Ivabradine Improves Heart Rate Variability in Patients with Nonischemic Dilated Cardiomyopathy

Background

Ivabradine is a novel specific heart rate (HR)-lowering agent that improves event-free survival in patients with heart failure (HF).

Objectives

We aimed to evaluate the effect of ivabradine on time domain indices of heart rate variability (HRV) in patients with HF.

Methods

Forty-eight patients with compensated HF of nonischemic origin were included. Ivabradine treatment was initiated according to the latest HF guidelines. For HRV analysis, 24-h Holter recording was obtained from each patient before and after 8 weeks of treatment with ivabradine.

Results

The mean RR interval, standard deviation of all normal to normal RR intervals (SDNN), the standard deviation of 5-min mean RR intervals (SDANN), the mean of the standard deviation of all normal-to-normal RR intervals for all 5-min segments (SDNN index), the percentage of successive normal RR intervals exceeding 50 ms (pNN50), and the square root of the mean of the squares of the differences between successive normal to normal RR intervals (RMSSD) were low at baseline before treatment with ivabradine. After 8 weeks of treatment with ivabradine, the mean HR (83.6 ± 8.0 and 64.6 ± 5.8, p < 0.0001), mean RR interval (713 ± 74 and 943 ± 101 ms, p < 0.0001), SDNN (56.2 ± 15.7 and 87.9 ± 19.4 ms, p < 0.0001), SDANN (49.5 ± 14.7 and 76.4 ± 19.5 ms, p < 0.0001), SDNN index (24.7 ± 8.8 and 38.3 ± 13.1 ms, p < 0.0001), pNN50 (2.4 ± 1.6 and 3.2 ± 2.2 %, p < 0.0001), and RMSSD (13.5 ± 4.6 and 17.8 ± 5.4 ms, p < 0.0001) substantially improved, which sustained during both when awake and while asleep.

Conclusion

Our findings suggest that treatment with ivabradine improves HRV in nonischemic patients with HF.     

原发性高血压合并2型糖尿病患者心率变异性与心脏变时功能不全的特点及相关性

目的 探讨原发性高血压合并2型糖尿病患者的心率变异性和心脏变时功能不全特点. 方法 原发性高血压合并2型糖尿病患者与健康人各40例,行24 h动态心电图检查,计算心脏变异性指标SDNN、SDANN、RMSSD、PNN50;行平板运动试验检查,计算运动中最大心率、心脏变时指数、心率储备率,分析心脏变时指数和心率储备率与SDNN、SDANN、RMSSD、PNN50的相关性. 结果 原发性高血压合并2型糖尿病患者SDNN、SDANN 、RMSSD、PNN50均较健康者降低（P〈0.01）.最大心率、心脏变时指数、心率储备率明显低于健康者（P〈0.01）;SDNN、SDANN、RMSSD及PNN50与心脏变时指数（r=0.522、0.472、0.337、0.321）和心率储备率（r=0.541、0.480、0.351、0.285）均存在明显正相关. 结论 原发性高血压合并2型糖尿病患者心脏自主神经受损明显,表现为迷走神经功能减退和交感神经兴奋性增高.     

老年高血压合并糖尿病患者心率变异性及其昼夜变化临床分析

目的研究老年高血压合并糖尿病患者的心率变异性(HRV)及其昼夜变化规律,探讨老年糖尿病患者心脏自主神经变化的临床意义。方法选择87例原发性高血压患者(EH组)及68例高血压合并糖尿病患者(EH+DM组),监测24 h动态心电图,进行HRV时域指标SDNN、SDANN、SDNN Index、RMSSD、PNN50的分析。比较2组间HRV指标的差异以及HRV昼夜指标差异。结果 EH+DM组较EH组24 h、日间、夜间HRV各项指标均明显降低,且有统计学差异;EH组SDNN以及RMSSD呈昼低夜高,但无明显统计学差异,SDNN Index和PNN50仍呈昼低夜高现象(P0.01);EH+DM组SDNN以及RMSSD呈昼高夜低现象(P0.05),SDNN Index和PNN50昼夜间无统计学差异。结论老年高血压合并糖尿病患者HRV显著降低,高血压患者昼夜节律已有明显受损,高血压合并糖尿病患者昼夜节律进一步受损,心脏自主神经功能失调。     

