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Premature beat of the heart.



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.


References in periodicals archive ?
This study aimed to investigate the relationship between levels of anxiety and burnout and the prevalence of atrial extrasystoles (AESs) and ventricular extrasystoles (VESs) among critical care nurses.
Holter ECG device Syneflash Card MinHR/24h revealed findings composed of an hour intervals of the heart-rate, pause, missed beats, supraventricular extrasystoles (isolated and couplet), ventricular extrasystoles (isolated and couplet), total extrasystoles and ST segment deviations each.
9-11,13 Altered load changes myocardial segment length that, acutely, can result in decreased resting potential and the occurrence of after-depolarizations that cause extrasystoles in the region of greatest stretch.
The susceptibility to ventricular arrhythmias can be explained by the imbalance of currents creating a vulnerable window during which time an extrasystole can trigger a phase 2 re-entry arrhythmia (9).
Frequent ventricular extrasystoles during exercise indicate underlying cardiac disease [13].
Twelve patients had hemodynamic instability that required vasoconstrictors and 6 had arrhythmias, mainly supraventricular and ventricular extrasystoles.
2002) Increasing plasma potassium with amiloride shortens the QT interval and reduces ventricular extrasystoles but does not change endothelial function or heart rate variability in chronic heart failure.
TABLE 2 Causes of an irregular pulse Sinus arrhythmia Atrial extrasystoles Ventricular extrasystoles Atrial fibrillation Atrial tachycardia with variable response Second-degree heart block Source: Munro and Campbell, eds, MacLeod's Clinical Examination, 2000.
In levosimendan treated patients extrasystoles were reported in 1.
The investigators found 55% were in sinus rhythm and 43% had isolated extrasystoles.