Health

The other kind is emergency surgery, which can't be scheduled, it has to be done right then.

Elective doesn't mean minor or unnecessary or even that the patient has a choice in the matter, it just means it can be scheduled.

The regular imaging scan with radioactive dye will show problems with blood flow. A CT scan with radio opaque dye will allow them to hone in on all the structures so that they won't be surprised by damage they didn't anticipate during surgery. A CT scan images the area slice by slice so that things that can't be visualized from the angle a plain angiogram provides can be visualized.

Cracking somebody's chest open for heart surgery is a huge deal and this surgeon is being very conscientious in making sure the process won't have to be repeated in the near future for a problem that should be taken care of now.