老年急性心肌梗塞心率变异时域分析

目的分析急性心肌梗塞（ＡＭＩ）后老年患者心率变异（ＨＲＶ）时域指标，了解ＡＭＩ后ＨＲＶ变化。方法以多单位协作方式对１５７例ＡＭＩ后２周的老年患者行动态心电图检测ＨＲＶ时域法５项指标，并与健康老年组对比分析。数据经ＥｐｉＩｎｆｏ（６．０）统计软件处理。结果①ＡＭＩ患者的正常Ｒ－Ｒ间期标准差（ＳＤＮＮ）、平均值的标准差（ＳＤＡＮＮ）和标准差的平均值（ＳＤＮＮＩｎｄｅｘ）低于对照组（Ｐ＜０．０１），而相邻正常Ｒ－Ｒ间期差值的均方根（ＲＭＳＳＤ）和相邻正常Ｒ－Ｒ差值大于５０ｍｓ记数占总Ｒ－Ｒ间期数的百分比（ＰＮＮ５０）虽低于对照组，但无显著差异（Ｐ＞０．０５）。②ＡＭＩ后ＨＲＶ时域５项指标男、女性别间无显著性差异（Ｐ＞０．０５）。③ＳＤＮＮ、ＳＤＡＮＮ和ＳＤＮＮＩｎ－ｄｅｘ在心肌梗塞各部位间无显著差异（Ｐ＞０．０５），ＲＭＳＳＤ和ＰＮＮ５０前间壁低于下壁心肌梗塞（Ｐ＜０．０５）。结论老年人ＡＭＩ后ＨＲＶ降低。反映交感神经活性的ＳＤＮＮ、ＳＤＡＮＮ和ＳＤＮＮＩｎｄｅｘ和反映迷走神经活性的ＲＭＳＳＤ和ＰＮＮ５０２组指标变化不相同。     

脑梗死患者心率变异性分析(附50例报告)

目的　研究脑梗死患者的自主神经功能状态。方法　应用时域法对 5 0例脑梗死患者进行心率变异性分析。结果　脑梗死组与正常对照组相比所有 R- R间期均值的标准差 (SDNN)明显降低 (10 2 .0 6± 2 8.5 1,137.0 6± 2 9.0 8) ms,P<0 .0 1,HRV三角指数明显降低 (2 5 .86± 9.18,37.5 7± 14 .88;P<0 .0 5 )。相邻 R- R间期之差的均方根值 (RMSSD)、爱丁堡指数 (p NN5 0 )较正常对照组低 ,但无统计学意义。脑梗死患者心率变异昼夜比较RMSSD夜间高于日间 (18.70± 7.30 ,2 6 .2 3± 8.85 ) m s,P<0 .0 5。余指标昼夜有所变化但无统计学意义。脑梗死首次发作组与非首次发作组相比 SDNN、RMSSD、p NN5 0、HRV三角指数等指标无明显差别。结论　脑梗死患者的自主神经功能以交感神经活性占优势 ,心率变异程度降低 ,且失去了正常的昼夜规律。脑梗死后自主神经功能的改变主要与本次发作有关     

Ethnic differences and heritability of heart rate variability in African- and European American youth

This study investigated whether heart rate variability (HRV) in young African-Americans differed from that in young European Americans. It further examined the genetic and/or environmental sources of HRV variance and to what extent they depend on ethnicity or gender in young twins. Subjects were available from 1 data set including 166 subjects (mean age 16 +/- 2 years; 63 African-Americans) and another including 219 twins (11 singletons [4 African-Americans] and 104 pairs [42 African-Americans]; mean age 15 +/- 2 years). HRV was measured over 256 RR intervals in a supine position. Two time-domain variables, the SD of normal RR intervals (SDNN) and the root-mean-square of successive differences (RMSSD) of normal RR intervals, and 3 frequency-domain variables, high-frequency (HF) power, low-frequency (LF) power, and the LF power/HF power ratio, were used. African-Americans had higher RMSSDs (p <0.01) and HF power (p = 0.047) and lower LF power/HF power ratios (p <0.01) than European Americans. These differences remained significant after adjusting for covariates. All HRV parameters were heritable; estimated heritability ranged from 32% to 71%. Model fitting showed no ethnic or gender differences for any measure. SDNN, RMSSD, and HF power were strongly correlated (r values >0.8). One factor explaining >90% of the variance for all 3 measures was identified. The heritability of this combined HRV score was 70%. In conclusion, this study suggests that ethnic differences in HRV already exist in youth, with African-Americans having greater HRV than European Americans. High heritability estimates for HRV measures were observed, and no differences in HRV heritability estimates were noted for ethnicity or gender.     

