Overview
Hypertension (high blood pressure) is an
endemic condition in the United States and throughout the
world. In fact, over half of all persons age 65 and older
develop hypertension. Common symptoms experienced by
persons with hypertension include sweating, palpitations,
headaches, and dizziness.
Numerous scientific studies have
conclusively determined that high systolic and/or
diastolic blood pressure increases the risk for developing
disabling and potentially deadly medical conditions.
Generally, the higher the blood pressure, the greater the
risk. Persons with high diastolic blood pressure have more
than 10 times the risk for developing stroke as persons
with lower, normal diastolic blood pressure.
Blood Pressure
Blood pressure is the measurement of the pressure produced
by the flow of blood in the arteries of the body. Two
blood pressures are measured, systolic blood pressure and
diastolic blood pressure. In a blood pressure reading of,
say, one hundred and thirty over eighty (130/80 mm Hg),
one hundred and thirty refers to systolic blood pressure
and eighty refers to diastolic blood pressure. Systolic
pressure is measured while the heart contracts,
actively pumping blood into the arteries of the body.
Diastolic pressure is measured while the heart rests
between beats.
High Blood Pressure (Hypertension)
There is a fairly wide range of systolic and diastolic
blood pressures considered to be within the normal range.
In general, systolic pressures above 140 mm Hg and/or
diastolic pressures above 90 mm Hg are considered to be
above the normal range. Patients whose systolic and/or
diastolic blood pressures are consistently above the
normal range are said to have hypertension, or high blood
pressure.
There is overwhelming evidence that this
condition increases the risk for stroke, heart attack
(myocardial infarction), congestive heart failure, and
kidney failure. Dozens of studies show that treating high
blood pressure significantly decreases the risk for
developing these dreaded and potentially fatal conditions.
Unfortunately, many people are unaware that they have
hypertension, and only about half those with the condition
are being treated for it. Most disheartening, only 27% of
all hypertensive patients in the United States are being
treated adequately.
Hypertension and the Elderly
Over half of all persons age 65 and older will have high
blood pressure. In many, only the systolic blood pressure
will be elevated. This is often refered to as isolated
systolic hypertension. In the past, little attention
was paid to this finding of isolated systolic hypertension
in elderly patients. It is now clearly recognized that
isolated systolic hypertension increases the risks of
stroke and other medical conditions and that treating
these patients is at least as beneficial, if not more so,
as treating younger persons with high blood pressure.
Several studies have addressed this issue. These studies
found that treating high systolic blood pressure in older
patients significantly decreased the risks of stroke,
heart attack, and cardiovascular death. Therefore, older
patients with high blood pressure, even if only the
systolic blood pressure is elevated, merit treatment at
least as much as younger patients do, and the fact that
such patients are "older" should not be used as an excuse
not to treat them.
The National High Blood Pressure Education
Program Working Group emphasizes that blood pressure
should be reduced "slowly and cautiously" in older
patients. Lower initial doses of medications should
generally be used, and increases in the doses of
medications prescribed should likewise be made in smaller
increments.
Causes
In most people, no specific cause of high
blood pressure is identified. It appears to be a distinct
entity, perhaps due in part to a genetic predisposition
for hypertension. The probability of developing this
condition increases with age. As mentioned previously,
more than half of all persons age 65 have hypertension.
In approximately 5% of patients, a
secondary cause exists. Secondary causes include certain
types of kidney disease, abnormal functioning of certain
glands (adrenal glands, thyroid gland, parathyroid
glands), chronic intake of certain substances and
medications (e.g., alcohol and steroids), and the presence
of a rare tumor (e.g., pheochromocytoma, which secretes
adrenaline-like substances).
Treatment
Several studies have demonstrated that
treating patients to lower their blood pressure
significantly decreases their risk for developing
disabling and potentially deadly medical conditions.
The goal of treatment for most patients is
to lower the systolic blood pressure below 140 mm Hg and
the diastolic blood pressure below 90 mm Hg. In some
patients, such as those with diabetes, it is recommended
that blood pressure be lowered even further, to a systolic
pressure below 130 mm Hg and a diastolic pressure below 85
mm Hg.
Treatment for high blood pressure involves
life-style modification
and
drug therapy (or
pharmacological therapy) .
