FIGURE 10. Classification of Thoracoabdominal Aortic Aneurysms.

The classification of thoracoabdominal aortic aneurysms according to extent of aortic involvement as originally proposed by Crawford is as follows³: Extent I, below the left subclavian to above the celiac axis or opposite the superior mesenteric and above the renal arteries; Extent II, below the left subclavian and including the infrarenal abdominal aorta to the level of the aortic bifurcation; Extent III, below T6 intercostal space, tapering to just above the infrarenal abdominal aorta to the iliac bifurcation; and Extent IV, below T12, tapering to above the iliac bifurcation. Safi et al¹ proposed expanding the classification with the addition of Extent V, below T6, tapering to just above the renal arteries.