U Clinical Progress Series Clinical Applications of

Standard transthoracic ultrasound examination of the heart has provided increasingly better images since it was clinically introduced approximately 25 years ago. Although two-dimen-sional echocardiography is an established tool in clinical cardiology, the image qualities of conven-tional transthoracic approaches can sometimes be unsatisfactory for various reasons, such as patient obesity, chronic obstructive pulmonary disease, and chest wall changes with age. In these patients, trans-esophageal echocardiography can provide important diagnostic information because chest wall interfer-ence and intrathoracic attenuation are eliminated. Furthermore, the close vicinity of the heart and thoracic aorta to the echocardiographic sensor allow