What Are Hypertension and Prehypertension?
Blood pressure is the force of blood against the walls of
arteries. Blood pressure rises and falls during the day. When
blood pressure stays elevated over time, it is called high
The medical term for high blood pressure is hypertension.
High blood pressure is dangerous because it makes the heart work
too hard and contributes to atherosclerosis (hardening of the
arteries). It increases the risk of heart disease and stroke,
which are the first- and third-leading causes of death among
Americans. High blood pressure also can result in other
conditions, such as congestive heart failure, kidney disease,
A blood pressure level of 140/90 mmHg or higher is considered
high. About two-thirds of people over age 65 have high blood
pressure. If your blood pressure is between 120/80 mmHg and
139/89 mmHg, then you have prehypertension. This means
that you don't have high blood pressure now but are likely to
develop it in the future. You can take steps to prevent high
blood pressure by adopting a healthy lifestyle.
Those who do not have high blood pressure at age 55 face a 90
percent chance of developing it during their lifetimes. So high
blood pressure is a condition that most people have at some
point in their lives.
Both numbers in a blood pressure test are important, but for
people who are 50 or older, systolic pressure gives the most
accurate diagnosis of high blood pressure. Systolic pressure is
the top number in a blood pressure reading. It is high if it is
140 mmHg or above.
What is systolic blood pressure?
Systolic pressure is the force of blood in the arteries as
the heart beats. It is shown as the top number in a blood
pressure reading. High blood pressure is 140 and higher for
systolic pressure. Diastolic pressure does not need to be high
for you to have high blood pressure. When that happens, the
condition is called "isolated systolic hypertension," or ISH.
Is isolated systolic high blood pressure common?
Yes. It is the most common form of high blood pressure
for older Americans. For most Americans, systolic blood
pressure increases with age, while diastolic increases until
about age 55 and then declines. About 65 percent of
hypertensives over age 60 have ISH. You may have ISH and
feel fine. As with other types of high blood pressure, ISH
often causes no symptoms. To find out if you have ISH — or
any type of high blood pressure — see your doctor and have a
blood pressure test. The test is quick and painless.
Is isolated systolic high blood pressure dangerous?
Any form of high blood pressure is dangerous if not
properly treated. Both numbers in a blood pressure test are
important, but, for some, the systolic is especially
meaningful. That's because, for those persons middle aged
and older, systolic pressure gives a better diagnosis of
high blood pressure.
If left uncontrolled, high systolic pressure can lead to
stroke, heart attack, congestive heart failure, kidney
damage, blindness, or other conditions. While it cannot be
cured once it has developed, ISH can be controlled.
Clinical studies have proven that treating a high
systolic pressure saves lives, greatly reduces illness, and
improves the quality of life. Yet, most Americans do not
have their high systolic pressure under control.
Does it require special treatment?
Treatment options for ISH are the same as for other types
of high blood pressure, in which both systolic and diastolic
pressures are high. ISH is treated with lifestyle changes
and/or medications. The key for any high blood pressure
treatment is to bring the condition under proper control.
Blood pressure should be controlled to less than 140/90
mmHg. If yours is not, then ask your doctor why. You may
just need a lifestyle or drug change, such as reducing salt
in your diet or adding a second medication.
What is diastolic blood pressure?
Diastolic pressure is the force of blood in the arteries as
the heart relaxes between beats. It's shown as the bottom number
in a blood pressure reading.
The diastolic blood pressure has been and remains, especially
for younger people, an important hypertension number. The higher
the diastolic blood pressure the greater the risk for heart
attacks, strokes and kidney failure. As people become older, the
diastolic pressure will begin to decrease and the systolic blood
pressure begins to rise and becomes more important. A rise in
systolic blood pressure will also increase the chance for heart
attacks, strokes, and kidney failure. Your physician will use
both the systolic and the diastolic blood pressure to determine
your blood pressure category and appropriate prevention and