Download Chapter 14: Cardiovascular Diseases: Understanding Risks and

Chapter 14
Cardiovascular Diseases: Understanding Risks and Measures of Prevention
Learning Objectives
1. Describe how the heart functions.
2. Define cardiovascular disease, infarction, coronary heart disease, stroke, and heart attack.
3. Explain the role atherosclerosis plays in heart disease.
4. Identify and explain types of heart surgeries used to repair blocked arteries.
5. Identify the major risk factors of heart disease that cannot be changed, major risk factors that
can be changed, and other contributing factors.
6. Explain the role of homocysteine in heart disease.
7. Discuss various ways to reduce cholesterol levels.
8. Explain how stress contributes to hypertension.
9. List dietary supplements and foods that help maintain a healthy cardiovascular system.
Key Terms
Aneurysm (319)
Angina pectoris (315)
Antioxidant (327)
Aorta (314)
Arteries (313)
Arteriosclerosis (315)
Atherosclerosis (315)
C-reactive protein (CRP) (323)
Capillaries (313)
Cardiac catheterization (316)
Cardiologist (314)
Cardiopulmonary resuscitation (CPR) (318)
Cardiovascular disease (312)
Carotid endarterectomy (320)
Coronary arteries (312)
Coronary artery bypass surgery (316)
Diastole (324)
Essential (primary) hypertension (323)
Familial hyperlipidemia (FH) (322)
Fibrillation (314)
Free radicals (327)
Heart attack (312)
High-density lipoprotein (HDL) (320)
Hypertension (323)
Infarction (312)
Ischemia (312)
Low-density lipoprotein (LDL) (320)
Metabolic syndrome (325)
Myocardium (313)
Open-heart surgery (316)
Pacemaker (314)
Percutaneous transluminal coronary angioplasty (PTCA) (317)
Plaque (315)
Secondary hypertension (323)
Sinoatrial node (314)
Statins (323)
Stroke (312)
Systole (324)
Type A behavior (326)
Varicose veins (314)
Veins (313)
Chapter Summary
The heart is a pump that maintains blood circulation in the arteries and veins. The arteries carry
oxygen and nutrients to all body cells, and the veins carry carbon dioxide and waste products
back to the lungs to exchange for fresh oxygen. Valves in the heart and blood vessels keep blood
circulating in one direction.
Cardiovascular disease accounts for more than 40% of all deaths and is the leading cause of
death in the United States. Many risk factors are associated with the development of arterial
disease, which eventually can result in a heart attack or stroke. High blood pressure, cigarette
smoking, excessive cholesterol in the blood, lack of exercise, overweight, and stress may
contribute to the development of cardiovascular disease. Although all these risk factors are
significant, poor nutrition, stress, and smoking stand out as major factors for hypertension, heart
attack, and stroke.
Heart and vascular disease are preventable. In some human societies, people rarely have heart
disease, even as they get older. The lifestyle of modern civilization seems to be the chief cause of
death from cardiovascular diseases. Coronary bypass surgery and antihypertensive drugs are of
debatable value. Prevention is the key to the continued health of the heart and vascular system.
Every person can examine his or her lifestyle and try to reduce or eliminate those factors that
contribute to the risk of developing heart disease.
Lecture Outline
Understanding Cardiovascular Diseases
•
The term refers to a number of conditions that damage the heart or arteries.
– Heart attack—If the coronary arteries (large blood vessels that carry blood to and
from the heart) become diseased or blocked, a heart attack may result.
– Infarction—If the heart does not receive a continual supply of blood and oxygen,
the heart cells die.
– Ischemia—This occurs when the blood supply to the heart is only partially
blocked.
•
The term refers to a number of conditions that damage the heart or arteries.
– Stroke—Occurs when there is damage to the brain from an insufficient supply of
blood to the brain cells.
•
Cardiovascular diseases are preventable and are primarily lifestyle diseases.
•
The Heart and Blood Vessels
– Arteries—Carry oxygenated blood from the heart to all organs and tissues in the
body
– Veins—Return blood to the heart after oxygen and nutrients have been exchanged
for carbon dioxide and waste products
– Capillaries—Tiny blood vessels that branch out from arteries and veins, and
circulate blood to all the cells in the body
– Myocardium—Muscular wall of the heart
– Heart
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Upper two chambers are called the left atrium and right atrium.
•
Lower two chambers are called the left ventricle and right ventricle.
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Blood that is depleted of oxygen returns to the heart via the right atrium.
•
It flows to the right ventricle and is pumped to the lungs, where it is
reoxygenated and returned to the left atrium via the pulmonary vein.
•
This fresh blood is pumped throughout the body’s tissues from the left
ventricle through the large artery called the aorta.
