• A patient may be entered into the study if the patient has at least one of the following:

‣ an aneurysm with a maximum diameter of \> 5.5 cm or 2 times the normal diameter just proximal to the aneurysm using orthogonal (i.e., perpendicular to the centerline) measurements

⁃ aneurysm with a history of growth \> 0.5 cm in 6 months

⁃ saccular aneurysm deemed at significant risk for rupture

⁃ symptomatic aneurysm greater than 4.5 cm

• Axillary or brachial and iliac or femoral access vessel morphology that is compatible with vascular access techniques, devices or accessories, with or without use of a surgical conduit.

• Proximal landing zone for the thoracic bifurcation stent graft that has:

‣ ≥ 2.5 cm of nonaneurysmal aortic segment including previously placed graft material (neck) distal to the left subclavian artery (LSA) diameter in the range of 26-42 mm.

⁃ adequate distance from the celiac artery, in order to accommodate cannulation from the antegrade access point when considering the total deployed length of the thoracic bifurcation and visceral manifold.

• Minimum branch vessel diameter ≥ 5 mm.

• Iliac artery or aortic distal fixation site, including both native tissue and previously placed graft, greater than or equal to 15 mm in length and diameter in the range of 8 - 25 mm.

• Patient is ≥ 18 years of age.

• Patient has a life expectancy \> 1 year.

• Patient that meets the criteria for inclusion in the primary study arm but has one or more of the following criteria which would exclude them from the primary study arm:

‣ Patient has a minimum branch vessel diameter less than 5 mm.

⁃ Patients presents urgently or emergently.

⁃ Patient has a contained rupture.

⁃ Patient has a ruptured aneurysm.

⁃ Patient has a type B dissection (subacute or chronic) in the portion of the aorta intended to be treated.

⁃ Patient has poor performance status including two major system failures (cardiovascular, pulmonary, renal, hepatobiliary, and neuromuscular).

⁃ Patient's baseline creatinine greater than 2.0 mg/dL.

⁃ Patient's anatomy that would not allow for maintenance of at least one hypogastric artery.

⁃ Patient's anatomy that would not allow for primary or assisted patency of the left subclavian artery.

• Or

• Patient that meets the criteria for inclusion in the primary study arm and:

‣ Would not be eligible for the primary study arm per a documented reason other than those outlined above, and

⁃ Per the opinion of the Principal Investigator, with concurrence of the IRB, alternative therapies are unsatisfactory and the probable risk of using the investigational device is no greater than the probable risk from the disease or condition.