The time period when the heart is in a state of relaxation and dilatation (expansion). The final letter in "diastole" is pronounced as a long "e" as in "lee." The adjective for diastole is diastolic. The diastolic pressure is specifically the minimum arterial pressure during relaxation and dilatation of the ventricles of the heart. Diastole is the time when the ventricles fill with blood. In a blood pressure reading, the diastolic pressure is typically the second number recorded. For example, with a blood pressure of 120/80 ("120 over 80"), the diastolic pressure is 80. By "80" is meant 80 mm Hg (millimeters of mercury). A diastolic murmur is a heart murmur heard during diastole, the time the heart relaxes. "Diastole" came without change from the Greek diastole meaning "a drawing apart." The term has been in use since the 16th century to denote the period of relaxation of the heart muscle.
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Normal postsystolic dilation of the heart cavities, during which they fill with blood; d. of the atria precedes that of the ventricles; d. of either chamber alternates rhythmically with systole or contraction of that chamber. [G. d., dilation]
- electrical d. period from end of T wave to beginning of next Q wave.
- gastric d. a phase of relaxation of stomach peristalsis seen fluoroscopically or with the gastroscope.
- late d. SYN: presystole.

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di·as·to·le dī-'as-tə-(.)lē n
1) the passive rhythmical expansion or dilation of the cavities of the heart during which they fill with blood compare SYSTOLE
2) the rhythmical expansion of a pulsating vacuole (as of an ameba)
di·a·stol·ic .dī-ə-'stäl-ik adj

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the period between two contractions of the heart, when the muscle of the heart relaxes and allows the chambers to fill with blood. The term usually refers to ventricular diastole, which lasts about 0.5 seconds in a normal heart rate of about 70/minute. During exertion this period shortens, so allowing the heart rate to increase. See also blood pressure, systole.
diastolic adj.

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di·as·to·le (di-asґto-le) [Gr. diastolē a drawing asunder; expansion] the dilatation, or period of dilatation, of the heart, especially of the ventricles; it coincides with the interval between the second and the first heart sounds. Cf. systole and see illustration at cardiac cycle, under cycle. diastolic adj

Medical dictionary. 2011.