View our animation of what happens to your heart if you have a heart attack.
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Your heart muscle needs oxygen and nutrients to keep working. Blood that is rich in oxygen and nutrients is supplied to your heart muscle by the coronary arteries.
The walls of a healthy coronary artery are smooth and the vessel is open, allowing blood to flow smoothly.
Before a heart attack, there has usually been years of fatty deposit (plaque) build-up in the walls of the coronary arteries. This process of plaque build-up is called atherosclerosis. Atherosclerosis narrows the arteries and reduces blood flow.
If the surface of a coronary artery plaque ruptures or tears, it exposes the fatty deposits inside. Platelets — tiny cell fragments in the blood involved in clotting — then stick to the ruptured plaque, and a blood clot forms over the damaged artery wall. The blood clot may block the already-narrow coronary artery, cutting off the blood flow to the area of heart muscle supplied by the part of the coronary artery downstream of the clot. Within a few minutes of the blockage, the heart muscle cells are damaged and begin to die.
However, sometimes the damage can be reversed if the blood flow is restored quickly. If blood flow is not restored, the heart cells in that area will die and scar tissue can form. If a large area of the heart muscle dies, the heart can lose its normal rhythm and stop beating.
The sooner that treatment for the heart attack starts, the better the chance that blood flow to the affected tissues can be restored, and the more likely that heart muscle damage can be restricted or stopped. Remember, if you suspect that someone is having a heart attack, dial 000 for an ambulance — EVERY SECOND COUNTS.
Last Reviewed: 07 May 2010