How To Stave Off
Disease
As these
descriptions of the various forms of heart disease indicate,
much is known about the causes, often referred to as
“risk factors.” Some—such as heredity, age,
race, and gender—cannot be controlled. But many others
are controllable and there are many ways you can prevent
heart disease.
Basically, heart
disease prevention falls into two categories: lifestyle or
behavior modification; and pharmacological intervention, or
use of medications.
Lifestyle
Cigarette Smoking. The single most important thing you
can do to prevent heart disease is not smoke. If you do
smoke, you should stop; your risk of heart disease will begin
to decline, reaching the level of a non-smoker after 5 to 10
years.
The higher risk of
cardiovascular disease in women due to smoking is similar to
that of men. Low tar and low nicotine cigarettes seem to be
no less harmful than regular cigarettes. A range of studies
has shown that women who smoke are from 2 to 6 times more
likely than non-smokers to develop heart disease. Statistics
from the Nurses' Health Study, a large, ongoing survey of
women's health, show that half of the cases of heart disease
in women aged 30 to 55 can be linked to cigarette
smoking.
The most dramatic
increase in risk is in women who smoke and use oral
contraceptives. Tests have shown that these women are
20 to
30 times more likely to suffer heart disease and
stroke than women who do neither. However, most of the data
on this subject came from studies done when participants were
taking a much higher dose of estrogen than is currently
prescribed. As a result, further research is needed on the
effects of today's lower-dose oral contraceptives.
Cigarettes act in a
number of ways to increase your risk of heart disease.
Smoking causes thickening of the blood, which can lead to
clots. It raises the level of carbon monoxide in the blood,
robbing the heart and other tissues of needed oxygen. The
nicotine in tobacco also constricts the coronary arteries,
raising blood pressure, and causing the heart to work harder.
Thus smoking increases the amount of oxygen that the heart
needs, while at the same time decreasing the amount it
gets.
High blood pressure contributes to heart disease
because it makes the heart work harder. Controllable factors
that contribute to high blood pressure include overweight,
lack of exercise, excessive salt intake, and cigarette
smoking. It follows logically that losing weight, exercising,
limiting salt in your diet, and stopping smoking can reduce
blood pressure to healthier levels. Living with continually
high levels of stress is also linked to high blood
pressure.
The first thing you
can do to control your blood pressure is to know what it is.
Although you can measure blood pressure with a
sphygmomanometer at the supermarket or shopping mall, it is a
good idea to discuss the implications of your blood pressure
level with your doctor.
Cholesterol, a very popular topic these days, is a
substance that circulates in the blood, and is essential for
functions such as producing some hormones (including
estrogens) and building a protective membrane for our cells.
We get some from what we eat, but mostly it is manufactured
in the liver.
Cholesterol travels
through the bloodstream attached to lipoproteins, compounds
composed of fats (lipids), proteins, and triglycerides. There
are four kinds of lipoproteins, classified according to their
weights: very low density (VLDL), low density (LDL), high
density (HDL) and very high density (VHDL). You've probably
heard about “good” and “bad” cholesterol.
The good is HDL, which is associated with a cleansing effect
in the blood; and the bad is LDL, which leaves deposits on
the interior walls of the arteries, hampering the flow of
blood and leading to atherosclerosis.
In general, a total
cholesterol count of less than 200 milligrams per deciliter
of blood is viewed as healthy; if that count reaches 240, the
risk of heart disease doubles. However, most of the studies
that have drawn this conclusion have been done on men. One
study focusing on women has found that the most important
factor predicting coronary artery disease in women is
not total cholesterol, but the ratio of HDL to total
cholesterol: The higher your HDL, the less likely you are to
get heart disease.
Triglycerides are
another kind of fat in your bloodstream, but elevated
triglycerides are not necessarily associated with an
increased risk of heart disease. Triglyceride levels
fluctuate widely throughout the day, depending on what you
eat. They may, however, be associated with high cholesterol
levels.
