Heart Attack and Acute Coronary Syndrome

The heart is a muscular organ that pumps blood throughout the body through a system of arteries and veins. Blood is pumped to the lungs, where it picks up oxygen and then passes back to the heart through the pulmonary veins, and is then pumped out to the rest of the body, delivering oxygen to the tissues. The blood then returns to the heart through the veins and is pumped back to the lungs once again. In order to perform these tasks, the heart itself requires large amounts of oxygen which it obtains from the blood present in the coronary arteries.

A heart attack, also called a acute myocardial infarct (AMI),  is caused by a blockage in the coronary 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 a thickened area inside the wall of an artery that restricts the flow of blood. The area is called an atheromatous  plaque and is usually caused by a build-up of fat and collagen and causes the artery to harden (atherosclerotic).  The acute blockage of blood flow caused by the clot, if present for more than approximately an hour, can cause death of the heart muscle cells (infarction) and leads 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  chest pain, often felt into the jaw, arm or shoulder; in persons who have angina, these symptoms may be more severe or longer lasting.  Some patients may show other symptoms, such as a rapid pulse, feeling sick, vomiting, sweating, sudden 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 below under Related Pages Elsewhere on the Web. If you experience these symptoms, call your local emergency number. If medical help is not received promptly, irreversible damage to the heart muscle may occur.