Circadian profiles of blood pressure and heart rate of apparently healthy metropolitan Japanese.

The circadian waveform in blood pressure (BP) and heart rate (HR) was explored in metropolitan Japanese. Clinically healthy subjects (50 women and 50 men, aged 40-59 years) were selected for the study of computing a peer-group reference standard. Hypertensive subjects diagnosed by conventional criteria (systolic(S)BP/diastolic(D)BP > or = 160/90 mmHg) also volunteered for this study. Each was to provide measurements of SBP, DBP, and HR at 15 min intervals over 48 h by using an ambulatory monitor ABPM-630 (Colin Medical, Komaki, Japan). Reference limits were computed as 90% prediction limits specified by the circadian stage. Data in intervals of 30 min, displaced by 15 min, were used for the computation of these limits. Those time-qualified reference limits were reconstructed as 'three-component chronodesms' with the two harmonics (12 h and 8 h) in conjunction with the fundamental period (24 h). The coefficient of harmonics needed was determined by discrete Fourier transform (DFT). A diagnosis based on office BP readings was confirmed chronobiologically. As a result, the circadian BP profiles did not exceed the upper limit in 27/107 hypertensives for SBP and in 30/107 hypertensives for DBP. In conclusion, chronobiologic approaches improve the sensitivity and the reliability of diagnosis.