Hypertension is an abnormal elevation in arterial pressure that can be fatal if sustained and untreated. People with hypertension may not display clinical signs or symptoms for many years but eventually can experience symptomatic damage to several target organs, including the kidneys, heart, brain, and eyes. In adults, a sustained systolic blood pressure (BP) of 140 mm Hg or greater or a sustained diastolic blood pressure of 90 mm Hg or greater is defined as hypertension. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) report published in 2003 classifies BP in four stages: normal, prehypertension, stage 1, and stage 2 ( Table 3.1 ). These stages reflect the health risks associated with BPs higher than 115/75 mm Hg and help establish thresholds for treatment and allow for monitoring treatment effectiveness, the latter being important for decreasing the frequency of adverse vascular outcomes associated with chronic high BP such as stroke and myocardial infarction (MI). In contrast, JNC 8 (published in 2014) focuses on evidence-based recommendations for treatment (drug selection) and treatment goals. Together these two documents (JNC 7 and JNC 8) help establish the recommendations for follow-up care of patients based on initial BP measurements (see Table 3.1 ). A separate publication provides similar information on the classification, detection, diagnosis, and management of hypertension in children and adolescents. In children and adolescents, hypertension is defined as elevated BP that persists on repeated measurement at the 95th percentile or greater for age, height, and gender ( Tables 3.2 and 3.3 ). For example, Table 3.3 illustrates that a 6-year-old girl who is at the 50th percentile in height is considered to have hypertension if her BP is persistently 111/74 mm Hg or greater.
| BP Classification | Systolic BP (mm Hg) | Diastolic BP (mm Hg) | Recommended Follow-Up | |
|---|---|---|---|---|
| Normal | <120 | and | <80 | Recheck in 2 years. |
| Prehypertension | 120–139 | or | 80–89 | Recheck in 1 year. |
| Stage 1 hypertension | 140–159 | or | 90–99 | Confirm within 2 months. |
| Stage 2 hypertension | ≥160 | or | ≥100 | Evaluate or refer to source of care within 1 month. For those with higher BP (e.g., >180/110 mm Hg), evaluate and treat immediately or within 1 week, depending on the clinical situation and complications. |
| Classification | SBP or DBP Percentile * |
|---|---|
| Normal | <90th |
| Prehypertension | 90th to <95th, or pressure exceeds 120/80 mm Hg even with <90th percentile up to <95th percentile |
| Stage 1 hypertension | 95th to 99th percentile plus 5 mm Hg |
| Stage 2 hypertension | >99th percentile plus 5 mm Hg |
* For gender, age, and height, as measured on at least three separate occasions.
| Age (yr) | GIRLS’ SBP/DBP (mm Hg) | BOYS’ SBP/DBP (mm Hg) | ||
|---|---|---|---|---|
| 50th Percentile for Height | 75th Percentile for Height | 50th Percentile for Height | 75th Percentile for Height | |
| 1 | 104/58 | 105/59 | 103/56 | 104/57 |
| 6 | 111/74 | 113/74 | 114/74 | 115/75 |
| 12 | 123/80 | 124/81 | 123/81 | 125/82 |
| 17 | 129/84 | 130/85 | 136/87 | 138/87 |
Although only a physician can make the diagnosis of hypertension and decide on its treatment, the JNC guidelines specifically encourage the active participation of all health care professionals in the detection of hypertension and the surveillance of treatment compliance. Accordingly, dental health professionals can play a significant role in the detection and control of hypertension and may be the first to detect a patient with an elevation in BP or with symptoms of hypertensive disease. Along with detection, monitoring is an equally valuable service because patients who are receiving treatment for hypertension may nevertheless fail to achieve adequate control because of poor compliance or inappropriate drug selection or dosing. An abnormal BP reading in the dental office becomes the basis for referral to, or consultation with, a physician. In addition, hypertension poses several considerations with respect to dental management, including monitoring BP during appointments, stress and anxiety reduction, prevention of drug interactions, and awareness and management of adverse drug side effects.
Epidemiology
Hypertension is the most common primary diagnosis in the United States, accounting for 39 million office visits annually. Before 1990, the prevalence of hypertension was steadily declining; however, recent evidence indicates that the trend has reversed, and hypertension is again on the rise. According to National Health and Nutrition Examination Survey (NHANES) data for the period 2011 to 2012, at least 75 million adults in the United States have high blood pressure (HBP) or are taking antihypertensive medication. This estimate equals about 29% of the U.S. population compared with 24% when surveyed between 1988 to 1991. This marked increase is attributed to aging of the population and the epidemic increase in obesity. Accordingly, a typical practice population of 2000 patients will have about 580 patients who have hypertension.
