Echocardiography is a diagnostic test that uses ultrasound, or high-frequency sound waves, to create images of the heart. A transducer, or modified microphone, turns electrical energy into sound waves, which bounce off tissues in the heart and are recorded onto videotape or computer for later analysis. Echocardiography is primarily used to detect and assess the following: blocked coronary arteries; heart failure or cardiomyopathy (enlargement of the heart); congenital (present at birth) heart defects; damage from hypertension (high blood pressure); heart attack damage or scarring; pericardial disease (the membrane that surrounds the heart); and the function of the heart muscle, blood vessels, and valves.