Blood pressure and heart rate variability in elderly hypertensive patients

In elderly hypertensive patients (HP) blood pressure (BP) and heart rate (HR) control and variability seem to be affected by a reduced baroreceptor sensitivity, or autonomic dysfunction, and concomitant cardiovascular diseases. Therefore, the aim of present study was to investigate the circadian profiles and variability of BP and HR, by means of a 24-hour ambulatory BP monitoring, in a group of 22 elderly HP compared with those of a group of 24 middle aged patients with essential hypertension. Many differences in BP and HR profile and variability were observed in elderly HP when compared to those of middle aged HP, such as significantly lower diurnal diastolic BP values, lower nocturnal BP fall, lower diurnal HR but with a greater diurnal variability. Conversely, in middle aged HP a significantly greater diurnal systolic BP variability was observed, and a significant correlation was found between hourly diastolic BP and hourly HR values, while in elderly HP this correlation was not detectable. The changes in BP and HR profile and variability observed in elderly HP may play a role as risk factors for cardiovascular complications and indicate a dysfunction of autonomic and nonautonomic factors in BP control.     

高血压患者心率变异性的临床分析

通过对８２例高血压患者和６３例年龄相当的正常人２４小时心率变异性分析的研究表明：（１）高血压患者时域分析和频域分析的各项参数指标均减低。（２）高血压患者植物神经２４小时昼夜变化与正常人有差异，高频部分夜间明显降低，标志副交感神经活动失调（Ｐ＜０．０５）。（３）高血压伴心肌缺血者与无心肌缺血者的高频／低频比值差异有显著性（Ｐ＜０．０５）。     

Longitudinal analysis of heart rate variability in chronic hypertensive pregnancy.

In the US, it is currently estimated that 3% of pregnant women have chronic hypertension, or more than 100,000 pregnant women each year. The aim of our study was to investigate the adaptation of autonomic control during pregnancy based on heart rate variability analysis and to determine whether chronic hypertension during pregnancy has an impact on this adaptation. Sixteen pregnant women with chronic hypertension (CH group; mean age, 30 years; range, 25-33 years) and 35 healthy pregnant women serving as controls (CON group; mean age, 28 years; range, 24-30 years) were recruited for this longitudinal study. Beginning at the 20th week of pregnancy, the women were monitored every 4th week until delivery. For the analysis of heart rate variability, Portapres signals (200 Hz) were recorded for 30 min under resting conditions. Women in the CH group had significantly elevated blood pressure compared to controls (CON, 111 mmHg [105-132]; CH, 140 mmHg [132-148]; p<0.001). An increased heart rate was found in both groups during the second half of pregnancy. Consequently, decreased heart rate variability was observed, but was more pronounced in the CON group. There was a shift in the frequency bands indicated by an elevation of the low-to-high frequency ratio (LF/HF) in both groups due to a decrease in HF, and thus a significant increase in LFn (LF power in normalized units). However, VLF (power of very low frequency range) increased exclusively in the CON pregnancies. Our data showed no significant difference in heart rate variability between the subjects of the CH and CON groups. Longitudinal variations were detectable in normal pregnancies and also, albeit to a lesser degree, in chronic hypertensive pregnant women. Thus, our data indicate that patients with long-term hypertension are still able to respond to the physiological changes occurring during pregnancy.     

