Editing Ventricular fibrillation (section)

==Signs and symptoms==
Ventricular fibrillation is a cause of [[cardiac arrest]]. The ventricular muscle twitches randomly rather than contracting in a coordinated fashion (from the apex of the heart to the outflow of the ventricles), and so the [[ventricle (heart)|ventricle]]s fail to pump blood around the body – because of this, it is classified as a [[cardiac arrest]] rhythm, and patients in V-fib should be treated with [[cardiopulmonary resuscitation]] (CPR) and prompt [[defibrillation]]. Left untreated, ventricular fibrillation is rapidly fatal as the vital organs of the body, including the heart, are starved of oxygen. As a result, patients in this rhythm will not be conscious or responsive to stimuli. [[Coma]] and [[persistent vegetative state]] may also result. Prior to cardiac arrest, patients may complain of varying symptoms depending on the underlying [[#Causes|cause]]. Patients may exhibit signs of [[agonal breathing]], which to a layperson can look like normal spontaneous breathing, but is a sign of [[Shock (circulatory)|hypoperfusion]] of the [[brainstem]].{{citation needed|date=February 2021}}

It has an appearance on [[electrocardiography]] of irregular electrical activity with no discernable pattern. It may be described as "coarse" or "fine" depending on its amplitude, or as progressing from coarse to fine V-fib. Coarse V-fib may be more responsive to defibrillation, while fine V-fib can mimic the appearance of [[asystole]] on a [[defibrillator]] or [[cardiac monitor]] set to a low [[Gain (electronics)|gain]].  Some clinicians may attempt to defibrillate fine V-fib in the hope that it can be reverted to a [[cardiac rhythm]] compatible with life, whereas others will deliver [[cardiopulmonary resuscitation|CPR]] and sometimes [[drug]]s as described in the [[advanced cardiac life support]] protocols in an attempt to increase its amplitude and the odds of successful defibrillation.{{citation needed|date=February 2021}}