原发性高血压伴急性脑梗死患者心率变异性与血压变异性分析

目的：探讨原发性高血压伴急性脑梗死患者的心率变异性（heart rate variability, HRV）和血压变异性（blood pressure variability,BPV）。方法收集原发性高血压合并急性脑梗死患者82例、单纯原发性高血压患者108例,进行动态心电图和动态血压同步测量,计算机自动计算 HRV 和 BPV 各指标。结果脑梗死组 HRV 各指标均低于单纯高血压组,且差异有统计学意义（P ＜0．05）;夜间血压下降率脑梗死组均低于单纯高血压组,BPV 各指标脑梗死组均高于单纯高血压组,其中夜间舒张压下降率、24 h 平均收缩压（24 h SBP）和24 h 收缩压变异系数（24 h SCV）两组差异有统计学意义（P ＜0．05）。结论与单纯原发性高血压患者相比,原发性高血压合并急性脑梗死患者自主神经功能受损明显。随访观察 HRV 和 BPV 指标的变化对高血压及高血压合并急性脑梗死患者的病情评估及改善预后有一定的临床意义。     

糖尿病对高血压患者动态血压及血压变异性的影响

目的 探讨2型糖尿病（T2DM）对原发性高血压（EH）患者动态血压（ambulatory blood pressure，ABP）及血压变异性（blood pressure variability，BPV）的影响。方法 选取36例单纯EH及33例合并T2DM的EH患者，行24hABP监测，对2组患者的ABP及BPV进行对比分析。结果 与单纯EH患者相比，合并T2DM的EH患者日间平均收缩压（dmSBP）（P〈0，05）、日间脉压（dmPP）（P〈0.01）、日间收缩压标准差（dSBPSD）（P〈0.01）及日间收缩压标准差变异系数（dSBPCV）（P〈0．05）显著增大。结论 T2DM加重EH患者心血管系统的结构与功能异常，引起ABP及BPV增大；改善其体内糖代谢状况，将有助于改善其心血管系统血流动力学，从而减少心血管并发症。     

高血压和非高血压2型糖尿病患者心率变异性、压力反射敏感性和血压变异性频谱分析鉴定心脏自主神经病变

目的采用心率变异性（HRV）、压力反射敏感性（BRS）和血压变异性（BPV）频谱方法了解高血压和非高血压T2DM患者心血管自主神经病变的诊断价值。方法119例T2DM患者和101例非糖尿病对照者分别分为高血压（HT）和非高血压（NHT）亚组,均进行HRV、BRS和BPV检测。结果DM组中HT和NHT亚组的TV.rri、VLF.rri、LF.rri和HF．rri均显著低于对照组。DM-HT组的Total．brs和HF．brs明显下降,BPV无改变;DM-NHT组的TV．bp和VLF．bp显著增加。结论糖尿病患者（无论有无HT）HRV下降,反映基础状态下心血管自主神经功能张力异常可能不受血压影响;DM合并HT患者BRS降低,提示DM合并HT可使心血管反射调节能力减退;无高血压的DM患者BPV增大,提示DM患者血压调定和稳态早期受损。     

老年2型糖尿病合并冠心病患者的心率变异性分析

目的探讨老年2型糖尿病（T2DM）合并冠心病（CHD）患者心率变异性（HRV）分析的临床意义。方法对44例老年T2DM患者按照有无合并CHD分为2组，20例健康人为对照组，进行HRV时域分析。结果单纯T2DM组和合并CHD组的HRV时域各项指标均低于对照组（P〈0．05，P〈0．01）；合并CHD组的大部分参数值亦低于单纯T2DM组（P〈0．05）。结论老年T2DM合并CHD会显著加重心脏自主神经功能损害，使心率变异性降低。HRV能较直观地评价老年T2DM患者的心血管功能状态，有助于早期筛选高危患者，预防心血管事件的发生。     