Cardiovascular autonomic function analysis using approximate entropy from 24‐h heart rate variability and its frequency components in patients with type 2 diabetes

Aims/Introduction

The principal aim of the present study was to investigate the cardiovascular autonomic system status of diabetes patients using approximate entropy (ApEn) extracted from 24-h heart rate variability (HRV) and its frequency components.

Materials and Methods

A total of 29 healthy controls and 63 type 2 diabetes patients were included. Participants’ 24-h HRV signals were recorded, and decomposed and reconstructed into four frequency components: high, low, very low and ultra low. The total 24-h HRV and its four components were divided into 24 1-h segments. ApEn values were extracted and statistically analyzed. Four traditional HRV indices, namely standard deviation of the RR intervals, root mean square of successive differences, coefficient of variance of RR intervals and ratio of low to high power of HRV, were also calculated.

Results

The low-frequency component contained the most abundant non-linear information, so was potentially most suitable for studying the cardiovascular system status with non-linear methods. ApEn values extracted from low- and high-frequency components of healthy controls were higher than those of diabetes patients. Except for root mean square of successive differences, standard deviation of the RR intervals, low to high power of HRV and coefficient of variance of RR intervals of healthy controls were all higher than those of diabetes patients.

Conclusions

The results showed that ApEn contained information on disorders of autonomic system function of diabetes patients as traditional HRV indices in time and frequency domains. ApEn and three traditional indices showed accordance to some degree. Non-linear information in subcomponents of HRV was shown, which is potentially more effective for distinguishing healthy individuals and diabetes patients than that extracted from the total HRV. Compared with diabetes patients, the cardiovascular system of healthy controls showed information of higher complexity, and better regulation function in response to changes of environment.     

Cardiovascular Autonomic Dysfunction in Patients with Morbid Obesity

Background

Morbid obesity is directly related to deterioration in cardiorespiratory capacity, including changes in cardiovascular autonomic modulation.

Objective

This study aimed to assess the cardiovascular autonomic function in morbidly obese individuals.

Methods

Cross-sectional study, including two groups of participants: Group I, composed by 50 morbidly obese subjects, and Group II, composed by 30 nonobese subjects. The autonomic function was assessed by heart rate variability in the time domain (standard deviation of all normal RR intervals [SDNN]; standard deviation of the normal R-R intervals [SDNN]; square root of the mean squared differences of successive R-R intervals [RMSSD]; and the percentage of interval differences of successive R-R intervals greater than 50 milliseconds [pNN50] than the adjacent interval), and in the frequency domain (high frequency [HF]; low frequency [LF]: integration of power spectral density function in high frequency and low frequency ranges respectively). Between-group comparisons were performed by the Student’s t-test, with a level of significance of 5%.

Results

Obese subjects had lower values of SDNN (40.0 ± 18.0 ms vs. 70.0 ± 27.8 ms; p = 0.0004), RMSSD (23.7 ± 13.0 ms vs. 40.3 ± 22.4 ms; p = 0.0030), pNN50 (14.8 ± 10.4 % vs. 25.9 ± 7.2%; p = 0.0061) and HF (30.0 ± 17.5 Hz vs. 51.7 ± 25.5 Hz; p = 0.0023) than controls. Mean LF/HF ratio was higher in Group I (5.0 ± 2.8 vs. 1.0 ± 0.9; p = 0.0189), indicating changes in the sympathovagal balance. No statistical difference in LF was observed between Group I and Group II (50.1 ± 30.2 Hz vs. 40.9 ± 23.9 Hz; p = 0.9013).

Conclusion

morbidly obese individuals have increased sympathetic activity and reduced parasympathetic activity, featuring cardiovascular autonomic dysfunction.     

