What Those Blood Pressure Numbers Mean

A quick, painless test measures blood pressure: A rubber cuff is wrapped around your arm and inflated; that compresses an artery in your arm and momentarily stops your blood flow. A technician uses a stethoscope to measure your blood pressure when the pressure in the cuff is slowly released.

Blood pressure readings are a double measurement of the force of the blood against arterial walls. The two measurements indicate how much pressure builds up in the arteries as the heart beats and between beats. The first, higher number is the systolic pressure, which indicates the heart's pumping force. The second, lower number is the diastolic pressure, which indicates the flexibility and clogging in the arteries.

The higher the blood pressure, the more resistance there is to blood flow. A blood pressure level with the systolic less than 120 and the diastolic less than 80 is considered optimal. If the systolic is 120 to 139 or the diastolic is 80 to 89, this is called prehypertension regardless if one of them is normal. If the systolic is 140 or higher or the diastolic is 90 or higher, this is called hypertension regardless whether one of the readings is normal or in the prehypertensive range.

To make a diagnosis of prehypertension or hypertension, your doctor will measure your blood pressure over several visits. If it is elevated two out of three visits, the diagnosis can be made. Hypertension is a sign that the heart is working too hard to pump blood through the circulatory system because of narrow and/or inflexible arteries.