Atrial Septal Defect

An Atrial Septal Defect (ASD) is a type of congenital heart defect—meaning it’s present at birth—where there is an abnormal opening in the wall (called the atrial septum) that separates the two upper chambers of the heart (the right and left atria).

🫀 What Happens in ASD?

Normally, oxygen-rich blood flows from the lungs into the left atrium, and then gets pumped to the body. In ASD, some of that blood flows from the left atrium to the right atrium through the opening. This is called a left-to-right shunt.

As a result:

• Extra blood flows into the right side of the heart and then into the lungs.
• Over time, this can cause enlargement of the right atrium and ventricle, and increased pressure in the lungs (pulmonary hypertension).

🩺 Symptoms

Small ASDs might cause no symptoms and can close on their own in early childhood. Larger ASDs may cause:

• Shortness of breath (especially with exertion)
• Fatigue
• Heart palpitations or skipped beats
• Frequent respiratory infections in children
• Swelling in legs, feet, or abdomen (in severe cases)

🧪 Diagnosis

• Echocardiogram (Echo) – primary tool to visualize the defect
• Transesophageal Echocardiogram for more accurate assessment of the defect
• ECG, chest X-ray, or MRI may also be used
• Sometimes discovered incidentally in adults

🛠️ Treatment

Depends on size and symptoms:

• Observation – small ASDs may close on their own
• Medications – not to fix the defect but to manage symptoms (like diuretics or antiarrhythmics)
• Catheter-based closure – a device is placed via a catheter to seal the hole (minimally invasive)
• Surgical repair – in cases where the catheter-based method isn't suitable

⚠️ Complications if Untreated

• Right-sided heart failure
• Arrhythmias (especially atrial fibrillation)
• Stroke (due to paradoxical embolism if blood clots bypass the lungs)
• Pulmonary hypertension