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Section 11. Cardiovascular Disorders
Chapter 85. Hypertension
Topic:    Hypertension

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Hypertension

Hypertension is defined as systolic BP >= 140 mm Hg or diastolic BP >= 90 mm Hg. Isolated systolic hypertension, a common form of hypertension in the elderly, is defined as systolic BP >= 140 mm Hg and diastolic BP < 90 mm Hg. For most elderly patients, hypertension does not have a reversible cause and is asymptomatic. Evaluation should include detection of other cardiovascular risk factors and end-organ damage and a search for secondary causes when appropriate. Treatment is with lifestyle modifications and drugs, often starting with a thiazide-type diuretic.

Geriatric Essentials

  • Most people > 65 yr have hypertension. Isolated systolic hypertension (ISH; systolic BP >= 140 mm Hg with diastolic BP < 90 mm Hg) accounts for > 2/3 of cases.
  • ISH is caused primarily by an increase in arterial stiffness due to increased collagen deposition and cross-linking, degeneration of elastin fibers, atherosclerotic changes, and age-related endothelial dysfunction.
  • All elderly people should be screened for hypertension at every health care visit and at least annually.
  • BP readings may be falsely elevated in some elderly patients with very stiff, calcified arteries. This phenomenon is called pseudohypertension.
  • Treatment of hypertension other than ISH reduces incidence of MI, stroke, and heart failure in the elderly.
  • Treatment of ISH when systolic BP is >= 160 mm Hg reduces incidence of MI, stroke, and heart failure. Benefits with treatment of ISH when systolic BP is 140 to 160 mm Hg are presumed but unproven.
  • Most elderly patients ultimately require >= 2 antihypertensive drugs to control BP. Thiazide-type diuretics are especially safe and effective in the elderly.
  • In the elderly, all-cause and cardiovascular mortality rates increase linearly as systolic BP increases. All-cause mortality rates increase when diastolic BP is > 80 mm Hg and < 60 mm Hg (producing a J-shaped curve).

Hypertension is defined as systolic BP >= 140 mm Hg or diastolic BP >= 90 mm Hg. Isolated systolic hypertension (ISH) is defined as systolic BP >= 140 mm Hg and diastolic BP <= 90 mm Hg. These definitions are the same regardless of age. In the US, most people >= 65 yr have hypertension, most commonly ISH. If hypertension has not developed by age 55, the probability of developing it is 90% during a person's lifetime. In developed countries, systolic BP tends to increase gradually with age, while diastolic BP tends to stabilize or decrease after age 55 to 60. The high prevalence of hypertension among elderly people in developed countries might suggest that an age-related increase in arterial pressure is normal, but hypertension is practically nonexistent among elderly people in some developing countries.

When BP is 115/75 to 185/115 mm Hg, each increase of 20 mm Hg in systolic BP or 10 mm Hg in diastolic BP doubles the risk of cardiovascular disease for people between ages 40 and 70. Sequelae of hypertension include coronary artery disease, heart failure, stroke, renal failure, and peripheral vascular disease. People with systolic BP 120 to 139 mm Hg or diastolic BP 80 to 89 mm Hg are also at increased risk of these diseases and are considered to be prehypertensive; such people are candidates for lifestyle modifications to reduce risk. After age 55, high systolic BP conveys a greater risk of cardiovascular disease than high diastolic BP.

Etiology

Ninety percent of people of all ages with hypertension have primary (formerly, essential) hypertension; that is, there is no identifiable cause. The proportion of elderly hypertensive patients with primary hypertension may be lower. Secondary hypertension has a specific cause; these causes, such as an endocrine disorder (eg, Cushing's syndrome, hyperthyroidism, primary aldosteronism, pheochromocytoma), a kidney disorder (eg, polycystic kidney disease, glomerulonephritis, chronic pyelonephritis), or licorice consumption, are uncommon among the elderly; an exception is atherosclerotic renal artery stenosis, which may contribute to high BP in 5 to 10% of elderly patients with hypertension. More often, conditions common among elderly patients may exacerbate primary hypertension or shift prehypertension into the hypertensive range. These conditions include renal insufficiency and failure; use of OTC drugs (eg, pseudoephedrine), prescription drugs (eg, NSAIDs, COX-2 inhibitors, corticosteroids, cyclosporine, tacrolimus, erythropoietin), or herbal remedies (eg, ma huang, yohimbine); excess alcohol use; obesity; hyperthyroidism or hypothyroidism; obstructive sleep apnea; and cancer, via release of humoral pressor substances or via hypercalcemia.

