HIGH BLOOD PRESSURE

C H A P T E R 1 2
HIGH BLOOD
PRESSURE
MARVIN MOSER, M.D.
since 1973–74. At that time, the National High Blood
INTRODUCTION Pressure Education Program directed at both phy-
sicians and the general public raised consciousness
about the dangers of untreated high blood pressure
High blood pressure, or hypertension as the disease
and the importance of early effective treatment. We
is known medically, is our most common chronic ill-
are now reaping the benefits of this and other major
ness. Estimates of exactly how many Americans have
programs.
high blood pressure vary—the American Heart As-
Even so, it’s still too early to declare victory over
sociation and the National Heart, Lung, and Blood
high blood pressure. Despite massive public educa-
Institute put the figure at about 55–60 million, but
tion programs, misconceptions about the disease
some of the individuals included in this estimate may
abound. Many people still harbor misconceptions
only have had transient elevation of pressure; a more
about what constitutes an elevated blood pressure
accurate estimate is probably 35–40 million. In either
(see box, “Common Facts and Myths”), and there
calculation, the number of people affected and the
probably still are many people whose high blood
amount of the nation’s health budget that goes
pressure has not been diagnosed—especially in mi-
toward treating high blood pressure or its compli-
nority populations. There also are several millions of
cations are huge.
others whose hypertension has been diagnosed but
Because high blood pressure is the leading cause
who are not being adequately treated to normal blood
of strokes and a major risk factor for heart attacks,
pressure levels.
one of the most important aspects of preventive car-
diology should be to identify as many people who
have the disease as possible and to take steps to lower
the blood pressure before it causes damage to the
WHAT IS HIGH BLOOD PRESSURE
blood vessels, heart, kidneys, eyes, and other organs.
Fortunately, the last 30 to 35 years have seen re-
OR HYPERTENSION
markable advances in the treatment of high blood
pressure, with major payoffs. The death toll from
strokes is down by more than 54 percent and heart
To understand why lowering high blood pressure is
attack mortality has dropped by more than 45 percent
so important in preventing heart and blood vessel
149

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MAJOR CARDIOVASCULAR DISORDERS
diseases, it is important to know something about the
basic physiology involved. As noted in Chapter 1, the
blood circulates through some 60,000 miles of blood
vessels. (See color atlas, #4.) With each heartbeat, 2
or 3 ounces of freshly oxygenated blood are forced
out of the heart’s main pumping chamber, the left
ventricle, into the aorta, the body's largest artery.
The circulatory system can be likened to a tree.
The aorta is comparable to the main tree trunk. It
branches into smaller arteries (like the thick branches
that come off the main trunk), which in turn divide
into even smaller vessels (like smaller branches and
twigs) called arterioles, which carry blood to the cap-
illaries (like the leaves). Capillaries are the micro-
scopic vessels that supply blood, with its load of
oxygen and other nutrients, to each cell in the body.
After the oxygen is used up, the blood returns to the
heart via a branching system of veins.
A certain amount of force is needed to keep blood
moving through this intricate system of blood vessels.
The amount of force that is exerted on the artery walls
as blood flows through them is what we refer to as
blood pressure. The “head” of pressure comes from
the heart, but it is the smallest arteries, the arterioles,
that actually determine how much pressure is reg-
istered in the blood vessels. To raise blood pressure,
the arterioles narrow or constrict to lower it, they
open up or dilate.
Exactly how much pressure is needed varies ac-
cording to the body’s activities. For example, the
heart does not need to beat as fast or as hard to keep
blood circulating when you are resting as it does
when you are exercising. During exercise, however,
more blood is needed to carry oxygen to the muscles,
so blood pressure rises to meet increased demand.
The heart pumps faster and pushes out more blood
with each beat. In other situations, such as when
someone stands up suddenly after lying down, the
body must make an almost instantaneous adjustment
in blood pressure in order to ensure a steady supply
of blood to the brain. Blood vessels in the abdomen
and legs constrict and the heart speeds up. Some-
times there may be a slight delay in this adjustment,
and as a result, you may feel dizzy for a few seconds.
This is more common in older people whose blood
vessel reflexes might be impaired. A longer delay can
bring on a fainting spell, which is the body's way of
increasing the flow of blood to the brain (when some-
one lies down, blood flow to the brain increases).