– Heart Rhythm
•
Beats 60–100 beats per minute
•
Controlled by the sinoatrial node in the right atrium
– Sends an electrical signal across the surface of the heart which
causes the fibers to contract
•
The brain can affect the heart’s rate, as well
•
Arrhythmia—irregular heartbeat
•
Atrial fibrillation—when signals other than those coming from the
sinoatrial node interfere with the heartbeat and cause different areas of the
heart to beat independently of one another
– No coordinated contraction = improper pumping of blood
– Defibrillators: External and Implanted
– AED—automated external defibrillator
•
Kept in public places for individuals to use on someone whose heart is in
defibrillation
– ICD—implantable cardioverter defibrillator
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A small unit implanted in the chest with wires attached to the heart that
deliver an electrical shock if necessary to restart the heart
•
Most people who have these do not ever need an electrical shock
– Regulating Blood Flow
– The cardiovascular system is equipped with one-way valves in the chambers of
the heart and blood vessels.
– With every heartbeat, the valves open and close to allow blood to flow in one
direction.
Atherosclerosis
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Hardening of the arteries
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One form is the formation of plaque.
•
If coronary arteries become partially blocked and the heart does not receive enough
oxygen, chest pain, called angina pectoris, occurs.
•
If the coronary artery is blocked completely, a heart attack occurs.
•
Angina pectoris—chest pain that occurs when coronary arteries become partially blocked
and the heart cells do not get enough oxygen
•
Diagnosis of a Heart Attack
– More than a million people are admitted to hospitals annually with possible heart
attacks.
– Diagnosing a heart attack is time-consuming and costly.
– Blood levels of the following proteins change during a heart attack:
•
•
Creatine kinase
•
Troponin
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Myoglobin
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Myosin
Repairing Blocked Arteries
– Cardiac catheterization—when a thin tube is threaded from an artery in a leg or
arm up to the coronary arteries to view the blood flow
– Coronary artery bypass surgery—The diseased segment of an artery is cut out and
replaced with a grafted piece of good artery to restore normal flow of blood to the
heart.
– Open-heart surgery—heart is exposed while being repaired and blood is diverted
through a heart–lung machine
– An alternative surgical procedure is percutaneous transluminal coronary
angioplasty (PTCA), in which a balloon is inserted into the artery and inflated so
it pushes the plaque against the wall of the artery, opening the artery.
•
Costs less than bypass surgery, but the blockage recurs many times.
– Alternative to bypass surgery is “stenting,” which involves inserting a catheter
into an artery in the arm or leg, threading it to the blockage point, and inserting
props or “stents” to prop the artery open.
•
Simpler, cheaper, and safer than bypass surgery
– Studies have shown that blockages can be improved through lifestyle changes.
– These costly procedures may not be necessary 100% of the time.
– Most patients look for the quick fix and want surgical intervention.
•
Cardiopulmonary Resuscitation (CPR)
– An emergency procedure administered to a person who has stopped breathing
which involves:
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Mouth-to-mouth breathing
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Repeated compression of the chest
– The rules are now the same for adults and children.
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30 compressions/2 breaths
– Third leading cause of death in the United States after coronary heart disease and
cancer
– High blood pressure is related to at least 70% of all strokes.
– It is a form of cardiovascular disease that affects arteries supplying blood to the
brain.
– Brain cells die within minutes without oxygen.
– A person who has had a stroke can lose the ability to speak, have one arm or leg
become paralyzed, become paralyzed on one side of the body, or die.
– Can occur from injuries to the head or from weak spots in the arteries, called
aneurysms, that balloon and rupture
– Can occur when a weak heart cannot pump enough blood to the brain
– Four kinds of strokes are defined medically.
– Two kinds of stroke are caused by clots that block blood flow to the brain.
•
Cerebral thrombosis and cerebral embolism are the most common types of
stroke; both are caused by clots.
– Two are caused by the rupture and hemorrhage of an artery supplying blood to the
brain.
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Cerebral and subarachnoid hemorrhages are caused by ruptured blood
vessels. These occur less frequently, but have a high fatality rate.
– Signs of a stroke include:
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Sudden weakness or numbness of the face, arm, or leg on one side of the
body
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Sudden dimness or loss of vision, especially in one eye
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Loss of speech, difficulty understanding speech, or trouble talking
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Sudden, severe headaches with no known cause
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Unexplained unsteadiness, dizziness, or fall
– Preventing a Stroke
– Reduce the risk factors that are controllable largely by changes in lifestyle:
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High blood pressure
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Heart disease
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Cigarette smoking
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Transient ischemic attacks
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High red blood cell count
Risk Factors for Cardiovascular Disease
•
Research seems to indicate that plaque begins to build up in the arteries at an early age;
this is why positive lifestyle behaviors are important at all ages.
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Risk Factors
– Smoking
– Overweight and diabetes mellitus
– Hypertension
– Hypercholesterolemia
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Cholesterol
– Cholesterol—There are two major kinds of cholesterol: HDL (“good” cholesterol)
and LDL (“bad” cholesterol).
– Familial hyperlipidemia—A rare inherited disease that results in high levels of
cholesterol in the blood.
