Discussion

This study highlights the wide variation in the assessment and management of children with a vascular ring in the UK amongst a group of experts in paediatric cardiology. Whilst there has been a large number of cases diagnosed prenatally in the UK for a few years at the time of the survey, most units had not agreed a standardised postnatal pathway for assessment and management. There is no consensus regarding which clinical features may be considered an indication of a compressive vascular ring and necessitate further investigations. Furthermore, postnatal surveillance, investigation strategy, and subsequent management of the cases is variable. In some areas, patients are solely managed by a paediatric cardiologist despite the abnormal cardiovascular anatomy not impacting upon the cardiac status. Surveillance and assessment are undertaken by professionals who understand the vasculature and surgical options, but rarely is this supported by those trained in diseases of the airway or oesophagus which are the structures affected by the vascular ring. The availability of multidisciplinary assessment for prenatally diagnosed cases may accelerate our knowledge and understanding of this new cohort of prenatally diagnosed patients. This survey has also highlighted the challenges of defining symptoms or clinical sings of a vascular ring; there was no single unifying feature which was considered definitive for tracheal or oesophageal compression. Some of these features may be intermittent, subtle, or subjective, such as stridor, wheeze, or poor feeding and some may be considered an overlap of normal such as choking when weaned onto solids and not attributed to the underlying vascular ring. However, astute history taking may reveal the compensatory mechanisms the children have developed to overcome the symptoms, for example chewing food thoroughly to aid swallowing and having been labelled as a ‘slow eater’. ^{Reference Worhunsky, Levy and Stephens6} Furthermore, the threshold for investigation varies amongst units and there is no consensus when to investigate and when to operate in the UK which reflects the opinions of international centres. ^{Reference Stephens, Eltayeb and Kennedy7–Reference Young, Hornberger and Haberer10}

Five units reported that surgery is usually performed for all cases of DAA regardless of the evolving symptoms and whilst the reason for this strategy was not sought from the respondents, there is much published data to demonstrate that DAA is frequently associated with clinical features of a vascular ring and also that there is a high proportion that are left with secondary tracheomalacia post-operatively, ^{Reference Han, Hall and Manché11} which is thought to be due to longstanding tracheal compression from the DAA. ^{Reference Worhunsky, Levy and Stephens6,Reference Han, Hall and Manché11–Reference Callahan, Merritt and Canter16} Three centres offered routine assessment of cases with a RAA and left ductal ligament in asymptomatic infants. Similarly, the rationale for this approach was not requested, but there are cases reported in the literature where there is a significant degree of tracheal compression in the absence of symptoms/clinical signs ^{Reference Vigneswaran, Kapravelou and Bell17} and also a persistence of symptoms post-operatively ^{Reference Swarnkar, Speggiorin and Austin12,Reference Depypere, Proesmans and Cools15,Reference Callahan, Merritt and Canter16,Reference Luciano, Mitchell and Fraisse18,Reference Francois, Panzer and De Groote19} which has led to the hypothesis that secondary tracheomalacia could be a result of longstanding compression causing permanent damage or distortion to the tracheal cartilage. ^{Reference Biermann, Holst and Huners20} In the modern era, vascular ring surgery is a low risk operation ^{Reference Swarnkar, Speggiorin and Austin12} and some units chose to investigate and operate early, whereas others pursue a more conservative approach and only undertake surgery when the risk of surgery is deemed to be outweighed by the clinical presentation of the child. The most beneficial approach is not known, but this study has demonstrated the variance in management of cases.

This study highlights some key objectives to plan future research studies which may benefit patients (fig 1). Whilst there is ample data describing the association of RAA with chromosomal/genetic conditions in specialist fetal medicine units, ^{Reference D’Antonio, Khalil and Zidere21} there is limited data regarding these associations in a standard population. For fetuses with DAA there is few published data, suggesting an association lower than that of RAA. ^{Reference Vigneswaran, Van Poppel and Griffiths4}

Figure 1. Graphic outlining key areas for further research at important time points following prenatal diagnosis of right or double aortic arch: prenatal, paediatric, and surgical questions.

A limitation of many prenatal series of RAA and DAA is the diagnostic accuracy for specific anatomy and this is highlighted in the results of this survey which demonstrated that less than half of fetal cardiologists were confident in their ability to identify the branching pattern of the aortic arch. If the branching pattern of the aortic arch (position of the head and neck arteries) are not sought, then this will lead to cases of a DAA with a small left arch being overlooked and misdiagnosed as a RAA. This may lead to incorrect counselling about the association of chromosomal/genetic conditions and influence prenatal decisions and postnatal management strategy.