Overview

Ventricular fibrillation (VF) is a life-threatening cardiac arrhythmia characterized by rapid, erratic electrical impulses in the ventricles of the heart. This chaotic electrical activity causes the ventricles to quiver ineffectively rather than contract in a coordinated manner, leading to a sudden and complete loss of cardiac output. Without immediate medical intervention, VF results in sudden cardiac arrest and death within minutes. It is a leading cause of sudden cardiac death (SCD) worldwide and is considered a medical emergency requiring prompt defibrillation and advanced cardiac life support.

Causes

Ventricular fibrillation usually occurs in the context of existing heart disease or electrical instability in the heart. Common causes include:

• Coronary Artery Disease (CAD): The most frequent cause of VF, especially following a heart attack (myocardial infarction), due to reduced blood flow to the heart muscle.
• Cardiomyopathy: Diseases that damage the heart muscle, such as dilated or hypertrophic cardiomyopathy, can increase the risk of VF.
• Heart Attack: Acute myocardial infarction can precipitate VF, particularly in the early stages.
• Electrolyte Imbalances: Abnormal levels of potassium, magnesium, or calcium can trigger dangerous arrhythmias.
• Congenital Heart Disorders: Genetic conditions such as long QT syndrome, Brugada syndrome, or other channelopathies can predispose individuals to VF.
• Severe Heart Failure: Weak or damaged heart muscle increases the likelihood of ventricular arrhythmias.
• Drug Toxicity: Certain medications, especially those that prolong the QT interval or recreational drugs like cocaine, can induce VF.
• Electrical Shock: High-voltage electrical injuries can disrupt normal cardiac rhythm and cause VF.
• Trauma: Severe chest trauma (commotio cordis) can directly trigger VF, especially in young athletes.

Symptoms

Ventricular fibrillation presents abruptly, with symptoms reflecting sudden cessation of effective heart function:

• Sudden Collapse: The hallmark feature of VF is sudden loss of consciousness and collapse.
• No Pulse: Upon physical examination, there is no palpable pulse because the heart fails to pump blood effectively.
• Absence of Breathing: Breathing quickly ceases or becomes abnormal (agonal respirations) after cardiac arrest.
• Chest Pain (Prior to Arrest): In some cases, individuals may experience chest pain, palpitations, or dizziness shortly before collapse.
• Sudden Cardiac Death: If untreated, VF rapidly leads to death within minutes due to lack of circulation to vital organs.

Diagnosis

Diagnosis of ventricular fibrillation is made rapidly in emergency settings and involves:

• Electrocardiogram (ECG): VF is characterized by chaotic, irregular waveforms without identifiable QRS complexes, P waves, or T waves.
• Physical Examination: Unconsciousness, absence of pulse, and apnea are clinical signs suggestive of VF.
• Cardiac Monitoring: Continuous cardiac monitoring in hospital settings can capture episodes of VF in high-risk patients.
• Automated External Defibrillator (AED): AED devices used in community settings can diagnose VF and deliver a shock if detected.

Treatment

Immediate treatment is critical for survival in ventricular fibrillation. The primary goal is rapid restoration of an effective heartbeat:

Emergency Treatment

• Defibrillation: Immediate delivery of an electric shock via a defibrillator is the definitive treatment to terminate VF and restore normal rhythm. Early defibrillation dramatically improves survival chances.
• Cardiopulmonary Resuscitation (CPR): High-quality chest compressions are initiated immediately to maintain blood flow to vital organs until defibrillation can be performed.
• Advanced Cardiac Life Support (ACLS): Administering medications such as epinephrine and amiodarone, establishing airway management, and addressing reversible causes during resuscitation efforts.

Post-Resuscitation Care

• Intensive Monitoring: After resuscitation, patients are admitted to intensive care for continuous monitoring and stabilization.
• Treating Underlying Cause: Management of coronary artery disease, electrolyte abnormalities, or heart failure to prevent recurrence.
• Coronary Intervention: Angioplasty or stenting may be performed if VF was due to a heart attack.

Long-Term Treatment

• Implantable Cardioverter Defibrillator (ICD): Patients at high risk of recurrent VF often receive an ICD, a device implanted under the skin that can detect and correct life-threatening arrhythmias automatically.
• Medications: Anti-arrhythmic drugs like beta-blockers, amiodarone, or sotalol may be used to reduce arrhythmia risk.
• Lifestyle Changes: Heart-healthy diet, regular exercise, smoking cessation, and control of underlying conditions are crucial in preventing recurrence.

Prognosis

The prognosis of ventricular fibrillation depends heavily on the speed of treatment. If defibrillation and CPR are performed within the first few minutes of cardiac arrest, survival rates can be as high as 60-70%. However, every minute of delay significantly reduces survival chances. Without treatment, VF is uniformly fatal within minutes.

Individuals who survive an initial VF episode often require long-term management, including ICD implantation and treatment of the underlying cardiac condition. With appropriate medical care, many patients can resume normal daily activities, although they remain at higher risk of recurrent arrhythmias. Early intervention, rapid defibrillation, and comprehensive follow-up care are key to improving outcomes and survival in ventricular fibrillation.