QT intervals and heart rate variability in hypertensive patients

Low heart rate variability and increased QT dispersion are risk factors for cardiac mortality in various patient populations. We studied dispersion of QT interval, i.e. an index of inhomogeneity of repolarization, and heart rate variability (HRV) i.e., a measure of cardiac autonomic modulation in 76 essential hypertension cases (45 women, 53.0 +/- 11.1 years, body mass index: 25.1 +/- 1.4 kg/m2) and 70 healthy cases (42 women, 54.0 +/- 10.2 years, body mass index: 25.5 +/- 1.6 kg/m2, p > 0.05). QT-corrected QT intervals and their dispersions were significantly higher in the hypertensive group (p < 0.0001), all showing a direct relation with the level of systolic and diastolic blood pressures, ventricular mass index and high Lown grade ventricular rhythm problems. Time domain measures like standard deviation of RR intervals, standard deviation of the means of all corrected RR intervals calculated at 5 min intervals (p < 0.0001), proportion of adjacent RR intervals differing by > 50 msec (p = 0.005), HRV triangular index (p = 0.007), the square root of the mean squared differences of successive RR intervals (p = 0.011), and the high frequency (HF, 0.16-0.40 Hz, p < 0.0001) part of the frequency domain measure of HRV were all decreased, whereas the low frequency (LF, 0.04-0.15 Hz, p = 0.013) part of the frequency domain measures and LF / HF ratio (p < 0.0001) were increased in hypertensive cases. Time domain and the HF part of frequency domain measures of heart rate variability showed an inverse relation with the increased levels of both systolic and diastolic blood pressures and Lown grading system of ventricular rhythm problems, whereas LF and LF / HF showed direct relations with high levels of systolic and diastolic blood pressures and high Lown grade ventricular rhythm problems. The measures of heart rate variability apart from LF and LF / HF were inversely related with the QT intervals and dispersions, whereas LF / HF was directly related with them. Therefore, we conclude that the levels of both systolic and diastolic blood pressures are related to the generation of ventricular rhythm problems either via increasing left ventricular mass which results in an increase in QT parameter measurements, or by altering heart rate variability measures indicating a disturbance in cardiac autonomic balance in essential hypertension.     

厄贝沙坦对中老年非杓型高血压及脉压的作用

目的 观察不同时间服用血管紧张素受体拮抗剂（ARB）对中老年非杓型高血压的降压疗效及血压昼夜节律的作用.方法 采用90217型无创动态血压监测仪监测动态血压,筛选出120例中老年非杓型高血压患者,按随机区组设计原则分为厄贝沙坦晨服组与晚服组,分别于7：00-8：00和19：00-20：00口服厄贝沙坦150 mg,共治疗8周,观察24 h动态血压,对两组治疗前后24 h平均血压,白天、夜间平均血压进行统计学分析.结果 对控制夜间高血压及纠正昼夜节律变化晚服组与晨服组比较差异有统计学意义（P〈0.01）.结论 对于非杓型中老年高血压患者,厄贝沙坦在晚上服用可以较好地控制夜间高血压负荷,纠正昼夜节律变化,提高夜间血压达标率.     

罗格列酮对老年高血压并胰岛素抵抗患者心率变异性的影响

目的:观察罗格列酮(rosiglitazone)对老年高血压并胰岛素抵抗患者心率变异性(HRV)的影响。方法:采用随机双盲、安慰剂对照研究方法,将62例老年原发性高血压并胰岛素抵抗患者随机分为罗格列酮组和安慰剂组,各口服罗格列酮4mg或安慰剂,每日1次,共16周,服药前后分别测定24h动态心电图、体质指数(BMI)、空腹胰岛素、空腹血糖、凝血因子Ⅰ和C反应蛋白。结果:罗格列酮组HRV时域及频域各项指标均有所提高(均P<0.01);胰岛素敏感性均显著提高(均P<0.01);空腹胰岛素、C反应蛋白和凝血因子Ⅰ明显降低(均P<0.01);24h平均收缩压和舒张压均降低(均P<0.05);空腹血糖和BMI差异无统计学意义(均P>0.05)。多元逐步回归分析结果表明空腹胰岛素是与HRV最为密切的因素(P<0.01)。结论:罗格列酮能有效改善老年原发性高血压并胰岛素抵抗症患者HRV,提高胰岛素敏感性,降低收缩压和舒张压,减少血液中心血管危险因子;空腹胰岛素是影响HRV的重要因素。     

Comparison of verapamil versus felodipine on heart rate variability in hypertensive patients.

