Heart Attack Causes - OmniMedicalSearch.com (Myocardial Infarction)

Conditions & Diseases: Cardiovascular System

Heart Attack (Myocardial Infarction)

Heart Attack Causes

The main cause of a heart attack is the lack of oxygen in a certain portion of the heart muscles. The lack of oxygen is caused, in most cases, by an obstruction in a coronary artery. An artery is the blood vessel that carries oxygen-rich blood. The obstruction can be the result of plaque build-up within the artery walls as a result of coronary artery disease. Unfortunately, arteries (particularly the coronary arteries) are prone to plaque accumulation (or atherosclerosis).

For a long period of time, it was thought that a heart attack is caused by the narrowing process that undergoes inside the artery due to atherosclerosis. It was believed that plaque builds up slowly until it obstructs the lumen (the channel within the artery where blood flows), therefore causing a heart attack. However, recent imaging expertise revealed that the size of the plaque is a predictor for the occurrence of a heart attack. Although one might think that a larger build up of plaque represents a greater risk, small plaque build ups are actually more prone to rupture and cause more heart attacks.

Plaque is a collection of dead tissue, cholesterol, fats, inflammatory blood cells, calcium, and scar tissue that is held in place by a fibrous cap. This fibrous cap is formed of scar tissue made of collagen. Due to unknown causes, the fibrous cap can weaken and crack exposing the internal components. When that happens, the body treats the crack similar to any other injury - it responds with blood-clotting components (usually platelets) that congregate at the rupture's site forming a thrombus (or blood clot). The presence of a blood clot can increase the risk of a heart attack. A blood clot can either restrict or completely stop the blood flow through the affected portion of artery.

The current belief is that arteries exhibiting a 40 to 50 percent or less narrowing due to plaque accumulation are more likely to cause heart attacks because they can contain what is called "soft" plaque, a type t hat is very unstable and more susceptible to abrupt ruptures.

A far less common cause of coronary artery obstruction is a coronary artery spasm that can temporarily shut down or reduce the blood flow to a portion of the heart muscle. Coronary artery spasms can be triggered by tobacco use, high cholesterol, high blood pressure, exposure to cold, extreme emotional stress, or the use of illegal drugs (such as amphetamine and cocaine).

Another rare cause of heart attack is microvascular disease. Microvascular disease is a condition in which very small branches of arteries become damaged. This damage results in blockage of the vessels, therefore impairing the blood flow.

Article by Alina Morrow, MS
Medical Writer
OmniMedicalSearch.com