GORE TAG® Thoracic Endoprosthesis - 45 mm for the Treatment of Aneurysms of the Descending Thoracic Aorta

Inclusion Criteria: 1. Presence of Descending thoracic aortic aneurysm deemed to warrant surgical repair * Fusiform (≥50 mm), or * Saccular (no diameter criteria) 2. All proximal and/or all distal landing zone inner diameters between 37-42 mm * Diameter taper between proximal and distal landing zones and the ability to use devices of different diameters to compensate for the taper must be within device sizing guide specifications 3. Proximal and distal landing zone length greater than 2.0 cm * Landing zone must not be aneurysmal, dissected, heavily calcified, or heavily thrombosed 4. Life expectancy \> 2 years 5. Subject is open surgical candidate defined as: * Able to tolerate thoracotomy * American Society of Anesthesiologists class I-IV (class V excluded) * New York Heart Association class I-III or not applicable (class IV excluded) 6. Male or infertile female 7. Age greater than 21 years 8. Able to comply with study protocol requirements, including follow-up Exclusion Criteria: 1. Mycotic aneurysm 2. Hemodynamically unstable aneurysm rupture 3. Aortic dissection 4. Planned occlusion of left carotid or celiac arteries 5. Planned concomitant surgical procedure (other than left subclavian transposition), or major surgery within 30 days of treatment date 6. Myocardial infarction or stroke within 6 weeks of treatment 7. Pre-treatment creatinine \> 2.0 mg/dL 8. Degenerative connective tissue disease, e.g. Marfan's or Ehler-Danlos Syndrome 9. Participation in another drug or device study within 1 year of treatment 10. History of drug abuse within 6 months of treatment