The problem with many of the responses here is that often people would just look up an answer, and even if doesn't fit, will copy and just post it anyway. The Aortic valve
, other than facing the other direction of flow, has nothing to do with the Mitral Valve at all.
The problem that you delineated is a complicated but relatively common procedure. The aorta
around the aortic valve is damaged (blood has leaked in between the layers of that main artery
, ie the aneurysm
). It is too close to the structure of the aortic valve to effect repair without cutting into the tissue that supports that valve. Since the aortic valve is bad anyway (stenosis, that is, it doesn't fully open because it has a fused flap, making it two flap instead of the normal three) they will take out the part of the heart that contains the Aortic valve and several inches of dissected (or separated) aorta.
If you look at the aorta and valve like a fitting in the shower spigot, they will essentially cut out the section of wall that the spigot sits in along with the connecting piece of spigot, and replace the entire assembly from a cadaveric donor.
Look up "Aortic homograft" on google images to get a better idea of the structural replacement.
And good luck to your Dad.