Many Americans have undergone bypass surgeries—including former President Bill Clinton—but do we really understand what's involved?

Dr. Oz shows Oprah how a heart transforms after undergoing a bypass. First, a bypass graft is placed on the heart to get past the blockage in the artery. The grafts are typically taken from veins in the legs.

"But the question is, is this as good as what you were born with?" Dr. Oz asks. "And the fact is, God gave you the arteries that you're supposed to have. Manmade imitations are never as good."

Get an inside look at the aorta. »