Myocardial infarction is the sudden death of part of the heart muscle due to a blockage in the blood supply to that area of the heart. The disorder is popularly known as a heart attack. Myocardial infarction is fatal in about 25 per cent of cases.

MYOCARDIAL INFARCTION CAUSES

The usual cause is atherosclerosis of the coronary arteries. In this condition, plaques (fatty deposits) develop on the artery walls; a clot may then form over a plaques and block an artery. Men are more likely to have a heart attack than women, and smokers are at greater risk than nonsmokers. Other risk factors include increased age, an unhealthy diet, obesity, lack of exercise, disorders such as hypertension (high blood pressure) and diabetes mellitus, and a family history of myocardial infarction at a young age.

MYOCARDIAL INFARCTION SYMPTOMS

There is a sudden, crushing pain that starts in the center of the chest and may spread into the arms or up to the jaw. Breathlessness, restlessness, clammy skin, and nausea and/or vomiting may also occur. In some cases, the first symptom is sudden collapse and loss of consciousness. A few people have only mild symptoms of have none at all; this type of heart attack is known as a silent myocardial infarct.

The damage to the heart tissue may cause immediate heart failure (reduced pumping efficiency) or arrhythmias (irregular heartbeat). Ventricular fibrillation is the most dangerous form of arrhythmia; it prevents the heart from pumping effectively and, if untreated, is fatal within a few minutes.

MYOCARDIAL INFARCTION DIAGNOSIS

Diagnosis is made from the patient’s history, together with an ECG. Tests are also carried out to measure levels of certain enzymes, and of a protein called troponin, which are released into the blood from damaged heart muscle.

MYOCARDIAL INFARCTION TREATMENT

A myocardial infarction is a medical emergency and the sooner treatment is given, the greater the chance of survival. If a person is having a heart attack, he or she will normally be given an aspirin tablet to chew immediately to stop the clot in the artery from becoming larger and will be taken to hospital as soon as possible.

Initially, oxygen and diamorphine are given in order to relieve the pain and intravenous thrombolytic drugs (clot busters) may be given to dissolve the blood clot (unless there is a risk that the drugs will cause excessive bleeding) If thrombolytic drugs fail to restore blood flow in the affected artery, an emergency angioplasty may be carried out, usually with insertion of a stent (rigid tube) in the artery to keep it open. Alternatively, a coronary artery bypass graft may be performed.

Afterwards, patients are monitored in an intensive care or coronary care unit so that any complications, such as heart failure, arrhythmias, or rupture of a heart valve can be detected and treated as early as possible.

After recovery from a heart attack, patients may be given beta-blocker drugs or ACE inhibitors to improve the function of the heart and to protect the heart muscle. Statin drugs may also be prescribed to lower blood cholesterol. In addition, patients will undergo a rehabilitation programme to help them return to full activity and to increase awareness of risk factors.

Source: A-Z family medical encyclopedia by BMA

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