A transoesophageal echocardiogram (TOE) is a special echo study that involves swallowing a thin probe. It allows images of the heart to be taken from the gullet.
This gives us incredibly clear images of the heart, valves and your aorta (the main artery coming out of your heart).
What does it involve?
You will start off in the cardiac ward. A nurse will give you a gown to wear instead of your clothes (you can keep your underwear on). A small plastic cannula will be inserted into your arm or the back of the hand. This is so we can give you medication or sedation.
I will explain the procedure and get your written consent. You will then be taken to the echo room. An anaesthetic solution will be sprayed into the back of your mouth to make it numb. You will then be asked to lie on your left side. A blood pressure cuff will be put on your arm and an oxygen monitor clip put on your finger. If you have sedation, this will be given you you through the cannula and you will be given extra oxygen to breath.
A mouthguard will be placed between your teeth and the probe passed into the back of your mouth. You will be asked to breath in and out through your nose and try to swallow the probe – imaging it is a large boiling sweet! Once it slips into your gullet, it will feel better. While the images are being taken, you should try to keep still and avoid coughing or retching as much as possible. A nurse will suction away any saliva from your mouth.
Sometimes we combine a TOE with a bubble study — in this case, you will also get an injection of saline into your arm cannula (see bubble study).
What preparation is needed?
Since a probe is passed into your gullet and stomach, this can make you want to retch. It is therefore vital that you have an empty stomach. You will be asked to fast for 4 hours prior to the procedure. Please bring a list of medications with you. If you are on warfarin, it will be useful to see your little yellow book of INR results. Please tell me if you have problems swallowing food or have had an operation on your gullet.
How long does it take?
The actual procedure takes just a few minutes to do, depending on how much of the heart needs to be assessed. However, you will be monitored for a while after the procedure, especially if you have had sedation. You should allow 2-3 hours as a minimum and possibly longer if you need sedation.
What happens after
You will be taken back to the ward. Since your throat is numb, you cannot eat or drink for up to 90 minutes afterward (you may choke without realising it or scald yourself on hot tea). When the anaesthetic wears off, the nurse will assess your swallowing with a sip of water. If all is well, you can eat and drink and will be discharged.
If you have had sedation, you should not drive or operate heavy machinery for 12 hours after. It is therefore important that you have someone else to take you home.
Where can it be done?
TOE can be performed at The Oaks, Colchester Hospital or the Essex Cardiothoracic Centre.
Each centre uses different machines and occasionally one centre may be recommended over another for technical reasons. The best place to have the procedure will be explained to you in the clinic.
What are the risks?
TOE is a bit unpleasant and will make you feel like gagging. Fortunately the study is usually quite short. It is not painful.
On rare occasions, the probe can cause some bleeding in the mouth or gullet. In exceptional circumstances, the probe can tear the gullet. This is so rare, I have never seen a case, nor met a consultant who has either — it is described in the textbooks though. If you were to develop severe pain in your chest in the 24 hours after the procedure, you should seek medical help immediately.
What are the benefits?
TOE allows very clear pictures of you heart. The image quality is far superior to that obtained from a standard echo. It is particularly good for looking for holes in the heart, clots in the chambers and for assessing the structure and function of heart valves. The latest machines can even capture a 3D image, which helps a surgeon visualise the problem with a heart valve before he actually operates.