Distribution of intimomedial tears in patients with type B aortic dissection

ObjectiveThoracic endovascular aortic repair is a promising means of treating patients with complicated type B aortic dissection by excluding the intimomedial tears. This study aims to characterize the location of tears and to propose a classification of type B aortic dissections based on these findings.MethodsAdvanced protocols in computed tomography scans of patients with type B aortic dissection were used to identify the size and location of intimomedial tears in relation to the origin of the left subclavian artery. Aortic imaging details in 72 un-operated patients were used as a reference standard. From 1999 to 2005, 44 patients underwent primary endovascular treatment for complications of type B aortic dissection.ResultsEach patient had an average of 2.8 ± 2.11 intimomedial tears. The median intimomedial tear surface area was 0.63 cm2. The presence of ≥3 or ≥5 intimomedial tears in the descending thoracic aorta did not correlate with aortic branch malperfusion (P > .05). Thirteen of 26 (50%) patients with a tear >1.9 cm2 had aortic branch malperfusion (P = .032). Ten of 14 (71%) patients with a tear >4.86 cm2 (mean plus one standard deviation) had aortic branch malperfusion (P = .002). The location of tears ranged from -6 mm to +459.2 mm from the left subclavian artery orifice: 80.5% (n = 99) of these tears were above the reference origin of the celiac artery. Eight of 13 patients (62%) with a tear distal to 282 mm (the orifice of the celiac artery) had aortic branch malperfusion in (P = .04). A classification for the location of intimomedial tears is proposed with potential clinical relevance to endovascular repair: type 1 has no identifiable tears; type 2 has one or more tears with no tears distal to the orifice of the celiac artery; type 3 has tears involving the branch vessels of the abdominal aorta; and type 4 has intimomedial tears distal to the aortic bifurcation.ConclusionsCharacterization and location of intimomedial tears using computed tomography (CT) imaging is feasible and represents an important step in the management of type B aortic dissection. The location and surface area of tears is associated with malperfusion. Based on the proposed classification and anatomic reference data, three out of every four patients may have a favorable constellation of intimomedial tears (type 1 or 2) that would be amenable to endovascular repair and reverse aortic remodeling. The clinical correlation will be established in upcoming studies.