The following inclusion/exclusion criteria was obtained from the study protocol.

INCLUSION CRITERIA

To be eligible for enrollment, a subject must meet all of the following inclusion criteria:

1. Subject is between the age of 18 and 85.
2. Subject must be considered a candidate for elective surgical repair of the TAA (i.e., low-to-moderate risk \[categories 0, 1, and 2\] per the modified SVS/AAVS scoring system at the time of implant). See Appendix B: Modified SVS/AAVS Medical Co-Morbidity Grading System
3. If subject is female of childbearing potential, she must have a negative pregnancy test within 7 days before the implant procedure.
4. Subject has a DTA that is:

1. A fusiform aneurysm with a maximum diameter of ≥ 5 cm OR is \> 2 times the diameter of the non-aneurysmal thoracic aorta;

AND/OR
2. Saccular aneurysm (penetrating atherosclerotic ulcer)
5. Subject's anatomy must meet all of the following anatomical criteria:

1. Subject's TAA must be ≥ 20 mm distal to the origin of the left common carotid artery and must be ≥ 20 mm proximal to the celiac artery;
2. Proximal and distal non-aneurysmal neck diameter measurements must be between 20 mm and 42 mm;
3. Proximal and distal non-aneurysmal neck must be ≥ 20 mm in length.
6. Thoracic aortic lesion is confirmed, at a minimum, by diagnostic contrast enhanced computerized tomography (CT) with optional 3-D reconstruction, and/or contrast enhanced Magnetic Resonance Angiogram obtained within four (4) months prior to the implant procedure.
7. Subject is able and willing to comply with the protocol and undergo follow-up requirements.
8. Subject or subject's legal representative understands and has signed an Informed Consent approved by the Sponsor and by the IRB for this study.
9. Subject has patent iliac or femoral arteries or can tolerate a vascular conduit that allows endovascular access to the aneurysmal site with the delivery system of the appropriate size device chosen for treatment.

EXCLUSION CRITERIA

To be eligible for enrollment, a subject cannot meet any of the following exclusion criteria:

1. Planned placement of the COVERED portion of the stent graft requires implant to occur in zones 0 or 1.
2. Subject has a thoracic aneurysm with a contained rupture.
3. Subject has a connective tissue disease (e.g., Marfan's syndrome, aortic medial degeneration).
4. Subject has a mycotic aneurysm or is suspected of having systemic infection.
5. Subject has received a previous stent or stent graft or previous surgical repair in the DTA.
6. Subject requires treatment of an infra-renal aneurysm at the time of implant.
7. Subject has a history of bleeding diathesis, coagulopathy, or refuses blood transfusion.
8. Subject has had or plans to have a major surgical procedure within 30 days before or after the Valiant Stent Graft procedure. This does not include planned procedures that are needed for the safe and effective placement of the stent graft (i.e., carotid/subclavian transposition, carotid/subclavian bypass procedure).
9. Subject has had an MI or cerebral vascular accident (CVA) within 3 months.
10. Subject is currently participating in an investigational drug or device clinical trial.
11. Subject has a known allergy or intolerance to the device components.
12. Subject has a known hypersensitivity or contraindication to anticoagulants or contrast media, which is not amenable to pre-treatment.
13. Subject has significant and/or circumferential aortic mural thrombus at either the proximal or distal attachment sites that would compromise fixation and seal of the device.
14. Subject has other medical, social, or psychological problems that, in the opinion of the investigator, preclude him or her from receiving this treatment and the procedures and evaluations pre- and post-treatment, or a limited life expectancy of less than 1 year.