An aortic aneurysm is a bulge in the aorta caused by a weakeness or a tear in the blood vessel wall. It is usually caused by cardiovascular diseases, in particular high blood pressure and atherosclerosis (hardening of the arteries). Treatment of an aortic aneurysm involves either conventional surgery with complete removal of the bulge and suturing in of a vascular prosthesis, or endovascular repair using a catheter, through which a metal mesh covered with polyester fabric (stent graft) is inserted into the aorta. The Swiss Atlas of Healthcare contains analyses on the frequency of aortic aneurysm treatments overall and separate analyses on open surgery procedures and stent prostheses.