MBA Early Feasibility Study

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