A Transesophageal Echocardiogram (also referred to as a TEE) is a diagnostic test used to view the structures of the beating heart. In this procedure, a transducer is passed through the mouth and into the esophagus, which lies behind the heart. The transducer then sends images of the heart to a monitor. TEE is commonly done in people with atrial fibrillation to see if blood clots have formed in the top chambers of the heart called the “atria”.