Menu

Patent Ductus Arteriosus (PDA)

by | 20 May, 2020

Login to enrol on courses and monitor progress

Introduction

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.

Epidemiology

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

Pathophysiology

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.

Signs

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

Investigations

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

Management

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.

Complications

  • 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.

0 Comments

Submit a Comment



Your email address will not be published. Required fields are marked *

Let's Learn Together!

All our lessons and courses are free to access and use for everybody.

Join Clinician Revision to get personalised help and see your progress.

Want to contribute to a topic, lesson or quiz?