Similarly, some people feel light-headed, or even
faint, after standing for long periods, during which
time blood may collect or “pool” in the legs, thereby
reducing the amount that is available to carry oxygen

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HIGH BLOOD PRESSURE
to the brain. Good examples of this bodily response
pressure, is the amount of force exerted when the
are the numerous instances of healthy soldiers who
heart is resting momentarily between beats.
fainted after standing at attention for long periods of
Blood pressure is usually measured with a device
time in hot weather. Other reflexes maybe triggered
called a sphygmomanometer (pronounced sfig-moe-
and result in a sudden loss of blood to the brain and
man-om-e-ter), which consists of an inflatable rubber
an episode of light-headedness or fainting. These ep-
cuff, an air pump, and a column of mercury or a dial
isodes are not serious but can be frightening. An ex-
or digital readout reflecting pressure in an air col-
ample of this response is fainting after only a small
umn. Readings are expressed in millimeters of mer-
amount of blood is drawn for a blood test. A nerve
cury or mm Hg. (See Figure 12.1.) The cuff is wrapped
reflex slows the heart and causes blood vessels to
around the upper arm, and the inflatable cuff is tight-
dilate or open up, Less blood gets to the brain and
ened until blood flow through the large artery in the
fainting occurs. As we all know, if the affected indi-
arm is halted. As air is pumped into the cuff, it pushes
vidual rests quietly for just a few minutes, all is well.
up a column of mercury or air, in the case of the
Blood pressure is regulated by an intricate system
simpler machines.
of hormonal controls and nerve sensors, and it may
The person measuring the blood pressure places
vary considerably during the course of a day. Typi-
a stethoscope over the artery just below the cuff and
cally, blood pressure is low when you are resting or
listens for a cessation of the sound of blood coursing
asleep, and higher when you are moving about or
through the artery. He or she then begins to release
under stress. For example, when you are frightened
air from the cuff, allowing blood to flow through the
or angry, the adrenal glands pump out epinephrine
artery again. As air is released, the column of mer-
and norepinephrine, stress hormones that are com-
cury or air begins to fall, and the person listens for
monly referred to as adrenaline. These hormones,
the first thumping sound that signals a return of blood
which are responsible for the body’s fight-or-flight
flow into the vessel over which the stethoscope has
response, signal the heart to beat faster and harder,
been placed. The height of the column of mercury or
resulting in increased blood pressure and flow to the
the air pressure on the dial at this sound indicates
muscles. It is apparent that pressures are typically
the systolic (or higher) pressure. More air is released
lowest between 1:00 and 4:00 or 5:00 A.M., rise rapidly
during “arousal” from sleep between 6:00 and 8:00
Figure 12.1
Blood pressure is measured using a device called a
A. M., remain at approximately the same levels during
sphygmomanometer, which consists of an inflatable cuff that
the afternoon and evening, and decrease from about
goes around the arm. The blood pressure reading is obtained from
the height of a column of mercury which is connected to the
11:00 to 12:00 at night.
cuff.
WHAT CONSTITUTES HIGH BLOOD
PRESSURE?
Blood does not flow in a steady stream; instead, it
moves through the circulatory system in spurts that
correlate with the heart’s beats. The heart beats about
60 to 70 times a minute at rest and may speed up to
120 to 140 or higher during vigorous exercise, It is
not contracting or squeezing all the time, however;
after each contraction, the heart muscle rests and gets
ready for the next beat. Blood pressure rises and falls
with each beat. Thus, blood pressure is expressed in
two numbers, such as 120 over 80, or 120/80. The
higher number, which is called systolic pressure, rep-
resents the maximum force that is exerted on the
walls of the blood vessels during a heartbeat. The
lower number, which is referred to as the diastolic

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MAJOR CARD1OVASCULAR DISORDERS
are consistently above 140/90 warrant a diagnosis of
Monitoring Your Own
hypertension, and the higher the readings, the more
Blood Pressure.
serious the disease. (See Table 12.1.) A reading of
about 140/90 does not necessarily indicate that the
Most people with hypertension do not need to
condition requires immediate therapy, but it does
measure their blood pressures at home. Some,
suggest follow up and some treatment.
however, find home monitoring reassuring. It is
important to remember that an occasional high
reading does not necessariIy mean that your
STEPS IN ESTABLISHING
blood pressure is “out of control. ”
in some instances, home monitoring may provide
A DIAGNOSIS
useful information for your doctor, especiaIly if
you are starting a new drug regimen or
experiencing symptoms, such as dizziness. If
OF HIGH BLOOD PRESSURE
you do monitor your blood pressure at home,
you should take your machine with you
periodically when you visit your doctor so that
A diagnosis of high blood pressure should not be
he or she can check whether it is correctly
based on a single reading, except when it is extremely
caI i brated.
