An atrial septal defect (ASD) is a hole in the dividing wall of the left and right atrium. It is a normal development in the foetal heart that allows blood to be diverted from the lungs before birth. In the uterus, oxygen is provided to the foetus by the mother through the umbilical cord. The Foetal lungs are unable to perform this task as the baby develops in the fluid filled amniotic sac. After birth, this hole closes as the lungs expand to as they take over the role of providing oxygen to the new born baby.
Occasionally, this hole does not close promptly soon after birth. If the ASD is large, it should be closed in childhood to prevent damage to the circulation and the lungs over time. Sometimes the diagnosis is made in adulthood. If the hole is large, it should be closed. If closed promptly, the long-term outlook is excellent.
Small ASD’s do not usually cause long term problems and they do not require treatment. If an ASD is large and is not closed it causes irregular heart beats, heart failure and lung damage. Symptoms include, palpitations, shortness of breath and even strokes.
Some ASD’s can be closed by using a catheter inserted through the groin. A collapsed closure device is passed into the hole and when deployed, it opens like a balloon to close the defect. If the ASD is very large, or is in a complex position in the heart, then surgical closure using open heart surgery is required.