影响心率变异因素的研究进展

临床医师和电生理学家早在1933年就注意到,健康人在静息状态下呈现ＲＲ间期的周期性变化,这种变化主要受呼吸、体位、压力感受器和温度调节的影响,并证实是通过影响交感和迷走神经活动来改变ＲＲ间期的周期性,正常人交感迷走神经保持一定的紧张度,互相制约,互相影响达到动态平衡,使成年人心率保持在60100ｂｐｍ,任何兴奋交感神经,减低迷走神经张力,抑制迷走神经反射的因素,都可使ＲＲ间期周期性变化减少,ＲＲ间期的微小变化称心率变异(ＨＲＶ)。ＨＲＶ作为反映神经体液因素对心血管精细调节的敏感指标,在临床具有很好的应用价值,众多的研究…     

Heart Rate Variability in Heart Failure

The autonomic nervous system has an important role in the development and progression of the heart failure syndrome. Increased sympathetic, reduced parasympathetic, and impaired baroreceptor activity are well-documented features of heart failure. The analysis of heart rate variability can give insight into these autonomic abnormalities. A number of techniques now exist for assessing heart rate variability, and in general they reflect the known autonomic abnormalities. Power spectral analysis of RR variability has been claimed to reflect sympathovagal balance, but the reduced or absent low-frequency component in heart failure is paradoxical. It is likely that the absent low-frequency component in heart failure reflects impaired baroreceptor function. Although these various techniques of heart rate variability may be useful, reliability and reproducibility are problematic in this area. Better, more refined techniques for the noninvasive assessment of autonomic and baroreceptor function are still needed.     

Interaction between Heart Rate and Heart Rate Variability

Heart rate variability (HRV) is significantly associated with average heart rate (HR), therefore, HRV actually provides information on two quantities, that is, on HR and its variability. It is difficult to conclude which of these two plays a principal role in the HRV clinical value, or in other words, what is the HR contribution to the clinical significance of HRV. Moreover, the association between HRV and HR is both a physiological phenomenon and a mathematical one. The physiological HRV dependence on HR is determined by the autonomic nervous system activity, but the mathematical one is caused by the nonlinear relationship between RR interval and HR. By employing modification methods of the HRV and HR relationship, it is possible to investigate the HR contribution to the HRV clinical value. Recent studies have shown that the removal of the HR impact on HRV makes HRV more predictive for noncardiac death, however, the enhancement of this impact causes HRV to be a better predictor of cardiovascular mortality. Thus, HR seems to constitute a cardiovascular factor of the HRV predictive ability. HR also influences the reproducibility of HRV, therefore, HR changes should be considered when one compares HRV measurements in a given patient. This review summarizes methodological aspects of investigations of the HRV and HR interaction as well as latest observations concerning its clinical utility. The issues discussed in this article should also refer to any other heart rate dynamics analysis which indices are significantly associated with HR.     

Heart Rate and Heart Rate Variability in Normal Young Adults

Heart Rate and Heart Rate Variability. Introduction: The relationships between heart rate (HR) and HR variability (HRV) are not simple. Because both depend on the autonomic nervous system (ANS), they are not independent variables. Technically, the quantification of HRV is influenced by the duration of the cardiac cycles. The complexity of these relationships does not justify ignoring HK when studying HRV, as frequently occurs. Methods and Results: Using spectral and nonspectral methods, the HR and various normalized and non-normalized indices of HRV were studied in 24-hour recordings of a homogeneous cohort of seventeen 20-year-old healthy males. The HR-HRV relationships were appraised by analyzing the same data in two different ways. The 24 mean hourly values provide consistent information on the circadian behavior of the indices, while the average 24-hour individual data show a wide spectrum of normality. Combined approaches allow assessment of the direct impact of RR interval on HRV evaluation. The correlations between HR and normalized indices of HRV arc weaker in 24-hour individual data than in pooled hourly data of the same individuals. These correlations are close to 1 in the latter case, which does not mean that measuring HRV is simply another method of evaluating HR, but that normal physiology supposes a harmonious behavior of the various indices. When considered individually without normalization, the specific indices of vagal modulation (high-frequency band of the spectrum, short-term HR oscillations of the nonspectral analysis) consistently increase at night and diminish during the day. However, the low-frequency power, which supposedly reflects sympathetic influences, also increases at night, whereas more logically the longer HR oscillations would predominate during the day. Moreover, the selective analysis of HR oscillations during HR acceleration or decrease indicates that their behavior differs accordingly. Conclusion: We recommend that closer attention be paid to the complex relationships between HR and HRV. The strong correlations found in healthy subjects may reflect either the physiological harmony of ANS functions or simple redundancy. Their tendency to deteriorate in diseased hearts suggests that redundancy is not the cause and that abnormalities of ANS functions are not demonstrated by HRV analysis alone.     

