The phrase ‘heart attack’ is commonly used to describe a blockage in a heart artery. A more accurate name is myocardial infarction (MI). An MI is the sudden death of part of the heart muscle cells (myocardium) from a blockage of the blood supply to that part of the heart (coronary artery thrombosis). This is the final result of disease of the two coronary arteries that supply the heart muscle with blood and is one of the major killers in the UK. Layers (plaques) of cholesterol build up inside the coronary arteries (atherosclerosis). These can rupture, blocking the artery through the sudden formation of a blood clot on the ruptured plaque.

Occasionally the blockage is brought on by spasm of the muscle walls of the coronary arteries. It can also be the result of an abnormal, very fast heart rate, where the heart muscle demands more oxygen than the blood supply can provide.

MI occurs in 5 per 1000 people in the UK each year. It occurs more often in men than in women, and mostly in people over 40 years old.

The process of infarction causes severe pain, and the immediate reduction in heart efficiency causes a range of other symptoms. Half of those who die from a particular attack do so from heart stoppage (cardiac arrest) within 3 or 4 hours of onset, so anyone suspected of having a heart attack should receive urgent medical attention.

Symptoms

The common syptoms are:

• Crushing central chest pain. This often travels (radiates) to the neck, jaws, ears, arms and wrists. Less often, it travels to between the shoulder blades or to the abdomen.
• Breathlessness
• Clammy sweat and grey complexion! Dizziness, sickness and vomiting
• General weakness and a frightening sense of impending doom
  In the great majority of cases, people suffering a myocardial infarction may experience:
• Crushing central chest pain
• Breathlessness
• Clammy sweat and grey complexion
• Dizziness, sickness and vomiting
• A frightening sense that one is about to die
• Restlessness.

The pain often travels (radiates) from the chest to the neck, jaws, ears, arms and wrists. Less often, it travels to between the shoulder blades or to the abdomen. The pain does not pass on resting, as in Angina.

Severe pain is not always a feature. In less major cases, pain may be absent, and there is evidence that up to 20 per cent of mild heart attacks are not recognised as such, or even as significant illness, by those affected. This means that some people who, because of previous unrecognised attacks, are much more vulnerable than they or their doctors realise. Such people may be suffering progressive heart muscle damage.

Causes

The cause of an MI is the blockage caused by a clot (thrombosis) from a plaque of arteriosclerosis. This disease in turn has a number of risk factors, all of which ultimately increase the risk of an MI:

• Being male
• Smoking cigarettes
• Being overweight
• Having abnormally high blood pressure
• Having a high blood cholesterol level
• A diet high in saturated fats (animal fats)
• Diabetes
• A family history of heart disease
• Lack of regular exercise

Severe sudden stress causing a fast heart rate, usually in someone who already has coronary artery disease. Such disease often shows no symptoms until an MI happens.

Treatment

If there is no breathing, coughing, movement, or response to stimulation (being touched or spoken to) immediate lifesaving treatment with cardiopulmonary resuscitation (CPR) must be started. CPR consists of giving 15 chest compressions to massage the heart for every two mouth-to-mouth resuscitation breaths.

An ambulance crew or doctor arriving at the scene will give oxygen through a mask or nose tubes to increase the amount reaching the heart. They will also give a pain-relieving injection, and sometimes a diuretic injection to reduce fluid build-up in the lungs if this is a problem.

If the heart has stopped, the medical team at the scene or in hospital will try to restart the heart with a device called a defibrillator. This sends an electric shock across the chest, kick-starting the heart to beat again. Simple automatic defibrillators are becoming increasingly common in public places.

Clot-busting injections are now routinely used in hospital. These dissolve the clot in the heart artery and allow the damaged heart muscle to recover, sometimes completely. They must be given within 24 hours at the most. Because the heart rhythm may become temporarily abnormal as it recovers, this treatment is best given when the heart rhythm can be continuously monitored on an electrocardiogram (ECG). This can be done in an ambulance or in hospital.

Aspirin reduces the stickiness of blood. 300 milligrams given immediately as a tablet reduces the risk of further damage from new clots.

In a straightforward recovery it is normal to be home within a week or less. Work can be restarted 4-12 weeks after the MI, depending on the level of physical exertion involved with the job. Driving can restart after one month, but DVLA and insurance company must be informed of the MI as soon as possible.

Exercise-based cardiac rehabilitation programmes reduce the risk of future problems and help the return to a normal life. These usually start 6 weeks after the MI.