Stanford Cardiac Arrhythmia Service


Echocardiography is an ultrasound examination of your heart.  Sound waves create a moving picture of your heart, giving us information about its size and shape, and how well your heart chambers and valves are working.   The Table 1 indicates the range of information that echocardiography may provide.  Echocardiography is a commonly used method to assess the function of the heart chambers.  The function of the left ventricle is one of the most important measurements that is made. The Ejection Fraction or EF is a common measure of the function of the left ventricle, the main pumping chamber that pumps blood to the entire body.  The Ejection Fraction is percentage of blood pumped out with each heart beat.  The Ejection Fraction is calculated by the dividing the total amount of blood that fills the main heart chamber by the amount of blood pumped out with each heart beat.   The normal Ejection Fraction is about 60%.
Echocardiography is used as a noninvasive and safe method of assessing heart function. It does not involve exposure to radiation and therefore is suitable for repeated measurements over time. 

There are several different types of echocardiography, including transthoracic, transesophageal, and intracardiac echos.  
The transthoracic echo, or TTE, takes images from the surface of the chest.  It is performed by a technician called an echo sonographer or a physician.  Gel is placed on a hand-held probe (see figure and the probe is placed firmly on the patient’s chest in a variety of positions. The patient may be asked to lie on his or her back or left side.  These positions allow the echocardiogram to see different parts of the heart well.  The transthoracic echocardiogram is the most commonly used form ofin echocardiography because it is the easiest and safest to obtain. The quality of the images may be affected by the patient’s body characteristics. In some patients there may be some limitations of imaging because of these differences.


(Figure from

The transesophageal echo, or TEE, takes images from a probe placed into the mouth and into the esophagus and stomach.  Transesophageal echocardiography is recommended usually when very specific part of the heart need to be imaged with greater resolution.    The ultrasound or echocardiogram probe is placed into the mouth and down the esophagus (patient’s tube used to swallow) after the patient has been sedated.  The reason transesophageal echocardiography may provide a more detailed image is that the esophagus is immediately behind the heart.
Patients receive intravenous medication to make this exam more comfortable.  This exam allows us to see better definition of structures within the heart, and it can be especially helpful for identifying clots or infections.

Table: Transesophageal Echocardiography: Common Conditions

Part of Heart

Feature being examined


Left Atrium

Evaluate for blood clot prior to converting atrial fibrillation to normal rhythm



Evaluate for dissection or aneurysm; identify plaque as cause of stroke or embolism


Heart Valves

Evaluate for evidence of infection – called vegetations; Evaluate for abnormalities of structure such as tear or rupture of valve or valve structures; Quantify degree of leakiness or narrowing (stenosis)





















The intracardiac echocardiogram can take pictures from inside the heart.  This is usually reserved for use with other procedures with catheters in the heart and it can show the position of these catheters within the heart.  The intracardiac echo can increase the safety of procedures within your heart.

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