Reliability of Ultra‐Short ECG Indices for Heart Rate Variability

Background: Heart rate variability (HRV) is an accepted and reliable means for assessing autonomic nervous system dysfunction. A 5‐minute measurement of HRV is considered methodologically adequate. Several studies have attempted to use shorter recordings of 1–2 minutes or 10 seconds. The aim of this study was to determine the reliability of HRV parameters calculated from ultra‐short electrocardiogram recordings. Methods: Seventy healthy volunteers were recruited for the study. HRV was evaluated for 5 minutes according to accepted procedures. Thereafter, HRV parameters were recalculated from randomly selected 1‐minute and 10‐second intervals. The standard and ultra‐short measurements were correlated using intraclass correlation coefficients. Results: Good correlations between the 5‐minute electrocardiograms (ECGs) and both the 1‐minute and 10‐second ECGs were noted for average RR interval, and root mean square of successive differences in RR intervals (RMSSD). No correlation was noted for standard deviation of the RR interval (SDNN) and several other HRV parameters. Conclusions: RMSSD, but not SDNN, seem a reliable parameter for assessing HRV from ultra‐short (1 minute or 10 seconds) resting electrocardiographic recordings. Power spectral analysis and evaluation of other HRV parameters require longer recording periods. Further research is required to evaluate the importance of ultra‐short RMSSD for cardiovascular risk stratification. Ann Noninvasive Electrocardiol 2011;16(2):117–122     

Effects of cigarette smoking on the circadian rhythm of heart rate variability

BACKGROUND: The effects of cigarette smoking on the circadian rhythm of heart rate variability (HRV) are not known. METHODS: We studied the effects of cigarette smoking on the circadian rhythm of HRV in 24 smoking and 21 non-smoking healthy subjects. Twenty-four hour ambulatory electrocardiograms were recorded and time domain parameters of HRV (SDNN [standard deviation of all R-R intervals], SDANN [standard deviation of the averages of R-R intervals in all 5-minute segments of the entire recording], RMSSD [the square root of the mean of the sum of the squares of differences between adjacent R-R intervals]) were determined for the entire 24-hour period and for each 3-hour period. RESULTS: In total, SDNN and SDANN were significantly lower in smokers than non-smokers (116 +/- 26 vs 136 +/- 27, p < 0.05 for SDNN, 109 +/- 25 vs 121 +/- 24, p < 0.05 for SDANN). However, there were no statistical differences between smokers and non-smokers in heart rate (81 +/- 9 vs 76 +/- 10, p > 0.05) and RMSSD (32 +/- 12 vs 37 +/- 18, p > 0.05). These HRV parameters showed a circadian variation: they increased at night and decreased during the day in both groups. The parameters were lower in smokers than non-smokers during daytime (especially, between 8-14 hours). However, no differences were detected during night-time. CONCLUSIONS: Time domain parameters of HRV (SDNN, SDANN and RMSSD) in both smoking and non-smoking healthy subjects have a circadian rhythm. SDNN and SDANN were lower in smokers than non-smokers during daytime.     

AUTO-CPAP治疗对老年阻塞性睡眠呼吸暂停低通气综合征患者心率变异性的影响

目的研究老年阻塞性睡眠呼吸暂停低通气综合征（OSAHS）患者心率变异性（HRV）的改变,探讨自动调节持续气道正压通气（AUTO-CPAP）治疗对其的影响。方法根据睡眠呼吸暂停低通气指数（AHI）,选取老年轻度（520）OSAHS患者及对照组共3组,每组各20例进行多导睡眠图（PSG）及动态心电图监测,采用时域分析法定量分析HRV,测定全程记录中每5 min窦性心搏R-R（NN）间期标准差的平均值（ASDNN）、所有的窦性心搏RR间期的标准差（SDNN）、全程记录中每5 min NN间期平均值的标准差（SDANN）及相邻NN间期差值的均方根（RMSSD）。其中20例老年中重度OSAHS患者行AUTO-CPAP治疗3月后复查PSG及HRV。结果（1）老年轻度及中重度OSAHS组与对照组比较,SDNN、SDANN的差异均有显著性（P〈0.05或P〈0.01）。老年中重度OSAHS组与对照组比较,RMSSD的差异也有显著性（P〈0.05）。（2）老年中重度OS-AHS组治疗后与治疗前比较,AHI、夜间最低动脉血氧饱和度（SaO2）及SDNN、SDANN、RMSSD的差异均有显著性（P〈0.05或P〈0.01）。结论老年OSAHS患者的HRV出现异常,AUTO-CPAP治疗可显著改善老年中重度OSAHS患者的HRV。     

Relationships between reduced heart rate variability and pre-clinical cardiovascular disease in patients with type 2 diabetes

Aims

Reduced heart rate variability (HRV), an early sign of diabetic cardiovascular autonomic neuropathy (CAN), is associated with worse cardiovascular outcomes. The objective was to evaluate relationships between HRV parameters and three pre-clinical cardiovascular disease markers (left ventricular hypertrophy [LVH], aortic stiffness and carotid atherosclerosis) in type 2 diabetes.

