Blood pressure values are expressed as systolic pressure over diastolic pressure. Systolic pressure is the amount of pressure in your arteries when the heart is contracting. Diastolic pressure is taken when the heart is relaxing and filling with blood. Normal blood pressure ranges from 90/60 to 140/80. If either number is consistently higher than these ranges, you have high blood pressure. However, blood pressure varies with exercise, emotions, and stress.
The diastolic pressure, the systolic pressure, or both may be elevated. A high diastolic pressure can cause damage to the kidneys and to blood vessels throughout the body. A high systolic pressure increases the risk of coronary artery disease and stroke.
More than 58 million people in the United States have high blood pressure. It is the most common cardiovascular disease. Slightly more than 54% of Americans older than 60 have high blood pressure and this number rises to 64% for Americans over 70 years of age.