Transesophageal echocardiographic diagnosis of thoracic aortic dissection with the completely thrombosed false lumen: differentiation from true aortic aneurysm with mural thrombus.

The conventional criteria of aortic dissection with a completely thrombosed false lumen by transesophageal echocardiography is separation of the intima from the layer of thrombus; however, it is not always easy to distinguish from true aortic aneurysm with mural thrombus. Thus we proposed a new transesophageal echocardiographic diagnostic criteria. Seventeen operative patients with suspected subacute or chronic thoracic aortic dissection in whom it was difficult to exclude true aortic aneurysm with mural thrombus underwent transesophageal echocardiography. In thoracic aortic dissection with in completely thrombosed false lumen, the inner lesion surface composed of intima may be smooth and crescent-shaped thrombus may appear inside the wall surface. Therefore our criteria were on the basis of any two of the following: (1) high-echogenic lesion surface, suggesting intima, over the thrombus, (2) smooth lesion surface, and (3) crescent-shaped thrombus. Imaging data were referenced to intraoperative findings. According to the present criteria only two out of 17 patients were misdiagnosed, whereas according to the conventional criteria six patients were misdiagnosed. The sensitivity was significantly higher than when the conventional criteria were used (90% versus 40%; p < 0.05), whereas the specificity was similar. We conclude that the present transesophageal echocardiographic criteria for detection of thoracic aortic dissection with a completely thrombosed false lumen is clinically useful.