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Sudden Cardiac Death

What is sudden cardiac death (SCD)?
The heart has an inbuilt electrical system, which makes it work. If this is interrupted, the heart cannot pump enough blood around the body. Without a supply of blood pumped by the heart the brain canít function, the victim faints and death follows within minutes. If treated quickly with an electric shock delivered by an automated external defibrillator (AED), normal heart rhythm can often be restored (the survival rates decreases by 10% per minute).

A SCD may be the first sign that the victim has had of a heart problem. In many cases, no definite cause of death can be found, even at autopsy. These deaths are thought to be caused by an arrhythmia and are labelled a Sudden Arrhythmic Death (SADS).

What causes SCD?
SCD can be caused by a number of different heart problems, many of which are inherited. Some of these conditions include:

Coronary heart disease (CHD) - narrowing of the blood vessels in the heart. CHD affects young people as well as older people.

Cardiomyopathy (hypertrophic & dilated) - heart muscle problems.One in 500 people have a gene which may lead to a condition called Hypertrophic Cardiomyopathy* (HCM), a heart muscle problem, which if undiagnosed can cause SCD.

Heart rhythm abnormalities (arrhythmia), such as Long QT Syndrome* & Brugada Syndrome*.

Diseases of the heart valves

Disease of the heartís electrical system short-circuiting the normal pathways between the different chambers of the heart, such as Wolff Parkinson White Syndrome*.

Other causes of SCD include electrocution, viral infection (Myocarditis*), blow to the chest and adverse reaction to drugs (legal & illegal).

Is SCD the same as a Heart Attack
No, but SCD may occur during the course of a heart attack. A heart attack is caused by the sudden blockage of a heart artery, which may lead to sudden cardiac death.

You may be at risk, if you have:

  • A family history of unexplained death (including cot death) in people under 35 years old.
  • Breathlessness on effort.
  • Chest pain on effort.
  • Dizziness, fainting and blackouts of unknown cause
  • Fast heart rate that comes and goes, even when you are resting.
  • Palpitations* due to an irregular heart rhythm (arrhythmia*).

If you have any of these symptoms, you should speak to your doctor (GP).
Investigations for possible heart problems include:

  • Medical examination including questions about your familyís medical history.
  • ECG* (electrocardiogram) and possibly an Echo* (echocardiogram) if indicated. These tests are painless and non-invasive.
  • Other more specialised tests may be neededsuch as a magnetic resonance intensifier (MRI)

Most of the conditions which cause sudden cardiac death can be treated.

  • 100 or more people under 35 years die on the island of Ireland each year from sudden cardiac death.
  • Athletes & non-athletes are at risk.

Does taking part in sport cause SCD?
Sport and physical activity is good for your heart. However if a person has a serious, undetected heart problem, over-exertion during sport can act as a trigger for sudden cardiac arrest and possible death.

When a personís heart stops, can anything help?
Yes. The chain of survival has 4 links that need to be made quickly to give the best chance of survival.

1. Get help, dial 112 (the new emergency phone number that replaces 999)

2. Perform CPR, which helps pump blood to the brain & other body organs.

3. Defibrillation with an automated external defibrillator (AED) delivers an electric shock to the heart if indicated by the rhythm that the defibrillator reads from the heart via the paddles placed on the chest. This is the only action that can restore a normal heartbeat rhythm.

4. Advanced care by a medical team.

When Sudden Cardiac Death occurs, other close relatives may also be at risk. A post-mortem examination is vital to identify the cause of death, to help determine if the death was due to an inherited condition and to help assess possible risks to other family members. The coroner, pathologist and family doctor all have important roles in this investigation.

Where can I train in CPR and to use an AED?
A national network of 120 training sites, affiliated to the Irish Heart Foundation provide training. Click here for a list of the sites amd their contact details.†


AED (Automated External Defibrillator): A machine that delivers an electric shock to help restore a normal heart rhythm. Members of the public can be trained to use AEDs.

Arrhythmia: Abnormal heart beat. The heart may beat too quickly, too slowly or in an irregular way.

Brugada Syndrome: An inherited disorder related to the membranes of heart muscle cells. It can result in life-threatening heart rhythms.

CPR: Provides rescue breaths and chest compressions to someone who has collapsed and is unresponsive. CPR helps keep oxygen-rich blood supplied to the brain and other body organs until medical helps arrives.

Defibrillation: This involves a trained person delivering an electric shock, with an AED, to the victimís heart to help restore a normal heart rhythm.

ECG (electrocardiogram): This test measures the rhythm & electrical activity of your heart. Small sticky pads are placed on your body connected to wires that link up to the ECG machine. The machine reads & records, on paper, the electrical signals from your heart.

Echo (echocardiogram): Use of ultrasound to view moving images of your heart muscle & valves.

Hypertrophic Cardiomyopathy (HCM): A disease of the heart muscle which does not allow the heart to pump blood around the body as well as it should.

Long QT Syndrome: An inherited disorder of the heartís electrical system. People may experience periods of very fast heart beat that may be life threatening.

Myocarditis: An inflammation of the heart muscle, most often caused by a viral infection. However it may also be due to a bacterial infection, rheumatic fever or an adverse reaction to some types of drugs.

Palpitations: The sensation of an irregular heart beat.

Sudden Cardiac Arrest: The heart stops working without warning

Wolff Parkinson White Syndrome: The heart has one or more extra electrical pathways that may cause abnormal heart rhythms.

Sudden Arrhythmic Death Syndrome Support Group
The group was set up in 2006 in association with the Irish Heart Foundation and grew from the friendship of parents who suffered the loss of a young person to sudden cardiac death.

The groupís services include:

  • Facilitating people whoíve suffered a similar loss to contact each other through our informal support network, nationwide.
  • Helping people get in touch with accredited bereavement counsellors.
  • Giving people access to medical information on heart problems.
  • Linking people to other Irish Heart Foundation support groups (Cardiomyopathy, Long QT Syndrome and ICD)

The group aims to:

  • Increase awareness surrounding sudden cardiac death
  • Encourage placement of Automated External Defibrillators (AEDs) in schools, sports venues and public places.
  • Encourage screening of our youth for heart conditions.

If you would like to contact a member of the committee, please contact the Irish Heart Foundation 01 6685001 or info@irishheart.ie

For more information, speak to an Irish Heart Foundation nurse in confidence on our National Heart and Stroke Helpline on Freephone 1800 25 25 50† Monday-Friday 9am-5pm with a late night on Thursdays until 7pm

Stroke Campaign
Call our helpline on 1890 432 787