A heart attack—also called myocardial infarction or MI—occurs when an area of heart muscle is completely deprived of blood, and the heart muscle cells die.
A heart attack may result when plaque inside the heart arteries breaks open or ruptures, forming a clot that significantly blocks blood flow through the artery.
A plaque is made up of cholesterol, white blood cells, calcium, and other components, and it is surrounded by a fibrous cap. This fibrous cap may tear or rupture if blood suddenly flows faster or if the artery suddenly narrows.
A tear or rupture signals the body to repair the injured artery lining—much as it might heal a cut on the skin—by forming a blood clot to seal the area. A blood clot that forms in an artery can completely block blood flow to the heart muscle and cause a heart attack.
Symptoms of a heart attack include:
Chest pain or pressure, or a strange feeling in the chest.
Shortness of breath.
Nausea or vomiting.
Pain, pressure, or a strange feeling in the back, neck, jaw, or upper belly, or in one or both shoulders or arms.
Lightheadedness or sudden weakness.
A fast or irregular heartbeat.
Call 911 or other emergency services immediately if you think you are having a heart attack. Medicines and procedures like angioplasty get blood flowing back to the heart to prevent death.
Heart attack symptoms not go away with rest or nitroglycerin.