Two interrelated problems involving the thoracoabdominal aorta require surgical treatment: thoracoabdominal aortic aneurysms and distal aortic dissection. Although both processes can exist independently, they each serve as risk factors for one another and, therefore, often coexist. Patients with aneurysms caused by medial degeneration (the most common cause of thoracoabdominal aortic aneurysms) are at risk for a superimposed dissection. Similarly, the weakened aortic wall in patients with distal aortic dissection predisposes them to subsequent aneurysmal dilatation; this is the second most common cause of thoracoabdominal aortic aneurysms.

Aortic aneurysms can involve any segment from the aortic valve annulus to the aortic bifurcation. Thoracoabdominal aortic aneurysms generally involve varying portions of both the descending thoracic and abdominal aortic segments, as demonstrated by Crawford's classification based on extent (Figure 1).<sup>11 Crawford E.S., Crawford J.L., Safi H.J. , e al. Thoracoabdominal aortic aneurysms: Preoperative and intraoperative factors determining immediate and long-term results of operation in 605 patients J Vasc Surg 1986 ;  3 : 389  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup> Although extent IV aneurysms—occasionally referred to as total abdominal aortic aneurysms—do not extend above the diaphragm, their repair requires access to the descending thoracic aorta to achieve proximal vascular control, so thoracoabdominal aortic aneurysms are best characterized by involvement of the aorta at the level of the diaphragmatic hiatus and the resulting need to clamp the thoracic aorta during repair. Accurate classification is important because the operative strategies, risks, and results are each dependent on the extent of aortic replacement.

Distal aortic dissection, involving the descending thoracic and thoracoabdominal segments, can occur with (DeBakey type I) or without (DeBakey type III) dissection of the ascending aorta. In both settings, complications related to the distal aorta occasionally require urgent surgical treatment in the acute setting, that is, within 2 weeks of onset. In the chronic phase, progressive dilatation of the involved aorta ultimately warrants repair in approximately one third of patients.

Penetrating aortic ulcer and intramural hemorrhage are two variants of acute aortic dissection that can occur in the thoracoabdominal segment and are usually diagnosed based on their appearance in imaging studies. Penetrating aortic ulcer is related to disruption of an atheromatous plaque; progression of the ulcer through the aortic wall results in dissection or rupture.<sup>34 Movsowitz H.D., Lampert C., Jacobs L.E. , e al. Penetrating atherosclorotic aortic ulcers Am Heart J 1994 ;  128 : 1210  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup> An intramural hemorrhage is a localized collection of blood within the aortic wall in the absence of intimal disruption; progressive accumulation of the hematoma results in dissection along the length of the aorta.<sup>2 Banning A.P., Harris K.M., Braverman A.C. , e al. Aortic intramural hematoma [letter] N Engl J Med 1997 ;  337 : 1476

Cliccare qui per andare alla sezione Riferimenti, 35 Nienaber C.A., von Kodolitsch Y., Petersen B. , e al. Intramural hemorrhage of the thoracic aorta: Diagnostic and therapeutic implications Circulation 1995 ;  92 : 1465

Cliccare qui per andare alla sezione Riferimenti, 40 Robbins R.C., McManus R.P., Mitchell R.S. , e al. Management of patients with intramural hematoma of the thoracic aorta Circulation 1993 ;  88 (part 2) : 1

Cliccare qui per andare alla sezione Riferimenti</sup> Because both variants indicate an impending dissection or rupture, their treatment is identical to that of classic distal aortic dissection: aggressive medical management for uncomplicated lesions and emergent surgery for complicated lesions.<sup>5 Coady M.A., Rizzo J.A., Hammond G.L. , e al. Penetrating ulcer of the thoracic aorta: What is it? How do we recognize it? How do we manage it? J Vasc Surg 1998 ;  27 : 1006  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti, 36 O'Gara P.T., Desanctis R.W. Acute aortic dissection and its variants: Toward a common diagnostic and therapeutic approach Circulation 1995 ;  92 : 1376

Cliccare qui per andare alla sezione Riferimenti</sup>