Additional Study Information: Has your doctor determined that you have Type B Aortic Dissection and you would like to learn more about an alternative to open surgery? Type B Aortic Dissection patients are being invited to take part in a research study of an investigational device. Bolton Medical, Inc., the company sponsoring this clinical trial, is studying an investigational device called the RelayPro Stent-Graft System. This device is for use in subjects with acute, complicated type B aortic dissection that has either shown up suddenly or has been changing quickly within a 2-week period. Subjects who agree to join this study must sign and date an informed consent form, and undergo the following tests and procedures, unless already performed as per standard of care prior to placement of the RelayPro Stent-Graft System: medical history assessment; physical examination (including neurological functions); CT with contrast (computed tomography), an X-ray type picture of your aneurysm and blood vessels; pregnancy test (serum or urine) for females of child-bearing potential. Subjects medical condition after stent-graft implantation will be closely followed. Subjects will be asked to return to the hospital so the study team can monitor their medical health. After leaving the hospital, subjects will come back to see his/her doctor for standard follow-up visits at 1 month, 6 months, 1 year, and annually for up to 5 years after the implantation of his/her stent-graft. If you have any questions or would like to find more about this research study, its procedures, risks, benefits, or alternative courses of treatment, you should contact Claudia Musat, the Research Manager, at (212) 342-4102.