What is an echocardiogram?
An echocardiogram, sometimes just called an "echo test" or "heart ultrasound," is an ultrasound examination of the heart. The doctors who perform the test use an ultrasound transducer (probe), which can either be held against your chest from outside the body, or passed into the body through your esophagus (food pipe) at the tip of an endoscope (a long tube). The transducer produces sound waves beyond the range of human hearing (humans can't hear them). These waves are reflected back as an echo. The echoes reflected by the different types of heart tissue and the blood-filled chambers of the heart differ in intensity. This sound wave echo is used to create a moving black and white ultrasound image on a monitor.
The image shows the structure of the heart and makes it possible to assess the size of the heart chambers, how well the valves work, and the thickness of the heart muscle tissue. You can also watch the heart at work in real time and track the direction of blood flow or determine how well your heart can pump blood.
An echocardiogram is one of the main types of routine heart examinations. It is helpful in the diagnosis of many different types of heart disease and can be done without the use of radiation. There are different types of echocardiogram examinations, some of which can also be combined.
What types of echocardiograms are there?
The most common kind of echocardiogram examination, transthoracic echocardiograms (TTE), involve placing the transducer on the the front of your chest. TTE is a simple, fast and cost-effective method. This test alone can provide a lot of information about the heart's chambers, valves and muscle, and the performance of the heart. The following examinations are also sometimes used:
- 3D imaging of the heart: Special transducers can be used to provide a three-dimensional image of the heart. This type of examination is most often used to assess the functioning of the heart in people with heart failure.
- Doppler ultrasound and color Doppler ultrasound: A Doppler ultrasound can be used to see the flow of blood. A color Doppler ultrasound can also show the direction of blood flow in different colors. This is done by using sound waves of a specific frequency. The flow rate can also be measured at the same time. The resulting images will show any valve defects or holes in the cardiac septum (the wall dividing the right and left sides of the heart).
- Stress test: An echocardiogram can also be done while the heart is being subjected to additional stress. In the "stress test" the performance of the heart is increased through physical exercise (for example with an exercise bike) or special medications. These medications increase the heart's need for oxygen and are injected into a vein in your arm. Signs of circulation problems in the coronary arteries, such as heart wall movement disorders, can be seen indirectly when the heart is under stress.
Sometimes a contrast agent (which works as a dye) is injected into a vein too, so that doctors can observe how the blood is distributed throughout the heart when the heart has to work harder. Areas that do not receive a lot of blood show less color because they also have less of the contrast agent in them.
An echocardiogram through your food pipe (esophagus) (TEE)
TEE (transesophageal echocardiogram) uses a transducer mounted at the end of a long, flexible tube that is carefully inserted into your food pipe through your mouth. This is similar to how gastroscopy is done. Because the food pipe is located right behind the heart, this examination can deliver more exact images than an echocardiogram done from outside the body.
TEE is especially good at examining the atria and the valves of the heart. It is often used in people who have atrial fibrillation to look for blood clots in the atria, or to see if there is a bacterial infection of the heart valves (endocarditis). TEE is also better than TTE at detecting aortic aneurysms (enlargements of the aorta) and congenital heart defects.
What can echocardiograms show us?
The ultrasound images in an echocardiogram provide different kinds of information, including the following:
- Changes in the valves of the heart
- Congenital birth defects such as a hole in the heart wall (septum)
- Diseases of the muscle tissue of the heart (cardiomyopathy)
- Disorders affecting the sac around the heart (pericardial disease)
- Problems with the flow or pumping of blood through the heart
- Changes in the heart that could be signs of pulmonary embolism or possible aortic aneurysm
It is also possible to use an echocardiogram to get a more exact idea of which parts of the heart have been damaged in people who have coronary artery disease (CAD) or who have had a heart attack. If an electrocardiogram (ECG) shows abnormal results, having an echocardiogram too could provide more information.
Echocardiograms can't show the individual coronary arteries, though. Cardiac catheterization would be needed for that. But the ultrasound images may offer indirect evidence of blood flow problems in the coronary arteries. For example, if certain areas of the heart show less movement than normal, it could be a sign of poor blood flow in the coronary arteries.
How can you prepare for an echocardiogram?
You usually don't need to prepare for a standard echocardiogram that will be done from outside of your body.
If the transducer needs to be swallowed (TEE), you should not eat anything for at least four hours before the examination. You can eat and drink again about one or two hours after the examination.
What happens during the examination?
Before having the echocardiogram, you will be asked to undress from the waist up. You will usually have to turn to your side a little, and your upper body may be elevated a bit. As with any ultrasound examination, the doctor will put some gel on your skin. Light pressure is applied as the transducer is moved across your chest. The images that appear on the monitor can then be analyzed and saved immediately.
In TEE a long, flexible tube is gently inserted into your mouth and moved into your esophagus. Actively swallowing as it goes down helps. A local anesthetic can be used on the back of your throat if the gag reflex is too strong. Sometimes a mild sedative is also used. Afterwards, you should not drive or ride a bicycle for the rest of the day.
Are there risks involved?
If the examination is done using a transducer outside of your body, it isn't associated with any risks. Ultrasound tests do not emit any radiation.
People sometimes find it difficult to lie on their side during the examination – particularly people who are older and frail, or who are short of breath. It is also possible to have an echocardiogram while lying on your back, but the image quality is a little worse.
TEE may trigger a gag reflex or increased salivation. Food pipe injuries are very rare.
If a contrast agent is used, it may temporarily cause a headache, nausea, anxiety or problems with eyesight and hearing.
The risks associated with stress echocardiograms are similar to those associated with stress electrocardiograms (ECGs). Doctors need to determine in advance whether you have heart disease that would make physical exertion dangerous.
If local anesthetics, sedatives or contrast agents are used during the test, side effects such as allergic reactions or breathing problems are possible.
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