High Blood Pressure: What You Need to Know
High blood pressure, or hypertension, directly increases the risk of coronary heart disease and stroke.
With high blood pressure, the arteries may have an increased resistance against the flow of blood, causing the heart to pump harder to circulate the blood.
Usually, high blood pressure has no signs or symptoms. However, you can know if your blood pressure is high by having it checked regularly by your health care provider.
What is blood pressure?
Blood pressure is the force of the blood pushing against the artery walls. The force is generated with each heartbeat as blood is pumped from the heart into the blood vessels. The size and elasticity of the artery walls also affect blood pressure. Each time the heart beats (contracts and relaxes), pressure is created inside the arteries.
The pressure is greatest when blood is pumped out of the heart into the arteries or systole. When the heart relaxes between beats (blood is not moving out of the heart), the pressure falls in the arteries or diastole.
Two numbers are recorded when measuring blood pressure. The top number, or systolic pressure, refers to the pressure inside the artery when the heart contracts and pumps blood through the body. The bottom number, or diastolic pressure, refers to the pressure inside the artery when the heart is at rest and is filling with blood. Both the systolic and diastolic pressures are recorded as "mm Hg" (millimeters of mercury). This recording represents how high the mercury column in the blood pressure cuff is raised by the pressure of the blood.
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Blood pressure is measured with a blood pressure cuff and stethoscope by a nurse or other healthcare provider. A person cannot take his or her own blood pressure unless an electronic blood pressure monitoring device is used.
The National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health (NIH) has determined two levels of high blood pressure for adults:
The NHLBI defines prehypertension as:
The NHLBI guidelines define normal blood pressure as follows:
These numbers should be used as a guide only. A single elevated blood pressure measurement is not necessarily an indication of a problem. Your physician will want to see multiple blood pressure measurements over several days or weeks before making a diagnosis of hypertension (high blood pressure) and initiating treatment. A person who normally runs a lower-than-usual blood pressure may be considered hypertensive with lower blood pressure measurements than 140/90.
More Information About Hypertension from Johns Hopkins Medicine
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What are the risk factors for high blood pressure?
Nearly one-third of all Americans have high blood pressure, but it is particularly prevalent in:
People who have diabetes, gout, or kidney disease
African Americans (particularly those who live in the southeastern United States)
People in their early to middle adult years; men in this age group have higher blood pressure more often than women in this age group
People in their middle to later adult years; women in this age group have higher blood pressure more often than men in this age group (more women have high blood pressure after menopause than men of the same age)
Middle-aged and elderly people; more than half of all Americans age 60 and older have high blood pressure
People with a family history of high blood pressure
Heavy drinkers of alcohol
Women who are taking oral contraceptives
How does blood pressure increase?
The following conditions are known to contribute to high blood pressure:
How is high blood pressure controlled?
High blood pressure can be controlled by:
Taking prescribed medications exactly as ordered by your health care provider
Choosing foods that are low in sodium
Choosing foods low in calories and fat
Choosing foods high in fiber
Maintaining a healthy weight, or losing weight if overweight
Limiting serving sizes
Increasing physical activity
Reducing or omitting alcoholic beverages
However, other people must take daily medication to control hypertension. People with hypertension should routinely have their blood pressure checked and be under the care of a physician.
Learn More About Hypertension from Johns Hopkins Medicine