Ultrasound, also known as sonography, uses high-frequency sound waves to gather real-time images within the body. It is a safe and painless way of examining internal organs such as the heart, liver, kidneys and bladder, as well as showing movement of internal tissues and organs. Physicians can see blood flow and heart valve functions which can help to diagnose and monitor a variety of heart conditions. No ionizing radiation (x-ray) is used in ultrasound imaging.