<unk>  is inherently limited in what it is capable of doing. Notably, it must be used through the skin, and ultrasound waves must go through skin and soft tissue before reaching the heart. This is in contrast to transesophageal echo (TEE) in which the probe is directly behind the left atrium in the esophagus and has far less tissue to penetrate, which means images from TEE are far superior in quality. Extremes in body sizes (obesity and cachexia) limit the acoustic windows and degrade the image quality of<unk> s.<unk>  is also limited in its views of structures. Being a surface modality, the structures closest to the skin are better visualized than those deeper to the skin. A common example that demonstrates this is the visibility of the left atrial appendage. This structure is known to form clots in atrial fibrillation and the LAA is rarely seen on<unk>  but readily seen on TEE. Cardioversion of atrial fibrillation in someone not on anticoagulation would require TEE to best visualize the LAA to rule out a thrombus. (If a thrombus is present, there is a much higher risk of stroke if returned to a sinus rhythm.) Like all of the kinds of<unk> hy,<unk>  is limited to structure and function. It is not, for example, able to determine perfusion of the myocardium, which would require a metabolic imaging modality such as PET or SPECT stress testing. Perfusion can be inferred based on wall motion, however.
Transthoracic echocardiogram
Ballistocardiography
Transesophageal echocardiogram
Magnetocardiography
Phonocardiogram
Impedance cardiography
Doppler echocardiography
Echocardiography