Introduction
The ductus arteriosus (DA) is an opening between two of the major blood vessels of the heart. When your baby is still inside the womb, the placenta does the work of exchanging oxygen (O2) and carbon dioxide (CO2) through the mother's circulation. The baby’s lungs are not used for breathing.
The ductus arteriosus is a blood vessel that joins two of the major arteries (the aorta and the pulmonary artery) that are connected to the heart in the unborn foetus. It allows most of the blood from the heart to bypass the lungs, as a foetus does not need its lungs for breathing.
Once a baby is born and the lungs fill with air, the ductus arteriosus normally closes within a few days. In some babies (especially premature infants), however, the ductus arteriosus remains open (patent) which can lead to problems of fluid overload in the heart and lungs. This is known as Patent (or Persistent) Ductus Arteriosus (PDA).
Patent ductus arteriosus is a common problem in premature infants. Up to 60% of infants born at less than 28 weeks' gestation, have a patent ductus arteriosus.
Signs and symptoms
Some babies with a patent ductus arteriosus develop signs of overfilling of the lungs ("wet lungs") due to shunting across the patent ductus arteriosus and recycling of the blood through the lungs.
These signs may include:
- fast breathing
- working hard to breathe
- or the need for increased breathing support.
A heart murmur may be the only sign that a baby has patent ductus arteriosus. A heart murmur is an extra or unusual sound heard during the heartbeat.
Sometimes babies will develop low blood pressure (hypotension).
Diagnosis
Patent ductus arteriosus is diagnosed by Doppler echocardiography (echo). An echo is a painless test that uses sound waves to create a moving picture of your baby's heart. This is very similar to the ultrasound scans done on the mother during pregnancy.
Treatment
The goal of treatment is to help close the patent ductus arteriosus and to support your baby with treatments that counteract the effects of it (careful fluid management, CPAP, diuretcis) until closure occurs. The decision to treat the patent ductus arteriosus depends on the size of the duct and the clinical condition of your baby. Small ducts may not need treatment and usually close without specific medical treatment.
In premature babies, an anti-inflammatory drug called ibuprofen may be used. Ibuprofen has been shown to be effective in closing the patent ductus arteriosus. Sometimes a few courses of the medication may be needed if the patent ductus arteriosus fails to close or re-opens again.
If it does not respond to medication, or is due to causes other than prematurity, surgery may be needed. This surgery is called ligation and involves placing a suture or clip around the ductus to close it.
Management
Prognosis and long term outcome
Most babies tolerate the patent ductus arteriosus and its treatments well. The long term outcome is more dependent on the age and birth weight of your baby. The need for surgery does have impact on the long term neuro- developmental outcome of preterm babies. There is no significant inheritance pattern for patent ductus arteriosus.