Why do aneurysms burst?

Aneurysms are defined as bulges twice the diameter of the nearby normal vessel. Aneurysms burst when the artery wall becomes too weak for the blood pressure within. Urgent clinical examination by a vascular surgeon, then an ultrasound or CT angiogram if time permits before repair, may save life. The result of a timely repair at Royal Melbourne Hospital of Epworth is 90-95% success, while only 50% of patients survive an attempt to repair the aneurysm once it has burst.