What is an echocardiogram?
Echocardiography is a non-invasive way to visualize the heart. It uses ultrasound waves at frequencies of 1-20 MHz, i.e., 1-20 million hertz–cycles per second. (The normal range of frequencies that can be heard by the ear is 5 to 20 thousand hertz).
Ultrasound waves reflect back at levels consistent with the different tissue densities encountered and these reflections are computed into a visible image that can be used for measurements of cardiac anatomy, physiology, and function. There are no known adverse effects from clinical ultrasound.
- M-mode ultrasound: The original ultrasound technology that is now used infrequently to capture details of rapidly moving structures such as valve leaflets.
- 2D Ultrasound: Ultrasound waves are used to provide tomographic (“thin slice”) imaging which is then computed into a visual signal.
- 3D Ultrasound: A three-dimensional presentation of cardiac anatomy which integrates 2D and M-mode echocardiographic information.
- TDE: Tissue Doppler Echocardiography assess myocardial motion with color assignment to show frequency shifts of myocardial velocity, useful in documenting ventricular function and abnormalities such as regurgitation.
Types of Echocardiogram and Their Uses:
- Transthoracic Echo (TTE): Via a transducer on the outside of the chest. This is the standard diagnostic cardiac ultrasound.
- Transesophageal Echo (TEE): Via a transducer placed internally into the esophagus with a tube. This ultrasound complements the TTE by providing excellent vies of the posterior and medial portions of the heart without obstruction from lung or bone: potential cardiac sources of emboli, valves to rule out endocarditis, and to rule out thrombi associated with atrial fibrillation.