Bypass surgery -- or Coronary Artery Bypass Graft surgery (CABG) -- is open-heart surgery that:
The attachment is actually a bypass that creates a new pathway for blood to flow into the heart.
Removing the veins and arteries from one part of the body doesn't affect the blood flow in that part of the body. For instance, if a vein were taken from your leg, blood flow to that leg would not be affected.
Because bypass surgery is major surgery, it entails more risk and requires a longer recovery -- often about one year.