Symptoms

Collapse and loss of consciousness is the most common symptom of ventricular fibrillation.

Warning signs and symptoms

Before a ventricular fibrillation episode, you may have signs and symptoms of an abnormally fast or erratic heartbeat (arrhythmia). These warning signs may include:

• Chest pain
• Very fast heartbeat (tachycardia)
• Dizziness
• Nausea
• Shortness of breath

When to see a doctor

Make an appointment with a heart doctor (cardiologist) if you have an unexplained, fast or pounding heartbeat.

If you see someone collapse, seek emergency medical help immediately. Follow these steps:

• Call 911 or your local emergency number.
• If the person is unconscious, check for a pulse.
• If no pulse, begin CPR to help keep blood flowing through the body until an automated external defibrillator (AED) is available. The American Heart Association recommends hands-only CPR. Push hard and fast on the person's chest — about 100 to 120 times a minute. It's not necessary to check the person's airway or deliver rescue breaths. Continue until emergency medical help arrives.
• Use an AED as soon as it's available. Deliver a shock following the prompts on the device.