high—for example, above 170–180/105–110. Other-
Before starting home monitoring, ask your doctor or
nurse to show you the proper way to use your
machine. Most people find the electronic
Table 12.1
machines that do not have a separate
stethoscope easier to use than the
Recommendations for Management of Various
nonautomated ones. But they may not be quite
Blood Pressure Levels
as accurate. Whichever model you use, follow
the instructions from the manufacturer and your
Range
Recommended
doctor. Special points to remember include:
(mm Hg)
Diagnosis
activity
Diastolic
q Avoid caffeine (coffee, tea, colas, etc.) for at
‘least 30 minutes before measuring your blood
below 85
Normal blood
Recheck within
pressure. The same goes for cigarettes or
pressure
2 years.
nicotine gum. Both caffeine and nicotine raise
blood pressure and can give a falsely high
85-89
High normal blood
Recheck within
reading.
pressure
1 year.
q If you are experiencing dizziness or feelings of
faintness, try taking your blood pressure
90-104
Mild hypertension
Confirm within
immediately after standing up to see if it differs
2 months.
from pressure taken while sitting.
105-114
Moderate
Therapy should
hypertension
be undertaken.
above 115
Severe hypertension
Begin therapy
from the cuff, and pressure continues to fall. The
with medication
height of the mercury or the level of air pressure
Isolated systolic hypertension, when diastolic blood
when the thumping sound of blood ceases, indicating
pressure is below 90 (mostly seen in older individuals)
the pause between heartbeats, is the diastolic
pressure.
below 140
Normal blood
Recheck within
People with high blood pressure can learn to mon-
pressure
2 years.
itor their own pressure (See box, “Monitoring Your
140-159
Borderline isolated
Confirm within
Own Blood Pressure”), although for most it is not
systolic hypertension
2 months.
necessary.
160-199
Isolated systolic
Confirm within
As noted earlier, blood pressure varies consider-
hypertension
2 months.
ably during the course of an average day. It also var-
Therapy should
ies according to age—a baby’s blood pressure may
be instituted if
normally be 70/50, whereas the average blood pres-
pressure remain
sure in an adult is about 120/80. Until recent years,
elevated.
there was no clear agreement among physicians as
to what constituted high blood pressure, but now it
above 200
Isolated systolic
Begin therapy
hypertension
with medication
is generally agreed that blood pressure readings that

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HIGH BLOOD PRESSURE
wise several measurements taken over a period of
usually high—for example, above 140 systolic and 90
time are generally needed to confirm a diagnosis. This
diastolic. In older people, however, there is a form of
is why single readings obtained at health fairs or
hypertension called isolated systolic hypertension.
other blood pressure screening events are often mis-
The systolic, or upper, reading may be high, for ex-
leading. In addition, the electronic machines used for
ample, 150–180, but the diastolic, or lower, reading
self-measurement at airports or in pharmacies are
is below 90. (See Table 12.1.) This type of hyperten-
often poorly calibrated or improperly used and may
sion also results in an increased risk of stroke, heart
give false readings (usually on the high side), Al-
attack, or heart failure.
though hypertension screening has its place, people
In addition to measuring blood pressure, the doc-
should understand that readings obtained are only
tor will also look for signs of organ damage, if the
an indication to follow up more carefully, and do not
readings are high. Specifically, the examination will
justify a definite diagnosis of high blood pressure or
include:
hypertension. Unfortunately, many people are unduly
frightened, on the basis of just one blood pressure
• Inspection of the eyes. The eyes are the only
recording, into thinking they have hypertension.
place in the body where blood vessels can be
The circumstances under which blood pressure is
looked at directly. By shining a bright light into
measured must also be taken into consideration. For
the eye and inspecting its interior with an
example, a blood pressure reading taken when a per-
ophthalmoscope (a special magnifing device),
son is under severe stress maybe misleadingly high.
the doctor can inspect the blood vessels for
Similarly, a high reading may be obtained if blood
thickening or narrowing, changes that are
pressure is measured soon after a person has had a
characteristic of high blood pressure. He or she
couple of cups of coffee or smoked a few cigarettes.
will also look for tiny hemorrhages inside the
Thus, if possible, a person should avoid smoking
eye, another possible sign of damage from high
and/or drinking coffee, cola, or other sources of caf-
blood pressure.
feine for about one to two hours before having blood
• Examination of the heart. This includes a careful
pressure measured.
examination using a stethoscope to listen for
In a physician’s office or clinic, blood pressure is
any unusual sounds or beats and palpation of
usually measured after the doctor has asked ques-
tions about the patient’s health history. This also
gives the patient a few minutes to relax, although
some people remain anxious. (See box, “White-Coat
Hypertension.”) Two readings may be taken—the
first with the person seated, and the second while
standing. The reading while standing may be espe-
cially useful in older persons whose pressures may
fall when they stand up. And it can help to guide
treatment decisions, since some blood-pressure-low-
ering drugs may cause a greater decrease in standing
than in sitting blood pressures. Blood pressure may
be measured several times during the visit, especially
if the first reading was on the high side, The results
of all the readings are then usually averaged.
