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Ventricular fibrillation

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Overview  

Ventricular fibrillation, often referred to as VFib, V–fib, 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 blood–pumping 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. 

Symptoms  

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 hands–only 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. 

Causes  

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. 

Diagnosis  

Ventricular fibrillation is typically diagnosed in emergency situations, and if sudden cardiac death has occurred, a pulse check will confirm the absence of a pulse. 

To diagnose and identify the underlying cause of ventricular fibrillation, several diagnostic tests are available: 

  • Electrocardiogram (ECG or EKG): This painless and rapid test measures the heart’s electrical activity. Electrodes are attached to the chest and sometimes the arms and legs, with wires connecting them to a computer that displays the results. An ECG can reveal irregular heart rhythms, such as ventricular fibrillation, which typically manifests as a rapid heartbeat, around 300 to 400 beats per minute. 
  • Blood tests: Blood tests are conducted to assess the presence of cardiac enzymes or proteins that may leak into the bloodstream due to heart damage caused by events like a heart attack. 
  • Chest X–ray: An X–ray of the chest provides images that depict the heart’s size, shape, and the condition of its blood vessels. 
  • Echocardiogram: This non–invasive procedure employs sound waves to create moving images of the heart, enabling assessment of its size and structure. 
  • Cardiac computerized tomography (CT): A CT scan employs X–rays to generate cross–sectional images of specific areas of the body, including the heart. 
  • Cardiac magnetic resonance imaging (MRI): This imaging technique utilizes a magnetic field and radio waves to produce detailed images, especially useful for assessing blood flow within the heart. 
  • Coronary catheterization (Angiogram): This test helps healthcare professionals detect blockages in the coronary arteries. It involves the insertion of a flexible catheter into a blood vessel, often in the groin or wrist, which is then guided to the heart. Dye is injected through the catheter to enhance visibility of the heart’s arteries on X–ray images and videos. 

Treatment  

Ventricular fibrillation is a serious heart condition that requires immediate medical attention to prevent sudden cardiac death. The main goal of emergency treatment is to restore blood flow as quickly as possible and prevent damage to vital organs and the brain. 

Emergency treatment for ventricular fibrillation involves the following steps: 

  • Call for help: Dial your local emergency number right away. 
  • Start CPR (Cardiopulmonary Resuscitation): CPR helps keep blood flowing through the body when the heart is not pumping effectively. Here’s what to do: 
    • Place the heel of your hand on the center of the person’s chest. 
    • Push hard and fast, aiming for about 100 to 120 compressions per minute. 
    • Allow the chest to fully rise between compressions. 
    • Continue CPR until an automated external defibrillator (AED) is available or emergency medical help arrives. 
  • Use an AED (automated external defibrillator): AEDs are devices that can restore a normal heart rhythm by delivering an electrical shock to the heart. Here’s how to use one: 
    • As soon as an AED is available, apply it to the person’s chest and follow the prompts. 
    • If you’re not trained to use an AED, an emergency responder can guide you through the process. 
    • AEDs are designed to recognize ventricular fibrillation and deliver a shock only when necessary. 

In addition to emergency treatment, there are other treatments to prevent future episodes of ventricular fibrillation and reduce the risk of related symptoms. These treatments include: 

Medications

Your doctor may prescribe medications, known as anti–arrhythmics, to help control your heart rhythm and reduce the risk of ventricular fibrillation if you are at risk. 

Medical Devices 

  • Implantable Cardioverter–Defibrillator (ICD): This device, similar to a pacemaker, is implanted under the skin near the collarbone. It continuously monitors your heart rhythm and can deliver shocks to stop ventricular fibrillation and restore a normal rhythm. 

Surgical Procedures 

  • Cardiac ablation: During this procedure, heat or cold energy is used to create small scars in the heart to block irregular electrical signals that can trigger ventricular fibrillation. This is often done with catheters inserted through blood vessels. 
  • Coronary angioplasty and stent placement: If ventricular fibrillation is caused by a heart attack, this procedure can help reduce the risk of future episodes. It involves inflating a balloon in a blocked artery and placing a stent to keep it open.
  • Coronary bypass surgery: In cases where coronary artery disease is the cause of ventricular fibrillation, bypass surgery can redirect blood flow around blocked arteries. A healthy blood vessel is used to create a new pathway for blood circulation. 

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Diseases & Conditions Ventricular fibrillation