Myocardial infarction is the necrosis of a section of heart muscle tissue, most commonly from coronary occlusion. Often referred to as a heart attack, myocardial infarction occurs suddenly, but is usually the result of long-term conditions.

Typically the coronary arteries are thickened with cholesterol plaques over the course of many years, increasingly narrowing the lumenal space. The rupture of a plaque can result in the formation of a blood clot, which causes complete occlusion of the arterial lumen if it grows too large, blocking the flow of blood and the oxygen it contains to the heart. Scientist have not yet determined exactly what causes plaques to rupture, but a number of risk factors for myocardial infarction have been identified, including diabetes, smoking, inactivity, being overweight, high LDL and low HDL cholesterol levels, high blood pressure, and increased adrenaline.

Being able to recognize the signs that someone is experiencing a myocardial infarction is important for making sure appropriate care is provided in a timely manner. Patients have a very high survival rate if they are admitted to a hospital, but hundreds of thousands of Americans die each year from heart attacks before the ever reach a medical center. The most common symptoms of myocardial infarction include chest pain or pressure that may radiate into the jaw, shoulders, arms, or back, shortness of breath, nausea, vomiting, low blood pressure, quickened pulse, lightheadedness, sweating, and anxiety. The severity of such indicators can vary significantly depending upon the extent of heart tissue affected. Some individuals may experience such mild symptoms that they do not realize that anything serious is wrong, resulting in what is often called a silent heart attack.

Myocardial infarction was initially described in the early 1900s by American physician James Brian Herrick. Though initially called coronary thrombosis due to the primary cause of the condition, eventually myocardial infarction became the preferential term due to the fact that death to the heart muscle is directly responsible for the pain and other signs of a heart attack, rather than the arterial blockage that usually precedes it. Over the course of the last century, much has been learned about myocardial infarction and a number of diagnosis methods have been developed. Electrocardiograms, magnetic resonance imaging, and a variety of blood tests can be used as indicators of heart muscle tissue necrosis. However, because blood flow to the heart must be restored as quickly as possible in order to minimize damage, some tests are more useful as a means to confirm diagnosis rather than as a way to first determine that a patient is experiencing a myocardial infarction. Fortunately, experienced emergency response team members and other medical professionals can generally identify most instances of heart attack simply based on symptomatic evidence.

Treatments for myocardial infarction are generally highly successful if administered in time. Anti-platelet medications, such as aspirin, and anti-coagulants, like heparin and warfarin are often the first line of therapy, and together can effectively prevent additional clotting of the blood from taking place. To dissolve blood clots that have already formed, however, one or more thrombolytic medications, among the most commonly used of which are tissue plasminogen activator (TPA) and tenecteplase (TNK), must be administered. When these drugs are unable to be used due to other health conditions of the patient or when they are ineffective, a surgical means of opening the affected artery becomes necessary. Stenting may be used in conjunction with any of several different surgical techniques to ensure that the artery remains open. Nitrates and angiotensin converting enzyme (ACE) inhibitors, which dilate blood vessels, beta-blockers, which are antagonists of adrenaline, and oxygen, which can help minimize the extent of damage to the heart, are also often administered to patients at various points in their treatment for myocardial infarction.

Myocardial Infarction at 40x Magnification - Millions of living Americans have suffered from one or more instances of myocardial infarction. Many of these individuals carry out all of their normal activities, but are at increased risk for additional occurrences of myocardial infarction and other heart problems.

Myocardial Infarction at 10x Magnification - Controlling weight as well as blood pressure and cholesterol levels is very important for heart-attack survivors and can often be achieved with a low-fat diet containing many fruits and vegetables and regular exercise. For some, a regimen of cholesterol-lowering drugs and other medications, such as aspirin or beta-blockers, may be advised.