Cardiovascular Function



Cardiovascular Function


Barbara D. Powe, PhD, RN




Heart disease is the leading cause of death in the United States and is a major cause of disability. Coronary heart disease is the principal type of heart disease. According to the Centers for Disease Control and Prevention (CDC), 652,091 people die of heart disease in the United States each year, which is about 27% of all U.S. deaths (2009). In 2009, heart disease was projected to cost more than $304.6 billion, including health care services, medications, and lost productivity (Statistics Committee and Stroke Statistics Subcommittee, 2009). Risk factors for cardiovascular disease include high cholesterol levels, hypertension, diabetes mellitus, tobacco use, physical inactivity, obesity, alcohol use, age, and heredity (CDC, 2009). As an individual ages, the chances of comorbid conditions increase. The reality is that atherosclerosis, the underlying cause of the majority of clinical cardiovascular problems, is typically present for years before the onset of a clinical event such as a heart attack or symptoms such as angina manifest themselves (Statistics Committee and Stroke Statistics Subcommittee, 2009).


This chapter examines the age-related changes and common problems and conditions of the cardiovascular system that affect older adults.



Age-Related Changes in Structure and Function


Aging alters the cardiovascular system both structurally and physiologically. However, there is increasing evidence that lifestyle and diet can modify some of these age-related changes (Beers & Berkow, 2000; Deaton, Bennett, & Riegel, 2004; Ferebee, 2006). As people age, changes occur within the heart. For example, the heart rate decreases, the left ventricular wall thickens and results in an overall increase in oxygen demand, and there is increased collagen and decreased elastin in the heart muscle and vessel walls (Banasik, 2010b; Beers & Berkow, 2000; Blach, 2006; McCance & Huether, 2006; Morton, Fontaine, Hudak, & Gallo, 2005). The size of the left atrium increases, and aortic distensibility and vascular tone decrease. These changes decrease myocardial muscle contraction and thus cardiac output and cardiac reserve. Decreases occur in diastolic pressure, diastolic filling, and beta-adrenergic stimulation; increases occur in arterial pressure, systolic pressure, wave velocity, and left ventricular end diastolic pressure; and the muscle contraction, muscle relaxation, and ventricle relaxation phases are elongated (Banasik, 2010b; Beers & Berkow, 2000; Larsen, 2009). An S4 heart sound commonly occurs in older adults (McCance & Huether, 2006), and about 50% of older adults have a grade 1 or 2 systolic murmur (Jett, 2008).




Vessels


Calcification of vessels occurs, making them tortuous. The elastin in the vessel wall decreases, which causes thickening and rigidity, especially in the coronary arteries (Seidel, Ball, Dains, & Benedict, 2006). This increases the risk of atherosclerotic buildup, especially in those individuals with adverse lifestyle practices. Systolic blood pressure (SBP) is increased in older adults because of a loss of arterial distensibility due to arterial stiffening (Emerson & Lungstrom, 2010). The diastolic blood pressure (DBP) remains the same or may be elevated slightly; thus the pulse pressure widens. Older adults are less sensitive to the baroreceptor regulation of blood pressure. This causes fluctuations in blood pressure and contributes to increased SBP. Isolated systolic hypertension (ISH) is common in the older adult population.




Common Cardiovascular Problems


Cardiovascular disease (CVD) is the leading cause of death for both men and women in the United States, although women tend to be older when their CVD becomes apparent (Banasik, 2010a). In addition, CVD accounts for more hospital admissions than any other disease or condition. About half of the hospitalizations are attributed to coronary heart disease (CHD, also referred to as ischemic heart disease), and conditions such as strokes, hypertension, heart failure, arrhythmias (particularly heart blockage), valvular conditions, and peripheral vascular disease (PVD) account for other cardiovascular diseases (Banasik, 2010a).


The aging process varies among individuals, which may be attributed to factors of heredity. In addition, the effects of advancing age on cardiovascular structure and function are influenced by the presence of noncardiovascular disease and variations in lifestyle. It may not always be clear which changes in the cardiovascular system are from the normal aging process and which are caused by lifestyle (Banasik, 2010a). Many forms of CVD can be accelerated by unhealthy lifestyle choices such as smoking, physical inactivity, high-risk dietary behaviors, obesity, stress, and hormonal use by women. Chronic diseases such as hypertension and diabetes mellitus also play a role in accelerating changes.



