The purpose of this research study is to find out if AMDS is safe and effective in the treatment of acute dissection (sudden tear). For patients whose aortic anatomy is suitable for treatment with AMDS, the use of this device may promote healing of the aortic walls and possibly reduce the need for additional aortic surgeries. If conventional surgery, in combination with AMDS, is effective, it is believed that this could lead to improved aortic healing; an improvement in healing could reduce the risk of hospitalization and reoperation in the chest compared to conventional surgery alone.