经变异非线性动力学分析的状态空间重构方法

本文讨论了在使用研究非线性动力学方法研究心率变异时的状态空间重构问题。通过对这一方法的理论基础的讨论,说明在非线性建模中直接使用ＲＲ间期不合理性。本文以嵌入学为基础提出了一个合理的建模方法,对临床数据进行了分析,并给出了对比分析结果。     

心率变异非线性动力学分析的状态空间重构方法

本文讨论了在使用研究非线性动力学方法研究心率变异时的状态空间重构问题.通过对这一方法的理论基础的讨论,说明在非线性建模中直接使用RR间期的不合理性.本文以嵌入学为基础提出了一个合理的建模方法,对临床数据进行了分析,并给出了对比分析结果.     

冠状动脉心脏病患者的心脏自主神经功能性重构浅析

目的:采用窦性心率震荡(heart rate turbulence,HRT)指标的震荡初始(turbulence onset,TO)、震荡斜率(turbulence slope,TS)评价冠状动脉心脏病患者的心脏自主神经的功能性重构。方法:选取89例厦门大学附属第一医院近两年来曾行动态心电图检查的可计算HRT相关指标的心内科住院患者,依照疾病谱分为陈旧性心肌梗死患者28例(A组)、稳定性心绞痛患者31例(B组),并设置行经皮冠状动脉介入治疗+支架植入术治疗至少半年后的心绞痛患者30例作为对照组1(C组)。另取具有相同的其他主要疾病背景的同年龄段人群122例作为对照组2(D组),对上述四组的TO和TS进行比较分析。结果:A,B组与C,D组的TS指标差异有统计学意义(P<0.05),TS指标异常程度与自主神经功能重构呈正相关(r=0.351,P<0.05)。结论:HRT的TS指标对心脏自主神经功能性重构具有一定的定量评价价值。     

不同心动周期序列的心率变异频谱分析

利用AR模型谱估计法对三种心动周期序列和同步的呼吸信号进行频谱分析,比较了三种心动周期序列用来分析心率变异性的异同,结果显示dRR(the difference between adjacent RR intervals)序列的功率谱主要表征了心率变异的HF,且改变呼吸条件时其HF/LF值比较敏感,RR序列对心率变异的LF和HF都有很好的反映,rRR(the remained RR sequence with the mean RR value removed)序列也反映了心率变异的LF和HF,但其LF不是很准确.     

心电RR间期序列的近似熵与Lempel-Ziv复杂度分析

目的：探究度量心率变异性（HRV）指标的稳定性和有效性。方法：以207名心律失常患者在服用氟卡尼前后所得到的心电RR间期序列为实验数据，将长RR序列分割成多个短序列，计算出短序列的Lempel-ziv复杂度（LZC）和近似熵（ApEn），还计算了长RR序列相邻两个正常间期的差值均方根（RMSSD）、平均值、标准差以及心率变异系数等指标。结果：经比较发现LZC能明显地反映出氟卡尼对抑制患者HRV的效果，服药后的RMSSD降低（P〈0．0001），每段LZC也减少（P〈0．05）。结论：结果表明，用LZC和RMSSD等指标分析药物对HRV的作用是可行的。     

Aging Effects on Cardiac and Respiratory Dynamics in Healthy Subjects across Sleep Stages

Study Objectives:

Respiratory and heart rate variability exhibit fractal scaling behavior on certain time scales. We studied the short-term and long-term correlation properties of heartbeat and breathing-interval data from disease-free subjects focusing on the age-dependent fractal organization. We also studied differences across sleep stages and night-time wake and investigated quasi-periodic variations associated with cardiac risk.

Design:

Full-night polysomnograms were recorded during 2 nights, including electrocardiogram and oronasal airflow.

Setting:

Data were collected in 7 laboratories in 5 European countries.

Participants:

180 subjects without health complaints (85 males, 95 females) aged from 20 to 89 years.

Interventions:

None.

Measurements and Results:

Short-term correlations in heartbeat intervals measured by the detrended fluctuation analysis (DFA) exponent α₁ show characteristic age dependence with a maximum around 50–60 years disregarding the dependence on sleep and wake states. Long-term correlations measured by α₂ differ in NREM sleep when compared with REM sleep and wake, besides weak age dependence. Results for respiratory intervals are similar to those for α₂ of heartbeat intervals. Deceleration capacity (DC) decreases with age; it is lower during REM and deep sleep (compared with light sleep and wake).

Conclusion:

The age dependence of α₁ should be considered when using this value for diagnostic purposes in post-infarction patients. Pronounced long-term correlations (larger α₂) for heartbeat and respiration during REM sleep and wake indicate an enhanced control of higher brain regions, which is absent during NREM sleep. Reduced DC possibly indicates an increased cardiovascular risk with aging and during REM and deep sleep.

Citation:

Schumann AY; Bartsch RP; Penzel T; Ivanov PC; Kantelhardt JW. Aging effects on cardiac and respiratory dynamics in healthy subjects across sleep stages. SLEEP 2010;33(7):943-955.     

