Abstract 15233: Hybrid Procedure for Hypoplastic Left Heart Syndrome Has Less Advantage on Ventricular Energetics Compared to the Norwood Procedure with Right Ventricle to Pulmonary Artery Shunt: An In-Silico Analysis
Introduction: To reduce surgical invasions of the Norwood procedure, a hybrid procedure, bilateral pulmonary artery banding (PAB) combined with ductal stenting, has recently been conducted as a stage I palliation for hypoplastic left heart syndrome. However, it remains unclear whether the hybrid procedure has an advantage on ventricular energetics. To clarify this, we performed a theoretical analysis using computational models.
Methods: Computational models of cardiovascular systems of hybrid procedure and the Norwood procedure with systemic-to-pulmonary artery (SPA) shunt and right ventricle to pulmonary artery (RV-PA) shunt were developed with time-varying elastance chambers and modified Windkessel vessels. Pressure drops across the shunt and the PAB were described as non-linear functions. While mean systemic arterial pressure was maintained by adjusting stressed blood volume, diameter of the banded pulmonary arteries was increased from 1.5 to 2.0 mm at increments of 0.25 mm in the hybrid procedure model. We also varied shunt diameter of the Norwood procedure model with SPA shunt (3.0 to 4.0 mm) or RV-PA shunt (4.0 to 6.0 mm).
Results: Although mean pulmonary arterial pressure, pulmonary flow and oxygen saturation were almost equivalent among 1.75-mm PAB, 3.5-mm SPA shunt and 6.0-mm RV-PA shunt, PAB and SPA shunt delivered higher systolic and lower diastolic systemic arterial pressures because of diastolic run-off from systemic to pulmonary circulation. As a result, 1.75-mm PAB and 3.5-mm SPA shunt increased systolic pressure-volume area and impaired mechanical efficiency compared to the Norwood procedure with 6.0-mm RV-PA shunt.
Conclusions: Without the use of cardiopulmonary bypass, the hybrid procedure provided similar hemodynamics to the Norwood procedure with SPA shunt. However, this procedure had less advantage on ventricular energetics compared to the Norwood procedure with RV-PA shunt.
- © 2012 by American Heart Association, Inc.