The indications for treatment of abdominal and thoracic aortic aneurysms have evolved over the past 50 years. Current recommendations are to treat patients whose abdominal aortic diameter is greater than 5.5 cm in men and 5 cm in women. Indications for treating patients with thoracic aneurysms are aneurysms reaching 6 cm in diameter, aneurysms that rupture, and rapidly expanding aneurysms with an increase in diameter greater than 0.5 cm over 6 months or 1 cm within 1 year. In addition, relative indications include patients who suffer distal embolism from the aneurysm or who have significant symptomatic concomitant aortoiliac occlusive disease.
When considering repair of an abdominal endovascular aneurysm repair or thoracic endovascular aneurysm repair with an endovascular stent graft, preoperative preparation begins with adequate imaging. Computed tomography scanning or magnetic resonance imaging with fine cuts (1 mm or less) of the entire thoracic and abdominal aorta down through the femoral arteries is mandatory for sizing the endograft. The necessary measurements obtained from the computed tomography scan include proximal aortic neck diameter at the level of the renal arteries and 10 and 15 mm below the renal arteries. In addition, bilateral diameters are obtained of the common iliac, external iliac, internal iliac, and femoral arteries. Other necessary measurements include the length from the renal arteries to the aortic bifurcation and the length of the common iliac arteries.
Patients who have external iliac and femoral arteries that are less than 7 mm in diameter may require an iliac conduit (to deliver the stent grafts). An iliac conduit is necessary to deliver an endograft when the external and/or common iliac arteries are too small to accommodate a large sheath. In this circumstance, an 8- or 10-mm Dacron graft is sewn to the common iliac bifurcation and the common femoral artery, providing a large vessel to deliver the stent graft. This may be necessary for patients with severe occlusive disease or vessel diameters of less than 6–7 mm. In addition, attention to the proximal neck diameter and length is an important consideration for using endovascular repair. In general, a neck length of less than 1 cm and neck diameter of greater than 32 mm preclude endovascular aneurysm repair. Similarly, for thoracic aneurysms, a neck diameter greater than 40 mm and length less than 2 cm preclude thoracic endovascular aneurysm repair. Additionally, for endovascular aneurysm repair, it is recommended that one hypogastric artery be patent or that a hypogastric artery bypass should be considered to minimize pelvic ischemia. Currently, only one device allows for treating iliac aneurysms with a hypogastric branch device.
Anesthesia for endovascular aneurysm repair and thoracic endovascular aneurysm repair can be spinal, general, or local block. However, patients should be prepared for possible open conversion, so routine central venous line access and arterial line access are required. For thoracic endografts, an ...