Persistent ductus arteriosus (PDA)

The ductus arteriosus of Botallo acts during the embryo period as a short circuit between the pulmonary artery and descending aorta in order to direct the blood past the non-functioning lungs. The lung expands with the first breaths. The pulmonary vascular resistance falls as a result. For a short time after birth, there is a left-to-right shunt but this is soon reduced as a result of active contraction of muscle fibres in the ductus arteriosus. This produces functional closure of the ductus. In the following weeks, the ductus arteriosus is converted to connective tissue cord, which persists throughout life as the ligamen­tum arteriosum of Botallo.

If these processes do not take place, the condition is called persistent ductus arteriosus. Since life expectancy is reduced in the majority of patients due to endocarditis and development of pulmonary hypertension, every patent ductus should be operated during childhood. The majority of cases of patent ductus can be closed by drug therapy with indomethacin. Moreover, the majority can also be closed interventionally using coils or umbrella occlusion. The number of operative procedures has therefore diminished greatly.

Surgical closure is usually indicated only in immature premature infants weighing less than 1000 g, in whom drug-induced closure is often unsuccessful and where their small physical size makes intervention impossible.

The operation is performed through a left-sided posterolateral thoracotomy in the fourth or fifth inter­costal space. After exposing the aortic arch, subclavian artery and descending aorta, the ductus arteriosus can be identified easily. It is closed by double ligature, application of clips or by dividing it.