An in-depth report on the causes, diagnosis, treatment, and prevention of high blood pressure.
High blood pressure, also called hypertension, is elevated pressure of the blood in the arteries. Hypertension results from two major factors, which can be present independently or together:
Although the body can tolerate increased blood pressure for months and even years, eventually the heart may enlarge (a condition called hypertrophy), which is a major factor in heart failure.
Such pressure can also injure blood vessels in the heart, kidneys, the brain, and the eyes.
Two numbers are used to describe blood pressure: the systolic pressure (the higher and first number) and the diastolic pressure (the lower and second number). Health dangers from blood pressure may vary among different age groups and depending on whether systolic or diastolic pressure (or both) is elevated. A third measurement, pulse pressure, may also be important as an indicator of severity.
Systolic Blood Pressure. The systolic pressure (the first and higher number) is the force that blood exerts on the artery walls as the heart contracts to pump out the blood. High systolic pressure is now known to be a greater risk factor than diastolic pressure for brain, heart, kidney, and circulatory complications and for death, particularly in middle-aged and elderly adults. The wider the spread between the systolic and diastolic measurements, the greater the danger.
Diastolic Blood Pressure. The diastolic pressure (the second and lower number) is the measurement of force as the heart relaxes to allow the blood to flow into the heart. High diastolic pressure is a strong predictor of heart attack and stroke in young adults.
Pulse Pressure. Pulse pressure is the difference between the systolic and the diastolic readings. It indicates stiffness and inflammation in the blood-vessel walls. The greater the difference between systolic and diastolic numbers, the stiffer and more injured the vessels are thought to be.
Some studies suggest that in people over 45 years old, every 10 mm Hg increase in pulse pressure increases the risk for stroke rises by 11%, cardiovascular disease by 10%, and overall mortality by 16%. (In younger adults the risks are even higher.)
There are a number of ways to categorize or describe hypertension.
Other doctors categorize hypertension based on what portion of the blood pressure reading is abnormal:
Blood pressure is measured in millimeters of mercury (mm Hg). According to current adult guidelines, blood pressure is categorized as normal, prehypertensive, and hypertensive (which is further divided into Stage 1 and 2, according to severity).
Current guidelines for children are based on percentile ranges for a childâ ' s body size. Hypertension is defined as average systolic and diastolic readings that are greater than the 95th percentile for gender, age, and height on at least three occasions.
Pre-hypertension in children is diagnosed when average systolic or diastolic blood pressure levels are at least in the 90th percentile but less than the 95th percentile. For adolescents, as with adults, blood pressure readings greater than 120/80 are considered prehypertensive. Increasing rates of childhood obesity have led to increasing rates of hypertension and pre-hypertension among children and adolescents. Although more children are having high blood pressure, recent studies indicate that pediatric hypertension is frequently underdiagnosed.
Blood Pressure Ranges
Blood Pressure Category
Ranges for Most Adults (systolic/diastolic)
Normal Blood Pressure (systolic/diastolic)
Systolic below 120 mm Hg
Diastolic below 80 mm Hg
Systolic 120 - 139 mm Hg
Diastolic 80 - 89 mm Hg
(NOTE: 139/89 or below should be the minimum goal for everyone. People with heart disease, peripheral artery disease, diabetes or chronic kidney disease should strive for 130/80 or less.)
Mild Hypertension (Stage 1)
Systolic 140 - 159 mm Hg
Diastolic 90 - 99 mm Hg
Moderate-to-Severe Hypertension (Stage 2)
Systolic over 160 mm Hg or
Diastolic over 100 mm Hg
Note: If one of the measurements is in a higher category than the other, the higher measurement is usually used to determine the stage. For example, if systolic pressure is 165 (Stage 2) and diastolic is 92 (Stage 1), the patient would still be diagnosed with Stage 2 hypertension. A high systolic pressure compared to a normal or low diastolic pressure should be a major focus of concern in most adults.
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