Echocardiography is ultrasound imaging of the heart. It is essential in the diagnosis and evaluation of many cardiac disorders.
How does it work?
Echocardiography uses a transducer that emits high-frequency (ultrasonic) waves. These waves travel through body tissue and are reflected at interfaces where there are differences in the adjacent tissues. The reflected waves travel back to the transducer which then uses this information to generate an image.
Transesophogeal echocardiography (TEE), in particular, uses a miniaturized transducer mounted on the end of a modified endoscope. The endoscope, when inserted in the esophagus, is then so near the heart that it can transmit and receive ultrasound waves to create very clear images of the neighboring cardiac structures.
What does the procedure involve?
Children undergoing TEE are anaesthetized. However, adults are usually put under conscious sedation. This involves using a sedating benzodiazepine and an opiate pain reliever to ease discomfort and decrease the gag reflex. Sometimes a local anesthetic spray is used for the back of the throat. You will also have to fast prior to the procedure so that your stomach will be empty.
Are there risks?
TEE is considered an invasive procedure and is done by a physician. There is about a 1 in 10,000 risk of esophageal perforation. There is also a risk of adverse reactions to the medications used for sedation.
Why do they have to go down my esophagus just to image my heart?
Ultrasound imaging of the heart is frequently done with the transducer on the outside of the chest wall. This is called transthoracic echocardiography (TTE). However, with this technique the ultrasound waves have to penetrate through skin, fat, ribs and lungs before bouncing off the heart. This degrades the image and, because of the way your heart is situated in your body, some cardiac structures are very poorly visualized.
Your doctor may request a TEE, rather than a TTE, for you because of one or more of the following reasons:
-You have chronic obstructive lung disease (COPD) that interferes with imaging.
-You have prosthetic heart valves that interfere with imaging.
-You have/had cerebral ischemia (stroke) and they need to be very sure there are no emboli in your heart to cause further strokes.
-They want to look closely at aortic and/or atrial abnormalities which are seen best with TEE.
-They want to look for aortic dissection (separation and bleeding into the layers of your aortic vessel wall).