Chapter 2: Preventing Cardiovascular Disease ØCardiovascular disease is the leading cause of death in the U.S.— 42% of all deaths ØApproximately 1.5 million heart attacks occur each year—500,000 are fatal ØAbout 50% of people who have heart attacks wait 2 hours before seeking medical attention

Anatomy of the Heart The heart: ØConsists of cardiac muscle ØWeighs 8 to 10 ounces ØHas two halves (pumps) divided by the septum ØHalves are divided into upper chambers (atria) and lower chambers (ventricles)

Circulation ØThe left side of the heart (systemic pump) receives the oxygenated blood from the lungs and pumps it to all the tissues in the body ØThe right side of the heart (pulmonary pump) receives deoxygenated blood from the body and pumps it to the lungs

Circulation ØThe primary function of circulation is to provide a constant supply of blood and nutrients to cells while removing their waste products ØThe heart has its own conduction system ØThe beating rate and rhythm are established by the sinoatrial (SA) node (pacemaker)

Circulation ØThe electrical contraction pauses at the atrioventricular (AV) node, allowing the ventricles to fill with blood ØThe heart is supplied with blood from coronary circulation after it has been ejected from the heart ØBlood is so important to the heart that every muscle fiber is supplied by at least one capillary

Cardiovascular Disease (1) ØCoronary heart disease (coronary artery disease; CAD) is diagnosed when any artery is narrowed by 60% or more ØA myocardial infarction (heart attack; death of the heart muscle) occurs when blood flow to the heart muscle is disrupted ØMost heart attacks occur after age 65, but the process begins as early as adolescence

Myocardial Infarction ØThe medical term for heart attack is myocardial infarction (MI) ØUp to one third of all heart attacks are silent—without obvious signs or symptoms ØSilent ischemia, reduced blood flow, can initiate heart attacks without warning ØMost heart attacks are obvious

Cardiovascular Disease (2) ØHeart disease is an acquired disease that is preventable ØAmericans as young as 18 have obstructions in their coronary arteries caused by atherosclerosis ØAtherosclerosis, characterized by plaque beneath artery linings, is responsible for 80% of CAD deaths in the U.S.

Brain Attack (Stroke) ØBrain attacks are caused by a thrombus or an embolus (70% to 80%) or a cerebral hemorrhage ØBrain cells die, causing loss of function of some parts of the body ØBrain attacks have the same risk factors and prevention factors as heart disease

Unchangeable Risk Factors for Heart Disease (AHA) ØAge—80% of fatal heart attacks occur after age 65 ØMale gender—Heart disease is the leading cause of death for both males and females »Females have a lower rate than males »Rate is increasing among females, particularly those who smoke and use oral contraceptives ØHeredity and Race—A tendency toward heart disease appears to be hereditary

Changeable Risk Factors Cholesterol (1) ØA certain amount of cholesterol is necessary for good health ØThe best way to lower serum (blood) cholesterol is to reduce intake of saturated fat ØSaturated fat increases the liver’s production of cholesterol

Changeable Risk Factors Cholesterol (2) ØCholesterol is a steroid that does not dissolve in blood, so it is transported to cells by protein packages ØLow-density lipoproteins (LDL), the primary transporters of cholesterol, are the most capable of producing atherosclerosis ØPeople with low blood levels of LDL (less than 100 mg/dl) rarely have heart attacks

Changeable Risk Factors Blood Pressure (1) ØBlood pressure is the force exerted against artery walls as blood travels through the circulatory system ØHigh blood pressure (hypertension) has no signs or symptoms ØAn estimated 90% to 95% of hypertension is essential (of unknown origin) ØHigh BP= 140/90 mmHg

Changeable Risk Factors Blood Pressure (2) ØLong-term uncontrolled hypertension increases the work of the heart, causes it to hypertrophy, and leads to congestive heart failure ØHypertension damages the arteries, accelerates atherosclerosis, and is the most important risk factor for brain attacks

Changeable Risk Factors Tobacco ØCigarette smoking may be the most harmful of the preventable risk factors for chronic illness and premature death ØThese illnesses include chronic bronchitis, emphysema, strokes, and 87% of all lung cancers ØPassive smoking, inhaling the smoke of others, causes the deaths of 38,000 to 43,000 nonsmokers annually

Changeable Risk Factors Physical Inactivity ØPhysical inactivity increases the risk of coronary heart disease by 1.5 to 2.4 times ØThe greatest health benefits are gained when people expend 1500 to 2000 calories (walk 15 to 20 miles) per week ØExercise for health does not have to be as strenuous as exercise for physical fitness

Changeable Risk Factors Physical Inactivity ØPhysical activity is any physical movement that results in energy expenditure—walking, mowing the lawn, vacuuming Ø“Every U.S. adult should accumulate 30 minutes or more of moderate intensity physical activity on most, preferably all, days of the week.” (ACSM/CDC statement)

Changeable Risk Factors Obesity ØObesity contributes to about 300,000 deaths per year ØFat that accumulates in the upper half of the body (central abdominal obesity) is significantly more likely to contribute to heart disease ØA 5% to 10% weight loss that is maintained can significantly reduce the risk of heart disease

Changeable Risk Factors Diabetes Mellitus ØDiabetes is a metabolic disorder in which the body cannot properly use sugar (glucose) as fuel ØType II (90% of all diabetes) occurs in older, overweight, sedentary adults ØDiabetes increases the risk of coronary artery disease 2 to 3 times in men and 3 to 7 times in women

Changeable Risk Factors Stress ØStress elevates heart rate, blood pressure, breathing rate, and blood sugar levels, activates the immune response, and causes other physiological changes ØChronic (long-term) distress significantly strains the body

Prevention of Heart Disease Prevention includes: ØRegular exercise ØOptimal body weight ØSound nutritional practices ØNonuse of tobacco and other drugs ØNonuse or moderate use of alcohol ØDealing constructively with stress ØPeriodic medical examinations

Diagnostic Techniques ØMedical examination and patient history ØExercise stress tests ØThallium treadmill test ØEchocardiography ØCardiac catheterization

Medical Treatment ØLow-dose aspirin therapy ØCoronary artery bypass surgery ØBalloon angioplasty ØCoronary stent ØArtificial valves ØLeft ventricular assist devices ØHeart transplants