Discussion

The coexistence of truncus arteriosus and tricuspid atresia is a rare and complex anomaly, first reported in 1974. ^{Reference Tandon, Moller and Edwards2} Since then, only isolated case reports and a limited number of small case series have been published. In addition to tricuspid atresia, other forms of functionally univentricular hearts reported in association with truncus arteriosus include unbalanced atrioventricular septal defect, double-inlet left ventricle, and hypoplastic left heart syndrome. ^{Reference Chatila, Houyel, Hily and Bonnet3,Reference Elhedai, Yong and Chaudhari4} Recent reports have demonstrated that although staged single-ventricle palliation may be feasible in selected patients, overall outcomes remain poor because of the complexity of the cardiac anatomy and the frequent presence of associated cardiac and extracardiac anomalies. ^{Reference Elhedai, Yong and Chaudhari4,Reference Weld, Lee and Loomba5}

In truncus arteriosus, increased pulmonary blood flow frequently leads to early pulmonary hypertension and heart failure in the neonatal period, necessitating timely surgical intervention. A 22q11.2 deletion is present in approximately 35.5% of patients. ^{Reference Peyvandi, Lupo and Garbarini6} In our patient, no 22q11.2 deletion was identified, and chromosomal analysis demonstrated a normal karyotype, despite the presence of multiple extracardiac anomalies.

The current surgical strategy for patients with truncus arteriosus and single-ventricle physiology is staged palliation aimed at achieving Fontan circulation. Initial palliation may include pulmonary artery banding or separation of the pulmonary arteries from the truncal vessel followed by establishment of controlled pulmonary blood flow using a systemic-to-pulmonary artery shunt. ^{Reference Kobayashi, Sano and Narumiya7} Subsequent bidirectional cavopulmonary anastomosis and Fontan completion are performed when anatomical and haemodynamic conditions permit. In cases with associated interrupted aortic arch or coarctation, simultaneous repair or hybrid procedures may be necessary. Weld et al. successfully performed a hybrid procedure involving ductal stenting and pulmonary banding in a premature infant with truncus arteriosus, tricuspid atresia, and interrupted aortic arch. ^{Reference Weld, Lee and Loomba5}

To our knowledge, this is the lowest birth weight infant reported with this rare combination. Despite planned staged palliation, the outcome was unfavourable because of extreme prematurity, neonatal sepsis, and associated comorbidities. Our case further highlights the considerable challenges in managing this exceptionally rare anomaly in very low birth weight infants.