IntroductionA 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.
EpidemiologyPDA is the second commonest congenital heart defect after ventricular septal defects. It accounts for 12% of congenital heart defects.
- Other congenital cardiac lesions e.g. coarctation of aorta, VSD
- Congenital rubella syndrome
PathophysiologyThe 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 featuresUsually 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
ManagementLigate the ductus arteriosus surgically or angiographically. This should be performed as soon as possible, preferably before the age of 5.
Premature babiesPremature 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