Cardiac Arrest

What is cardiac arrest?

Cardiac arrest refers to the sudden loss of function of the heart. It occurs when there is an abrupt disturbance in the heart’s rhythm. This can cause the heart to stop beating, or to stop beating enough to keep the person alive. It can occur in a person with or without heart disease.

A person whose heart has stopped beating will fall unconscious and stop breathing normally. If the person does not get immediate medical assistance, sudden cardiac death will follow.

What is sudden cardiac death (SCD)?

Sudden cardiac death (SCD) is the death of a person due to the sudden loss of function of the heart. This type of death is rarely expected because often no symptoms are seen until the person suffers a cardiac arrest.

Isn’t cardiac arrest the same as a heart attack?

No. A heart attack refers to the death of heart muscle tissue due to the loss of the blood supply. While a heart attack can lead to cardiac arrest and SCD, it does not always do so. Therefore there is a distinction.

What causes cardiac arrest/sudden cardiac death?

There are a number of possible causes for the abrupt disturbance in heart rhythm that occurs when somebody has a cardiac arrest. These include:

  • Heart attack – this is the most common cause of cardiac arrest in adults
  • Heart abnormalities such as cardiomyopathy (a disorder of the heart muscle) or an electrical abnormality in the heart
  • Drugs overdose
  • Suffocation
  • Anaphylaxis
  • Hypothermia
  • Electrocution
  • Drowning
  • Choking
  • Trauma

The majority of adults who have experienced a sudden cardiac death are subsequently found to have some degree of coronary artery disease (fatty build-up in the arteries leading to the heart). This has caused the heart attack and the resulting cardiac arrest. However, when a sudden cardiac death occurs in a young adult/child, other heart abnormalities that have been present from birth are normally the cause. These often go by undetected.

Am I at risk?

People who have previously had a heart attack or who have coronary artery disease are most at risk of cardiac arrest. The following could also be signs of having an underlying heart problem:

  • A family history of sudden cardiac death
  • Chest pain on effort
  • Breathlessness on effort
  • Dizziness or fainting of unknown cause
  • Irregular or fast heart beat.

If you are concerned you may be at risk, you should consult your GP. Your GP will ask you about your symptoms and any family history, and can carry out medical examinations for possible heart defects.

Does taking part in sport cause sudden cardiac death?

A number of high profile sudden deaths of young athletes in this country in recent years has drawn the public’s attention to sudden cardiac death. However, it should be remembered that SCD is very rare in previously fit and healthy young people, and is most commonly seen in older people, when it is often related to coronary artery disease.

Taking part in sport does not cause sudden cardiac death. However, if a person has a serious, undetected, underlying heart problem – the over-exertion that occurs during sport could act as a trigger for cardiac arrest.

If you are concerned about having a heart disorder (see ‘Am I at risk’ section above), you should talk to your GP.

If a person has a cardiac arrest, is there anything anyone can do to help prevent Sudden Cardiac Death?

In most cases, cardiac arrest is reversible, but only if the victim is treated within a few minutes of the arrest occurring. CPR (cardio-pulmonary resuscitation – a manual technique used to restore circulation) and if possible, defibrillation (the administration of a controlled electric shock to the heart) can save a person’s life if applied early enough.

Brain damage can occur within a few minutes of cardiac arrest and few attempts at resuscitation succeed after 10 minutes have passed. Therefore time is absolutely essential.

If someone has a cardiac arrest:

  • Call an ambulance immediately on 999 or 112 and tell them it is a cardiac problem so that they are aware your call is a priority.
  • If you know how, start CPR immediately (find our more about CPR).
  • If there is an Automatic External Defibrillator (AED) in the vicinity and a person present who is trained in its use, defibrillation can be applied. This can restore a normal heart rhythm if given within a few minutes of a cardiac arrest.

Do not under-estimate the importance of knowing First Aid – even if your knowledge is basic, it could help save a life.

While previously just available to health professionals, Automatic External Defibrillators (AEDs) have been made more widely available in the community in recent years: devices are now often placed in public locations where large numbers of people congregate or where incidence of cardiac arrest may be high – e.g., sports venues, health facilities, airports and shopping centres. Individuals need to be trained in the use of the device.

If normal rhythm returns to the heart, will the person be alright?

Not necessarily. Sometimes life-saving measures come too late. In such cases, the heart may return to its normal rhythm, but the brain may already be severely damaged.

Remember, time is the key. Never forget that when dealing with a suspected cardiac arrest.

Reviewed: November 16, 2006