Ventricular Fibrillation

Cardiology (12%) Core Clinical Conditions

1B: Able to identify the condition as a possible diagnosis: may not have the knowledge or resources to confirm the diagnosis or to manage the condition safely, but can take measures to avoid immediate deterioration and refer appropriately

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Definition Aetiology Pathophysiology Risk factor Sign and Symptoms Investigations Diagnosis Management

Ventricular fibrillation (VF) is a type of cardiac arrhythmia in which the ventricles of the heart quiver chaotically instead of contracting in a coordinated manner. This results in the heart being unable to pump blood effectively, leading to cardiac arrest and loss of consciousness. Ventricular fibrillation is a medical emergency that requires immediate treatment, typically with a defibrillator to shock the heart back into a normal rhythm.

Ventricular fibrillation can be classified into two main categories: ischemic and non-ischemic.

Ischemic causes of ventricular fibrillation include:

• Coronary artery disease

• Myocardial infarction (heart attack)

• Cardiomyopathy

Non-ischemic causes include:

• Hypertrophic cardiomyopathy

• Idiopathic dilated cardiomyopathy

• Structural heart disease

• Electrolyte imbalances (such as low potassium or magnesium levels)

• Certain medications

• Genetic disorders

• Trauma or injury to the heart

• Overheating or heat stroke

• It can also occur as a complication of cardiac surgery or a complication of certain medical procedures such as ablation for atrial fibrillation,

VF is a type of cardiac arrhythmia characterized by rapid, chaotic contractions of the ventricular muscle. In VF, the electrical activity of the heart becomes disorganized, preventing the ventricles from effectively pumping blood to the body. This can lead to cardiac arrest, in which blood flow to the brain and other vital organs is interrupted (see image 1).

• Coronary artery disease

• Heart attack

• Heart failure

• Cardiomyopathies (diseases of the heart muscle)

• Hypertrophic cardiomyopathy (a genetic condition in which the heart muscle becomes thick)

• Valvular heart disease

• Cardiac trauma or injury

• Electrocution

• Drug abuse, particularly cocaine use

• Excessive alcohol consumption

• Inherited arrhythmia syndromes

• Long QT syndrome

• Wolff-Parkinson-White syndrome

• Pulmonary embolism

• Hyperthyroidism

• Anemia

• Dehydration

• Hypoxia

• Electrolyte imbalances

• Certain medications, such as those used to treat heart disease, high blood pressure, and asthma

• Sudden collapse or loss of consciousness

• No pulse or weak pulse

• No breathing or shallow breathing

• Chest pain or discomfort

• Palpitations (irregular, rapid or fluttering heartbeat)

• Dizziness or lightheadedness

• Shortness of breath

• Fatigue

• Electrocardiogram (ECG) to measure the electrical activity of the heart and detect abnormal rhythms (see image 2)

• Blood tests to check for underlying medical conditions or causes of VF such as electrolyte imbalances or heart disease

• Imaging tests such as echocardiography or computed tomography (CT) scans to assess the structure and function of the heart

• Other specialized tests such as an electrophysiology study or cardiac catheterization may also be performed to further evaluate the cause of VF.

Ventricular fibrillation is always diagnosed in an emergency situation. A pulse examination will show no pulse if sudden cardiac death has happened.

 Treatment for ventricular fibrillation (VF) is aimed at restoring a normal heart rhythm as quickly as possible to prevent cardiac arrest and death. The primary treatment for VF is defibrillation, which uses an electrical shock to the heart to stop the chaotic contractions and restore a normal rhythm. This is typically done with an automated external defibrillator (AED) or a manual defibrillator in a hospital setting.

Additional treatments for VF may include:

• Cardiopulmonary resuscitation (CPR) to support circulation and oxygenation of the body until a normal rhythm can be restored

• Anti-arrhythmic drugs such as amiodarone can be used to control the heart rate and rhythm

• Procedures such as coronary artery bypass surgery or angioplasty to treat underlying heart disease that may be contributing to the VF

• Implantation of a pacemaker or an implantable cardioverter-defibrillator (ICD) to prevent future episodes of VF or other abnormal heart rhythms

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