The prevalence of hypertension is similar among men and women but varies with race and ethnicity. The highest prevalence is among non-Hispanic blacks (42%) followed by non-Hispanic whites (28%), Hispanics (26%), and non-Hispanic Asians (25%). Racial and ethnic disparities in prevalence are largely driven by differences in socioeconomic status, environmental influences, and personal behavior and habits.
The prevalence increases with aging, such that more than 65% of Americans aged 60 years and older have hypertension. If people live long enough, more than 90% will develop hypertension. Of note, systolic BP continues to rise throughout life, but diastolic BP rises until around age 50 years and then levels off or falls; as a result, after the age of 50, isolated systolic hypertension becomes the more prevalent pattern. In one study, isolated systolic hypertension was identified in 87% of inadequately controlled patients older than 60 years of age. Isolated diastolic hypertension most commonly is seen before age 50 years. Diastolic BP is a more potent cardiovascular risk factor than is systolic BP until age 50; thereafter, systolic BP is more important.
Awareness of hypertension is important. For this reason, the National High Blood Pressure Education Program was begun in 1972, and its successes are obvious. The number of people with HBP who are aware of their condition has increased over the decades from 51% to 82%, and the percentage of those receiving treatment for HBP has increased from 31% to 76%. The proportion of patients taking medication whose BP is controlled to 140/90 mm Hg has increased from 10% to 52%. Concomitant with increased awareness and treatment has been a significant decline in number of deaths from coronary heart disease (50%) and from stroke (57%), although this decline has slowed in recent years. Although these trends are encouraging, 18% of patients with HBP remain unaware of their disease, 24% of patients with HBP are not being treated, and 48% of hypertensive patients are taking medications but not achieving adequate control of the condition.
Etiology
About 90% of patients have no readily identifiable cause for their disease, which is referred to as primary (essential) hypertension. In the remaining 10% of patients, an underlying cause or condition may be identified; for these patients, the term secondary hypertension is applied. Box 3.1 is a listing of the most common identifiable causes of secondary hypertension. Lifestyle factors (obesity, excessive alcohol intake, excessive dietary sodium and physical inactivity) contribute significantly to the presence, severity and progression of hypertension.
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Chronic kidney disease (e.g., diabetic nephropathy)
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Chronic steroid therapy and Cushing syndrome
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Coarctation of the aorta
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Drug induced or drug related
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Pheochromocytoma
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Primary hyperaldosteronism
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Renovascular disease
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Sleep apnea
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Thyroid or parathyroid disease
Etiology
About 90% of patients have no readily identifiable cause for their disease, which is referred to as primary (essential) hypertension. In the remaining 10% of patients, an underlying cause or condition may be identified; for these patients, the term secondary hypertension is applied. Box 3.1 is a listing of the most common identifiable causes of secondary hypertension. Lifestyle factors (obesity, excessive alcohol intake, excessive dietary sodium and physical inactivity) contribute significantly to the presence, severity and progression of hypertension.
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Chronic kidney disease (e.g., diabetic nephropathy)
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Chronic steroid therapy and Cushing syndrome
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Coarctation of the aorta
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Drug induced or drug related
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Pheochromocytoma
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Primary hyperaldosteronism
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Renovascular disease
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Sleep apnea
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Thyroid or parathyroid disease
Pathophysiology and Complications
In primary hypertension, the basic underlying defect is a failure in the regulation of vascular resistance. The pulsating force is modified by the degree of elasticity of the walls of larger arteries and the resistance of the arteriolar bed. Control of vascular resistance is multifactorial, and abnormalities may exist in one or more areas. Mechanisms of control include neural baroreflexes and ongoing maintenance of sympathetic vasomotor tone and other effects mediated by neurotransmitters such as norepinephrine, extracellular fluid, and sodium stores; the renin–angiotensin–aldosterone pressor system; and locally active hormones and substances such as prostaglandins, kinins, adenosine, and hydrogen ions (H+). In our modern cultures, high salt intake appears to trigger neuromodulatory signals that activate the sympathetic nervous system, resulting in increased renin secretion by the kidneys. In isolated systolic hypertension, which commonly is seen in older adults, the underlying problem is one of central arterial stiffness and loss of elasticity.
Several physiologic factors may have an effect on BP. Increased viscosity of the blood (e.g., polycythemia) may cause an elevation in BP resulting from an increase in resistance to flow. A decrease in blood volume or tissue fluid volume (e.g., anemia, hemorrhage) reduces BP. Conversely, an increase in blood volume or tissue fluid volume (e.g., sodium and fluid retention) increases BP. Increases in cardiac output associated with exercise, fever, or thyrotoxicosis can increase BP. In addition, BP demonstrates a circadian variation with highest levels seen in early to mid-morning, lower levels as the day progresses, and the lowest BP at night.
