Transesophageal echocardiography.

ABSTRACT

TEE is the most recent and significant addition to the already existent array of cardiovascular ultrasound imaging techniques. Never before have cardiologists reaped so many benefits from their exploitation of the close anatomic relationship between the heart and esophagus, and never before has there been such a close co-operation and imparting of expertise between gastroenterologists and cardiologist. TEE consists of two-dimensional cardiac and vascular imaging via the esophagus by a flexible echoscope which contains a phased-array mono- or biplane transducer (5MHz) mounted on its distal end. It completely bypasses the transthoracic acoustic impedance and thereby provides superior resolution. TEE requires training of a cardiologist by a gastroenterologist in safe insertion and handling of the echoscope necessary for imaging. The indications and contraindications of TEE have been quickly defined in view of the past TTE and upper gastrointestinal endoscopic experience (ref. Tables 1 and 2). Our own and others experience indicate that only 8%-10% of the indicated TTE studies require supplementary TEE studies either because of inadequate or nondiagnostic TTE imaging for various technical reasons -- e.g., obesity, hyperinflation of lungs, thoracic age abnormalities such as severe pectus excavatum or kyphoscoliosis-or difficult areas of imaging such as left atrial appendage or interatrial septum in the sinus venosus region, aortic dissection, prosthetic valve dysfunction, valvular vegetation, complex congenital heart disease etc. One area in which TEE has made a significant impact is in the intraoperative and perioperative cardiac monitoring for left ventricular function during CABG, repair of intracardiac shunt, cardiac valve repair or replacement and complete removal of intracardiac air before discontinuation of cardiopulmonary bypass. In these contexts, TEE has also proved more practical, convenient and superior to TTE. TEE has also improved the imaging and problem solving in critical care units, particularly in those patients who have recently undergone cardiothoracic surgery and those who are on mechanical ventilation, traditionally the two clinical situations where TTE provides suboptimal results. TEE can safely be performed at the patient's bedside in these units. Refinement and miniaturizing of the transesophageal echoscope (5MHz, small, 6 to 8-mm circumference) has made it possible to perform TEE in infants and young children and improve the diagnosis and surgical management of both cyanotic and acyanotic congenital heart disease.(ABSTRACT TRUNCATED AT 400 WORDS)