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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To identify rat strains suitable for studying age-related development of hypertension we compared pressures measured with the tail-cuff method in different groups of ageing Fischer 344, Wistar, or Sprague-Dawley rats. Preliminary experiments to establish optimal frequency of chronic blood pressure measurement in ageing rats showed that tail-cuff systolic pressures did not differ significantly whether taken weekly or monthly. Repeated tail-cuff measurements were comparable even when a common cuff size was used in different groups of rats with varying tail diameters. Additional studies were then carried out in 1-year old male Wistar and Sprague-Dawley rats to measure tail-cuff pressures monthly during the second year of age. Systolic and mean pressures increased progressively with age in both strains, as did body weight and heart rate, but the incidence of hypertension was higher in Sprague-Dawley than in Wistar rats. Elevations in mean pressures were sometimes more pronounced than those in systolic pressure. Two months after the last tail-cuff measurement, the presence of hypertension in Wistar rats was verified by the elevated mean pressures that were recorded from femoral artery catheters. Our results overall suggest that the predisposition to hypertension was higher in Sprague-Dawley than in Wistar or Fischer 344 rats of the same age, and also in males than in females of the same strain. Of all the different strains and sexes we compared, therefore, male Sprague-Dawley rats from 20 to 24 months of age may be the best model for studying the development of systolic hypertension with age.
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PMID:Tail-cuff detection of systolic hypertension in different strains of ageing rats. 189 Aug 83

The prevalence of hypertension increases with age. The majority of the hypertensive population is over age 55. Although the treatment of systolic hypertension remains incompletely understood, the reduction of diastolic hypertension with pharmacotherapy has been shown to reduce complications from hypertension in persons over age 55. The older hypertensive patient is at risk for the same complications as the younger patient: angina, myocardial infarction, arteriosclerosis obliterans, stroke, myocardial hypertrophy, congestive heart failure, and renal failure; the risk of sudden death and multi-infarct dementia in the older patient may be somewhat higher. The older hypertensive individual may have reduced plasma volume and defective salt and water conservation, reduced renal function, impairment of baroreceptor reflexes and sympathetic reactivity, and altered drug pharmacokinetics, or may have arteriosclerosis leading to pseudohypertension. Many circumstances interfere with adequate compliance with therapeutic regimens among the elderly. Concomitant medical conditions increase the possibility of drug interactions and require that the practitioner be able to adjust the antihypertensive program to the patient.
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PMID:Treatment considerations for the hypertensive patient over age 55. 189 46

Several trials have demonstrated a significant reduction in morbidity from cardiovascular disease with the treatment of diastolic hypertension in elderly persons. The pilot trial of the Systolic Hypertension in the Elderly Patient study showed a reduction in morbidity and mortality from stroke with less of a reduction in death from cardiac conditions in elderly patients who were treated. Isolated systolic hypertension in elderly persons has a particularly hazardous connection with morbidity and mortality from stroke and cardiovascular disease. The mechanisms of hypertension are different, if not greatly so, in the elderly population. Peripheral vascular resistance plays a major role. However, reduction in peripheral vascular resistance can still be demonstrated with exercise in older patients. Two major studies are ongoing--the Systolic Hypertension European trial and the Systolic Hypertension in the Elderly Patient trial. We await the outcome of these trials to learn more about the treatment of isolated systolic hypertension in elderly patients.
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PMID:Hypertension in the elderly patient. 192 89

Vascular dementia is the second most common type of dementia in the elderly after the dementia of Alzheimer's disease. Six forms of vascular dementia have been described: multi-infarct dementia, lacunar dementia, Binswanger's subcortical encephalopathy, cerebral amyloid angiopathy, white-matter lesions associated with dementias, and single-infarct dementia. Each is described. Severe dementia is found in 5% of persons over age 65 and in 15% to 20% of persons over age 80 years. Alzheimer's disease accounts for 50% to 60% of cases of severe dementia and vascular dementia for 10% to 20%; 20% of the patients have both disorders. The incidence of vascular dementia, which seems to be declining, is about 7/1,000 persons/year. Hypertension is the most powerful risk factor for all vascular dementias. Vascular dementias can be accurately diagnosed by using clinical and mental state examinations, Diagnostic and Statistical Manual of Mental Disorders criteria, ischemic scores, and computed tomography or magnetic resonance imaging. The most successful treatment of vascular dementia is the prevention of cerebral infarcts. Study of the incidence of vascular dementias and their treatment will be included in the European Trial on Systolic Hypertension in the Elderly (SYST-EUR) of 3,000 elderly hypertensive patients.
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PMID:Hypertension and the risk of dementia in the elderly. 200 54

