Introduction
Some 7 million Americans suffer from
coronary heart disease
(CHD), the most common form of heart disease.
This
type of heart disease is caused by a narrowing
of the coronary arteries that
feed the heart.
CHD is the number one killer of both men and women
in
the U.S. Each year, more than 500,000
Americans die of heart attacks caused
by CHD.
Many of these deaths could be prevented because CHD is
related
to certain aspects of lifestyle. Risk factors for
CHD include high blood
pressure, high blood cholesterol,
smoking, obesity, and physical
inactivity--
all of which can be controlled.
Although medical
treatments for heart disease have come
a long way, controlling risk factors
remains the key
to preventing illness and death from CHD.
Who Is at
Risk for CHD?
Risk factors are conditions that increase your risk of
developing
heart disease. Some can be changed and some cannot.
Although
these factors each increase the risk of CHD,
they do not describe all the
causes of the disease;
even with none of these risk factors, you might still
develop CHD.
Controllable
Uncontrollable
High blood
pressure
Gender
High blood cholesterol
Heredity (family history of
CHD)
Smoking
Age
Obesity
Physical
Activity
Diabetes
Stress*
* Although stress may be a risk factor for
CHD,
scientists still do not know exactly how
stress might be involved in
heart disease.
What Is CHD?
Like any muscle, the heart needs a
constant supply of oxygen
and nutrients that are carried to it by the blood
in the coronary arteries. When the coronary arteries become
narrowed or
clogged and cannot supply enough blood to the heart,
the result is CHD. If
not enough oxygen-carrying blood
reaches the heart, the heart may respond
with pain called angina.
The pain is usually felt in the chest or
sometimes
in the left arm and shoulder. (However, the same inadequate
blood
supply may cause no symptoms, a condition called silent
angina.)
When the blood supply is cut off completely, the result
is a
heart attack. The part of the heart that
does not receive oxygen begins to
die,
and some of the heart muscle may be permanently damaged.
What
Causes CHD?
CHD is caused by a thickening of the inside walls
of the
coronary arteries. This thickening, called
atherosclerosis, narrows the
space through which blood can flow,
decreasing and sometimes completely
cutting off the
supply of oxygen and nutrients to the
heart.
Atherosclerosis usually occurs when a person has
high levels
of cholesterol, a fat-like substance,
in the blood. Cholesterol and
fat,
circulating in the blood, build up on the
walls of the arteries. The
buildup narrows
the arteries and can slow or block
the flow of blood. When
the level of
cholesterol in the blood is high, there is a greater
chance
that it will be deposited onto the artery walls.
This process begins in most
people during childhood
and the teenage years, and worsens as they get
older.
In addition to high blood cholesterol, high blood pressure
and
smoking also contribute to CHD. On the average,
each of these doubles your
chance of developing heart disease.
Therefore, a person who has all three
risk factors is
eight times more likely to develop heart disease
than
someone who has none. Obesity and physical
inactivity are other factors that
can lead to CHD.
Overweight increases the likelihood of developing high
blood
cholesterol and high blood pressure, and physical
inactivity
increases the risk of heart attack. Regular exercise,
good
nutrition, and smoking cessation are key
to controlling
the risk factors
for CHD.
What Are the Symptoms of CHD?
Chest pain (angina) or
shortness of breath may be the
earliest signs of CHD. A person may feel
heaviness, tightness,
pain, burning, pressure, or squeezing, usually behind
the breastbone
but sometimes also in the arms, neck, or jaws.
These signs
usually bring the patient to a doctor
for the first time. Nevertheless, some
people have
heart attacks without ever having any of these
symptoms.
It is important to know that there is a wide range
of
severity for CHD. Some people have no symptoms at all,
some have mild
intermittent chest pain, and some have mild
intermittent chest pain, and some
have more pronounced and
steady pain.Still others have CHD that is severe
enough
to make normal everyday activities difficult.
Because CHD
varies so much from one person to another,
the way a doctor diagnoses and
treats CHD will also vary a lot.
The following descriptions are general
guidelines to
some tests and treatments that may or may not be
used,
depending on the individual case.
Are There Tests for
CHD?
There is no one simple test--some or all of
the following
procedures may be needed. These diagnostic
procedures are used to establish
CHD, to determine
its extent and severity, and to rule
out other possible
causes of the symptoms.
After taking a careful medical history and doing
a
physical examination, the doctor may use some
tests to see how advanced
the CHD is.
The only certain way to diagnose and
assess the extent of CHD
is coronary
angiography (see below); other tests can
indicate a problem
but do not show exactly where it is.
An examination for CHD may include
the following tests:
An electrocardiogram (ECG or EKG) is a graphic
record
of the electrical activity of the heart
as it contracts and
rests.
Abnormal heartbeats and some areas of damage,
inadequate blood
flow, and heart enlargement
can be detected on the records.
A stress
test (also called a treadmill test or exercise ECG)
is used to record the
heartbeat during exercise.
This is done because some heart problems only
show
up when the heart is working hard.
In the test, an ECG is done
before,
during, and after exercising on a treadmill;
breathing rate and
blood pressure may be
measured as well. Exercise tests are useful
but are
not completely reliable; false positives
(showing a problem where none
exists) and false negatives
(showing no problem when something is wrong) are
fairly common.
