Short- and Long-Term Blood Pressure Variability

I t has long been known that blood pressure (BP) is characterized by an array of spontaneous variations. 1 That is, BP values vary markedly within the 24 hours because of day-night changes but also because of differences among hours, minutes, and even adjacent beats. They also show variations over more prolonged periods because of differences among days, months, and seasons, 2 also with a trend for systolic BP to increase over the years and for diastolic BP to display an age-related biphasic change. his article summarizes current knowledge on short-term (within the 24 hours) and long-term BP variability. Mention will be made of the following: (1) factors responsible for BP variations and mechanisms through which they occur; (2) the relationship of BP variability with BP mean values in absence and during antihypertensive treatment; and (3) the prognostic significance of BP variability. Current limitations of the studies on BP variability will be also discussed to emphasize what future studies should address.