You can do a great
deal to achieve a healthier cholesterol level by controlling
your diet. Reducing cholesterol and fat intake, particularly
saturated fats, will lower total cholesterol levels.
Monounsaturated fatty acids (such as those found in olive and
canola oil) tend to raise HDL, so those are the healthiest
oils to choose for cooking. Polysaturated oils (safflower,
corn) lower LDL, which is good, but also lower HDL. The worst
offenders are the saturated fats (meat fat, butter), which
raise LDL, lower HDL, and also include cholesterol itself.
(For more information, turn to chapter 15, “A
CommonSense Look at Diet and Health.”)
Diet is not the
only thing that affects your cholesterol level; other factors
include heredity, smoking, and hormones. Estrogen plays an
important role in keeping cholesterol levels down, and the
hormonal changes of menopause will adversely affect your LDL
and HDL counts.
Exercise and weight. Lack of exercise has been shown
to be a risk factor for heart disease. Regular aerobic
exercise seems to tone the heart muscle and help prevent
heart disease. Again, most of the studies about exercise and
heart disease have been done on men, but the effects are
thought to be similar in women. Strenuous athletics are not
necessary; moderate exercise such as brisk walking or
stair climbing are sufficient to benefit the
heart.
Exercise also
lowers cholesterol and blood pressure and is usually
associated with weight loss. Being overweight also
contributes to high cholesterol and high blood pressure, both
factors in developing heart disease.
Body shape is
another risk factor for heart disease. Women with
“apple-shaped” bodies—more weight around the
waistline—have a greater risk than
“pear-shaped” women who carry most of their weight
around their hips.
Women, especially
those who have already suffered heart disease and those with
high risk factors, should know that although the benefits of
exercise usually outweigh the risks, there is a slight chance
that strenuous exercise can contribute to heart attacks,
strokes, and arrhythmias. You should plan and discuss any
exercise program with your doctor, particularly if you have
not been physically active for a while.
Alcohol consumption. The effect of alcohol on heart
disease is a very controver-sial subject. On one hand, there
is plenty of documentation of the negative effects of
excessive drinking on not just the heart, but a number of
body systems. On the other, a number of tests in recent years
have indicated that moderate drinking (1 or 2 drinks a day)
may protect against heart disease.
The American Heart
Association has addressed this issue by advising that
drinking is safe only in moderation; and that if you don't
already drink, there really is no benefit to starting.
Social and psychological factors. It was once
speculated that as women entered the workforce in increasing
numbers and began experiencing the same workplace stresses as
men, heart attack rates in middle-aged women would begin to
approach those of their male counterparts. That has not
happened. Women working outside the home have about the same
rates of heart disease as women who don't. Twenty years of
research in the Framingham study found that employment itself
is not predictive of heart disease, but factors such as high
demands and low control of the situation, as well as
financial anxiety, are related to higher rates of heart
disease.
In men, heart
disease has been linked to the so-called “Type A”
personality, the impatient, driven, competitive personality
type. No similar link has been found in women. In fact,
Framingham data have shown that women who suppress anger and
hostility are more likely to suffer heart disease than those
who express it in the Type A manner. Having depression or
anxiety is also linked to increased rates of heart disease in
women.
Research over the
last 10 years has consistently found that heart disease
occurs more frequently in less educated women in lower
socioeconomic groups than in better educated women in higher
socioeconomic groups. The reasons for this are probably
related to a number of factors including poorer health care,
lack of health insurance, gender discrimination, and
increased stress.
Drugs
A number of
different drugs can also play an important role in preventing
heart disease.
Aspirin has received a lot of attention since several
studies found that, in small daily doses, it helps prevent
heart attacks. Unfortunately, the tests that turned up these
results were done only on men, and it is not known whether
the findings are applicable to women. Preliminary studies of
women's use of aspirin seems to suggest that a similar
protective factor may be found. Aspirin is thought to lower
heart attack risk because of its blood-thinning effects. But
more research is needed before aspirin's benefits for women
are fully defined.
