Some not too uncommon complications of Type B (distal) aortic dissection:

• Malperfusion syndrome-occurs when the dissection flap occludes a major vessel (e.g. SMA occlusion leading to bowel infarction)
• Occlusion of the spinal arteries and lower extremity arteries can lead to fleeting signs and symptoms-one minute they have left leg pain and ischemia, the next minute they don't. This is pretty classic for acute, distal aortic dissection. 
• Frank rupture (dissected aortic wall is weak and prone to aneurysm formation and subsequent rupture)
• Assume that rupture has occurred (may be intrathoracic or intrabdominal) in a Type B patient who crashes unexpectedly
• Retrograde extension into the proximal aorta is not common but does occur. Have a low threshold to whip out the sono if the patient deteriorates.