Heart Attack and Acute Coronary Syndrome

What is a heart attack and acute coronary syndrome?

The heart is a muscular organ that pumps blood throughout the body via a system of veins and arteries. Blood flows from the lungs, where it picks up oxygen via the pulmonary veins into the heart, and gets pumped out to the body, delivering oxygen to the tissues. The blood returns to the heart via the veins and gets pumped back to the lungs once again. In order to perform these tasks, the heart requires large amounts of oxygen that it obtains from blood.

An acute myocardial infarct (AMI) - also called a heart attack - is caused by a blockage in the heart's arteries that reduces or completely cuts off the blood supply to a portion of the heart. This blockage is usually caused by a blood clot that gets stuck in an artery, usually developing in an area of thickening inside the wall of an artery that restricts the flow of blood. The thickening is usually caused by a build-up of plaque and is called atherosclerosis. The acute blockage of blood flow caused by the clot, if present for more than an hour, can cause death of the heart muscle cells (infarct) and lead to scarring of the affected area of the heart.

Acute coronary syndrome (ACS) is the term used for signs and symptoms that result from insufficient blood flow to the heart. Symptoms may include sudden onset of chest pain, often radiating into the jaw, arm or shoulder; in persons who have angina, these symptoms may be more severe or longer-lasting than normal. Some patients may exhibit other symptoms, such as rapid pulse, nausea, vomiting, sweating, sudden onset of shortness of breath, or difficulty breathing; in some cases, these symptoms may occur without chest pain (particularly in older individuals and in those with diabetes). These symptoms may also be accompanied by a change in blood pressure. In women, symptoms are often less dramatic and more likely to be misinterpreted as due to another cause than in men. For more information on warning signs and the difference between those that occur in men and women, visit the links listed under Related Pages, Elsewhere on the Web. If you experience these symptoms, call 911 or your local emergency number. If medical help is not received promptly, irreversible damage to the heart muscle may occur.