Since some women
should not take aspirin because of other medical conditions
(for example, clotting disorders), and because dosing is
different for preventive therapy than it is for headaches or
other common uses, you should consult your physician before
taking aspirin to prevent heart disease.
Hormone replacement therapy has become one of the most
controversial areas of women's health. When you pass through
menopause, your body produces ever decreasing amounts of
estrogen. And since it is after menopause that heart disease
rates in women rise towards those in men, natural estrogen
depletion is thought to be a major factor. (Although not the
only one: Some scientists are testing the hypothesis that
iron loss during menstruation also helps protect against
heart disease.)
Many studies have
found that women on estrogen replacement therapy during and
after menopause have a lower risk of heart disease. However,
the subject is still controversial because replacing estrogen
also increases the risk of other diseases, particularly
endometrial cancer and possibly breast cancer. The therapy
has evolved over the years, and most women on hormone
replacement therapy now receive a combination of estrogen and
progestin, a hormone that prevents endometrial cancer.
However, not much is known about whether the addition of
progestin decreases estrogen's heart benefits, and a number
of studies are only now underway to test that effect.
The drugs used for
hormone replacement therapy are the same as those in oral
contraceptives, except at much lower doses; and combining
oral contraceptives and cigarette smoking compounds the risk
of heart disease. It's not known whether smoking has the same
effect during hormone replacement therapy. This is another
area that needs further investigation. For more on the
hormone replacement controversy, see chapter 31,
“Hormone Replacement Therapy: Weighing the Pros and
Cons.”
High blood pressure medications are available in great
variety if diet and behavior changes are not effective. There
are five major types:
-
Diuretics, which
reduce the amount of salt and fluid in the bloodstream, in
turn reducing blood pressure.
-
Beta blockers,
which reduce the force and speed of the heart's pumping
action.
-
ACE inhibitors,
which reduce the level of angiotensin, a chemical that the
body produces to raise blood pressure.
-
Calcium channel
blockers, which relax the arteries and reduce resistance to
bloodflow.
-
Vasodilators and
alpha adrenergic blocking agents, which also relax the
arteries.
Cholesterol lowering drugs work in several ways: They
prevent the body from producing cholesterol, reduce the
absorption of the cholesterol that you consume, or combine
with cholesterol to remove it from the bloodstream. Some of
the drugs that are used include niacin, lovastatin (Mevacor),
cholestryamine (Questran), gemfibrozil (Lopid), and probucol
(Lorelco).
Vitamin E, in early studies of women, has shown
promising effects on the heart. Taken for a sustained period
of time at high enough levels, it seems to lower the risk of
heart disease. However, researchers are unwilling to make a
firm recommendation until additional evidence is in.
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A lot of attention
is given to many of the “miracle” drugs offered by
modern science. Equally impressive are some of the diagnostic
tools that have been developed to detect heart disease, so
that it can be appropriately treated and controlled.
Diagnostic
procedures range from non invasive tests done outside
the body to invasive probes into the circulatory system.
Often, positive findings on non invasive tests like the
electrocardiogram or treadmill test signal the need for more
invasive procedures.
Electrocardiogram
The
electrocardiogram (known popularly as the ECG or EKG) is a
graphic representation of the electrical currents that run
through the heart as it pumps. The ECG can be taken while you
are resting or exercising (usually on a treadmill), and the
only discomfort you might experience is several small
electrodes attached to your skin.
Normal ECG readings
in women during exercise are likely to mean that no heart
disease is present; and—compared with men—abnormal
readings are much more likely to be false positives; that is,
not truly a sign of heart disease. One study found false
positives in only 8 percent of the men tested and a whopping
67 percent of women undergoing the same test. In other words,
even if stress testing is positive, there's still an
excellent chance that your heart is healthy. Some doctors
skip the stress test altogether, especially in a patient with
clear physical symptoms (such as repeated incidents of
angina), and move directly to more specific testing.
