Chapter 10: Heart Disease
I. Heart Disease
A. CVD comprises diseases of the heart and BV
1. a general name for more than 20 different diseases of the heart and BV
2. Box 10.1 Glossary of terms used in Heart disease
3. Leading killer of people in the US; about 1 million deaths annually. 40% of deaths caused by CVD
4. 25% of people live today with some form of CVD
5. survey of 90,000 adults only 18% had no risk factors for CVD
6. removing all forms of CVD risk factors would increase age about 10 years
7. Athersclerosis is the underlying factor in 85% of CVD
a. when it blocks one or more of coronary BV it is CHD
8. blood clot forms in the narrowed coronary artery blocking the BF to the part of the heart causing a MI; 1/3 die as a result of MI
9. Atherosclerosis can block BV to the brain causing stroke or to the legs (peripheral artery disease).
10. Stroke kills 150,000 americans each year
11. Peripheral artery disease affects up to 20% of older people and leads to pain in the legs brought on by walking (intermittant claudication; limping lameness)
12. Atherosclerotic plaques range from small yellow streaks to advanced lesions with ulceration, thrombosis (formation or existence of a blood clot within the BV), hemorrhage, and calcification
13. Several stages of dev. Of atherosclerosis
a. arterial wall is injured by a variety of factors including high BP, hypercholesterolemia, oxidized LDL, cigarette smoking, toxins, and viruses and blood flow turbulence
b. lead to change or impairment in the normal function of the endothelium and chronic inflammatory response ensures.
c. in response to injury, monocytes and T cells penetrate through the endothelium into the underlying intima layer.
d. monocytes are converted to macrophages, scavenger cells that ingest oxidized LDL and other substances.
e. key to the entire process is the malign interation of LDL particles especially the oxidized form with the endothelium and the monocytes
f. the injured and impaired endothelial cells attract platelets and begin to release growth factors that stijmulate the migration of smooth muscle cells from the outer layers of the artery wall into the intima, where they prolifereate abnormally.
g. the macrophages and smooth muscle cells begin to release collagen and other proteins, which form the fibrous component of atherosclerosis. The engorged foam cells then die and release cholesterol debris into the artery wall.
h. The mature plaque is made up of a complex mixture of foam cells, smooth-muscle cells, cholesterol debris, and fibrous proteins.
i.over time the plaque becomes hardened or calcified and then develop cracks and ulcers, prompting the formation of blood clots that can suddenly close up the narrowed artery lumen, causing heart attack.
II. Coronary Heart Disease
A. CHD also referred to as CAD is the major form of heart disease
B. Coronary arteries supply the heart
C. The narrowing, hardening, and blocking of these arteries by atherosclerosis leads to CHD.
D. A blood clot may form in a narrowed coronary artery and block flow of blood to the part of the heart muscle supplied by that artery, referred to as a myocardial infarction.
E. Chest pain, angina pectoris, can occur during emotional excitement and exercise
F. RPP, rate pressure product, SBP X HR
III. Stroke
A. CV disease that affects the BV supplying oxygen and nutrients to the brain.
B. Arteries in the brain may become narrow due to athersclerosis
C. Clots can then totally block the BF causing the stroke
a. two types of clots:
b. thrombus that forms in the area and narrows the vessel
c. embolus a clot that floats in from another area
D. ¾ of strokes are caused by clots
E. hemorrhagic stroke from anuerysms
F. 500,000US suffer a new stroke or recurrent stroke every year
a. 30% who have a stroke will die within a year
b. 60% within 8 years will die
c. 150,000 US die each year of stroke; 1 in 15 deaths in the US each year
d. Third largest cause of death
e. Survivors, ½ suffer long-term disabilities needing help caring for themselves and assistance walking
G. AHA, the best prevention is reduction of CHD risk factors
a. 70% of stroke caused by high BP
b. stroke risk varies directly with BP
c. other risks, cigarette smoking, obesity, excessive alcohol consumption, high blood cholesterol, diabetes mellitus, and physical inactivity
d. Strongly related to age with highest death rates over 85 years
e. 19% higher for men than women
f. 60% more risk for Blacks than European Americans
g. Warning signs: unexplained dizziness, weakness or numbness on one side of the body, face, arm, or leg; temporary loss of speech, temporary dimness or loss of vision in one eye, or sudden sever headaches.
