OBJECTIVETo investigate the relationship among circadian blood pressure rhythm, autonomic nervous system and myocardial energy expenditure (MEE) level in patients with primary hypertension.

METHODSA total of 102 hypertensive and 45 normotensive subjects were recruited. According to blood pressure reduction rate at night, the hypertensive patients were divided into non-dipper group (NDH group, n=54) with a reduction rate of <10% and dipper group (DH group, n=48) with a reduction rate of ≥10%. The circadian blood pressure rhythm and heart rate variability were measured with ambulatory blood pressure monitoring and 24-hour electrocardiograph monitoring, respectively, and MEE was measured by Doppler echocardiography to analyze their correlations.

RESULTSSDNN, SDANN, SDNNindex, RMSSD, PNN50, and HF were significantly lower in the hypertensive patients than in the control group (P<0.05); these parameters, except for PNN50, were all significantly lower in NDH group than in DH group (P<0.05). The hypertensive patients had significantly higher MEE than the control group (P<0.05), and MEE was significantly higher in NDH group than in DH group (P<0.05). Bivariate correlation analysis showed significant correlations of MEE with SDANN in the hypertensive patients (P<0.01).

CONCLUSIONPatients with primary hypertension, especially those in NDH group, have impaired autonomic nervous system function. The hypertensive patients in NDH group show a more prominent increase in MEE in relation to sympathetic activation, suggesting the importance of restoring circadian blood pressure rhythm in the treatment of hypertension.