of his profession to apply ultrasonic pulse echo imaging in diagnosing cardiac disease, which the acoustical physicist Floyd Firestone had developed to detect defects in metal castings. In fact, Edler in 1953 produced the first echocardiographs using an industrial Firestone-Sperry Ultrasonic Reflectoscope. In developing echocardiography, Edler worked with the physicist Carl Hellmuth Hertz, the son of the Nobel laureate Gustav Hertz and grandnephew of Heinrich Rudolph Hertz. Medical uses Health societies recommend the use of echocardiography for initial diagnosis when a change in the patient's clinical status occurs and when new data from an echocardiogram would result in the physician changing the patient's care. Health societies do not recommend routine testing when the patient has no change in clinical status or when a physician is unlikely to change care for the patient based on the results of testing. A common example of overuse of echocardiography when not indicated is the use of routine testing in response to a patient diagnosis of mild valvular heart disease. In this case, patients are often asymptomatic for years before the onset of deterioration and the results of the echocardiogram would not result in a change in care without other change in clinical status. Echocardiography now has a vast role in pediatrics, diagnosing patients with valvular heart disease and other congenital abnormalities. An emerging branch is fetal echocardiography, which involves echocardiography of an unborn fetus. Types There are three primary types of echocardiography: transthoracic, transesophageal, and intracardic. Stress testing utilizes tranthoracic echo in combination with an exercise modality (e.g., a treadmill). Intravascular ultrasound is included below, but is as the name indicates more "ultrasound" than "echocardiography" as it is imaging the walls of a vessel rather than the heart. Transthoracic echocardiogram A standard echocardiogram is also known as a transthoracic echocardiogram (TTE) or cardiac ultrasound; and it is used for rapid evaluation of a patient at their bedside. In this case, the echocardiography transducer (or probe) is placed on the chest wall (or thorax) of the subject, and images are taken through the chest wall. This is a non-invasive, highly accurate, and quick assessment of the overall health of the heart. Transesophageal echocardiogram A transesophageal echocardiogram is an alternative way to perform an echocardiogram. A specialized probe containing an ultrasound transducer at its tip is passed into the patient's esophagus, allowing image and Doppler evaluation from a location directly behind the heart. It is most