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Cardiovascular disease is a collective term used to refer to disorders of the circulatory system (heart, arteries, veins) of the body. Cardiovascular disease affects approximately 82 million Americans at an annual direct cost of about $167 billion (in 2007). Direct costs are personal health care expenditures for hospital and professional services care; prescribed medications; and home care as reported by the Medical Expenditure Panel Survey of the Agency for Healthcare Research and Quality, by diagnosis, excluding nursing home care costs and costs associated with comorbidities (National Heart, Lung, and Blood Institute, 2007).

These diseases have been subdivided into the areas or organs of the body in which the pathology is most obvious, such as coronary artery disease (CAD) (see Chapter 22), to narrowing or obstruction of the arteries of the heart and leading to angina pectoris (see Chapter 25), and myocardial infarction (MI). Stroke (see Chapter 27) refers to either an obstruction (ischemic stroke) or rupture (hemorrhagic stroke) of blood vessels in the brain. An increase in the pressure with which blood circulates through the arteries and veins is referred to as hypertension (see Chapter 23). Dysrhythmias (see Chapter 24) are abnormalities in the electrical conduction pathways of the heart that lead to inefficient pumping of blood through the circulatory system. Peripheral vascular disease involves disorders of the blood vessels of the arms and legs. It can be subdivided into two types, depending on whether it is arterial or venous in origin: peripheral arterial disease (see Chapter 26), such as obstructive arterial disease, or venous disorders, such as acute deep vein thrombosis (see Chapter 27). The long-term pathology of any one or a combination of these diseases affecting the circulatory system leads to heart failure (see Chapter 28) and eventual death.

There are many causative factors that lead to cardiovascular disorders (Box 21-1). Lifestyle is recognized as possibly the greatest contributor to a variety of diseases that reduce the quality of life and end lives prematurely. These diseases also cost the American economy billions of dollars that could be used in many more positive, beneficial ways. Since the 1920s, investigators have hypothesized about various factors that lead to cardiovascular disease. Research during the 1960s indicated that persons with hypertension, diabetes mellitus, dyslipidemia, and obesity—alone or in combination—were at greater risk for progressive cardiovascular disease.

Table 21-1 gives the definition of metabolic syndrome provided in a consensus statement from the International Diabetes Federation; the National Heart, Lung, and Blood Institute; the American Heart Association; the World Heart Federation; the International Atherosclerosis Society; and the International Association for the Study of Obesity. People with central obesity and two of the four other criteria are defined as having metabolic syndrome.

Table 21-1

Definitions and Characteristics of Metabolic Syndrome*

	NATIONAL CHOLESTEROL EDUCATION PROGRAM (UNITED STATES)
RISK FACTOR DEFINING LIMIT	MEN	WOMEN
Waist circumference (inches)‡	>40	>35
High-density lipoprotein cholesterol (mg/dL)	<40	<50
Triglycerides (mg/dL)	>150	>150
Blood pressure (mm Hg)¶	>130/85	>130/85
Fasting glucose (mg/dL)**	>100	>100

^*People with central obesity and at least two of the remaining four factors are considered to have metabolic syndrome.

^‡There are specific circumferences for different ethnicities in the citation accompanying the table.

This also applies to those with previously diagnosed type 2 diabetes.

^¶All part of Alberti reference.

^**All part of Alberti reference.

Data from Alberti KG, Eckel RH, Grundy SM, et al: International Diabetes Federation Task Force on Epidemiology and Prevention; National Heart, Lung, and Blood Institute; American Heart Association; World Heart Federation; International Atherosclerosis Society; International Association for the Study of Obesity: Harmonizing the metabolic syndrome: a joint interim statement of the International Diabetes Federation Task Force on Epidemiology and Prevention; National Heart, Lung, and Blood Institute; American Heart Association; World Heart Federation; International Atherosclerosis Society; and International Association for the Study of Obesity, Circulation 120:1640-1645, 2009.