OBJECTIVE: We evaluated the effect of two calcium channel blockers, verapamil and felodipine, on heart rate variability in hypertensive patients. DESIGN: Time and frequency domain measures of heart rate variability were obtained from 24 h Holter recording in 25 previously untreated hypertensive patients without left ventricular hypertrophy, before and after 3 months of verapamil slow-release treatment (240 mg once daily) or felodipine extended-release treatment (10 mg once daily). RESULTS: Blood pressure values decreased with both drugs. Measures of heart rate variability, comparable at baseline in the two groups, were unchanged after felodipine. After verapamil, the average RR interval, the square root of the mean of the squared differences between all adjacent normal RR intervals (r-MSSD) and the percentage of differences between all adjacent normal RR intervals > 50 ms (pNN50), measures of vagal modulation of heart rate, increased (from 735 +/- 67 to 827 +/- 84 ms, P < 0.001; from 30 +/- 10 to 44 +/- 15 ms, P < 0.001; and from 3 +/- 2 to 7 +/- 6%, P < 0.01, respectively) and were higher than after felodipine. The coefficient of variation, a measure that compensates for heart rate effects, increased only after verapamil (from 5.8 +/- 1.3% to 6.6 +/- 1.0%; P < 0.05). High frequency power and its coefficient of component variance, both representing the vagal modulation of heart rate, increased after verapamil (from 5.33 +/- 0.29 to 5.80 +/- 0.27 In units, P < 0.001 and from 1.9 +/- 0.3 to 2.2 +/- 0.25%; P < 0.05). Finally, the low to high frequency power ratio, an indicator of sympathovagal balance, with a high value suggesting a sympathetic predominance, decreased after verapamil (from 2.16 +/- 0.41 to 1.36 +/- 0.35; P < 0.001), confirming the improvement in vagal modulation of heart rate. CONCLUSION: In hypertensive patients, despite a comparable anti-hypertensive effect, verapamil, but not felodipine, has favourable effect on cardiac autonomic control.     

老年高血压心肌肥厚患者的年龄与心率变异指数

目的了解老年高血压心肌肥厚患者的年龄与心率变异性指数（ＨＲＶＩ）的关系。方法１７１例老年及老年前期高血压心肌肥厚患者经超声心动图和２４小时动态心电图测定左室质量指数（ＬＶＭＩ）、左室射血分数（ＬＶＥＦ）、ＨＲＶＩ，并采用多元逐步回归法分析了年龄与ＨＲＶＩ的关系。结果ＨＲＶＩ减低的发生率和平均ＨＲＶＩ在４５～５９岁组（４５例）为５７．８％，２４．７±９．１；在６０～７４岁组（７０例），为６７．１％，２２．９±１０．３；在≥７５岁组（５６例）为７６．８％，２０．９±８．７（Ｐ＜０．０５）。多元逐步回归分析显示，ＨＲＶＩ的变化与年龄（ｒ＝－０．２７４６，Ｐ＝０．０００１２）和ＬＶＭＩ（ｒ＝－０．４０１５，Ｐ＝０．０００２１）呈负相关关系，而与ＬＶＥＦ呈正相关关系（ｒ＝０．４２８３，Ｐ＝０．００００９）。结论老年高血压左心室肥厚患者随年龄增长ＨＲＶＩ逐渐减低。     

老年高血压患者心率变异与靶器官损害的相关性研究

目的探讨老年高血压患者心率变异（HRV）与靶器官损害的关系。方法选取老年高血压患者210例,其中单纯高血压组4l例,高血压伴左室肥厚（LVH）患者65例、伴肾功损害者53例、伴颈动脉IMT增厚患者51例;选择健康者50名作为对照组,进行心率变异性时域分析。对人选者做以下检查：心电图、超声心动图、24h动态心电图、颈动脉内膜-中层厚度（IMT）、血肌酐。结果老年高血压患者HRV各项指标低于对照组（P〈0．05）;高血压伴LVH组HRV与单纯高血压组比较,差异有统计学意义（P〈0．01）.高血压伴肾功损害及IMT增厚者HRV与单纯高血压组比较,差异有统计学意岁。’P〈0．05）。结论老年高血压靶器官损害患者的HRV减低,即自主神经对心脏的调节能力减弱;可通过自主神经功能受损程度来评估靶器官受损的程度和判断预后。     

The effects of fasting on heart rate variability in hypertensive patients

ABSTRACT

Heart rate variability (HRV) is an independent indicator of increased mortality in patients with myocardial infarction and congestive heart failure. The effects of fasting on the HRV are not known in hypertensive patients. Therefore, studying the effects of Ramadan fasting on hypertensive patients’ HRV seems reasonable to address.

We conducted a prospective study including 20 hypertensive patients with sinus rhythm. HRV was determined twice by ambulatory 24-hour Holter recordings at fasting during and after Ramadan.

Subjects mean age was 55 ± 11.8 years. Sex-ratio was 1.5. When two groups compared, statistically significant differences were found in terms of SDNN (113 ± 71 vs 140 ± 38, p = 0.001), SDANN (109.7 ± 45 vs 134.8 ± 48.3, p = 0.008), T power (2368.7 ± 121.3 vs 3660.5 ± 170.9, p = 0.03) and LF (552.2 ± 31.3 vs 903.7 ± 48.9, p < 0.0001) values.

