Atrial Septal Defect (ASD)
What is It?
An atrial septal defect (ASD), often referred to as a ‘hole in the heart’, is an opening in the wall (septum) between the two upper chambers of the heart that allows oxygenated and deoxygenated blood to mix. This creates a shunt, and the severity of symptoms depends on the size of the defect. A patent foramen ovale (PFO) is a related condition where a hole in the heart that should close after birth remains open. PFOs are common and often asymptomatic. ASD is one of the most common congenital heart defects.
What are the symptoms?
Many patients with small ASDs or PFOs have no symptoms, and the defect may be found incidentally. Symptoms, when present, may include palpitations, shortness of breath on exertion, fatigue, leg swelling, frequent respiratory infections, migraines, or a history of stroke. Large, untreated ASDs can lead to right heart enlargement and pulmonary hypertension.
What are the causes?
At One Heart Centre our cardiologists screen for all causes of atrial septal defect. ASDs are congenital, meaning they are present from birth. Contributing factors include:
- Genetic factors, including chromosomal abnormalities such as Down syndrome.
- Family history of congenital heart disease.
- Maternal factors during pregnancy, including rubella infection, diabetes, smoking, alcohol use, and certain medications.
- In most cases, ASDs occur sporadically without an identifiable cause.
How is it investigated?
The initial investigation for ASD is a bubble echocardiogram study to visualise whether microbubbles injected into the blood pass through the defect. A transoesophageal echocardiogram (TOE) may also be used to accurately assess the hole. Cardiac CT and/or MRI may be considered to visualise the pulmonary venous anatomy. An ECG and chest X-ray help assess right heart strain.
What are the treatments?
At One Heart Centre our cardiologists have post-fellowship training in managing atrial septal defects and will provide a personalised treatment plan for your ASD. Treatment options include:
- Monitoring: Small ASDs and asymptomatic PFOs may simply be observed.
- Medications: Beta-blockers, blood thinners, or diuretics may be used to manage symptoms and reduce complications.
- Percutaneous closure: A catheter-based procedure using a device delivered through a blood vessel to close the defect, suitable for most secundum ASDs.
- Open-heart surgery: Required for primum, sinus venosus, or very large defects, using a patch to close the hole.