The purpose of this study is to assess the feasibility of the use of the GORE® TAG® Thoracic Branch Endoprosthesis to treat aneurysms involving the proximal Descending Thoracic Aorta (DTA)

The GORE® TAG® Thoracic Endoprosthesis (TAG® Device) received premarket approval (PMA) for use in endovascular aneurysm repair of the descending thoracic aorta (DTA) on 23-Mar-2005 under P040043, and design changes that resulted in the conformable GORE® TAG® Thoracic Endoprosthesis (CTAG Device) received premarket approval for the treatment of aneurysms of the DTA on 23-Aug-2011 (P040043/S039). The TAG® Device and CTAG Device are intended to exclude an aneurysm from the blood circulation in patients diagnosed with DTA aneurysms. However, endovascular-only treatment options for patients with aneurysms approaching the aortic arch are limited as current stent graft technology would require coverage of the left subclavian artery (LSA) which may result in the need for a surgical revascularization procedure. This prompted the creation of the GORE® TAG® Thoracic Branch Endoprosthesis (previously known as Branched TAG® Device), which was evaluated in this study under IDE G130120 for Zone 2 aneurysms of the DTA.

Inclusion Criteria:

1. Presence of DTA aneurysm deemed to warrant surgical repair which requires proximal graft placement in Zone 2:

   1. Fusiform (≥ 55 mm), or
   2. Fusiform (>2 times native aortic diameter), or
   3. Saccular (no diameter criteria)

2. Age ≥18 years at time of informed consent signature

3. Subject is capable of complying with protocol requirements, including follow-up

4. Informed Consent Form (ICF) is signed by Subject or legal representative

5. Must have appropriate proximal aortic landing zone, defined as:

   1. Must require coverage of the left subclavian artery (LSA) origin for exclusion of the lesion
   2. Aortic inner diameters between 16-48 mm
   3. Landing zone, which must include the LSA ostium, cannot be aneurysmal, heavily calcified, or heavily thrombosed,
   4. Acceptable proximal landing zone outer curvature length for the required device
   5. Landing zone must be native aorta

6. Must have appropriate distal aortic landing zone, defined as:

   1. Outer curvature length must be ≥2cm proximal to the celiac artery
   2. Aortic inner diameters between 16-48mm (diameter should be between 16-42mm if using distal TAG® Device extension)
   3. Landing zone cannot be aneurysmal, heavily calcified, or heavily thrombosed
   4. Native aorta or previously implanted GORE® TAG® Device

7. Must have appropriate LSA landing zone, defined as:

   1. LSA length of ≥3 cm proximal to first major branch vessel if using Aortic Component with 8 mm portal diameter, or LSA length of ≥2.5 cm proximal to first major branch vessel if using Aortic Component with 12 mm portal diameter
   2. LSA inner diameters of 6-15 mm if using Aortic Component with 8 mm portal diameter, or inner diameters of 11-18 mm if using Aortic Component with 12 mm portal diameter
   3. Target branch vessel landing zone cannot be aneurysmal, heavily calcified, or heavily thrombosed

Exclusion Criteria:

1. Concomitant aneurysm/disease of the ascending aorta, aortic arch, or abdominal aorta requiring repair

2. Previous endovascular repair of the ascending aorta

3. Previous endovascular repair of the DTA with a non-Gore device

4. Surgery within 30 days of treatment

5. Infected aorta

6. Dissection of the DTA

7. Intramural hematoma of the DTA without DTA aneurysm

8. Life expectancy <2 years

9. Myocardial infarction or stroke within 6 weeks prior to treatment

10. Patient has a systemic infection and may be at increased risk of endovascular graft infection

11. Pregnant female at time of informed consent signature

12. Degenerative connective tissue disease, e.g. Marfan's or Ehler-Danlos Syndrome

13. Participation in another drug or medical device study within one year of study enrollment

14. Known history of drug abuse within one year of treatment

15. Significant thrombus or atheroma in the aortic arch

16. Tortuous or stenotic iliac and/or femoral arteries preventing introducer sheath insertion and the inability to use a conduit for vascular access

17. Planned coverage of left carotid or celiac arteries

18. Patient has known sensitivities or allergies to the device materials

19. Patient has known hypersensitivity or contraindication to anticoagulants or contrast media, which is not amenable to pre-treatment

20. Previous instance of Heparin Induced Thrombocytopenia type 2 (HIT-2) or known hypersensitivity to heparin

21. Diameter taper outside of the device sizing range between proximal and distal landing zones of aorta and the inability to use additional devices of different diameters to compensate for the taper

22. Mycotic aneurysm

23. Persistent refractory shock (systolic blood pressure <90 mm Hg)

24. Patient has body habitus or other medical condition which prevents adequate visualization of the aorta

    Additionally, the following exclusion criteria apply for Subjects enrolled in Stage 1:

25. Aberrant right subclavian or left vertebral arteries

26. Occluded/stenosed/hypoplastic right vertebral artery

27. Presence of a patent left internal mammary artery (LIMA) graft

28. Bilateral carotid artery disease

29. Known incomplete Circle of Willis

30. Known left vertebral artery ending in posterior inferior cerebellar artery (PICA)