H. 10% of strokes are preceded by little strokes called TIAs, transient ischemic attacks.
a. 36% of those with TIAs will have strokes
IV. Trends in CV Disease
A. from 1920-1950 sharp rise in deaths from Heart disease, primarily acute MI in men
B. causes unknown, however, the use of the car, increased use of saturated fats and cigarettes
C. 1953, autoposies in US soldiers, average age 22, 77.3% of hearts showed some gross evidence of coronary atherosclerosis. 12.3% had plaques causing luminal narrowing of more than 50%.
D. Since 1950 the trend has reversed with a sharp fall in deaths, by 55% form ’50 to ’95.
E. Death rate from stroke has been dropping for 65 years due to better control of hypertension through lifestyle adjustments and modification
V. Risk factors for Heart disease
A. In 1998 obesity, diabetes and physical inactivity were added to the major risk factor category from the contributing category.
B. Table 10.2
1. Major risk factors that can be changed
a. cigarette smoking 25%
b. high BP 24% (>140/90)
c. High blood cholesterol 19% (>240 mg/dl)
d. Physical inactivity 60%
e. Obesity 35% (BMI >25kg/m2)
2. potential risk factors include:
a. stature
b. baldness
c. low social support
d. postmenopausal hormone therapy
e. high uric acid levels
f. high plasma levels of homocysteine
g. hyperinsulinemia
h. high levels of blood fibrinogen
i. emotional distress
j. hostile personality
k. many others
3. figure 10.2 proportions of coronary heart disease deaths attributable to 5 major risk factors:
a. high cholesterol 43%
b. inactivity 34%
c. obesity 32%
d. hypertension 29%
e. cigarette 25%
VI. Treatment of Heart disease
A. myocardial Ischemia, not enough blood flow to an area of the heart
B. may feel angina pectoris, which can be treated with drugs
C. Nitroglycerine relaxes the veins and coronary arteries
D. Invasive techniqes
1. angiography using catheters, since 1959
2. coronary artery bypass graft surgery
3. 1977, Percutaneous transluminal coronary angioplasty
a. PTCA performed 400,000 times per year, less expensive but 25-50% of patients the arteries renarrow within 6 months
b. CABGS performed 500,000, costing over $44,000 on average
4. laser angioplasty
5. directional coronary atherectomy
6. coronary stent
E. Can atherosclerosis be reversed without surgery?
1. intensive drug and diet therapy to lower LDL and raise HDL retards the progression of coronary atherosclerosis, promotes regression and decreass the incidence of coronary events
2. diet alone can retard the overall progression and increase overall regression of CAD
3. regression is likely in patients who experience 2200 calories per week in exercise (5-6 hours weekly)
V. Cigarette Smoking
A. The single most preventable cause of premature death in the US
B. A leading cause of death, followed by diet and inactivity, then alcohol
C. 1 out of 5 deaths attributable to cigarette smoking
D. Smoking kills more through CV diease than through cancer
E. 10 million suffer from chronic bronchitis, emphysema, peptic ulcer, and arteriosclerosis
F. smoke free society could increase life expectancy of 15 years in the lives of over 400,000 individuals who would have died by tobacco-related deaths
G. risk factor for CVD, CHD, stroke, and peripheral artery disease.
H. Exposure to tobacco smoke causes abnormalities in endothelial cell function, promotes formation of blood clots, decreases HDL levels and increases the stiffness of both muscular and elastic arteries.
I. Recent trends:
1. Percentage of smokers has dropped since 1965
a. from 60.4% to 33.7% in Black men
b. from 51.1% to 27.7% in white men
c. from 33% in black and white women to 23.7% in white women, and 21.7%in black women
2. many adverse health effects are related to passive smoking and can be a cause of premature death in non-smokers
3. 3000 deaths per year can be attributed to effects of second hand smoke
4. parental smoking causes 300,000 lung infections, including bronchitis, pneumonia, among children each year.
5. increases severity of asthma in children
J. Smokeless tobacco
1. snuff, taken through nose; or chewing tobacco which has tripled in use from the ‘70s to the 90’s.