Pathophysiology

The pathophysiology of hypertension in the elderly is complex and usually multifactorial. ISH is caused by an increase in arterial stiffness due to increased collagen deposition and cross-linking, degeneration of elastin fibers, atherosclerotic changes, and age-related endothelial dysfunction. Other possible contributors to hypertension in elderly patients may include genetic factors, classic cardiovascular disease risk factors (eg, tobacco use, diabetes mellitus, obesity, physical inactivity), an imbalance in sympathetic and parasympathetic tone with enhanced vascular reactivity to catechols, vascular remodeling, and renal microvascular changes.

Elevated BP and aging act synergistically to produce nephrosclerosis. Renal blood flow decreases, intrarenal vascular resistance increases, and the GFR and ability to concentrate urine decrease. Nephrosclerosis, combined with an age-related decline in renal function, contributes to the rise in systolic BP with aging.

In most elderly patients, intravascular volume contracts as arterial pressure and total peripheral resistance increase. Plasma renin activity and angiotensin II levels are normal or reduced, suggesting an attenuated relationship between intravascular volume and the renin-angiotensin system. This relationship may explain the enhanced responsiveness to diuretics and Ca channel blockers in many elderly patients with hypertension, particularly those with systolic hypertension.

Symptoms and Signs

For most patients, primary hypertension is asymptomatic, although severe hypertension or an abrupt rise in BP may cause headache, blurred vision, dizziness, or epistaxis. However, in most patients, the presence of symptoms or signs suggests end-organ dysfunction. Cardiac dysfunction is indicated by symptoms of coronary artery disease, heart failure, and arrhythmias, especially atrial fibrillation. Angina pectoris may result from increased myocardial oxygen demand due to left ventricular hypertrophy and increased afterload, even when coronary artery disease is absent. Symptoms and signs of stroke, peripheral arterial disease (eg, intermittent claudication, thoracic aortic dissection, abdominal aortic aneurysm), hypertensive retinopathy, and renal insufficiency or failure may develop.

In elderly patients with secondary hypertension, additional symptoms and signs may be present depending on the cause; however, none are very sensitive or specific.

Diagnosis

Diagnostic evaluation involves documentation of elevated BP, a search for secondary causes, identification of other cardiovascular risk factors that worsen prognosis and influence treatment, and evaluation for end-organ damage.

All elderly people should be screened for hypertension at every health care visit and at least annually. Hypertension is diagnosed when systolic BP is >= 140 mm Hg, diastolic pressure is >= 90 mm Hg, or both. However, before confirming the diagnosis, a high reading should be documented on at least 2 separate occasions with at least 2 separate measurements on each occasion. Hypertension is classified as stage 1 (140 to 159/90 to 99) or stage 2 (>= 160/>= 100--see Table 85-1); the highest level determines stage (eg, 170/80 is stage 2).

Correct measurement technique is especially important for elderly patients. Initially, BP should be measured in both arms (because occlusive atherosclerotic disease of the subclavian or brachial artery may reduce systolic BP in one arm) and with the patient seated (after a 5-min rest). BP should be remeasured 1 and 3 min after the patient stands (to document orthostatic falls in BP, which are common among the elderly, particularly after meals). After differences in BP between arms and between sitting and standing are documented, BP can be measured on the side thought to best reflect true arterial pressure (eg, the higher reading in patients with atherosclerosis, the lower reading in patients with arterial calcification). Two readings from the same site are still advisable, because white-coat hypertension (transient elevations in BP that usually occur early during an office visit) is relatively common among elderly patients. The measurement site chosen should be recorded in the patient's chart for future reference.

