Blood pressure is the force of the blood pushing against the artery walls during contraction and relaxation of the heart. Each time the heart beats, it pumps blood into the arteries. It results in the highest blood pressure as the heart contracts. When the heart relaxes, the blood pressure falls.
Two numbers are recorded when measuring blood pressure. The higher number is called systolic pressure. It refers to the pressure inside the artery when the heart contracts and pumps blood through the body. The lower number is called diastolic pressure. It refers to the pressure inside the artery when the heart is at rest and is filling with blood. Both pressures are recorded as "mm Hg" (millimeters of mercury).
High blood pressure directly increases the risk of heart attack, heart failure, and stroke. With high blood pressure, the arteries may have an increased resistance against the flow of blood. This causes the heart to work harder to circulate the blood.
Blood pressure is categorized as normal, elevated, or stage 1 or stage 2 high blood pressure:
Normal blood pressure is systolic of less than 120 and diastolic of less than 80 (120/80)
Elevated blood pressure is systolic of 120 to 129 and diastolic less than 80
Stage 1 high blood pressure is systolic is 130 to 139 or diastolic between 80 to 89
Stage 2 high blood pressure is when systolic is 140 or higher or the diastolic is 90 or higher
These numbers should be used as a guide only. A single blood pressure measurement that is higher than normal does not necessarily mean there is a problem. Your healthcare provider will want to see multiple blood pressure measurements over several days or weeks before making a diagnosis of high blood pressure and starting treatment. Ask your provider when to contact him or her if your blood pressure readings are not within normal range.