2. 5.3 million adults are users; highest among 18-24 year olds; 1 in 5 high school males
3. oral cancers are prevalent; white patches of leukoplakia present in 46% of professional baseball players who use chewing tobacco, can become cancerous.
4. other effects: reproduction, longevity, abrasion of teeth, gum recession, periodontal bone loss and tooth loss, highly addictive
K. smoking cessation
1. nicotine is highly addictive and is one of the most difficult of all health behaviors to change.
2. US Agency for Health Care Policy and Research Guidelines, page 356.
a. every person who smokes should be offered a smoking cessation treatments at every visit to a physician
b. Clinicians should ask about and record the tobacco use status of every patient
c. cessation treatments even as brief as 3 minutes per visit are effect
d. more intense treatment is more effective in producing long term abstinence from tobacco.
e. nicotine replacement therapy, clinician delivered social support, and skills training are the 3 most effective components of smoking cessation treatment.
f. health care systems should make institutional changes that result in the systematic identification of and intervention with all tobacco users at every visit.
3. after 15 years off cigarettes the risk of death returns to levels of those who never smoked
4. after 1 year off cigarettes the excess risk of heart disease reduced by half
5. risk of lung cancer for exsmokers drops ½ for every 10 years.
6. exsmokers have fewer days of illness, and health complaints, better overall health status, and fewer lung problems.
L. Exercise and Tobacco
1. lower incidence of smoking among adolescents involved in vigorous physical activity and interscholastic sports
2. youths that smoke exercise less and are more involved in other high-risk behaviors.
3. smokers exercise less; it is more difficult for them
4. smoking is associated wth a decrease in the ability to perform vigorous exercise because of decreased lung function, increased blood levels of carboxyhemoglobin, a blunted heart rate response to exercise, and a decreased max VO2.
5. resting HR and BP are elevated due to nicotine and decreases Q and increases oxygen demand of the heart.
6. nicotine increases lactate levels in the blood during exercise which gives a fatigued feeling.
7. resistance to air flow after smoking is increased in the lung passageways.
8. Cooper – smokers who get involved in aerobic exercise become more aware of how smoking has decreased their ability to process oxygen. They find they become winded more easily than their fellow exercises. This helps creaste a desire to quit smoking.
9. Kaiser permanente study – those who had participated in a smoking cessation program who had increased their exercise after trying to quit were more likely to be nonsmokers in a year.
10. fear of gaining weight
11. coping with stress
12. nicotine withdrawal
a. irritability, depression, anxiety, impatience, disrupted sleep, and impaired ability to work.
b. Peaks within 24 hours then gradually decreases for about 1 month
13. smokers who maintain a high level of physical fitness have lower death rates from all causes than do low-fitness smokers.
VI. Hypertension
A. 140/90 or higher on two separate occasions
B. gradual increase with age; about 2/3 of americans have this disease in old age
C. In societies where salt and alcohol intake is high, potassium intake is low, physical inactivity and obesity is the norm hypertension is high
D. 43 million americans have high blood pressure
E. Health problems
1. kills 37,000 americans each year and contributes to the deaths of 700,000
2. increases risk of CHD, stroke and kidney failure
3. LVHypertrophy
4. Anuerism formation in the brain
5. BV in kidneys to narrow
6. Arteries throughout the body to harden faster, especially in the heart, brain, and kidneys
F. Use of drugs to control hypertension is a lifelong commitment because it does not cure it.
a. Lifestyle changes are the only way to cure it.
b. Non compliance in drug therapy
c. Treatments are expensive
d. Cannot reach or be successful with all hypertensives
e. Some drugs have side effects on blood lipids, and lipoprotein levels
f. Beta blockers lower HDLs and raise triglycerides
g. 40% of hypertensives have high blood cholesterol levels
h. a population shift downward of the BP by 2 mm Hg would reduce annual mortality from stroke by 6% and CHD by 4%
i. strategy to focus on those most needful of it
j. Drug therapy TABLE 10.5
k. Figure 10.28 Lifestyle vs lifestyle + drug therapy
1) with lifestyle changes the SBP decreased 10.6 and DBP decreased 8.1 mmHg
2) with lifestyle + drug therapy SBP decreased 19 and DBP 13
G. Lifestyle modifications to lower BP
1. Box 10.4
a. lose weight if overweight
b. limit alcohol to no more than 1 oz. Per day.