Methods

In a cross-sectional study, 313 patients with type 2 diabetes performed 24-h Holter monitoring, carotid ultrasonography (intima-media thickness and plaques measurements), aortic pulse wave velocity measurement and echocardiography (left ventricular mass index [LVMI] measurement). Time-domain HRV parameters were the standard deviation of all normal RR intervals (SDNN), the standard deviation of the averaged normal RR intervals for all 5 min segments (SDANN), the root mean square of differences between adjacent R-R intervals (rMSSD), and the percentage of adjacent R-R intervals that varied by >50 ms (pNN50). Multivariate linear and logistic regressions assessed associations between HRV parameters and the three markers of pre-clinical cardiovascular disease.

Results

Patients with reduced HRV had longer diabetes duration, greater prevalences of microvascular complications, lower physical fitness, and higher heart rate, glycated hemoglobin, albuminuria and LVMI than patients with normal HRV. On multivariate regressions, after adjustments for several confounders, reduced SDNN and SDANN were independently associated with LVH and aortic stiffness. No HRV parameter was associated with carotid atherosclerosis.

Conclusions

Two reduced HRV parameters, SDNN and SDANN, which reflect cardiovascular autonomic imbalance, were associated with LVH and aortic stiffness, markers of pre-clinical cardiovascular disease. These findings may offer insights into physiopathological mechanisms linking CAN to worse cardiovascular prognosis.     

Comparison of heart rate variability and treadmill exercise score in patients with stable coronary artery disease

Depressed heart rate variability (HRV) is associated with increased mortality and morbidity with various forms of heart disease, and the Duke treadmill score (DTS) provides diagnostic and prognostic information for the evaluation of patients with coronary artery disease (CAD). Our study was aimed at assessing any possible correlation between HRV and DTS in stable CAD. We evaluated the correlation between the HRV assessed by using 24 hour ambulatory ECG monitoring, and treadmill exercise score in 37 patients with angiographically proven and clinically stable CAD. In univariate analysis, DTS showed a significant negative correlation with age (r=–0.89, p<0.01) and a significant positive correlation with the square root of the mean of the sum of the squares of differences between adjacent R-R intervals (RMSSD) (r=0.67, P<0.05), percent difference between adjacent normal R-R intervals >50 ms (PNN50) (r=0.69, P<0.05), and mean of the standard deviation of all R-R intervals in all the 5-minute intervals (HRVM) (r=0.63, P<0.05). There is no significant correlation between DTS and standard deviation of all R-R intervals (SDNN), standard deviation of the averages of R-R intervals in all 5-minute segments of the entire recordings (SDANN) and standard deviation of the SDNN in all the 5-minute intervals (HRVSD). In multiple regression analysis, age was the only independent significant predictor of DTS (p<0.01). DTS decreased with advancing age. SDNN, SDANN, RMSSD, HRVM and HRVSD were not apparent predictors for detecting of DTS. Age was an independent predictor of DTS. Although DTS was correlated with RMSSD, PNN50 and HRVM in patients with stable CAD, time domain parameters of HRV were not appearent predictor for DTS.     

Heart rate variability in physically active individuals: reliability and gender characteristics

Purpose

To evaluate the reliability of short-term recordings (five minutes) of heart rate variability (HRV) and the association between HRV and gender.

Methods

HRV time- and frequency-domain parameters were calculated in 44 physically active students (21 males and 23 females) over four consecutive days. A Suunto t6 heart rate monitor was used to obtain inter-beat intervals (IBIs) that were then transferred to Kubios HRV analysis software. The relative reliability [intra-class correlation (ICC)] and absolute reliability, [typical error of measurement (TEM) and typical error of measurement as a percentage (TEM%)] of the HRV parameters were then calculated for day 2 versus day 3 and day 3 versus day 4, with day 1 being a familiarisation day. The following HRV parameters were calculated: (1) time domain: resting heart rate (RHR), R–R intervals (IBI), standard deviation of normal-to-normal intervals (SDNN), root mean square differences of the standard deviation (RMSSD), percentage of beats that changed more than 50 ms from the previous beat (pNN50); and (2) frequency domain: low-frequency normalised units (LFnu), high-frequency normalised units (HFnu), low-frequency to high-frequency ratio in normalised units (LF/HFnu). An analysis of variance (ANOVA) with Tukey post-hoc testing was performed to compare HRV parameters in males and females. Significance was set at p ≤ 0.05.

