Ventricular fibrillation


Ventricular fibrillation, often referred to as VFib, Vfib, or VF, is a form of irregular heart rhythm known as an arrhythmia. This condition involves the rapid and uncoordinated contraction of the lower chambers of the heart, leading to an inadequate pumping of blood throughout the body. Ventricular fibrillation is a medical emergency that demands immediate attention and is the leading cause of sudden cardiac death. 

During ventricular fibrillation, the lower heart chambers quiver or twitch instead of contracting and expanding properly, which disrupts the normal bloodpumping function. 

Emergency treatment for ventricular fibrillation typically involves cardiopulmonary resuscitation (CPR) and the application of electrical shocks to the heart using a device called an automated external defibrillator (AED). In some cases, healthcare professionals may recommend medications, implanted medical devices, or surgical procedures to prevent future episodes of ventricular fibrillation. 


The most common symptoms of ventricular fibrillation are collapse and a loss of consciousness. Prior to experiencing a ventricular fibrillation episode, individuals may exhibit signs of an irregularly fast or erratic heartbeat, known as arrhythmia, which can include: 

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

If you are experiencing an unexplained fast or pounding heartbeat, it is advisable to schedule an appointment with a cardiologist. 

In the event you witness someone collapsing due to a potential cardiac emergency, it is crucial to seek immediate medical assistance by following these steps: 

  • Dial your local emergency number. 
  • If the person is unconscious, check for a pulse. 
  • If no pulse is detected, initiate cardiopulmonary resuscitation (CPR) to maintain blood circulation until an automated external defibrillator (AED) becomes available. The American Heart Association recommends handsonly CPR, involving forceful and rapid chest compressions at a rate of about 100 to 120 compressions per minute. There is no need to check the person’s airway or administer rescue breaths. Continue CPR until professional medical help arrives. 
  • As soon as an automated external defibrillator (AED) is accessible, follow its prompts to deliver a shock if indicated by the device’s instructions. 


Ventricular fibrillation can be caused by several factors: 

  • Heart’s electrical problems: One common cause of ventricular fibrillation is a malfunction in the heart’s electrical system. 
  • Disruption of blood aupply: Another cause can be a disruption in the blood supply to the heart muscle. 
  • Unknown causes: Sometimes, ventricular fibrillation occurs without a known cause.

The Heartbeat Process 

The heart comprises four chambers: two upper atria and two lower ventricles. Within the right atrium, the sinus node serves as the heart’s natural pacemaker, initiating each heartbeat. Electrical signals from the sinus node traverse the atria, causing them to contract and pump blood into the ventricles. These signals then reach the atrioventricular (AV) node, slowing down briefly to allow the ventricles to fill with blood. Once they reach the ventricles, the lower chambers contract, propelling blood to the lungs or the rest of the body. In a healthy heart, this process results in a resting heart rate of 60 to 100 beats per minute. However, in ventricular fibrillation, rapid and irregular electrical signals cause the ventricles to quiver ineffectively rather than pump blood. 

Risk factors 

Factors that may increase the risk of experiencing ventricular fibrillation include: 

  • A history of previous ventricular fibrillation episodes. 
  • A previous heart attack. 
  • Congenital heart defects present from birth. 
  • Cardiomyopathy, a heart muscle disease. 
  • Heart muscle injuries due to events such as lightning strikes. 
  • Substance abuse, especially involving cocaine or methamphetamine.
  • Significant imbalances in potassium or magnesium levels.