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Until the mid-20th century, clinicians' concern was directed mainly to the systolic component of blood pressure.Later, however, when systolic blood pressure was found to be elevated with advancing age and decreased compliance of the arterial wall,it began to be considered an inevitable consequence of aging.Based on this belief, physicians often concluded that only the diastolic blood pressure elevation, which reflected peripheral vascular resistance,was harmful, while systolic hypertension was innocuous.Therapeutic intervention was practiced mainly for diastolic hypertension, and research protocols were based on the levels of diastolic blood pressure alone.In the 1950s, even when life insurance companies' actuarial data revealed that systolic and diastolic blood pressure elevations were hazardous to health,few clinicians took heed. In 1962, the World Health Organization also defined hypertensionas a blood pressure level of 165/95 mm Hg or higher for intervention purposes.However, until the 1991 Systolic Hypertension in the Elderly Program (SHEP) trial, many physicians were reluctant to pay credence to the need for therapy of elevated systolic blood pressure (vide infra).The Framingham Heart Study and other epidemiological data demonstrated that the level of systolic blood pressure in individuals older than 45 years is a better determinant of morbidity and mortality than the diastolic counterpart.Isolated systolic hypertension(ISH), defined as a systolic blood pressure higher than 160 mm Hg with a diastolic blood pressure of 90 mm Hg or lower,is clearly related to stroke,coronary heart disease,heart failure,heart size,renal failure, and decreased renal size.A systolic blood pressure higher than 160 mm Hg doubles all-cause mortality; triples cardiovascular mortality, particularly in women; and increases cardiovascular morbidity by 2.5-fold in both sexes.Even stage 1 ISH between 140 and 159 mm Hg (diastolic blood pressure, ≤90 mm Hg) carries significantly increased cardiovascular morbidity and mortality.DIAGNOSISThe systolic blood pressure measured by cuff-mercury sphygmomanometer is comparable with that obtained by simultaneous direct intra-arterial recordings in normal individuals,patients with essential hypertension,and those with ISH.However, Mönckeberg medial sclerosis or calcinosis of the brachial artery was reported to produce a higher systolic pressure by the cuff method than the intra-arterial recording.This phenomenon was suspected by the Osler maneuver (ie, the arterial wall remains palpable even when the cuff pressure has been inflated above the level of the systolic pressure) in as many as 40% of the elderly patients in a small series from a tertiary care referral center.Nevertheless, the utility of this maneuver remains controversial. The diagnosis of ISH is made by exclusion of other causes of wide pulse pressure, ie, aortic regurgitation, severe anemia, thyrotoxicosis, Paget disease of the bones, arteriovenous fistulae, profound bradycardia, and Mönckeberg medial calcinosis.PREVALENCEIsolated systolic hypertension is present in 1.0% of the US population by the age of 55 years, 5.0% by the age of 60 years, 12.5% by the age of 70 years, and 23.6% by the age of 75 to 80 years, especially in women(Figure 1). Worldwide prevalence estimates of ISH in those between the ages of 60 and 69 years have varied from 1% in Israel to 24% in Norway.Percentage of the US population with isolated systolic hypertension (ISH), as derived from the data of Stalssen et al.ETIOPATHOLOGIC FEATURES OF SYSTOLIC HYPERTENSIONAttempts have been made to explain ISH because of increased arterial compliance, stroke volume, left ventricular ejection rate, and systemic vascular resistance.Arterial stiffness increases in elderly patients with ISH,but one studysuggests that an increase in arterial stiffness might be the result rather than a cause of this disorder. Whatever the mechanism of increased stiffness of the arterial system underlying this disorder, the systolic blood pressure increases, while the diastolic blood pressure decreases, resulting in increased pulse pressure. Pulse pressure is independently related to the risk of developing cardiac hypertrophy, myocardial infarction, and cardiovascular mortality.Reports on stroke volume and cardiac indexes in patients with ISH have been conflicting. Although the average systemic vascular resistance in elderly patients with ISH is similar to that in the normal population of various age groups older than 35 years,in many patients it is considered elevated in relation to respective cardiac outputs.Renin-sodium profiling of patients with ISH demonstrates even distribution in the groups with low and normal renin levels.Contrary to the previously published theory of volume dependency of patients with low-renin hypertension,the levels of plasma volume in the elderly patients with low renin levels and ISH were found to be within the normal range.The levels of hormones that might be involved in blood pressure regulation, such as plasma aldosterone, atrial natriuretic peptide, norepinephrine, and urinary metanephrines, are normal in patients with ISH.CONCERN OF LOWERING THE BLOOD PRESSURE IN ELDERLY PATIENTSA 20– to 40–mm Hg decrease in systolic blood pressure has been reported in 17% of normotensive, asymptomatic elderly people older than 70 years when they assumed the standing position.Thus, increasing orthostatic changes by antihypertensive therapy in elderly patients may be a matter of concern.Recent studiesin elderly patients with ISH on the hemodynamic and baroreflex response to orthostatic stress have revealed that, following successful antihypertensive therapy, reduction in systolic blood pressure on orthostasis was not significant following short- and long-term therapy, and the patients did not experience any untoward symptoms. Interestingly enough, the hormonal response of renin, aldosterone, atrial natriuretic peptide, and norepinephrine to orthostatic stress in patients with ISH was comparable with that of the normotensive elderly patients and those with essential hypertension.Such data should alleviate anxiety about producing symptomatic hypotension in most elderly patients with ISH.BENEFIT OF THERAPYA reduction in morbidity and mortality in elderly patients with ISH as a result of antihypertensive therapy was suggested based on a nonrandomized trial in the early 1960s.Recent data from the SHEPand the Syst-Eurotrials involving more than 9000 patients have shown that therapeutic control of ISH significantly reduces fatal and nonfatal stroke (approximately equal to 40%); clinical myocardial infarction, including coronary death (27%); and sudden deaths (32%) among major cardiovascular events. Absolute risk reduction for total stroke was 30 per 1000; and for major cardiovascular events, 55 per 1000. However, the change in all-cause mortality was only 13%, which was statistically insignificant. Nevertheless, the daily life activity score in these patients improved significantly.APPROACH TO THERAPYMost reportssuggest that individuals with an elevated systolic blood pressure in hospital clinics or physicians' offices, but with normal levels at home or on 24-hour ambulatory blood pressure monitoring (so-called white coat hypertension; prevalence, 20%), do not need drug therapy with antihypertensive agents. In those with stage 1 systolic hypertension (140-159 mm Hg) who also have increased cardiovascular risk, to our knowledge, no controlled trial has yet been done to demonstrate the benefit of therapy.Nevertheless, lifestyle modification, such as weight reduction by diet control, moderation of alcohol intake and dietary sodium, increased physical activity, adequate potassium intake, avoidance of tobacco smoking, and practice of relaxation techniques, should be positively encouraged in the population groups mentioned.A similar strategy should also be applied in patients with a systolic blood pressure between 160 and 180 mm Hg for 3 to 6 months before pharmacological drug therapy is added. In elderly patients with a systolic blood pressure higher than 180 mm Hg, in whom complications may develop more rapidly,a combination of lifestyle modifications and drug therapy should be instituted without delay.SELECTION OF ANTI
Archives of Family Medicine – American Medical Association
Published: Apr 1, 2000
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