In Vitro Assessment of the Assisted Bidirectional Glenn Procedure for Stage One Single Ventricle Repair

This in vitro study compares the hemodynamic performance of the Norwood and the Glenn circulations to assess the performance of a novel assisted bidirectional Glenn (ABG) procedure for stage one single ventricle surgery. In the ABG, the flow in a bidirectional Glenn procedure is assisted by injection of a high-energy flow stream from the systemic circulation using an aorta-caval shunt with nozzle. The aim is to explore experimentally the potential of the ABG as a surgical alternative to current surgical practice. The experiments are directly compared against previously published numerical simulations. A multiscale mock circulatory system was used to measure the hemodynamic performance of the three circulations. For each circulation, the system was tested using both low and high values of pulmonary vascular resistance. Resulting parameters measured were: pressure and flow rate at left/right pulmonary artery and superior vena cava (SVC). Systemic oxygen delivery (OD) was calculated. A parametric study of the ratio of ABG nozzle to shunt diameter was done. We report time-based comparisons with numerical simulations for the three surgical variants tested. The ABG circulation demonstrated an increase of 30-38% in pulmonary flow with a 2-3.7 mmHg increase in SVC pressure compared to the Glenn and a 4-14% higher systemic OD than either theNorwood or the Glenn. The nozzle/shunt diameter ratio affected the local hemodynamics. These experimental results agreed with those of the numerical model: mean flow values were not significantly different (p > 0.05) while mean pressures were comparable within 1.2 mmHg. The results verify the approaches providing two tools to study this complicated circulation. Using a realistic experimental model we demonstrate the performance of a novel surgical procedure with potential to improve patient hemodynamics in early palliation of the univentricular circulation.