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Premature beat of the heart.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



the most common form of arrhythmia. The condition is characterized by irregular heart contractions (extra-systoles) caused by impulses from an additional focus of excitation arising in the myocardium. Since the heart muscle remains unexcitable for some time after every contraction, the next normal impulse usually cannot cause a systole. As a result, a longer than normal contraction, that is, a compensatory pause, occurs. An extrasystole is generally felt as a temporary sinking sensation, or an “interruption in the heart.” Atrial extrasystoles arise in the atria, and ventricular extrasystoles in the ventricles. Extrasystoles may be single or multiple, and they may occur chaotically or with a certain rhythm, for example, after every normal contraction (bigeminal). Sometimes several extrasystoles occur in succession.

Extrasystoles can occur in healthy persons, and, in most cases, occasional infrequent extrasystoles have little clinical significance. Atrial extrasystoles, however, may result from myocardial disease, for example, mitral insufficiency or cardiosclerosis. Frequent atrial extrasystoles in these diseases are an early sign of auricular fibrillation, especially when they occur in rapid succession. Ventricular extrasystoles may result from myocardial disease or neurological, mental, and other disorders. Successive ventricular extrasystoles originating from different places may precede a severe form of arrhythmia called ventricular fibrillation.

Electrocardiography plays an important part in diagnosing ex-trasystoles. Treatment is determined by cause. The administration of antiarrhythmic agents, for example, propranolol and potassium preparations, is sometimes required.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
When the propagation of premature responses (extrasystoles) was explored, the preparation was stimulated regularly at a basic cycle of 500 milliseconds and, after applying eight basic stimuli, a test stimulus was introduced through the same pair of stimulation electrodes at different time intervals.
The other developed a Brugada ECG and frequent ventricular extrasystoles that evolved into ventricular tachycardia and repetitive ventricular arrhythmias (electrical storm) (20).
Premature ventricular contraction (PVC), which is also named ventricular extrasystole, premature ventricular beat, or ventricular ectopia, is early depolarization of the ventricular myocardium [3, 4].
Table-II: Distribution of burnout and anxiety score means in terms of the presence atrial and ventricular extrasystole.
Their studies show that music with frequent changes of rhythm can cause frequent extrasystole. However, the acceleration of musical passages can lead to rhythm disorders in the sense of a extrasystole ventricular tachycardias (Rapiteanu, 2010).
Patients with morbid obesity, anticipated difficult airway (Mallampati score [greater than or equal to] 3), an abnormal ECG (atrial fibrillation or bundle branch block), neuromuscular disease, congestive heart failure, autonomic dysfunction, electrolyte disturbances, congenital long QT syndrome (in the patient or in a family member), or on medications known to prolong the QTc (tricyclic antidepressants, antidysrhythmics, [beta]-adrenergic antagonists, calcium channel blockers), or with ventricular tachycardia, ventricular extrasystole, or a history of known allergy to drugs were excluded from participation.
Arrhythmia which were looked for were atrial premature complex, paroxysmal supraventricular tachycardia, atrial fibrillation and ventricular extrasystole.
(3) Arrhythmias that characterize ARVC include idiopathic ventricular fibrillation, ventricular extrasystoles, supraventricular tachycardia, (4) and ventricular tachycardia of right ventricular origin (with a left bundle branch pattern).
Some of the subjects were taking long-acting nitrates or 3-blockers for coronary disease or verapamil for extrasystoles. These drugs were withdrawn a week before the test.
A 24 hour Holter monitoring revealed sinus rhythm with frequent atrial extrasystoles, episodes of atrial fibrillation (AF) and paroxysmal narrow QRS tachycardia alternating with WQT (170-180 bpm) (Figure 2).