In an adult, blood pressure recordings need only
be repeated every one to two years if pressures are
below 140/90. If the average falls in the mild to mod-
erate range of high blood pressure, about 140/90 to
160/100, an appointment for additional measure-
ments will be made to confirm the diagnosis. How-
ever, very high diastolic blood pressure readings
(more than 110 to 115 mm Hg) during the course of
an office visit justify starting treatment. If an elevated
blood pressure is present in individuals below 60
years of age, both the systolic and diastolic levels are
153

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MAJOR CARDIOVASCULAR DISORDERS
the heart impulse to judge heart size. An elec- •
Examination of the kidneys. By pressing on the
trocardiogram will measure the hearts electri-
abdomen, a doctor may be able to tell if the
cal activity and help to determine if the heart is
kidneys are enlarged, which may indicate a spe-
enlarged.
cific type of hypertension. This type of high
blood pressure is rare.
q A check of blood flow in the arteries. Pulses will
be felt at various parts of the body, including •
A check for an enlarged thyroid. A swelling in
the wrists, neck, and ankles. The doctor may
the neck (a goiter) may be a sign of an over-
use a stethoscope to listen to blood flowing
active or underactive thyroid, conditions that
through the carotid artery, the large blood ves-
can elevate blood pressure.
sel in the neck that carries blood to the brain.
A humming noise (called a bruit) may indicate
In addition to the physical examination, the doctor
a narrowing of this artery. Similarly, the doctor
will likely order a urinalysis to check for possible kid-
will probably listen for bruits in the abdominal
ney damage or a bladder infection, and blood tests,
arteries that carry blood to the kidneys. If a
especially to measure blood sugar (glucose) and cho-
specific kind of bruit or murmur is found it may
lesterol levels and to estimate kidney function. Any
indicate that the high blood pressure has re-
abnormality in either the physical examination or lab
suited from a narrowing of one of the arteries
studies that indicates possible damage to the heart,
of the kidneys.
kidneys, eyes, or blood vessels (the major “target”
Tests, That Are Often Overused
In the majority of patients, hypertension and possible
and records blood pressure every 15 or 30 minutes
target-organ damage can be diagnosed on the basis
over a 24-hour period. The theory. is ‘that such
of a routine patient history and a physical
monitoring may provide useful additional
examination that includes an electrocardiogram, a
information about fluctuations in a patient’s blood
few blood tests, and a urinalysis. Additional testing
pressure as he or she goes about normal activities.
may be warranted in special cases, but often,
There is no scientific evidence, however, that such
expensive tests and procedures fail to provide
a test is better than periodic blood pressure
additional information that is of value in
measurements in a doctor’s office or pressures
determining effective treatment. As a general rule,
taken at various intervals at home. The National
a test is not needed unless it is likely to produce
High Blood Pressure Program concurs that such
information that alters therapy or helps determine
testing is not indicated for the vast majority of
prognosis. Some of the most overused tests in the
patients with high blood pressure.
management of high blood pressure include the
following.
EXERCISE TOLERANCE OR STRESS TEST
This examination entails taking a continuous
ECHOCARDIOGRAM
electrocardiogram and periodic blood pressure
In this test, high-frequency sound waves are
measurements while exercising, typically on a
“bounced off” the heart to create an image of its
treadmill or stationary cycle. Many doctors urge an
structures. Many doctors recommend
exercise test for patients with high blood pressure,
echocardiograms, which cost from $250 to as
presumably to detect possible coronary artery
much as $450, for hypertensive patients to
disease. An exercise test may be justified for
determine whether they have an enlarged heart or
patients who plan to embark on a rigid exercise
thickened heart muscle, a common consequence of
conditioning program, especially if they have other
long-term high blood pressure. It may be of
cardiovascular risk factors such as a family history
academic interest to know whether a patient has
of early heart attacks or elevated blood cholesterol,
an enlarged heart. In our experience, however, the
or if they smoke. But for most patients with mild to
knowledge is unlikely to alter the approach to
moderate high blood pressure, an exercise test is
treatment, especially in dealing with mild to
not needed to establish a diagnosis or to institute
moderate high blood pressure without evidence of
effective treatment. A typical exercise tolerance
heart failure.
test costs $200 to $300, an expense that cannot
be justified for most patients with high blood
pressure in the absence of other evidence of heart
24-HOUR B1OOD-PRESSURE MONITORING
disease.