Contributing Factors to Heart Disease


Risk factors are classified as nonmodifiable and modifiable (Box 23–1). Age, gender, and family history are risk factors that cannot be modified. Smoking, high blood pressure, a high-fat diet, obesity, physical inactivity, and stress are amenable to change. Research has demonstrated that the adoption of a healthier lifestyle has the potential to reduce or prevent the incidence of morbidity and death from ischemic heart disease and stroke. Health promotion and disease prevention are discussed in Chapter 8.




Blood Pressure


High blood pressure, or hypertension, is a major modifiable risk factor that contributes to the incidence of coronary artery disease (CAD) and stroke. It also contributes to the development of congestive heart failure (CHF), renal failure, and PVD. It is estimated that one in three adults have high blood pressure. Data collected by the National Center for Health Statistics in the 2005 to 2006 survey showed that 29% of all Americans had hypertension (Ostchega, Yoon, Hughes, & Louis, 2008). During this same period, an additional 28% of U.S. adults had prehypertension and were not being treated (Ostchega et al, 2008). Almost one fifth (21.3%) of people with high blood pressure do not know they have it, and it is more prevalent among blacks than whites (CDC, 2007; Ostchega et al, 2008). Lowering blood pressure by changes in lifestyle or by medication can lower the risk of heart disease and heart attack (CDC, 2007).


There is a 90% lifetime risk of hypertension for people with normotensive ranges at age 55 (Joint National Committee [JNC 7], 2003). ISH, in which the SBP is 140 mm Hg or higher while the DBP is 90 mm Hg or more, is the predominate subtype of hypertension in persons aged 55 years or older (Emerson, 2010). This has changed the theory of treating older persons more cautiously for hypertension; they should receive the same treatment as others to prevent complications.



Diet


An elevated serum cholesterol level is a major risk factor for coronary heart disease in both men and women. A total cholesterol level of 150 mg/dL is where atherosclerosis begins to accelerate. The age-adjusted mean serum cholesterol levels among adults aged 20 to 74 years declined from 222 mg/dL in 1960 to 1962 to 204 mg/dL in 1999 to 2002 and further declined to 199 mg/dL in 2005 to 2006 (Schober, Carroll, Lacher, & Hirsch, 2007). However, in 2005 to 2006, 16% of adults had serum cholesterol levels of 240 mg/dL or greater. A cholesterol level below 200 mg/dL is optimum. A woman’s chance of experiencing a recurrent myocardial infarction (MI) is nine times greater with a cholesterol level of 275 mg/dL or higher than with a cholesterol level below 200 mg/dL. The serum levels of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) are also important to monitor. LDL carries cholesterol to the walls of the arteries (a positive risk factor), and HDL represents the cholesterol being carried from the cells (a negative risk factor). In the average man, HDL cholesterol levels range from 40 to 50 mg/dL. In the average woman, they range from 50 to 60 mg/dL. An HDL cholesterol level of 60 mg/dL or higher is believed to provide some protection against heart disease (American Heart Association [AHA], 2008). Lower levels of LDL cholesterol are equated with lower risk of heart attack and stroke. An optimal level for LDL is less than 100mg/dL, whereas a range of 100 to 129mg/dL is considered a near optimal range (AHA, 2008).


Decreasing fat content in the diet is the first step in reducing cholesterol levels. The AHA recommends reducing the risk of cardiovascular disease by limiting the intake of saturated fat to less than 7% of energy, trans fat to less than 1% of energy, and cholesterol to less than 300 mg/day (Lichtenstein et al, 2006). Research supports the fact that older persons can make and sustain lifestyle changes. Because of the increased risk of cardiovascular disease in the elderly, even seemingly small improvements in risk factors (e.g., small reductions in blood pressure and LDL cholesterol level through diet and lifestyle changes) would be of great benefit. However, the AHA warns that because older individuals have decreased energy needs while their vitamin and mineral requirements remain constant or increase, they should be counseled to select nutrient-dense choices within each food group (Lichtenstein et al, 2006).



Smoking


Smoking continues to be a major risk factor in the development of heart disease. Although a decline has been seen in the use of tobacco largely as a result of health promotion campaigns, clean air environments, and peer pressure, smoking continues to be a major risk factor for heart disease in the United States. Cigarette smoking doubles an individual’s risk of stroke, and smokers are two to four times more likely to develop CHD than nonsmokers (CDC, 2008). Smoking increases platelet aggregation and causes coronary artery spasms. Nicotine increases blood pressure and cardiac demands. Carbon monoxide in tobacco smoke decreases the oxygen-carrying capacity of the blood. Smoking is a significant cardiac risk factor.


