Transposition of the Great Arteries - Atrial Switch

Transposition of the great arteries (TGA) means the two main arteries leaving the heart were swapped at birth. Before the arterial switch was widely available, this was repaired with an atrial switch (the Mustard or Senning operation), which uses a baffle inside the upper chambers to redirect blood flow. Many adults today have an atrial switch repair, because it was the standard operation for several decades. Lifelong specialist follow-up is essential.

How your circulation works

In an atrial switch, a baffle or patch is placed inside the atria (upper chambers) so that oxygen-poor blood returning from the body is directed to the left ventricle → lungs, and oxygen-rich blood returning from the lungs is directed to the right ventricle, which becomes the main pump to the body.

This means the right ventricle works as your main pumping chamber for life — the right ventricle in humans does not usually do the hard work of being the main pumping chamber for the body and can sometimes weaken over time or the valve (the tricuspid valve) can leak over time.

Long-term, the main things to watch are right ventricle function, baffle problems (leaks or narrowings), and heart rhythm problems (including slow heart rate and atrial flutter).

How to stay well:

• Report palpitations or fainting promptly — people with an atrial switch are at higher risk of heart rhythm problems, which can usually be treated.

• Keep active at a level that suits you. Ask your heart team what is safe.

• Take your medicines as prescribed — some people take blood thinners or medicines to help the heart or heart rhythm.

• Avoid smoking and vaping, and drink alcohol in moderation.

• Pregnancy and procedures: pregnancy puts extra strain on the right ventricle, so plan it carefully with your ACHD team beforehand.

Contact your heart team when you notice any of these:

• Swelling of your tummy, ankles, feet or face

• New or worse breathlessness, or feeling unusually tired

• Chest pain, a racing or very irregular heartbeat, or fainting / near-fainting

• A painful, swollen or warm leg

• Fever or signs of infection without an obvious cause

• Feeling light-headed or dizzy, losing your appetite, or feeling very weak

Emergency — get help immediately if:

If you get sudden chest pain, collapse, or major trouble breathing, call emergency services immediately and tell them you have had an atrial switch (Mustard or Senning) operation for transposition of the great arteries.

Your regular check-ups

An atrial switch needs lifelong specialist follow-up with an ACHD team. At your check-ups you will usually have a heart scan (echocardiogram), and often MRI to measure right ventricle function precisely, plus ECG, Holter monitoring and exercise tests. Because heart rhythm problems are common, your team will keep a close eye on your heart rate and rhythm and may discuss a pacemaker if your heart rate is too slow, or treatment for flutter.

Questions for your doctor

You may find it helpful to ask your heart team these questions:

1. How well is my right ventricle working, and how is that monitored?

2. What should I do if I feel palpitations or faint?

3. Is pregnancy something I should plan, and how?

4. What level of exercise is safe for me?

ⓘ This leaflet provides general information only and is not medical advice. Always follow the advice of your cardiology team.