Ventricular Fibrillation (VF) in Singapore: Causes, Emergency Response and Treatment

Ventricular fibrillation (VF) is the most dangerous heart rhythm: instead of pumping, the ventricles – the heart’s main chambers – quiver chaotically, so blood flow stops within seconds and the person collapses. VF is the electrical event behind most cases of sudden cardiac arrest, and it is fatal within minutes unless corrected with a defibrillator shock. If a loved one has survived VF, or a family history has raised your concern, this page explains what VF is, what causes it, exactly what to do in an emergency, and how those at risk are protected. It is general information and not a substitute for advice from your own doctor.

What Is Ventricular Fibrillation?

In a normal heartbeat, the ventricles contract together to push blood to the body. In ventricular fibrillation, the electrical signals become completely disorganised. The ventricles no longer contract – they quiver, or fibrillate – and pump no blood at all. The result is cardiac arrest: circulation stops, the brain is starved of oxygen, and within seconds the person loses consciousness, stops breathing normally and becomes unresponsive.

VF is an immediate emergency, not a fast heartbeat you can feel. It often follows a run of ventricular tachycardia (a fast but organised ventricular rhythm) that degenerates into chaos. Once VF begins, only an electric shock from a defibrillator can reset the heart – the sooner that happens, the better the chance of survival.

When to Seek Emergency Help: Call 995, Start CPR, Use an AED

If someone collapses, is unresponsive and is not breathing normally, treat it as cardiac arrest caused by VF:

1. Call 995 immediately and put the phone on speaker – the SCDF operator will guide you through CPR.
2. Start chest compressions – push hard and fast in the centre of the chest, about 100 to 120 compressions per minute, and do not stop until help arrives. Hands-only CPR is far better than doing nothing.
3. Send someone for the nearest AED (automated external defibrillator – a portable device that analyses the rhythm and delivers a shock if needed). AEDs are placed across Singapore in MRT stations, malls, community centres and HDB blocks, and are designed for untrained users: switch it on and follow the voice prompts.
4. The SCDF myResponder app alerts registered volunteers to nearby cardiac arrests and maps the nearest AEDs.

Every minute without CPR and defibrillation lowers the chance of survival. Bystander action is what saves lives. Cardiac arrest and its wider management are covered on our sudden cardiac arrest page.

Ventricular Fibrillation Symptoms

VF itself has no gradual symptoms – it causes sudden collapse. However, warning signs sometimes appear in the days or weeks before an event and are often missed:

• Fainting or blackouts, especially during exercise or emotional stress
• Sudden palpitations followed by light-headedness or near-collapse
• Chest pain on exertion
• Unexplained breathlessness
• A family history of sudden, unexplained death before the age of 50

Anyone with these features should be assessed rather than waiting to see whether they recur.

Causes and Risk Factors

• Coronary artery disease and heart attack – the leading cause in adults. A heart attack, or scarring from an old one, can trigger VF. The same risk factors apply: high blood pressure, diabetes, high cholesterol and smoking.
• Weakened or thickened heart muscle (cardiomyopathy) – a heart with reduced pumping function or abnormal thickening is more prone to VF.
• Inherited electrical conditions (channelopathies) – Brugada syndrome and long QT syndrome affect the heart’s electrical channels in a structurally normal heart. Brugada syndrome is notably relevant in Southeast Asian populations and can cause arrest during sleep in otherwise healthy young men.
• Other triggers – severe electrolyte disturbances, drug toxicity, myocarditis (inflammation of the heart muscle), and a precisely timed blow to the chest (commotio cordis).

How Ventricular Fibrillation Risk Is Assessed

For survivors and those at risk, the aim is to find the cause and prevent a recurrence:

• Electrocardiogram (ECG) – can reveal inherited electrical syndromes, thickened muscle or previous damage.
• Echocardiogram – an echocardiogram (ultrasound scan of the heart) measures pumping strength and muscle thickness; a significantly weakened heart is the strongest single predictor of risk.
• Coronary angiogram – checks for blocked arteries as a treatable cause.
• Cardiac MRI and genetic testing – to characterise muscle disease and screen family members.
• Heart screening – for young people in competitive sport or NS training who have symptoms or a family history, and for first-degree relatives of anyone who died suddenly and unexpectedly, structured heart screening with a cardiologist is worthwhile.

Treatment and Prevention Options

• Immediate treatment is defibrillation and advanced resuscitation, followed by intensive care and a full search for the cause.
• Implantable cardioverter-defibrillator (ICD) – the mainstay of prevention. For VF survivors and people at high risk, an ICD continuously monitors the rhythm and automatically delivers a shock to stop a life-threatening arrhythmia. Our cardiac pacemakers and devices service explains what implantation involves.
• Treating the underlying disease – angioplasty and stenting or bypass surgery for coronary disease, medication for heart failure, and specific management plans for inherited conditions.
• Risk factor control – managing blood pressure, cholesterol, diabetes and smoking reduces the coronary disease that drives most cases in older adults.

When to See a Cardiologist

See a cardiologist promptly if you have fainted during exertion, have palpitations with near-blackouts, or have a family history of sudden unexplained death or an inherited heart condition. If you have survived a cardiac arrest, specialist follow-up is essential. Identifying a cause early allows protective treatment before an emergency ever happens.

Frequently Asked Questions

Is ventricular fibrillation the same as cardiac arrest?

VF is the most common rhythm that causes cardiac arrest. In VF, the ventricles quiver instead of pumping, so blood flow stops and the person collapses. Cardiac arrest is the resulting loss of heart function, which requires immediate CPR and defibrillation.

Can you survive ventricular fibrillation?

Yes, if treatment starts fast. Survival depends on immediate CPR and early defibrillation with an AED – which is why calling 995, starting compressions and using the nearest AED without delay matter so much. Survivors are then investigated and usually protected with an ICD.

What is the difference between VF and VT?

Ventricular tachycardia (VT) is a fast but organised rhythm in which the ventricles still pump, though poorly. Ventricular fibrillation is completely chaotic, with no effective pumping at all. VT can deteriorate into VF, which is why VT is treated seriously.

What causes ventricular fibrillation in young people?

In younger people it is more often due to inherited electrical conditions such as Brugada syndrome or long QT syndrome, inherited cardiomyopathies, or myocarditis, rather than coronary artery disease. Family screening is important when a young person is affected.

How is ventricular fibrillation prevented?

By treating the underlying cause – coronary disease, heart failure or an inherited condition – and, for those at high risk, implanting an ICD to detect and shock a dangerous rhythm automatically. Controlling heart disease risk factors also lowers the chance of an event.