24. Congenital heart diseases and their treatment; persistent ductus arteriosus treatment

Congenital heart diseases: persistent ductus arteriosus and treatment

The ductus arteriosus connects the pulmonary artery to the descending aorta in fetal life, diverting blood away from the fluid-filled lungs.
After birth, increased oxygen tension and reduced prostaglandin E2 normally cause functional closure, followed by anatomical closure. Persistent patency produces a left-to-right shunt when pulmonary vascular resistance falls.
Patent ductus arteriosus (PDA) may be isolated or associated with prematurity, congenital rubella or other congenital cardiac lesions.

Blood flows from the aorta to the pulmonary artery, increasing pulmonary blood flow and returning excess volume to the left atrium and ventricle.
A significant PDA can cause left-sided volume overload, pulmonary overcirculation, heart failure and eventually pulmonary vascular disease with shunt reversal (Eisenmenger physiology).
Small PDA may be asymptomatic. Larger PDA may cause tachypnoea, feeding difficulty, poor weight gain, recurrent respiratory infections and heart failure in infants.
Classic examination finding is a continuous 'machinery' murmur near the left upper sternal border/infraclavicular area, with bounding pulses and wide pulse pressure in a significant shunt.

Echocardiography with Doppler confirms PDA, assesses duct size and flow, chamber enlargement, pulmonary pressures and associated congenital defects.
ECG may show left atrial/ventricular enlargement in significant shunts. Chest radiograph may show cardiomegaly and pulmonary plethora.
Assess oxygen saturation and signs of pulmonary hypertension. Cardiac catheterisation is reserved for selected haemodynamic assessment or intervention planning.

Management depends on age, size, haemodynamic significance, symptoms and pulmonary vascular resistance.
In preterm infants, pharmacological closure may be attempted with ibuprofen or indomethacin; paracetamol is used in selected settings. Contraindications and renal, gastrointestinal and platelet effects must be considered.
Transcatheter device closure is preferred for many suitable children and adults. Surgical ligation is used when catheter closure is unsuitable or unsuccessful, or in selected premature infants.
Do not close a PDA in established irreversible pulmonary vascular disease with right-to-left shunting; closure may worsen right-heart failure.
Monitor for residual shunt, device embolisation, obstruction of adjacent vessels, haemolysis, endarteritis and ventricular function. Endocarditis prevention advice follows current guidelines.