1) > 14 drinks /week considered heavy drinkers
2) effects almost every organ system in the body; liver, GI tract, inflame the esophagus and pancreas, exacerbate exiting peptic ulcers and cause some cancers (e.g. breast cancer in women)
3) nutritional deficiencies
4) effects immune system, endocrine, and reproductive functions; neurological problems including dementia, blackouts, seizures, hallucinations, and peripheral neuropathy
5) 3rd leading cause of death in the US; > 100,000 deaths per year due to accidents, cancer, and liver disease; and violence
6) 1 drink per hour will produce a BAL of .02 in 150 # person; 5 consumed in 1 hour will prduce a BAL of .10
7) alcohol lowers risk from CHD for both men and women; 20-50%
8) more than 2 drinks per day was associated with a 47% reduction in risk of coronary heart disease.
9) Table 10.8 a depressant, but a stimulant early
10) Raises HDL and reduces blood clotting
11) But alcohol can cause some changes in heart tissue
12) 2-6 drinks per day are associated with the highest risk of death. 2 drinks increase mortality by 50%; the gains in reduced mortality of CHD are offset by increased death by other cancers
13)
c. Increase aerobic activity 30-45 minutes most days per week
d. Reduce Na intake to no more than 2.4 gm or 6 g NaCl
1) tsp = 5g and has 2000 mg of Na
2) learn to read food labels
3) fruits and vegetables
4) a ratio of 3:1 Na:K may reduce BP by excreting Na in urine
e. Maintain intake of K
f. Maintain intake of Ca+ and Mg
g. Stop smoking and reduce intake of saturated fat and cholesterol
2. Weight loss is the single most effective way to reduce BP
3. Physical activity
a. hypertensive response to GXT by normotensive; increased prevalence of hypertension of 2.1 to 3.4 times
b. 8-10 mm SBP and 6-10 mm DBP reduction with aerobic exercise
c. medications to control BP can be reduced substantially as patients continue to exercise
d. effects of exercise on hypertension occur quickly with in the first 3 weeks, but further reduction will take months
e. frequency should be nearly every day.
f. weight training should not be the only exercise mode; higher repetitions are better ~ 10-15 reps
VII. High Blood Cholesterol
A. A major Coronary risk factor
1. body makes its own cholesterol
2. gets cholesterol primarily from animal products
3. cholesterol is essential for formation of bile acids, some hormones, and is a component of cell membranes and nerve tissue
4. excess cholesterol in the form of LDL or VLDL may be deposited in the arterial walls
5. for every 1% reduction in blood cholesterol there is a 2-3% drop in the risk of CHD
B. Prevalence of High Blood Cholesterol
1. everyone should know their blood cholesterol levels and have it checked every 5 years, or every year if high risk for heart disease
2. Blood cholesterol categories
a. desirable < 200 mg/dl
b. borderline high 200 – 239 mg/dl
c. high > 240 mg/dl
d. optimal < 160 mg/dl
e. Framingham Heart Study – continuous study from the 50’s concluded that it is very rare when blood cholesterol is within the optimal zone
C. Description of lipoproteins
1. lipoproteins to transport cholesterol and triglycerides
a. High Density lipoproteins
1) 30% phospholipids
2) 18% cholesterol
3) 2% triglycerides
4) 50% Protein: apoproteins A-I, A-II
5) HDL acts as a shuttle taking up cholesterol from the blood and body cells and transfers it to the liver to form bile acids
6) Bile acids may pass out with the stool which helps the body rid itself of excess cholesterol
7) HDL-C < 35 mg/dl is a risk factor with optimal values > 60.