Radionuclide
Studies
These studies
follow radioactive substances that have been injected into
the bloodstream. One common example, exercise thallium
scintigraphy, uses computer imaging to track an injection of
radioactive thallium through the bloodstream and assess
bloodflow to the heart during exercise. This test also turns
up many false positives in women because breast tissue can
create a shadow that looks like a blockage. Another form of
radionuclide testing is used for women who are unable to
exercise strenuously enough for exercise testing. The drugs
used in these tests, dipyridamole (Persantine IV) or
adenosine (Adenocard), mimic the effects of
exercising.
Echocardiogram
Echocardiography is
a diagnostic method that measures ultrasound waves. The waves
are transmitted into the body, and the echoes that come back
from the heart's surface are transformed into a video picture
showing the size, shape, and movement of the heart. Like
radionuclide studies, echocardiography can be combined with
exercise or druginduced stress to study the heart and
blood flow under stress conditions. Dobutamine (Dobutrex) can
be administered during echocardiography to simulate the
effects of exercise on the heart. Doctors frequently use
echocardiography to confirm a suspicion of mitral valve
prolapse and other valvular disorders.
Angiogram
Angiography is a
way of seeing the interior of the heart and blood vessels. In
a procedure more invasive than electro or
echocardiography, a catheter (a long, flexible tube) is
inserted into a large blood vessel, usually the femoral
artery in the upper thigh, and threaded up to the heart in a
procedure called cardiac catheterization. Contrasting die is
injected through the catheter, allowing xrays of the
heart and blood vessels that can show the degree of
blockage.
The angiogram is
probably the most definitive tool for diagnosing heart
disease, but because it carries a small risk of injury or
death, it is not routinely prescribed. One of the
controversies about women's health care focuses on the
angiogram, which is ordered much less frequently for women
than for men. One study found that 10 times as many men as
women (40 percent, compared to 4 percent) were referred for
an angiogram after a positive ECG stress test. This is partly
because of the known high number of false positives in
women's stress ECGs, but it may also reflect a pervasive
pattern of less aggressive treatment of heart disease in
women. Many physicians treating women with heart disease
believe that this pattern is changing as the medical
profession and women themselves become more aware of the true
risk of serious heart disease.
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As with most other
diseases, there is a broad range of treatments available for
heart disease, proceeding from the minimum—lifestyle and
behavior changes—to the maximum—heart transplant.
Lifestyle changes to treat heart disease parallel those to
prevent it. A primary difference is that if you already have
heart disease, you should consult closely with your doctor as
you consider which changes will be most appropriate.
There are, of
course, many intermediate steps between simple lifestyle
changes and heart transplant. These include a variety of drug
therapies; angioplasty, in which arteries are widened with
the insertion of a balloon; and several different surgical
procedures including valve replacement and bypass
operations.
Heart disease is
really a variety of diseases that strike different parts of
the circulatory system and act in different ways. They are
progressive, interrelated conditions, and treatment of one
problem early in the continuum—for example, coronary
artery disease—can prevent more serious consequences
such as heart attack.
Obviously, there is
no single treatment. And there are no definitive solutions to
the problem of determining which therapies—most of which
have been tested primarily on men—will work best for
women. But understanding the available options is an
important first step in deciding, with your doctor, which
treatment is best for you.
Drugs
Drugs have been
used to treat heart disease for centuries. There's a wide
variety; and they work in a variety of ways. Little is known
about whether heart medications affect women differently than
men. But so far, indications are that the drug's effects are
similar, regardless of gender, although the most effective
dosage levels may vary.
Digitalis. Two hundred years ago a British physician
discovered that digitalis, an extract from the foxglove plant
commonly grown in English gardens, strengthens the
contraction of the heart muscle. This drug is still used to
treat congestive heart failure, and is also useful in
correcting irregular heartbeats.
Nitroglycerin. Nearly a century later, a Scottish
medical student theorized that amyl nitrite, known to relax
the capillaries, could relieve the pain of angina by
increasing blood flow to the heart. A form of that drug,
nitroglycerin, is still widely used for this purpose.
