Transcript Slide 1

Cardiovascular Disease
and Physical Activity
CHAPTER 21 Overview
• Forms of cardiovascular disease
• Understanding disease process
• Determining individual risk
• Reducing risk through physical activity
• Risk of heart attack and death during exercise
• Exercise training and rehabilitating patients with
heart disease
Introduction to
Cardiovascular Disease
• Cardiovascular disease leading cause of
serious illness and death in United States
• Affects over 80 million Americans
• Accounts for 1/3 of all US deaths annually
• Over $500 billion in annual costs
Figure 21.1
Introduction to
Cardiovascular Disease
• In 2006 alone, in the United States
– 448,000 bypass surgeries
– 1,313,000 coronary angioplasties
– 2,200 heart transplants
• Death rate steadily declining since 1960s
– Improved public awareness and lifestyle changes
– Better and earlier diagnosis
– Better treatment options
• A major health concern worldwide
Table 21.1
Forms of Cardiovascular Disease
• Coronary heart disease (CHD)
• Hypertension
• Stroke
• Heart failure
• Other (peripheral, valvular, congenital)
Forms of Cardiovascular Disease:
Coronary Heart Disease
• Accounts for half of cardiovascular deaths
• Progressive narrowing of coronary arteries
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Fatty plaque formation
Atherosclerosis
Blood supply to myocardium compromised
Myocardial ischemia  angina pectoris
• Leads to myocardial infarction (MI)
– Heart attack
– Irreversible heart muscle cell death due to lack of O2
Figure 21.2
Figure 21.3
Forms of Cardiovascular Disease:
Coronary Heart Disease
• Atherosclerosis begins early in life
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Fatty streaks appear in infancy, childhood
Fatty streaks appear in coronary arteries in teens
Fibrous plaques develop in 20s
Combination of genetics and lifestyle
Forms of Cardiovascular Disease:
Hypertension
• High blood pressure
– Systolic ≥140 mmHg, diastolic ≥90 mmHg
– Affects 32% of US adult population
• Heart must work harder to eject blood
• Places greater strain on arteries
• Causes enlarged heart, scarred/stiff arteries
• Eventually leads to atherosclerosis, MI, etc.
Forms of Cardiovascular Disease:
Hypertension
• Prehypertension
– Systolic 120 to 139 mmHg
– Diastolic 80 to 89 mmHg
– Affects 28% of US adult population
• More common in black Americans
– 1.8 times greater rate of fatal stroke
– 1.5 times greater rate of heart disease death
– 4.2 times greater rate of kidney disease
Table 21.2
Forms of Cardiovascular Disease:
Stroke
• Affects cerebral arteries
– Restricts brain blood flow
– 795,000 strokes in United States annually
• Ischemic stroke
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Most common type
Obstructed cerebral artery limits O2 delivery
Cerebral thrombosis
Cerebral embolism
Forms of Cardiovascular Disease:
Stroke
• Hemorrhagic stroke
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Intracerebral hemorrhage
Subarachnoid hemorrhage
Vessel in or on brain ruptures
Arises from aneurysms (secondary to hypertension
or atherosclerotic damage)
• Rupture  ischemia and pressure on brain
tissue  death of brain tissue
Forms of Cardiovascular Disease:
Stroke
• Effect of stroke depends on region affected
– Paralysis on one side most common
– Each side of brain controls opposite side of body
• Strokes in right brain
– Vision problems, memory loss
– Quick, inquisitive behavior
• Strokes in left brain
– Speech/language problems, memory loss
– Slow, cautious behavior
Forms of Cardiovascular Disease:
Heart Failure
• Chronic, progressive weakening of the heart
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Too weak to maintain cardiac output
Results from damage to and overworking of heart
Hypertension major contributor (75% of cases)
Other causes: atherosclerosis, valve diseases, viral
infection, MI
• Causes edema, pulmonary edema
• Ultimately requires heart transplant
Forms of Cardiovascular Disease:
Other Cardiovascular Diseases
• Peripheral vascular diseases
– Arteriosclerosis (obliterans)
– Varicose veins, phlebitis
• Valvular diseases
– Often from viral infections
– Rheumatic heart disease
• Congenital heart disease
– Congenital defects
– Can affect aorta, valve, or septum
Understanding the Disease Process:
Coronary Heart Disease
• Pathology of CHD affects vessel wall
– Tunica intima: endothelium
– Tunica media: smooth muscle cells, elastin
– Tunica adventitia: collagen
