Fibrillation
Encyclopedia
Fibrillation is the rapid, irregular, and unsynchronized contraction of muscle fibers. An important occurrence is with regards to the heart
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and ventricular fibrillation
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Fibrillation may sometimes be used after heart surgery to stop the heart from beating while any minor leaks are stitched up.
(EMG) and ultrasound. Fibrillations do not occur in healthy individuals. They are a major symptom in acute and severe peripheral nerve disorders, in myopathies in which muscle fibers are split or inflammed, and lower motor neuron lesions.
They contrast with fasciculations that are visible spontaneous contractions involving small groups of muscle fibers. Also, fasciculation does not necessarily denote pathology, as does fibrillation, although it can be seen in lower motor neuron lesions as well.
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
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Cardiology
There are two major classes of cardiac fibrillation: atrial fibrillationAtrial fibrillation
Atrial fibrillation is the most common cardiac arrhythmia . It is a common cause of irregular heart beat, identified clinically by taking a pulse. Chaotic electrical activity in the two upper chambers of the heart result in the muscle fibrillating , instead of achieving coordinated contraction...
and ventricular fibrillation
Ventricular fibrillation
Ventricular fibrillation is a condition in which there is uncoordinated contraction of the cardiac muscle of the ventricles in the heart, making them quiver rather than contract properly. Ventricular fibrillation is a medical emergency and most commonly identified arrythmia in cardiac arrest...
.
- Atrial fibrillationAtrial fibrillationAtrial fibrillation is the most common cardiac arrhythmia . It is a common cause of irregular heart beat, identified clinically by taking a pulse. Chaotic electrical activity in the two upper chambers of the heart result in the muscle fibrillating , instead of achieving coordinated contraction...
can be a chronic condition, usually treated with anticoagulation and sometimes with conversionCardioversionCardioversion is a medical procedure by which an abnormally fast heart rate or cardiac arrhythmia is converted to a normal rhythm, using electricity or drugs. Synchronized electrical cardioversion uses a therapeutic dose of electric current to the heart, at a specific moment in the cardiac cycle...
to normal sinus rhythmCardiac pacemakerright|thumb|350px|Image showing the cardiac pacemaker which is the SA nodeThe contraction of heart muscle in all animals with hearts is initiated by chemical impulses. The rate at which these impulses fire controls the heart rate...
. This originates in the Atrium and an electrical impulse is "quivering" (fibrillation). An electrical pulse is given off, but is not the optimal way of sending an electrical pulse.
- Ventricular fibrillationVentricular fibrillationVentricular fibrillation is a condition in which there is uncoordinated contraction of the cardiac muscle of the ventricles in the heart, making them quiver rather than contract properly. Ventricular fibrillation is a medical emergency and most commonly identified arrythmia in cardiac arrest...
is rapidly fatal if not reversed by defibrillationDefibrillationDefibrillation is a common treatment for life-threatening cardiac arrhythmias, ventricular fibrillation and pulseless ventricular tachycardia. Defibrillation consists of delivering a therapeutic dose of electrical energy to the affected heart with a device called a defibrillator...
. No electrical impulse is given off in this form of dysrhythmia.
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. 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 electromyographyElectromyography
Electromyography is a technique for evaluating and recording the electrical activity produced by skeletal muscles. EMG is performed using an instrument called an electromyograph, to produce a record called an electromyogram. An electromyograph detects the electrical potential generated by muscle...
(EMG) and ultrasound. Fibrillations do not occur in healthy individuals. They are a major symptom in acute and severe peripheral nerve disorders, in myopathies in which muscle fibers are split or inflammed, and lower motor neuron lesions.
They contrast with fasciculations that are visible spontaneous contractions involving small groups of muscle fibers. Also, fasciculation does not necessarily denote pathology, as does fibrillation, although it can be seen in lower motor neuron lesions as well.