Critical Care Nursing Theory
Atherosclerosis
Atherosclerosis
-Atherosclerosis is a major cause of cardiovascular disease.
Pathophysiological Principles
-It begins when the inner, protective layer of the artery(endothelium) is
damaged.
Three known causes of the damage include
1- Elevated levels of cholesterol and triglycerides in the blood,
2- Hypertension,
3- Cigarette smoking.
- Gradually, as fatty substances, cholesterol, cellular waste products,
calcium, and fibrin pass through the vessel, they are deposited in the inner
lining of an artery.
- As a result of the deposition of these materials, a lipid plaque with a
fibrous covering, also known as an atheroma, builds up, and blood flow in
the artery becomes partially or completely blocked.
- The injury to the vessel and the resulting accumulation of these substances
in the inner lining of the artery cause white blood cells, smooth muscle
cells, and platelets to aggregate at the site.
- As a result, a matrix of collagen and elastic fibers form, and the
endothelium becomes much thicker.
- The core of the fibrous plaque can become necrotic, and hemorrhage and
calcification may result.
- A thrombosis may also occur, thus contributing even more to the blockage
of the vessel lumen .
- These fibrous plaques are most often found in the coronary, popliteal, and
internal carotid arteries and in the abdominal aorta.
Dr. Abdul-Monim Batiha Assistant Professor Of Critical Care Nursing
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Critical Care Nursing Theory
Atherosclerosis
- Because of the fibrous plaque, the amount of blood flow through the artery
is reduced, resulting in decreased supply of oxygen to tissues.
- Symptoms often do not occur, however, until 75% or more of the blood
supply to the area is occluded.
Risk Factors
- Risk factors for the development of atherosclerosis are usually classified
into two groups: major risk factors and contributing risk factors. Major risk
factors increase significantly the risk of cardiovascular disease. Major risk
factors are further divided into those that are uncontrollable and those that
can be lowered by modification, treatment, or control.
Major Uncontrollable Risk Factors
1- Age
- There is an increased incidence of all types of atherosclerotic disease with
aging.At older ages, women who have an MI are more likely than men to
die from it within a few weeks.
2- Heredity
- The tendency to develop atherosclerosis seems to run in families, although
the risk is presumed to be a combination of environmental and genetic
influences.
3- Sex
- Men have a greater risk for development of coronary artery disease than
woman, and men have MIs at a younger age. After menopause, however,
women’s death rate from coronary disease rises, but it never reaches the
risk levelof men.
Dr. Abdul-Monim Batiha Assistant Professor Of Critical Care Nursing
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Critical Care Nursing Theory
Atherosclerosis
Major risk factors that can be Modified, treated, or
controlled
1- Cigarette Smoking
- A smoker’s risk of an MI is double that of a nonsmoker. Smoking is the
biggest risk factor for sudden cardiac death. A smoker’s risk of sudden
death is two to four times greater than the nonsmoker’s risk. Smokers are
more likely to die from the infarction and to die within 1 hour than
nonsmokers. Exposure to environmental smoke also increases the risk of
heart disease for nonsmokers.
2- High Blood Cholesterol
- High cholesterol levels increase the risk of coronary artery disease.
Most cholesterol in the blood is carried in low-density lipoprotein (LDL),
often called “bad” cholesterol. This type of cholesterol is deposited in the
artery walls, and high blood levels of LDL increase the risk of coronary
heart disease. An LDL level of less than 100 mg/dL is optimal. Highdensity cholesterol (HDL) removes cholesterol from tissues and transports
the excess cholesterol back to the liver, where it is metabolized. For this
reason, HDL is often called “good” cholesterol. A low level of HDL (<40
mg/dL) is associated with a higher risk of coronary artery disease.
3- Hypertension
- Hypertension is a major risk factor that is termed the silent killer because it
has no specific symptoms and no early warning signs. Men have a greater
risk for hypertension than women until the age of 55 years. Between 55 and
75 years, the risk for development of hypertension is about the same for
men and women. After the age of 75 years, hypertension is more likely to
develop in women than in men.
Physical Inactivity
- A lack of physical activity plays a significant role in the development of
heart disease. When lack of regular exercise is combined with overeating
and obesity, high cholesterol can result and further increase the risk of heart
disease.
Dr. Abdul-Monim Batiha Assistant Professor Of Critical Care Nursing
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Critical Care Nursing Theory
Atherosclerosis
4- Obesity and Overweight
- Obesity and excess weight are associated with an increased mortality rate
from coronary artery disease and stroke. Excess weight is also linked with
an increased incidence of hypertension, insulin resistance, diabetes, and
dyslipidemia. Central obesity (intra-abdominal fat) appears to be a stronger
predictor of cardiovascular disease than peripheral or subcutaneous obesity.
A higher risk for cardiovascular disease is found for women with a
waist greater than 35 inches and for men with a waist greater than 40
inches.
5- Diabetes Mellitus
- Diabetes mellitus is associated with a marked increased risk of
cardiovascular disease. This increased risk occurs even if the person
maintains control of blood glucose levels. About two thirds of people with
diabetes die of some form of heart or blood vessel disease.
Contributing Risk Factors
1- Stress
- A person’s response to stress may be a contributing factor to
cardiovascular disease.
- The behaviors that a person engages in when under stress (such as
smoking, overeating) may contribute to the risk of cardiovascular disease.
2- Sex Hormones
- Men have a higher incidence of MI than women who are premenopausal.
- However, the loss of estrogen as women age is believed to be a
contributing factor to the marked rise in women’s risk of heart disease after
menopause.
- Female hormones are also know to raise high density lipoprotein (HDL)
and to lower total blood cholesterol levels, whereas male hormones have
the opposite effect.
Dr. Abdul-Monim Batiha Assistant Professor Of Critical Care Nursing
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Critical Care Nursing Theory
Atherosclerosis
3- Birth Control Pills
- Low-dose oral contraceptives are associated with a lower risk for
development of heart disease than are the earlier, higher-dose forms of
birth control pills.
- However, for a woman who takes the low-dose form, the risk of heart
disease increases if she also smokes or has hypertension.
4- Excessive Alcohol Intake
- The excessive intake of alcohol has been associated with hypertension,
heart failure, stroke, high triglycerides, and dysrhythmias.
5- Homocysteine Levels
- Homocysteine is a sulfur-containing amino acid that is synthesized during
protein catabolism.
- It depends on vitamin B6, folate, and vitamin B12 to be metabolized.
- Homocysteine aids in the growth and maintenance of tissue and plays a
role in the prevention of skin and nail disorders.
- Hyperhomocysteinemia can be genetic (rare) or acquired. The acquired
form occurs in about 5% to 7% of the population.
- An association has been shown between elevated levels of homocysteine
and cardiovascular disease.
- Homocysteine causes increased platelet adhesiveness, enhances LDL
deposition in the arterial wall, and activates the coagulation cascade.
Dr. Abdul-Monim Batiha Assistant Professor Of Critical Care Nursing
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