• Early theory: initial injury to endothelium
– Platelets, monocytes adhere to injury (PDGF)
– Smooth muscle cells and lipids migrate to intima
– Collection of debris in intima  plaque
Figure 21.4
Figure 21.5
Understanding the Disease Process:
Coronary Heart Disease
• Recent theory: monocytes attach between
endothelial cells
– Become macrophages
– Ingest oxidized LDL-C
– Become large foam cells, form fatty streaks
• Endothelial cells slough off
– Expose underlying connective tissue
– Allows platelets to attach
– Endothelial injury not always precipitating event
Understanding the Disease Process:
Coronary Heart Disease
• Endothelial injury or disruption comes from
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High blood LDL
Free radicals from cigarette smoke
Hypertension
High plasma homocysteine
Infectious microorganisms
• Atherosclerosis now considered to be
inflammatory disease
Understanding the Disease Process:
Coronary Heart Disease
• Plaque consists of
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Smooth muscle, inflammatory cells, lipids
Fibrous cap (thick or thin)
Thin caps = more unstable = easier rupture
Rupture  thrombus formation
• Rupture and thrombus account for 70% of
MIs
• Plaques are dynamic (erode, repair, grow)
Figure 21.6
Understanding the Disease Process:
Hypertension
• Poorly understood condition
• 90 to 95% of cases idiopathic
• Remaining 5 to 10% secondary to other
issues
– Kidney disease
– Adrenal tumors
– Congenital defect of aorta
Determining Individual Risk
• Epidemiology of CHD and hypertension
reveals relationships among disease factors
– Large-scale public studies, often longitudinal
– Framingham Heart Study
• Epidemiology does not define causal
mechanisms of cardiovascular disease
• Epidemiology does provide researchers
with valuable insights into disease risk
factors
Determining Individual Risk:
Coronary Heart Disease
• Uncontrollable CHD risk factors
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Heredity, family history
Race
Sex (male > female)
Age
• Must try to mitigate risk via controllable
CHD risk factors instead
Determining Individual Risk:
Coronary Heart Disease
• Controllable CHD primary risk factors
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Tobacco smoke
Hypertension
Abnormal blood lipid profile
Physical inactivity
Obesity, overweight
Diabetes, insulin resistance
• As number of risk factors , risk of CHD 
Determining Individual Risk:
Coronary Heart Disease
• Other putative CHD risk factors
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C-reactive protein (CRP)
Fibrinogen
Homocysteine
Lipoprotein(a)
• Inflammatory processes and markers may
be involved in risk
Table 21.3
Determining Individual Risk:
Coronary Heart Disease
• Blood triglycerides
• Blood cholesterol
• Lipoproteins
– VLDL cholesterol (risk factor)
– LDL cholesterol (risk factor)
– HDL cholesterol (beneficial)
• Ratio of total cholesterol to HDL (best
index)
Determining Individual Risk:
Early Detection of CHD Risk Factors
• Early detection  preventive treatment
• In boys 8 to 12, girls 13 to 15 years old
– 19.8% had total cholesterol >200 mg/dL
– 5.2% had abnormal resting ECGs
– 37.5% had 20+ percent body fat
• High risk in childhood  high risk as adult
Determining Individual Risk:
Hypertension
• Uncontrollable risks similar to those for
CHD
• Controllable risk factors for hypertension
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Insulin resistance
Obesity, overweight
Diet (sodium, alcohol)
Tobacco use
Oral contraceptives
Stress
Physical inactivity
Determining Individual Risk:
Metabolic Syndrome
• Metabolic syndrome
– Also called insulin resistance syndrome
– Links CHD, hypertension, abnormal blood lipids,
type II diabetes, and abdominal obesity to insulin
resistance and hyperinsulinemia
– Series of correlations and associations
• Possible causes
– Obesity and insulin resistance trigger cascade of
events
– Systemic inflammation
Reducing Coronary Heart Disease
Risk Through Physical Activity
• Epidemiological evidence
– Risk of MI 2 to 3 times higher in sedentary
populations
– Both occupational and leisure activity
– Similar results for both men and women
• CDC findings
– Physical inactivity equal to other risk factors
– Sedentary lifestyle 3 times more common than other
major risk factors (smoke, hypertension, cholesterol)
Reducing Coronary Heart Disease
Risk Through Physical Activity
• How much physical activity  risk of CHD?
