This is a different disease from AAA. In aortic dissection a trigger (usually high blood pressure) causes a tear in the wall of the main blood vessel (aorta). This creates a new second channel in the wall of the blood vessel for blood to flow through and resembles a double barrelled shotgun. Aortic dissection can cause a number of symptoms but typically causes severe back or belly pain and sweating or collapse. It can be diagnosed using a combination of blood tests and CT scans.