An echocardiogram, often referred to as a cardiac echo or simply an echo, is a sonogram of the heart. (It is not abbreviated as ECG, because that is an abbreviation for an electrocardiogram.) Echocardiography uses standard two-dimensional, three-dimensional, and Doppler ultrasound to create images of the heart. An echocardiogram is a test that uses sound waves to create pictures of the heart. The picture and information it produces is more detailed than a standard x-ray image. An echocardiogram does not expose you to radiation.