The MBA 25-04 study is a prospective, multicenter, non-randomized, single-arm, early feasibility study designed to assess the initial safety of the MBA device through five years following the index endovascular procedure.

This study is a prospective, multicenter, non-randomized, single-arm, early feasibility study designed to collect outcomes for subjects treated with the MBA device through five years following the index endovascular procedure. Due to the early feasibility phase of the study, this study utilizes a non-randomized single-arm design with descriptive outcomes, with the primary objective of providing initial safety data.

A maximum of 14 clinical investigative sites in the U.S. and Europe will participate in this study, with up to 12 sites located in the U.S., and up to 2 sites located in Europe.

Enrollment will be conducted in two sequential phases:

• Phase 1: Initial Enrollment

  o The first five implanted subjects will be Dissection pathology (including residual Type A dissections, uncomplicated and high-risk chronic Type B dissections).

• Phase 2: Expanded Enrollment o Following completion of the Initial Enrollment phase, eligibility will broaden to include all planned pathologies: Dissection, Aneurysm, and Other Isolated Lesion (i.e., pseudoaneurysm, PAU without IMH).

Enrollment will continue until a minimum of five Dissection subjects, and a minimum of five Aneurysm / Other Isolated Lesion subjects have been implanted, with a total of 10-20 implanted subjects across all eligible pathologies. A maximum of 15 subjects will be implanted at U.S. sites and a maximum of five will be implanted at European sites

Inclusion Criteria:

The subject is / has:

1. Thoracic pathologies with involvement of the arch branch vessels, that are compatible with the treatment requirements of the MBA device, and meeting any of the following criteria:

   a) Aneurysm and Isolated Lesions: i. Fusiform aneurysm (≥ 55 mm or documented growth rate > 0.5 cm/year). ii. Saccular aneurysm (no diameter criteria). iii. Pseudoaneurysms (> 30 days post-surgery, no diameter criteria). iv. Penetrating Aortic Ulcers (PAUs) without intramural hematoma (IMH) (no diameter criteria).

   b) Aortic dissection: i. Uncomplicated and high-risk chronic de novo (> 90 days) Type B aortic dissection with primary entry tear in the arch or descending thoracic aorta.

   ii. Residual aortic dissection following surgical repair of Type A aortic dissection requiring treatment (> 30 days post-treatment).

   iii. Proximal extension of prior endovascular repair (> 30 days post-treatment and > 90 days post-dissection) of a Type B dissection requiring treatment.

   iv. Pseudoaneurysms, following open surgical repair of a Type A dissection (> 30 days post-surgery, no diameter criteria).

2. Anatomic compatibility with MBA device and other devices required for proximal or distal extensions based on Gore's review.

   1. Adequate vascular access via transfemoral or retroperitoneal approach.
   2. Appropriate vascular access to allow for through-wire access to the brachiocephalic artery, LCCA, and LSA.
   3. Proximal Aortic Landing Zone:

   i. Landing zone is native aorta, surgical graft, or previously implanted GORE thoracic stent graft.

ii. Landing zone diameter between 27 mm - 48 mm. iii. Acceptable ascending aorta outer curvature length for the required MBA device.

1. Proximal segment length (length from distal edge of brachiocephalic artery to distal edge of the most distal coronary artery) must be ≥ 2 cm longer than the "AC Proximal End to BCA Portal Length" for the selected Aortic Component or ≥ 3 cm if the landing zone is > 42 mm.
2. For patients with patent bypass graft from the ascending aorta, proximal extent of landing zone must be ≥ 1 cm distal to the bypass graft.

iv. Lesion location is ≥ 2 cm distal to the most distal coronary artery ostium. v. For patients with an existing transcatheter aortic valve replacement (TAVR) there must be a sufficient proximal landing zone to avoid interference with the required MBA device (including any proximal extensions with the ASG device).

vi. Proximal landing zone must be ≥ 2 cm in the ascending aorta.

1. For patients with prior replacement of the ascending aorta and / or aortic arch by surgical graft, there must be ≥ 2 cm overlap of MBA device and previously implanted graft.

