The primary objective of this single arm, prospective feasibility study, Impact of Frailty on Clinical Outcomes of Patients Treated for Thoracoabdominal and Complex Abdominal Aortic Aneurysms with Physician-Modified Fenestrated and Branched Stent Grafts, is to assess the use of the physician-modified fenestrated/branched endografts to repair thoracoabdominal and complex aortic aneurysms in subjects having appropriate anatomy, at high risks for open repairs. The primary intent of the study is to assess safety and preliminary effectiveness of the device acutely (i.e., treatment success and technical success), at 30 days (i.e., the rate of major adverse events (MAE)) and at 3 months, 6 months, 12 months, and annually to 5 years (i.e., the proportion of treatment group subjects that achieve and maintain treatment success). Additionally, this study will assess the degree of patient frailty before and after the aneurysm repair, as well as the association between the preoperative baseline frailty and clinical outcomes detailed above. This will help improve subject selection in identification of high risk patients who would not only suffer poor clinical outcomes, but also experience decline in their functional status.