extrasystole

(ĕks″tră-sĭs′tō-lē )

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[″ + Gr. systole, contraction]
Premature contraction of the heart. It may occur in the presence or absence of organic heart disease. It may be of reflex origin or may be triggered by stimulants, e.g., caffeine, cocaine, or theophylline, hypoxia, psychological stress, electrolyte abnormalities, thyroid disorders, or myocardial infarction.

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