ECHOCARDIOGRAPHY

DEFINITION

An echocardiogram (echo) is a test that uses high frequency sound waves (ultrasound) to make pictures of your heart. The test is also called echocardiography or diagnostic cardiac ultrasound and is routinely used in the diagnosis, management, and follow-up of patients with any suspected or known heart diseases.

HOW IT WORKS

There are three basic "modes" used to image the heart:

• two-dimensional (2D) imaging

• M-mode imaging

• Doppler imaging

An echo uses sound waves to create pictures of your heart’s chambers, valves, walls and the blood vessels (aorta, arteries, veins) attached to your heart.

• A probe called a transducer is passed over your chest. The probe produces sound waves that bounce off your heart and “echo” back to the probe. These waves are changed into pictures viewed on a video monitor.

• An echo can’t harm you.

Echo tests are done by specially trained technicians. You may have your test done in your doctor’s office, an emergency room, an operating room, a hospital clinic or a hospital room. The test takes about an hour.

• You lie on a table and a technician places small metal disks (electrodes) on your chest. The disks have wires that hook to an electrocardiograph machine. An electrocardiogram (ECG or EKG) keeps track of your heartbeat during your test.

• The room is dark so your technician can better see the video monitor.

• Your technician puts gel on your chest to help sound waves pass through your skin.

• Your technician may ask you to move or hold your breath briefly to get better pictures.

• The probe (transducer) is passed across your chest. The probe produces sound waves that bounce off your heart and “echo” back to the probe.

• The sound waves are change into pictures and displayed on a video monitor. The pictures on the video monitor are recorded so your doctor can look at them later.

WHEN ITS USED

• The size and shape of your heart, and the size, thickness and movement of your heart’s walls.

• How your heart moves.

• The heart’s pumping strength.

• If the heart valves are working correctly.

• If blood is leaking backwards through your heart valves (regurgitation).

• If the heart valves are too narrow (stenosis).

• If there is a tumor or infectious growth around your heart valves.

• Problems with the outer lining of your heart (the pericardium).

• Problems with the large blood vessels that enter and leave the heart.

• Blood clots in the chambers of your heart.

• Abnormal holes between the chambers of the heart.

• can help detect cardiomyopathies

RISKS AND BENEFITS

The biggest advantage to echocardiography is that it is not invasive (does not involve breaking the skin or entering body cavities) and has no known risks or side effects.

TWO DIMENSIONAL IMAGING

• 2D imaging is the mainstay of echo imaging and allows structures to be viewed moving in real time in a cross-section of the heart (two dimensions).

• It is used for detecting abnormal anatomy or abnormal movement of structures.

• The most common cross-sectional views are the parasternal long axis, the parasternal short axis, and the apical view. The gastric or subcostal and suprasternal views are also commonly used.

• Image: The most common two-dimensional imaging echo views. The first line illustrates the three planes (think of them as three plates of glass intersecting at 90°), the second line shows these three planes separated, and the third line shows the accompanying echo views. (a) Parasternal long axis; (b) parasternal short axis; (c) apical 4-chamber view (note, in the UK, the 4-chamber view is shown upside down). AV: aortic valve; LA: left atrium; LV: left ventricle; RA: right atrium; RV: right ventricle.

M-MODE IMAGING

• The M-mode echo, which provides a 1D view, is used for fine measurements.

• Temporal and spatial resolutions are higher because the focus is on only one of the lines from the 2D trace

• Image: M-mode image of (a) the aorta/left atrium and (b) the mitral valve, both in a healthy heart.

DOPPLER IMAGING

CW Doppler is sensitive, but, because it measures velocity along the entire length of the ultrasound beam and not at a specific depth, it does not localize velocity measurements of blood flow. It is used to estimate the severity of valve stenosis or regurgitation by assessing the shape or density of the output

• PW Doppler was developed because of the need to make localized velocity measurements of turbulent flow (it measures the blood-flow velocity within a small area at a specified tissue depth). It is used to assess ventricular in-flow patterns, intracardiac shunts, and to make precise measurements of blood flow at valve orifices.

http://www.heart.org/HEARTORG/Conditions/HeartAttack/DiagnosingaHeartAttack/Echocardiogram---Echo_UCM_451485_Article.jsp#.WlTlSCOB0b0

https://en.wikipedia.org/wiki/Echocardiography

#imaging #ultrasound