Each year over a million people in the U.S. have a heart attack. About half of them die. Many people have permanent heart damage or die because they don't get help immediately. It's important to know the symptoms of a heart attack and call 9-1-1 if someone is having them. Those symptoms include

• Chest discomfort - pressure, squeezing, or pain
• Shortness of breath
• Discomfort in the upper body - arms, shoulder, neck, back
• Nausea, vomiting, dizziness, lightheadedness, sweating

These symptoms can sometimes be different in women.

What exactly is a heart attack? Most heart attacks happen when a clot in the coronary artery blocks the supply of blood and oxygen to the heart. Often this leads to an irregular heartbeat - called an arrhythmia - that causes a severe decrease in the pumping function of the heart. A blockage that is not treated within a few hours causes the affected heart muscle to die.

NIH: National Heart, Lung, and Blood Institute