糖尿病对老年高血压患者动态血压及血压变异性的影响

目的探讨老年2型糖尿病患者中糖尿病对原发性高血压（高血压）患者的动态血压（ambulatory bloodpressure,ABP）及血压变异性（blood pressure variability,BPV）的影响。方法选取40例单纯高血压及42例65岁以上合并2型糖尿病的高血压患者,行24 h ABP监测,对2组患者的ABP及BPV进行对比分析。结果合并2型糖尿病的高血压患者日间平均收缩压（dmSBP）及夜间平均收缩压（nmSBP）高于单纯高血压患者,差异有统计学意义（P〈0.05或0.01）;合并2型糖尿病的高血压患者日间脉压（dmPP）、夜间脉压（nmPP）及24 h平均脉压差（24 h-mPP）均大于单纯高血压患者,差异有统计学意义（P〈0.05或0.01）;BPV方面,合并2型糖尿病的高血压患者日间收缩压标准差（dSBPSD）及日间收缩压标准差变异系数（dSBPCV）、夜间收缩压标准差（nSBPSD）及夜间收缩压标准差变异系数（nSBPCV）、24 h收缩压标准差（24 h-SBPSD）均显著高于单纯高血压患者,差异有统计学意义（P〈0.05或0.01）。结论年龄、高血压是老年2型糖尿病患者大血管病变的独立危险因素,2型糖尿病合并高血压时,ABP及BPV增大,心血管系统的结构与功能异常。改善糖代谢状况将有助于形成良好的代谢记忆,从而改善血流动力学,减少心血管并发症。     

2型糖尿病合并心血管疾病患者心率变异性分析

目的：研究糖尿病合并心血管疾病对心率变异性（HRV）的影响。方法：对44例糖尿病合并高血压、冠心病及48例单纯糖尿病患进行24小时心率变异时时域分析，同时与年龄、性别相当的62例正常人HRV资料进行比较。结果：（1）糖尿病患各项时域分析指标均较正常组降低（P＜0．05－＜0．01）；（2）与单纯糖尿病患比较，有心血管合并症的糖尿病患HRV参数中SDNN、SDANN、SDNN－index、rMSSD明显降低（P＜0．05－＜0．01）；（3）昼夜资料分析显示与正常组比较糖尿病患白天mR-R升高（P＜0．05），SDNN、rMSSD、PNN50显下降（P＜0．05－＜0．01），夜间各指标均明显降低（P＜0．05－＜0．01），合并高血压、冠心病的患除SDANN、PNN50外各指标下降更加显。提示糖尿病患的HRV分析有助于预测心脏事件的发生。     

老年单纯收缩期高血压患者心率变异性分析

目的 探讨老年单纯收缩期高血压（EISH）患者心率变异性（HRV）时域指标变化，了解血压参数与HRV时域指标关系。方法 对32例老年单纯收缩期高血压患者，30例老年舒张期高血压患者，28例老年收缩、舒张双期高血压患者和30例健康老年人行24h动态心电图，检查、了解其24hHRV的时域指标。并对EISH患者的血压参数和HRV时域指标进行相关分析。结果 ①EISH患者与老年健康对照组比较SDNN、RMSSD、PNN50显著降低（P〈0．01，P〈0．01，P〈0．05）。②EISH患者与舒张期高血压组比较SDNN、RMSSD、PNN50显著降低（P〈0．01，P〈0．05，P〈0．01）。③EISH组患者收缩压与SDNN、PNN50、SDANN呈负相关（r=-0．865，P〈0．01；r=-0．923，P〈0．01；r=-0．878，P〈0．01）。平均动脉压（MAP-）与SDNN、PNN50、SDANN呈负相关（r=-0．461，P〈0．01；r=-0．481，P〈0．01；r=-0．458，P〈0．01）。结论 收缩期高血压患者较舒张期高血压患者自主神经功能损害更加明显。     

比较不同时间服用缬沙坦对高血压患者血压变异性的影响

目的比较不同时间服用缬沙坦及苯磺酸氨氯地平片对原发性高血压（高血压）患者血压变异性（bloodpressurevariability,BPV）的影响。方法采用随机数字法将120例轻一中度高血压患者分成3组,分别为日间口服缬沙坦组、夜间口服缬沙坦组、日间口服苯磺酸氨氯地平组,治疗前、后进行24h动态血压监测。以动态血压变异标准差作为血压变异性指标,比较3个月后3种治疗方案对血压及血压变异性的影响。结果3种治疗方案均能有效降低血压,与治疗前比较差异有统计学意义（P〈0．05）。在控制BPV方面,日间口服缬沙坦组的BPV改善不明显,与治疗前比较差异无统计学意义（P〉0．05）;与治疗前比较,夜间口服缬沙坦组[收缩压变异性：（11±3）mmHg眠（15±4）nlmHg（1mmHg=0．133kPa）,P〈0．05;舒张压变异性：（7±2）mmHgVS．（10±4）mmHg,P〈0．05]和苯磺酸氨氯地平组[收缩压变异性：（10±3）mmHgIJS．（16±3）mmHg,P〈0．05;舒张压变异性：（6±2）mmHgVS．（11±2）mmHg,P〈0．05]的24h动态血压变异性降低,差异有统计学意义;苯磺酸氨氯地平组在改善BPV方面仍优于夜间口服缬沙坦组,差异有统计学意义（P〈0．01）。结论与日间服药相比,夜间服用缬沙坦能更有效改善血压变异性。     

