Diagnosis of ascending aortic dissection by transesophageal echocardiography: Utility of M-mode in recognizing artifacts

Objectives. This study sought to assess the reliability of biplanar transesophageal echocardiography in the diagnosis of ascending aortic dissection and to test the utility of M-mode information in the differential diagnosis of ascending aortic ultrasound artifacts and intimal flap images. Background. Transesophageal echocardiography is a useful technique in the diagnosis of aortic dissection. However, ultrasound artifacts in the ascending aorta are an important limitation. Methods. Transesophageal echocardiography was performed in 132 consecutive patients with clinically suspected aortic dissection. Two-dimensional and M-mode echocardiography and color Doppler were used to diagnose intimal flap and artifact images. Diagnoses were validated either anatomically or with reference techniques. Results. The sensitivity and specificity of transesophageal echocardiography in the diagnosis of ascending aortic dissection were 96.8% and 100%, respectively. Ninety-three artifacts were observed in 56 (55%) of 101 patients without ascending aortic dissection. Two-dimensional echocardiography easily identified 74 artifacts (80%). Color Doppler showed no ascending flow abnormalities in 71% of artifact images. M-mode echocardiography showed three location and mobility artifact patterns related to the posterior wall of the aorta or the right pulmonary artery. In contrast, intimal flap movement showed no relation to the aortic wall movement in 25 cases (83%). Blind analysis of transesophageal echocardiographic study tapes underlined the utility of M-mode in the differential diagnosis. Ranges of sensitivity, specificity and positive predictive value (established by including doubtful results as either positive or negative) improved from 87.1–93.5% to 93.5- to 96.8%, from 85.1–94.1% to 99–100% and from 65.9–81.8% to 96.8–100%, respectively, with the inclusion of M-mode data. Conclusions. Biplanar transesophageal echocardiography permits reliable diagnosis of ascending aortic dissection. Ultrasound artifacts are common, but assessment of the location and mobility of intraluminal images by M-mode echocardiography definitely improves diagnostic accuracy.