What is Transesophageal Echocardiography?
Transesophageal echocardiography (TEE) is basically an echo study performed from behind the heart with a probe placed in the esophagus (food pipe). Since the esophagus lies just behind the heart, TEE produces clearer pictures of the heart’s movement than a standard echocardiography taken from outside the chest. This test is ideal for looking at the heart’s valves, communications within the heart, and for discerning blood clots in the heart.
What are the indications?
- To evaluate the cardiac chambers, especially the atria and their appendages, for the presence of a blood clot i.e. thrombus to rule out cardiac source of embolus in cases of strokes and in cases of severe mitral valve disease (mitral stenosis) before valvuloplasty and electric cardioversion for atrial fibrillation.
- To look for patent foramen ovale (small defect in the interatrial septum) in cases of unexplained stroke. The colour flow Doppler helps in detection of left to right shunt, whereas a contrast venous injection of agitated normal saline is useful in detection of a right to left shunt across the patent foramen ovale.
- To look for presence of vegetations on the cardiac valves or paravalvular or valvular abscess, to assess evidence of subacute bacterial endocarditis, in known valvular heart disease cases presenting with fever and a fresh murmur (abnormal heart sound).
- To assess the extent and nature of atrial septal defects and decide about the suitability of device closure, when regular transthoracic echo does not give a satisfactory picture.
- To assess the mechanics of prosthetic cardiac valves, when transthoracic echo is unable to provide sufficient information.
- To diagnose the aortic conditions like acute dissection, aortic trauma, etc.
What are pre-test instructions?
- Eight hours complete fasting prior to the test is essential. (even water is not allowed).
- To bring along all the prior investigations.
- A relative or a friend has to accompany the patient for this test.
How is the test performed?
Initially the patient is asked to gargle with viscous xylocaine 2% mixed in a glass of water. The patient should alert the technician and the doctor in case he/she has dentures, oral prosthesis, partly unstable tooth or history of dysphagia (difficulty in swallowing) or esophageal problems. Then, after taking the consent, the patient is asked to lie on a bed on the left side. Following this, xylocaine is sprayed into the throat for local anaesthesia, which is effective within few minutes and persists for 30-45 minutes after the procedure during which time patient should avoid any food or drink to avoid aspiration into the respiratory tract. Also, three ECG electrodes and leads are attached to the chest and arm. Then, the doctor will explain the procedure to the patient in detail and would then give a bite block (mouth piece) to be held between the teeth. Through this mouth piece, the probe which has a small transducer at its tip, is introduced slowly across the throat into the food pipe. Patient might experience some amount of gagging during this process, but once the probe passes across the throat this sensation reduces and then patient should continue slow and deep breaths till the procedure is completed. Once the echocardiographic examination with colour Doppler is over, the probe is gradually removed.
What are post-test instructions?
- After the test, patient should avoid any kind of hot and spicy food or drink for at least four hours. Thereafter, patient can resume with the regular diet.
The report would be given to patient along with the CD in about 30 minutes after the test is over.
What are the risks or complications?
- Sore throat and mild difficulty in swallowing is common after the procedure and rarely is prolonged for more than 24 hours.
- Minor complications such as transient hypoxia (reduced oxygenation), hypotension (fall in blood pressure), hypertension (rise in blood pressure), bronchospasm, heart block, arrhythmias occur in less than 3% of cases.
Major complications such as death, esophageal perforation, serious arrhythmia (abnormal heart rhythm, congestive heart failure and laryngospasm are uncommon and occur in less than 0.3% of patients