Blood pressure variability: its relevance for cardiovascular homeostasis and cardiovascular diseases.

Blood pressure (BP) is one of the most dynamic physiologic variables that is routinely measured in clinical practice and is characterized by continuous and significant changes beat-to-beat, over 24 h, day-to-day, and visit-to-visit. Under physiological conditions, these BP variations largely represent a response to environmental stimulations and challenges of daily life aimed at maintaining so-called cardiovascular "homeostasis". However, sustained increases in blood pressure variability (BPV) may also reflect alterations in cardiovascular regulatory mechanisms or underlying pathological conditions and may represent a source of damage to the cardiovascular system. The clinical significance and prognostic implications of these BP variations have been demonstrated by a series of clinical and population studies conducted in recent years, in which increasing BPV has been associated with a higher risk of subclinical organ damage, cardiovascular events, and cardiovascular and all-cause mortality, independent of elevated average BP values. This paper will review the available evidence on the current definitions, classification, and mechanisms responsible for different types of BPV by focusing on their relevance to cardiovascular homeostasis and cardiovascular disease.