A linear relationship exists between BPs at any level above normal and an increase in morbidity and mortality rates from stroke and coronary heart disease. BPs above 115 mm Hg systolic and 75 mm Hg diastolic are associated with increased risk of cardiovascular disease. It is estimated that about 15% of all BP-related deaths from coronary heart disease occur in persons with BP in the prehypertensive range. However, the higher the BP, the greater the chances of heart attack, heart failure, stroke, and kidney disease. For every increase in BP of 20 mm Hg systolic and 10 mm Hg diastolic, a doubling of mortality related to ischemic heart disease and stroke occurs. Hypertension precedes the onset of vascular changes in the kidney, heart, brain, and retina that lead to such clinical complications as renal failure, stroke, coronary insufficiency, MI, congestive heart failure, dementia, encephalopathy, and blindness. If the condition goes untreated, a significant number of persons die prematurely. About 50% of hypertensive patients die of coronary heart disease or congestive heart failure, about 33% of stroke, and about 10% of renal failure.
Clinical Presentation
Signs and Symptoms
Hypertension may remain an asymptomatic disease for many years, with the only sign being an elevated BP. BP is measured with the use of a sphygmomanometer ( Fig. 3.1 ). Pressure at the peak of ventricular contraction is the systolic pressure. Diastolic pressure represents the total resting resistance in the arterial system after passage of the pulsating force produced by contraction of the left ventricle. The difference between diastolic and systolic pressures is called pulse pressure. Mean arterial pressure is roughly defined as the sum of the diastolic pressure plus one third the pulse pressure. Patients commonly are found to have variability in BP throughout the day and according to their environment. About 20% of patients with untreated stage 1 hypertension have what is called white coat hypertension, which is defined as consistently elevated BP only in the presence of a health care worker but not elsewhere. In these patients, accurate BP readings may require self-measurement at home or 24-hour ambulatory monitoring. Persons with BP elevation in this setting are at lower risk for hypertensive complications than are those with sustained hypertension.
Before the age of 50 years, hypertension typically is characterized by an elevation in both diastolic and systolic pressures. Isolated diastolic hypertension, defined as a systolic BP of 140 or less and a diastolic BP of 90 or greater, is uncommon and most often is found in younger adults. Although the prognostic significance of this condition remains unclear and controversial, it appears that it may be relatively benign. Isolated systolic hypertension is defined as a systolic pressure of 140 mm Hg or higher and a diastolic BP of 90 mm Hg or less; it generally is found in older patients and constitutes an important risk factor for cardiovascular disease. Occasionally, isolated systolic BP elevation is found in older children and young adults, often male. In these age groups, this form of hypertension is due to the combination of rapid growth in height and very elastic arteries, which accentuate the normal amplification of the pressure wave between the aorta and the brachial artery, resulting in high systolic pressure in the brachial artery but normal systolic pressure in the aorta.
The earliest sign of hypertension is an elevated BP reading; however, funduscopic examination of the retina may show early changes of hypertension consisting of narrowed arterioles with sclerosis. As indicated earlier, hypertension may remain an asymptomatic disease for many years, but when symptoms do occur, they can include headache, tinnitus, and dizziness. These symptoms are not specific for hypertension and may be experienced just as commonly by normotensive persons.
Late signs and symptoms are related to involvement of various target organs, including the kidneys, brain, heart, or eyes ( Box 3.2 ). In advanced cases, blurred vision caused by retinal vessel hemorrhage, exudate, and papilledema may occur. These eye findings are indicative of accelerated malignant hypertension, a medical emergency that requires immediate intervention. Hypertensive encephalopathy is characterized by headache, irritability, alterations in consciousness, and other signs of central nervous system (CNS) dysfunction. Other findings in advanced cases may include enlargement of the left ventricle with impairment of cardiac function, leading to congestive heart failure. Renal involvement can result in hematuria, proteinuria, and renal failure. Persons with hypertension may report fatigue and coldness in the legs or claudication resulting from the peripheral arterial changes that may occur in advanced hypertension. Patients with hypertension often demonstrate an accelerated cognitive decline with aging. Although these changes may be seen in patients with both primary and secondary hypertension, additional signs or symptoms may be present in secondary hypertension associated with underlying disease.
Early
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Elevated blood pressure readings
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Narrowing and sclerosis of retinal arterioles
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Headache
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Dizziness
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Tinnitus
Advanced
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Rupture and hemorrhage of retinal arterioles
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Papilledema
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Left ventricular hypertrophy
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Proteinuria
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Congestive heart failure
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Angina pectoris
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Renal failure
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Dementia
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Encephalopathy
Laboratory and Diagnostic Findings
Current JNC 7 and 8 guidelines recommend that patients who have sustained hypertension be screened through routine laboratory tests, including 12-lead electrocardiography (ECG), urinalysis, blood glucose, hematocrit, electrolytes, creatinine, calcium, and lipid profile. Results of these tests serve as baseline laboratory values that the physician should obtain before initiating therapy. Additional tests that assess thyroid function and serum aldosterone should be considered if clinical and laboratory findings suggest the presence of an underlying cause for hypertension.