2. For patients with a de novo aortic dissection, the primary entry tear must be located ≥ 2 cm distal to the proximal extent of the MBA device (including any proximal extensions) and the proximal edge of the stent graft must land in non-dissected aorta.

   vii. Landing zone cannot be aneurysmal, heavily calcified, or heavily thrombosed.

   d) Branch Vessel Landing Zone: i. Length of ≥ 2.5 cm proximal to first major branch vessel. ii. Target branch vessel inner diameter of 11-18 mm for the 12 mm portal, and 6-15 mm for the 8 mm portal.

   iii. Target branch vessel landing zone must be in native aorta that cannot be heavily calcified, or heavily thrombosed.

   iv. All three arch target vessels must have appropriate anatomy for cannulation (including through-wire access) and treatment with MBA branch components.

   e) Distal Aortic Landing Zone (aneurysms and isolated lesions only): i. Outer curvature length must be ≥ 2 cm proximal to the celiac artery. ii. Aortic inner diameters between 16-42 mm. iii. Landing zone cannot be aneurysmal, heavily calcified, or heavily thrombosed.

   iv. Landing zone in native aorta, surgical graft, or previously implanted GORE thoracic stent graft.

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

4. Informed Consent Form (ICF) signed by the subject or legally authorized representative (LAR), according to local regulation.

5. Agrees to comply with protocol requirements, including imaging and five year (60 month) follow-up.

6. Considered high-risk for open surgical repair by meeting one or more of the following criteria:

   1. ≥ 75 years of age
   2. Previous median sternotomy
   3. Documented identification of other subject-specific risk factors (e.g., medical history, active medical diagnosis) by a study investigator and an experienced open ascending and / or aortic arch surgeon (e.g., cardiothoracic surgeon).

7. Considered high-risk for surgical debranching by meeting one or more of the following criteria:

   1. Prior neck surgery or radiation
   2. Neck anatomy / body habitus impeding carotid access or safe bypass tunneling
   3. Dysphagia
   4. Elevated risk for post-operative infection (e.g., malnutrition, uncontrolled diabetes (hemoglobin A1c > 9%), current treatment with immunosuppressant therapy or chemotherapy)
   5. Reduced pulmonary function (e.g., severe chronic obstructive pulmonary disease (COPD), current or anticipated tracheostomy)
   6. Clinical Frailty Scale score 6-7
   7. Documented identification of other subject-specific risk factors which would pose high risk for surgical debranching (e.g., medical history, active medical diagnosis) by a study investigator

Exclusion Criteria:

The subject is / has:

1. De novo Type A dissection
2. Requires immediate treatment.
3. Arch vessels with dissection extending into the intended landing zones.
4. Anticipated need for coronary or aortic valve intervention within one year post-treatment.
5. Any aortic valve repair or replacement including transcatheter aortic valve replacement (TAVR) or coronary artery intervention within 30 days prior to treatment.
6. Complex percutaneous coronary intervention (PCI) within 30 days prior to treatment.
7. Open chest surgical repair within 30 days prior to treatment.
8. Any open or interventional repair of either carotid artery within 30 days prior to treatment.
9. Presence of Intramural Hematoma (IMH) in landing zones.
10. Prosthetic heart valve in the aortic position that precludes safe delivery of any study device.
11. Aortic insufficiency (AI) grade 3 or greater.
12. Previous endovascular repair with a non-Gore device that would interfere with or result in contact with planned repair.
13. Concomitant vascular disease, including disease associated with the great and upper extremity vessels, requiring treatment that is not planned for index endovascular procedure.
14. Any stroke or MI within 90 days prior to treatment.
15. Presence of protruding and / or irregular thrombus and / or atheroma in the ascending aorta or aortic arch or any other factor that could increase the risk of stroke based on Gore's review.
16. Any chronic condition that is not well controlled and that is known to increase stroke risk.
17. Known degenerative connective tissue disease (e.g., Marfan's or Ehler-Danlos Syndrome (EDS)).
18. Participation in investigational drug or medical device study within one year of enrollment unless approved by the sponsor.
19. Known medical, social, or psychological issues that the Investigator believes may interfere with treatment or follow-up, such as a history of drug abuse within one year of treatment.
20. Pregnant at time of procedure or planning to become pregnant within the first 12-months of participation in the study.
21. Active infected aorta, mycotic aneurysm.
22. Active systemic infection (e.g., infection requiring treatment with parenteral anti-infective medication).
23. Renal failure, defined as patients with an estimated Glomerular Filtration Rate (eGFR) < 30 (mL/min/1.73 m2) or currently requiring dialysis.
24. Life expectancy <12 months.
25. Known sensitivities or allergies to the device materials.
26. Known hypersensitivity or contraindication to anticoagulants or contrast media, which is not amenable to pre-treatment.
27. Body habitus or other medical condition which prevents adequate fluoroscopic and CT visualization of the aorta.
28. Previous instance of Heparin Induced Thrombocytopenia type 2 (HIT-2) or known hypersensitivity to heparin or a history of a hypercoagulability disorder and / or state.
29. Severe Congestive Heart Failure (CHF) (New York Heart Association (NYHA) functional class IV).
30. Acute Coronary Syndrome (ACS) including unstable angina.