正常人群的心率变异性分析

将１００４例正常人分三个年龄组进行短程（５ｍｉｎ）心率变异性（ＨＲＶ）分析。时域法的参数为平均心率标准差（ＨＲＳＤ），连续５ｍｉｎ节段平均正常ＲＲ间期标准差（ＳＤＡＮＮ），相邻ＲＲ间期差的均方根（ｒＭＳＳＤ），相邻ＲＲ间期差异≥５０ｍｓ的百分数（ＰＮＮ_（５０））；频域法的参数为极低频（ＶＬＦ）、低频（ＬＦ）、高频（ＨＦ）成分，总功率（ＴＰ）及ＬＦ／ＨＦ比值。各指标间做相关分析。结果：４５岁以上组ＨＲＳＤ、ＳＤＡＮＮ、ｒＭＳＳＤ、ＰＮＮ_（５０）、ＶＬＦ、ＬＦ、ＨＦ、ＴＰ均低于４５岁以下两组（Ｐ＜０．０５或＜０．０１）。ＳＤＡＮＮ、ｒＭＳＳＤ、ＰＮＮ_（５０）与ＨＦ呈高度正相关（ｒ＞０．７０，Ｐ＜０．０００１），其中以ＳＤＡＮＮ、ＰＮＮ_（５０）相关更好（ｒ＞０．７５，Ｐ＜０．００１），ＳＤＡＮＮ、ｒＭＳＳＤ、ＰＮＮ_（５０）间高度相关（ｒ＞０．８０，Ｐ＜０．０００１）。不同性别ＨＲＶ各参数相比无显著差异。提示：ＨＲＶ随年龄的增长而下降，以迷走神经张力下降为主；各指标中以ＳＤＡＮＮ、ｒＭＳＳＤ、ＰＮＮ_（５０）、ＨＦ能更好地反映迷走神经张力变化。     

运动和精神活动影响心率变异的研究进展

心率变异 (HRV)是评价心脏自主神经活性的可靠指标。在生理状态下 ,心脏受交感迷走神经平衡调节 ,而在运动、情绪变化时这种平衡调节被打破 ,表现为交感神经兴奋而迷走神经抑制。因此可通过 HRV分析探讨体力活动和精神活动过程中心脏自主神经张力改变的机理及异常改变的病理意义。1　体力活动对心率变异影响L ucini等 [1]发现健康人在开始大运动量活动 (如平板运动 )前 ,心脏自主神经就由静息时交感迷走神经相互平衡状态向运动时交感神经占优势的方向转化。健康人用其 1/ 4最大力量握拳时 ,归一化的低频值(L Fnu)比静息时 53± 2明显升…     

心率和心率变异性与心力衰竭及预后的相关性

目的　探讨心率及心率变异性与心力衰竭及预后的相关性。方法　入选2010年10月至2012年6月期间就诊宁夏医科大学总医院心内科的慢性充血性心力衰竭患者245例,根据住院期间平均静息心率水平分为3组：A组：50～70次/分;B组：71～90次/分;C组：＞90次/分;共随访1年,完成随访共230例。其中共有97例行动态心电图检查,按患者心功能分级分为Ⅱ级组、Ⅲ级组、Ⅳ级组,同时选择26例正常健康人为对照组。收集上述研究对象的心率变异性时域指标进行对比分析,包括正常RR间期标准差（SDNN）、5　min均值标准差（SDANN）、相邻RR间期相差＞50　ms的个数占总心跳数的百分比（PNN50）、全程相邻RR间期之差的平方根（RMSSD）。结果随着心率水平增加,随访终点射血分数明显降低,再住院率及病死率明显增加（P＜0.01）。不同心率水平心力衰竭患者Cox生存分析显示心率越快,生存率越低。心力衰竭组与对照组相比SDNN、SDANN、PNN50、RMSSD降低（P＜0.01或P＜0.05）,随着心力衰竭程度的加重,SDNN、SDANN、PNN50、RMSSD下降越明显（P＜0.01）。结论　心率越快,心力衰竭预后越差;心力衰竭患者存在心率变异性降低,心率变异性越低,心功能越差。     

