Extrasystole


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extrasystole

[¦ek·strə′sis·tə·lē]
(medicine)
Premature beat of the heart.

Extrasystole

 

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.

N. R. PALEEV and I. M. KELMAN

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Detection and evaluation of arrhythmias (supraventricular extrasystoles (SES), supraventricular tachycardia (SVT), ventricular extrasystoles (VES) and ventricular tachycardia (VT)) were performed with 12-lead ECG and 24-hour Holter monitoring records with reference to classic electrocardiographic criteria (12-14).
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was performed preoperatively showing short PR, delta wave, QS in lead II, III and aVF, negative T in I and aVL and frequent ventricular extrasystoles.
6,7) It is also common to find tachycardia, ST and T wave changes, bundle branch block, extrasystoles and prolongation of QT interval.
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AV block and extrasystoles also may occur even within therapeutic level (Kanji & MacLean, 2012).
Perioperative factors, such as atrial extrasystoles, change in autonomic tone, electrolyte shifts, inadequate myocardial protection, b blocker withdrawal, or the response to cardiopulmonary bypass, can trigger AF in these at-risk patients14.
Unsupervised classification of ventricular extrasystoles using bounded clustering algorithms and morphology matching.