It is the most common congenital abnormality, which occurs once in about every four thousand births. It is about two to three times more common in females. The patent ductus arteriosus is foetal pathway connecting pulmonary artery at its bifurcation to the aorta just beyond the origin of the left subclavian artery. Through this channel blood by passes the collapsed lungs in embryonic life so that blood flows directly from the pulmonary artery into the aorta by passing the lungs.

With the birth, the baby starts respiration with expansion of the lungs. The blood in the pulmonary artery passes to the lungs, so the ductus arteriosus usually closes within a few days and becomes fibrotic, which is then called ligamentum arteriosum. It is said that changes in the oxygen tension of the arterial blood exerts a direct stimulus on the closure of the ductus. It is not known, why patency exists in a few babies, but it has been shown that an infusion of prostaglandin may maintain patency of ductus.

There is left ventricular hypertrophy. Many cases may remain asymptomatic, whereas a few with large patent ductus may cause serious heart failure during the first year. Congestive heart failure is usually seen only in adult patients. It often appears during the first pregnancy in females. There is continuous murmur. With smaller patent ductus, this murmur becomes audible earlier much before the patient develops cardiac failure. A wide pulse pressure is found with a large ductus. A thrusting left ventricular apical impulse may be felt.

Tests done to diagnose patent ductus arteriosus are-

1.   Chest X-ray.

2.   Electrocardiogram.

3.   Cardiac catheterization.

4.   Aortography.

Treatment-

Surgery is the treatment of choice. This is usually carried out in babies over two to three years of age. The operative risk is low and the results are excellent.