There will be a maximum of 100 patients treated with the new device. You will be evaluated by your doctor to determine if you are able to participate in this research study. This evaluation will include reviewing your medical history, a physical examination, and special x-rays. These special x-rays are called CT scans and angiograms. Your doctor will explain what tests you will have done. A CT scan is a special x-ray that allows your doctor to see the size and shape of your aorta and your arteries. An angiogram uses a catheter (a hollow tube) that is placed into your arteries. Both tests use dye that can be seen on x-rays to see how the blood flows through your aorta and the surrounding arteries; for the CT scan it will be injected into a vein, and for the angiogram it is injected through the catheter into your arteries. These tests would be conducted whether or not you were participating in this research study. Your doctor will use this type of testing to determine if you are eligible to participate in this research study and as part of your follow-up care. Currently there are two aortic stent grafts manufactured by W.L. Gore & Associates that are approved by the FDA for experimental use. Your doctor will determine which device is more appropriate to treat your condition.