When ultrasound from the outside is not enough, the TEE looks from within. In Switzerland you will often hear it called the "Schluckecho", the swallow echo. In transoesophageal echocardiography (TEE), we pass a slim ultrasound probe through the mouth into the oesophagus. The oesophagus lies directly behind the heart, so from this position we obtain very sharp images of the heart valves, the atria and the aorta. At Dein Team Herzzentrum the examination is performed on an outpatient basis and, in the great majority of cases, under light sedation. You remain responsive and breathe on your own throughout.
What is a TEE and when do you need it?
The TEE, in full transoesophageal echocardiography, is an ultrasound examination of the heart performed through the oesophagus. A finger-thick probe with a transducer at its tip delivers high-resolution images, because only a few millimetres of tissue separate the oesophagus from the heart. This lets the TEE show structures that ultrasound through the chest wall (TTE) often cannot depict precisely enough. Typical questions are blood clots in the left atrial appendage before a cardioversion, suspected infection of a heart valve (endocarditis), leaking or narrowed valves, the assessment of an artificial heart valve and the search for a connection between the atria. The 2023 ESC guideline classifies the TEE as a Class I recommendation for suspected left-sided endocarditis, even when the TTE was already abnormal [ESC 2023]. The examination usually takes 10 to 20 minutes.
Why the TEE produces sharper images than a standard heart ultrasound
With ultrasound through the chest wall, ribs, lung and fatty tissue sit between the transducer and the heart. These structures weaken the sound waves. The oesophagus, by contrast, lies immediately next to the left atrium and the aorta. The result is a markedly higher image resolution for exactly those regions that are hard to see from the outside.
The left atrial appendage in particular, a small pouch of the left atrium, can only be assessed reliably with the TEE. This is precisely where blood clots tend to form in atrial fibrillation. The Swiss Heart Foundation points out that in atrial fibrillation clots can form in the appendage, be swept out and cause a stroke in the brain [Schweizerische Herzstiftung]. The risk of stroke is roughly four to five times higher with atrial fibrillation.
When a TEE makes sense before a cardioversion
Before atrial fibrillation is converted back to a normal rhythm (cardioversion), a clot in the atrial appendage must be ruled out. The 2024 ESC guideline lowered the threshold for early cardioversion from 48 to 24 hours. If the atrial fibrillation has lasted longer than 24 hours, an early cardioversion should only take place after adequate anticoagulation or after a TEE [ESC 2024]. Here the TEE can show a clot directly and so make an earlier cardioversion possible, without waiting through several weeks of anticoagulation.
| Question | What the TEE clarifies |
|---|---|
| Atrial fibrillation before cardioversion | Clot in the left atrial appendage, yes or no |
| Suspected endocarditis | Deposits (vegetations) on the valves |
| Artificial heart valve | Function, leaks, deposits |
| Mitral or aortic valve disease | Exact extent before an intervention |
| Stroke of unexplained cause | Connection between the atria, aorta |
How the examination runs at Dein Team Herzzentrum
You lie on your left side. The throat is numbed with a local anaesthetic, usually combined with light sedation given through a vein. We then pass the probe through the mouth and ask you to swallow once. During the examination you usually feel only a sensation of pressure in the throat. You keep breathing and swallowing, and you remain free of pain.
We work in pairs for the entire procedure, a physician and a medical professional, and monitor your pulse and oxygen saturation continuously. For sedation we mostly use propofol or midazolam. Both are short-acting, so after a recovery period you are awake and orientated again. If you wish and the situation allows, the TEE can also be performed without sedation; you can then drive yourself home directly afterwards.
During the examination the physician slowly rotates the probe and images the heart from several angles. As soon as all questions have been answered, the probe is withdrawn promptly. We often discuss the key findings with you directly afterwards, as soon as you are responsive again.
Preparation: come with an empty stomach
The upper digestive tract must be empty so that the probe has a clear view and nothing is aspirated. The usual points are these:
- Nothing to eat for about six hours before the appointment. Clear fluids are usually allowed until around two hours beforehand; we clarify this with you in advance.
- Take necessary medication with a small sip of water, unless agreed otherwise.
- If you have diabetes, take blood-thinning medication or have known problems with the oesophagus, please check with us briefly beforehand.
- If sedation is planned, arrange for someone to accompany you home.
After the TEE
After sedation you may not drive a vehicle, operate machinery or sign legally binding documents on the same day. Wait to eat and drink until the numbness in your throat has worn off completely, otherwise there is a risk of choking. A slight scratchy feeling in the throat for a day is normal.
Please contact us immediately if severe abdominal or chest pain, difficulty swallowing, fever, vomiting of blood, dizziness or shortness of breath occur after the examination. Such symptoms are very rare, but they need prompt assessment.
How safe is the TEE?
The TEE is considered a safe procedure. Large analyses put the rate of serious complications at around 0.2 percent [Hilberath 2010, J Am Soc Echocardiogr]. The most feared complication, an injury to the oesophagus, is rare at a frequency of roughly 0.03 to 0.09 percent [TEE-Review 2024, PMC]. The risk rises with pre-existing conditions of the oesophagus such as pouches (diverticula) or varicose veins (varices). This is exactly why we ask specifically about swallowing problems and previous illnesses before the examination.
Before every TEE a physician informs you fully about the procedure, its benefits and its risks, and answers your questions. This consent discussion is a fixed part of our approach and no mere formality.
Frequently asked questions
What do I need to bear in mind before a TEE? Come with an empty stomach: nothing to eat for about six hours beforehand, clear fluids only as agreed. If sedation is planned, do not drive yourself on the day of the examination and bring someone to accompany you.
Is a TEE dangerous? It is a low-risk ultrasound examination that causes little discomfort. Serious complications occur in around 0.2 percent of examinations, an injury to the oesophagus even more rarely [Hilberath 2010, J Am Soc Echocardiogr]. With careful preliminary assessment and monitoring, the risk can be kept low.
Does the examination hurt? No. The throat is numbed and you usually receive light sedation. Most people feel only a sensation of pressure in the throat and afterwards barely remember the procedure.
Why is a standard heart ultrasound not always enough? With ultrasound through the chest wall, ribs and lung are in the way. The TEE looks at the heart directly from the oesophagus and shows the left atrial appendage, the heart valves and the aorta in particular far more precisely.
When is a TEE performed? When searching for clots before a cardioversion, when an infection of a heart valve is suspected, for the precise assessment of valve disease and artificial valves, and to investigate a stroke of unexplained cause. Where endocarditis is suspected, the TEE is the guideline standard [ESC 2023].
Do I always need a TEE before a cardioversion? Not always. If you have already been on blood thinners for long enough, the TEE can be omitted. If the atrial fibrillation has lasted longer than 24 hours and an early cardioversion is planned, the 2024 ESC guideline requires either a TEE or adequate anticoagulation [ESC 2024].
How long does the examination take? The examination itself usually takes 10 to 20 minutes. Including preparation, the consent discussion and monitoring afterwards, you should allow a few hours in total at Dein Team Herzzentrum, especially if you are sedated.