Traditionally, all echocardiographic measurements have been studied utilizing TTE. Therefore the normal values and ranges for pathology findings have been defined by transthoracic means alone. TEE offers different images planes when compared to TTE, which may make the measurements obtained differ from those obtained by TTE. In the operating room environment the vast majority of echocardiography is completed by transesophageal means for many reasons; largely access to the patient and the continuous use of TEE as a hemodynamic monitor. However, given the fact that most echocardiographic measurements have only been validated by TTE, there remains a question as to the validity or precision of TEE-derived measurements.