Results

The ICCs for both relationship 1 and 2 indicated primarily good to excellent (> 0.8) relative reliability. The lowest value was found in the LF/HFnu ratio (ICC = 0.36) for males. Absolute reliability was low with TEM% greater than 10% for all HRV parameters, except IBIs. Females demonstrated better relative (higher ICCs) and absolute reliability (lower TEM and TEM%) compared to males for the frequency domain. The relative and absolute reliability for the time domains were similar except for SDNN where the absolute reliability was higher in males. ANOVA illustrated significant gender differences for the LF/HFnu ratio (41% higher in males, p = 0.003), HFnu (12% higher in females, p = 0.02) and IBI (21% higher in females, p < 0.0001).

Conclusions

Short-term recordings of HRV over three consecutive days demonstrated a high relative reliability. However, a low absolute reliability indicated large day-to-day random variation in HRV, which would make the detection of intervention effects using HRV difficult in individual participants. Females were shown to have a higher parasympathetic modulation of HRV, which may indicate an underlying cardioprotective mechanism in females compared to males.     

Screening for diabetic cardiac autonomic neuropathy using a new handheld device

Background

Cardiac autonomic neuropathy (CAN) is a serious complication of longstanding diabetes and is associated with an increased morbidity and reduced quality of life in patients with diabetes. The present study evaluated the prevalence of CAN diagnosed by reduced heart rate variability (HRV) using a newly developed device in a large, unselected, hospital-based population of patients with diabetes.

Methods

The study examined 323 patients consisting of 206 type 1 diabetes (T1DM) patients and 117 type 2 diabetes (T2DM) patients. The new handheld prototype Vagus™ was used to screen for CAN. Three different standardized cardiac reflex tests were performed to calculate HRV: 30:15 ratio, E:I ratio, and the Valsalva maneuver. An abnormal HRV in one test is indicative of early CAN, and if two or more tests show abnormal HRV, the diagnosis of CAN is established.

Results

In total, 86% of examined patients completed all three tests. Each test was completed by more than 90% of the patients. The prevalence of established CAN was 23%, whereas 33% of the patients had early signs of CAN. The prevalence was higher in T2DM patients (27.8%) than in T1DM patients (20.6 %), p = .02. Patients with CAN were older and had a longer duration of diabetes, higher systolic blood pressure, more nephropathy and retinopathy, and a higher vibration threshold.

Conclusions

Cardiac autonomic neuropathy is frequent in both T2DM and T1DM patients, especially in those with other late diabetes complications. Screening for CAN with the new device is feasible.     

2型糖尿病患者无症状心肌缺血心率变异性的研究

目的冠心病是2型糖尿病主要心血管并发症,且经常表现为无症状心肌缺血（SMI）,本研究观察2型糖尿病患者SMI发作与心率变异性的相关性。方法在我院行运动负荷心肌灌注显像检查的患者中,选取1个月内做过动态心电图监测的157名无冠心病临床症状的2型糖尿病患者,其中34例为SMI患者;123例为无心肌缺血发作患者,并在其中随机选37例为对照组。结果SMI的发生率为21．6％;SMI组除24小时平均心率高于无心肌缺血组外。心率变异性各参数中：总体标准差、均值标准差、标准差均值、差值的均方根和差值〉50ms的百分比与无心肌缺血组相比较均明显下降。结论心率变异性减低与2型糖尿病合并SMI明显相关,而心率变异性减低作为评价心脏神经自主病变的早期信号,说明2型糖尿病合并SMI的发病与心脏自主神经病变密切相关,心率变异性或可作为无症状的2型糖尿病患者SMI筛查的指标之一。     

Exercise training improves heart rate variability in older patients with heart failure: a randomized, controlled, single-blinded trial

Reduced heart rate variability (HRV) in older patients with heart failure (HF) is common and indicates poor prognosis. Exercise training (ET) has been shown to improve HRV in younger patients with HF. However, the effect of ET on HRV in older patients with HF is not known. Sixty-six participants (36% men), aged 69±5 years, with HF and both preserved ejection fraction (HFPEF) and reduced ejection fraction (HFREF), were randomly assigned to 16 weeks of supervised ET (ET group) vs attention-control (AC group). Two HRV parameters (the standard deviation of all normal RR intervals [SDNN] and the root mean square of successive differences in normal RR intervals [RMSSD]) were measured at baseline and after completion of the study. When compared with the AC group, the ET group had a significantly greater increase in both SDNN (15.46±5.02 ms in ET vs 2.37±2.13 ms in AC, P=.016) and RMSSD (17.53±7.83 ms in ET vs 1.69±2.63 ms in AC, P=.003). This increase was seen in both sexes and HF categories. ET improved HRV in older patients with both HFREF and HFPEF.     