Cardiac autonomic dynamics during sleep are lost in patients with TIA and stroke

Ischaemic stroke is accompanied by important alterations of cardiac autonomic control, which have an impact on stroke outcome. In sleep, cardiac autonomic control oscillates with a predominant sympathetic modulation during REM sleep. We aimed to assess cardiac autonomic control in different sleep stages in patients with ischaemic stroke. Forty‐five patients enrolled in the prospective, multicentre SAS‐CARE study but without significant sleep‐disordered breathing (apnea–hypopnea index < 15/hr) and without atrial fibrillation were included in this analysis. The mean age was 56 years, 68% were male, 76% had a stroke (n = 34, mean National Institutes of Health Stroke Scale [NIHSS] score of 5, 11 involving the insula) and 24% (n = 11) had a transitory ischaemic attack. Cardiac autonomic control was evaluated using three different tools (spectral, symbolic and entropy analysis) according to sleep stages on short segments of 250 beats in all patients. Polysomnographic studies were performed within 7 days and 3 months after the ischaemic event. No significant differences in cardiac autonomic control between sleep stages were observed in the acute phase and after 3 months. Predominant vagal modulation and decreased sympathetic modulation were observed across all sleep stages in ischaemic stroke involving the insula. Patients with ischaemic stroke and transitory ischaemic attack present a loss of cardiac autonomic dynamics during sleep in the first 3 months after the ischaemic event. This change could represent an adaptive phenomenon, protecting the cardiovascular system from the instabilities of autonomic control, or a risk factor for stroke, which precedes the ischaemic event.     

Sleep problems and heart rate variability over the working day

The purpose of this study was to discover whether greater sleep problems are associated with reduced heart rate variability during working hours and at night, and to determine whether this association is in part mediated by experienced affective states. This study involved 199 working women with a mean age of 33.8years. Sleep problems were assessed with the Jenkins Sleep Problems Scale, and the Day Reconstruction Method was used to measure positive affect and stress on the evening before and during the working day. Heart rate variability was indexed by the mean square root of the successive standard difference in heart period. Disturbed sleep was inversely related to heart rate variability during the working day (P=0.022), independently of demographic and behavioural confounders. Additional adjustment for positive affect and stress did not lead to further reductions in the association between sleep problems and reduced heart rate variability over the work day. Sleep problems were not predictive of reduced night-time heart rate variability. This report extends the findings from experimental studies and clinical samples, and suggests that disturbed sleep might impair heart rate variability in real life settings, in particular during working hours. Reduced heart rate variability might be a potential pathway linking sleep problems with cardiovascular disease. Based on the current data there was little evidence that the inverse associations between sleep problems and heart rate variability were mediated by experienced affective states.     

心率变异性在反映心脏自主神经损伤和重构中的应用

缺血预适应和急性心肌梗死恢复期都会出现心脏自主神经的变化,心率变异性（HRV）是无创测量心自主神经活动的重要方法.研究自主神经的变化能为疾病机理和临床用药研究提供理论基础,所以监测预适应和心梗后的HRV有着重要意义.本文综述了预适应和心梗恢复期在HRV上的体现,并将HRV的变化与生理生化证据相联系,分析了缺血预适应对自主神经的保护作用和心梗后用HRV检测自主神经恢复的可行性.同时还对心率变异性今后的研究方向做了展望.     

Changes in Cardiac Variability after REM Sleep Deprivation in Recurrent Nightmares

Study Objectives:

To assess whether dysfunctional autonomic regulation during REM sleep as indexed by heart rate variability (HRV) is a pathophysiological factor in frequent nightmares (NMs).

Design:

Monitoring with polysomnography (PSG) and electrocardiography (ECG) for 3 consecutive nights: Night 1 (N1), adaptation night; N2, administration of partial REM sleep deprivation; N3, recovery night. Differences between NM and control (CTL) groups assessed for ECG measures drawn from wakefulness, REM sleep, and Stage 2 sleep on both N1 and N3.

Setting:

Hospital-based sleep laboratory

Participants:

Sixteen subjects with frequent NMs ( ≥ 1 NM/week; mean age = 26.1 ± 8.7 years) but no other medical or psychiatric disorders and 11 healthy comparison subjects ( < 1 NM/month; mean age = 27.1±5.6 years).

Results:

NM and CTL groups differed on 2 REM sleep measures only on N1; the NM group had longer REM latencies and REM/NREM cycle durations than did the CTL group. No differences were found on time domain and absolute frequency domain ECG measures for either N1 or N3. However, altered HRV for the NM group was suggested by significantly higher LFnu, lower HFnu, and higher LF/HF ratio than for the CTL group.

Conclusions:

Results are consistent with a higher than normal sympathetic drive among NM subjects which is unmasked by high REM sleep propensity. Results also support a growing literature linking anxiety disorders of several types (panic disorder, posttraumatic stress disorder (PTSD), generalized anxiety disorder) to altered HR variability.

Citation:

Nielsen T; Paquette T; Solomonova E; Lara-Carrasco J; Colombo R; Lanfranchi P. Changes in cardiac variability after rem sleep deprivation in recurrent nightmares. SLEEP 2010;33(1):113-122.     

Cardiac autonomic activity during daytime nap in young adults

The current study investigated both sympathetic and vagal autonomic patterns during a daytime sleep in 25 healthy adults (23.2 ± 2.4 years). Pre‐ejection period (PEP; related inversely to beta‐adrenergic sympathetic activity), the interval between consecutive R‐waves (RR) and frequency‐domain heart rate variability (HRV) were computed during pre‐nap wakefulness and undisturbed sleep stages. Results showed sleep‐related changes in RR and HRV measures, whereas PEP decreased significantly from pre‐nap to sleep, showing no differences across sleep stages. Moreover, pre‐nap PEP and HFnu (the normalized unit of the high‐frequency component of HRV) were associated negatively with sleep latency and wake after sleep onset. These results indicate a marked autonomic output reduction during daytime sleep, with different stage‐dependent fluctuations for sympathetic and vagal activity. Importantly, pre‐nap autonomic activity seems to modulate subsequent sleep quality.