Myocardial infarction, commonly called a heart attack, is the death of heart muscle resulting from the sudden blockage of a coronary artery by a blood clot. Blockage deprives the heart of blood and oxygen. Damage to the cardiac muscle causes pain, which can be severe or mild, lasts longer than 20 minutes, is not completely relieved with rest or taking nitroglycerine. The pain may go away but comes back with increasing episodes. The pain of a heart attack can present as pressure, a feeling of fullness or squeezing in the center of the chest. The pain radiates to the shoulders, arm, back, teeth and jaw. It can also be felt in the upper abdomen. Commonly associated symptoms include shortness of breath, sweating, impending sense of doom, fainting, nausea and vomiting. For women, the pain of a heart attack may present as abdominal pain or heartburn, accompanied by unexplained fatigue, clammy skin and feeling lightheaded or dizzy. At the onset of any of these symptoms immediately call 911 for emergency medical attention.