The two faces of hypertension: role of aortic stiffness.

Adult hypertension can be divided into two relatively distinct forms-systolic/diastolic hypertension in midlife and systolic hypertension of the aged. The two types differ in prevalence, pathophysiology, and therapy. The prevalence of systolic hypertension in the elderly is twice that of midlife hypertension. The systolic pressure is elevated in both forms, but the high diastolic pressure in midlife is due to a raised total peripheral resistance, whereas the normal or low diastolic pressure in the elderly is due to aortic stiffening. Aortic stiffness, as measured by the carotid/femoral pulse wave velocity, has been found to be a cardiovascular risk marker independent of traditional risk factors for atherosclerosis. Instead, it is related to microcirculatory disease of the brain and kidney and to disorders of inflammation. Loss of aortic distensibility is an inevitable consequence of aging, but a review of its causes suggests that it may be amenable to future pharmacologic therapy.