This information is for patients having an ultrasound (scan) of the heart from the oesophagus (the gullet), known as a transoesophageal echocardiogram (TOE).

What is a transoesophageal echocardiogram (TOE)?

A transoesophageal echocardiogram (TOE) uses sound waves (ultrasound) from a probe to check the structure of your heart and how well it is functioning. 

The probe is about as wide as an index finger and goes in the mouth, down the throat and into the oesophagus. The probe produces clearer and more accurate echo pictures than those taken from the front of the chest. 

This is because the oesophagus lies immediately behind the heart and there is no interference from the ribs or lungs. 

You may have a TOE to check:

• your heart valves or heart muscle
• for any infection in your heart valves (endocarditis)
• for any blood clots
• for tears in your aorta (the largest blood vessel in your body)
• for any heart defects, such as a hole in the heart.

A TOE can also be used to guide your surgeon during heart procedures such as mitral valve surgery. You may also need to have it before an ablation for atrial fibrillation. 

Preparing for a TOE

TOE is usually done as a day-case procedure in hospital and is performed by a cardiologist (a doctor specialising in conditions of the heart).

Your doctor will explain how to prepare for your procedure. You will be asked to follow fasting instructions, which means not eating or drinking for six hours beforehand. 

You should take any other medication as usual and let your doctor know if you’re taking anticoagulants (medicines that help to prevent your blood clotting) such as heparin, clopidogrel or warfarin.

You will usually stay awake during the procedure and have a sedative. This relieves anxiety and helps you to relax.

Your doctor will discuss what will happen before, during and after your procedure, and any pain you might have. This is your opportunity to understand what will happen, and you may wish to prepare questions to ask about the risks, benefits and any alternatives to the procedure. This will help you to be informed, so you can give your consent for the procedure to go ahead.

What happens during a TOE?

The TOE procedure usually takes about 30 minutes. The procedure will take place in a TOE/anaesthetic room. You will be given a hospital gown and you will be asked to lie down on a bed. 

You will be asked to remove any dentures or dental plates, contact lenses, glasses and jewellery. 

If you are having a sedative, this is usually given through a fine tube (cannula) into a vein in your arm. Sedatives can sometimes affect your breathing, so we will give you extra oxygen and the doctor will monitor the amount of oxygen in your blood during the procedure. Your heart rhythm will also be monitored throughout the TOE.

You will be asked to lie on your side with your head tilted slightly forward. The doctor will spray a local anaesthetic into the back of your throat and place a plastic guard over your teeth before putting the sensor in your mouth. 

He or she will then ask you to swallow to allow the sensor to pass into your oesophagus.

The sensor will send out sound waves and pick up the returning echoes. Pictures of the inside of your heart will be displayed on a screen. These pictures are constantly updated, so the scan can show movement.

Sometimes a contrast liquid may be injected into your vein during the test. This helps to show certain parts of your heart more clearly.

The test is painless but may feel uncomfortable when the sensor is passed into your oesophagus.

What happens after a TOE?

You will need to rest until the effects of the sedative have passed. You should then be able to go home when you feel ready and the doctor says it is OK to do so. 

You will need to arrange for someone to drive you home and have a friend or relative stay with you for the first 24 hours.

After a local anaesthetic, it may take several hours before the feeling comes back into your mouth and throat. Don’t try to eat or drink until you can swallow normally. 

You will be given a few sips of water before you leave the ward to check you can swallow. Once you’re able to swallow, start with fluids and then move onto food. You should not drink anything hot until the effects of the local anaesthetic have fully worn off.

Sedation temporarily affects your co-ordination and reasoning skills, so you must not drive, drink alcohol, operate machinery or sign legal documents for 24 hours afterwards.

If you are in any doubt about driving, contact your motor insurer so that you are aware of their recommendations, and always follow your doctor’s advice.

The results of your TOE are usually sent to the doctor who requested your test. He or she will discuss the results with you at your next appointment.

What are the benefits of a TOE?

A TOE will only be recommended where information about the structure and function of your heart (how it works) cannot be obtained using a standard echocardiogram taken from the front of the chest. 

The better quality and clarity of ultrasound pictures which can be achieved from a TOE procedure can be used to guide your treatment in the future. 

It also provides additional information to other imaging techniques (such as cardiac magnetic resonance scanning, nuclear medicine scanning, and cardiac angiography) and your doctor will explain the choice of procedure with you. 

You may also want to discuss the effects of not having the procedure with your doctor. 

What are the potential risks and complications of a TOE?

All medical procedures are associated with a degree of risk; however, a TOE is considered to be a relatively safe procedure.

There are small risks associated with having sedation/anaesthesia, and the anaesthetist (or doctor performing the TOE) will discuss these with you. 

The greatest risk will relate to the severity of your underlying heart disease and your doctors will also discuss this with you. There are small risks associated with the procedure itself.

Side effects include:

• a sore throat or hoarse voice
• and/or bruising at the site where the sedation/anaesthetic injection was given.

Rare complications include:

• damage to your teeth or dental work, such as crowns
• damage or tearing to your oesophagus
• an allergic reaction to the sedative or contrast agent, such as a skin rash, difficulty breathing or heart problems.