This test, which costs $200 to $300, requires that a
patient wear a portable device that measures

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HIGH BLOOD PRESSURE
organs of high blood pressure) may warrant addi-
strep bacteria). But almost any chronic kidney dis-
tional testing. (See box, “Tests That Are Often Over-
order can result in elevated blood pressure. An ex-
used.”) In most cases, however, a diagnosis of high
ample is damage to the kidney’s blood vessels caused
blood pressure and its severity can be established
by diabetes.
accurately by repeated measurements with a sphyg-
As a rule, doctors will probably suggest specific
momanometer and a few simple tests.
tests of kidney function in cases of high blood pres-
sure that do not respond to conventional antihyper-
tensive (blood-pressure-lowering) therapy, especially
if a urinalysis shows protein in the urine—an indi-
cation of impaired kidney function. It should be
WHAT CAUSES HIGH BLOOD noted, however, that long-standing, poorly con-
PRESSURE?
trolled hypertension by itself can cause kidney dam-
age. In fact, about 25 percent of patients who require
kidney dialysis have renal failure that is due to hy-
In the majority of cases—over 90 percent—no spe-
pertension. This is especially true in the African-
cific cause for the elevated blood pressure can be
American population.
identified. In this case, the elevated blood pressure is
referred to as primary or essential hypertension.
RENOVASCULAR HYPERTENSION
Some researchers believe that this type of high blood
pressure may be due to hormonal factors relating to
The renal arteries, which carry blood to the two kid-
the handling of salt by the kidneys and/or to the elab-
neys, branch off from the abdominal aorta. A nar-
oration of certain substances that cause constriction
rowing in one or both of the renal arteries results in
of blood vessels. These are probably genetically de-
reduced blood flow to the kidneys. This prompts the
termined, but certain environmental factors, such as
kidneys to attempt to raise blood pressure in order
a high-salt, low-potassium diet and chronic stress,
to improve their own blood supply. To do this, the
may play some role.
kidneys increase their secretion of renin, an enzyme
In up to 10 percent of patients, high blood pressure
that, through a series of biochemical changes in the
may be a consequence of another disorder, or a side
kidneys and lungs, gives rise to a substance called
effect of medication. This type of hypertension is re-
angiotensin II This is a powerful vasoconstrictor, a
ferred to as secondary hypertension. lt is important
medical term used to describe substances that cause
to remember that these cases are relatively uncom-
blood vessels to narrow, or constrict. This constric-
mon. However, some of the more common causes of
tion results in increased blood pressure. This sub-
secondary hypertension include the following.
stance also increases the secretion of a hormone,
aldosterone, which leads to a retention of salt and
water—further increasing blood pressure.
Renovascular hypertension is rare (accounting for
KIDNEY DISORDERS
1 to 2 percent of all cases of hypertension), but it is
About 4 percent of all cases of high blood pressure
relatively more common in elderly persons who may
can be traced to some type of kidney (renal) disorder.
have widespread hardening of the arteries. It tends
The kidneys work in several ways to help regulate
to occur more frequently in smokers. It sometimes
blood pressure. For example, they are instrumental
occurs in children, as a result of infection or an in-
in regulating the body’s fluid volume and its balance
flammatory condition. In fact, renovascular hyper-
of sodium (salt) and water. If the kidneys conserve
tension is one of the more common causes of high
too much sodium, the body’s fluid volume increases.
blood pressure in young children, and should be sus-
In turn, this increased fluid volume puts an increased
pected in any youngster under the age of 10 to 12
burden on the heart to maintain an adequate flow of
with elevated blood pressure. Less commonly, re-
blood to tissues and causes blood pressure to rise.
novascular hypertension may be due to an inflam-
The kidneys also produce renin, an enzyme that plays
matory disorder that affects the muscles that encircle
a key role in regulating blood pressure. (See the dis-
the arteries and control their diameter. This type of
cussion below of renovascular hypertension.)
renovascular hypertension occurs more frequently
About 2 to 3 percent of all cases of high blood
in young women, although it is occasionally seen in
pressure are the result of recurrent kidney infection
men. It also tends to develop more frequently in
or a bout of nephritis (a kidney infection caused by
smokers than in nonsmokers.
