Postprandial hypotension is associated with asymptomatic cerebrovascular damage in essential hypertensive patients

Why do treated hypertensives suffer strokes? An internist's perspective

Despite widespread treatment of hypertension, stroke continues to be the third leading cause of death in the United States. Antihypertensive therapy is more effective in preventing hemorrhagic strokes than ischemic strokes. In order to understand the reasons why antihypertensive therapy is only partially successful in the eradication of ischemic strokes, differences in the pathogenesis and treatment of subtypes of stroke must be considered. There are three main stroke subtypes of ischemic strokes: small-vessel arteriopathic (lacunar), large-artery atherothrombotic, and cardioembolic. Hypertension is the major cause of lacunar strokes but plays a lesser role in the pathogenesis of atherothrombotic strokes. Antihypertensive therapy prevents the majority of lacunar strokes but may not have a major impact on the occurrence of atherothrombotic strokes. Due to impaired cerebral autoregulation, overtreatment of hypertension, especially in the elderly and in patients with previous strokes, may paradoxically lead to stroke (J-curve). Assuming that the majority of lacunar strokes are prevented by judicious antihypertensive therapy, future therapeutic efforts should concentrate on the prevention of atherothrombotic and cardioembolic strokes. In this regard, refinement of surgical techniques, pharmacologic approaches aimed at plaque stabilization, and the application of transesophageal echocardiography for the diagnosis of embolic strokes (and anticoagulation for a probable source) are promising. Besides the obvious reasons of noncompliance and inadequate therapy, overly aggressive treatment of hypertension in the elderly and stroke mechanisms unrelated to blood pressure may explain the occurrence of strokes despite our efforts to treat hypertension.

U-curve relationship between orthostatic blood pressure change and silent cerebrovascular disease in elderly hypertensives: orthostatic hypertension as a new cardiovascular risk factor

OBJECTIVES

The study investigated the clinical significance and mechanism of orthostatic blood pressure (BP) dysregulation in elderly hypertensive patients.

BACKGROUND

Although orthostatic hypotension (OHYPO), often found in elderly hypertensive patients, has been recognized as a risk factor for syncope and cardiovascular disease, both the clinical significance and the mechanism of orthostatic hypertension (OHT) remain unclear.

METHODS

We performed a head-up tilting test and brain magnetic resonance imaging (MRI) in 241 elderly subjects with sustained hypertension as indicated by ambulatory BP monitoring. We classified the patients into an OHT group with orthostatic increase of systolic blood pressure (SBP) of >or=20 mm Hg (n = 26), an OHYPO group with orthostatic SBP decrease of >or=20 mm Hg (n = 23), and a normal group with neither of these two patterns (n = 192).

RESULTS

Silent cerebral infarcts were more common in the OHT (3.4/person, p < 0.0001) and OHYPO groups (2.7/person, p = 0.04) than in the normal group (1.4/person). Morning SBP was higher in the OHT group than in the normal group (159 vs. 149 mm Hg, p = 0.007), while there were no significant differences of these ambulatory BPs between the two groups during other periods. The OHT (21 mm Hg, p < 0.0001) and OHYPO (20 mm Hg, p = 0.01) groups had higher BP variability (standard deviation of awake SBP) than the normal group (17 mm Hg). The associations between orthostatic BP change and silent cerebrovascular disease remained significant after controlling for confounders, including ambulatory BP. The orthostatic BP increase was selectively abolished by alpha-adrenergic blocking, indicating that alpha-adrenergic activity is the predominant pathophysiologic mechanism of OHT.

CONCLUSIONS

Silent cerebrovascular disease is advanced in elderly hypertensives having OHT. Elderly hypertensives with OHT or OHYPO may have an elevated risk of developing hypertensive cerebrovascular disease.

