During a heart attack, blood flow to a section of the heart muscle is blocked suddenly, causing lack of oxygen, states the National Heart, Lung, and Blood Institute. The blockage is most often caused by coronary heart disease, a condition in which plaque buildup occurs inside an artery.
Plaque buildup inside a coronary artery sometimes ruptures, which causes a blood clot to form on the surface of the plaque. This blood clot can grow large enough to block the artery, causing a heart attack, states the National Heart, Lung, and Blood Institute. Spasm, or tightening, in the coronary artery is a less common cause of heart attack. Spasm can occur even in coronary arteries that do not have plaque buildup.
Prompt treatment of a heart attack is important because the section of heart muscle that is supplied by the blocked artery can die if there is prolonged lack of blood flow. Common symptoms of a heart attack include chest discomfort, shortness of breath, and discomfort in the arms, jaw, back or neck, according to the National Heart, Lung, and Blood Institute. Other possible symptoms, such as excessive fatigue, nausea, vomiting, lightheadedness and dizziness, may also occur. Emergency medical attention is advised for any person experiencing symptoms of a heart attack.