Word of caution: early life-threatening complication linked to pulmonary flow restrictors.

A 2-month-old female (3.4 kg, 50 cm) with Down syndrome and left-to-right shunting congenital heart defects underwent an unsuccessful transcatheter ductal closure, followed by bilateral implantation of manually modified microvascular plugs (MVP-9Q) from Medtronic (Minneapolis, MN, USA), used as pulmonary flow restrictors. Post-procedure, she developed febrile respiratory distress, leading to admission to the intensive care unit. Despite initial improvement, she was readmitted with respiratory syncytial virus infection, progressing to bilateral pneumonic consolidation. Subsequent complications included pulmonary artery aneurysmal dilatation attributed to pulmonary flow restrictors, which necessitated urgent surgery two months after their implantation. The surgery involved removing the pulmonary flow restrictors and repairing the injuries to the pulmonary artery, followed by management with extracorporeal support and targeted antibiotics. The patient recovered over 12 months.