Beta blockers, often used to treat high blood
pressure, are among the most valuable drugs used to treat the
heart. They act to block the activity of the beta-adrenergic
system, a highly integrated nerve and hormonal system that
affects the heart's rhythm and strength of contractions,
among other things. Propranolol (Inderal), the first and most
widely used of the beta blockers, has been found effective
for treating angina, high blood pressure, and migraine
headaches. This, and related drugs, are also effective in
preventing second heart attacks.
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PUTTING THE PRESSURE ON PLAQUE
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For many people with clogged
coronary arteries, angioplasty now provides a less
traumatic alternative to traditional bypass surgery.
During this newer procedure, a balloon-tipped
catheter is threaded up through the circulatory
system until it reaches the diseased artery, then
inflated to squeeze back the encroaching plaque.
Often the balloon is surrounded by a collapsible mesh
tube called a stent. When the expanded stent has been
lodged firmly against the plaque, the balloon is
deflated and withdrawn.
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Calcium channel blockers were first approved to treat
irregular heartbeat, but were found to have other uses. The
flow of calcium across cell membranes in the heart muscle
plays a large role in determining how hard the heart
contracts: decreasing the flow of calcium across membranes
can improve heart function. These drugs—the most widely
used is verapamil (Isoptin, Calan)—also relieve the pain
of angina by relaxing the coronary arteries and helping the
heart beat more easily. Calcium supplementation (either
dietary or through pills) is not thought to effect the action
of calcium channel blockers.
Thrombolytics, known as clot-busters, are among the
wonder drugs of modern heart medications. Drugs such as
Tissue-Plasminogen Activator or tPA (Activase) and
streptokinase (Streptase) dissolve blood clots when injected
into the bloodstream. If administered shortly after a heart
attack, they can clear the obstruction before heart tissue is
deprived of oxygen and dies. Speed is critical for the
effectiveness of these drugs. New federal guidelines
recommend that most heart attack patients be given a
thrombolytic within 30 minutes of arrival at the emergency
room.
Some of the limited
existing data about women and thrombolytics indicate that
women are not as likely as men to get these drugs in the
emergency room, and when they do, the drugs do not work as
effectively. No one doubts, however, that these are important
drugs to use in treating both women and men.
Angioplasty
This procedure
involves attaching a tiny balloon to the tip of a catheter,
threading it up through an artery until it reaches a
developing blockage, then inflating the balloon to push the
blockage aside and enlarge the artery opening, or lumen. The
technical name for this procedure is percutaneous
transluminal coronary angioplasty or PTCA. It has a high
success rate, although blockage returns in many patients in
about 3 months. A refinement of angioplasty is a procedure
using a collapsible stent, a stainless steel tube that is
inserted and opened by inflating the balloon, then left in
place as a more permanent vessel opener when the balloon is
removed. Valvuloplasty, a procedure similar to angioplasty,
uses the balloon to open an obstructed portion of a heart
valve.
Women undergoing
angioplasty have lower success rates and higher complication
rates than men. This may be because women are usually sicker
and older when the procedure is performed, and because the
generally smaller surface area of the interior of their blood
vessels makes the treatment more delicate. Technological
advances in designing equipment specific to the needs of
women may help to eliminate these disparities.
Surgery
Women are referred
for heart surgery less frequently than men and they have
poorer outcomes, including a higher incidence of death.
Still, surgery can be very effective, although even when
successful, it is seldom the final “cure,” and many
heart patients continue to require some kind of daily
medication thereafter.
Coronary artery bypass graft (CABG), known popularly
as simply bypass surgery, is the most common form of heart
surgery. In bypass surgery, a clogged portion of a coronary
artery is replaced with a short piece of a blood vessel that
has been removed from another part of the patient's
body.
Women are probably
referred less than men because their outcomes are not as
good. This could be a blessing: Many think that CABG is
prescribed for men more often than it should be. Women are
sicker and older when they are referred for bypass surgery,
which may help explain the poorer outcomes. Once a woman
leaves the hospital following this surgery, however, her long
term survival rate is equal to a man's.
