Blood then flows from the aorta through the vein graft beyond the blockage to the coronary artery and to the heart muscle.
Sometimes, coronary bypass surgery needs to be repeated after about 10 years or so because the arteries become blocked again.
It is an open heart surgery in which the cardiovascular surgeon cuts through the sternum (breastbone) and exposes the heart.
The success of the surgery depends on the location and the amount of coronary artery disease, the time over which it has occurred and the blood vessels used for bypass.
Coronary artery bypass graft