Arterial compliance describes a change in the volume of arteries following a change in blood pressure. The physical basis of the compliance concept and experimental procedures in animals both indicate that the relation between arterial compliance and blood pressure pattern is often unclear. Compliance is pressure-dependent because of the biphasic elastin and collagen composition of arteries and, hence, decreases when blood pressure increases. Compliance also determines the pulsatile amplitude of the pressure wave by regulating the buffering function of an artery's face to the cardiac pump and, accordingly, its reduction induces a selective increase in systolic level. The questions are whether these theoretical and experimental phenomena can be extrapolated to human hypertension and whether they can be assessed from indirect measurement of arterial compliance by means of a time-domain analysis of arterial pressure and flow waves via various models of the arterial tree. Whatever the method and site of measurement, arterial compliance was found to be decreased in different forms of hypertension. This low compliance can be considered to have a causal role in elderly patients with isolated systolic hypertension. In contrast, in patients with systolo-diastolic hypertension physiologic and pharmacologic arguments exist against the fact that low arterial compliance may be the pure consequence of mean blood pressure elevation. Moreover, it is suggested that aging acts in concurrence with pressure elevation to decrease arterial compliance, and that in certain hypertensive patients additional factors, perhaps atherosclerotic in nature, contribute to impair the elastic properties of arteries.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Use of arterial compliance for evaluation of hypertension. 200 4

Event rates in relation to the number of elderly hypertensives treated were calculated from randomized analysis data from the 840 patients who completed the European Working Party on High Blood Pressure in the Elderly (EWPHE) trial. In all, the actively treated group had 29 fewer cardiovascular events per 1000 patient years. Putting this another way, treating 34 patients for 1 year would prevent one cardiovascular event. Moreover, as there were 14 fewer cardiovascular deaths and 11 fewer nonfatal strokes per 1000 patient years in the actively treated groups, we calculated that treating 71 or 91 elderly patients for 1 year would prevent one cardiovascular death or nonfatal stroke, respectively. Because of the higher baseline incidence of cardiovascular events in this study, there were greater gains in terms of absolute reductions in mortality and morbidity in treated elderly hypertensive patients than in younger patients in similar studies. Of the 840 patients who participated in the trial, 247 had systolic blood pressure greater than or equal to 160 mmHg and diastolic blood pressure less than or equal to 95 mmHg. In this group, blood pressure was reduced by 13/8 mmHg after 3 years in those randomized to active treatment compared to placebo. While patient numbers were insufficient to draw firm conclusions, their outcome on treatment was similar to that for patients on active treatment in the overall study. These results high-light the need for a rigorous assessment of the value of treating isolated systolic hypertension in the elderly.
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PMID:Further learnings from the European Working Party on High Blood Pressure in the Elderly (EWPHE) study: focus on systolic hypertension. 200 48

The percentage of persons in the United States over age 65--especially over 85--is increasing more rapidly than other age groups. Two thirds of people over age 65 have blood pressure higher than 140 mm Hg systolic or 90 mm Hg diastolic. Isolated systolic hypertension (systolic blood pressure greater than 160 mm Hg with diastolic blood pressure less than 90 mm Hg) is also highly prevalent. In a number of clinical trials, treatment of diastolic hypertension in the elderly has been shown to be beneficial, although the value of treatment of isolated systolic hypertension is not yet established. The benefit of antihypertensive therapy on the incidence of stroke and heart failure has been clearly established, but prevention of the atherosclerotic complications of high blood pressure (sudden death or myocardial infarction, for example) has not been convincingly demonstrated. Since clinical trials designed to investigate this atherosclerotic complication of hypertension have relied on stepped-care regimens (diuretics and beta blockers), the question arises whether the use of different drugs might have a better effect on prevention of myocardial infarction. The basis for this supposition includes the known adverse effects of diuretics and beta blockers on electrolytes, lipid metabolism, glucose metabolism, insulin resistance, and quality of life. Hypertension treatment in the 1990s will focus on the mechanisms by which blood pressure is lowered by various antihypertensive agents, as well as individualization of drug therapy based on coexisting diseases and conditions. Emphasis will be placed on use of monotherapy whenever possible; diuretics in low doses will probably be used more frequently for second-line therapy. In recognition of their lack of adverse lipid effects and their tolerability, first-line therapy with alpha blockers, angiotensin-converting enzyme inhibitors, and calcium antagonists will become increasingly common. The goal of antihypertensive therapy will be to extend the life expectancy of hypertensive patients to that of subjects without high blood pressure; hopefully, these new treatment approaches will bring us closer to that goal.
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PMID:Epidemiology and evaluation: steps toward hypertension treatment in the 1990s. 201 54

