atrial fibrillation

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fibrillation

 [fi″brĭ-la´shun]
1. a small, local, involuntary, muscular contraction, due to spontaneous activation of single muscle cells or muscle fibers.
2. the quality of being made up of fibrils.
3. the initial degenerative changes in osteoarthritis, marked by softening of the articular cartilage and development of vertical clefts between groups of cartilage cells.
Fibrillation on an electrocardiographic tracing. From Fenstermacher and Hudson, 1995.
atrial fibrillation a reentrant cardiac arrhythmia marked by rapid randomized contractions of the atrial myocardium, causing a totally irregular rapid atrial rate. It is recognizable on an electrocardiogram by the absence of P waves and an irregular ventricular response. It may be controlled by drug therapy or cardioversion.
ventricular fibrillation a cardiac arrhythmia marked by fibrillary contractions of the ventricular muscle due to rapid repetitive excitation of myocardial fibers with ineffectual ventricular contraction; on the surface electrocardiogram it is characterized by lack of identifiable QRS complexes. This is a frequent cause of cardiac arrest. An apparatus called a defibrillator is used to alleviate it by delivering an electric shock to the heart muscle; this depolarizes the myocardium and ends the irregular contractions so that the heart can resume normal, regular contractions.

a·tri·al fi·bril·la·tion

, auricular fibrillation
fibrillation in which the normal rhythmic contractions of the cardiac atria are replaced by rapid irregular twitchings of the muscular wall; the ventricles respond irregularly to the dysrhythmic bombardment from the atria.
Synonym(s): ataxia cordis

atrial fibrillation

n.
Fibrillation in which the normal rhythmical contractions of the cardiac atria are replaced by rapid irregular twitchings of the muscular wall that cause the ventricles to respond irregularly.

atrial fibrillation

Cardiology The most frequent sustained cardiac arrhythmia, which is very common in older individuals and characterized by disorganized electrical conduction in the atria, resulting in ineffective pumping of blood into the ventricle; ± 1 x 106 in US have AF; 80% also have heart disease Etiology HTN, heart failure, valve disease–mitral valve prolapse, rheumatic heart disease, especially when associated with clinically silent mitral stenosis, dilated cardiomyopathy, pericarditis, cardiothoracic surgery, hyperthyroidism, alcohol use or withdrawal, acute illness–eg, pneumonia, decompensated COPD, sepsis, and other conditions, PTE, sympathetic triggers–eg, cocaine, amphetamines, atrial myxoma, tachycardia-bradycardia syndrome, lone AF Risk factors DM, MI, HTN, ↑ age–peak at age 75-79; untreated AF Pts suffer strokes at a rate of 4.5%/yr Sequelae Loss of coordinated electromechanical activity, resulting in blood stasis and atrial thrombosis; AF precipitates heart failure as it results in the loss of the so-called atrial kick, which accounts for 5-30% of cardiac output, and a shorter diastole Clinical Palpitations, dizziness, dyspnea, angina, syncope EKG Narrow QRS complex < 120 msec with no interval between the QRS complexes; absent P waves in leads II, III, aVF, and V1-2 Workup Hx, especially alcohol or drug abuse, thyroid studies, CBC, chemical profile, CXR for pulmonary disease and/or heart failure, EKG, echocardiogram Diagnosis Transesophageal echocardiography identifies Pts with atrial emboli requiring short-term anticoagulation with heparin before cardioversion. See Linkage analysis Management-acute Adenosine, digoxin, magnesium sulfate, CCBs–eg, verapamil, diltiazem Management-long term Cardioversion, anticoagulation Medical conversion of AF Class IA antiarrhythmics–eg, quinidine as well as disopyramide, procainamide, performed as an inpatient; class IC agents–eg, flecanide, propafenone, or class III agents–eg, amiodarone, sotalol are increasingly popular in acute conversion of AF to a sinus rhythm, as is Ibutilide Interventional conversion of AF Failure of medical conversion of AF to a sinus rhythm, accompanied by ventricular rates unresponsive to antiarrhythmics, requires AV node-His bundle ablation with implantation of a rate-adaptive VVI pacemaker, or preferably, atrial or dual chamber pacing, as the incidence of AF is lower than with VVI pacing. See Atrial kick, Atrial flutter.

a·tri·al fi·bril·la·tion

, auricular fibrillation (ā'trē-ăl fib'ri-lā'shŭn, aw-rik'yū-lăr)
Fibrillation in which the normal rhythmic contractions of the cardiac atria are replaced by rapid irregular twitchings of the muscular wall; the ventricles respond irregularly to the dysrhythmic bombardment from the atria.

atrial fibrillation

A heart defect involving the upper chambers in which the rate at which they contract is chaotically irregular both in force and speed. It may be caused by heart muscle damage from RHEUMATIC FEVER or ATHEROSCLEROSIS or by thyroid overactivity. A new focus in the muscle may set up its own rhythm and this may compete with the normal rhythm. Only some of the irregular beats are transmitted down to the lower chambers (ventricles) and the pulse is correspondingly irregular. Atrial fibrillation is common and accounts for one third of all strokes in people over 65 years of age. A rare familial form has been recognized. Treatment by radio frequency ablation using a catheter in a pulmonary vein is usually effective in controlling the disorder. Fibrillation of recent onset can usually be stopped by a single oral dose of flecainide or propafenone.

Atrial fibrillation

A disorder of the heart beat associated with a higher risk of stroke. In this disorder, the upper chambers (atria) of the heart do not completely empty when the heart beats, which can allow blood clots to form.

a·tri·al fi·bril·la·tion

, auricular fibrillation (ā'trē-ăl fib'ri-lā'shŭn, aw-rik'yū-lăr)
Fibrillation in which normal rhythmic contractions of the cardiac atria are replaced by rapid irregular twitchings of the muscular wall.
References in periodicals archive ?
The first modules designed for a FIB were nicknamed mailbox probers because they had to pass through an airlock door similar to a mail slot.
He claimed to have spent two years at Thames University but was later found to have attended a FIBS: Lee and Lorraine hotel and catering course for just four months.