Valve replacement surgery is used when medications are
not effective in correcting the problems of damaged or
congenitally malformed heart valves. The natural valve is
replaced with an artificial one made of light metal or
plastic, or with a specially prepared valve taken from an
animal, most often a pig. Little is known about the different
outcomes in men and women who receive these
replacements.
Electrical Devices. Some people have an irregular
heartbeat that cannot be corrected with medications. If the
heartbeat is too slow, a surgically implanted pacemaker can
be an effective device to increase the heartbeat, and many
people live for years with one of these devices in place.
Often medications are still required after insertion of a
pacemaker. Another device, the implantable
cardioverterdefibrillator, automatically detects the
rapid or uncontrolled beats of ventricular tachycardia or
fibrillation when they occur and within seconds generates an
electrical shock to correct the problem.
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HOW BYPASS SURGERY GETS ITS NAME
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When a blockage occurs in one or
more of the coronary arteries supplying the heart
muscle with blood, the most effective solution is
often to establish a new route around the
barrier—to literally bypass the site of the
problem. To do this, surgeons generally snip out a
small portion of the saphenous vein in the leg and
graft it to the diseased coronary artery on either
side of the blockage. Short of an open heart
procedure or a transplant, this operation is about as
major as surgery gets.
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A heart transplant is the most dramatic of all
treatments. The procedure is used most frequently in patients
with severe cardiomyopathy (heart muscle disease). Heart
transplants are very rare, since they depend on the advanced
technological resources of a sophisticated medical center and
the availability of a compatible donor heart. However, with
advances in anti-rejection drugs, the operation is recognized
as an option that can prolong life by years in appropriately
selected patients. Because it is still so rare, little data
is available about the differences between men and women who
have received heart transplants
Cardiopulmonary
Resuscitation
CPR is an emergency
intervention for someone suffering cardiac arrest. Designed
to keep oxygenated blood flowing to the heart and brain until
the heartbeat resumes or life support is started, it is a
combination of chest compression and mouth-to-mouth
breathing. Only people properly trained in CPR should attempt
to administer it.
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As is the case with
many illnesses, heart disease in women can be complicated by
other factors. The two most important are diabetes and
pregnancy.
Diabetes
Diabetes most
commonly occurs after the age of 45. Depending on severity,
it is treated with oral medications that lower blood sugar
levels or with regular injections of insulin. More women than
men have diabetes, but this may simply be because there are
more women than men in the older age groups.
Ischemic heart
disease is the most common cause of death in diabetics, even
though diabetes itself is listed as one of the top-ten causes
of death in this country. At any given age, a woman with
diabetes has more than twice the risk of having a heart
attack than a woman without diabetes. The increased risk of
heart disease in diabetics is also greater in women than in
men. Diabetics are also more likely to be overweight, have
high cholesterol, and suffer from hypertension, all of which
are also risk factors for heart disease.
Pregnancy
Because coronary
artery disease usually strikes later in life, it is rarely a
complication during pregnancy. However, a number of heart
problems, such as congenital defects and valvular disease, do
occur in women of childbearing age. Most of these diseases
can be well-managed in pregnancy and present little danger to
mother or baby. There is even a report of a woman who had a
baby four years after having had a heart transplant.
Some symptoms of
pregnancy are very similar to symptoms of heart disease; for
example, fatigue, shortness of breath, swelling in the arms
and legs, and sometimes palpitations. If you are pregnant,
and concerned about such symptoms, discuss them with your
doctor; usually there is little cause for alarm. Similarly,
heart murmurs are commonly heard during pregnancy, but
usually just indicate increased blood flow across the aortic
and pulmonary valves, rather than a valve abnormality. Your
blood pressure should be monitored regularly during
pregnancy, because it often rises.
Most diagnostic
techniques for heart disease can be used during pregnancy,
but those requiring radioactive substances should normally be
avoided because of possible harm to the developing baby.
(Radioactive substances are sometimes used during pregnancy
when the need for diagnosis in the mother outweighs the risk
to the baby.) Echocardiography is not harmful to the child,
and is used for diagnosis in a pregnant heart patient
whenever needed.
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