340 Coronary Heart Disease and Hypertension
CORONARY HEART DISEASE
Coronary heart disease, also called coronary artery or is-
chemic heart disease, is a condition that develops when the
coronary arteries supplying blood to the cardiac, or myocar-
dial, tissue become narrowed with fatty plaque deposits, a
process called atherosclerosis. Myocardial ischemia, an inad-
equate supply of blood to the cardiac tissue, results from this
coronary artery narrowing and many times is accompanied
by chest pain called angina pectoris. Myocardial infarction
(death of cardiac tissue), commonly called a heart attack, oc-
curs when the supply of blood ”ow is stopped due to a com-
plete blockage of the artery from unstable plaque or ischemia
that is severe or prolonged. With ischemia and/or infarction,
the electrical system of the heart is predisposed to distur-
bances that can develop into irregular cardiac rhythms, called
arrhythmias. Many of these arrhythmias are life-threatening
and can cause sudden cardiac death.
Risk Factors for CHD
Coronary heart disease results from many interacting causal
factors. Studies, like the Framingham Heart Study (Wilson
et al., 1998) show the major risk factors for CHD are additive
in predictive power. The risk of an individual can be deter-
mined by totaling the risk imparted by each of the major risk
factors. Many of these risk factors overlap making CHD a
multifactorial disease. The most widely accepted risk factors
include high blood pressure, cigarette smoking, increasing
age, gender issues, family history, diabetes mellitus, seden-
tary lifestyle, obesity, stress, personality, and abnormal cho-
lesterol levels.
Certain risk factors are nonmodi“able. These include age,
gender, and family history. With aging, risk of developing
CHD increases. Nearly half of all coronary victims are over
the age of 65. Women develop heart disease at a later age,
generally 10 years after men. This is thought to be due to
the cardioprotective nature of estrogen before menopause
(Saliba, 2000). A positive family history of CHD poses a
signi“cant risk factor for the development of heart disease in-
dependent of other risk factors. Studies have shown that a
family history of CHD particularly creates risk for females
and for early onset heart disease (Dzau, 1994; Pohjola-
Sintonen, Rissaness, Liskola, & Luomanmaki, 1998). Indi-
viduals with various nonmodi“able risk factors such as
family history can still decrease their risk by altering other
risk factors that are modi“able.
Cigarette smoking, obesity, sedentary lifestyle, high blood
pressure, diabetes, and elevated cholesterol levels can be
modi“ed„or at least controlled„through medication or be-
havioral changes, thereby decreasing CHD risk. For exam-
ple, the Nurse•s Health Study (Stampfer, Hu, Manson, Rimm,
& Willett, 2000) showed that those individuals who smoked
greater than 15 cigarettes a day were at the greatest risk for
the development of CHD but, even those who smoked 1 to 14
cigarettes a day tripled their risk over those who did not
smoke. There is a direct dose-response relationship of CHD
and smoking and a large number of case-controlled and ob-
servational studies demonstrate that cigarette smoking dou-
bles the incidence of CHD and increases mortality by 70%
(Hennekens, 1998). Although high cholesterol level can be
inherited, it is also to some extent related to diet and can be
modi“ed. There are several components to blood cholesterol
that can be measured including elevated total cholesterol
level, elevated low-density lipoprotein cholesterol (LDL),
and low high-density lipoprotein (HDL) (Grundy, Pasternak,
Greenland, Smith, & Fuster, 1999). Evidence suggests that
the ratio of total cholesterol to HDL cholesterol provides the
best measure of CHD risk (NCEP, 1993), and a 1% decrease
in total cholesterol level is shown to produce a 2% to 3% de-
creased risk of CHD (La Rosa et al., 1990). Hypertension,
diabetes mellitus, and obesity are also often genetically in”u-
enced but, like cholesterol levels, can be controlled with
lifestyle changes and/or medication. Studies including the
Nurse•s Health Study (Hu et al., 1997) and the Framingham
Heart Study (Wilson, 1994) show a two to threefold risk of
CHD in the obese over a healthy weight population. Obesity
and lack of physical activity worsen other factors including
hypertension, high cholesterol, and diabetes (Hennekens,
1998).
Despite the aforementioned evidence, controversy re-
mains regarding the importance of some of the standard risk
factors and the role diet and exercise play in the development
of coronary disease. Additionally, there are new “ndings
suggesting that additional risk factors may be important. For
example, an increased risk of CHD has been associated with
elevated plasma homocysteine levels (Malinow, Bostrum, &
Krauss, 1999). The most widely accepted CHD risk factors
continue to be smoking, cholesterol levels, and high blood
pressure.Psychosocial Risk FactorsThere is increasing recognition that, in addition to so-called
standard CHD risk factors, additional variables in the behav-
ioral and psychosocial domain may also contribute to the de-
velopment and progression of coronary heart disease and are
important to consider in efforts at treatment. These variables