Life style modification
In some patients, particularly those whose blood pressure
is moderately elevated, life style modifications alone may
achieve treatment goals. Patients who require
pharmacological therapy
may reduce the number and doses of medications through
life style modification. The following modifications in
diet and physical activity should be discussed with a
doctor or health care provider.
-
Weight
loss.
Overweight patients can reduce blood pressure by losing
weight. Gradual weight loss through modified calorie
intake and increased physical activity is a good
approach. A goal of losing 10-15 pounds is reasonable
for many patients.
-
Physical activity.
Regular, moderate aerobic exercise can modestly decrease
blood pressure and has many other beneficial effects. A
program of gradually increased activity is most prudent,
such as taking a brisk, 20-30 minute walk, 3-5 times a
week. All persons with chest pain (angina) and known or
suspected heart disease should talk to their doctor
before beginning a exercise program.
-
Salt
(sodium chloride) restriction.
Excessive salt intake can contribute to hypertension in
some people. Even modest restriction of salt may
decrease blood pressure. Generally, many doctors advise
those with high blood pressure to avoid salty food and
to limit daily sodium intake to no more than
approximately 2.4 grams. (Doctors use the words "salt"
and "sodium" interchangeably.)
-
Limited alcohol consumption.
Moderate alcohol intake (one or two glasses of an
alcoholic beverage a day) does not appear to cause
hypertension; however, chronic heavy alcohol use
elevates blood pressure. This is the most common
reversible cause of high blood pressure. Therefore,
hypertension patients who drink alcohol excessively
should discuss this issue with their health care
provider and reduce their consumption of alcohol.
Medications
There are a variety of medications used to
treat high blood pressure called antihypertensive agents.
Which agent a patient is started on depends on numerous
factors, including ease of use, side effects, and
coexisting medical conditions that might dictate
preferential use of one agent over another.
Generally, an antihypertensive agent is
started at a relatively low dose, and the response to it
is assessed over the course of several weeks. If the blood
pressure remains elevated, the dose of the medication is
gradually increased.
When treatment with relatively high doses
of an antihypertensive medication fails to lower blood
pressure to target levels, two options are possible : (1)
that particular medication may be discontinued and a
different class of antihypertensive medication begun, or
(2) a second class of medication may be added to the first
agent. The second approach is often used because different
classes of antihypertensive agents work in different ways
to lower blood pressure, and the actions of one agent may
complement the actions of the second agent. In some
patients, it may be necessary to add a third agent.
Most of the newer medications are taken
once or twice a day. They all have side effects, but most
are well tolerated by patients.
Diuretics ("water pills").
Diuretics increase the kidneys' excretion of salt (sodium)
and water, decreasing the volume of fluid in the
bloodstream and the pressure in the arteries. Diuretics
are the oldest and most studied antihypertensive agents.
One of the most commonly used diuretic
agents is hydrochlorothiazide (HydroDiuril®, Microzide®).
Other diuretics used to treat hypertension include the
following:
-
Acetazolamide (Diamox®)
-
Indapamide (Lozol®)
-
Metolazone (Zaroxolyn®)
-
Spirnolactone (Aldactone®)
-
Torsemide (Demadex®)
-
Triamterene (Dyrenium®)
Combination medications that contain both a
diuretic and a different class of antihypertensive agent
are being produced.
The main side effect of these agents
is increased frequency of urination. Another side effect
is increased urinary excretion of potassium. Because of
this, doctors monitor blood potassium levels when
initiating therapy and periodically thereafter. Patients
who have low potassium levels are encouraged to eat foods
rich in potassium, such as bananas, or may be prescribed a
potassium supplement.
Beta blockers.
This class of medications decreases the vigor of the
heart's contractions. By decreasing the force used to pump
blood into the arteries, the medications decrease blood
pressure. In addition to lowering blood pressure, beta
blockers have multiple beneficial effects (including
prolonged life) in patients with coronary artery disease,
patients who have had myocardial infarction (heart
attack), and many patients with congestive heart failure (CHF).
Commonly used beta blockers include the following:
-
Atenolol (Tenormin®)
-
Bisoprolol (Zebeta®)
-
Carvedilol (Coreg®)
-
Metoprolol (iLopressor®, Toprol SL®)
-
Timolol (Blockadren®)
Another beta blocker, labetolol (Normodyne®,
Trandate®) has alpha blocker properties that dilate the
arteries and lower blood pressure.
