Paris Heart Centre

 

Heart Attack (myocardial infarction)

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Chest Pain Clinic	Specialist Interventional Nurse
Specialist Nurse Rehabilitation	Cardiology
Specialist Nurse Electrophysiology

The heart is a specialised muscle pump which is designed to move blood around the body to supply vital organs with oxygen. It is divided into 4 parts known as chambers. There are two small chambers at the top of the heart (the right atrium and the left atrium) and two larger chambers at the bottom of the heart ( the right ventricle and the left ventricle). The left ventricle is the main pumping chamber.

The heart muscle itself needs to be supplied with oxygen. This is done through arteries around and through the heart muscles. When the bloodflow through one of these arteries is restricted by a blockage or clot, some of the heart muscle can be deprived of oxygen and be damaged. For the sufferer this can cause severe pain in the chest. This is a heart attack or myocardial infarction.

The symptoms of a heart attack include (all or some):

• pain in the chest, spreading to the arms, face, back or stomach.
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• sweating
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• nausea
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• shortness of breath
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• abnormal heart rhythm

In severe attacks these can quickly be followed by unconsciousness or death.

Heart attacks can be less dramatic. The heart muscle may only be lightly damaged and can carry on its work after the attack has passed. The sufferer may experience only mild discomfort. Any damage to the heart will only be revealed by subsequent routine medical investigation.

Causes

The primary reason why an attack occurs is the build up of fatty tissues inside the arteries. This does not occur suddenly but takes a number of years. The build up of tissues eventually restrict the blood flow so much as to cause a blockage. The arteries also may have cracked. These damaged areas now become targets for the platelets in the blood who try to clot these breaches. While trying to cover the damaged area of the artery the clot also blocks the artery potentially causing the sudden heart attack.

The onset of a heart attack

A persons susceptibility is due to a variety of factors. There is no single reason why they occur when they do. Each element in the list below plays its part.

Lifestyle - smoking, hypertension (high blood pressure), high blood cholestrol and lack of physical activity)

Heredity - heart problems can run in families e.g. hyperlipidaemia.

Diabetes - sufferers are more likely to have/get heart disease.

Cardiac Arrest

This happens when the electrical system of the heart becomes disturbed. The signals that coordinate the heart muscles, into a useful pump action, become chaotic. The useful heart output is reduced to nothing. The heart doesn't actually stop but quivers. This is know as fibrillation. The electrical activity of the heart is such that the main signal, that sets the heart rhythm, cannot reset the normal heart rhythm.

The effect on a person suffering a cardiac arrest is almost instant. The person will lose consciousness, no pulse will be present and breathing may stop. Emergency measures are needed quickly if the person is to survive. Resuscitation needs to be done within 3 to 4 minutes of the arrest before the brain becomes starved of oxygen. Chest compressions and chest inflations (mouth to mouth) need to be maintained until equipment is available to restart the heart. Resuscitation alone will not restart the heart. A de-fibrillator is needed. This machine is used to deliver an electric shock to the heart muscle through the chest wall. This technique is very often successful in restoring a normal heart beat.

Examples of portable defibrillator machines.

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