Heart surgery. Image 5 of 9. Length of prosthetic blood vessel being cut to fit with a hot wire tool. This prosthesis will be used to replace a section of the aorta damaged by an aortic aneurysm. This is a dangerous dilation of the wall of the aorta, which can rupture with fatal consequences. The prosthetic aorta will be attached to an artificial valve (black, centre) that was fitted during a previous operation. This valve replaced the aortic valve where the aorta leaves the heart. For a sequence showing the operation, see images M560/461 to M560/469.