As everyone knows, a real heart does not look like the ones we see on Valentine’s Day cards. But how do doctors determine the precise shape of a person’s heart? What’s more, how can they get a glimpse of that heart at work? One of the most common methods is echocardiography.
Echocardiography is based on techniques used by submarine navigators during World War II, who beamed sound waves to detect the presence of enemy subs and undersea obstacles. The practice was based on the principle that when a sound wave passing through water strikes an object, part of the wave is reflected back. By measuring reflected sound waves, not only the presence but also the distance of another submarine could be determined. In the same way, “enemies” within the heart—diseased heart valves, structural defects or enlarged chambers—can be detected by echocardiography.
First, a thin layer of a special gel is applied to the patient’s chest to help conduct the sound waves. A transducer (similar to a microphone) is held firmly against the skin and moved to various spots on the chest, all the while emitting short bursts of high-frequency sound waves. These ultrasound waves, which are beyond the range of human hearing, are directed toward the heart and reflected back. The reflected waves, or echoes, return to the probe and are analyzed by a computer. The computer then converts the information into two-dimensional images, displayed on a monitor, representing the cardiac anatomy.
The key advantage in echocardiography is that the procedure is noninvasive, meaning that no exploratory tubes or incisions are involved. “Echo” is risk free and without known side effects, although the pressure of the hard transducer on the chest may be temporarily uncomfortable. From time to time, it may be necessary to change positions according to the technician’s directions. Following the test, which takes about half an hour and is usually done on an outpatient basis, the patient immediately can return to other activities.
A variation of echocardiography called Doppler ultrasound is now being widely used to measure the velocity of blood flow in major veins and arteries of the arms, legs and head. Echocardiography also can be done during exercise, which provides a better picture of the state of the coronary arteries than an “echo” done at rest.