Echocardiogram

n echocardiogram can be used to find out if there is an abnormality of the heart that could lead to stroke.  There are two types of echocardiograms:  one that examines the heart through the chest (called transthoracic echocardiogram, or TTE), and one that examines the heart through the throat (called transesophageal echocardiogram, or TEE).  The information that follows applies only to the use of these procedures in a stroke evaluation.

Transthoracic echocardiogram is most commonly performed, and it is a test  that gives information about the size of the heart chamber, the motion of the heart walls, the movements of the heart valves and changes in structure in and around the heart.  Ultrasound waves (the same ones used in imaging the fetus in a pregnant woman) are used to make an image of the heart's walls and valves.

Transesophageal echocardiogram is provides images of the internal structures of the heart and its blood vessels using the same ultrasound technology.

Why do doctors use echocardiogram?
Doctors often use TTE on patients in whom they suspect blood clotting (called cardiac embolus), since clots that form in the heart can be detected using this procedure.  Blood clots are a leading cause of stroke, as 80% of all clots in the heart eventually come loose and travel to the brain.  An echocardiogram can help determine how to treat or prevent a stroke (if a blood clot is found in the heart, a blood-thinner such as Warfarin may be prescribed).  TTE is performed routinely after heart attack and as part of a stroke evaluation.    

Transesophageal echocardiogram (TEE) is usually prescribed after an abnormality is found in the results of a TTE.  The images from TEE can provide more information about the condition of the heart because they have better resolution and are taken from the inside of the body rather than the outside.

What happens during echocardiogram?
In TTE, a clear gel is placed on the area of the chest where the heart is located. This lubricating gel allows a device that both puts out and detects ultrasound signals (called an ultrasound transducer) to slide around easily on the skin. 

When the transducer is placed against the skin, a picture of the area is shown on a video screen. Depending on how the transducer is positioned, the heart can be viewed from several different angles. Due to blood flowing through the heart, a sound similar to your heartbeat will be heard.  

A dye, called agitated saline, may be injected to find any leaking between the chambers of the heart.  

The images, stored as a 15-minute recording, will be viewed later by the physician.  TTE requires about 45 minutes to complete.

TEE, unlike TTE, requires preparation before the test can be done. You will be asked not eat or drink anything except water during the eight hours before the test. You should also not smoke for six hours before the test is done. Be sure to ask your doctor how you should adjust your daily medications, such as insulin if you are diabetic. 

During the actual procedure, you will be sedated intravenously to make it less uncomfortable. The doctor will then ask you to swallow a thin, flexible tube with a special tip (called a probe).  You may be asked to gargle an anesthetic that will numb your throat and tongue so that you can swallow the probe more easily.  The test takes 60-90 minutes to complete, but you may have to stay for one or two hours so that the sedative can wear off.

What are the risks of echocardiogram?
Since TTE is done without entering the body and does not use dyes, there is no risk or pain in having a TTE.
In TEE, the swallowing of the probe may cause some discomfort or pain.  However, anesthetics are usually given to make the procedure less uncomfortable.

How does echocardiogram work?
The transducer, or probe, emits high-frequency ultrasound waves that pass into the body and bounce off the valves of the heart and the muscles of the heart walls. The sound waves are reflected differently by different parts of the body. The transducer detects the different reflections of the sound waves, which are then measured and converted into live pictures of the heart by a computer.  These images are recorded on video tape and later viewed by your doctor.

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