高血压伴糖尿病患者的动态血压变异性改变

对单纯原发性高血压患者96例、高血压合并糖尿病患者32例及对照组5 6例,分别动态测量血压24h,计算血压变异性,并分别进行对照研究。结果：①高血压组与对照组比较：24hSBP、24hSBP、dSBP、dDBP、nSBP、nDBP及SPBp、DPBd、DBPp均有显著性差异（P＜0．01）,24hSBP、24hSBP、dSBPv有明显差异（P＜0．05）;②高血压合并糖尿病组与对照组比较：24hSBP、24hSBP、dSBP、nSBP、nDBP、SBPp、DBPp存在显著差异（P＜0．01）,dSBPv、dDBP、DBPd存在明显差异（P＜0．05）;③高血压组与高血压合并糖尿病组比较：24hSBPv、24hDBPv、dDBP、DBPd减低,显示动态血压的变异性减低,但统计学无明显差异。认为高血压合并糖尿病患者血压变异性降低,可能与糖尿病自主神经病变相关,使正常的血压节律消失。     

高血压合并2型糖尿病患者的心率变异性分析

目的探讨心率变异性对早期发现高血压及高血压合并2型糖尿病心脏植物神经病变的意义。方法选择21例高血压病人、15例高血压合并2型糖尿病病人和20例健康人进行24h动态心电图记录，分析比较。结果高血压组、高血压合并2型糖尿病组的SDNN、SDANN、SDNNindex、rMMSD、PNN50较正常对照组均有明显变化（P〈0．05）；高血压合并2型糖尿病组较高血压组也有明显变化（P〈0．05）。结论心率变异性可以作为早期发现高血压或合并2型糖尿病患者心脏植物神经损害的一个有效的无创方法。     

Heart rate variability

Reduced heart rate variability carries an adverse prognosis in patients who have survived an acute myocardial infarction. This article reviews the physiology, technical problems of assessment, and clinical relevance of heart rate variability. The sympathovagal influence and the clinical assessment of heart rate variability are discussed. Methods measuring heart rate variability are classified into four groups, and the advantages and disadvantages of each group are described. Concentration is on risk stratification of postmyocardial infarction patients. The evidence suggests that heart rate variability is the single most important predictor of those patients who are at high risk of sudden death or serious ventricular arrhythmias.     

不同程度冠心病患者QT变异和QT变异指数的观察

目的探讨冠心病患者的QT变异(QTV)和病变程度的相关性。方法122例冠心病患者(75例劳累性心绞痛患者,47例非ST段抬高性心肌梗死患者)和55例正常对照组,在保持日常生活起居的情况下佩戴12导联动态心电图监测仪,计算机辅助下自动测量QT间期,计算相应时间段的QT间期均值(QTm)、QTV、HR间期均值(HRm)、HR间期变异(HRV)和QT变异指数(QTVI)。同时采用时域法(SDNN)和频域法(LF、HF)分析心率变异性。结果①正常对照组24hLF/HF、HF、QTV均呈昼夜节律性变化。②非ST段抬高性心肌梗死组、劳累性心绞痛组和正常对照组之间的QTV差异显著(29.2±13.6ms、26.8±13.1ms、21.7±12.4ms,P<0.05)。③正常对照组QTV与SDNN存在负相关,相关系数为-0.40,P<0.05。而劳累性心绞痛组和非ST段抬高性心肌梗死组的QTV与SDNN无相关性,P>0.05。④QTV、QTVI随着冠状动脉病变程度的加重而变大,且各组比较有显著性差异,P<0.05。结论QTV与冠状动脉病变程度有关,QTV的变化不仅依赖于自主神经,而且是许多不同病理生理因素作用的结果,在心肌缺血的情况下,能更直接地反映心肌的代谢和病变状态。     

Relationship of QT interval variability to heart rate and RR interval variability

