Strategies for the evaluation and treatment of hypertension and some implications of blood pressure variability.

The distinction between normotension and hypertension, which is traditionally based on measurements of blood pressure made in the clinic, is arbitrary. The situation is further clouded by the fact that blood pressure varies greatly from moment to moment in any one individual, as shown by ambulatory recordings. The fundamental pattern of diurnal blood pressure variations is governed by the sleep-wakefulness cycle, on which the effects of different activities are superimposed. Although hyperreactivity of blood pressure to behavioral stimuli could in theory contribute to the elevation of blood pressure in hypertensive subjects, this would not by itself explain the sustained elevation of blood pressure that is usually seen throughout the day and night in such patients. It is not known how blood pressure variability contributes to the vascular changes associated with hypertension; three possibly relevant factors are the average level of pressure over time, the peaks of pressure, and the shape of the pressure waveform (dP/dt). Hyperreactivity of blood pressure occurring in the doctor's office may be of considerable practical importance in the evaluation of patients with mild hypertension and may confound the relationship between clinical and overall blood pressure and also the evaluation of the response to antihypertensive treatment. Recordings of blood pressure made outside the clinic may help to overcome these problems.