View source for Fibrillation

{{short description|Rapid, irregular contraction of muscle fibers (typically of the heart)}}
{{for|the video game|Fibrillation (video game)}}
{{more citations needed|date=September 2012}}
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'''Fibrillation''' is the rapid, irregular, and unsynchronized [[muscle contraction|contraction]] of [[myocyte|muscle fibers]]. An important occurrence is with regard to the [[heart]].

==Cardiology==
There are two major classes of cardiac fibrillation: [[atrial fibrillation]] and [[ventricular fibrillation]].
* [[Atrial fibrillation]] is an irregular and uncoordinated contraction of the [[cardiac muscle]] of [[atrium (heart)|atria]]. It can be a chronic condition, usually treated with anticoagulation and sometimes with [[cardioversion|conversion]] to [[cardiac pacemaker|normal sinus rhythm]]. In this condition the normal electrical pulses coming from the [[sinoatrial node]] are overwhelmed by disorganized electrical impulses usually originating in the roots of the [[pulmonary veins]], leading to irregular conduction of impulses to the [[Ventricle (heart)|ventricles]] which generate the heartbeat.<ref name="Reddy Taha Kundumadam Khan 2017 pp. 545–550">{{cite journal | last1=Reddy | first1=Vivek | last2=Taha | first2=Wael | last3=Kundumadam | first3=Shanker | last4=Khan | first4=Mazhar | title=Atrial fibrillation and hyperthyroidism: A literature review | journal=Indian Heart Journal | publisher=Elsevier BV | volume=69 | issue=4 | date=2017-07-05 | issn=0019-4832 | pmid=28822529 | pmc=5560908 | doi=10.1016/j.ihj.2017.07.004 | pages=545–550}}</ref><ref name="Dalen Alpert 2017 pp. 264–267">{{cite journal | last1=Dalen | first1=James E. | last2=Alpert | first2=Joseph S. | title=Silent Atrial Fibrillation and Cryptogenic Strokes | journal=The American Journal of Medicine | publisher=Elsevier BV | volume=130 | issue=3 | year=2017 | issn=0002-9343 | pmid=27756556 | doi=10.1016/j.amjmed.2016.09.027 | pages=264–267| doi-access=free }}</ref>
* [[Ventricular fibrillation]] is an irregular and uncoordinated contraction of the cardiac muscle of [[ventricle (heart)|ventricles]]. It is a common cause of [[cardiac arrest]] and is usually fatal if not reversed by [[defibrillation]].<ref name="Visser van der Heijden Doevendans Loh 2016 p. ">{{cite journal | last1=Visser | first1=Marloes | last2=van der Heijden | first2=Jeroen F. | last3=Doevendans | first3=Pieter A. | last4=Loh | first4=Peter | last5=Wilde | first5=Arthur A. | last6=Hassink | first6=Rutger J. | title=Idiopathic Ventricular Fibrillation | journal=Circulation: Arrhythmia and Electrophysiology | publisher=Ovid Technologies (Wolters Kluwer Health) | volume=9 | issue=5 | year=2016 | issn=1941-3149 | pmid=27103090 | doi=10.1161/circep.115.003817 | doi-access=free }}</ref><ref name="Krummen Ho Villongco Hayase 2016 pp. 373–390">{{cite journal | last1=Krummen | first1=David E | last2=Ho | first2=Gordon | last3=Villongco | first3=Christopher T | last4=Hayase | first4=Justin | last5=Schricker | first5=Amir A | title=Ventricular fibrillation: triggers, mechanisms and therapies | journal=Future Cardiology | publisher=Future Medicine Ltd | volume=12 | issue=3 | year=2016 | issn=1479-6678 | pmid=27120223 | doi=10.2217/fca-2016-0001 | pages=373–390}}</ref><ref name="Luo Jin Zhang Huang pp. 19–30">{{cite journal | last1=Luo | first1=Qingzhi | last2=Jin | first2=Qi | last3=Zhang | first3=Ning | last4=Huang | first4=Shangwei | last5=Han | first5=Yanxin | last6=Lin | first6=Changjian | last7=Ling | first7=Tianyou | last8=Chen | first8=Kang | last9=Pan | first9=Wenqi | last10=Wu | first10=Liqun | title=Antifibrillatory effects of renal denervation on ventricular fibrillation in a canine model of pacing-induced heart failure | journal=Experimental Physiology | publisher=Wiley | volume=103 | issue=1 | date=2017-11-28 | issn=0958-0670 | pmid=29094471 | doi=10.1113/ep086472 | pages=19–30| doi-access=free }}</ref><ref name="Ludhwani Jagtap 2018">{{cite journal | last1=Ludhwani | first1=Dipesh | last2=Jagtap | first2=Mandar | title=Rhythm, Ventricular Fibrillation | website=NCBI Bookshelf | date=2018-12-19 | pmid=30725805 | url=https://www.ncbi.nlm.nih.gov/books/NBK537120/ | access-date=2019-03-29}}</ref>

Fibrillation may sometimes be used after heart surgery to stop the heart from beating while any minor leaks are stitched up.

==Musculoskeletal==
Fibrillation also occurs with individual skeletal muscle fibers.<ref>{{DorlandsDict|three/000039912|fibrillation}}</ref> This happens when muscle fibers lose contact with their innervating axon producing a spontaneous action potential, "fibrillation potential" that results in the muscle fiber's contraction. These contractions are not visible under the skin and are detectable through needle [[electromyography]] (EMG) and ultrasound.<ref>{{cite journal |vauthors=Pillen S, Nienhuis M, van Dijk JP, Arts IM, van Alfen N, Zwarts MJ | year = 2009 | title = Muscles alive: ultrasound detects fibrillations | journal = Clin Neurophysiol | volume = 120 | issue = 5| pages = 932–6 | doi = 10.1016/j.clinph.2009.01.016 | pmid = 19356976 | s2cid = 7201008 }}</ref>  Fibrillations can occur in healthy individuals. If the fibrillations have irregular potentials, then they don't have pathological significance.<ref>{{cite journal | pmc = 492832 | pmid=925696 | volume=40 | issue=8 | title=Benign fibrillation potentials in normal muscle and their correlation with endplate and denervation potentials | year=1977 | journal=J. Neurol. Neurosurg. Psychiatry | pages=765–8 | author=Stöhr M | doi=10.1136/jnnp.40.8.765}}</ref> In other cases they are a major symptom in acute and severe peripheral nerve disorders, in myopathies in which muscle fibers are split or inflamed, and in [[lower motor neuron lesion]]s.

They contrast with [[fasciculations]] that are ''visible'' spontaneous contractions involving ''small groups'' of muscle fibers.  Fasciculations can be seen in lower motor neuron lesions as well, but they also do not necessarily denote pathology.

==Terminology==
The word ''fibrillation'' ({{IPAc-en|ˌ|f|ɪ|b|r|ᵻ|l|ˈ|eɪ|ʃ|ən}}) is related to the word ''[[fibril]]'' in the sense of [[myofibril|muscle fibrils]], the [[protein]]s that make up each [[myocyte|muscle fiber]] (muscle cell).

==References==
{{reflist}}

{{Heart diseases}}
{{Nervous and musculoskeletal system symptoms and signs}}

[[Category:Cardiac arrhythmia]]
[[Category:Symptoms and signs: Nervous system]]