Impact on the trachea in children with prenatally diagnosed vascular ring formed by a right aortic arch.

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 tracheoesophageal compression but many are asymptomatic. The objective of this study was to investigate the relationship between symptoms and severity of tracheobronchial 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: One hundred and twelve 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; 3 were symptomatic but only 2 had tracheal compression. In total 36% (18/50) of investigated asymptomatic patients showed moderate-severe compression. Respiratory symptoms were poorly predictive of moderate-severe tracheal compression (positive predictive value 66%, negative predictive value 64%). CONCLUSION: The absence of symptoms did not exclude significant tracheal compression. The anatomical effect of the vascular ring is under appreciated when symptoms alone are used as a marker of tracheal compression.

Genetic testing in children with surfactant dysfunction.

OBJECTIVES: To present the UK experience in genetic diagnoses of surfactant protein dysfunction disorders and develop a referral algorithm for neonates and children with persistent respiratory problems. MATERIALS AND METHODS: Between 2006 and 2011, 427 cases were referred for surfactant mutation analyses to the North East Thames Regional Molecular Genetics Laboratory at Great Ormond Street Hospital, London. The results were reviewed and referring physicians of mutation positive cases contacted to complete a questionnaire providing clinical, radiological, histological and outcome information. RESULTS: 25 new cases were found to have genetic mutations for surfactant dysfunction disorders (7.5%), with six resulting in surfactant protein B dysfunction, seven surfactant protein C dysfunction and 12 ATP-binding cassette subfamily A member 3 (ABCA3) dysfunction. The referrals were from 15 different paediatric centres. In addition, three affected surfactant protein B (SFTPB) cases were prenatal diagnoses, following the birth of previously affected children. The majority of the confirmed cases (23 of 25) were born after 37 weeks gestation. All children with SFTPB dysfunction and the majority of ABCA3 patients presented with respiratory distress at birth. All SFTPB cases died from intractable respiratory failure. The outcome for ABCA3 mutations was variable with seven survivors. The clinical and radiological presentation of surfactant protein C (SFTPC) patients suggested mainly interstitial lung process with the majority surviving on medication. CONCLUSIONS: Surfactant mutation analysis is now well established in the UK and allows better genetic diagnosis and counselling. The rarity of the condition makes it difficult to develop a validated algorithm for genetic evaluation with a need for international networking. Referrals need to be rationalised for the service to be time and cost effective.