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A transthoracic echocardiogram (TTE) is an imaging technology that uses sound waves to examine the function and structure of the heart. It is often referred to as a cardiac echo, cardiac ultrasound, or a cardiac sonogram. This imaging study is typically done to evaluate conditions such as heart failure, diseases of the valves of the heart, and congenital heart defects. Most patients tolerate the procedure well, as it is a noninvasive test that only involves placing a transducing probe over the external chest wall.
The fundamental basis of echocardiogram is that it uses ultrasound waves, inaudible to the human ear, to characterize the body's internal structures. A transducer emits sound waves and measures the time it takes for these sound waves to be reflected back to the transducer. The technology allows for the construction of a two-dimensional image that shows solid structures and blood flows throughout the heart. A transthoracic echocardiogram uses a transducer placed on the external chest wall in order to obtain an image. In contrast, a transesophageal echocardiogram uses a probe inserted down the esophagus to visualize the heart, and therefore is a more invasive and complex procedure.
Doctors who decide to have a transthoracic echocardiogram done on a patient will obtain a wealth of information about the structure and function of the heart. They receive a report sketching out the size of the heart wall and the four chambers of the heart. Functional information regarding the flow of blood in the heart, including whether blood ever leaks backward through heart valves, is also provided. The results can also show whether there is any fluid buildup around the heart.
There are a number of reasons why physicians might want a patient to receive a transthoracic echocardiogram. One common reason for doing a TTE is to evaluate a patient for heart failure because the test provides information about how efficiently the chambers of the heart are pumping blood. Patients who are either found to have a heart murmur on physical exam, or who have a history of problems with their heart valves, might also receive this imaging study in order to evaluate the blood flow through the heart. Other reasons for obtaining a TTE can include assessing for congenital heart disease, fluid buildup around the heart, tumors located in or around the heart, or cardiomyopathy — a condition characterized by abnormalities in the muscle of the heart.
Some of the benefits of choosing a transthoracic echocardiogram is that it is easily performed, is well tolerated by most patients, and does not expose them to radiation. Experienced ultrasound technologists can perform a thorough evaluation in less than an hour. Patients do not have to be sedated or given any anesthetic medications because the test only involves the use of an external probe. Occasionally, less accurate results can be seen in patients who have a chest wall deformity that corrupts the transmission of the sound waves. Obese patients with a larger layer of subcutaneous fat also tend to have poorer quality results because the fat can distort the sound waves.