Both systolic and diastolic readings are important, but diastolic pressure has traditionally been emphasized because it is less subject to fluctuations. However, recent studies have revealed that systolic pressure may be as significant a heart attack predictor as diastolic pressure.
| Category | Systolic (mmHg) | Diastolic (mmHg) |
|---|---|---|
| Optimal | <120 | <80 |
| Normal | <130 | <85 |
| High Normal | 130 - 139 | 85 - 89 |
| Hypertension | ||
| Stage 1 | 140 - 159 | 90 - 99 |
| Stage 2 | 160 - 179 | 100 - 109 |
| Stage 3 | > 180 | > 110 |
Normal blood pressure is thus usually said to be 120/80 (systolic/diastolic) or less, measured in millimeters of mercury (abbreviated as mm Hg). What do blood pressure numbers indicate? The higher (systolic) number represents the pressure while the heart is beating. The lower (diastolic) number represents the pressure when the heart is resting between beats.
The systolic pressure is always stated first and the diastolic pressure second. For example: 122/76 (122 over 76); systolic = 122, diastolic = 76. Blood pressure of less than 140 over 90 is considered a normal reading for adults. A systolic pressure of 130 to 139 or a diastolic pressure of 85 to 89 needs to be watched carefully. A blood pressure reading equal to or greater than 140 (systolic) over 90 (diastolic) is considered elevated (high).
In some people, the system that regulates blood pressure goes awry: arteries
throughout the body stay constricted, driving up the pressure in the larger
blood vessels. Sustained high blood pressure - above 140/90 mm Hg, according
to most experts - is called hypertension. About 90 percent of all people with
high blood pressure have "essential" hypertension - meaning that it has no
identifiable cause. In the remaining 10 percent of cases, the elevated blood
pressure is due to kidney disease, diabetes, or another disorder.
