Heart Attack and Acute Coronary Syndrome

What are heart attack and acute coronary syndrome?

A heart attack, also called an acute myocardial infarct (AMI), 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. Without prompt medical treatment, this blockage can damage or destroy heart tissue and can kill. Acute coronary syndrome (ACS) is a group of signs and symptoms that are associated with insufficient blood flow to the heart. A heart attack causes ACS, but there are some other conditions that can also reduce blood flow to the heart, resulting in similar signs and symptoms. When someone is rushed to the emergency room, testing must be performed to determine whether or not a person's signs and symptoms (ACS) are due to a heart attack or to another cause.

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 its own dedicated network of veins and arteries.

A blockage is usually caused by a blood clot that becomes lodged in an artery. This most frequently occurs in arteries that have narrowed, thickened walls. The thickening is caused by a gradual build-up of plaque in a process called atherosclerosis. A blood clot may form in or near the heart, or a piece of a clot may break away from a blood clot that has formed in another part of the body, such as in the leg, and then travels to the heart (embolism). The acute blockage of blood flow caused by a 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.