Ventricular fibrillation occurs in the ventricles (lower chambers) of the heart; it is always a medical emergency. If left untreated, ventricular fibrillation (VF, or V-fib) can lead to death within minutes. When a heart goes into V-fib, effective pumping of the blood stops. V-fib is considered a form of cardiac arrest. An affected individual will not survive unless cardiopulmonary resuscitation (CPR) and defibrillation are provided immediately.CPR can prolong the survival of the brain in the lack of a normal pulse, but defibrillation is the only intervention that can restore a healthy heart rhythm. Defibrillation is performed by applying an electric shock to the heart, which resets the cells, permitting a normal beat to re-establish itself. Triggered beats
Triggered beats occur when problems at the level of the ion channels in individual heart cells result in abnormal propagation of electrical activity and can lead to a sustained abnormal rhythm. They are relatively rare and can result from the action of anti-arrhythmic drugs, or after depolarizations. Management
The method of cardiac rhythm management depends firstly on whether the affected person is stable or unstable. Treatments may include physical maneuvers, medications, electricity conversion, or electro- or cryo-cautery.In the United States, people admitted to the hospital with cardiac arrhythmia and conduction disorders with and without complications were admitted to the intensive care unit more than half the time in 2011. Physical maneuvers
Several physical acts can increase parasympathetic nervous supply to the heart, resulting in blocking of electrical conduction through the AV node.
Differential diagnosis
Normal electrical activity
Each heartbeat originates as an electrical impulse from a small area of tissue in the right atrium of the heart called the sinus node or sinoatrial node (SA node). The impulse initially causes both atria to contract, then activates the atrioventricular node (AV node), which is normally the only electrical connection between the atria and the ventricles (main pumping chambers). The impulse then spreads through both ventricles via the bundle of His and the Purkinje fibers causing a synchronized contraction of the heart muscle and, thus, the pulse.In adults, the normal resting heart rate ranges from 60 to 90 beats per minute. The resting heart rate in children is much faster. In athletes, however, the resting heart rate can be as slow as 40 beats per minute, and be considered normal.The term sinus arrhythmia refers to a normal phenomenon of alternating mild acceleration and slowing of the heart rate that occurs with breathing in and out respectively. It is usually quite pronounced in children and steadily decreases with age. This can also be present during meditation breathing exercises that involve deep inhaling and breath holding patterns. Bradycardias
A slow rhythm (less than 60 beats/min) is labelled bradycardia. This may be caused by a slowed signal from the sinus node (sinus bradycardia), by a pause in the normal activity of the sinus node (sinus arrest), or by blocking of the electrical impulse on its way from the atria to the ventricles (AV block or heart block). Heart block comes in varying degrees and severity.