Regular BP readings measured outside the clinical setting provide more information than a single office reading. In addition, 24-h ambulatory BP monitoring (ABPM) can determine circadian variations in BP and the percentage of all readings that are abnormal. ABPM may better predict end-organ damage than routine office measurements. ABPM is recommended for patients with sporadically elevated BP readings or white-coat hypertension without evidence of end-organ damage. ABPM is also indicated for patients with poor responses to drugs, hypotensive symptoms during treatment, or autonomic dysfunction.

Pseudohypertension refers to falsely elevated systolic BP readings in elderly patients with very stiff arteries. Pseudohypertension occurs because the BP cuff cannot completely occlude the artery. Osler's sign, the ability to palpate the stiff, thickened radial artery when the sphygmomanometric cuff is inflated to suprasystolic BP, was once thought to suggest pseudohypertension, but more recent studies suggest that Osler's sign is an unreliable marker for this condition. Alternative ways to distinguish true systolic hypertension from pseudohypertension include arm x-rays to document extensive vascular calcification and Doppler flow studies, but neither is routine practice. More commonly, pseudohypertension is diagnosed when elderly patients do not respond to treatment, have markedly elevated systolic BP without signs of end-organ damage, or develop signs of hypotension (eg, fatigue, orthostasis) despite persistently elevated BP measurements.

Secondary hypertension should be suspected when BP is resistant to treatment or increases rapidly over weeks to months or to very high levels. An abdominal bruit over one or both of the renal arteries, especially in a patient with other manifestations of vascular disease, suggests renal artery stenosis. Hypokalemia unrelated to diuretic therapy and accompanied by metabolic alkalosis suggests primary aldosteronism. Other tests for secondary causes of hypertension may include polysomnography (for obstructive sleep apnea), thyroid examination and thyroid function testing (for hyperthyroidism or hypothyroidism), magnetic resonance angiography (for renal artery stenosis [see Photo 85-1]), measurement of 24-h urinary cortisol (for Cushing's syndrome), measurement of plasma metanephrine (for pheochromocytoma), ratio of plasma aldosterone activity to plasma renin activity (for primary aldosteronism), and abdominal CT (for adrenal tumors associated with primary aldosteronism or pheochromocytoma).

Modifiable cardiovascular risk factors that worsen prognosis and that influence treatment include obesity, physical inactivity, diabetes mellitus, tobacco use, and dyslipidemia. Evaluation should therefore include calculation of body mass index (BMI) and measurement of fasting glucose and lipids. Patients should be asked about physical activities and tobacco use.

Evaluation for end-organ damage begins with physical examination. Funduscopic examination provides a glimpse of systemic vascular changes. Advanced hypertensive retinopathy can be distinguished from the changes of arteriosclerosis (eg, increased arteriolar light striping, arteriovenous nicking, tortuosity of blood vessels) by additional changes (eg, arteriolar and venular constriction [see Photo 85-2], hemorrhages [see Photo 85-3], exudates [see Photo 85-4], papilledema [see Photo 85-5]). Retinal changes can be classified into groups with increasingly worse prognostic implications (see Table 85-2).

A complete cardiovascular examination should be performed; it includes a search for diminished peripheral pulses, abdominal palpation for an enlarged pulsatile mass (aortic aneurysm), and auscultation for renal and abdominal bruits.

Testing for end-organ damage should include a urinalysis to detect proteinuria; measurements of BUN and serum creatinine, uric acid, and electrolytes (including Ca); chest x-ray, and ECG (to detect left ventricular hypertrophy, left atrial abnormality, and arrhythmias). More extensive testing (eg, echocardiography) to look for left ventricular hypertrophy or to distinguish systolic from primary diastolic dysfunction is not routinely indicated.

Prognosis

In elderly people, all-cause and cardiovascular mortality rates increase linearly as systolic BP increases. All-cause mortality rates increase when diastolic BP is < 80 mm Hg or < 60 mm Hg.