Postprandial hypotension

Postprandial hypotension is a prevalent condition in the elderly population and seems to be more common in frail elderly individuals who may be more susceptible to complications such as syncope and falls. Diagnosis is relatively easy and may be reversible in many cases. The epidemiology and pathophysiology of postprandial hypotension are not defined fully; however, a number of pathologic processes likely are involved, including abnormal sympathetic function, baroreceptor function, and vasoactive peptide release and activity. The precise relationship between symptoms and postprandial reductions in blood pressure is unclear. Blood pressure maintenance after a meal may depend on the interaction of some or all of the mechanisms outlined previously to compensate for the increase in bowel blood volume. The impairment of one or more of these mechanisms could result in inadequate compensation that leads to hypotension. If so, the presence of symptoms depends on that individual patient's ability to exercise adequate compensatory cerebral autoregulation. A hypertensive elderly patient may experience symptoms with only a small reduction in blood pressure, whereas a patient with autonomic failure may require a much larger fall in blood pressure to occur before they become symptomatic. The current definition of postprandial hypotension uses a threshold of 20 mm Hg as a cut off for diagnosis, but this may not be relevant to the presence or absence of symptoms. Further epidemiologic data are needed. Additionally, there is a lack of controlled trial evidence for the drugs that are used to treat this condition, and treatment often is carried out on a trial-and-error basis. Further research must be performed to identify the specific pathophysiology in certain patient groups, such as elderly hypertensive patients and those with autonomic failure, and to identify effective pharmacologic therapies that can be supported by randomized, placebo-controlled trials.

Lower standing systolic blood pressure as a predictor of falls in the elderly: a community-based prospective study

OBJECTIVES

We investigated prospectively the relationships among falls, physical balance, and standing and supine blood pressure (BP) in elderly persons.

BACKGROUND

Falls occur often and adversely affect the activities of daily living in the elderly; however, their relationship to BP has not been clarified thoroughly.

METHODS

A total of 266 community-dwelling elderly persons age 65 years or over (123 men and 143 women, mean age of 76 years) were selected from among residents of Coop City, Bronx, New York. Balance was evaluated at baseline using computerized dynamic posturography (DPG). During a one-year follow-up, we collected information on subsequent falls on a monthly basis by postcard and telephone follow-up.

RESULTS

One or more falls occurred in 60 subjects (22%) during the one-year follow-up. Women fell more frequently than men (28% vs. 16%, p < 0.03), and fallers were younger than nonfallers. Fallers (n = 60) had lower systolic BP (SBP) levels when compared with nonfallers (n = 206) (128 +/- 17 vs. 137 +/- 22 mm Hg for standing, p < 0.006; 137 +/- 16 vs. 144 +/- 22 mm Hg for lying, p < 0.02), whereas diastolic BP was not related to falls. Falls occurred 2.8 times more often in the lower BP subgroup (<140 mm Hg for standing SBP) than in the higher BP subgroup (> or =140 mm Hg, p < 0.0003), and gender-related differences were observed (p = 0.006): 3.4 times for women (p < 0.0001) versus 1.9 times for men (p = 0.30). Loss of balance, as detected by DPG, did not predict future falls and was also not associated with baseline BP levels. Multiple logistic regression analysis demonstrated that female gender (relative risk [RR] = 2.1, p = 0.02), history of falls (RR = 2.5, p = 0.008) and lower standing SBP level (RR = 0.78 for 10 mm Hg increase, p = 0.005) were independent predictors of falls during one year of follow-up.

CONCLUSIONS

Lower standing SBP, even within normotensive ranges, was an independent predictor of falls in the community-dwelling elderly. Elderly women with a history of falls and with lower SBP levels should have more attention paid to the prevention of falls and related accidents.

Silent stroke: pathogenesis, genetic factors and clinical implications as a risk factor

Silent stroke is frequently recognized in elderly persons. Diffusion-weighted magnetic resonance imaging has proved to be highly sensitive in the detection of recent silent stroke, and may further applications in the future. Silent stroke in healthy and asymptomatic individuals mainly comprises lacunar infarcts, which are often associated with white matter changes. Thus, analyses of risk factors and genetic factors in small-vessel diseases such as lacunar infarct and white matter changes may provide clues regarding the pathogenesis of silent stroke. Silent stroke may be a risk factor for clinical stroke and cognitive impairment, but prospective studies are required to confirm this.