SYSTOLIC AND DIASTOLIC PRESSURE
Each time the blood pressure is checked, two figures are recorded: the upper, or systolic pressure, and the lower, or diastolic reading.
The heart in its rhythmic contractions sends out a stream of blood (pulse wave) to the peripheral arteries, where it can be felt as a "pulse." Depending on whether the heart contracts or dilates, the pressure in the arteries will be either higher or lower. Thus the pulse wave, like all waves, crests and then recedes. The highest value, caused by the contraction (systole) of the heart chambers (ventricles) is called systolic pressure, and the lower corresponding to their dilation (diastole) is known as the diastolic pressure. (More about the method of measuring blood pressure will be found on p. 00.) Because the
respective levels of these two pressures, as well as their relationship to each other, furnish valuable clues to the physician both pressures are always taken. Blood pressure, like barometric pressure, is expressed in millimeters of mercury (mm Hg). A measurement of 130/85 mm Hg means a systolic pressure of 130 and a diastolic pressure of 85.
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Cardio & Blood |
