Introduction
The hybrid procedure (HP, bilateral pulmonary artery bands and stenting of the arterial duct) for hypoplastic left heart syndrome (HLHS) and its variants was proposed in the early 1990s(1) as an alternative palliation to the Norwood procedure, particularly to avoid cardiopulmonary bypass in high-risk infants. Atrial septectomy forms part of the standard Norwood procedure, whereas during the hybrid procedure any atrial intervention will usually be performed off bypass. There is varying opinion on the optimal timing of atrial intervention in patients with HLHS undergoing HP from at the time of the procedure to performing later if signs of atrial restriction(2-4). Decisions about whether or not to intervene on the atrial septum are generally based on echocardiographic assessment including mean gradient across the atrial septum, left atrial size and pulmonary vein Doppler interrogation (5). These parameters may be abnormal in HLHS (6) and are impacted by high pulmonary blood flow after initial palliation. Such assessment is clinically important to optimise free flow of oxygenated blood from the left atrium to the systemic arterial circulation and to avoid severe left atrial hypertension with potentially deleterious effects on development of the pulmonary vasculature.
Fenstermaker at el(5) described changes in the pulmonary artery band Doppler over time following HP. That study described alterations in the shape of the Doppler trace in a small subset of patients who required atrial septal intervention. In this retrospective study, we review the characteristic of the branch pulmonary artery band Doppler values in patients with HLHS after the hybrid procedure, who have required atrial septal intervention prior to their second palliation. We hypothesized that the previously seen changes in pulmonary artery band Dopplers would aid in identifying patients who require atrial septal intervention. Patients were divided into two groups (critical aortic stenosis and classical HLHS) to further investigate the potential impact of residual forward flow through the left heart.