155

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MAJOR CARDIOVASCULAR DISORDERS
Renovascular hypertension can be diagnosed by
of the adrenal gland called a pheochromocytoma.
studies in which a contrast dye is injected into a vein
This type of tumor, which is benign in about 90 per-
or artery to visualize the kidneys’ blood vessels on X-
cent of all cases, produces different types of hor-
ray film. Widening or opening up the narrowed renal
mones, specifically adrenaline-like substances. As
artery will often cure this type of high blood pressure.
noted earlier, these hormones are instrumental in the
The widening may be accomplished by angioplasty,
body’s fight-or-flight response. They serve to get us
a procedure in which a catheter with a balloon tip is
ready for emergencies or help us to exercise vigor-
inserted into the renal artery. The balloon is inflated
ously. Adrenaline increases the heart rate, elevates
at the site of narrowing to stretch the artery and in-
blood pressure, and helps increase blood flow to leg
crease blood flow. In some cases, surgery may be
muscles. In addition to elevated blood pressure, the
necessary to put in a bypass graft or bridge around
hormone elaborated by a pheochromocytoma may
the narrowed segment of the artery. The cure rate is
cause palpitations, tremors, clammy skin, jittery feel-
high in carefully selected cases.
ings, and facial and body sweating even in a cool
room. The symptoms, including high blood pressure,
may come and go.
ADRENAL TUMORS
The tumor usually develops on the adrenal glands,
The two adrenal glands, which rest atop each kidney,
but in fewer than 10 percent of even these rare cases,
secrete a number of hormones, including aldoste-
it arises elsewhere in the body, usually along the aorta
rone. This hormone is instrumental in maintaining
or spine, in the chest, or in the bladder. There are,
the body’s fluid and electrolyte or mineral balance by
however, only a few of these tumors reported yearly
regulating potassium secretion and prompting the
worldwide. If a pheochromocytoma is suspected, the
kidneys to conserve sodium. In rare instances (fewer
patient may be asked to collect his or her urine over
than 0.5 percent of all cases of hypertension), an
a 24-hour period; this is then analyzed for excessive
adrenal tumor develops and production of aldo-
amounts of adrenaline. X-ray studies or a CT scan
sterone is increased. The elevated aldosterone results
may be ordered to locate the tumor(s), which can then
in the body's excreting too much potassium and con-
be removed surgically. This removal usually cures the
serving too much sodium. The extra sodium increases
high blood pressure unless it has been present for
the body’s fluid volume, leading to high blood pres-
some time, in which case antihypertensive medica-
sure. These tumors are benign except in extremely
tion may still be needed to keep blood pressure within
rare instances.
normal limits.
This type of hypertension is rare, but should be
suspected if a person develops high blood pressure
and experiences other symptoms, such as muscle
weakness, thirst, and excessive urination. Younger
DRUGS
women are more susceptible to this disease than
Some drugs that are used for other conditions can
other people. But one should also keep in mind that
raise blood pressure. Examples include birth control
excessive thirst and urination may be symptoms of
pills, the use of which may result in a small rise of 5
other illnesses, such as diabetes. A diagnosis can be
to 10 mm Hg in many women and a greater increase
established by blood and urine studies and a com-
in about 1 in 30 to 50 women. The use of cortisone
puted tomography (CT) scan of the adrenal glands.
or other steroid medications and of certain nonpre-
CT scan is an examination that uses a computer to
scription drugs, including some cold remedies, diet
create a cross-sectional view of internal organs from
pills, arthritis medications such as the nonsteroidal
multiple X-rays. Removal of the adrenal tumor usually
anti-inflammatory agents Indocin, Naprosyn, etc.,
cures the high blood pressure. If, however, excessive
and nasal decongestants, may also increase blood
aldosterone secretion is due to overactive adrenal
pressure. Glycyrrhizic acid, an ingredient in natural
glands instead of a specific tumor, medication can be
licorice candy, can also raise blood pressure if
prescribed to block the hormone’s action.
consumed in large quantities. In almost all of
these cases, blood pressure usually returns to nor-
mal when the causative substance is stopped. In
PHEOCHROMOCYTOMA
some instances, the use of one of these medications
This is another very rare type of secondary hyper-
may unmask a previously undiagnosed case of
tension that is related to a different type of a tumor
hypertension.

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HIGH BLOOD PRESSURE
HYPERTENSION IN PREGNANCY
tassium. The exact mechanisms by which these fac-
There is a type of hypertension that may develop in
tors raise blood pressure have not been clearly
the last three months of pregnancy as part of toxemia
identified; some people appear to be more susceptible
of pregnancy. (See Chapter 19.) Since blood pressure
to them than others. For example, a high-salt diet may
levels in pregnancy are usually on the low side of
raise blood pressure only in people who have a ge-
normal (90–110/70–75), any increase to levels of
netic tendency to conserve sodium. Similarly, many
above 135-140/85–90 should be considered as ele-
people who consume excessive amounts of alcohol
vated, and some treatment should be instituted.
have normal blood pressures.
