Characterisation of computed tomography angiography findings in paediatric patients with heterotaxy

Heterotaxy refers to the abnormal arrangement of organs across the left–right axis and is typically associated with complex cardiovascular malformations. To characterise the range of cardiac and extracardiac CT angiography findings in children with heterotaxy using the latest nomenclature consensus and to compare the different types of isomerism. We retrospectively analysed the data of 64 consecutive paediatric patients referred to our tertiary paediatric cardiovascular centre who underwent CT angiography for the evaluation of known or suspected heterotaxy within a 52-month period. Right atrial isomerism was identified in 44 (69%) children, while left atrial isomerism was identified in 18 (28%) children. Atrial appendage anatomy and situs could not be determined in 2 children (3%). Associated heart defects included complete atrioventricular canal (CAVC) in 51 (80%) children, total anomalous pulmonary venous return in 43 (67%) and pulmonary atresia in 23 (36%). The bronchial branching pattern corresponded to atrial appendage morphology in all children except in the two in whom atrial appendage morphology could not be defined. In children with right atrial isomerism, the most common associated abnormalities were CAVC (n=41, 93%) and asplenia (n=34, 77%), while in those with left atrial isomerism, the most common associated abnormalities were polysplenia (n=17, 94%) and an interrupted inferior vena cava with azygos continuation (n=15, 83%). CT angiography provides useful cardiovascular and extracardiac data on heterotaxy, which frequently involves a pattern of side-related findings but has great anatomical variability.