Elsevier

Autonomic Neuroscience

Volume 88, Issue 3, 14 May 2001, Pages 181-186
Autonomic Neuroscience

Non-dipper phenomenon in essential hypertension is related to blunted nocturnal rise and fall of sympatho-vagal nervous activity and progress in retinopathy

https://doi.org/10.1016/S1566-0702(01)00238-7Get rights and content

Abstract

Although the relation between the blunted nocturnal decline in blood pressure and target organ damages is well established, the mechanism underlying these results has not been clarified. We investigated the relationship among heart rate variability, nocturnal change in blood pressure and the severity of cardiac and extracardiac target organ damages caused by essential hypertension. We studied 52 Japanese inpatients with essential hypertension (24 men and 28 women; mean age, 49±3 years). After a stabilization period of 1 week, ambulatory blood pressure monitoring (ABPM) and 24-h ECG monitoring were performed and analyzed. The non-dipper subjects were defined as those whose nocturnal decrease of mean BP was <10% of daytime blood pressure (BP). The sex, age, body mass index, duration of hypertension, and 24-h BP were similar in dipper (n=34) and non-dipper (n=18) patients. The left ventricular mass index (LVMI) was significantly higher and the degree of hypertensive retinopathy was significantly worse in the non-dipper patients than that of the dipper patients. In the non-dipper patients, indexes of time-domain analysis such as the sum of differences between adjacent RR intervals (NNDrms), the number of pairs of adjacent RR intervals differing by more than 50 ms in the entire recording (RR 50) were significantly lower than that of the dipper patients. Additionally, as for spectral analysis, daytime low frequency/high frequency (LF/HF) was higher and nighttime high frequency (HF) was lower than that of the dipper patients. Independent predictors were the 24-h mean blood pressure (MBP) for left ventricular hypertrophy (LVH), nighttime systric BP (SBP) for progress in retinopathy and duration of hypertension for proteinuria. In conclusion, decrease in parasympathetic nervous function and increase in sympathetic nervous function may contribute to occurrence of non-dipper phenomenon, as well as progress in retinopathy.

Introduction

Non-dippers (O'Brien et al., 1988) with persistently high blood pressure (BP) levels over 24 h have been characterized with increased risk of all target organ damages and cardiovascular morbid events Verdecchia et al., 1993, Shimoda et al., 1992, Verdecchia et al., 1994 compared with dippers, with appropriate nocturnal BP fall. As have been proven by past studies, the nocturnal decline in blood pressure is diminished in diseases that cause expansion of fluid volume, such as primary aldosteronism (Tanaka et al., 1983), toxemia of pregnancy (Rath et al., 1990) and renal failure (Baumgart et al., 1991). However, the mechanism of the blunted nocturnal decline of BP and of worse target organ damage in non-dipper essential hypertension has not been fully clarified. In terms of heart rate variability, some recent studies have reported that alteration in autonomic nervous activity influenced the abnormal patterns of diurnal BP variation Kohara et al., 1995a, Kohara et al., 1995b, Kario et al., 1997. A relationship between autonomic nervous function and target organ damages has also been reported Kohara et al., 1995a, Kohara et al., 1995b, Petretta et al., 1995, Mandawat et al., 1995.

We investigated the relationship among heart rate variability, nocturnal change of blood pressure and the severity of cardiac and extracardiac target organ damages to identify the independent predictors for these target organ damages as a result of essential hypertension.

Section snippets

Subjects and protocol

We studied 52 Japanese inpatients with essential hypertension (24 men and 28 women; mean age, 49±3 years). Hypertension was defined as a systolic blood pressure (SBP) >140 mm Hg and/or a diastolic blood pressure (DBP) >90 mm Hg on at least three different occasions at the outpatient clinic; and all the hypertensive patients were followed up in the First Department of Internal Medicine in our hospital before admission. The subjects had never been medicated with anti-hypertensive agents even in

Clinical characteristics and target organ damages of hypertension in dipper and non-dipper hypertensive patients

A dipper pattern was observed in 34 patients and a non-dipper pattern was observed in 18 patients of the total subjects. The clinical characteristics and target organ damages of the patients with dipper and non-dipper essential hypertension are shown in Table 1. The sex, age, BMI, duration of hypertension, urinary excretion of NE, PRA and PAC were similar in the two groups. Plasma norepinephrine was higher in the non-dipper group than in the dipper group. The LVMI was significantly higher and

Discussions

The clinical importance of the fact that the blunted nocturnal decline in blood pressure is associated with the progression of target organ damages is well established Verdecchia et al., 1993, Shimoda et al., 1992, Verdecchia et al., 1994, Rizzoni et al., 1992. The mechanisms responsible for a non-dipper phenomenon and the relationship between non-dipper phenomenon and target organ damages have not been fully clarified. Little discussion has been done about the hypothesis that autonomic nervous

Acknowledgements

This research was supported in part by a grant-in-aid for Scientific Research (11470518) from the Ministry of Education, Science and Culture, Japan.

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