الفهرس 
Anatomy and histology of the aorta 6Only 14 pages are availabe for public view
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Abstract
Aortic aneurysms can develop anywhere along the length of the aorta, but 3/4 are located in the abdominal aorta. Thoracic aortic aneurysms, including those that extend from the descending thoracic aorta into the upper abdomen (thoracoabdominal aneurysms), account for 1/4 of aortic aneurysms (Roselli EE, et al. 2007).
Management of patients with thoracoabdominal aneurysm (TAAA) remains challenging task as it involves replacement of the aorta in those areas where major arterial branches supply vital organs. Hemorrhagic shock, cardiac arrest and multisystem organ failures are the most frequent causes of death, and paraplegia and renal failure are the most devastating complications (Gloviczki, 2002).
Since the first endoluminal approach was de¬scribed by Dotter and Judlkins in 1964, significant advances have been made in the field of vascular disease. Parodi and associates in 1991 reported the first successful clinical endovascular graft repair of an aortic aneurysm (the infrarenal abdominal aorta) in Argentina. Subsequently, endovascular grafts have been used to treat a variety of arterial pathologies, including abdominal aortic aneurysms, thoracic aortic aneurysms, iliac artery aneurysms, occlusive disease, and traumatic lesions, with prom¬ising short- term and mid-term results (Ohki and Veith. 2000). Successful endovascular balloon fenestration of a dissecting descending aortic membrane also was performed to treat mesenteric ischemia (Williams, et al. 1990). Endovascular stent-graft placement as a minimally invasive and potentially safer treatment for aneurysms of the descending aorta was introduced in 1992. In 1994, Dake and associates evaluated the feasibility of a transluminal stent-graft placement to treat descending thoracic aortic aneurysms. The placement of stent-graft prostheses was successful. Despite the less invasive nature of the procedure and the quicker recupera¬tion of the patient, reports of stent-graft use to exclude descending thoracic aortic aneurysms have been limited to a few case series and to isolated cases (Gowda, et al. 2003).
Current indications for endovascular treatment of TAAA are identical to those for open repair, i.e. intractable Pain, evidence of leak or impending rupture, and progressive dilation on serial CT scans. In addition appropriate anatomy is required for endovascular repair which includes the following: (i) adequate iliac/femoral access; (ii) aortic inner diameter in the range of 23mm - 27mm; (iii) normal arterial segment proximal to the aneurysm and distal to the left common carotid artery of at least 2cm in length and less than 38mm in diameter, and (iv) at least 2cm non-aneurysmal aorta distal to the aneurysm (Coselli and Moreno. 2003).
The endovascular exclusion technique is nowadays regarded with favour for this type of aneurysm because it is less invasive and only a short time for aortic occlusion is required (a few minutes versus 20 to 30 minutes of aortic cross-clamping during the open surgery procedure). Nevertheless, the efficacy and feasibility of revascularization of visceral vessels via endovascular exclusion are not sufficiently demonstrated, and the technical difficulties of preserving blood flow in branch vessels (stent insertion and/or fenestration) make this procedure suitable only in a few cases (Stanley, et al. 2001).