Clinical consequences of age-related impairments in vascular compliance.

Advancing age is associated with progressive reductions in the vascular distensibility of major vessels. Two clinically relevant consequences of physiologically impaired arterial compliance of aging, increased systolic blood pressure and decreased carotid arterial baroreflex sensitivity, are discussed. While arterial thickening and stiffening with age are associated with increased systolic blood pressure, diastolic blood pressure is generally stable or even decreases slightly with advancing age. Thus, the prevalence of isolated systolic hypertension increases dramatically with age. This long-neglected abnormality has recently attracted attention, and the view that systolic hypertension is harmless and its treatment fraught with a high incidence of serious adverse effects has now been shown to be myth. Several studies indicate substantial risk associated with isolated systolic hypertension, especially with regard to increasing prevalence of stroke. A recent multicenter trial has shown that systolic blood pressure can be safely lowered with low doses of thiazide diuretics. Currently, a National Institutes of Health sponsored multicenter trial aims to determine whether treatment of isolated systolic hypertension is associated with reduced risk. Age-related impairments in baroreflex sensitivity reduce the capacity of normal elderly persons to increase the heart rate in response to hypotensive stress and contribute to the increased prevalence with advancing age of orthostatic hypotension. This must be taken into account in the design of pharmacologic treatment regimens in older persons.