Is it dangerous for me to excercise and get my heartbeat up if i am at risk for an aortic dissection?

Could be: Yes, could be. Depends on the size of your aneurysm and any other condition such as marfan's or family history of ruptured aneurysm. Please check with your cardiologist or vascular surgeon.

Yes: Any reason that cause sudden and severe increase in blood pressure should be avoided . Most of dissections have no etiology but in unusual diseases like marian syndrome u could be at risk.