Objective: There has been a rise in the prenatal detection of right sided aortic arch (RAA). When associated with a left-sided arterial duct (LD), this forms a vascular ring encircling the trachea. Infants may have symptoms or signs suggestive of trache-oesophageal compression but many are asymptomatic. The objective of this study was to investigate the relationship between symptoms and severity of tracheo-bronchial compression assessed by bronchoscopy. Methods: Retrospective review of all cases of prenatally diagnosed RAA-LD in the absence of associated congenital heart disease at Evelina London Children’s Hospital and Kings College Hospital over a 4-year period between April 2015-2019. Clinical records, fetal echocardiograms and free-breathing flexible bronchoscopy (FB) data were reviewed. Results: 112 cases of isolated RAA-LD were identified of whom 82 cases (73%) underwent FB. FB was performed median age of 11 months (range 1-36 months), no complications occurred. Aberrant left subclavian artery (ALSA) was present in 86% (96/112) and mirror image branching (MIB) in 13% (15/112). 34/112 (30%) reported symptoms during follow up. 36/77 (47%) with ALSA who underwent FB showed moderate-severe compression mostly at distal tracheal and carinal level of whom 38% had parent-reported symptoms. Moderate-severe compression was seen in 3/5 (60%) with MIB mostly at mid tracheal level of whom 3 were symptomatic but only 2 with compression. In total 36% (18/50) of investigated asymptomatic patients showed moderate to severe compression. Respiratory symptoms were poorly predictive of moderate-severe compression (positive predictive value 66%). Conclusion: The absence of symptoms did not exclude significant tracheal compression. The anatomical effect of the vascular ring is underappreciated when symptoms alone are used as a marker of tracheal compression.

Introduction: The hybrid procedure (HP) - bilateral pulmonary artery bands+ductal stent - is an alternative palliation for high-risk hypoplastic left heart syndrome (HLHS) patients. Assessment and management of atrial restriction here is debated and we sought to identify useful echocardiographic parameters. Methods: Patients undergoing HP for HLHS were identified. Echocardiograms at birth, immediately after HP and pre-and post-atrial intervention were reviewed as well as time-matched echocardiograms in HP patients not requiring atrial intervention. Atrial septal parameters and systolic (Svel), diastolic (Dvel) and mean velocities were recorded on both bands and systolic to diastolic velocity ratio (Svel:Dvel), pulsatility index (PI) and velocity time integral (VTI) calculated. Results: Fifteen HP were compared to 5 controls. Age effect was not significant. There was a significant rise in peak Svel and changes in Dvel, Svel:Dvel and PI over time (<0.05). Although the pattern of change similar, the fall in Dvel and rise in Svel:Dvel and PI was more significant on the left. Compared to controls, transatrial gradient and VTI were significantly increased initially post-hybrid (median 0.4m/s vs 0.7m/s p=0.04; 29.1cm vs 64.6cm p=0.018) but not significantly different prior to septostomy when the only significant differences were seen with all left band parameters. Conclusions: After HP the transatrial gradient alone cannot be used. Significant changes in band Doppler parameters were not apparent in the control group but were principally seen in the left band with reduction in Dvel and increase in Svel:Dvel and PI in those undergoing an atrial intervention.