Clinical significance and origin of artifacts in transesophageal echocardiography of the thoracic aorta.

OBJECTIVES: The aim of this study was to identify the mechanism and features of artifacts encountered during transesophageal echocardiography of the aorta. BACKGROUND: Artifacts are an important potential limitation of transesophageal echocardiography of the aorta. METHODS: The mechanism of the artifacts was examined by in vitro modeling. The frequency and clinical correlates of artifacts were examined by retrospective review of transesophageal echocardiograms in 36 patients with aortic pathologic lesions. RESULTS: Two classes of artifact were seen: linear artifacts in the ascending aorta, which may mimic intimal flaps, and mirror image artifacts in the transverse and descending thoracic aorta. Linear artifacts in the ascending aorta, seen in 44% of patients, were shown in vitro to be multiple path artifacts caused by reflection of ultrasound within the left atrium. Linear artifacts in the ascending aorta were associated with dilatation of the ascending aorta and were more frequent when the aortic diameter exceeded the left atrial diameter (p < 0.001). The mirror image artifacts of the transverse and descending thoracic aorta give the appearance of a double-barrel aorta and were shown in vitro to be caused by the aorta-lung interface, which acts as a total reflector of ultrasound. Mirror image artifacts were seen in > 80% of patients. Artifacts were equally frequent with the sagittal and transverse imaging planes when biplane transesophageal echocardiography was used. CONCLUSIONS: Artifacts occur frequently during transesophageal echocardiography of the aorta. An understanding of why they occur and the features that distinguish them from true abnormalities should enhance the diagnostic accuracy of transesophageal echocardiography for aortic disease.