Treatment

The Seventh Report of the Joint National Committee (JNC 7) provides a guideline for management of hypertension. Overall, JNC 7 recommendations are the same for elderly patients as they are for adults of other ages. Efforts should be made to maintain diastolic BP between 60 mm Hg and 90 mm Hg (between 60 mm Hg and 80 mm Hg if diabetes mellitus or a chronic kidney disorder is present) as long as systolic BP can also be maintained below 140 mm Hg. Although treatment has not been directly shown to reduce mortality rates, treating hypertension reduces incidence of MI by 20 to 25%, stroke by 35 to 40%, and heart failure by up to 50% in patients up to age 90. Treating stage 2 ISH (systolic BP >= 160 mm Hg) reduces incidence of stroke by 30 to 40%, but the effects of treating stage 1 ISH (systolic BP 140 to 159 mm Hg) have not been determined. Nevertheless, indirect evidence generally supports treatment of elderly patients with stage 1 ISH unless the potential for adverse effects from treatment outweighs the benefits. Treatment is similar to that of younger patients and should focus on normalizing systolic BP while maintaining diastolic BP between 60 mm Hg and 90 mm Hg.

Lifestyle modifications are recommended for all patients with systolic BP > 120 mm Hg or diastolic BP > 80 mm Hg. Modifications include smoking cessation; dietary changes, such as the Dietary Approaches to Stop Hypertension (DASH) eating plan (eg, eating a diet rich in fruits, vegetables, and low-fat dairy products with reduced total, saturated, and trans fat intake); and physical activity (eg, aerobic physical activity at least 30 min/day most days of the week) sufficient to maintain BMI at 18.5 to 24.9. Dietary Na intake should be maintained at < 2.4 g/day, and alcohol intake should be limited to 30 mL of ethanol equivalent/day in men or 15 mL in women. These measures help control BP and may enable drug doses to be reduced; they also promote control of other cardiovascular risk factors (eg, diabetes mellitus, dyslipidemia).

If systolic BP is >= 140 mm Hg or DBP is >= 90 mm Hg after adequate lifestyle modifications, most patients without compelling indications should be given a thiazide-type diuretic (see Tables 85-1 and 85-3). Other antihypertensive drugs (ACE inhibitors, beta-blockers, angiotensin II receptor blockers, Ca channel blockers) may be considered (see Tables 85-4, 85-5, 85-6, and 85-7). Direct vasodilators (see Table 85-8) are used rarely and as part of a multidrug regimen.

Patients with certain compelling indications should be given an appropriate drug (see Table 85-9). Other considerations may influence choice of drug. For example, in elderly patients with urinary incontinence, diuretics may worsen bladder control. Men with benign prostatic hyperplasia may obtain dual benefit from alpha1-blockers, although these drugs should not be used as monotherapy because they may increase risk of hospitalization for heart failure. Noncardioselective beta-blockers are relatively contraindicated in patients with peripheral vascular disease or lung disorders.

If the initial dose of an antihypertensive drug does not control BP, the dose may be increased, or a 2nd drug may be added to reduce risk of dose-related adverse effects of the 1st drug. Most elderly patients ultimately require >= 2 antihypertensive drugs. If BP is > 20/10 mm Hg above the goal, combination drug therapy with drugs from 2 classes is indicated; one drug is usually a thiazide-type diuretic.

Overall, adverse effects of antihypertensive drugs are probably no more common among elderly than among younger patients, but the risk of adverse drug-drug interactions is increased because many elderly patients take multiple drugs. In the elderly, loop diuretics may pose a risk of orthostatic hypotension, and centrally acting alpha-agonists are more likely to have CNS effects (eg, depression, forgetfulness, vivid dreams, hallucinations, sleep problems). Thiazides, centrally acting alpha-agonists, and beta-blockers may cause erectile dysfunction in men, and beta-blockers should be used cautiously in patients with a heart rate < 60 beats/min. These effects are not a reason to withhold drug therapy in patients with hypertension, but if the diastolic BP falls to < 60 mm Hg, dose reduction should be considered.

This topic was last updated July 2005.

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