FREQUENCY AND EXPLANATION OF FALSE-NEGATIVE DIAGNOSIS OF AORTIC DISSECTION BY AORTOGRAPHY AND TRANSESOPHAGEAL ECHOCARDIOGRAPHY

Objectives. This study was designed to define the frequency and explan ation of false negative diagnosis of aortic dissection by aortography and transesophageal echocardiography. Background. Aortography and tran sesophageal echocardiography have been widely utilized to diagnose aor tic dissection. Previous reports have not fully addressed the reasons why these studies yield false negative results in a large number of pa tients with aortic dissection. Methods. Sixty-five consecutive patient s with aortic dissection under ent aortography and transesophageal ech ocardiography. Diagnosis of aortic dissection was confirmed at operati on or by computed tomography in all patients. Results. Biplane transes ophageal echocardiograms yielded false negative results in two patient s (sensitivity 97% [63 of 65]). Both patients had well localized DeBak ey type II aortic dissection. The diagnosis was probably missed becaus e of image interference from the air-filled trachea and mainstem bronc hi, In both patients, the dissection was readily identified by aortogr aphy. Aortograms yielded false negative results in 15 patients (sensit ivity 77% [50 of 65]); the aortic dissection was type I in 7 patients, type II in I and type III in 7. The dissection in all 15 patients was readily identified by transesophageal echocardiography. The missed di agnosis was probably due to a completely thrombosed false lumen or int ramural hematoma with noncommunicating dissection in 13 patients and t o a large ascending aortic aneurysm with nearly equal flow on both sid es of the intimal flap in 2. In no patient was the diagnosis missed by both aortography and transesophageal echocardiography. Conclusion. Tr ansesophageal echocardiography is an excellent screening tool for aort ic dissection, However, it may miss small type II aortic dissections l ocalized to the upper portion of the ascending aorta because of image interference from the air-filled trachea. An intramural hematoma canno t be easily visualized by aortography, and this lesion is the principa l reason for false negative aortographic findings.