Spontaneous contraction of individual muscle fibers no longer under control of a motor nerve.
The fluttering of a muscle.
Recurrent, involuntary, and abnormal muscular contraction in which a single or a small number of fibers act separately rather than as a coordinated unit, esp. in the heart, as in atrial or ventricular fibrillation. The primary cause is ischemia of the heart muscle. The treatment consists of prompt defibrillation, or drugs (e.g., lidocaine, diltiazem).
Exceedingly rapid contractions or twitching of muscular fibrils, but not of the muscle as a whole.
Rapid, ineffective contractions of the heart, caused by abnormal transmission of electrical impulses from the upper to the lower chambers of the heart. Usually caused by heart disease.
An extremely fast, chaotic heartbeat. Fibrillation reduces or eliminates the ability of the heart chamber to pump blood effectively, depending on what portion of the heart is affected. Fibrillation in the atrium (upper chamber) of the heart is known as atrial fibrillation. Fibrillation in the ventricle (lower chamber) is known as ventricular fibrillation, which is a life- threatening emergency that if not terminated abruptly can lead to death in minutes.
A rapid and chaotic beating of the many individual muscle fibers of the heart, which is consequently unable to maintain effective synchronous contraction. The affected part of the heart then ceases to pump blood.
A term applied to rapid contraction or tremor of muscles, and especially to a form of abnormal action of the heart muscle in which individual bundles of fibres take up independent action. It is believed to be due to a state of excessive excitability in the muscle associated with the stretching which occurs during dilatation of the heart. The main causes are atherosclerosis, chronic rheumatic heart disease and hypertensive heart disease. Fibrillation is either atrial or ventricular, depending on whether the muscle of the atria or of the ventricles is affected. When the atrium is fibrillating there is no significant contraction of the atrial muscle but the cardiac output is maintained by ventricular contraction. In ventricular fibrillation there is no significant contractile force, so that there is no cardiac output and resuscitation by cardiac massage is urgent. The commonest cause is myocardial infarction. Administration of digoxin, timolol or verapamil may restore normal rhythm, and in some patients, cardioversion — a controlled directcurrent electric shock given via a modified defibrillator placed on the chest wall — is effective.
A life-threatening type of arrhythmia in which the heart twitches in an uncoordinated fashion.
Irregular and disorganized contractions of either the upper or lower chambers of the heart, characterized by their rapidity.
Localized, spontaneous, and swift contractions of muscle fibers that can impact both skeletal muscles and the heart.
In skeletal muscle, fibrillation typically arises when the nerve supplying a muscle is damaged, leading to muscle weakness and atrophy. Unlike fasciculation, which is observable as muscular quivering, fibrillation in skeletal muscle is not visible on the skin’s surface. Instead, the contractions can be detected through the use of an electromyogram (EMG).
Fibrillation in the heart muscle occurs due to a disturbance in the propagation of nerve impulses through the wall of one of the heart’s chambers. This disruption can affect either the upper chambers (atria) or the lower chambers (ventricles) of the heart. The condition can be identified through the use of an electrocardiogram (ECG). Fibrillation in the heart muscle is considered serious as it hampers the chambers’ ability to contract effectively, potentially leading to impaired heart function.
Involuntary muscle fiber contractions observed in conditions like progressive muscular atrophy, syringomyelia, and uremia.