Presentation Package

1
chapter
20
Cardiovascular Disease and Physical Activity
2
Learning Objectives

• Find out the major causes of death in the United
  States and how a lack of physical activity
  contributes to these conditions
• Understand the concept of risk factors and be
  able to identify the major risk factors for
  coronary artery disease (CAD) and hypertension
• Learn how atherosclerosis, hypertension, and CAD
  develop

(continued)
3
Learning Objectives (continued)

• Discover what specific physiological alterations
  resulting from exercise training reduce the risk
  of death from CAD, hypertension, and other
  cardiovascular diseases
• Learn what blood pressure changes result from
  endurance exercise training in moderately
  hypertensive individuals
• Find out if there is any risk of death with
  endurance exercise training

4
The Leading Causes of Deathin the United States
in 2003

• Data from American Heart Association, 2006.

5
Prevalence of Cardiovascular Disease

• In 2003
• gt1.2 million heart attacks
• 480,000 deaths due to heart attacks
• 1 in 5 deaths was attributable to CAD
• 1 in 2.7 deaths was attributable to
  cardiovascular diseases
• 467,000 coronary artery bypass surgeries
• 1,244,000 angioplasties
• Over 2,000 heart transplants

6
Factors Contributingto Decline in Deaths

• Improved public awareness (e.g., concept of risk
  factors)
• Increased use of preventive measures, including
  lifestyle changes
• Better and earlier diagnosis
• Improved drugs for specific treatment
• Better emergency and medical care

7
Cardiovascular Diseases

• Coronary artery disease (CAD)
• Hypertension
• Stroke
• Heart failure
• Peripheral vascular disease
• Valvular, rheumatic, and congenital heart disease

8
The Leading Causes of DeathFrom Cardiovascular
Disease

• Data from American Heart Association, 2006.

9
Coronary Artery Disease

• Coronary artery disease (CAD) involves
  atherosclerosis in the coronary arteries
• Atherosclerosis progressive narrowing of the
  arteries due to plaque formation
• Ischemia a deficiency of blood flow to the heart
  caused by CAD
• Angina pectoris chest pain
• Myocardial infarction a heart attack due to
  ischemia leading to irreversible damage and
  necrosis

10
Atherosclerosis

• Not a disease of the aged
• Pathological changes in the blood vessels begin
  in infancy and progress during childhood
• Rate of progression is determined by genetics and
  lifestyle factors (smoking, diet, physical
  activity, and stress)

11
Progressive Formation of Plaquein a Coronary
Artery
12
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13
Hypertension

• In children blood pressures above the 90th or
  the 95th percentile
• About one in every three adult Americans has
  hypertension
• Causes the heart to work harder
• Strains the systemic arteries and arterioles
• Can cause pathological hypertrophy of the heart
• Can lead to atherosclerosis, heart attacks, heart
  failure, stroke, and renal failure

14
Stroke

• Cardiovascular disease that affects the cerebral
  arteries
• Ischemic stroke
• Cerebral thrombosis a blood clot forms in a
  cerebral vessel, most often at the site of
  atherosclerotic damage
• Cerebral embolism an undissolved mass of
  material breaks loose from another site in the
  body and lodges in a cerebral artery
• Hemorrhagic stroke
• Cerebral hemorrhage rupture of one of the
  cerebral arteries
• Subarachnoid hemorrhage surface vessel on the
  brain ruptures, bleeding into the space between
  the brain and the skull

15
Congestive Heart Failure

• Heart muscle becomes too weak and cannot maintain
  adequate cardiac output
• It can result from damage to heart from
  hypertension, atherosclerosis, valvular heart
  disease, viral infections, and heart attack
• Blood backs up in veins, causing systemic and
  pulmonary edema
• Can progress to irreversible damage, requiring a
  heart transplant

16
Other Cardiovascular Diseases

• Peripheral vascular disease
• Arteriosclerosis
• Valvular heart disease
• Rheumatic heart disease
• Congenital heart disease

17
The Three Layers of an Artery Wall
18
Pathophysiology of CAD

• Early theory
• Local injury induces dysfunction of the
  endothelium
• Blood platelets and monocytes adhere to the
  exposed connective tissue
• Platelets release platelet-derived growth factor
  that promotes smooth muscle cell migration from
  the media to the intima
• Plaque forms at the site of injury
• Lipids are attracted to the plaque

19
Changes in the Arterial Wall With Injury
20
Pathophysiology of CAD

• Newer theory
• Monocytes attach themselves to endothelial cells
• Monocytes differentiate into macrophages and
  ingest oxidized LDL-C, becoming enlarged foam
  cells to form fatty streaks
• Smooth muscle cells accumulate under the foam
  cells
• Endothelial cells slough off, exposing underlying
  connective tissue
• Platelets attach to exposed tissue