慢性心力衰竭病人的心率变异性及左旋甲状腺素钠的干预作用

目的 探讨慢性心力衰竭（CHF）病人心率变异性（HRV）的变化。研究HRV各指标与CHF类型、原发病、心功能关系及左旋甲状腺素钠（优甲乐）对CHF病人HRV的影响。方法 选择CHF病人114例，分为左心衰竭组、右心衰竭组、全心衰竭组，并以38名健康对照者进行比较。记录每位个病人治疗前的HRV、慢性心力衰竭类型、原发病、心功能。对CHF114例中低三碘甲状腺原氨酸（T3）的60例CHF病人随机分为两组，每组30例。对照组给予常规抗心力衰竭治疗，治疗组在常规抗心力衰竭治疗基础上加服优甲乐50ug／d，口服。治疗前和治疗3个月后分别测定两组病人的HRV指标并进行比较；出院后随访半年，记录再住院率、病死率。结果 CHF病人24h总的NN间期标准差（SDNN）、24h总的NN间期平均值的标准差（SDANN）较正常对照组降低，且随着CHF心功能程度的加重而逐渐降低；与左心衰竭组、右心衰竭组比较，全心衰竭组SDNN、SDANN降低（P〈0.01）。治疗3个月后，治疗组的SDNN、SDANN均较治疗前及对照组明显提高（P〈0．05）。结论 病人HRV部分指标变化可作为判定严重程度的参考指标。各项HRV指标变化大小可能与病人的原发病无关，但部分似与CHF类型、心功能程度有关。在常规抗心力衰竭治疗的基础上，加用优甲乐治疗CHF，可提高病人HRV，增强疗效，改善预后。     

心率变异对甲状腺机能亢进患者自主神经功能的评价

采用短时采样的时域、频域法对１８例初诊甲状腺机能亢进（简称甲亢）患者（甲亢组）进行心率变异分析，并以１８例正常人作为对照（对照组），了解甲亢患者自主神经功能的改变。与对照组相比，甲亢组平均ＲＲ间期、ＲＲ平均值标准差、相邻ＲＲ间期差值的均方根、相邻ＲＲ间期相差＞５０ｍｓ占总心动周期数的百分比均明显降低（分别为５５４．５３±６７．７９ｍｓｖｓ８５８．３６±９０．４３ｍｓ、１６．４１±５．５０ｍｓｖｓ４３．０８±１１．０４ｍｓ、１１．３２±３．１６ｍｓｖｓ３７．４３±１０．１２ｍｓ、０．３３±０．５１％ｖｓ１５．２２±１２．８４％，Ｐ均＜０．００１）。极低频段成分明显升高、高频段（ＨＦ）成分明显降低（分别为３８．３２±８．６０ｍｓ２／Ｈｚｖｓ２５．１１±１０．７８ｍｓ２／Ｈｚ、１２．７７±７．０４ｍｓ２／Ｈｚｖｓ３５．６５±１５．０８ｍｓ２／Ｈｚ，Ｐ均＜０．００１）、低频段（ＬＦ）成分无明显改变（２７．１２±１１．３４ｍｓ２／Ｈｚｖｓ２９．６０±１０．３１ｍｓ２／Ｈｚ，Ｐ＞０．０５），ＬＦ／ＨＦ明显增高（２．７６±１．７１ｖｓ１．１７±１．０８，Ｐ＜０．００２），心率总功率谱密度无明显变化。提示甲亢患者不仅交感神?