A stroke is a serious complication that can occur during open heart surgery. The latest studies show that temporary or permanent strokes can occur in about 5 out of 100 procedures. Some of these strokes appear to be caused by a piece of plaque, which is a piece of calcium or a diseased part of the blood vessel or valve, that breaks off and travels through the arteries to the brain. When the piece of plaque blocks a small artery in the brain, it prevents blood and oxygen from reaching that area of the brain. The damage that results from the blockage is called a stroke. Your body can be affected by a stroke in a variety of ways, including paralysis, loss of speech, or even loss of life.