Ventricular Fibrillation

Overview

Ventricular fibrillation (VF) is a life-threatening heart arrhythmia in which the lower chambers of the heart (ventricles) quiver completely irregularly and chaotically. In this condition, the heart cannot pump effectively and blood circulation stops. The brain, heart, and other vital organs rapidly become deprived of oxygen.

Ventricular fibrillation is the most common cause of sudden cardiac arrest. Instead of beating regularly, the heart vibrates 300-400 times per second. This chaotic electrical activity makes coordinated contraction of the ventricles impossible. The heart stops pumping blood and the person loses consciousness within seconds.

Ventricular fibrillation is a medical emergency. Without intervention within minutes, it is fatal. Each passing minute reduces the chance of survival by 10 percent. Brain damage begins within five minutes. After ten minutes, permanent damage or death becomes inevitable.

Ventricular fibrillation usually develops during a heart attack, electrical shock, or serious heart disease. Rarely, however, it can also occur suddenly in apparently healthy people. This is an important cause of sudden deaths seen especially in young athletes.

Survival from ventricular fibrillation depends on emergency defibrillation (electrical shock). Early cardiopulmonary resuscitation (CPR) and rapid defibrillation save lives. An implantable cardioverter defibrillator (ICD) prevents sudden death in high-risk individuals.

Symptoms

Ventricular fibrillation develops suddenly and creates immediate symptoms.

The symptoms of ventricular fibrillation are:

• Sudden loss of consciousness. This is the most noticeable symptom. The person collapses to the ground within seconds and becomes unresponsive.
• Cessation of breathing. Normal breathing stops or agonal breathing (gasping) is seen.
• Absence of pulse. No pulse can be detected.
• Immobility. The person is completely motionless and does not respond to stimuli.

In some people, brief warning symptoms may occur just before ventricular fibrillation:

• Chest pain. This is seen especially in VF that develops during a heart attack.
• Rapid heart palpitations. Ventricular tachycardia may start first and then convert to VF.
• Dizziness. Brief dizziness may occur just before VF begins.
• Shortness of breath. Sudden shortness of breath may be felt.

In most cases, however, ventricular fibrillation develops suddenly without any warning.

When to Call Emergency Services

Suspicion of ventricular fibrillation is an absolute emergency:

• If the person is unconscious and has no pulse, call emergency services immediately and begin cardiopulmonary resuscitation (CPR).
• If an automated external defibrillator (AED) is available, use it immediately.
• Continue CPR until the ambulance arrives.
• Every second is critical. Intervene immediately.

Causes and Risk Factors

Ventricular fibrillation is usually associated with heart disease or conditions affecting the heart's electrical system.

The most important causes are:

• Heart attack (myocardial infarction). This is the most common cause. Lack of blood flow to the heart muscle during a heart attack can lead to ventricular fibrillation. VF develops within the first hour in approximately 10 percent of those experiencing a heart attack.
• Cardiomyopathy. Diseases of the heart muscle significantly increase VF risk. Dilated cardiomyopathy, hypertrophic cardiomyopathy, and arrhythmogenic right ventricular cardiomyopathy are especially risky.
• Heart failure. VF risk is high in advanced heart failure.
• Previously experienced ventricular fibrillation. Having had VF once greatly increases the risk of recurrence.
• Ventricular tachycardia. Rapid ventricular tachycardia often converts to ventricular fibrillation.
• Long QT syndrome. This is a hereditary disease affecting the heart's electrical system. It can lead to sudden death at a young age.
• Brugada syndrome. This is a genetic heart rhythm disorder. It increases VF risk especially during sleep.
• Hypertrophic cardiomyopathy. Abnormal thickening of the heart muscle is a cause of sudden death in young athletes.
• Heart valve diseases. Aortic valve stenosis in particular increases VF risk.
• Electrolyte imbalance. Severely abnormal levels of potassium, magnesium, or calcium can trigger VF.
• Medications and substances. Some medications (especially those that prolong the QT interval), cocaine, amphetamines, and excessive alcohol increase VF risk.
• Electrical shock. High-voltage electrical shock directly causes VF.
• Drowning and asphyxia. Oxygen deprivation can lead to VF development.
• Commotio cordis. A direct blow to the chest (especially during sports) can trigger VF if it strikes the heart at a critical moment. This is seen in young athletes.
• Hypothermia. Severe drop in body temperature can cause VF.

Complications

Ventricular fibrillation itself is already the most serious complication.

• Sudden cardiac arrest and death. If left untreated, VF leads to death within minutes.
• Brain damage. The brain is rapidly damaged when deprived of oxygen. Permanent brain damage develops after five minutes. Memory loss, cognitive impairment, and neurological problems may be seen.
• Organ damage. The kidneys, liver, and other organs can sustain permanent damage.
• Hypoxic-ischemic encephalopathy. This is severe brain damage resulting from lack of oxygen to the brain. It can lead to coma or vegetative state.
• Post-resuscitation syndrome. Organ failures, infections, and other complications can develop in people who survive after CPR.

Diagnosis

Ventricular fibrillation is an emergency diagnosis and must be made quickly.

• Electrocardiogram (ECG). This confirms the diagnosis. In VF, the ECG shows completely irregular and chaotic waves. No regular QRS complexes are seen. Rapid and irregular oscillations are observed on the monitor.
• Cardiac monitor. Heart rhythm is continuously monitored in the emergency room or ambulance.
• Pulse check. No pulse can be detected.

