What is echocardiography?
Echocardiography is a procedure used to assess the heart structures and function. Echocardiography is also called echo, cardiac ultrasound or ultrasonography, cardiac Doppler or transthoracic echocardiography (TTE).
A small probe called a transducer is placed on the child’s chest and sends out ultrasonic sound waves at a frequency too high to be heard. When the transducer is placed on the 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 interprets the echoes into an image of the heart walls and valves.
What are the different types of echocardiography?
An echocardiogram can utilize one, or more, 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 such problems as an 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 and velocity (speed) of blood flow. This simplifies the interpretation of the Doppler images.
- 2-dimensional (2-D) echocardiography
This technique is used to see the actual structures and 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.
- Transthoracic Doppler Echocardiography
An ultrasound procedure used to visualize the internal cardiac structure and evaluate the blood flow within the heart.
- Tissue Doppler Velocity Imaging
This modality allows the speed of heart muscle motion to be measured. This enables of diagnosis of loss of heart muscle strength, such as may occur in heart transplants with chronic coronary artery disease.
- Real-time 3-D Imaging
This technique creates, for the first time, images of the living heart as a surgeon might see it. The ultrasound imaging is completely noninvasive. Abnormalities, such as valve defects can be examined, allowing specific localization of malfunctioning regions which may be causing leakage of blood from one chamber of the heart into another.
- Intra-operative Transesophageal Echocardiography
Performed during and after cardiac surgery, this procedure utilizes a special ultrasound probe that is placed in the esophagus to image the heart structure and evaluate blood flow within the heart so cardiologists and cardiac surgeons can accurately gauge the effects of the surgical procedure.
- Fetal Echocardiography
This specialized ultrasound procedure is performed by specially trained cardiac sonographers to image and evaluate the fetal heart during pregnancy. If a defect is found, the medical team will have ample time to prepare the family and plan corrective actions and other interventions.
What problems can echocardiography diagnose?
Several diseases of the heart may be detected by echocardiography, including the following:
- Aneurysm—a dilation 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) which may cause a weakness of the tissue at the site of the aneurysm.
- 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 build up (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.
How is an echocardiogram performed?
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, parents will be allowed to stay with their child to provide reassurance during the procedure.
- The technician will need to see the child’s chest from the waist up. Privacy will be maintained by drapes across the child’s chest and by limiting access into the procedure area.
- ECG electrodes will be attached to the child’s chest with adhesive patches.
- The child will lie on a table or bed during the procedure. A pillow or wedge may be placed behind the 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 the child’s chest and then place the transducer probe on the gel. The child will feel a slight pressure as the technician positions the transducer to get the desired image of the 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 the child’s heart. The amount of pressure behind the probe should not be uncomfortable, but if it makes the child uncomfortable, he should let the parents or the technician know.
- After the procedure has been completed, the technician will wipe the gel from the child’s chest and remove the ECG electrodes.
In order to obtain clear pictures, it is important for children who are old enough to cooperate to try to be still during the echo. Parents can usually be involved in reassuring and encouraging their child during the procedure. However, an echo 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 medicine (sedative) to help relax them during the echo. A nurse will monitor the child during the procedure if sedation is administered. For safety reasons, parents will need to remain at the echo clinic until the 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.