Ventricular fibrillation (VF) is a life-threatening condition in which the heart ceases to beat effectively and instead “quivers” or fibrillates very rapidly – sometimes at 350 beats per minute or more. A person cannot survive this condition for more than a few minutes without emergency treatment. 

Most cases of ventricular fibrillation occur as a result of heart attacks. The person collapses or faints when the heart fibrillation interrupts flow of blood to the brain. However, ventricular fibrillation can also be caused by other forms of heart disease (e.g., heart failure) and heart rhythm disorders, or arrhythmias. A person experiencing ventricular fibrillation must be treated immediately to avoid sudden cardiac death. The treatment for ventricular fibrillation involves shocking the heart back into a normal rhythm with a defibrillator (either a manual defibrillator or an automatic external defibrillator). Giving someone cardiopulmonary resuscitation (CPR) may give him or her some extra time, but defibrillation is essential for surviving ventricular fibrillation. If defibrillation is administered fast enough, and the heart rhythm is restored to normal, the person is said to have experienced aborted sudden cardiac death.

Medical personnel can easily identify VF with their monitoring equipment and can quickly use a defibrillator to shock the heart back to its normal rhythm. However, the time it takes for medical help to arrive may be critical. Success is generally measured in minutes until treatment. People who experience VF outside a hospital setting have poor survival rates. For survivors, treatments to avoid future cases of VF may include either a wearable or implantable defibrillator, which can detect the abnormal rhythm and shock the heart immediately. Others may receive antiarrhythmia medications.

Because most cases of ventricular fibrillation are caused by heart attack, the most reliable warning sign of an impending episode is the heart attack itself. However, in rare cases, ventricular fibrillation may occur among people with healthy hearts or undiagnosed or familial heart disease. It is estimated that idiopathic ventricular fibrillation, which occurs in a person with an otherwise healthy heart, accounts for only about 5 percent of cases of sudden cardiac death. Unfortunately, ventricular fibrillation tends to produce few warning signs by itself. Some patients report changes in the hour or so before the attack, and many patients who experience ventricular fibrillation not related to a heart attack have a history of fainting. However, this lack of symptoms makes the condition difficult to prevent.

Ventricular fibrillation (VF) is a life-threatening type of abnormal heart rhythm (arrhythmia) in which the heart “quivers” rather than beats, sometimes at a rate of 350 beats per minute or more. As a result, adequate blood flow throughout the heart and the rest of the body is drastically reduced. VF is a cardiac emergency that requires a rapid response. Studies have shown that a person cannot survive more than about four minutes in ventricular fibrillation without suffering serious, long-term organ damage or dying. 

People suffering from VF need to be treated with a defibrillator to jolt the heart back into a normal rhythm. CPR (cardiopulmonary resuscitation) also helps by providing oxygen to the lungs and brain while the heart is not pumping. CPR should be given until emergency help arrives and a defibrillator is used. If treatment is not given in time, the heart will completely stop (cardiac arrest) and sudden cardiac death will result.

Although estimates vary widely, VF is considered the leading cause of sudden cardiac death in the United States. In most of those cases, the person suffers from coronary artery disease that may or not have already resulted in a heart attack. In many cases, VF occurs with 48 hours of a heart attack. However, VF leading to sudden cardiac death can also be caused by other forms of heart disease, including cardiomyopathy, myocarditis, arrhythmogenic right ventricular dysplasia and various forms of congenital heart disease. The National Institutes of Health estimates that sudden cardiac death affects nearly 300,000 people each year in the United States.

Despite its name, sudden cardiac death may not always be fatal if help can be rendered immediately. In recent years, survival rates have improved as the use of bystander CPR has increased and the time between collapse and defibrillation has decreased. Survival rates, however, remain poor among people who suffer from sudden cardiac death outside of a hospital setting. Among those who survive, long-term medication or other therapies are usually necessary, and they remain at risk for recurrent VF and sudden cardiac death.

Two other types of arrhythmias are associated with the ventricles. Premature ventricular complex occurs when an abnormal signal from the ventricle prompts an early heartbeat. Ventricular tachycardia is a fast heartbeat caused by electrical signals that begin in the ventricles instead of in the atria. Ventricular tachycardia can lead to VF if left untreated.

