The echocardiogram is an ultrasound of the heart. Using standard ultrasound techniques, two-dimensional slices of the heart can be imaged. An echocardiogram is a painless procedure that uses sound waves and a computer to look at your beating heart. A device called a transducer sends high-frequency sound waves into your chest. The sound waves bounce
(echo) off your heart. A computer uses the echoes to create a moving picture of the heart.
A trained sonographer performs the test, then your physician interprets the results. An instrument that transmits high-frequency sound waves called a transducer is placed on your ribs near the breast bone and directed toward the heart. The transducer picks up the echoes of the sound waves and transmits them as electrical impulses. The echocardiography machine converts these impulses into moving pictures of the heart.
Echocardiogram works well for most patients and allows doctors to see the heart beating and to visualize many of the structures of the heart. Occasionally, because your lungs, ribs, or body tissue may prevent the sound waves and echoes from providing a clear picture of heart function, the sonographer may administer a small amount of a dye through an IV to better see the inside of the heart. Very rarely, more invasive testing using special echocardiography probes may be necessary. If the echocardiogram is unclear due to a barrel chest, congestive obstructive pulmonary disease, or obesity, your health care provider may choose to perform a transesophageal echocardiogram, or TEE. With TEE, the back of your throat is anesthetized and a scope is inserted down your throat. On the end of the scope is an ultrasonic device that an experienced technician will guide down to the lower part of the esophagus, where it is used to obtain a more clear two-dimensional echocardiogram of your heart.
The standard echocardiogram is also known as a transthoracic echocardiogram, or TTE. In this case, the echocardiography transducer (or probe) is placed on the chest wall (or thorax) of the subject, and images are taken through the chest wall.
Another method to perform an echocardiogram is to insert a specialised scope containing an echocardiography transducer (TOE probe) within the patient's esophagus, and record pictures from there. This is known as a transesophageal echocardiogram, or TEE. The advantages of TEE over TTE are that better pictures can be produced, since there is less tissue between the transducer and the structures that are being imaged. Also since the scope is closer to certain structures of the cardiovascular system they become more ammenable to adequate imaging. Such structures include the aorta, the pulmonary artery, the valves of the heart, and the left and right atria. These structures are usually well visualized on trans-esophageal echocardiography. While TTE can be performed easily and without pain for the patient, TEE may require light [sedation]] and a local anesthetic lubricant for the esophagus.
In addition to creating two-dimensional pictures of the cardiovascular system, the echocardiogram can also produce accurate assessment of the direction of blood flow and the velocity of blood and cardiac tissue at any arbitrary point using doppler radar. This allows assessment of cardiac valve areas and function, any abnormal communications between the left and right side of the heart, any leaking of blood through the valves (valvular regurgitation), and calculation of the cardiac output.
Exercise Stress Echocardiogram: An exercise echocardiogram is a diagnostic test that enables the physician to see images of the heart while it is at work. For an exercise echocardiogram, a standard transthoracic ECHO is performed. You will then be asked to walk on a treadmill (which will become increasingly faster and steeper) for a specified amount of time until a particular level of exercise is achieved. Once your heart is working at a certain capacity, another transthoracic ECHO will be performed. This test is usually performed under the supervision of a cardiologist, who can monitor your vital signs while the test is in progress.
Dobutamine Stress Echocardiogram: The Dobutamine stress test functions in the same manner as an exercise stress echocardiogram, except that the heart’s workload is not increased through physical exercise. Instead, a medication (Dobutamine) is given that increases the heart rate and workload, simulating physical exercise. After your initial echocardiogram is performed, your doctor will administer the Dobutamine through your intravenous (IV) line. You will feel your heart rate increase. Once your heart workload has increased to a specific level, your physician will perform another echocardiogram. This test is particularly helpful for people with who have physical limitations.
Transesophageal Echocardiogram (TEE): Because this procedure is more invasive, you will be given a mild sedative to help you relax during the test. You will probably receive this through an IV line. A numbing medicine will be sprayed in your throat to help make the procedure more comfortable. The transducer, attached to the tip of a thin, flexible tube, will be inserted down your throat and into your esophagus (the organ that connects your throat to your stomach). Your heart rate and other vital signs will be monitored. The test will last about an hour.