Potential side effects of the beta
blockers are slowing the heart rate excessively, worsening
heart failure (careful long-term use has been shown to
frequently provide beneficial effects in patients with CHF),
and, rarely, contributing to confusion, depression, and
impotence.
Calcium channel blockers.
This class of agents lowers blood pressure in several
ways. Two of these agents, diltiazem (Cardizem®) and
verapamil (Calan®, Covera HS®, Isoptin®, Veralan®) act in
part like the beta blockers, decreasing the vigor of the
heart's contractions. By decreasing the force with which
blood is pumped into the arteries, they decrease blood
pressure. These agents also dilate (open up) arteries,
decreasing resistance to blood flow, thereby decreasing
blood pressure.
The newer calcium channel blockers
primarily dilate the arteries and have little effect on
the forcefulness of the heart's contractions. These
include:
-
Amlodipine (Norvasc®)
-
Felodipine (Plendil®)
-
Idradipine (DynaCirc®)
-
Nicardipine (Cardene®)
-
Nisoldipine (Sular®)
One of these newer agents has been shown to
decrease the risk for stroke in older patients with high
systolic blood pressure.
The calcium channel blockers have potential
side effects. Because diltiazem and verapamil
decrease the force of the heart's contractions, they may
occasionally worsen congestive heart failure symptoms.
Verapamil may occasionally cause constipation, especially
in elderly patients. Many of the calcium channel blockers
cause headache and edema (swelling) in the ankles and
feet.
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ACE inhibitors.
These medications help dilate the arteries, thereby
decreasing resistance to blood flow and consequently
decreasing blood pressure. They have many other beneficial
effects and are used to treat patients with congestive
heart failure. Many studies have shown that treatment of
heart failure patients with ACE inhibitors improves heart
failure symptoms, decreases the chance of future
hospitalizations, decreases the risk for future heart
attack, and decreases the risk of death from heart
failure.
There are many ACE inhibitors available,
including the following:
-
Benazepril (Lotensin®)
-
Captopril (Capoten®)
-
Enalapril (Vasotec®)
-
Fosinopril (Monopril®)
-
Lisinopril (Prinivil®, Zestril®)
-
Quinapril (Accupril®)
-
Ramipril (Altace®)
-
Trandolapril (Mavik®)
ACE inhibitors are usually tolerated well,
but there are potential side effects. Approximately
10% of patients develop a chronic nonproductive cough.
Rarely, ACE inhibitors produce a sudden swelling of the
lips, face, and cheek areas in an allergic reaction that
can occur at any time during therapy. If an allergic
reaction occurs, medical attention should be sought
immediately. Because ACE inhibitors can affect kidney
function and raise the potassium level, doctors monitor
these during the first several weeks of therapy and
periodically thereafter.
Angiotensin-receptor blockers (ARBs).
This is a new class of medications, which are similar in
some respects to ACE inhibitors. Like ACE inhibitors, they
help dilate arteries, lowering blood pressure and making
it easier for the heart to pump blood throughout the body.
Also, like ACE inhibitors, they can improve congestive
heart failure symptoms, decrease the chances of future
hospitalizations for heart failure, and prolong life.
Ongoing studies are comparing the effects of ARBs with the
ACE inhibitors and are investigating the use of both in
patients with heart failure. Currently available ARBs
include:
-
Candesartan (Atacand®)
-
Irbesartin (Avapro®)
-
Losartin (Cozaar®)
-
Telmisartin (Micardis®)
-
Valsartan (Diovan®)
The ARBs are generally taken once a day and
do not commonly produce significant side effects. Rarely,
they interfere with or worsen kidney function.
Direct-acting vasodilators.
The medication hydralazine more or less directly dilates
the arteries in the body, lowering blood pressure.
Hydralazine is sometimes used in combination with
isosorbide dinitrate to treat patients with congestive
heart failure.
Centrally acting agents.
These antihypertensive agents affect the central nervous
system (brain) to decrease blood pressure. Such
medications include clonidine (Catapres®) and methyldopa (Aldomet®).
Because these drugs act directly on the brain, they
occasionally cause drowsiness, depression, and other
symptoms.
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