The study investigated whether the beat-to-beat QT interval variability relationship to the mean heart rate and the RR interval variability depended on the cardiovascular autonomic status changed by postural positioning. Repeated long-term 12-lead Holter recordings were obtained from 352 healthy subjects (mean age 32.7 ± 9.1 years, 176 females) while they underwent postural provocative tests involving supine, unsupported sitting and unsupported standing positions. Each recording was processed as a sequence of overlapping 10-second segments. In each segment, the mean RR interval, the coefficients of variance of the RR intervals (RRCV) and the QT intervals (QTCV) were obtained. In each subject, these characteristics, corresponding to different postural positions, were firstly averaged and secondly used to obtain within-subject correlation coefficients between the different characteristics at different postural positions. While the within-subject means of RRCV generally decreased when changing the position from supine to sitting and to standing (4.53 ± 1.95%, 4.12 ± 1.51% and 3.26 ± 1.56% in females and 3.99 ± 1.44%, 4.00 ± 1.24% and 3.53 ± 1.32% in males respectively), the means of QTCV systematically increased during these position changes (0.96 ± 0.40%, 1.30 ± 0.56% and 1.88 ± 1.46% in females and 0.85 ± 0.30%, 1.13 ± 0.41% and 1.41 ± 0.59% in males, respectively). The intra-subject relationship between QTCV, RRCV and mean RR intervals was highly dependent on postural positions. The study concludes that no universally applicable normalization of the QT interval variability for the heart rate and/or the RR interval variability should be assumed. In future studies of the QT variability, it seems preferable to report on the absolute values of QT variability, RR variability and mean heart rate separately.     

Intraindividual variability in electrocardiograms

The electrocardiogram (ECG) can be affected by intraindividual variations from various sources that may confuse the diagnosis of the underlying cardiac condition and impair the accuracy of ECG interpretation. Intraindividual variability is a hindrance in serial ECG analysis, where ECGs of the same individual, but taken at different times, are compared. Two sources of intraindividual variability can be distinguished as follows: variability related to the technical circumstances during ECG recording (technical sources) and nonpathologic biologic variability (biological sources). Among the technical sources, variation in electrode positioning between recordings is the most confusing. Of the biological sources, respiratory variations are effective at any time scale, but the most important are age and weight that work on prolonged time scales. Technical problems are best prevented by rigorously sticking to a standard acquisition protocol. Criteria can be adapted to changing circumstances (age, weight), and by computer modeling, it may be possible to correct the ECG diagnosis for some sources of intraindividual variability.     

Species selection on variability

Most analyses of species selection require emergent, as opposed to aggregate, characters at the species level. This "emergent character" approach tends to focus on the search for adaptations at the species level. Such an approach seems to banish the most potent evolutionary property of populations--variability itself--from arguments about species selection (for variation is an aggregate character). We wish, instead, to extend the legitimate domain of species selection to aggregate characters. This extension of selection theory to the species level will concentrate, instead, on the relation between fitness and the species character, whether aggregate or emergent. Examination of the role of genetic variability in the long-term evolution of clades illustrates the cogency of broadening the definition of species selection to include aggregate characters. We reinterpret, in this light, a classic case presented in support of species selection. As originally presented, the species selection explanation of volutid neogastropod evolution was vulnerable to a counterinterpretation at the organism level. Once this case is recast within a definition of species selection that reflects the essential structure and broad applicability of hierarchical selection models, the organism-level reinterpretation of variability loses its force. We conclude that species selection on variability is a major force of macroevolution.     

Factors affecting circadian variability

Several unfavorable cardiovascular events show a well-defined pattern in their occurrence throughout the day. Myocardial infarction and ischemia, sudden cardiac death and stroke occur with greater frequency in the morning hours after awakening. Multiple biologic functions such as blood pressure, heart rate, sympathetic neurotransmission, vascular tone, platelet aggregability, and coagulation parameters also show a diurnal variation and appear to contribute to adverse cardiac outcomes. Recent studies have emphasized the importance of 24 h control in decreasing cardiovascular risk. The renin-angiotensin system (RAS), through the important effector peptide, angiotensin II (Ang II), has potent effects on blood pressure, salt and water homeostasis, and target-organ damage. Inhibiting the RAS consequently becomes an important therapeutic avenue for treating hypertension and target-organ damage. Ang II receptor antagonists selectively compete with the binding of Ang II to the Ang II type 1 receptor and, by inhibiting the multiple activities mediated by Ang II at this receptor, may confer cardiovascular benefits additional to that of blood pressure control. Ang II receptor antagonists with an intrinsically long duration of action that produce smooth, sustained antihypertensive activity over the dosing period provide a similar 24 h benefit of Ang II inhibition.