By Transesophageal Echocardiography Acoustic Window

Background: The main structures anterior to the trachea are frequently poorly visualized by transesophageal echocardiography (TEE) because of the tracheal air column. The three main branches of the aortic arch and its proximal part have not been visualized successfully by TEE, which was regarded as "blind spots" of TEE. We studied a new acoustic window for TEE imaging of large vessels anterior to the trachea by using a saline-filled endotracheal balloon.Patients, material and Methods'. TEE was performed on 20 patients who underwent cardiac surgery. A multiplanar array probe (Model 21396A) and an ultrasound system (Hewlett-Packard Sonos 4500, Andover, MA) were used in this study. The endotracheal balloon was made with the shaft of a Univent? blocker and part of a latex surgical glove.After ventilation was discontinued at the beginning of cardiopulmonary bypass (CPB), a saline-filled latex balloon was inserted into the trachea through the endotracheal tube. The structures anterior to the trachea were imaged with and without the endotracheal balloon. TEE images of the proximal aortic arch and innominate artery (INA) were classified into 3 grades according to the quality of images: 1, vessel not visible; 2, part of vessel wall visible; 3, entire vessel wall visible. Grade 3 was categorized as good visualization while grades 1 and 2 were categorized as inadequate. TEE images with and without the endotracheal balloon were compared using Mann Whitney U test and Chi Square analysis. P＜0.05 was considered statistically...