Ventricular fibrillation causes uncoordinated quivering of the ventricle with no useful contractions. It causes immediate syncope and death within minutes. Treatment is with cardiopulmonary resuscitation, including immediate defibrillation.
(See also Overview of Arrhythmias.)
Ventricular fibrillation (VF) is due to multiple wavelet reentrant electrical activity and is manifested on electrocardiogram (ECG) by ultrarapid baseline undulations that are irregular in timing and morphology.
VF is the presenting rhythm for about 70% of patients in cardiac arrest and is thus the terminal event in many disorders. Overall, most patients with VF have an underlying heart disorder (typically ischemic cardiomyopathy, but also hypertrophic cardiomyopathy or dilated cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, or Brugada syndrome). Patients in whom no underlying disorder is detected are considered to have idiopathic VF. Risk of VF in any disorder is increased by electrolyte abnormalities, acidosis, hypoxemia, or ischemia.
Ventricular fibrillation is much less common among infants and children, in whom asystole is the more common presentation of cardiac arrest.
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Image courtesy of L. Brent Mitchell, MD.
Idiopathic ventricular fibrillation
Patients who have been resuscitated from VF cardiac arrest typically are evaluated for cardiac disease, particularly coronary artery disease, cardiomyopathies, and channelopathies. If comprehensive electrocardiographic, imaging, and provocative testing do not identify any such causative disorder, the patient is considered to have idiopathic ventricular fibrillation. It is thought that some of these patients likely have an unrecognized or unknown genetic disorder. Because of the possibility that the disorder is familial, it is recommended that family members have clinical evaluation for possible cardiac events (eg, syncope, palpitations) and limited testing, including ECG, exercise stress testing, and echocardiography. The role of genetic testing is undefined. Treatment is an implantable cardioverter-defibrillator.
Treatment of Ventricular Fibrillation
Defibrillation
Implantable cardioverter-defibrillator
Treatment of ventricular fibrillation is with cardiopulmonary resuscitation, including defibrillation. The success rate for immediate (within 3 minutes) defibrillation is about 95%, provided that overwhelming pump failure does not preexist. When it does, even immediate defibrillation is only 30% successful, and most resuscitated patients die of pump failure before hospital discharge.
Patients who have VF without a reversible or transient cause are at high risk of future VF events and of sudden death. Most of these patients require an implantable cardioverter-defibrillator; many require concomitant antiarrhythmic drugs to reduce the frequency of subsequent episodes of ventricular tachycardia and VF.
