Atrial fibrillation is an irregular and uncoordinated contraction of thecardiac muscle ofatria. It can be a chronic condition, usually treated with anticoagulation and sometimes withconversion tonormal sinus rhythm. In this condition the normal electrical pulses coming from thesinoatrial node are overwhelmed by disorganized electrical impulses usually originating in the roots of thepulmonary veins, leading to irregular conduction of impulses to theventricles which generate the heartbeat.[1][2]
Fibrillation also occurs with individual skeletal muscle fibers.[7] 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 needleelectromyography (EMG) and ultrasound.[8] Fibrillations can occur in healthy individuals. If the fibrillations have irregular potentials, then they don't have pathological significance.[9] 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 inlower motor neuron lesions.
They contrast withfasciculations that arevisible spontaneous contractions involvingsmall groups of muscle fibers. Fasciculations can be seen in lower motor neuron lesions as well, but they also do not necessarily denote pathology.
^Krummen, David E; Ho, Gordon; Villongco, Christopher T; Hayase, Justin; Schricker, Amir A (2016). "Ventricular fibrillation: triggers, mechanisms and therapies".Future Cardiology.12 (3). Future Medicine Ltd:373–390.doi:10.2217/fca-2016-0001.ISSN1479-6678.PMID27120223.
