Sudden cardiac arrest

Sudden cardiac arrest is the sudden, unexpected loss of heart function, breathing and consciousness. Sudden cardiac arrest usually results from an electrical disturbance in your heart that disrupts its pumping action, stopping blood flow to the rest of your body.

Sudden cardiac arrest is different from a heart attack, which occurs when blood flow to a portion of the heart is blocked. However, a heart attack can sometimes trigger an electrical disturbance that leads to sudden cardiac arrest.

Sudden cardiac arrest is a medical emergency. If not treated immediately, it causes sudden cardiac death. With fast, appropriate medical care, survival is possible. Administering cardiopulmonary resuscitation (CPR) — or even just compressions to the chest — can improve the chances of survival until emergency personnel arrive.

Symptoms Causes Risk factors Complications Prevention

Sudden cardiac arrest symptoms are immediate and drastic.

  • Sudden collapse
  • No pulse
  • No breathing
  • Loss of consciousness

Sometimes other signs and symptoms precede sudden cardiac arrest. These may include fatigue, fainting, blackouts, dizziness, chest pain, shortness of breath, weakness, palpitations or vomiting. But sudden cardiac arrest often occurs with no warning.

When to see a doctor

If you have frequent episodes of chest pain or discomfort, heart palpitations, irregular or rapid heartbeats, unexplained wheezing or shortness of breath, or fainting or near fainting or you're feeling lightheaded or dizzy, see your doctor promptly. If these symptoms are ongoing, you should call 112 or emergency medical help.

When the heart stops, the lack of oxygenated blood can cause brain damage in only a few minutes. Death or permanent brain damage can occur within four to six minutes. Time is critical when you're helping an unconscious person who isn't breathing. Take immediate action.

  • Call 112, or the emergency number in your area, if you encounter someone who has collapsed or is found unresponsive. If the unconscious person is a child and you're alone, administer CPR, or chest compressions only, for two minutes before calling 112 or emergency medical help or before using a portable defibrillator.
  • Perform CPR. Quickly check the unconscious person's breathing. If he or she isn't breathing normally, begin CPR. Push hard and fast on the person's chest — about 100 compressions a minute. If you've been trained in CPR, check the person's airway and deliver rescue breaths after every 30 compressions. If you haven't been trained, just continue chest compressions. Allow the chest to rise completely between compressions. Keep doing this until a portable defibrillator is available or emergency personnel arrive.
  • Use a portable defibrillator, if one is available. If you're not trained to use a portable defibrillator, a 112 or emergency medical help operator may be able to guide you in its use. Deliver one shock if advised by the device and then immediately begin CPR starting with chest compressions, or give chest compressions only, for about two minutes. Using the defibrillator, check the person's heart rhythm. If necessary, the defibrillator will administer a shock. Repeat this cycle until the person recovers consciousness or emergency personnel take over.

Portable automated external defibrillators (AEDs) are available in an increasing number of places, including airports, casinos and shopping malls. You can also purchase them for your home. AEDs come with built-in instructions for their use. They're programmed to allow a shock only when appropriate.

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