numerous measurements are taken to aid in diagnosis and grading of diseases. These normal ranges are not as well defined for TEE and so there is less accepted standards (e.g., left atrial enlargement). Some risks are associated with the procedure, such as esophageal perforation around 1 in 10,000, and adverse reactions to the medication. Specialty medicine professional organizations recommend against using transesophageal echocardiography to detect cardiac sources of embolization after a patient's health care provider has identified a source of embolization and if that person would not change a patient's management as a result of getting more information. Such organizations further recommend that doctors and patients should avoid seeking transesophageal echocardiography only for the sake of protocol-driven testing and to agree to the test only if it is right for the individual patient. Clinical uses In addition to use by cardiologists in outpatient and inpatient settings, TEE can be performed by a cardiac anesthesiologist to evaluate, diagnose, and treat patients in the perioperative period. Most commonly used during open heart procedures, if the patient's status warrants it, TEE can be used in the setting of any operation. TEE is very useful during many cardiac surgical procedures (e.g., mitral valve repair). It is actually an essential monitoring tool during this procedure. It helps to detect and quantify the disease preoperatively as well as to assess the results of surgery immediately after the procedure. If the repair is found to be inadequate, showing significant residual regurgitation, the surgeon can decide whether to go back to cardiopulmonary bypass to try to correct the defect. Aortic dissections are another important condition where TEE is very helpful. TEE can also help the surgeon during the insertion of a catheter for retrograde cardioplegia. Probes TEE probes are similar in style to those used for esophagogastroduodenoscopy except the probe contains an ultrasound crystal rather than a visual camera. The ultrasound crystal images radially to the probe rather than axially (along the probe length) as the heart is not inline with the esophagus, but rather adjacent (anterior) to it. Angle Most TEE probes contain a two-dimensional ultrasound crystal. This permits rotation of the 2-D echo plane without physical movement of the probe. This is often referred to the "angle" and varies between 0° and 180° (flipped image of 0°). For any given position of the probe in the body, different angles permit viewing structures more optimally. The angle