Differential Transesophageal Echocardiographic Diagnosis Between Linear Artifacts and Intraluminal Flap of Aortic Dissection or Disruption: Results Protocol A

The TEE criteria found to be predictive of the presence of linear artifacts within the descending thoracic aorta are shown in Table 2. Both the thickness of linear artifacts and the angle between the aortic wall and the linear image tended to be larger than those noticed in true aortic flaps (3.3 ± 1.5 mm vs 2.6 ± 1.1 mm, p = 0.08; and 90 ± 14° vs 72 ± 40°, p = 0.1, respectively; Fig 5, top left, A, and bottom left, C). None of the patients with linear artifacts in the descending thoracic aorta had evidence for entry tears. Logistic regression analysis identified the following criteria as predictors of the presence of a linear artifact in the descending thoracic aorta: (1) displacement of the linear image parallel to the aortic walls (odds ratio, 15.9; CI, 1.8 to 142.8; p = 0.01); (2) overimposition of blood flow on the linear image (odds ratio, 6.9; CI, 1.3 to 38.3; p = 0.03); and (3) similar blood flow velocities on both sides of the linear image (odds ratio, 7.6; CI, 1.3 to 43.5; p = 0.02; Fig 5, top right, B, and bottom right, D). canadian family pharmacy

Origin of Linear Artifacts: The diameter of the ascending aorta was larger in patients with linear artifacts (n = 59) when compared to patients without (n = 135) intraluminar artifacts (39.9 ± 12.0 mm vs 33.9 ± 6.2 mm; p < 0.001). In contrast, the mean diameter of the posterior structure (ie, the left atrium or the right pulmonary artery) was larger in patients without linear artifacts (34.3 ± 6.9 mm vs 28.8 ± 6.1 mm; p < 0.001). Consequently, the ratio between the diameter of the ascending aorta and adjacent posterior structure was higher in the presence of linear artifacts (1.4 ± 0.6 vs 1.0 ± 0.2; p < 0.001). In patients with intra-aortic linear artifacts, the mean distance between the transducer or the posterior wall of the right pulmonary artery or the left atrium, and the posterior wall of the ascending aorta was similar to that separating the latter from the leading edge of the intraluminal artifact (28.8 ± 6.1 mm vs 28.6 ± 5.7 mm; p = 0.9, matched t test; Fig 6, top left, A).
The mean diameter of the descending thoracic aorta was similar between patients with linear artifacts (n = 17) and those without intraluminal artifacts (n = 132; 25.2 ± 4.8 mm vs 27.6 ± 8.3 mm; p = 0.8). Conversely, the distance separating the esophageal scope from the anteromedial aortic wall was greater in the presence of a linear artifact within the descending thoracic aorta (6.9 ± 2.7 mm vs 5.2 ± 5.2 mm; p < 0.001; Fig 6, right, B).
TEE Diagnostic Accuracy: The diagnostic accuracy of TEE for the identification of true intra-aortic flap is detailed in Table 3. Three false-negative TEE diagnoses were attributed to the presence of limited dissections involving the descending thoracic aorta or the aortic arch, and one false-negative TEE diagnosis was attributed to the presence of a small traumatic medial tear confined to the aortic isthmus. Two patients underwent unnecessary thoracotomy based on the presence of a linear intraluminal image erroneously diagnosed as an intra-aortic flap. The first patient sustaining a type-B AD also had a dilated ascending aorta (65 mm), but without evidence of proximal dissection (Fig 6, left, A). The second patient was suspected of sustaining a traumatic disruption of the aortic isthmus (Fig 6, right, B), but visual inspection during surgery revealed only the presence of a hemomediastinum with a normal proximal descending thoracic aorta.
Figure 5. Two-dimensional TEE (top left, A; bottom left, C) and color Doppler echocardiographic imaging (top right, B; bottom right, D) of the descending aorta in a patient with an intraluminal linear artifact (top left, A; top right, B), and in a patient sustaining a type-B AD (bottom left, C; bottom right, D), for comparison. The linear artifact (top left, A, arrow) is thicker than the intimal flap associated with the AD (bottom left, C, arrow), near horizontal, and showed displacement parallel the aortic walls in real time. Using color Doppler echocardiographic mapping, blood flow velocities appear similar on both sides of the artifact, laminar, and overimposed on the linear image (top right, B). Conversely, blood flow is not overimposed on the intimal flap of the distal AD, and velocities are higher in the true lumen than in the false lumen (bottom right, D).
Figure 6. Examples of linear artifacts (thick arrows) located within the ascending (left, A) and descending thoracic aorta (right, B) in two patients who underwent unnecessary surgery. The distance between the transducer and the posterior wall of the ascending aorta is identical to that separating the latter from the intra-aortic linear image (double-headed arrows). Note also that the diameter of the dilated ascending aorta exceeds that of the left atrium (left, A). The linear artifact located within the descending thoracic aorta is thick and horizontal. In this patient, the aortic isthmus is anteriorly shifted secondary to the presence of a traumatic hemomediastinum (right, B).
Table 2—Univariate Analysis of TEE Parameters Used To Distinguish Between Intraluminal Linear Artifacts and Flaps of Descending Thoracic Aorta

Variables Artifact (n = 17) Flap (n = 81) Odds Ratio 95% CI p Value
Immobility 10 (59) 15 (19) 6.2 2.0-18.9 0.001
Displacement parallel to aortic walls 16 (94) 24 (30) 37.0 4.7-333.3 < 0.001
Poorly defined borders 9(53) 12 (15) 6.4 2.1-19.6 0.001
Image not confined to aortic lumen 9 (53) 6(7) 13.9 3.9-50.0 < 0.001
Overimposition of blood flow 9(53) 3 (4) 28.9 6.5-128.9 < 0.001
Similar blood flow velocities on both sides 15 (88) 21 (26) 21.3 4.4-100.0 < 0.001
Absence of blood flow turbulence 16 (94) 49 (60) 10.1 1.3-83.3 0.03
Absence of left pleural effusion 15 (88) 64 (79) 1.9 0.4-9.0 0.43
Thickness > 2.5 mm 10 (59) 30 (37) 3.0 0.9-9.7 0.06
Angle > 85° 7(41) 30 (37) 1.2 0.4-3.6 0.72

Table 3—Influence of Systematic Use of TEE Diagnostic Criteria To Distinguish Linear Artifacts From True Intra-aortic Flaps (Protocol B) on Its Diagnostic Accuracy for the Diagnosis of Spontaneous AD and TDA

Variables Sensitivity, % Specificity, % Positive Predictive Value, % Negative Predictive Value, %
Protocol A (n = 230)*
Ascending aorta (range) 97.2-97.2 92.9-99.5 71.4-97.2 99.4-99.5
Descending thoracic aorta (range) 93.8-97.5 93.3-99.3 88.8-98.7 96.7-98.6
Protocol B (n = 121)
Ascending aorta
At least one criterion! 92.9 68.2 65.0 93.8
At least two criteria 92.9 95.5 92.9 95.5
At least three criteria 92.9 100.0 100.0 95.7
All four criteria 42.9 100.0 100.0 73.3
Descending thoracic aorta
At least one criterion{ 97.1 100.0 100.0 87.5
At least two criteria 82.4 100.0 100.0 53.8
All three criteria 64.7 100.0 100.0 36.8