Protocol A: Two experienced observers blinded to both the clinical history and final diagnosis jointly reviewed the TEE studies. In each patient, the ascending and descending segments of the thoracic aorta were evaluated separately. The observers determined whether a persistent linear intra-aortic image was present or absent, using adequate gain settings. Accordingly, nonlinear artifacts such as mirror images and reflection or comet tail artifacts were not studied, because they usually do not resemble intra-aortic flaps. Each linear intravascular image was then described using the following qualitative and quantitative parameters.
Qualitative two-dimensional TEE parameters included the following: (1) mobility; (2) if mobile, the type of displacement (ie, free or parallel displacement to the aortic wall); (3) sharpness of the image borders; (4) image confined to the aortic lumen or extending outside the aortic wall; (5) presence of a pericardial effusion; and (6) presence of a left pleural effusion. Additional qualitative parameters were obtained from the color Doppler echocardiographic flow mapping of the thoracic aorta and aortic valve: (7) overimposition of blood flow on the linear image, or not; (8) different or similar blood flow velocities on both sides of the intra-aortic image; (9) presence of blood flow turbulence as reflected by a mosaic of colors surrounding the linear image, or normal laminar blood flow pattern; (10) presence of an entry or a reentry tear defined as the presence of blood flow through a typical communication of the linear image, or not; and (11) presence of more-than-mild aortic regurgitation.
Quantitative parameters were then measured independently by a third experienced observer who did not have access to the clinical charts and was unaware of qualitative data recordings. All measurements were performed at end-diastole (identified by the peak R wave of the ECG) in the transverse view, using electronic calipers. The following measurements were performed at the level of the ascending aorta: (1) diameter of the aorta obtained immediately above the sinuses of Valsalva; (2) diameter of the anatomic structure located posteriorly, ie, the left atrium or the right pulmonary artery according to the level of the tomographic plane (Fig 1, left, A); and (3) in the presence of an intra-aortic linear image, the distance between the transducer (or the posterior wall of the left atrium or right pulmonary artery) and the posterior wall of the ascending aorta, and the distance separating the latter from the leading edge of this linear image in the same tomographic plane, along an axis perpendicular to the ascending aorta (Fig 1, center, B). The ratio between the diameter of the ascending aorta and the adjacent posterior anatomic structure was calculated. The following measurements were performed at the level of the descending thoracic aorta: (1) diameter of the aorta at the level of the aortic isthmus, (2) and distance between the esophageal scope and the anteromedial descending aortic wall. Finally, when an intra-aortic linear image was observed, the maximal thickness of this image as well as the angle between the image and the vertical axis tangential to the aortic wall were measured (Fig 1, right, C).
After this analysis was completed, the results of the reference imaging technique were disclosed to the investigators. In each patient, the ascending and descending thoracic aortic segments were classified into one of the following categories: (1) aortic flap. defined as the presence of a linear image noted during the TEE study represented a true intimal flap of AD or a medial flap of TDA; (2) linear artifact, the presence of a linear intra-aortic image not confirmed by the reference technique in the corresponding aortic segment; or (3) absence of linear image, when both the TEE examination and reference diagnostic modality were negative for the presence of an abnormal linear intra-aortic image. In the latter case, the thoracic aorta might have appeared normal or not, but aortic lesions were not associated with an intraluminal flap (eg, intramural hematoma, traumatic intimal tear, aortic aneurysm, atherosclerosis). The diagnostic accuracy of TEE (ie, sensitivity, specificity, positive and negative predicting values) for the identification of aortic flaps was then determined, based on the initial interpretation performed at the time of the TEE study.
Figure 1. Transesophageal transverse view of the ascending (left, A; center, B) and the descending thoracic aorta (right, C). In all patients, the diameter of both the left atrium (LA) and the ascending aorta (AA) was measured (left, A). In the presence of an intra-aortic linear image, the following measurements were also performed: the distance separating the transducer or the posterior wall of the anatomic structure located posteriorly from the ascending aorta (ie, the left atrium or the right pulmonary artery); the distance between the posterior aortic wall to the leading edge of the linear image (center, B, arrow); the angle between the linear image and the vertical axis tangential to the aortic wall (right, C). RV = right ventricle; LV = left ventricle; SVC = superior vena cava; PA = right pulmonary artery; Ao = descending thoracic aorta.