Duct-dependent congenital heart disease: recognition and stabilisation

The organising principle is simple: the ductus arteriosus is a bridge, and duct-dependent lesions are the ones where that bridge is the only road. In fetal life the placenta oxygenates the blood and the ductus arteriosus shunts most of the right ventricular output away from the lungs. After birth the lungs take over, oxygen tension rises, and the duct closes functionally within hours and anatomically over days. If the lesion blocks the pulmonary outflow, closing the duct cuts the only route blood had to reach the lungs, and the baby turns blue. If the lesion blocks the systemic outflow, closing the duct cuts the only route to the body, and the baby goes into shock. ^[3]

This page covers the recognition and emergency stabilisation of duct-dependent congenital heart disease in neonates and infants. It works through the two-pathway split — duct-dependent pulmonary versus duct-dependent systemic circulation — the physiology of why a well baby collapses at day three, the pulse oximetry screening programme and the hyperoxia test, the emergency prostaglandin E1 protocol with its apnoea and hypotension traps, the parallel sepsis workup, and the retrieval pathway to a cardiac surgical centre. It links to the murmur assessment, shock, and neonatal sepsis topics rather than repeating their full detail. ^[4]

Overview & Definition

A baby born with a severe obstruction on one side of the heart can survive in fetal life because the ductus arteriosus lets blood detour around the block. The condition earns its name — duct-dependent — because that detour is not a luxury but a lifeline. The moment the duct closes, the child loses the only route for either pulmonary or systemic blood flow, and the clinical picture is either deep cyanosis or cardiovascular collapse. ^[3]

Duct-dependent pulmonary circulation covers the right-sided obstructions where blood cannot reach the lungs once the duct closes: pulmonary atresia, critical pulmonary stenosis, severe tetralogy of Fallot, tricuspid atresia, and severe Ebstein anomaly. Before the duct closes, blood flows from the aorta through the ductus into the pulmonary artery and reaches the lungs in reverse. When the duct shuts, pulmonary blood flow plummets and the baby becomes deeply cyanotic. ^[3]

Duct-dependent systemic circulation covers the left-sided obstructions where blood cannot reach the body once the duct closes: hypoplastic left heart syndrome, critical coarctation of the aorta, interrupted aortic arch, critical aortic stenosis, and mitral atresia. Before the duct closes, the right ventricle pumps blood through the ductus into the aorta and perfuses the body. When the duct shuts, systemic output collapses and the baby presents in shock with weak pulses and metabolic acidosis. ^[3]

References11ShowHide

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