– Physical activity versus physical fitness
– Physical activity more important than fitness
• Walking and gardening—examples of lowimpact, low-level activity   risk
• More vigorous exercise may yield greater
benefits
Reducing Coronary Heart Disease
Risk Through Physical Activity
• Exercise type and intensity related to CHD
risk
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Run 6 mph for 1 h per week  42%  risk
Weight train 30 min per week  23%  risk
Brisk walk 30 min per day  18%  risk
Swimming and cycling unrelated to risk
• Higher intensity  greater risk reduction
Reducing Coronary Heart Disease
Risk Through Physical Activity
• Physical fitness and physical activity may
be independent risk factors for CHD
– Higher fitness and activity both reduce risk
– Fitness more potent than activity
• Controversial findings, merit more research
Reducing Coronary Heart Disease
Risk Through Physical Activity
Reducing Coronary Heart Disease
Risk Through Physical Activity
• Physiological adaptations to exercise that
may reduce risk
–  Contractility via LV hypertrophy
–  Diameter and capacity of coronary vessels
–  Endothelial function and vasodilation
–  Vascular inflammation
• Exercise  enhanced cardiac and vascular
function (even with atherogenic diet)
Reducing Coronary Heart Disease
Risk Through Physical Activity
• Exercise  reduced risk factors
–  Blood pressure (systolic, diastolic)
–  LDL, total cholesterol
–  HDL cholesterol
–  Blood triglycerides
–  Total cholesterol relative to HDL
• Exercise exerts biggest effect on blood lipid
profile risk factors
Reducing Coronary Heart Disease
Risk Through Physical Activity
• Effect of exercise on other risk factors
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Weight control
Diabetes management
Stress reduction
Anxiety reduction
• Note: effects of exercise on blood-related
risk factors also reflect exercise effects on
plasma volume and body weight
Reducing Hypertension Risk
Through Physical Activity
• Effect of exercise on hypertension not as
well established as effects on CHD
• Epidemiological evidence
– More active people in studies had lower systolic and
diastolic pressures
– Highly fit individuals less prone to hypertension
– Hypertension associated with low fitness
Reducing Hypertension Risk
Through Physical Activity
• Physiological adaptations to exercise
–  Plasma volume (does not  blood pressure)
–  In overall sympathetic nervous activity
–  Vasodilation and vascular remodeling
• Physiological mechanisms that lower blood
pressure still poorly understood
Reducing Hypertension Risk
Through Physical Activity
• Exercise  reduced risk factors
–  Body fat
–  Blood glucose levels
–  Insulin resistance
•  BP unrelated to duration of training
•  BP may be greater with low or moderate
intensity
Risk of Heart Attack and Death
During Exercise
• Infrequent but highly publicized
• Risk very, very low
– Men: 1 death per 1.42 million h of exercise
– Women: 1 death per 36.5 million h of exercise
• Habitual exercise   risk of death
• When death occurs, age affects cause
– Under 35: more often genetic abnormalities,
aneurysm
– Over 35: more often arrhythmia caused by CHD
Figure 21.8
Risk of Heart Attack and Death
During Exercise
• CPR outside of hospital increases survival
of cardiac arrest by 2 to 3 times
• Bystanders rarely perform CPR
– Fear of doing it wrong
– Fear of legal liability
– Fear of infection from rescue breathing
• Chest compressions without breathing 
better survival outcomes than traditional
CPR
Exercise and Rehabilitating Patients
With Heart Disease
• Endurance training  changes that reduce
work, O2 demand of heart
• Aerobic exercise helps prevent future
complications
–  Capillary:muscle fiber ratio
–  Plasma volume
–  Or maintain O2 supply to heart
–  Blood flow to heart
–  LV function
(continued)
Exercise and Rehabilitating Patients
With Heart Disease (continued)
• Aerobic exercise helps prevent future
complications
–  Blood pressure
–  Blood lipid values
–  Body fat
–  Glucose control
–  Stress
• Combining resistance training and aerobic
exercise optimal
Exercise Training and Rehabilitating
Patients With Heart Disease
• Comprehensive program consists of
– Exercise, physical activity
– Counseling (nutritional, psychological, sexual)
– Support forums
• Exercise rehabilitation improves outcomes
– 20% lower total mortality and 26% lower risk of
death from subsequent MI
• Rehabilitation patients should have medical
evaluation, GXT, exercise prescription
Table 21.4