WHO DEVELOPS HIGH BLOOD LONG-TERM EFFECTS
PRESSURE?
Hypertension is often referred to as the silent killer
because it usually does not produce definite symp-
High blood pressure develops in all social and eco-
toms until it reaches an advanced stage. The first in-
nomic groups, and affects both men and women. It
dication of high blood pressure maybe an event such
generally begins in adulthood between the ages of 35
as a stroke or heart attack. Untreated high blood
and 50, although it also occurs to a lesser extent
pressure is the major cause of strokes; it is also one
among children and younger adults. Hypertension is
of the major risk factors for a heart attack. Even be-
rather uncommon in preadolescent children, but
fore one of these events occurs, however, and even
blood pressure should be checked at age 2 to 3 and
though a person may feel well, hypertension, if un-
again at age 13 to pick up the rare cases. The younger
treated, is taking its toll on vital organs throughout
the age, the more probable that a secondary cause of
the body. Fortunately, as noted earlier, the conse-
hypertension will be found. Some people are more
quences of hypertension can be largely prevented by
susceptible to hypertension than others, including:
lowering high blood pressure into the normal range
and keeping it there.
q
African-Americans. Not only are blacks twice
as likely as whites to develop hypertension, but
their disease is also more severe.
ARTERIES
q
People with a family history of the disease. Ba-
bies born to parents who have hypertension
High blood pressure speeds up the process of hard-
tend to have higher-than-average or more vari-
ening of the arteries in both large blood vessels such
able blood pressures throughout infancy and
as the aorta and its major branches and the smaller
childhood, and are more likely to develop hy-
arteries. The increased pressure on the inner walls
pertension at a relatively early age. This ten-
of blood vessels makes them more vulnerable to a
dency strongly suggests that there is a genetic
buildup of fatty deposits, a process called athero-
basis for at least some cases of high blood pres-
sclerosis. This blood-vessel damage may not produce
sure. It does not mean, however, that if both
symptoms until it reaches an advanced stage, and
parents have hypertension the offspring will al-
then symptoms or findings will depend upon the site
ways develop high blood pressure.
of the atherosclerosis. For example, angina, the chest
pains that are a sign that the heart muscle is not get-
q
People with diabetes.
ting enough blood, is caused by severely narrowed
q
People who are overweight.
and clogged coronary arteries. Narrowed arteries in
the lower legs can make it painfuI and difficult to
Epidemiological, or population, studies suggest a
walk, a condition called intermittent claudication. (See
number of other factors that may increase the risk of
Chapter 17.)
having high blood pressure. These include consum-
Clots, or thrombi as they are known medically, are
ing large amounts of salt (sodium) and alcohol (more
more likely to form in arteries that have been nar-
than the equivalent of 3 to 4 ounces of alcohol daily),
rowed by deposits of fatty material. A clot in a cor-
smoking cigarettes, and following a diet low in po-
onary artery (a coronary thrombosis) can result in a

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MAJOR CARDIOVASCULAR DISORDERS
heart attack; one in the carotid artery or a blood ves-
BRAIN
sel in the brain (a cerebral thrombosis) can cause a
The circulatory system is designed to ensure a steady
stroke.
supply of blood and oxygen to the brain. When the
High blood pressure that persists untreated for
body senses a decrease in blood flow to the brain, it
many years also increases the likelihood of an aneu-
takes immediate action to remedy the situation by
rysm, the ballooning out of a weakened segment of
raising blood pressure and by diverting blood from
an artery (similar to a blister that forms over a weak-
other organs and sending it to the head. The heart
ened spot of a balloon). In time, these aneurysms may
speeds up and vessels in the abdomen and legs con-
rupture, often with life-threatening consequences.
tract, allowing more blood to get to the brain. If the
For example, a ruptured aneurysm in the brain can
carotid artery and other blood vessels that supply
cause a cerebral hemorrhage and a stroke. A rup-
blood to the brain become clogged with fatty depos-
tured aneurysm of the aorta can lead to fatal internal
its, vital blood flow to the brain maybe diminished.
hemorrhaging if it is not repaired immediately.
