Importance of blood pressure control over a 24-hour period.

BACKGROUND: The circadian rhythm of blood pressure (BP) is associated with a high span during the awake period and a low span during the sleep period. Of interest is that cardiovascular (CV) events occur more frequently in the early morning period, the time when BP and heart rate rise steeply.
OBJECTIVE: To provide an overview of circadian BP and its correlation with adverse clinical outcomes and to discuss strategies for optimizing BP control over 24 hours.
SUMMARY: Patients who have an excessive morning surge in BP and those who lack the normal nocturnal BP fall (nondippers) have been shown to have an excessive incidence of strokes, heart failure, and other CV events. While there are numerous pathophysiologic mechanisms underlying abnormalities in the 24-hour BP profile, including abnormalities in sympathetic nervous system activity, salt and volume balance, and activation of the renin-angiotensin aldosterone system, for many patients the mechanisms remain unclear. Nevertheless, several of these known abnormalities can be modified by clinical interventions, including proper timing of antihypertensive drug therapy and use of classes of antihypertensives for which a substrate exists to induce a pharmacologic effect. It is particularly important to use therapies that will provide control throughout a 24-hour dosing interval.
CONCLUSION: While interventional strategies have not yet been shown to alter clinical outcomes, it is important to be cognizant of their physiologic basis and take them into consideration when making decisions regarding appropriate antihypertensive therapy.