Smoking a few cigarettes a day greatly increases cardiac risk. Smoking cessation decreases the risk of MI. After 10 years of abstinence, an individual’s risk is the same as that of a nonsmoker. Smoking cessation should be encouraged at every encounter. The Agency for Health Care Policy and Research has established recommendations for smoking cessation (see Chapter 24 for smoking cessation information).



Physical Activity


A sedentary lifestyle is another modifiable cardiac risk factor. The AHA recommends 30 minutes of moderate-intensity exercise four or five times a week (Lichtenstein et al, 2006). Health care professionals should encourage clients to exercise and promote ways to increase activity with daily routines, such as parking the car a little farther from the store, using the stairs to go up or down one floor, or walking to the post office if it is close enough. It is recommended that anyone beginning an exercise program should first consult a physician for guidelines.


Older adults should begin an exercise program with a 10-to 15-minute warm-up to achieve 75% of their maximum heart rate safely. Too many people want to progress too quickly, which increases their chance for injuries. Walking is the best aerobic exercise for older adults. They can set their own pace, decide the location, and avoid injuries. When beginning an exercise program, older adults should start with 5 to 10 minutes two or three times a week and gradually increase to the recommended 30 minutes four or five times a week (Lichtenstein et al, 2006).



Obesity


Obesity is another modifiable cardiac risk factor. Obesity is usually associated with a sedentary lifestyle and a high-fat diet, which add to the individual’s cardiac risk profile. A healthy body weight is currently defined as a body mass index (BMI) of 18.5 to 24.9 kg/m2. Overweight is a BMI between 25 and 29.9 kg/m2, and obesity is a BMI ≥ 30 kg/m2. Currently, about one third of adults are overweight, and an additional one third are obese (Lichtenstein et al, 2006; Roberts & Barnard, 2005) The National Health and Nutrition Examination Survey (NHANES) III (2006) data show that more than 65 million Americans have a BMI of more than 25. BMI is calculated in kilograms per meter squared. Excess body weight increases cardiovascular risk factors (e.g., by increasing LDL, blood pressure, and blood glucose levels and by reducing HDL levels).




Stress


At one time, stress was thought to be associated with the type A behavior of the goal- and task-oriented high achiever. This belief is now being modified, and researchers are examining the individual’s adaptation to stress from other perspectives, such as anger control and the support of family, friends, and significant others, and the means by which individuals cope with stress.


There are many ways of decreasing stress, and much literature is available on the topic. Yoga, meditation, relaxation tapes, visualization, and physical activity are a few of the methods used. It is imperative that research continue to examine the effects of stress on those age 65 or older and that nurses examine factors in the client’s environment that are amenable to change. For example, an older client may not be able to prepare meals because of physical limitations or safety reasons. Referral to a Meals on Wheels program or a community-based program in which individuals share meals is just one example of simple modification. Older individuals living in an apartment, sharing their meals, and dividing tasks of shopping, meal preparation, and clean-up are other popular concepts. This way, older clients can maintain balanced diets and enjoy the companionship of peers.




Hypertension


Hypertension has been termed the silent killer because much of the population with high blood pressure is unaware of having this condition, despite the availability of advanced screening programs. The detection and treatment of hypertension have increased over the years. In spite of this, the incidence of complications of hypertension has not decreased. These complications include stroke, end-stage renal failure, and heart failure (Ostchega et al, 2008).


Prevention of hypertension is a realistic goal, based on improving the average blood pressure in the general population. The tools available to accomplish this lifesaving goal are



EVIDENCE-BASED PRACTICE


Repetition in Patient Teaching is Beneficial






From Blank FS, Smithline HA: Evaluation of an educational video for cardiac patients, Clin Nurs Res 11(4):403, 2002.


contained in a large body of evidence, which has increased greatly in the past two decades and implicates key aspects of modern lifestyle in the epidemic of hypertension. Adoption of a healthier lifestyle, starting in childhood and youth, can prevent and reverse abnormal blood pressure patterns.


Hypertension is the most commonplace CVD in the United States today. Blood pressure and pulse pressure increase progressively with age. According to Framingham data, adults at age 55 with normal blood pressures have an estimated 90% lifetime risk for developing hypertension (Vasan, 2002; JNC, 2003). Blood pressure screening must be done during every health care encounter with an older adult to detect hypertension and prevent its complications.


