynolds number).
• In vitro energy loss data from six patient anatomies were used for validation and model development.

Main Results:

• Energy dissipation is a cubic function of pulmonary flow split within the physiological range.
• Non-dimensional energy dissipation depends solely on Reynolds number and geometry.
• Non-dimensional energy dissipation decreases with Reynolds number (Re(-0.25)) and correlates with minimum pulmonary artery area (power law decay, -5/4) at high Reynolds numbers.

Conclusions:

• A simple analytical form for energy dissipation rate in patient-specific TCPCs was established.
• The model accurately captures the effects of cardiac output, flow split, body surface area, Reynolds number, and pulmonary artery size.
• Further research with larger cohorts is needed to include finer geometric details.