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Atrial Fibrillation (AFib) vs. Ventricular Fibrillation (VFib) Causes. Which Is Worse?

What Is Atrial Fibrillation (AFib)?

Patient Comments

Atrial fibrillation (AFib) is a type of abnormal heart rhythm (arrhythmia), usually with a very fast heart rate, that is caused by irregular contractions of the upper chambers of the heart (the atria).

What Is Ventricular Fibrillation (VFib)?

Patient Comments

Ventricular fibrillation (VFib) also is a type of abnormal heart rhythm in which the heart rate that is irregular, and usually fast due to irregular contractions of the lower chambers of the heart (ventricles).

Are AFib and Vfib Caused by the Same Problem?

Atrial fibrillation and ventricular fibrillation are caused by similar problems with the heart, but they are not the same type of problem. Electrical impulses generated within the heart tissue cause both heart conditions, but the electrical impulses arise in different areas of the heart. Irregular electrical impulses occur from multiple sites in the atria to cause atrial fibrillation, while irregular electrical impulses occur mainly in the ventricles to cause ventricular fibrillation.

Which Is Worse, AFib or VFib?

Although both atrial fibrillation and ventricular fibrillation may cause serious medical problems with a patient. Ventricular fibrillation, especially if it is sustained, is considered far more serious as the patient can quickly develop "sudden death" or "cardiac arrest," and die. Ventricular fibrillation does not allow the heart to pump enough blood to the arteries, and therefore to the body's vital organs, because the heart's ventricles are quivering (fibrillation), and they cannot pump blood (contract or squeeze). Ventricular fibrillation is considered a medical emergency.

ECGs and Pictures of AFib vs. VFib

Pictures of a normal and a fibrillating heart, and its electrical activity during atrial fibrillation.

Picture of a Cross Section of the Heart Including the Atria and Ventricles.
Picture of a Cross Section of the Heart Including the Atria and Ventricles.

AFib also is referred to as "supraventricular tachycardia" because the problem occurs above the ventricles. In AFib, the abnormal heart rhythm is due to irregular electrical activity in the atria, mainly the right atrium, and usually it results in a fast and irregular heartbeat.

Picture of a Normal Heart, and a Heart During Atrial Fibrillation

The electrical activity of a normal heart, and a heart during atrial fibrillation.

VFib occurs when the electrical signal is chaotic within the ventricular muscular tissue, which results in no effective heartbeat so there is no effective blood pressure or pulse generated, which results in sudden cardiac death if the person is not treated immediately.

Picture of the Electrical Activity of the Heart during Ventricular Fibrillation.
Picture of the Electrical Activity of the Heart during Ventricular Fibrillation.

ECGs of a normal, atrial fibrillation, and ventricular fibrillation

Normal ECG Wave Pattern Strip of a Normal Heartbeat

Normal ECG Wave Strip Pattern
Normal Heartbeat ECG Wave Strip Pattern

Enlargement of a normal ECG Strip showing PQRST Intervals in a normal heartbeat

Enlargement of a normal ECG Strip showing PQRST Intervals in a normal heartbeat
Enlargement of a normal ECG Strip showing PQRST Intervals in a normal heartbeat

ECG EKG Wave Strip of Atrial Fibrillation

Atrial Fibrillation ECG Wave Strip Pattern
Atrial Fibrillation ECG Wave Strip Pattern

Note in the strip above, AFib ECG irregular waves that separate the QRS complex resulting in an irregular heartbeat seen as the QRS complex spikes.

The following figure shows Vfib with no QRS complex spikes. This means there is no effective ventricular contractions which means the is no heartbeats- the heart muscles of the ventricles just twitch or shake.

ECG Wave Pattern Strip for Atrial  Ventricular Fibrillation

ECG Wave Pattern Strip for Atrial Ventricular Fibrillation

Medically Reviewed by a Doctor on 10/10/2017

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Patient Comments & Reviews

The eMedicineHealth doctors ask about Atrial Fibrillation vs. Ventricular Fibrillation: ECG Differences and Similarities:

AFib vs. VFib - AFib Experience

Please share your experience with atrial fibrillation.

AFib vs. VFib - VFib Experience

Please share your experience with ventricular fibrillation.

AFib vs. VFib - Causes

If known, what caused your atrial or ventricular fibrillation?

AFib vs. VFib - Treatment and Management

Please share what treatment therapies have been helpful in managing your heart condition.

Atrial Fibrillation Warning Symptoms and Signs

Atrial fibrillation or AFib is the most common type of abnormal heart rhythm (arrhythmia). About 2% to 9% of the population in the US have the condition. Could you tell AFib from a heart attack? Warning symptoms of atrial fibrillation are chest pain, shortness of breath, and nausea.

REFERENCE: CDC. "Atrial Fibrillation Fact Sheet." Updated: Aug 22, 2017.

Atrial Fibrillation Slideshow


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