VARIABILITY OF BLOOD-PRESSURE AND HEART-RATE IN ESSENTIAL-HYPERTENSION

BACKGROUND: Blood pressure (BP) and heart rate (HR) show multiple oscillations. The aim of the present study was to evaluate their variability by means of a noninvasive device for the continuous recording of ambulatory BP. METHODS: A 24 hour recording was programmed (minimal interval 30 minutes) in 190 individuals: 35 normotensive individuals aged 46 +/- 20 years and 155 patients with essential hypertension aged 49 +/- 12 years. RESULTS: In the whole population a significant positive correlation was found between systolic BP (SBP) and its variability (r = 0.360; p < 0.001). This correlation was found for both normotensive (r = 0.506; p < 0.01) and hypertensive (r = 0.384; p < 0.001) groups. There also was significant positive correlation between HR and its variability in the overall population (r = 0.374; p < 0.001) and in the normotensive (r = 0.594; p < 0.001) and hypertensive (r = 0.356; p < 0.001) groups. There was a significant positive correlation between SBP and age in the whole population (r = 0.269; p < 0.001) and in the normotensive (r = 0.448; p < 0.001) and hypertensive (r = 0.193; p < 0.05) groups. When the individuals were divided in those older than 65 years and those younger than 60 years, with same levels of SBP and DBP, it was found that the variability (given as standard deviation) of both SBP and DBP were higher in the older group (similar SBP: 19 +/- 7/13 +/- 4 mmHg vs 15 +/- 4/11 +/- 3 mmHg, p < 0.01/ p < 0.01; similar DBP: 19 +/- 7/ 13 +/- 4 mmHg vs 15 +/- 5/11 +/- 3 mmHg, p < 0.001/ p < 0.01). Multiple regression analysis showed that the most important determinant of this variability was the baseline SBP value, followed by age. CONCLUSIONS: SBP and HR show a greater variability with higher baseline values. The variability of both SBP and DBP are greater in elderly patients.