The blood flowing through the coronary arteries carries oxygen to the heart. Sometimes deposits of substances like cholesterol on the walls of the arteries cause narrowing and hardening of these blood vessels. Blockage of an artery in this way starves the heart of oxygen. If the blockage is mild only pain results. If severe, the part of the heart that is starved of oxygen actually dies—this is what we call a heart attack.
Sometimes after a heart attack, surgeons attempt to open up a clogged artery through a technique called 'Balloon Angioplasty.' In balloon angioplasty, a long tube (catheter) with a balloon at one end is inserted through the groin and is guided to the clogged artery in the heart. At the site the balloon is inflated. The inflated balloon crushes the plaque (deposit) on the artery wall. The balloon is then deflated and withdrawn.
Besides balloon angioplasty there is another technique called laser angioplasty in which a laser beam is used to cut through the plaque.