8) A 1% rise in HDL concentration reduces coronary risk by 2-3%
9) People with the highest HDL-C have heart disease death rates 2-3 times lower than those with the lowest HDL levels
10) Women average HDL levels ~ 56 mg/dl; Men ~ 46 mg/dl
11) Higher among blacks
12) HDL expressed as a percentage of total cholesterol, or as a ratio of Total cholesterol/HDL
a) ratio below 3 is optimal; 5 or above is high risk; for every unit ratio drop the risk of CHD drops 53%
b) average male has a 4.6 ratio; average female 4.0 ratio
c) elderly, obese, and smokers have higher ratios
d) females, alcohol users, blacks and active people have lower ratios
b. Low density lipoproteins
1) 23% phospholipids
2) 43% cholesterol
3) 9% triglycerides
4) 25% Protein: apoproteins; B
5) formed from VLDL when it gives up its triglycerides to body cells
6) excess LDL contributes to atherosclerosis
7) Categories:
a) desirable < 130 mg/dl
b) borderline – high 130 – 159 mg/dl
c) high - > 160 mg/dl
d) optimal < 100 mg/dl
c. Very Low Density Lipoproteins
1) 12% phospholipids
2) 15% cholesterol
3) 60% triglycerides
4) 13% Protein
2. Apoproteins is the protein part of lipoproteins which are important in activating or inhibiting enzymes involved in metabolizing fats
3. Serum Triglyceride levels as a risk factor is less clear
a. normal triglyceride <200 mg/dl
b. borderline-high triglyceride 200-399 mg/dl
c. high triglycerides 400-1000 mg/dl
d. very high triglycerides > 1000 mg
e. optimal <110 mg/dl; athletes usually below 80 mg/dl
f. not as good a predictor
g. people with low HDL, diabetes, obesity, and hypertension the risk of heart disease increases as triglyceride levels increase
h. triglyceride levels can be lowered by losing weight, aerobic exercise and reducing alcohol consumption
4. LDL is calculated and not measured, from the HDL, triglyceride and total cholesterol levels
a. total cholesterol is equivalent to the cholesterol in all three
b. LDL is estimated by multiplying the triglycerides by 20%
LDL-C = total chol - [HDL-C + (0.20 X triglycerides)]
If total chol = 200 mg/dl, HDL-C is 50 mg/dl, triglycerides = 100 mg/dl:
LDL-C = 200 – [50 + (0.20 X 100)] = 130 mg/dl
D. Treatment of hypercholesterolemia
1. National Cholesterol Education Program detection and treatment recommendations, figure 10.47
2. Dietary therapy, a minimum of 6 months of intensive dietary changes, exercise and weight control, and counseling.
3. Step 1 diet: fat calories <30%; saturated fat <8-10%; dietary cholesterol < 300 mg/day for 3 months
4. Step 2 diet: dietary cholesterol < 200 mg/day; saturated fat < 7%
5. Drug therapy if LDL-C remains high: table 10.10 summarizes dietary and drug treatment decision guidelines
6. Elderly persons in good health not excluded from therapy, except patients of advanced age or those with sever competing illnesses.
a. Drug therapy the statins (Lovastatin, pravastatin, simvastatin) are highly effective in reducing LDL and raising HDL-C and well tolerated for the long term use
b. Other classes of drugs include: bile acid resin, nicotinic acid, and estrogen replacement for women.
7. Diet and other lifestyle measures
a. Box 10.5
b. Antioxidants reduce oxidized LDL-C
c. Fat and cholesterol in food
d. Lifestyle factors that increase HDL-C
1) aerobic exercise at least 90 minutes per week
2) weight reduction and leanness
3) smoking cessation
4) moderate alcohol consumption
e. runners showed and increase in HDL with relationship between miles per week and HDL conc. No plateau
f. Lifestyle factors that reduce LDL-C and Total Cholesterol
1) reduction of dietary saturated fat intake (especially meat and dairy fats) and of intake of trans fatty acids (mainly found in hydrogenated fats)
2) reduction in body weight
3) reduction in dietary cholesterol intake (found in all animal fats)
4) increase in dietary polyunsaturated and monounsaturated fatty acids (mainly from plant foods, fish and olives)
5) increase in carbohydrate and dietary water-soluble fibers (especially fruits and vegetables, beans, and oat products)
6) control of stress (weak evidence)
7) reduction of dietary caffeine, coffee consumption (weak evidence)
g. weight loss has a powerful effect on blood fats and lipoproteins.
