Duct-dependent congenital heart disease: Case

This baby has hypoplastic left heart syndrome, the most severe of the duct-dependent systemic lesions. The left side of the heart is underdeveloped, and the right ventricle must pump blood both to the lungs through the pulmonary artery and to the body through the ductus arteriosus into the aorta. When the duct closes at day two to five the baby loses systemic blood flow and collapses in shock, which is exactly the presentation here. The history of a well baby at discharge, the collapse on day 3, the weak femoral pulses, the severe metabolic acidosis, and the cardiomegaly on chest X-ray together make the diagnosis before the echocardiogram confirms it. [1]

Clinical findings

The key findings in this case are the day-3 collapse in a previously well neonate, the signs of severe cardiogenic shock, and the echocardiographic confirmation of hypoplastic left heart syndrome. The baby was well on day 1 because the ductus arteriosus was still open and the right ventricle was perfusing the entire body through it. The progressive deterioration over 12 hours reflects the gradual anatomical closure of the duct as it loses its lumen and systemic blood flow falls. [1]

The physical signs are the signature of a left-sided duct-dependent lesion in collapse. The pallor and mottling with prolonged capillary refill reflect poor peripheral perfusion. The tachycardia and tachypnoea with grunting are the compensatory responses to shock and metabolic acidosis. The weak femoral pulses occur because the duct was the source of lower-body blood flow and it has closed. The hyperdynamic precordium reflects the single working ventricle doing the work of both. The severe metabolic acidosis with a base excess of minus 15 and a lactate of 9 is direct evidence of tissue hypoperfusion from loss of systemic cardiac output. [1]

The echocardiogram confirms the anatomy: a small or absent left ventricle, a hypoplastic aortic and mitral valve, and a diminutive ascending aorta. The ductus arteriosus is restrictive, which explains the collapse. The right ventricle is the dominant pumping chamber, and blood flows from the pulmonary artery through the duct into the descending aorta in a retrograde fashion to supply the head and neck vessels and the lower body. [3]

Management

The immediate management is to start prostaglandin E1 (alprostadil) at 0.01 to 0.05 micrograms per kilogram per minute intravenously to reopen the ductus arteriosus and restore systemic blood flow. This should have been started on clinical suspicion before the echocardiogram was available, because the drug is life-saving and the echo confirms rather than initiates treatment. The infusion works within minutes to hours, and the team should see improvement in the perfusion, the acidosis, and the pulses as the duct reopens. [2]

Anticipate the side effects of prostaglandin E1. Apnoea occurs in approximately 10 percent of treated neonates and is the reason many units electively intubate before transfer. Hypotension and fever are vasodilatory effects that usually respond to dose reduction. The pyrexia can mask a genuine fever from sepsis, so blood and CSF cultures should be sent and empiric antibiotics started in parallel. Correct the hypoglycaemia, address the metabolic acidosis by restoring perfusion rather than giving bicarbonate, and arrange transfer to a cardiac surgical centre with a dedicated neonatal transport team. The prostaglandin infusion continues from the moment it is started until the first stage of surgery. [2]

Definitive management is staged single-ventricle palliation. The Norwood procedure is performed in the first weeks of life and creates a new aorta from the pulmonary artery, establishes a stable source of pulmonary blood flow via a shunt, and allows the right ventricle to pump blood to the body. The bidirectional Glenn procedure at around 4 to 6 months of age connects the superior vena cava directly to the pulmonary arteries, and the Fontan completion at 2 to 3 years directs inferior vena cava blood to the lungs as well, completing the single-ventricle circulation where the right ventricle pumps to the body and passive venous flow supplies the lungs. [3]

Complications and follow-up

The complications of hypoplastic left heart syndrome and its staged palliation are substantial. The Norwood procedure carries a significant operative mortality, and the inter-stage period between the Norwood and the Glenn is the highest-risk phase, when a small shunt obstruction can be fatal. Families are taught home monitoring of saturations and feeding, and some programmes use an inter-stage shunt surveillance strategy. [3]

Neurodevelopmental outcome is a concern for all survivors of critical congenital heart disease. The combination of preoperative shock, cardiopulmonary bypass, and deep hypothermic circulatory arrest means that a proportion of children have cognitive, motor, and behavioural challenges that emerge over the school years. Structured neurodevelopmental follow-up, early intervention services, and educational support are part of the standard of care. The family needs a named cardiologist, a primary-care partner who understands the anatomy, a MedicAlert, and a structured transition to adult congenital cardiology in adolescence. [1]