Atrial fibrillation (AF) is also a type of arrhythmia that results in a fast and very irregular heartbeat. However, AF differs from VF. It is not life threatening and may not produce any noticeable symptoms. The only condition in which AF can result in ventricular fibrillation is when it is associated with accessory pathway (Wolf-Parkinson-White syndrome).

Most cases of ventricular fibrillation (VF) are caused by a heart attack. A blockage in a coronary artery reduces blood flow to the heart and causes the heart attack. If the VF occurs within 48 hours of the original heart attack, it is known as primary ventricular fibrillation. Other known causes include low blood pressure and shock, an electrical shock to the body and conditions that change the electrical activity in the heart, such as low potassium levels or some drugs.

Knowing the most common risk factors for ventricular fibrillation (VF) can be helpful in preventing or recognizing symptoms before an episode occurs. These risk factors, which can be identified over time, include:

• Coronary artery disease
  
  
• Certain types of congenital heart disease
  
  
• Cardiomyopathy (enlargement of the heart muscle)
  
  
• Arrhythmogenic right ventricular dysplasia
  
  
• Family history of either VF or unexplained fainting (syncope)
  
  
• Long QT syndrome (rare, inherited disorder that affects the heart’s electrical system)
  
  
• Brugada Syndrome (rare genetic cause of sudden unexplained ventricular fibrillation)
  
  
• Electrolyte imbalance in the blood (often caused by low levels of potassium and magnesium)
  
  
• Excessive toxins, such as alcohol or recreational drugs (e.g., cocaine)
  
  
• Overuse of caffeine or decongestants
  
  
• Valve dysfunction
  
  
• Electric shock

Cases of ventricular fibrillation (VF) are a medical emergency and are easily diagnosed by medical personnel with monitoring equipment. People who are at risk for VF but have not suffered an episode yet may be more difficult to diagnose. There There are a number of conditions that predispose people to VF and sudden cardiac death, especially a history of heart attack and coronary artery disease. A physician suspecting one of these conditions might conduct a number of tests to look for certain signs. These tests include: 

• During a medical examination, a physician can detect abnormal heart rhythms (arrhythmia) by listening to the heart with a stethoscope. Blood pressure may also be measured.
  
  
• Blood tests can check blood oxygen levels, electrolytes and hormone levels.
  
  
• Chest x-rays can reveal various abnormalities, including heart enlargement (hypertrophy) and lung dysfunction.
  
  
• An electrocardiogram (EKG) is often considered the best diagnostic tool when VF or any other type of arrhythmia is suspected. An EKG is a recording of the heart’s electrical activity as a graph on a moving strip of paper or video monitor. The highly sensitive electrocardiograph machine helps detect heart irregularities, disease and damage by measuring the heart’s rhythms and electrical activity at rest or while exercising (stress test). EKGs can be done by a physician in an office or hospital setting, or by a portable unit worn by the patient and measured over time (e.g., a Holter monitor or an event recorder).
  
  
• Echocardiogram. This test uses sound waves to visualize the structure and function of the heart. A moving image of the patient’s beating heart is played on a video screen, where a physician can study the heart’s thickness, size and function. The image also shows the motion pattern and structure of the four heart valves, revealing any potential leakage (regurgitation) or narrowing (stenosis). During this test, a Doppler ultrasound may be used to evaluate blood flow.
  
  
• Cardiac catheterization procedures may also be used to help a physician learn more about a patient’s specific arrhythmia. One such test, called an electrophysiology study (EPS), involves placing an electrode catheter into a blood vessel and feeding it all the way to the heart. Once in place, the heart sounds are recorded to find any irregular heart rhythms. This helps the physician to locate the exact origin and nature of an arrhythmia. The physician can also use the electrode to stimulate an arrhythmia to see how helpful medical treatments have been.

The tests used will depend on a number of factors, including the specific symptoms of a patient as well as his or her personal and family medical history.

Because ventricular fibrillation (VF) is a true cardiac emergency, immediate and appropriate treatment is crucial. Every minute counts to avoid sudden cardiac death. The best treatment for the patient is called defibrillation. Defibrillation involves an electrical shock that is given to either “reset” the heart's rhythm, or to “restart” the heart of a patient who has gone into cardiac arrest. Recent studies suggest that the survival rate for VF is as high as 90 percent if defibrillation occurs within one minute of onset. With each minute that passes, the chance for survival decreases by 10 percent. At four minutes, serious damage begins to occur in vital organs, including the brain, and the risk of long-term disability increases dramatically.

