Arteriosclerosis is the general term for vascular disease in which arteriesharden (become thickened), making the passage of blood difficult and some-times impossible. Atherosclerosis is the form of arteriosclerosis that most frequently occurs in developed countries. It is believed to begin in childhood and is considered one of the major causes of heart attack.
Atherosclerosis affects the inner lining of arteries (the intima), where deposits of cholesterol, fats, and other substances accumulate over time, thickening and weakening artery walls. These deposits are called plaque (Figure 18-1). Plaque deposits gradually reduce the size of the lumen of the artery and, consequently, the amount of blood flow. The reduced blood flow causes an inadequate supply of nutrients and oxygen delivery to and waste removal from the tissues. This condition is called ischemia.
The reduced oxygen supply causes pain. When the pain occurs in the chest and radiates down the left arm, it is called angina pectoris and should be consid-ered a warning. When the lumen narrows so that a blood clot (thrombus) occurs in a coronary artery and blood flow is cut off, a heart attack occurs. The dead tissue that results is called an infarct. The heart muscle that should have received the blood is the myocardium.
Thus, such an attack is commonly called an acute myocardial infarction (MI). Some clients who experience an MI will require surgery to bypass the clogged artery. The procedure is a coronary artery bypass graft (CABG), which is commonly referred to as bypass surgery.
When blood flow to the brain is blocked in this way or blood vessels burst and blood flows into the brain, a stroke, or cerebrovascular accident(CVA), results. When it occurs in tissue some distance from the heart, it iscalled peripheral vascular disease (PVD).
Hyperlipidemia, hypertension (high blood pressure), and smoking are majorrisk factors for the development of atherosclerosis. Other contributory factors are believed to include obesity, diabetes mellitus, male sex, heredity, personality type (ability to handle stress), age (risk increases with years), and sedentary lifestyle. Although some of these factors are beyond one’s control, some factors are not.
It is known that dietary cholesterol and triglycerides (fats in foods and in adipose tissue) contribute to hyperlipidemia. Foods containing saturated fats and trans fats increase serum cholesterol, whereas unsaturated fats tend to reduce it.
Lipoproteins carry cholesterol and fats in the blood to body tissues. Low-density lipoprotein (LDL) carries most of the cholesterol to the cells, and elevated blood levels of LDL are believed to contribute to atherosclerosis. High-density lipoprotein (HDL) carries cholesterol from the tissues to the liver for eventual excretion. It is believed that low serum levels of HDL can contribute to atherosclerosis.
Diet can alleviate hypertension, reduce obesity, and help control diabetes mellitus. A sedentary lifestyle can be changed. Exercise can help the client lose weight, lower blood pressure, and increase the HDL (“good”) cholesterol level. Exercise must be done in consultation with the physi-cian and be increased gradually. Also, one can stop smoking. In sum, a person can considerably reduce the risk of atherosclerosis and thus an MI, CVA, and PVD.