HRV parameters were found to be decreased in Ramadan. Thus, Ramadan fasting enhances the activity of the sympathetic system in hypertensive patients.     

Spectral analysis of heart rate dynamics in elderly persons with postprandial hypotension.

Prior studies suggest that postprandial hypotension in elderly persons may be due to defective sympathetic nervous system activation. We examined autonomic control of heart rate (HR) after a meal using spectral analysis of HR data in 13 old (89 +/- 6 years) and 7 young (24 +/- 4 years) subjects. Total spectral power, an index of overall HR variability, was calculated for the frequency band between 0.01 and 0.40 Hz. Relatively low-frequency power, associated with sympathetic nervous system and baroreflex activation, was calculated for the 0.01 to 0.15 Hz band. High-frequency power, representing parasympathetic influences on HR, was calculated for the 0.15 to 0.40 Hz band. Mean arterial blood pressure declined 27 +/- 8 mm Hg by 60 minutes after the meal in elderly subjects, compared with 9 +/- 8 mm Hg in young subjects (p less than or equal to 0.0001, young vs old). The mean change in low-frequency HR power from 30 to 50 minutes after the meal was +19.4 +/- 25.3 U in young subjects versus -0.1 +/- 1.5 U in old subjects (p less than or equal to 0.02). Mean change in total power was also greater in young (19.0 +/- 26.6 U) subjects compared with old subjects (0.0 +/- 1.6 U, p greater than or equal to 0.02). Mean ratio of low:high-frequency power increased 3.1 +/- 3.3 U in young subjects vs 0.5 +/- 2.7 U in old subjects (p less than or equal to 0.01). The increase in low-frequency HR power and in the low:high frequency band ratio in young subjects is consistent with sympathetic activation in the postprandial period.(ABSTRACT TRUNCATED AT 250 WORDS)     

老年高血压患者家庭自测血压变异性与心率变异性的相关性研究

目的探讨老年高血压患者家庭自测血压变异性(BPV)与心率变异性的相关性。方法 2011年10月²013年4月,对172例老年高血压患者进行7d家庭自测血压以及24h动态心电图监测。根据家庭自测BPV三分位分为低变异性组56例、中变异性组62例和高变异性组54例。结果与低变异性组比较,中变异性组和高变异性组24h连续正常R-R间期的标准差(SDNN)、连续正常R-R间期均值的标准差(SDANN)、相邻正常R-R间期的差值均方根(rMSSD)及低频明显降低(P<0.05);与中变异性组比较,高变异性组SDNN、SDANN、rMSSD及低频明显降低(P<0.05)。多元线性逐步回归分析显示,家庭收缩压变异性与SDNN、SDANN、rMSSD和低频呈负相关(P<0.05),与极低频呈正相关(P<0.05);家庭舒张变异性与吸烟呈正相关(P<0.05),与SDNN呈负相关(P<0.05)。结论老年高血压患者BPV与24h心率变异性密切相关。     

高血压患者脉压与心率变异性的相关性研究

目的探讨高血压患者脉压与心率变异性改变的关系。方法对高血压宽脉压组45例、正常脉压组42例和正常血压脉压组(对照组)38例的心率变异性时域和频域参数进行分析。结果①高血压宽脉压组与正常脉压组、对照组比较,SDNN(98.3±31.9ms)、SDANN(88.3±28.6ms)、SDNNI(44.1±11.2ms)、rMSSD(16.2±10.8ms)、PNN50(12.5±7.2%)降低,LF(528±138ms2/Hz)、HF(278±1113ms2/Hz)也降低,LF/HF(1.90±0.76)增大,差异均有显著性意义(P均<0.05)。②高血压正常脉压组与对照组比较,SDNN(130.1±38.3ms)、SDANN(108.3±27.4ms)、SDNNI(44.1±11.2ms)均降低,差异有显著性意义(P均<0.05)。结论高血压患者自主神经功能均有不同程度的损害,高血压正常脉压患者以交感神经功能损害为主,宽脉压患者交感和副交感神经功能均有明显损害。表明高血压患者脉压宽窄与心脏自主神经功能的调节有关。     

Long-Term follow-up of the circadian rhythm of heart rate and heart rate variability in healthy elderly patients.