There are two strategies for using defibrillation in an emergency. If the patient is in the hospital, physicians can program a manual defibrillator to deliver high intensity electrical charges through two paddles placed on the patient’s chest, restoring normal heart rhythm and restarting the flow of blood.

In a non-medical location like a mall or at home, an automatic external defibrillator (AED) can be used. People do not need any medical training to use AEDs, and their widespread use is recommended by the American Heart Association (AHA). 

AEDs are becoming more common in ambulances and fire rescue vehicles, as well as in places that are cut off from traditional emergency assistance (e.g., airplanes). AEDs are also available in some public gathering places, such as stadiums, shopping malls and golf courses, and have been approved for home use. AEDs can be used on both adults and children.

Giving cardiopulmonary resuscitation (CPR) is one way to “buy time” for someone experiencing VF. CPR can provide oxygen to organs, but it cannot restore the heart rhythm of the patient. Defibrillation can. The AHA recommends immediate CPR, with the first shock by an AED within three to five minutes.

Treatments are available for people who have survived ventricular fibrillation (VF) or cardiac arrest. These treatments may involve controlling an underlying condition such as high blood pressure (hypertension) or coronary artery disease.

In almost all cases, patients who have survived a cardiac arrest require cardiac catheterization and an electrophysiology study. In addition, the most common long-term treatment is implantation of an implantable cardioverter defibrillator (ICD) in the patient’s chest. This device monitors the patient’s heart rhythm and, if necessary, can administer a shock to correct abnormal rhythms.

Medications such as antiarrhythmics may also be prescribed. These medications must be monitored carefully to detect any side effects, which can include increased or worsened arrhythmias. Patients on such medications are advised to become familiar with taking their own pulse, so that any abnormal rhythm will be promptly discovered.

Older and sicker patients tend to benefit the most from ICD implantation. For individuals recovering from a heart attack, a temporary, nonimplanted type of defibrillator may be recommended in order to reduce the heightened risk of sudden cardiac death due to ventricular fibrillation and other arrhythmias.

The wearable cardioverter defibrillator (WCD), approved by the U.S. Food and Drug Administration in 2001, fits over the shoulders and chest and looks a bit like a gun holster. Sensors lead from the area of the heart to a small, battery-operated defibrillator worn on a belt. As with the ICD, the wearable version detects the arrhythmia and then shocks the heart into resuming a normal rhythm.

Many cases of ventricular fibrillation (VF) cannot be prevented. Knowing the most common risk factors for VF can be helpful in preventing or recognizing symptoms before an episode occurs. If someone experiences what feels like a flutter, skipped beat or any other unusual cardiac activity, a medical opinion and diagnosis should be sought. Any unexplained fainting (syncope) incident should prompt immediate medical emergency treatment. With appropriate treatment, many patients who have experienced VF can go on to live normal, healthy lives.

If a person has family members that experienced a sudden death syndrome, they should be thoroughly investigated for familial causes of ventricular fibrillation. This may involve an electrocardiogram and other testing including genetic tests.

Preparing questions in advance can help patients have more meaningful conversations with their physicians about their conditions. Patients may wish to ask their doctors the following questions related to ventricular fibrillation (VF):

1. Are heart palpitations ventricular fibrillations? Can I tell the difference?
   
   
2. I have been diagnosed with atrial fibrillation. Can this become ventricular fibrillation?
   
   
3. Can I observe my spouse for signs of ventricular fibrillation?
   
   
4. I had a case of VF during a heart attack. Will it happen again if I have another heart attack?
   
   
5. After a case of VF, I got an implantable defibrillator. Are there incidents of VF that it will not affect?
   
   
6. How can I tell if my implantable defibrillator is working?
   
   
7. Are any of my heart disease symptoms indicative of the potential for VF?
   
   
8. My spouse had a case of VF and survived. Should we buy a home version of an automatic external defibrillator?
   
   
9. What are the chances that a person who experienced one VF attack will have another?
   
   
10. Does VF run in families? Is there any way to tell if sudden deaths in my family were related to VF?
    
    
11. How common are fibrillation problems with my antiarrhythmia medications?