What is an echocardiogram?
An echocardiogram is a type of ultrasound that uses sound waves to produce images of the heart. High-pitched sound waves are sent through a transducer and then bounce off the heart. The transducer receives the echoes of these sound waves and converts them to moving pictures of the heart that are seen on a video screen.

Echocardiograms provide a variety of information, including:
– Size of the heart
– Pumping strength of the heart
– The presence and extent of damage to myocardium
– Valvular disease
– Structural abnormalities

What are the different types of echocardiograms?
Transthoracic echocardiogram (TTE)
– Most common type
– Pictures are obtained by moving the transducer as required over the chest/abdominal wall
– This test is chosen to:
o look for causes of abnormal heart sounds, hypertrophy of the heart, unexplained chest pains, shortness of breath, or irregular heartbeats
o examine the thickness and movement of the walls of the heart
o examine the valves and their functionality
o measure the shape and size of the heart’s chambers
o examine the ability of the heart’s chambers to perform fully à ejection fraction may be measured
o detect disease that affects the myocardium and the heart’s function (eg cardiomyopathy)
o detect clots and tumours in the heart
o detect congenital heart defects
o examine the heart’s function following an infarction
o identify a specific cause of heart failure
o detect a pericardial effusion or a thickening of the pericardium

Transoesophageal echocardiogram (TOE or TEE)
– Pictures are obtained by passing a probe down the (sedated and anaesthetised) oesophageus
– Shows clearer pictures of the heart because the probe is physically located closer to the heart, and there is not interference from the lungs and sternum/ribs
– This test is chosen to:
o monitor heart function during surgery
o examine the function of an artificial heart valve
o detect masses and clots in the left atrium
o identify a cardiac shunt (abnormal blood flow through chambers)
o detect endocarditis
o guide procedures performed during cardiac catheterisation
o detect an aortic dissection

Stress echocardiogram
– Pictures are taken immediately before and immediately following exercise (walking on a treadmill/cycling on stationary bike) à if unable to physically exercise, a chemical (dobutamine) is injected into the bloodstream to stimulate the heart to beat faster and harder, as in exercise
– This test is chosen to:
o identify and monitor ischaemia/coronary heart disease

Doppler echocardiogram
– When sound waves bounce off blood cells moving through the heart and its vessels, they change pitch
– These characteristic changes (Doppler signals) can help measure the speed and direction of blood flow in the heart
– Doppler techniques are incorporated into most TTEs and TOEs and may be used in stress echocardiograms
– This test is chosen to:
o measure the speed at which blood travels through the heart
o measure the blood pressure and speed of blood flow through the heart valves

Sources
http://www.webmd.com/heart-disease/echocardiogram, accessed 16/2/08
http://www.webmd.com/heart-disease/echocardiogram, accessed 16/2/08