Patent Ductus Arteriosus (PDA)

by | 20 May, 2020

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A patent ductus arteriosus (PDA) is a common congenital lesion. The ductus arteriosus is a normal vascular channel present during intrauterine life that connects the pulmonary artery and the descending aorta. Normally, it closes within 48 hours of birth. Persistence of this channel provides a continuous aorta-to-pulmonary shunt.


PDA is the second commonest congenital heart defect after ventricular septal defects. It accounts for 12% of congenital heart defects.

Risk factors

  • Female
  • Prematurity
  • Other congenital cardiac lesions e.g. coarctation of aorta, VSD
  • Congenital rubella syndrome


The ductus arteriosus is a channel connecting the aorta to the pulmonary artery present in intrauterine life. Normally, it closes within a few days of birth but can pathologically fail to close.

Foetal life (Physiological)

The ductus arteriosus diverts blood away from the unexpanded, high-resistance pulmonary circulation into the systemic circulation, where it can be oxygenated via the placenta.

Adult life with PDA (Pathological)

There is a persistent aortic-to-pulmonary artery shunting. This increases preload to the left ventricle via increased recirculation. If the shunt is large, this can produce left ventricular heart failure and pulmonary hypertension. In summary: Aorta-to-pulmonary shunting → ↑ Pulmonary venous return → ↑ Left ventricular preload

Clinical features

Usually asymptomatic until later in life when complications, such as heart failure or infective endocarditis, may develop. If it is a large shunt, there may be a failure to thrive.


  • Continuous machinery murmur – present in systole and diastole. Loudest in pulmonary region and usually associated with a thrill
  • Bounding pulse


  • Chest x-ray: Enlarged aorta, prominent pulmonary vasculature
  • ECG: left ventricular hypertrophy
  • Echocardiography: confirms patent ductus


Ligate the ductus arteriosus surgically or angiographically. This should be performed as soon as possible, preferably before the age of 5.

Premature babies

Premature babies commonly have a patent ductus arteriosus. This can be treated medically with indomethacin (prostaglandin inhibitor) or ibuprofen to stimulate ductus closure. Repair surgically if it persists beyond 6 months of age.


  • Infective endocarditis
  • Heart failure
  • Eisenmenger’s syndrome

Eisenmenger’s syndrome

With time, pulmonary hypertension may develop as a result of damage to the pulmonary vasculature because of higher pressures. Pulmonary hypertension can reverse flow through the duct, creating a pulmonary-to-aorta shunt. Clinical features include right ventricular hypertrophy, cyanosis and clubbing.


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