If not immediately treated by defibrillation, fibrillation is usually lethal because all of the heart muscle fibres move independently instead of in the coordinated pulses needed to pump blood and maintain circulation. Above 200 mA, muscle contractions are so strong that the heart muscles cannot move at all, but these conditions prevent fibrillation. Neurological effects
Electrical current can cause interference with nervous control, especially over the heart and lungs. Electric shock which does not lead to death has been shown to cause neuropathy at the site where the current entered the body. The neurologic symptoms of electrical injury may occur immediately, which traditionally have a higher likelihood for healing, though they may also be delayed by days to years. The delayed neurologic consequences of electrical injury have a worse prognosis.When the patch of electrical current proceeds through the head, it appears that, with sufficient current applied, loss of consciousness almost always occurs swiftly. This is borne out by some limited self-experimentation by early designers of the electric chair and by research from the field of animal husbandry, where electric stunning has been extensively studied.If ventricular fibrillation occurs (as above), the blood supply to the brain is diminished, which may cause cerebral hypoxia (and its associated neurologic consequences). Mental health
There are a variety of psychiatric effects that may occur as a result of electrical injuries. Behavioral changes can occur as well, even if the path of electrical current did not proceed through the head.
Shortly thereafter, in 1892, the term was used in Science to refer generically to death or injury caused by electricity. Factors in lethality of electric shock
The lethality of an electric shock is dependent on several variables:

Current. The higher the current, the more likely it is lethal. Since current is proportional to voltage when resistance is fixed (ohms law), high voltage is an indirect risk for producing higher currents. Duration. The longer the duration, the more likely it is lethal—safety switches may limit time of current flow
Pathway. If current flows through the heart muscle, it is more likely to be lethal. High voltage (over about 600 volts). In addition to greater current flow, high voltage may cause dielectric breakdown at the skin, thus lowering skin resistance and allowing further increased current flow. Medical implants. Artificial cardiac pacemakers or implantable cardioverter-defibrillators (ICD) are sensitive to very small currents. Pre-existing medical condition. Age and sex.Other issues affecting lethality are frequency, which is an issue in causing cardiac arrest or muscular spasms. Very high frequency electric current causes tissue burning, but does not penetrate the body far enough to cause cardiac arrest (see electrosurgery). Also important is the pathway: if the current passes through the chest or head, there is an increased chance of death. From a main circuit or power distribution panel the damage is more likely to be internal, leading to cardiac arrest.