In such a situation, the risk of a stroke increases. For
High blood pressure also damages the small ar-
example, a stroke may occur if a portion of a vessel
teries, but in a different reamer. The muscles that
is blocked by a clot. Blood flow to a portion of the
form the lining of these vessels become thickened,
brain ceases and the tissue supplied by the clotted
constricting the vessels and obstructing blood flow
vessel is damaged. More seriously, a stroke may be
through them. If this happens to the arterioles in the
caused by a cerebral hemorrhage. A stroke may oc-
kidney, it can lead to progressive renal damage. Sim-
cur when an artery that is weakened by long-term
ilarly, a thickening and hemorrhaging of the tiny ar-
hypertension or atherosclerosis develops an aneu-
teries in the eyes can result in a loss of vision.
rysm and ruptures.
Often, the blockage is temporary, causing only a
brief interruption of blood flow. This is called a tran-
sient ischemic attack (TIA) or ministroke. (See box in
HEART
Chapter 18, “Common Warning Signs of Stroke and
Transient Ischemic Attack.”) Although the episode
The heart is one of the major target organs of long-
usually passes within minutes, it warrants medical
term hypertension. Hypertension forces the heart to
attention, because TIAs may be precursors of full-
work harder in order to sustain an adequate blood
blown strokes. In addition, repeated TIAs may result
flow to the tissues, resulting in an enlarged heart. The
in some loss of mental function, known as 17A de-
heart is composed mostly of muscle tissue, and any
mentia. If portions of the brain are repeatedly sub-
muscle that is strained will become larger (witness
jected to periods of lack of oxygen, brain tissue may
what happens to the biceps muscles of weight lifters).
be permanently injured. (See Chapter 18.)
In the early stages, the enlarged heart muscle has the
added strength needed to pump blood against the
increased pressure in the arteries. In time, however,
the enlarged heart may become stiff and weak, and
KIDNEYS
unable to pump efficiently. This can lead to heart fail-
Each kidney contains a million or more tiny filtering
ure, a condition in which the heart is unable to pump
units called nephrons. Each day, more than 400 gal-
enough blood to meet the body’s needs. Just a few
lons of blood flow through the kidneys, where waste
decades ago, heart failure usually progressed rapidly,
products are filtered out and excreted in the urine
with increasing disability and eventual death. Today,
and nutrients and other useful substances are re-
however, it can generally be controlled with medi-
turned to the bloodstream. Sustained high blood
cations, enabling most patients to lead normal lives
pressure forces the kidneys to work even harder. The
for many years. And most important, recent studies
increased blood pressure may eventually damage
show that with effective treatment of high blood pres-
some of the tiny blood vessels within the kidney and
sure, much of the heart enlargement actually can be
reduce the amount of blood available to the filtering
reversed. In the 1940s and early 1950s, the most com-
units. In time their ability to filter the blood efficiently
mon cause of heart failure was hypertension. Today
is reduced. Protein may be excreted in the urine
this complication is extremely rare—high blood pres-
rather than returned to the bloodstream because of
sure is being effectively treated, and heart enlarge-
damage to the delicate excreting mechanism, and
ment and heart failure are actually being prevented.
waste products that are normally eliminated from the

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Document Outline

• INTRODUCTION
• WHAT IS HIGH BLOOD PRESSURE OR HYPERTENSION
• WHAT CONSTITUTES HIGH BLOOD PRESSURE?
• STEPS IN ESTABLISHING A DIAGNOSIS OF HIGH BLOOD PRESSURE
• WHAT CAUSES HIGH BLOOD PRESSURE?
  • KIDNEY DISORDERS
  • RENOVASCULAR HYPERTENSION
  • ADRENAL TUMORS
  • PHEOCHROMOCYTOMA
  • DRUGS
  • HYPERTENSION IN PREGNANCY
• WHO DEVELOPS HIGH BLOOD PRESSURE?
• LONG-TERM EFFECTS
  • ARTERIES
  • HEART
  • BRAIN
  • KIDNEYS
  • EYES
• TREATMENT OF HIGH BLOOD PRESSURE
  • REDUCING SODIUM INTAKE
  • MAINTAINING A MODERATE ALCOHOL INTAKE
  • LOSING EXCESS WEIGHT
  • INCREASING PHYSICAL ACTVITY
• ANTIHYPERTENSIVE DRUGS
  • DIURETICS
  • BETA BLOCKERS
  • CALCIUM-CHANNEL BLOCKERS
  • ANGIOTENSIN CONVERTING ENZYME (ACE) INHIBITORS
  • ALPHA-BLOCKING DRUGS
  • VASODILATORS
  • PERIPHERAL ADRENERGIC ANTAGONISTS
  • CENTRALLY ACTING DRUGS
• SUMMARY

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