Computational modelling to optimize the hybrid configuration for hypoplastic left heart syndrome

Area of Science:

• Cardiovascular Physiology
• Pediatric Cardiology
• Medical Engineering

Background:

• Hybrid palliation for hypoplastic left heart syndrome (HLHS) presents challenges including mortality and late ventricular dysfunction.
• Increased ventricular workload and limited coronary perfusion are suspected key factors in adverse outcomes.
• Mathematical modeling offers a method to investigate hemodynamic effects of surgical configurations.

Purpose of the Study:

• To investigate the impact of different hybrid palliation configurations on the demands placed on the single ventricle circulation in HLHS.
• To identify optimal parameters for pulmonary artery banding (PAB) and ductal stenting in hybrid palliation.

Main Methods:

• A multicompartmental Windkessel model simulating hybrid HLH-aortic atresia circulation was employed.
• Ventricular function was represented by time-varying elastance.
• Simulations assessed the effects of varying PAB and ductal stent diameters on hemodynamics, systemic oxygenation, and ventricular energetics.

Main Results:

• Increasing PAB diameter (2.5-4 mm) led to higher Q, diastolic stent backflow, reduced systemic perfusion, and lower diastolic pressures.
• Higher PAB diameters necessitated increased cardiac output and ventricular stroke work to maintain systemic pressure.
• Ductal stent diameters <7 mm significantly reduced systemic flow and increased ventricular stroke work, while diameters ≥7 mm had minimal hemodynamic impact.

Conclusions:

• In this model, larger PAB diameters and ductal stents <7 mm substantially increase single ventricle workload.
• Reduced systemic perfusion and diastolic pressure may compromise myocardial oxygen supply-demand balance.
• Optimal hybrid configuration was determined to be PAB at 3 mm and ductal stent ≥7 mm.