The purpose of this study was to determine whether the pressure produced by contact between a transesophageal echocardiography (TEE) probe and the esophagus was sufficient to cause esophageal damage. The authors studied the effects of sustained contact and associated surface pressure on the esophagus by a TEE probe in anesthetized dogs and humans. Contact pressure between the tip of the probe and the esophageal wall in dogs was measured using a previously described flat balloon of Silastic fitted to the end of a TEE probe and the recording system calibrated with a mercury manometer. In the dog studies, the probe was inserted, maximally flexed, and its position fixed for 4, 6, 8, and 12 h. The maximum surface pressure generated by contact between a probe and the esophageal wall was 10 mmHg. Subsequent pathologic studies failed to reveal either gross or microscopic evidence of tissue damage.The same system was used in short-term patient studies with the surface contact pressure transducer connected to a Camino Catheter 420 Digital Pressure Monitor. In five of six patients contact pressure was <17 mmHg despite maximal rotation of the TEE controls. However, one of the six patients developed very high contact pressure, up to 60 mmHg, between the probe and the esophagus. This patient had no history of esophageal disease but did have intrathoracic pathology.The authors conclude that the maximum surface contact pressure between the esophagus and a fully flexed TEE probe is low in dogs and in most humans, and is unassociated with histologic esophageal damage even with long exposure. However, potentially dangerous pressure may be generated in some cases in humans. It is suggested that the TEE probe not be fixed in a flexed position for prolonged periods since a subset of patients may exist who are at risk for development of high contact pressure and potential esophageal damage.