The aortic arch in tetralogy of Fallot: types of branching and clinical implications

Introduction: Tetralogy of Fallot is the most common form of cyanotic CHD, with an incidence of 421 cases per million live births, constituting around 10% of CHD. Variations in aortic arch anatomy associated with tetralogy of Fallot, other than the incidence of right aortic arch (13-34%), are not frequently reported. A comprehensive analysis of a large number of tetralogy of Fallot cases is required to arrive at a compendious description of aortic arch anatomy. Materials and methods: All patients with a diagnosis of tetralogy of Fallot who had CT or MRI either pre or post procedures between 1 January 2010 and 31 December 2019 at our hospital were included in the study. Using radiology consultants' reports and analysis of individual images, we identified the various morphological patterns of aortic arches prevalent in these patients. Result: Out of 2684 patients who met the inclusion criteria, 1983 patients had left aortic arch (73.9%), 688 patients had right aortic arch (25.7%), four patients had cervical aortic arch (0.15%), eight patients had double aortic arch (0.3%), one patient had an aorto-pulmonary window (0.04%), and none of the patients had interrupted aortic arch. Sub-classification and clinical implications of the arch variations are described. Conclusion: Up to 10% of tetralogy of Fallot patients may have significant anatomical variations of aortic arch that would necessitate changes or additional steps in their surgical or interventional procedures.