Hypertension stage 1 is classified as an SBP of 140 to 159 mm Hg and a DBP of 90 to 99 mm Hg; it indicates the necessity of taking antihypertensive medications. The diagnosis is made after at least two subsequent visits after the initial visit. Blood pressure is measured with the client supine or sitting and then standing (except for those clients whose SBP is greater than 210 mm Hg and DBP is greater than 120 mm Hg; these individuals are deemed to have high blood pressure after one visit). The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure provides new guidelines for hypertension prevention and management. These findings are summarized below (JNC, 2003).



• In persons older than 50 years, SBP greater than 140 mm Hg is a much more important CVD risk factor than diastolic blood pressure.


• The risk of CVD beginning at 115/75 mm Hg doubles with each increment of 20/10 mm Hg.


• Individuals with an SBP of 120 to 139 mm Hg or a DBP of 80 to 89 mm Hg should be considered as prehypertensive and require health-promoting lifestyle modifications to prevent CVD.


• Thiazide-type diuretics should be the drugs used for treatment in most patients with uncomplicated hypertension, either alone or combined with drugs from other classes. Certain high-risk conditions are compelling indications for the initial use of other antihypertensive drug classes (e.g., angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta-blockers, and calcium channel blockers).


• Most patients with hypertension will require two or more antihypertensive medications to achieve their goal blood pressure (<140/90 mm Hg or <130/80 mm Hg for patients with diabetes or chronic kidney disease).


• If blood pressure is >20/10 mm Hg above the goal blood pressure, consideration should be given to initiating therapy with two agents, one of which usually should be a thiazide-type diuretic.


ISH is more common in older adults, as SBP rises disproportionately to DBP because of increased arterial stiffness and rigidity. In the past, it was argued that hypertension was a normal process of aging and did not require therapy. However, data from the Framingham Heart Study confirm that cardiovascular risk escalates dramatically in older adults. The addition of risk factors such as smoking, glucose intolerance, hypercholesterolemia, and left ventricular hypertrophy significantly elevates risk.


The phenomenon of pseudohypertension, that is, falsely elevated blood pressure, is found in the older adult population. Pseudohypertension is a result of the calcification and thickening of the arterial wall. Rigidity in the brachial artery leads to ineffective compression of the brachial artery with a sphygmomanometer. Pseudohypertension may be suspected without evidence of target organ damage despite elevated blood pressure readings or if hypotensive symptoms develop with therapy while blood pressure readings remain high. Osler’s maneuver is a screening test for pseudohypertension. It is performed by palpating the brachial or radial artery after inflating the sphygmomanometer above the systolic pressure. A positive Osler’s test reveals a palpable pulse (Lookinland & Beckstrand, 2003).


Hypertension has been classified into two types: primary and secondary. Primary hypertension is the most common form. Although the exact cause is unknown, the contributing factors are family history, age, race, diet (e.g., foods high in saturated fats and salt or decreased potassium, magnesium, and calcium intake), smoking, stress, alcohol and drug consumption, lack of physical activity, and hormonal intake.


Secondary hypertension refers to elevated blood pressure caused by underlying disease such as renal artery disease, renal parenchymal disorders, endocrine and metabolic disorders, central nervous system (CNS) disorders, coarctation of the aorta, and increased intravascular volume.


All prescription and over-the-counter medications need to be assessed for possible causes of elevated blood pressure. Drug-induced hypertension has occurred with the administration of amphetamines and glucocorticoids. Decongestants, phenobarbital, rifampin, and nonsteroidal antiinflammatory drugs (NSAIDs) may adversely affect the action of some medications for hypertension. NSAIDs have been found to cause elevated blood pressure in normotensive older adults (Tucker, 2003). Many older adults are taking NSAIDs for various musculoskeletal problems. These individuals should have their blood pressure closely monitored.


A positive correlation exists between obesity and high blood pressure. Advancing age is associated with a loss of lean body mass and an increase in adipose tissue. Excess fat in the upper body or a waist circumference of 35 inches or greater in women or 40 inches or greater in men increases the risk for hypertension. Metabolic syndrome includes abdominal obesity, glucose intolerance, high triglyceride levels, and low HDL levels. A 10% reduction of total weight will decrease blood pressure in many overweight individuals. This factor has significance because it underscores the importance of weight reduction in the older adult population (JNC, 2003).


Research data have correlated increased sodium intake and high blood pressure. It has been shown that a reduction in sodium to 100 mmol/day may reduce SBP by 2 to 8 mm Hg. The Dietary Approach to Stop Hypertension (DASH) diet can reduce SBP by 8 to 14 mm Hg. These results were higher in older adults and those with increased blood pressure (JNC, 2003).


