 This study is a prospective, non-randomized evaluation of ascending and thoracic pathology endovascular repair in the high-risk patient. The purpose of this study is to assess the role of the thoracic aortic pathology treatment using endovascular prosthesis in high-risk patients. The study objectives include 1 to assess the safety and efficacy of endovascular prosthesis as a means of preventing aneurysm growth and rupture in high risk patients, 2 to measure the physiologic effects and outcomes of endovascular aneurysm repair, 3 to establish selection criteria, improve device design, operative technique, and follow-up procedures for patients undergoing aneurysm repair. There will be up to 15 patients in the ascending aortic lesion arm and 20 patients in Arch Branch arm; all at one site The Cleveland Clinic. Baseline procedures may include an angiogram, intravascular ultrasound, CT scan, chest x-ray, physical exam, blood work, and ankle-brachial index. The endovascular prosthesis is placed in the operating room under regional or general anesthesia. Follow-up evaluations may include physical exam, blood work, CT scan or MRI, chest x-ray, cardiac echo and ankle-brachial index. 