Synopsis
Classify congenital heart disease by physiology rather than colour alone, recognise duct-dependent and mixing emergencies, and organise investigation, stabilisation and specialist transfer safely across neonatal and childhood presentations.
- Acyanotic lesions usually create left-to-right shunting or obstruction without systemic desaturation; examples include ASD, VSD, PDA, aortic stenosis and coarctation before shunt reversal.
- Cyanotic lesions deliver desaturated blood to the systemic circulation through right-to-left shunting, parallel circulations or inadequate mixing; examples include tetralogy, transposition, pulmonary atresia and truncus arteriosus.
- Colour is an imperfect classifier. Acyanotic shunts can eventually become cyanotic through pulmonary vascular disease, and a critically obstructed newborn may look grey from shock rather than visibly blue.
- Initial priorities are physiology: oxygenation and ventilation, systemic perfusion, pulmonary blood flow, mixing, ductal dependency and heart failure. Name the lesion only after echocardiographic definition.
- Measure preductal and postductal saturation, brachial and femoral pulses, four-limb blood pressure when feasible, perfusion, liver size and response to carefully delivered oxygen.
- Blood gas and lactate quantify acidosis and perfusion but cannot distinguish pulmonary from cardiac disease alone. Hyperoxia response is not a substitute for echocardiography.
- Urgent paediatric echocardiography is the diagnostic reference test for anatomy, connections, shunt direction, obstruction and ventricular function.
- Suspected duct-dependent circulation requires immediate cardiac-network discussion and specialist-directed alprostadil. Prepare for apnoea, hypotension, fever and the need for ventilation during infusion and transfer.
- Do not chase a normal saturation target in a child with a known palliated or mixing circulation; use the child's documented target and assess perfusion and lactate alongside saturation.
- Long-term care is lesion-specific and may involve observation, catheter intervention, surgery, staged palliation, medicines and lifelong congenital cardiac surveillance.
Key red flags
Blue or grey tongue and mucosa, persistent low saturation or poor response to oxygen indicates central cyanosis and requires urgent hospital assessment.
Shock, weak or absent femoral pulses, metabolic acidosis, oliguria or differential upper- and lower-body perfusion suggests duct-dependent systemic obstruction.
Severe hypoxaemia with little respiratory distress, a single second sound or an abnormal cardiac silhouette raises cyanotic congenital heart disease even without a murmur.
Tachypnoea, sweating with feeds, hepatomegaly and faltering growth emerging after pulmonary resistance falls suggests a large left-to-right shunt or obstructed pulmonary venous return.
A newborn can pass pulse-oximetry screening and still have coarctation or another lesion that is not substantially hypoxaemic before ductal closure.
Sudden deeper cyanosis with irritability in tetralogy, or collapse with fever or dehydration in a child with known congenital disease, needs immediate specialist-led resuscitation.
Investigation priorities
Confirm hypoxaemia and identify differential ductal shunting patterns.
Management branches
A newborn or child has central cyanosis, shock, acidosis or severe cardiorespiratory distress.
- Provide warmth, airway and ventilation support, monitor continuously and obtain IV or IO access, glucose, gas, lactate and cultures.
- Give antibiotics promptly when sepsis is plausible and correct hypoglycaemia while arranging urgent echocardiography.
- Call neonatal, cardiac and retrieval teams early; avoid unmonitored transfer or delay for nonessential imaging.