21
Illustration of Fissure or Rupture of an Unstable
Plaque in a Coronary Artery
22
Plaque Composition

• Composition of the plaque and its fibrous cap is
  critical
• Small plaques (where there is typically less than
  50 occlusion of the artery) that have thin
  fibrous caps and are heavily infiltrated with
  foam cells are the most dangerous

23
Pathophysiology of Hypertension

• More than 90 of people with hypertension have
  essential hypertension
• Risk factors
• Heredity, including race
• Increasing age and male sex
• Sodium sensitivity
• Excessive alcohol consumption and use of tobacco
  products
• Obesity and overweight
• Diabetes or insulin resistance
• Physical inactivity
• Oral contraceptives
• Pregnancy
• Stress

24
Primary Risk Factors for CAD

• Tobacco smoking
• Hypertension
• Abnormal blood lipids and lipoproteins
• Physical inactivity
• Obesity and overweight
• Diabetes and insulin resistance

25
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26
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27
Proposed CAD Markers

• C-reactive protein (CRP) produced in the liver
  and smooth muscle cells within coronary arteries
  in response to injury or infection
• Fibrinogen blood protein integral in the process
  of blood clotting
• Homocysteine amino acid used to make protein
• Lipoprotein(a) similar to LDL-C may reduce the
  ability to dissolve blood clots

28
Lipoproteins

• Lipoproteins proteins that carry blood lipids
• Low-density lipoproteins (LDL-C)
• High-density lipoproteins (HDL-C)
• Very low-density lipoproteins (VLDL-C)
• Ratio of total cholesterol to HDL-C is possibly
  the most accurate lipid index of risk for CAD
• gt5.0 increased risk
• lt3.0 low risk

29
Controllable Risk Factorsfor Hypertension

• Insulin resistance
• Obesity and overweight
• Diet (sodium, alcohol)
• Use of oral contraceptives
• Use of tobacco products
• Stress
• Physical inactivity

30
Metabolic Syndrome

• Hypertension, coronary artery disease, obesity,
  and diabetes are linked through the common
  pathway of insulin resistance
• Metabolic syndrome, syndrome x, and insulin
  resistance syndrome are terms used to describe
  this interrelationship
• Obesity and/or insulin resistance could be the
  trigger that starts metabolic syndrome

31
Percentages of the U.S. Population at Increased
Risk for Coronary Artery Disease Based on Primary
Risk Factors

• Reproduced from Caspersen, C.J. Physical
  activity and coronary heart disease. Physicians
  Sportsmedicine 1987 15(11) 43-44.

32
Reducing Risk Through Physical Activity

• Epidemiological evidence
• Physiological adaptations with training that
  might reduce risk
• Risk factor reduction with exercise training

33
Epidemiological Evidence

• Physical inactivity doubles the risk of CAD
• Low-intensity physical activity is sufficient to
  reduce the risk of this disease
• Health benefits do not require high-intensity
  exercise
• More vigorous exercise likely provides even
  greater benefits

34
Physical Activity vs. Physical FitnessDoseRespon
se Curve
Reprinted, by permission, from P.T. Williams,
2001, "Physical fitness and activity as separate
heart disease risk factors A metaanalysis,"
Medicine and Science in Sports and Exercise 33
754-761.
35
Aerobic Training Adaptations

• Produce larger coronary arteries which increases
  the capacity for blood flow to the heart
• Increased cardiac pumping capacity
• Improved collateral circulation in the heart
• Improved endothelial function
• Reduce blood pressure (7 mmHg) in individuals
  with mild to moderate hypertension
• Improves cholesterol ratio
• Weight reduction
• Improves insulin sensitivity
• Stress management

36
Comparison of the Left Main Coronary Artery in
(a) Sedentary and (b) Exercising Monkeys on
Atherogenic Diets
37
Reducing the Risk of Hypertension Through Exercise

• People who are active and those who are fit have
  reduced risk for developing hypertension
• Increased plasma volume that accompanies physical
  training does not increase blood pressure due to
  training-induced increased capillarization and
  increased venous capacity
• Resting blood pressure decreases by training in
  people with hypertension

38
Risk of Heart Attack and Death During Exercise

• Deaths during exercise are rare, although
  typically highly publicized
• Deaths during exercise in people over 35 usually
  are caused by a cardiac arrhythmia resulting from
  atherosclerosis
• Deaths during exercise in people under age 35 are
  usually caused by hypertrophic cardiomyopathy,
  congenital coronary artery abnormalities, aortic
  aneurysm, or myocarditis

39
Risk of Primary Cardiac Arrest During Vigorous
Exercise and at Other Times Throughout a 24 h
Period

• Data from D.S. Siscovick et al., 1984, "The
  incidence of primary cardiac arrest during
  vigorous exercise," New England Journal of
  Medicine 311 874-877.