What causes a heart attack? A heart attack (or "myocardial infarction") occurs when blood flow to a part of the heart is blocked (often by a blood clot). This happens because coronary arteries that supply the heart with blood slowly become clogged from a buildup of cells, fat and cholesterol called "plaque."

Blood that tries to flow through these clogged arteries may form a clot. If this clot cuts off blood flow completely, the part of the heart muscle supplied by that artery begins to die; thus the importance of getting to the nearest hospital emergency room as fast as possible. New thrombolytic (clot-busting) drugs are now available that may be administered upon arrival to the emergency room to break up blood clots; hopefully preventing further damage to the heart muscle.

If you or someone you know find yourself experiencing any of the above symptoms, don't wait to seek help. Half of all people having an actual heart attack wait more than two hours before getting help! Others feel it would be embarrassing to go to a hospital, only to have a "false alarm," or possible indigestion. These feelings of fear are easy to understand, but they're also very dangerous.

When heart attack is suspected, immediately call 911. If you can get the person to the hospital quicker by driving them yourself (rather than waiting for an ambulance), do it. If you're the one having the heart attack, DO NOT DRIVE YOURSELF TO THE HOSPITAL! Ask someone to drive you or wait for an ambulance. Get to the nearest hospital offering emergency cardiac care as safely and quickly as possible.