Nowadays, this is a major cause of death and disability worldwide, sometimes called a “heart attack” or “coronary thrombosis”. This disorder occurs when the blood vessels which supply the heart are blocked. This prevents enough oxygen from reaching the heart and heart muscle death leading to permanent damage. There are different types of myocardial infarction which can be diagnosed by electrocardiography (ECG).The two main types are called:
1- ST elevation MI (STEMI) which occurs due to sudden thrombotic occlusion (formation of a blood clot) of a coronary artery.
2- Non-ST elevation MI (NSTEMI) which occurs due to an unstable plaque with aggregation of platelets in the blood vessels.
Although, the treatments depend on the type of myocardial infarction, aspirin, clopidogrel, beta blockers and statins are given to both. The disorder occurs because the heart consists of special muscle which is only supplied by coronary arteries. The main coronary arteries are divided into smaller branches which take blood to all parts of the heart muscle, but these may become blocked during a myocardial infarction. As a result, the heart loses its blood (and oxygen) supply and the heart muscle may die unless the blockage is quickly resolved. If the main coronary arteries are blocked, a large part of the heart muscle is affected; however, If a smaller branch artery is blocked, a smaller amount of heart muscle is affected. An STEMI myocardial infarction occurs due to complete blockage in the artery supplying an area of the heart muscle and an NSTEMI occurs due to partial blockage in the artery resulting in only part of the heart muscle being affected.
Causes:
The causes of myocardial infarction are divided into common and uncommon causes. The first type involves a blood clot (thrombosis) which forms inside a coronary artery or its branches causing death of heart muscle cells. The blood clot may form if there is some atheroma, fatty patches or plaques within the lining of the artery, and this blood clot stops the blood flow in the coronary artery. Additionally, atheromas may gradually form over a number of years in one or more places in the coronary arteries. The atheroma is the root problem that leads to most cases of myocardial infarction. Uncommon causes of coronary artery blockage leading to myocardial infarction may be: inflammation of the coronary arteries (rare), a stab wound to the heart; a blood clot forming in a heart chamber and travelling to a coronary artery, taking cocaine which causes spasm in the coronary artery, complications from heart surgery and various other heart problems.
Symptoms:
The major symptom of myocardial infarction is severe chest pain, which is like a heavy pressure feeling on the chest. This pain may also travel up into the jaw and down to the left or both arms. In addition, there are other symptoms that may be associated with this disease such as sweats, feeling sick and shortness of breath. This pain may be similar to angina, but it is more severe and lasts longer than 20 minutes and sometimes several hours.
Some people have only a mild discomfort in their chest during myocardial infarction. For example, the pain may feel like indigestion or heartburn. Also, there are other less specific symptoms, for instance: anxiety, cough, fainting, light-headedness, weakness, dizziness, nausea or vomiting and palpitations (awareness of irregular or fast beating of the heart). In some cases, a silent myocardial infarction may not exhibit any pain or symptoms. Finally, people may die in cases of severe myocardial infarction.