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Contraction of the heart, especially of the ventricles, by which the blood is driven through the aorta and pulmonary artery to traverse the systemic and pulmonary circulations, respectively; its occurrence is indicated physically by the first sound of the heart heard on auscultation, by the palpable apex beat, and by the arterial pulse. [G. s., a contracting]
- aborted s. a loss of the systolic beat in the radial pulse through weakness of the ventricular contraction.
- electrical s. the duration of the QRST complex ( i.e., from the earliest Q wave to the end of the latest T wave on the ECG).
- electromechanical s. the period from the beginning of the QRS complex to the first (aortic) vibration of the second heart sound. SYN: QS2 interval.
- extra- s. extrasystole.
- late s. SYN: prediastole.
- premature s. SYN: extrasystole.
- ventricular s. contraction of the ventricles.
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sys·to·le 'sis-tə-(.)lē n the contraction of the heart by which the blood is forced onward and the circulation kept up compare DIASTOLE (1)
sys·tol·ic sis-'täl-ik adj
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n.
the period of the cardiac cycle during which the heart contracts. The term usually refers to ventricular systole, which lasts about 0.3 seconds. Atrial systole lasts about 0.1 seconds.
• systolic adj.
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sys·to·le (sisґto-le) [Gr. systolē a drawing together, contraction] the contraction, or period of contraction, of the heart, especially that of the ventricles; sometimes divided into components, as preejection and ejection periods, or isovolumic and ejection.Medical dictionary. 2011.