People often think that a heart attack is the same thing as a cardiac arrest. This, however, is not true. In order to understand the difference between a heart attack and a cardiac arrest, it is first necessary to understand what happens in both of these processes.
What is a heart attack?
The heart is a muscle, and like all muscles it requires an oxygen-rich blood supply. This is provided to the heart by coronary arteries. A heart attack occurs when there is a blockage of the coronary arteries. This is often caused by a blood clot. Such a blockage, if not quickly resolved, can cause parts of heart muscle to begin to die.
What is a cardiac arrest?
A cardiac arrest is different to a heart attack. In a cardiac arrest the heart actually stops beating; whereas in a heart attack the heart normally continues to beat even though the blood supply to the heart is disrupted.
Symptoms of a heart attack and of cardiac arrest
In addition to the physiological mechanism being different, the symptoms of a heart attack and a cardiac arrest also vary.
Symptoms of a heart attack include:
- Chest pain – this is often a feeling of tightness in the center of the chest which may last for several minutes and will not decrease upon resting (although the most common symptom of a heart attack, not all patients having a heart attack will experience chest pain)
- Spreading of chest pain to other areas, most commonly to the arms, jaw, neck, back and abdomen
- Shortness of breath
- Feeling or being sick
- Light-headedness or dizziness
- Palpitations (noticeable heartbeats)
Symptoms of a cardiac arrest include:
- Sudden loss of consciousness/responsiveness
- No breathing
- No pulse
The lack of pulse is caused by the heart actually stopping during a cardiac arrest. As a consequence of this, the organs of the body are deprived of blood – this can lead to death.
The following warning signs may also occur in the period before a cardiac arrest:
- Chest pain
- Shortness of breath
Causes of heart attacks and cardiac arrests
Cardiac arrests have several potential causes. These include:
- Ventricular fibrillation – an abnormal heart rhythm (arrhythmia) where the lower chambers of the heart (the ventricles) beat irregularly
- Ventricular tachycardia
- Coronary heart disease
- Changes of the heart structure
- Pacemaker failure
- Respiratory arrest
- Dramatic drop in blood pressure
- Drug abuse
- Excessive alcohol consumption
- An unknown reason
A cardiac arrest can also be caused by a heart attack. In fact, according to the British Heart Foundation, the majority of cardiac arrests in the UK are caused by heart attacks.
A heart attack itself involves a cut off in the blood supply to part of the heart muscle. If a large enough portion of the heart is affected, then the heart may stop beating, i.e. a cardiac arrest may occur.
But what about heart attacks themselves? What causes them? Well, in contrast to cardiac arrests, heart attacks are generally caused by one main factor – coronary heart disease (CHD). CHD is a condition that is generally caused by fatty deposits building up in the coronary arteries, which provide oxygenated blood to the heart. This is also known as atherosclerosis. Those most at risk of CHD include:
- Those who eat an unhealthy diet – one that is high in saturated fat
- Those with high blood pressure
- Those with diabetes
- Overweight or obese people
- People who do not exercise frequently
- Older people, in particularly older men
- Those with a family history of heart disease
- People who have been exposed to air pollution, particularly traffic pollution
People with CHD may experience a heart attack if a plaque, (a raised patch on the artery wall) splits and causes a blood clot which in turn blocks the coronary artery.
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