Assisted Fontan procedure: animal and in vitro models and computational fluid dynamics study

Area of Science:

• Cardiovascular Surgery
• Biomedical Engineering
• Hemodynamics

Background:

• The Fontan connection is a surgical procedure to manage single-ventricle congenital heart defects.
• Optimizing pulmonary blood flow after Fontan surgery is crucial for long-term outcomes.
• Intermittent compression of the Fontan conduit is being explored as a method to enhance circulation.

Purpose of the Study:

• To evaluate the efficacy of intermittent compression of the Fontan conduit using latissimus dorsi (LD) muscle or an inflatable cuff.
• To assess the impact of compression on pulmonary artery pressure and blood flow.
• To investigate the potential of computational fluid dynamics (CFD) and mathematical modeling in predicting flow changes.

Main Methods:

• In vivo study involving pigs with LD-wrapped Fontan conduits.
• In vitro mock circuit experiments with an inflatable cuff applying intermittent compression.
• Computational fluid dynamics (CFD) simulations to model flow dynamics.
• Measurements of pressure and flow rates under various conditions.

Main Results:

• In vivo: LD compression decreased pulmonary artery pressure by 7% and increased flow by 2%.
• In vitro: Increasing driving pressure enhanced flow, but overall pulmonary flow decreased during compression.
• CFD: 13.0 mmHg compression increased total pulmonary flow by 4.9% and peak flow by 92%.

Conclusions:

• Intermittent compression of the Fontan conduit presents a potential strategy for improving pulmonary blood flow.
• Experimental results were confounded by intermittent flow restriction.
• Mathematical modeling indicates that lower compression pressures may enhance pulmonary flow, warranting further investigation.