Ventricular Fibrillation Symptoms

Ventricular Fibrillation (V-Fib) occurs when the lower chambers of the heart do not fill with blood, but do not empty. The National Institute of Health (NIH) describes V-fib as twitching or quivering of heart muscle fibers, which renders the heart unable to pump blood to the brain and other organs. Victims of V-Fib quickly become unconscious due to lack of brain oxygenation and are at risk for cardiac arrest. Recognition of ventricular fibrillation symptoms and early treatment of V-Fib are critical for survival.

Chest Pain

During ventricular fibrillation the hearts strays from a normal, strong beat and begins to wiggle or shiver. These uncoordinated movements, as well as reduced oxygen flow to the tissues and muscles, can cause chest pain. Pain may be felt as a heavy weight on the chest, chest discomfort, or pain between the shoulder blades in the upper back. Nausea may accompany chest discomfort, and rest or movement may not make symptoms better. The University of Maryland Medical Center suggests that chest pain, or any symptom of V-Fib, may occur up to one hour before a person becomes unconscious from the condition.

Chest pain especially when combined with dizziness, is an emergency and should prompt a call to 9-1-1. Someone experiencing V-Fib will require treatment with an external defibrillator which shocks the heart from V-Fib into a normal, life-sustaining rhythm. Without defibrillation, the heart will eventually stop altogether.


The brain relies on a continual supply of oxygen in order to function properly. During ventricular fibrillation, the lower chambers of the heart fill, but are unable to be circulated. This results in insufficient, or absent, blood flow to the brain and body. Dizziness is an early sign that the brain is not receiving enough oxygen, which will lead to unconsciousness during a V-Fib episode.

Rapid Pulse

The heart struggles to pump blood during V-Fib, causing the pulse rate to momentarily increase in effort to supply the body with oxygen. The pulse may feel fast and irregular and cause the person experiencing it to feel as if her heart is pounding inside her chest. A rapid pulse may only last for a short time before becoming weak and nearly undetectable as the heart fails and the victim becomes unconscious.

About this Author

Based in Wisconsin, Elizabeth Otto is a licensed emergency medical technician-intermediate with 10 years of experience in the field. She has worked as clinical assistant in family health and emergency medicine since 1995. Otto is a copywriter and freelance writer for She holds an Associate of Science degree in medical assisting from Commonwealth College.