There is convincing evidence that all grades of persistent diastolic hypertension, especially in blacks, should be treated in order to prevent stroke and other cardiovascular complications. Studies are now in progress to gather additional information concerning isolated systolic hypertension, especially in the aged. Inasmuch as at least one half or more of stroke deaths in blacks develop as the result of hypertension, lowering blood pressure offers the perfect opportunity to reduce considerably the frequency of this devastating illness. The recent dramatic fall in U.S. stroke mortality, greatest in the black female, is a commendable achievement, but the flattening of the declining mortality curve over the past several years should be a cause for alarm and intensive investigation.
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PMID:Cerebrovascular disease in hypertensive blacks. 204

Cardiac output, blood volume, total peripheral resistance, and renal blood flow were measured in awake salt-sensitive and salt-resistant Dahl rats on normal rat chow (1% NaCl) and on high salt (8% NaCl) diets. Rats were studied after 4, 8, and 46 weeks on a 1% NaCl diet and after 4 and 8 weeks on an 8% NaCl diet. Salt-sensitive rats on 8% NaCl for 4 weeks developed systolic hypertension; by 8 weeks they developed greater systolic and also diastolic hypertension. Salt-resistant rats on 8% NaCl remained normotensive throughout the studies, although renal resistance decreased (p less than 0.05). At 4 weeks, hypertension in salt-sensitive rats on 8% NaCl was caused by increased blood volume and cardiac output (p less than 0.05), with normal total peripheral resistance. At 8 weeks, hypertension was due to increased total peripheral resistance (p less than 0.05); cardiac output was below normal despite persistent elevation of blood volume (p less than 0.05). Salt-sensitive rats on 1% NaCl for 46 weeks were hypertensive, with elevated total peripheral resistance (p less than 0.05); cardiac output decreased (p less than 0.05), whereas blood volume remained unchanged. Salt-resistant rats on 1% NaCl remained normotensive with no charges in hemodynamics. Salt-sensitive rats on 8% NaCl for 4 weeks had an increase in renal vascular resistance but no significant change in nonrenal resistance or total peripheral resistance. The increased total peripheral resistance in salt-sensitive rats on 8% NaCl for 8 weeks and on 1% NaCl for 46 weeks was a reflection of increases of both renal and nonrenal vascular resistance.(ABSTRACT TRUNCATED AT 250 WORDS)
Hypertension 1991 Jun
PMID:Dual hemodynamic mechanisms for salt-induced hypertension in Dahl salt-sensitive rats. 204 50

Cardiovascular disease in all its clinical manifestations progresses significantly as age advances and takes its heaviest toll in the elderly. Hypertension becomes the dominant risk factor for cardiovascular disease in this age group because of its high incidence. Traditionally, diastolic rather than systolic blood pressure has been regarded as the main risk factor for cardiovascular complications in hypertension, although it is becoming clearer that the risk of cardiovascular complications is likely to be associated mainly with systolic pressure in the elderly. Various intervention drug trials in elderly patients seem to indicate that hypotensive drug treatment can decrease cardiovascular mortality, mainly by decreasing cerebrovascular mortality. The EWPHE used a diuretic combination with methyldopa, and the HEP study used atenolol with a thiazide diuretic. The multicenter Systolic Hypertension in the Elderly Program (SHEPS) currently underway in the United States is likely to also provide some answers. The place of newer agents such as ACE inhibitors or calcium antagonists is still undetermined. Calcium antagonist drugs have been reported to be effective, and possibly more so in the elderly than in a younger population, although this assumption is not proven and may not be valid. Pharmacokinetic studies in the elderly are very few, although the studies reported indicate a reduced clearance. Studies also indicate that Nifedipine Retard tablets are effective, with a low incidence of adverse effects. There are no trials, however, looking at the long-term benefit of treating elderly hypertensive patients with either nifedipine tablets or other calcium-channel blockers.
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PMID:Hypertension in the elderly. 207 5


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