Echocardiography
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Definition of Echocardiography
Echocardiography is one of the most important non-invasive techniques used in the diagnosis of heart disease today.
Description of Echocardiography
Echocardiograms are obtained by reflecting high frequency sound waves (ultrasound) off various structures of the heart, then translating the reflected waves into one and two-dimensional images. The advantages of echocardiography over other diagnostic techniques are many. It is painless and ideal for diagnosing problems in children and pregnant women for whom X-rays would be inappropriate. It generally requires no preparation of the patient.
M-Mode and two-dimensional echocardiography is most commonly used for diagnosing conditions that require knowledge of the anatomy of the heart, such as valve disease, ventricular enlargement and congenital heart abnormalities. It is widely employed in the diagnosis of pericardial effusion (fluid around the heart) and is the best technique for diagnosing idiopathic hypertrophic subaortic stenosis, a condition in which a portion of heart muscle has become excessively thickened.
Echocardiography also is the preferred method for identifying intracardiac masses, such as tumors and blood clots. It can be used to monitor the effectiveness of treatment for high blood pressure by taking periodic measurements of the size of the left ventricle and the thickness of its wall. Recent studies have shown that left ventricular enlargement diminishes with effective hypertension treatment.
When combined with the Doppler technique, which records changes in frequency of sound waves, echocardiography can be used to measure blood flow through heart valves and calculate pressure differences across valves. Doppler echocardiograms are an effective method to determine the degree of narrowing, calcification or leakage of a valve. The technique also provides measurements of blood flow within the heart's chambers to assess their function while pumping and resting (systolic and diastolic function), and blood flow in the major blood vessels and peripheral vessels in the arms and legs.
Echocardiography techniques also are being applied to exercise testing so that the motion of the walls of the ventricles and other physical characteristics of the heart under stress can be studied. A stress echocardiogram is done during or immediately after an exercise stress test, or after the injection of the drug dobutamine, which produces a stress on the heart similar to exercise. Failure of a part of the heart to contract well often indicates that under conditions of stress, part of the heart does not receive enough blood and is supplied by a narrowed coronary artery.
Transesophageal echocardiography is a procedure in which the sonar device is attached to a relatively long, narrow tube and inserted through the mouth and into the esophagus. It is more complicated and slightly riskier than routine transthoracic (across the chest) echocardiography. Transesophageal echocardiography permits physicians to monitor heart function during surgery more closely. It is also used to diagnose vegetations on the heart valves and to detect aortic dissection. It allows better visualization of posterior structures and prosthetic valves that may not be seen on transthoracic echocardiograms.
What is the difference between a transthoracic and a transesophageal echocardiogram?
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