Systemic venous collaterals and congenital portosystemic shunt: Overlooked causes of Glenn shunt failure-A case report.

Glenn shunt dysfunction in single‑ventricle palliation is multifactorial. Although aorto‑pulmonary collaterals are usually considered, systemic veno‑venous collaterals and congenital portosystemic shunts (CPSS) may be underrecognized causes (1,7). Our patient, a 30‑month‑old child with mitral valve atresia, severe hypoplastic left ventricle, large ventricular septal defect (VSD), pulmonary valve atresia, and ductus arteriosus-dependent pulmonary blood flow, who was undergone some palliation stages including patent ductus arteriosus (PDA) stenting / modified Blalock-Taussig (BT) shunt and a right‑sided bidirectional cavopulmonary anastomosis (Glenn). Despite an initially acceptable course, the child developed progressive central cyanosis.