What Is Transesophageal Echocardiography (TEE)? Transesophageal echocardiography (TEE) is an advanced ultrasound technique used to obtain high-resolution images of the heart and thoracic aorta. Instead of placing the ultrasound probe on the chest, the probe is inserted into the esophagus, which lies directly behind the heart. Because the esophagus sits so close to the heart and the aorta, TEE provides clearer and more detailed images than standard echocardiography in many sit