Nonlinear Methods to Assess Changes in Heart Rate Variability in Type 2 Diabetic Patients

Background

Heart rate variability (HRV) is an important indicator of autonomic modulation of cardiovascular function. Diabetes can alter cardiac autonomic modulation by damaging afferent inputs, thereby increasing the risk of cardiovascular disease. We applied nonlinear analytical methods to identify parameters associated with HRV that are indicative of changes in autonomic modulation of heart function in diabetic patients.

Objective

We analyzed differences in HRV patterns between diabetic and age-matched healthy control subjects using nonlinear methods.

Methods

Lagged Poincaré plot, autocorrelation, and detrended fluctuation analysis were applied to analyze HRV in electrocardiography (ECG) recordings.

Results

Lagged Poincare plot analysis revealed significant changes in some parameters, suggestive of decreased parasympathetic modulation. The detrended fluctuation exponent derived from long-term fitting was higher than the short-term one in the diabetic population, which was also consistent with decreased parasympathetic input. The autocorrelation function of the deviation of inter-beat intervals exhibited a highly correlated pattern in the diabetic group compared with the control group.

Conclusion

The HRV pattern significantly differs between diabetic patients and healthy subjects. All three statistical methods employed in the study may prove useful to detect the onset and extent of autonomic neuropathy in diabetic patients.     

Long-chain,n-3 fatty acids and physical activity — Independent and interactive associations with cardiac autonomic control

Background/objectives

Intake of the marine-based, n-3 fatty acids and engagement in physical activity are inversely related to cardiac morbidity and mortality. Among putative mechanisms, both n-3 fatty acids and physical activity may act through modulation of autonomic control of the cardiovascular system. This investigation examined the independent and interactive associations of n-3 fatty acids (eicosapentaenoic and docosahexanenoic acid; EPA, DHA) and physical activity with heart rate variability (HRV).

Methods

Subjects were 259 healthy 30–54 year-old adults. Serum phospholipid fatty acid composition was employed as a biomarker of dietary n-3 fatty acid exposure. Physical activity based on the Paffenbarger questionnaire was coded as < or ≥ 2000 kcal/week. Standard time-domain (standard deviation of normal-to-normal intervals and root-mean squared of successive differences; SDNN, RMSSD) and frequency domain (high frequency and low frequency power) measures of HRV were derived from resting electrocardiographic recordings.

Results

In linear regression models with covariate adjustment for age, gender and race, greater n-3 fatty acid exposure was associated with greater SDNN and RMSSD, and high physical activity was associated with greater RMSSD. n-3 fatty acid exposure also predicted variation in SDNN, RMSSD, and high-frequency power in interaction with physical activity. Specifically, n-3 fatty acid exposure covaried positively with these three HRV indices only among participants expending 2000 kcal per week or more in physical activity. These latter findings were noted for DHA but not EPA.

Conclusions

These results suggest that the cardiovascular benefits of n-3 fatty acid consumption may be mediated, in part, by effects on cardiac autonomic control and may be dependent upon concomitant habitual exercise.     

培哚普利对老年特发性阵发性心房纤颤患者心率变异性的影响

目的 探讨培哚普利对老年特发性阵发性心房纤颤（IPAF）患者心率变异性的影响.方法 连续选择2001年4月-2003年4月在我院就诊的老年IPAF患者50例,均给予培哚普利治疗4周,治疗前后均进行24 h动态心电图检查和心率变异性分析.结果 治疗后患者正常的RR间期的标准差（SDNN）、相邻的RR之差的均方根（RMSSD）、每5 min的平均RR间期的标准差（SDANN）和相邻的RR之差大于50 ms占总窦性心搏的百分数（PNN50）均高于治疗前（P＜0.05）.结论 培哚普利可以提高老年IPAF患者的心率变异性.