atrial fibrillation

fibrillation /fi·bril·la·tion/ (fĭ″brĭ-la´shun)

1. the quality of being made up of fibrils.

2. a small, local, involuntary, muscular contraction, due to spontaneous activation of single muscle cells or muscle fibers whose nerve supply has been damaged or cut off.

3. the initial degenerative changes in osteoarthritis, marked by softening of the articular cartilage and development of vertical clefts between groups of cartilage cells.

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atrial fibrillation  atrial arrhythmia marked by rapid randomized contractions of small areas of the atrial myocardium, causing a totally irregular, and often rapid, ventricular rate.

ventricular fibrillation  cardiac arrhythmia marked by fibrillary contractions of the ventricular muscle due to rapid repetitive excitation of myocardial fibers without coordinated ventricular contraction and by absence of atrial activity.

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atrial fibrillation

n. Abbr. AF

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. Also called a-fib, auricular fibrillation.

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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.

Mentioned in: Arterial Embolism, Cardioversion, Carotid Sinus Massage, Stroke, Tricuspid Valve Insufficiency, Ventricular Fibrillation

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atrial fibrillation (AF)

[ā′trē·əl]

a cardiac arrhythmia characterized by disorganized electrical activity in the atria accompanied by an irregular ventricular response that is usually rapid. The atria quiver instead of pumping in an organized fashion, resulting in compromised ventricular filling and reduced stroke volume. Stasis of left atrial flow increases the risk of stroke as a result of clot formation. AF is associated with hypertension, diabetes, age, rheumatic heart disease (left atrial dilation), mitral stenosis, acute myocardial infarction, and heart surgery, or it may be idiopathic (lone AF). Treatment goals are to control the ventricular rate by creating atrioventricular block, to prevent stroke through the use of anticoagulants, and to convert to sinus rhythm. Treatment categories include paroxysmal, persistent, and chronic. AF is called controlled if ventricular response is less than 100. If ventricular response is 100 or more, it is called uncontrolled atrial fibrillation.

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atrial fibrillation (āˑ·trē·l fi·bri·lāˑ·shn),

n quick uncoordinated twitching movements of the muscles of the atria of the heart; may result in a lack of regular pulse and lowered circulation.

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atrial fibrillation,

n a heart condition characterized by rapid random contractions of the atria at the rate of 130 to 150 ventricular beats per minute.

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fibrillation

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.

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atrial fibrillation

a cardiac arrhythmia marked by rapid randomized contractions of the atrial myocardium, causing a totally irregular, often rapid, ventricular rate. There is no synchronous atrial contraction and the ventricles beat irregularly. The heartbeat is irregular, the pulse is irregular in rhythm and amplitude. Common in the horse; an affected animal can still race but the performance is poor. Occurs in dogs in association with cardiac disease, particularly idiopathic congestive cardiomyopathy, and electrolyte disturbances.

ventricular fibrillation

a cardiac arrhythmia marked by fibrillatory contractions of the ventricular muscle due to rapid repetitive excitation of myocardial fibers without coordinated ventricular contraction. Ventricular fibrillation is a frequent cause of cardiac arrest. An apparatus called a defibrillator sometimes is used to alleviate fibrillation. The defibrillator delivers an electric shock to the heart muscle, depolarizing the muscle and ending the irregular contractions. The heart is then able to resume normal, regular contractions.

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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 V_1-2 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.