After VF is diagnosed, the underlying cause is investigated:

• Blood tests. Troponin (heart attack marker), electrolyte levels, kidney and liver functions are checked.
• Echocardiography. Heart function, valve diseases, and structural problems are assessed.
• Coronary angiography. Whether there is blockage in the heart vessels is investigated. Coronary angiography is performed in most people who survive VF.
• Cardiac MRI. Scar tissue and inflammation in the heart muscle are sought.
• Genetic testing. If VF develops at a young age, inherited rhythm disorders are investigated.

Treatment

Ventricular fibrillation requires emergency treatment. Every second is critical.

Emergency treatment:

• Cardiopulmonary resuscitation (CPR). This should be started immediately. Rapid, firm compressions are applied to the center of the chest 100-120 times per minute. The chest should compress at least 5 cm. Trained individuals give 2 breaths after every 30 compressions. Untrained individuals can perform chest compressions only. CPR provides minimal blood flow to the brain and heart and saves lives.
• Defibrillation (electrical shock). This is the most critical intervention. An automated external defibrillator (AED) or manual defibrillator is used. The electrical shock resets the chaotic electrical activity and allows the heart to return to normal rhythm. If the first shock is unsuccessful, CPR is continued and the shock is repeated every 2 minutes. Early defibrillation dramatically increases the chance of survival.
• Advanced life support. This is administered by paramedics or emergency room staff. Intravenous access is established. Medications such as epinephrine and amiodarone are given. Airway security is ensured and respiratory support is provided.
• Treatment of the underlying cause. If there is a heart attack, emergency angiography and stent placement are performed. Electrolyte imbalances are corrected.
• Post-resuscitation care. Survivors are monitored in intensive care. Targeted temperature management (mild hypothermia) can reduce brain damage. Organ functions are supported.

Long-term treatment:

• Implantable cardioverter defibrillator (ICD). An ICD is implanted in almost all people who survive VF. This device is surgically placed below the chest. It continuously monitors heart rhythm. When it detects VF, it automatically delivers a shock and saves lives. The ICD is very effective at preventing recurrent sudden death.
• Medication. Beta blockers or antiarrhythmic medications (amiodarone, sotalol) help reduce VF risk. They are not sufficient alone, however, and are used together with an ICD.
• Catheter ablation. In some cases, abnormal electrical foci that trigger VF can be destroyed with ablation. This method is not appropriate for every patient, however.
• Wearable cardioverter defibrillator (WCD). This provides temporary protection until an ICD can be implanted. It is worn like a vest and delivers automatic shocks when VF is detected.

Prevention

Preventive measures should be taken in people at high risk for ventricular fibrillation.

• ICD implantation. In high-risk patients (previous VF, severe heart failure, hypertrophic cardiomyopathy), an ICD saves lives.
• Control of risk factors. High blood pressure, cholesterol, and diabetes should be brought under control.
• Recognition of heart attack symptoms. If chest pain develops, emergency services should be called immediately. Early intervention reduces VF risk.
• Attention to medications. Medications that prolong the QT interval should be used carefully.
• Maintenance of electrolyte balance. Especially in heart patients, potassium and magnesium levels should be kept normal.
• Family screening. Family members of people with long QT syndrome, Brugada syndrome, or hypertrophic cardiomyopathy should be screened.
• CPR training. Relatives of heart patients should be taught CPR and AED use.
• AED access. Having AEDs in gyms, shopping centers, and public buildings saves lives.

Recovery from Ventricular Fibrillation

People who survive VF are fortunate. The recovery process can be difficult, however.

• Brain function can vary. Most people who receive early resuscitation recover completely. Those with delayed intervention may develop memory problems, concentration difficulties, and cognitive issues.
• If you have an ICD, maintain it. Attend regular cardiology appointments. The ICD battery is replaced after years. If your ICD delivers a shock, be sure to notify your doctor.
• Use your medications regularly. Antiarrhythmic medications, beta blockers, and heart failure medications should be used regularly.
• Get psychological support. VF and resuscitation are traumatic experiences. Anxiety, depression, and post-traumatic stress disorder can develop. Psychological support is beneficial.
• Physical rehabilitation. A cardiac rehabilitation program improves heart function and increases quality of life.
• Driving restrictions. After VF, driving may be restricted for a certain period. Discuss with your doctor.
• Educate your family. Teach your relatives CPR. Explain that they should not panic when the ICD delivers a shock.
• Avoid triggers. Excessive exercise, alcohol, caffeine, and stress can trigger VF. Consult your doctor about restrictions.

Preparing for Your Appointment

For people who have survived VF:

What you can do:

• When and how did VF develop?
• How long were you unconscious?
• How many times was defibrillation performed?
• Was a neurological assessment done?
• Is there a family history of sudden death?
• List all medications you are taking.
• Write your questions down in advance.

Questions you can ask your doctor:

• What was the cause of VF?
• Do I need an ICD?
• What is my risk of recurrence?
• Is there brain damage?
• Can I exercise?
• Can I drive?
• Should my family be screened?
• What is my life expectancy?

Your doctor may ask you:

• Were there warning symptoms before VF?
• Have you had a heart attack before?
• Do you have heart failure?
• Is there a family history of sudden death?
• Is there drug use?
• What medications are you taking?