The pathophysiology of hypertension is complex because various environmental, structural, renal, hormonal, and homeostatic mechanisms contribute to blood pressure maintenance, especially in the aging population. A detailed description of the mechanisms involved is outside the scope of this text.


Hypertension has been associated with arteriolar thickening, vascular smooth muscle constriction, and elevated vascular resistance. With age, peripheral vascular resistance increases significantly. It is also possible that functional alterations in the vascular smooth muscle contribute to these changes. The alpha-adrenergic responsiveness of the vascular smooth muscle does not change with age; however, the beta-adrenergic responsiveness declines with age with a consequent decrease in the relaxation of the vascular smooth muscle. There also appears to be increased renal vascular resistance and decreased renal blood flow. Left ventricular hypertrophy occurs as an adaptation to long-standing hypertension and may lead to CHF. Once this occurs, there is a significant increase in cardiovascular risk, particularly for ventricular arrhythmia and sudden death.


In mild to moderate hypertension the client may be asymptomatic. As the disease progresses, the client may experience fatigue, dizziness, headaches, vertigo, and palpitations. In severe hypertension the client may experience throbbing occipital headaches, confusion, visual loss, focal deficits, epistaxis, and coma.


It is imperative that the practitioner assess for other target organ damage and symptoms. Hypertension may lead to damage in various organs, resulting in the following conditions:



The diagnostic tests and procedures search for secondary causes of hypertension and assess for end-target organ damage. In assessments for comorbidity, older adults are likely to have coexisting cardiac, vascular, and renal disease.


The health care provider should obtain a history regarding lifestyle factors and should conduct an in-depth physical examination. The following tests should be included: hemoglobin and hematocrit to exclude anemia or polycythemia; urinalysis to investigate for proteinuria or other signs of renal failure; serum sodium, potassium, and creatinine levels; fasting plasma glucose level to determine whether antihypertensive therapy may be affecting diabetes mellitus, a cardiac risk factor; serum total cholesterol and HDL levels to assess for hyperlipidemia; ECG; chest x-ray study; and possibly, echocardiogram to assess left ventricular function and hypertrophy.


The physical examination should include examination of the neck (to detect carotid bruits, jugular vein distention, or an enlarged thyroid), the heart (to detect abnormalities in rate and rhythm, heaves, lifts, murmurs, and third or fourth heart sounds), the lungs (to detect rales), the abdomen (to detect bruits, masses, and aortic pulsations), and the extremities (to detect peripheral pulses and edema).



Pharmacologic Treatment


One of the most important considerations in drug therapy in older adults is that blood pressure should be lowered gradually, beginning with low doses of a single agent. The various steps involved in the treatment of blood pressure are



The general principles for managing high blood pressure in older clients include the following:



• The goal of treatment is a blood pressure less than 120/80 mm Hg. For those with significant systolic hypertension, an interim goal of less than 160/90 mm Hg may be necessary. The results of the Hypertensive Optimal Treatment Study were released after the JNC’s Seventh Report on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC, 2003).


• ISH (SBP over 160 mm Hg and DBP of 85 to 90 mm Hg) should be treated.


• Older adults are more likely to experience an orthostatic drop in blood pressure than younger adults. Blood pressure should always be taken with the client both sitting and standing.


• When pharmacologic therapy is used, the initial daily dose should be half that recommended for middle-aged adults.


• Thiazide diuretics or beta-blockers in combination with a thiazide (e.g., atenolol [Tenormin] with hydrochlorothiazide) are recommended because they decrease morbidity and mortality.


• Diuretics are preferred for ISH.


• The choice of an alternative first- or second-step drug should be based on the client’s individual characteristics.


• After blood pressure has been controlled for 1 year, the dosage of the drug should be stepped down, if possible.


The use of antihypertensive drugs has been shown to be effective and well tolerated in older adults. The prescription is “to proceed slowly and with caution” and to monitor for adverse reactions. If this principle is adhered to, older adults can be treated with minimal side effects. Table 23–1 provides the classifications of antihypertensive drugs, their adverse effects, and the nursing implications.



TABLE 23–1


CLASSIFICATION OF ANTIHYPERTENSIVE DRUGS, ADVERSE EFFECTS, AND NURSING IMPLICATIONS

































ANTIHYPERTENSIVE DRUG ADVERSE EFFECTS NURSING IMPLICATIONS
Diuretics
Thiazides



Loop Diuretics



Potassium-Sparing Diuretics



Aldosterone Receptor Blockers

Nov 26, 2016 | Posted by in NURSING | Comments Off on Cardiovascular Function
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