Figure 52-15 The DeBakey classification of dissecting aneurysms of the aorta. Type I has an intimal tear in the ascending aorta with dissection extending down the entire aorta. Type II has an intimal tear in the ascending aorta with dissection limited to the ascending aorta. Type III has an intimal tear in the proximal descending thoracic aorta with dissection limited to the thoracic aorta (type IIIA) or extending distally to the abdominal aorta or aortoilic bifurcation (type IIIB). (Adapted from DeBakey ME, Beall AC Jr, Cooley DA, et al: Dissecting aneurysms of the aorta. Surg Clin North Am 46:1045–1055, 1966.)