BACKGROUND: The long-term age-related changes in circadian rhythm of heart rate variability (HRV), that is, autonomic nervous activity, remain unknown in elderly people. METHODS AND RESULTS: Holter monitoring was conducted twice at an interval of 15 years in 15 healthy elderly patients (age: 70.0 +/- 4.1 years, at first monitoring, female: 10) and assessed the age-related changes in 24-h mean and hourly mean normal sinus R-R interval (mean NN), HRV (high frequency (HF) component, low frequency (LF) component and LF/HF) and the circadian rhythms. As a result, 24-h mean mean NN (0.976 +/- 0.115 vs 0.903 +/- 0.117 (s), p = 0.0019), LF/HF (1.681 +/- 0.731 vs 0.962 +/- 0.442, p = 0.0022), and LF (278.88 +/- 176.43 vs 179.19 +/- 132.33 (ms2), p = 0.0039) significantly decreased 15 years later, although 24-h mean HF (221.20+/-138.89 vs 310.78+/-296.73 (ms2), p = 0.1102) increased slightly. The hourly mean NN closely correlated with hourly HF and LF/HF throughout circadian rhythms both at first and second monitoring. In the morning hours, amplitude rates of all HRV indices increased significantly 15 years later. CONCLUSION: In elderly people, age-related changes in the 24-h mean heart rate (HR) were conversely dissociated from those of the 24-h mean HRV. However, the close correlation between hourly HR and HRV was preserved, even in very elderly patients. Additionally, the amplitude rates in HRV in the morning increased with age. These age-related changes of HR and HRV might be characteristic of elderly people.     

瑞芬太尼对中老年人心率及心率变异性的影响

目的: 观察瑞芬太尼对不同年龄组患者心率及心率变异性的影响,以及阿托品对心率的保护作用。方法: 选择行择期手术的全麻患者,先按年龄分组:中年(M,40～59岁)和老年(O,≥60岁),每一组又随机分为单纯应用瑞芬太尼(R)组和阿托品(A)预处理,共分为4个组（每组20例）:中年单纯瑞芬太尼组（RM）、老年单纯瑞芬太尼组（RO）、中年阿托品预处理组（ARM）和老年阿托品预处理组（ARO）。RM组和RO组静脉恒速泵入瑞芬太尼2 μg/kg,泵速为1 μg/(kg·min)。其余两组患者给药方式相同,只是在静脉应用瑞芬太尼之前30 min肌肉注射阿托品0.5 mg。记录用药前（T0）、用药后1 min(T1)、2 min(T2)、3 min(T3)、5 min(T5)、7 min(T7)等各时间点的心率(HR)、低高频比值(LF/HF)。结果: RM组和RO组患者的HR、LF/HF值在T1~T7各时间点,与T0相比均降低(P<0.05);而ARM组患者给药后的各时间点的HR、LF/HF值与T0相比较,未出现有统计学意义的变化;ARO组的HR和LF/HF值在给药后也出现有统计学意义的下降（P<0.05）,但与RO组相比,下降的幅度较小。结论: 静脉泵入瑞芬太尼时,中老年患者心率及心率变异性明显降低,而阿托品可以拮抗瑞芬太尼减慢心率的作用,因此瑞芬太尼应用于中老年患者时,提倡预先应用阿托品以预防心动过缓。     

Left ventricular mass and heart rate variability in middle-aged and elderly salt-sensitive hypertensive subjects

Previous reports have shown that in salt-sensitive hypertension a high dietary salt intake can increase sympathetic activity. We evaluated the influence of the autonomic nervous system on myocardial hypertrophy by power spectral analysis of heart rate variability in middle-aged and elderly salt-sensitive hypertensive subjects. We compared autonomic nervous system activity in 32 salt-sensitive hypertensive patients (15 subjects with mean age, 42.4+/-2.4 years and 17 subjects with mean age, 74.6+/-1.6 years) and 20 age-matched normotensive controls. Power spectral analysis detects four spectral components: total power (TP), high-frequency (HF), low-frequency (LF) and very-low-frequency (VLF) power. In the elderly subjects we found an association between the left ventricular mass index (LVMI) and the following variables: very-low frequency (P<0.0001), 24-h urinary sodium excretion (P<0.0001) and diastolic blood pressure (DBP) (P<0.0001). In contrast, in middle-aged subjects we found a significant association between the LVMI and LF (P<0.001). In middle-aged, but not in elderly salt-sensitive hypertensive subjects, increased sympathetic activity correlated with the LVMI (P<0.0001). Our findings suggest an association between sympathetic hyperactivity and the LVMI in middle-aged subjects with salt-sensitive hypertension.     

