TOE is a detailed ultrasound assessment of the heart using a special endoscope (a flexible tube) with an ultrasound transducer that produces ultrasound waves. The probe is passed through your mouth into the oesophagus (food pipe) just behind the heart. The word 'transoesophageal means 'through the oesophagus'. The transducer sends ultrasound into the heart and then receives the echo, i.e. the bounce-back signals. The signals are transformed into pictures that are shown on a screen.

Transesophageal echocardiography (TOE) is used if the transthoracic echocardiogram (TTE) doesn’t produce clear results. Compared with transthoracic echo, TOE provides clearer and sharper images because the distance from the probe to the heart is much shorter, and the ultrasound waves don’t have to pass through the chest wall and lungs. TOE is superior to TTE in the evaluation of heart valves, both atria (top heart chambers), atrial septum, left atrial appendage (a muscular pouch connected to the left atrium where blood clots can sometimes be found in atrial fibrillation), aorta and pulmonary artery. The TOE also has some disadvantages; it may be uncomfortable, usually requires mild sedation (medicine to help you relax, e.g. Midazolam). As a semi-invasive test, it has a small but non-zero risk of complications.

TOE is usually a one-off procedure; if echo follow-up is necessary, a standard transthoracic (surface) echo is normally sufficient.

Indications
 

• Poor image quality with transthoracic echocardiography
• Detailed assessment of heart valves, especially prosthetic (artificial) valves
• Suspicion on infective endocarditis (infection affecting heart valves)
• Detection of thrombus (blood clot) within the heart before cardioversion (jump-starting the heart with electric shock, e.g. in atrial fibrillation)
• Investigation of possible cardiac sources of emboli (dislodged blood clots)
• Evaluation of atrial septum, atrial septal defect (a hole in the heart) and atrial septum aneurysm (floppy septum)
• Investigation of cardiac masses
• Evaluation of aorta, presence and severity of aortic atheroma/atherosclerosis (thickening of the wall of the vessel) and aortic dissection (medical emergency with partial rupture of the aortic wall)
• Intraoperative monitoring in cardiac surgery to assess the adequacy of valve repair
  
  

Risks and complications

Transoesophageal echocardiography is a very safe procedure. Dr Ruzicka will explain possible risks in detail, and you will be asked to sign informed consent. The complications involve soreness in the mouth and throat due to manipulation with the probe, damage to teeth (with a plastic mouth guard in place, the risk is minimal), perforation of the oesophagus (risk is about 1:10,000) and somnolence from sedation.

Before the procedure

Do not eat or drink anything from midnight before your appointment. Please do not stop any medication, particularly anticoagulants (warfarin, apixaban, edoxaban, rivaroxaban, dabigatran). You can drink water, clear tea and black coffee (without milk) up to 2 hours before the procedure. You can consume milk, food, sweets, tea or coffee with milk up to 6 hours before the procedure. Chewing gum and smoking are not permitted on the day of the test. Please bring the list of your medication with you. If you have diabetes, please do not take your diabetic medication but bring it along with some food to eat after the investigation is completed. You will be asked to remove any full or partial dentures. Dr Ruzicka will explain the test and answer any questions you may have before signing the consent form. A small cannula will be inserted into your arm. Three ECG electrodes (plastic stickers) will be placed on your right side, left and right shoulder and attached to the echo machine.

During the procedure

Dr Ruzicka will use an anaesthetic spray (e.g. Xylocaine spray) to numb the throat and will give you a small dose of sedation (medicine to help you relax, e.g. Midazolam). A saturation probe and blood pressure cuff will be attached to monitor the oxygen level in the blood and blood pressure. You will then be asked to open your mouth, and the probe with a lubricant will be gently introduced into the gullet (= oesophagus). If necessary, the sedation can be titrated up during the procedure. A nurse may give an oxygen mask to help with breathing. The difficult part of the test is the swallowing of the probe, but once it is down in the oesophagus, the procedure becomes much more comfortable. The procedure takes approximately 20-30 minutes.

After the procedure

It can take up to 30 minutes for your throat to return to a normal feeling. You will then be able to eat and drink normally. You will remain in the department for 1-2 hours and have some refreshments. Before you are discharged, Dr Ruzicka will shortly talk to you about the test result and any follow-up arrangements. Because of the sedation, it is best to discuss the results in detail in a separate session and have someone pick you up from the clinic and stay with you for the rest of the day.

If sedation is administered, it can remain in your system for 24 hours, you should until then:
   - Have someone to take you home and stay with you
   - Not drive (you will not be covered by insurance)
   - Not return to work
   - Not operate any machinery, including domestic appliances
   - Not drink alcohol
   - Not sign any important or legal documents