732
P A R T 8
Drugs acting on the cardiovascular system
all of the small intestine. The chylomicrons pass through
the wall of the small intestine, are picked up by the sur-
rounding intestinal lymphatic system, travel through the
system to the heart, and are then sent out into circula-
tion. The proteins that are exposed on the chylomicron,
called apoproteins, determine the fate of the lipids or
fats being carried. For example, some of these packages
are broken down in the tissues to be used for energy,
some are stored in fat deposits for future use as energy
and some continue to the liver, where they are further
processed into lipoproteins.
Lipoproteins
The lipoproteins produced in the liver that have well-
known clinical implications are the
low-density
lipoproteins (LDLs)
and the
high-density lipoproteins
(HDLs)
.
LDLs enter circulation as tightly packed choles-
terol, triglycerides and lipids—all of which are carried
by proteins that enter circulation to be broken down for
energy or stored for future use as energy. When an LDL
package is broken down, many remnants or leftovers
need to be returned to the liver for recycling. If a person
has many of these remnants in the blood vessels, it is
thought that the inflammatory process is initiated to
help remove this debris. Some experts believe that this is
the underlying process involved in atherogenesis.
HDLs enter circulation as loosely packed lipids that
are used for energy and to pick up remnants of fats
and cholesterol that are left in the periphery by LDL
breakdown. HDLs serve a protective role in cleaning
up remnants in blood vessels. It is known that HDL
levels increase during exercise, which could explain why
people who exercise regularly lower their risk of CAD.
HDL levels also increase in response to oestrogen, which
could explain some of the protective effect of oestrogen
before menopause.
Cholesterol
The body needs fats, particularly cholesterol, to main
tain normal function. Cholesterol is the base unit for the
formation of the steroid hormones (the sex hormones, as
well as the adrenal cortical hormones). It is also a basic
Women and heart disease
Until the late 1990s, heart disease was considered to be
a condition that primarily affected men. Because of that
belief, women were seldom screened for heart disease,
and when they did experience acute cardiac events, they
were not treated promptly or adequately. However, recent
research has shown that heart disease is the leading cause
of death among women, surpassing such diseases as
breast and colon cancers.This finding has led to further
research, still ongoing, about women and heart disease.
Women enjoy a protective hormone effect against
the development of coronary artery disease (CAD) until
menopause, when oestrogen loss seems to rapidly increase
the production of atheromas and the development of
CAD. In several studies, women who received hormone
replacement therapy (HRT) at menopause had a significantly
reduced risk of CAD and myocardial infarction (MI) in the
first few years after the onset of menopause. Research
showed, however, that after 5 years of HRT the incidence of
MI and stroke rose sharply, leading to an early closure of the
study. Studies have found that women experience different
symptoms of heart disease—jaw and neck pain, fatigue and
insomnia—and sometimes these are overlooked.
HRT is not recommended as a means of reducing
the risk of heart disease or stroke, although it is still
recommended for the treatment of severe menopausal
symptoms in the first few years after menopause. Women
should be advised to reduce other cardiac risk factors by
eating a diet low in saturated fats, exercising regularly, not
smoking, controlling weight, managing stress, and seeking
treatment for gout, hypertension and diabetes.
Clearly, heart disease is not just a disease of men.
Research will continue to offer healthcare professionals
new information on preventing and treating heart disease
in women.
Gender considerations
BOX 47.3
■■
TABLE 47.2 Risk factors for coronary artery disease
Unmodifiable risks
Modifiable risks
Suggested modifications
Family history
Sedentary lifestyle
Exercise
Age
High-fat diet
Low-fat diet (polyunsaturated and monounsaturated fats)
Gender
Smoking
Smoking cessation
Obesity
Weight loss
High stress levels
Stress management
Bacterial infections
Antibiotic treatment
Diabetes
Control of blood glucose levels
Hypertension
Control of blood pressure
Gout
Control of uric acid levels
Menopause
Hormone replacement therapy (first few years of menopause only)