老老年高血压患者左心室肥厚与心律失常及心率变异性的关系研究

目的 探讨老老年高血压患者左心室肥厚(LVH)与心律失常及心率变异性(HRV)的关系.方法 纳入2012年10月至2014年7月于中国中医科学院广安门医院心内科住院的303例老老年高血压患者,根据是否合并左心室肥厚分为2组,检测24 h动态心电图心率变异性时域分析及超声心动图,观察两组间相关指标的差异.结果 老老年高血压合并LVH组较不合并LVH组房性、室性心律失常检出率增高,差异具有统计学意义(P＜0.05),两组PNN50、RMSSD、SDNN、SDANN的P值分别为0.573、0.198、0.110、0.812,未见统计学差异.结论 老老年高血压合并LVH患者心律失常的发生率明显增高,而老老年高血压合并LVH和不合并LVH患者心率变异性无明显差异.     

Spectral analysis of heart rate variability in diagnosis of vegetative autonomic dysfunction in patients with attacks of atrial fibrillation.

AIM: Elucidation of possible role of suprasegmental and segmental autonomic vegetative disturbances in pathogenesis of paroxysmal atrial fibrillation. MATERIAL: Untreated patients (n=22) with nonrheumatic paroxysmal atrial fibrillation and 10 healthy subjects. METHODS: Clinical cardiological and neurological examination, assessment of the state of vegetative nervous system, emotional sphere, patterns of sleep, and spectral analysis of heart rate variability. RESULTS: According to data of spectral analysis of heart rate variability patients with paroxysmal atrial fibrillation were characterized by marked vegetative dysfunction which was more pronounced in women, patients older than 52 years, with higher level of anxiety, with duration of symptoms longer than 6 years, and with predominantly nocturnal attacks. CONCLUSION: The data obtained should be considered in selection of therapy aimed at prevention of attacks of atrial fibrillation.     

阿替洛尔对老年冠心病人心率变异性的影响

目的　观察阿替洛尔对老年冠心病人心率变异性（ ＨＲＶ） 的影响，探讨其临床意义。　方法　将８６例老年冠心病人分为阿替洛尔组和对照组。阿替洛尔组在硝酸酯类扩冠药治疗基础上，加服阿替洛尔６－２５ ～１２－５ ｍ ｇ ，每日１ ～２ 次，用２４ｈ Ｈｏｌｔｅｒ 资料对２ 组的ＨＲＶ 进行分析对比。　结果　阿替洛尔组ＨＲＶ 参数中反映交感神经和迷走神经双重活性的ＳＤＮＮ（１２１－９７ ±２６－２０） ｍｓ 、ＳＤＡＮＮ（１０７－７７ ±２５－９０） ｍｓ 、ＳＤＮＮｉｎｄｅｘ（５０－１３ ±１８－０１） ｍｓ 及ＬＦ（３９８－８１ ±２８１－１２） ｍｓ２·Ｈｚ－ １较对照组有显著提高（ Ｐ＜ ０－０５） 。　结论　阿替洛尔对ＨＲＶ 的影响主要是通过改善交感神经与迷走神经的失衡而实现的，其对预防冠心病人恶性心律失常是有益的     

Blood pressure and heart rate variability in elderly patients with isolated systolic hypertension.

To investigate the circadian profiles of BP and heart rate in elderly patients with isolated systolic hypertension (ISH), the variability of BP and heart rate during day time (daytime) and the amplitudes of nocturnal fall were evaluated in ISH (n = 19) comparing with those of essential hypertensive patients (EHT, n = 18) and normotensive subjects (NT, n = 16) in the same age range. ISH showed a significantly wider BP variability during the day time and a greater amplitude of nocturnal fall compared with EHT and NT. However, the heart rate variability during the daytime and the amplitude of nocturnal fall were similar among the three groups. ISH showed a stronger correlation between BP and heart rate during 24 hours compared with EHT and NT. Approximately 80% of ISH showed a significant positive correlation between BP and heart rate. These results suggest that the BP of ISH patients is susceptible to fluctuations in autonomic nerve activity.