Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Aneurysms ?
    ### Response:
    An aneurysm is a bulge or "ballooning" in the wall of an artery. Arteries are blood vessels that carry oxygen-rich blood from the heart to other parts of the body. If an aneurysm grows large, it can burst and cause dangerous bleeding or even death.     Most aneurysms occur in the aorta, the main artery that runs from the heart through the chest and abdomen.
    