Autonomic nervous system activity is independently associated with the risk of shift in the non-dipper blood pressure pattern

Abstract

An insufficient decrease in nocturnal blood pressure (BP) is a known factor in cardiovascular mortality. We aimed to determine whether autonomic nervous system (ANS) activity and its change over 2 years were associated with a shift to non-dipper status, independently of initial BP, in a general elderly population. From participants in the PROOF study, 600 subjects untreated for hypertension were selected (age at baseline: 65 years, men: 41.5%). Dipper/non-dipper status was defined using repeated measures of 24-h ambulatory BP at baseline and 2 years later. ANS activity was evaluated on the basis of 24-h heart rate variability at both examinations. Among the 454 dipper subjects at baseline, 26.2% became non-dippers. Multivariate analysis showed that a +1 between-subject s.d. increase in the very low frequency at baseline was associated with a decreased odds ratio for the shift to non-dipper status 2 years later (OR¼0.61 [0.41-0.91], P¼0.02). The within-subject change between the two measurements of day and night systolic BP and day diastolic BP also contributed significantly to the risk of shift to non-dipper status. Our results suggest that impaired ANS activity precedes an insufficient decrease in nocturnal BP independent of hypertension status. Keywords: ambulatory blood pressure; heart rate variability; non-dipper; sympathetic nervous activity INTRODUCTION An insufficient decrease in nocturnal blood pressure (BP) (nondipping) is recognized as a marker of end-organ damage and a predictor of cardiovascular and all-cause mortality, independently of hypertension status. 1-3 Our understanding of the pathophysiologic factors that may be involved in the mechanisms of the circadian variation of BP and the non-dipping pattern remains incomplete. Among the suspected determinants, autonomic nervous system (ANS) activity is shown to be associated with arterial BP level and involved in the control of the circadian variation of BP. 4,5 Previous cross-sectional studies have shown that ANS activity, evaluated by heart rate variability (HRV), was reduced in non-dipper, untreated hypertensive subjects. 6,7 A possible explanation of the nocturnal decrease in BP is that it results from a reduction of sympathetic nervous activity and impaired circadian rhythm in sympatho-vagal balance during sleep. 8,9 We aimed to assess whether ANS activity indices and their changes over 2 years, as evaluated by 24-h HRV, were associated with a shift to non-dipper status among subjects identified as dippers at study entry in a general elderly population not treated for hypertension.

Mechanisms Influencing Circadian Blood Pressure Patterns Among Individuals with HIV

“…One study reported that among HIV+ individuals, compared to HIV− individuals, resting heart rate was higher (69 vs. 57 beats per minute; p<0.001), and heart rate variation as measured by the standard deviation of normal-to-normal (SDNN) was lower (36 vs. 74 ms; p<0.01) [16]. In previous studies of the general population, autonomic and baroreflex dysfunction has been associated with masked hypertension and abnormal diurnal BP patterns [26,27]. A longitudinal study of 1011 French individuals aged 65 or older found that a standard deviation increase in very low frequency RR intervals was associated with an OR of 0.61 (95 % CI 0.41-0.91) for non-dipping BP [26].…”

“…In previous studies of the general population, autonomic and baroreflex dysfunction has been associated with masked hypertension and abnormal diurnal BP patterns [26,27]. A longitudinal study of 1011 French individuals aged 65 or older found that a standard deviation increase in very low frequency RR intervals was associated with an OR of 0.61 (95 % CI 0.41-0.91) for non-dipping BP [26]. However, it is not known whether the high prevalence of autonomic dysfunction in HIV+ individuals translates to an increase in adverse ABPM phenotypes.…”

A reduced heart rate variability is independently associated with a blunted nocturnal blood pressure fall in patients with resistant hypertension

“…Reduced HRV was also demonstrated to predict worse cardiovascular prognosis not only in patients with coronary heart disease [6,7] and heart failure [8,9] but also in diabetic and hypertensive individuals [10,11] and in elderly population [12]. Furthermore, a reduced HRV predicted the development of hypertension in normotensive individuals [13,14] and is associated with higher odds of having a nondipping pattern in hypertensive individuals [15,16].…”

“…The polysomnographic recording was manually evaluated by an experienced physician and sleep-wake determination, sleep staging and abnormal respiratory events were defined according to standard criteria [28]. Apnoea-hypopnoea index (AHI), which indicates the number of apnoea or hypopnoea events per hour of sleep, was calculated and OSA severity was graded accordingly: no OSA (AHI 5), mild OSA (AHI 6-15), moderate OSA (AHI [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] and severe OSA (AHI >30). OSA symptoms were evaluated by the Berlin questionnaire [29].…”

Blood pressure variability: Epidemiological and clinical issues

“…Alteration in autonomic function plays the pivotal role in creating BPV [30] and non-dippers are characterized with an abnormal pattern of autonomic activity with higher sympathetic and lower parasympathetic modulation [31][32]. The reverse dipping state has been recognized to be related with a sympathetic activation greater for magnitude that seen in the other conditions displaying abnormalities in night-time BP pattern [33].…”