Distribution of intimomedial tears in patients with type B aortic dissection

Objective

Thoracic 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.

Methods

Advanced 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.

Results

Each 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.

Conclusions

Characterization 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.