Echocardiography is a procedure used to assess the heart's structures and function. Echocardiography is also called echo, cardiac ultrasound or ultrasonography, or cardiac Doppler.
Two main types of echocardiography exist:
- Transthoracic echocardiography, or TTE. A small probe called a transducer is placed on your child's chest and sends out ultrasonic sound waves at a frequency too high to be heard. When the transducer is placed on your child's chest in certain locations and at certain angles, the ultrasonic sound waves move through the skin and other body tissues to the heart tissues, where the waves bounce (or "echo") off of the heart structures. The transducer picks up the reflected waves and sends them to a computer. The computer displays the echoes as images of the heart walls and valves.
- Transesophageal echocardiography or TEE. This is more invasive than a transthoracic echo discussed above. It involves sedation in order to place a probe into the esophagus, the swallowing pipe between the mouth and the stomach. The esophagus lies directly behind the heart, so TEE images provide higher-resolution images of certain parts of the heart.
An echocardiogram can utilize one, or more, of several special types of echocardiography, as listed below:
- M-Mode echocardiography. This is the simplest type of echocardiography, and produces an image that is similar to a tracing rather than an actual picture of heart structures. M-mode echo is useful for measuring heart structures, such as the heart's pumping chambers, the size of the heart itself, and the thickness of the heart's walls.
- Doppler echocardiography. This Doppler technique is used to measure and assess the flow of blood through the heart's chambers and valves. The amount of blood pumped out with each beat is an indication of the heart's functioning. Also, Doppler can detect abnormal blood flow within the heart, which can indicate problems, such as an abnormal opening between chambers of the heart, a problem with one or more of the heart's four valves, or a problem with the heart's walls.
- Color Doppler. Color Doppler is an enhanced form of Doppler echocardiography. With color Doppler, different colors are used to designate the direction of blood flow. This simplifies the interpretation of the Doppler images.
- 2-D (two-dimensional) echocardiography. This technique is used to "see" the motion of the heart structures. A 2-D echo view appears cone-shaped on the monitor, and the real-time motion of the heart's structures can be observed. This enables the doctor to see the various heart structures at work and evaluate them.
- 3-D (three-dimensional) echocardiography. This technique represents a further advance from two-dimensional echocardiography as it generates three-dimensional movies of the beating heart. This allows further characterization of a congenital heart defect.
- Stress echocardiography. This technique examines what happens to the heart during a period of stress, either produced by medications or by exercise. Images of the heart are examined during periods of stress and compared to the resting echocardiogram.
Several diseases of the heart may be detected by echocardiography, including the following:
- Aneurysm. A dilation or weakness of a part of the coronary arteries or the aorta (the large artery which carries oxygenated blood out of the heart to the rest of the body). In extreme cases, an aneurysm may rupture, which is an emergency situation, causing rapid blood loss out of the blood vessels. Occasionally an aneurysm may occur in the pulmonary arteries or surgical patch areas especially if any intervention, such as a balloon angioplasty, has been previously done.
- Cardiomyopathy. An enlargement of the heart due to thickening or weakening of the heart muscle.
- Congenital (present at birth) defects. Abnormalities or deficiencies in one or more heart structures that occur during formation of the fetus.
- Congestive heart failure. A condition in which the heart muscle has become weakened to an extent that blood cannot be pumped efficiently; thus, causing a buildup of fluid(congestion) in the blood vessels, lungs, feet, ankles, and other parts of the body.
- Pericarditis. An inflammation of the membrane (thin covering) that surrounds the heart.
- Valve disease. One or more of the heart's four valves becomes defective, or may be congenitally (since birth) malformed.
The test may be done in a cardiologist's office, in a clinic, at a hospital or medical center as an outpatient, or as an inpatient in a medical facility. In most cases, you will be allowed to stay with your child to provide reassurance during the procedure.
- The technician will need to see your child's chest from the waist up. Privacy will be maintained by drapes across your child's chest and by limiting access into the procedure area.
- EKG electrodes will be attached to your child's chest with adhesive patches.
- Your child will lie on a table or bed during the procedure. A pillow or wedge may be placed behind your child's back for support.
- The room will be darkened so that the images on the echo monitor can be better viewed by the technician.
- The technician will place gel on your child's chest and then place the transducer probe on the gel. Your child will feel a slight pressure as the technician positions the transducer to obtain the desired image of your child's heart.
- During the test, the technician will move the transducer probe around and apply varying amounts of pressure to obtain images of different locations and structures of your child's heart. The amount of pressure behind the probe should not be uncomfortable, but if it makes your child uncomfortable, he or she should let you or the technician know.
- After the procedure has been completed, the technician will wipe the gel from your child's chest and remove the EKG electrodes.
In order to obtain clear pictures, it is important for children who are old enough to cooperate to try to hold still during the echocardiogram. Parents can usually be involved in reassuring and encouraging their child during the procedure. However, an echocardiogram can be a lengthy procedure. Younger children may become restless during the test, preventing clear images from being achieved. For this reason, young children may be given a medication (sedative) to help relax them during the echocardiogram. A nurse will monitor the child during the procedure if sedation is administered. For safety reasons, you will need to remain at the echo clinic until your child has woken up fully and the medicine has worn off.
Depending on the results of the echo, additional tests or procedures may be scheduled to gather further diagnostic information.
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