Nuclear scanning is sometimes used to show
damaged
areas of the heart and expose problems with
the heart's pumping
action. A small amount of radioactive
material is injected into a
vein,
usually in the arm. A scanning camera records
the nuclear material
that is taken up by heart muscle
(healthy areas) or not taken up (damaged
areas).
Coronary angiography (or arteriography) is a
test used to
explore the coronary arteries.
A fine tube (catheter) is put into an
artery
of an arm or leg and passed through
the tube into the arteries of
the heart.
The heart and blood vessels are then
filmed while the heart
pumps. The picture
that is seen, called an angiogram or
arteriogram, will
show problems such
as a blockage caused by atherosclerosis.
How Is CHD
Treated?
CHD is treated in a number of ways,
depending on the
seriousness of the disease.
For many people, CHD is managed with
lifestyle
changes and medications. Others with
severe CHD may need surgery. In any
case,
once CHD develops, it requires lifelong management.
What Kind of
Lifestyle Changes Can Help a Person with CHD?
Although great advances
have been made in treating
CHD, changing one's habits remains the single most
effective way to stop the disease from progressing.
If you know that
you have CHD, changing your
diet to one low in fat, especially
saturated
fat, and cholesterol will help reduce high
blood cholesterol, a
primary cause of atherosclerosis.
In fact, it is even more important to keep
your cholesterol low after a heart attack to help
lower your risk of
having another one.
Eating less fat should also help you lose weight.
If
you are overweight, losing weight
can help lower blood cholesterol and
is
the most effective lifestyle way to
reduce high blood pressure, another
risk factor for atherosclerosis and heart disease.
People with CHD
can also benefit from exercise.
Recent research has shown that even moderate
amounts
of physical activity are associated with lower
death rates from
CHD. However, people with
severe CHD may have to restrict their
exercise
somewhat. If you have CHD, check with your doctor
to find out
what kinds of exercise are best for you.
Smoking is one of the three
major risk factors for CHD.
Quitting smoking dramatically lowers the risk of
a
heart attack and also reduces the risk of a second
heart attack in
people who have already had one.
What Medications Are Used to Treat
CHD?
Medications are prescribed according to the nature
of the
patient's CHD and other problems.
The symptoms of angina can generally be
controlled by "beta-blocker" drugs that decrease
the workload on the
heart, by nitroglycerine
and other "nitrates" and by
"calcium-channel
blockers" that relax
the arteries, and by other classes of drugs.
The
tendency to form clots is reduced
by aspirin or by other platelet inhibitory
and anticoagulant drugs.
Beta-blockers are given to decrease
the
recurrence of heart attack. For those with
elevated blood cholesterol
that is unresponsive to dietary
and weight loss measures,
cholesterol-lowering
drugs may be prescribed, such as
lovastatin,
colestipol,cholestyramine, gemfibrozil, and niacin.
Impaired
pumping function of the heart may
be treated with digitalis drugs or ACE
inhibitors.
If these is high blood pressure or fluid
retention, these
conditions are also treated.
Ask your doctor which medication you are
taking,
what it does, and whether there are any
side effects. Knowing
more about this will help you
stick to the schedule that has been prescribed
for you.
What Types of Surgery Are Used to Treat CHD?
Many
patients can control CHD with lifestyle changes
and medication. Surgery may
be recommended
for patients who continue to have frequent
or disabling
angina despite the use of
medications, or people who are found to
have
severe blockages in their coronary arteries.
Coronary angioplasty
or balloon angioplasty begins
with a procedure similar to that
described
under angiography. However, the catheter positioned
in the
narrowed coronary artery has a tiny
balloon at its tip. The balloon is
inflated and
deflated to stretch or break open the
narrowing and improve
the passage for blood flow.
The balloon-tipped catheter is then
removed.
Strictly speaking, angioplasty is not surgery.
It is done
while the patient is awake
and may last 1 to 2 hours. If angioplasty
does
not widen the artery or if complications
occur, bypass surgery may be
needed.
In a coronary artery bypass operation,
a blood vessel, usually
taken from the leg or chest,
is grafted onto the blocked artery,
bypassing
the blocked area. If more
than one artery is blocked, a bypass
can be
done on each. The blood can
then go around the obstruction
to supply the
heart with enough
blood to relieve chest pain.
Bypass surgery relieves
symptoms of heart
disease but does not cure it.
Usually you will need to
make a number of
changes in your lifestyle after the operation.
If your
normal lifestyle includes smoking,
a high-fat diet, or no
exercise,
changes are advised.
Several experimental catheter-surgical
procedures
for unblocking coronary arteries are under
study; their safety
and effectiveness
have not yet been established. They
include:
Atherectomy, a procedure in which surgeons shave off
thin strips
of the plaque
blocking the artery and remove these strips.
Laser
angioplasty; instead of using
a balloon to open up the blocked
artery,
doctors insert a catheter with a laser tip
that burns or breaks
down the plaque.
Insertion of a stent, a metal coil that
can be
permanently implanted in a narrowed
part of an artery to keep it propped
open.
For further information contact:
National Heart Lung, and
Blood Institute (NHLBI)
Information Center
P.O. Box 30105
Bethesda MD
20824-0105
Acknowledgement:
U.S. Department of Health and Human
Services
Public Health Service
National Institutes of Health
The
National Heart, Lung, and Blood Institute
NIH Publication No. 93-2265
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