1) total cholesterol, LDLs and triglycerides decrease greatly
2) HDLs increase only when weight loss has been maintained and stabilized
3) estimates are that for every pound lost there is a 1 mg/dl drop in total cholesterol
4) with diet and body weight controlled, exercise trianing can be expected to increase HDLs, decrease triglycerides, no effect on LDLs
h. exericse of at least 30 minutes per session 3X per week or about 1000 calories of moderate to high intensity aerobic type exercise is require to produce favorable changes in blood fats and lipoproteins
i. women require greater volumes of exercise than men to improve their HDL because women have initially higher levels of HDL-C
j. figure 10.54 formation and elimination of HDL
a) HDL is formed in the blood by two enzymes: LPL, and lecithin: cholesterol acyltransferase.
b) It is taken out of circulation by Hepatic Lipase.
c) Active people have higher LPL and LCAT and lower HL enzyme activity levels
k. Single bouts of exercise increase HDL and lower triglycerides figure 10.55, changes last about 24-48 hours
l. Lipoprotein Lipase in the walls of the capillaries breaks down the triglycerides during exercise allowing the muscles to take in fat for fuels.
VIII. Exercise and CHD prevention
I. Intro
A. Physical inactivity affects CHD risk to the same degree in men and women
B. CDC now promotes aerobic exercise asmuch as blood pressure control, dietary improvements to lower serum cholesterol and control weight, and smoking cessation.
C. Those that exercise regularly generally have the other risk factors under control
D. Coronary arteries expand more, less stiff with age, and wider than those of unfit subjects
E. May decrease the potential for clot formation
F. Exercise must be regular in order for the CHD risk to be lowered.
G. The greatest benefit to lowering CHD risk occurs when sedentary people adopt moderate physical activity habits, with some additional protection gained as the duration and intensity of the exercise is raised
IX. Exercise and Stroke prevention
I. Intro
A. AHA does not consider physical inactivity as a primary risk factor for stroke
B. It is a secondary risk factor
C. Reduces risk indirectly by reducing the risk of CHD; and atherosclerosis
D. 15 major studies show a link between physical activity and reduced risk for stroke
X. Cardiac Rehab
I. 1.5 million americans each year have a heart attack
A. People who survive the acute stage of a heart attack have a chance of illness and death 3 to 9 times higher than the general population
B. During first year after a heart attack 27% of men and 44% of women will die
C. 11 million americans have a history of MI, angina pectoris, or both
D. 4.4 million total vascular and cardiac surgeries per year, including diagnostic catheterizations, coronary artery bypass graft surgery, angioplasty, open-heart surgery, heart transplants, and pacemaker insertions.
E. Cardiac rehab programs include those with CHD, those who have had a MI, and post surgical
F. Goal is to prepare cardiac patients to return to productive, active, and satisfying lives, with a reduced risk of recurring health problems
G. Emphasis is on lifestyle change, optimization of drug therapy, vocational counseling, and group and family therapy.
H. Lifestyle change includes exercise, weight control, dietary therapy, smoking cessations
I. Patients with no complications are expected to progress from phase I through phase III within one year after an acute cardiac event. Phase IV is designed for lifelong exercise participation.
1. Phase I – easy walking, and bed exercises during 5-14 days while patient is in a coronary care unit of the hospital.
2. Phase II – is an outpatient program lasting 1-3 months, with patient exercising aerobically in the hospital or clinic under careful supervision
3. Phase III – lasts 6-12 months and is a supervised aerobic exercise program in a community settting.
J. Exercise programs are highly individualized, with initial slow, gradual progression of exercise duration and intensity.
K. 3 days per week, 20-40 minutes at a moderate comfortable intensity
L. Low intensity resistance exercise
M. Only 15% of eligible cardiac patients actually participate in cardiac rehab programs.
N. Phases II and III must be done at a site like a hospital or fitness center, transportation, time obstacles
O. Home based programs are attractive alternatives and provide a convenient setting that can also involve family support
P. VO2 max improves by an average of 20%, anginal symptoms disappear or are greatly reduced, but length of life is not yet proven.
Q. Estimated risk of MI in a cardiac program is 1 in 294,000 and death risk is 1 in 784,000. Over 80% of patients who had an MI were successfully resucitated.