[Limitations of transesophageal ultrasound in the assessment of intracardiac masses: a case report].

A 72-year-old man who had been treated for 20 years with warfarin for auricular fibrillation was scheduled for resection of a sessile mass (3.5 x 4 cm) on the posterior wall of the left atrium and a smaller mass (1.5 x 2 cm) in the right atrium. The masses were diagnosed by transthoracic ultrasonography and computed tomography. After anesthetic induction, a tube was inserted for transesophageal ultrasound guidance during resection of the masses. During surgery, the presence of a large mass was confirmed on the posterior wall of the left atrium, which was enlarged due to chronic fibrillation. The smaller, mobile, pediculated mass attached to the right free wall of the atrium or to the tricuspid valve was also confirmed. Given these findings and the patient's history, differential diagnosis with either biatrial myxoma or thrombus was considered. After opening both atria, an organized thrombus in the left atrium and a large hypertrophic trabecula in the trabeculated portion of the right atrium was found to be responsible for the misleading ultrasonographic image suggesting masses.