Medical Management
Evaluation of a patient with hypertension includes a thorough medical history, a complete physical examination, and routine laboratory tests as described earlier. Additional diagnostic tests or procedures may be performed to detect secondary causes of hypertension or to make a definitive diagnosis. Patients found to have an identifiable cause for their hypertension should be treated for that disorder and may require a referral to a nephrologist or endocrinologist. Those without an identifiable cause are diagnosed with primary hypertension.
Classification and diagnosis of BP (see Table 3.1 ) are based on an average of two or more properly measured BP readings obtained in the seated patient on each of two or more office visits. Measurement of BP has been traditionally achieved using the auscultatory method with a manual aneroid (with a dial) or hybrid sphygmomanometer. Electronic automated devices are now commonly used (see Fig. 3.1 ). In a patient who has been quietly seated for 5 minutes, the appropriate sized cuff is placed around the upper arm, at the vertical height of the heart, and the cuff is inflated to obtain a proper reading (see Chapter 1 ). Clinicians should realize that BP varies throughout the day, and accurate measurements are important for achieving the proper diagnosis and treatment.
Patients with a diagnosis of prehypertension are not usually candidates for drug therapy but rather are encouraged to adopt lifestyle modifications to decrease their risk of developing the disease. Prehypertension is not a disease but rather a designation that reflects the fact that these patients are at increased risk for the development of hypertension. Lifestyle modifications include losing weight; adopting a diet rich in vegetables, fruits, and low-fat dairy products; reducing intake of foods high in cholesterol and saturated fats; decreasing sodium intake; limiting alcohol intake; quitting smoking; and engaging in daily aerobic physical activity ( Box 3.3 ). Patients with prehypertension, as well as those with diagnosed hypertension, are strongly encouraged to follow these recommendations because lifestyle modifications have been shown to effectively reduce BP, prevent or delay the incidence of hypertension, enhance antihypertensive drug therapy, and decrease cardiovascular risk. If lifestyle modifications are found to be inadequate for achieving desired BP reduction, drug therapy is initiated.
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Weight loss
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DASH (Dietary Approaches to Stop Hypertension) diet: fruits, vegetables, low-fat dairy products
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Reduced intake of cholesterol-rich foods
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Reduced intake of saturated and total fats
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Reduced sodium intake to <2.4 g/day
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Regular aerobic physical activity on most days (30 minutes of brisk walking)
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Quit smoking
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Limited alcohol intake to no more than 1 oz/day (2 drinks for men and 1 drink for women)
Pharmacologic management of hypertension is guided by two recent publications from JNC 8 and the American Society of Hypertension (ASH) and the International Society of Hypertension (IHS). Current guidelines suggest that all people with hypertension—stages 1 and 2—should be treated. JNC 8 recommends drug treatment should be initiated for persons younger than age 60 years when the BP is greater than 140/90 mm Hg, to a goal of less than 140/90 mm Hg. The ASH/ISH and the Canadian Hypertension Education Program guidelines recommend a goal of less than 140/90 mm Hg up to age 80 years. For older adults (aged 60 years and older or 80 years and older ) the goal is to lower BP to less than 150/90 mm Hg. The ASH/ISH also recommends a goal of less than 130/80 mm Hg for patients with chronic kidney disease who have albuminuria. Although meta-analysis studies show that cardiovascular benefits can be achieved from more intensive BP lowering (i.e., levels <140/90) in high-risk groups, it may take a few years for the national guidelines to be adjusted to reflect these data.
Many drugs are currently available to treat patients with hypertension ( Table 3.4 ). JNC 8 recommends diuretics, angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), and calcium channel blockers (CCBs) as first-line choices for the general nonblack population. For the general black population, a thiazide diuretic or CCB is recommended as initial therapy. Other drugs used as secondary choices include beta-blockers, α 1 -adrenergic blockers, and central α 2 agonists, as well as other centrally acting drugs and direct vasodilators. Fig. 3.2 depicts the algorithm suggested by the JNC 8 for the treatment of hypertension. For early stage 1 hypertension, single-drug therapy may be effective; however, for later stage 1 and for stage 2 hypertension, two or more drug combinations are necessary. The presence of certain comorbid conditions or factors such as heart failure, previous MI, diabetes, or kidney disease may be a compelling reason to select specific drugs or classes of drugs that have been found to be beneficial in clinical trials. Of note, aggressive pharmacologic treatment of hypertension has clear benefits. In clinical trials, antihypertensive therapy resulted in an average reduction in stroke incidence of 35% to 40%; MI, 20% to 25%; and heart failure, greater than 50%.