– Total cholesterol levels are measured in milligrams per deciliter (mg/dl) of blood.
– Cholesterol level below 200 mg/dl indicates a relatively low risk of coronary heart
disease.
– A level of 240 mg/dl or higher doubles the risk of coronary heart disease (CHD).
– Total cholesterol may not be a reliable indicator because high levels of HDL may
counteract the bad effects of a high LDL count.
– Cholesterol, Statins, and Inflammation
•
Statins are a class of drugs that reduce the level of blood cholesterol.
•
Statins also reduce the level of reactive protein in the blood.
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Statins also reduce inflammation in arteries.
– High Blood Pressure
•
If the cause of high blood pressure (HBP) is unknown, it is referred to as
essential hypertension.
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This includes 90% to 95% of cases of HBP.
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The remaining HBP cases are symptoms of recognizable diseases, such as
kidney abnormality, congenital defect of the aorta, or adrenal gland tumor.
– These types of hypertension are referred to as secondary
hypertension.
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Cholesterol
– Measuring Blood Pressure
– The systolic pressure is the maximum pressure in the arteries that occurs when the
heart contracts.
– The diastolic pressure is the pressure between contractions, when the pressure
falls as blood flows from one chamber to another.
– Normal blood pressure is defined as less than 140/90 (systolic/diastolic).
– Lowering Blood Pressure
– Can be lowered by making the following lifestyle changes:
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Lowering excessive caloric intake
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Increasing physical activity
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Decreasing salt and alcohol consumption
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Consuming adequate amounts of potassium
The Metabolic Syndrome
– Factors that are shared by people at risk for diabetes, CVD, and heart attack:
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Waist circumference larger than 40 inches in men and 35 inches in women
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Serum triglyceride level of 150 mg/dl or greater
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Blood pressure 135/85 or higher
Stress
– The main risk factor for heart disease is stress.
– Type A behavior includes:
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Time urgency, impatience
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Hostility
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Achievement striving
Salt
– There is no scientific evidence that reducing salt intake reduces blood pressure.
Diet and Cardiovascular Disease
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A deficiency of only one nutrient can impair the body’s ability to use all others, even if
the others are present in sufficient amounts.
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Vitamin E: antioxidant in blood and reduces the amount of oxidized LDL that is formed
•
Vitamin C: an antioxidant that can neutralize destructive oxygen atoms and other
oxidizing substances
– 1,000 mg/day is safe
•
Free radicals: compounds in blood that may damage the elastic tissues in arteries that
allow blood vessels to expand and contract
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Beta-carotene: also has antioxidant properties
•
Antioxidant vitamin supplements may not be of much help; get these vitamins from real
food.
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B vitamins: B6, B12, and folic acid lower the levels of homocysteine in the blood.
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Calcium: Deficiency is a risk factor for hypertension in persons of all ages.
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Soy products: Help remove cholesterol from the blood and block oxidation of LDL,
which prevents it from sticking to the walls of arteries.
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Fish oils: Populations that consume large amounts of fish show lower rates of CHD than
populations that do not.
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Trans fats: high levels are found in margarine, and many fast foods. This fat acts the same
as a saturated fat.
•
Tea: Green and black tea contain antioxidant chemicals that help block oxidation of LDL
in the blood.
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Aspirin: Significantly reduces the risk of CHD and heart attacks. Helps “thin” blood and
combats inflammation. If you feel you might be having a heart attack, call 911, and then
take a couple of aspirin to help prevent clotting.
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Alcohol: In one study, men who had one or two drinks a day over 12 years reduced their
risk of dying from a heart attack by about 20% compared with men who did not drink
alcohol.
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Coffee, Tea, and Cocoa
– Moderate coffee intake does not seem to raise CVD risk.
– Polyphenols in tea seem to provide protective cardiovascular effects.
– Flavinoids in unprocessed cocoa seem to increase blood flow and reduce high
blood pressure development.
Preventing Cardiovascular Disease
•
Now that you are armed with knowledge about reducing the chances of heart attacks and
stroke, what needs to be done?
– Reduce weight
– Reduce consumption of foods with saturated fats
– Eat a lot of fruits and vegetables
– Take supplements
– Don’t smoke
– Be active
Cardiovascular Diseases: Understanding Risks and Measures of Prevention
•
Is CVD something that runs in your family?
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What things does your family do that may further that risk?
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What things does your family do that may decrease that risk?
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How will you protect yourself, whether or not your family is at risk for CVD?
Study Guide and Self-Assessments
14.1 My Risk for Heart Disease
Additional Resources
American Heart Association
7272 Greenville Avenue
Dallas, TX 75231
(800) 242-8721 or (214) 748-7212
www.americanheart.org
National Heart, Lung, and Blood Institute
Department of Health and Human Services
Building 31, Room 4A-21
9000 Rockville Pike
Bethesda, MD 20205
(301) 496-4236
http://www.nhlbi.nih.gov