Orthostatic Hypertension: When Pressor Reflexes Overcompensate

Joshua Fessel; David Robertson

Disclosures

Nat Clin Pract Nephrol. 2006;2(8):424-431. 

In This Article

Orthostatic Hypertension in the Context of Essential Hypertension

More recently, orthostatic hypertension and its potential clinical importance have been recognized in two groups of patients with essential hypertension. The first is elderly patients with essential hypertension. In one study, orthostatic hypertension occurred in approximately 11% of a sample of 241 elderly Japanese patients with essential hypertension[21] (defined as those whose SBP increased by ≥20 mmHg upon standing). In this study, the incidence of silent cerebrovascular infarct was higher in patients with orthostatic hypertension than in hypertensives without orthostatic hypertension. Notably, an approximately equivalent proportion of the study group exhibited orthostatic hypotension (23 of 241 patients). These patients were also at increased risk of silent cerebrovascular infarction.

The second group of essential hypertensives in which orthostatic hypertension has been observed are those who show abnormal diurnal variation in blood pressure—the 'extreme dipper' phenotype. These patients show a greater than normal decrease in SBP while sleeping. In one study examining the relationship between orthostatic hypertension and diurnal SBP variation, 72% of extreme dippers were shown to have orthostatic hypertension, compared with only 11% and 9% of dippers and nondippers, respectively.[23] Extreme dippers have been shown to have a higher prevalence (53%) of silent cerebrovascular infarction detected by MRI compared with dippers (29%).[21] Moreover, extreme dippers are at increased risk for overt stroke and tend to have a poorer prognosis in the event of a stroke.[24] It is thought that orthostatic hypertension has an important role in the overall increased risk for stroke in these patients, as two-thirds of strokes in extreme dippers occur in the morning, a time when these patients are known to experience a surge in blood pressure.

Matsubayashi and colleagues reported findings similar to those reported by Kario et al.[21] relating to orthostatic blood pressure changes and central nervous system (CNS) changes in a study of 334 elderly Japanese subjects.[25] In this study, 8.7% (29/334) of subjects exhibited orthostatic hypertension using the same definition as the aforementioned study, and 6% (20/334) of subjects exhibited orthostatic hypotension. Both orthostatic hypertensive (n = 15) and orthostatic hypotensive (n = 15) subjects had an increased prevalence of CNS lesions detectable by MRI compared with orthostatic normotensives (n = 30). In addition, scores on a number of cognitive and neurobehavioral metrics were lower in orthostatic hypertensives (n = 29) and orthostatic hypotensives (n = 20) than in orthostatic normotensives (n = 285). An important distinction of the Matsubayashi et al. study is that the study population was a general sample of elderly Japanese subjects, of whom only approximately 50% were taking antihypertensive medications. Thus, orthostatic hypertension (and orthostatic hypotension) may be associated with cerebrovascular infarction and with measurable neurocognitive deficits independent of the presence of essential hypertension.

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