Reproducibility of non-invasive measurement and of short-term variability of blood pressure and heart rate in healthy volunteers.

1. Spectral analyses of blood pressure and heart rate oscillations are increasingly used to assess the influences of diseases and drugs on the autonomic nervous system. Such influences can only be interpreted in view of the spontaneous variability of these oscillations. We therefore studied the reproducibility of power spectral analyses of blood pressure and heart rate fluctuations measured by a non-invasive finger plethysmographic method in 24 healthy volunteers. 2. Intra-observer reproducibility was assessed from measurements obtained on 3 consecutive days and 1 month later in each subject. Inter-observer reproducibility was assessed by comparing measurements made by two observers on one occasion. 3. There was no significant difference in standard haemodynamic and spectral analysis parameters (low frequency: 60-130 mHz and high frequency: respiration rate +/- 30 mHz) measured on 3 consecutive days and 1 month later in each subject. The standard deviation of differences between systolic blood pressure or heart rate oscillations on different occasions was in the 150-200 and 50-100 mm Hg Hz-1/2 or beats min-1 Hz-1/2 range for low frequency and high frequency oscillations respectively. Similar results were found when inter-observer reproducibility was considered. 4. From these results, we derived a sample-size table giving the number of subjects to be included in studies of cross-over or parallel design in order to detect a non-random difference in spectral analysis parameters.(ABSTRACT TRUNCATED AT 250 WORDS)     

Correlation between body mass index and blood pressure indices, handgrip strength and handgrip endurance in underweight, normal weight and overweight adolescents

In the present study, we investigated the correlation between body mass index (BMI), blood pressure (BP) indices and indices of physical fitness in apparently healthy subjects aged 14-18 years. We obtained data from 145 (105 males and 40 females) and assessed the correlation between BMI, and heart rate, systolic pressure (SP), diastolic pressure (DP), pulse pressure (PP), mean arterial pressure (MP), rate-pressure product, endurance in the 40 mm Hg test, handgrip strength (HGS), and handgrip endurance. Subjects with BMI <18.5 kg/m2, 18.5-25 kg/m2 and >25 kg/m2 were classed as underweight (65 males and 9 females), normal weight (27 males and 20 females), and overweight (13 males and 11 females) respectively. In view of gender differences in autonomic regulation, data of male and female subjects were analyzed separately. We used analysis of variance to compare differences between the three groups. Correlation between BMI and other indices was tested using Pearson's correlation coefficient. A P value <0.05 was considered statistically significant Both SP and DP were highest in overweight and least in underweight male subjects (P<0.05 for both), whereas in females, differences in DP alone were statistically significant (P<0.05). In underweight male subjects, there was a positive correlation between BMI and SP, DP, PP, MP and HGS (P<0.05 for all). There was a positive correlation between BMI and SP in overweight male subjects (r = 0.5 P = 0.07, n = 13). A positive correlation was observed between BMI and rate-pressure product (r = 0.5, P = 0.45, n = 11) and BMI and HGS (r = 0.6, P = 0.05, n = 11) in overweight females. Our observations indicate that there are gender differences in the correlation between BMI and BP indices especially in underweight and overweight subjects. The observed differences between the three groups and gender differences in correlation between BMI and BP indices may be due to differences in autonomic function and or energy metabolism.     

Effect of imipramine treatment on changes in heart rate and blood pressure during postural and isometric handgrip tests

Summary Postural and isometric handgrip tests were performed on nine patients with panic disorder and 13 patients with major depression before and after treatment with imipramine for a mean duration of 10 weeks.There were significant increases in resting supine heart rate (HR), systolic, diastolic and mean blood pressures (SBP, DBP, MBP) after treatment. There were significant increases in HR and DBP after standing from supine posture before treatment, and after treatment, there was a significant enhancement of this tachycardia. The decrease of heart rate during the change from standing to supine posture before treatment significantly decreased further after imipramine treatment. Decreases in SBP and DBP during the change from standing to supine posture were significantly smaller during the post treatment condition. Increases in SBP during the standing isometric exercise test were smaller after treatment.These findings suggest abnormal orthostatic reflexes secondary to an altered adrenergic function and/or cholinergic supersensitivity after treatment with imipramine.     

The effects of sildenafil on heart rate variability in healthy subjects

The effects of sildenafil on heart rate variability were investigated in 20 healthy male subjects aged 24 (21 to 32) years (median; range). Subjects orally received single 100-mg doses of sildenafil and placebo under randomized double-blind crossover conditions on 2 separate study days. Time domain measures of heart rate variability were assessed under conditions of relaxed rest, metronomic breathing (6 cycles per minute), and bicycle ergometry before administration of sildenafil and placebo as well as 60 minutes afterwards. Sildenafil did not alter heart rate nor heart rate variability to a significant extent (P > 0.05).     

The effects of cyclosidimine, a peripheral vasodilator drug, on blood pressure and heart rate in healthy subjects

Cyclosidimine is a new vasodilator drug with a direct action on vascular smooth muscle. Oral administration of 2.5, 5.0 and 7.5 mg in five normal volunteers had no effect on blood pressure in the supine position but reduced systolic and diastolic pressure in the erect position. In both positions heart rate was significantly greater after cyclosidimine than after placebo. Propranolol prevented the increases in heart rate produced by cyclosidimine which then produced greater reductions in blood pressure.     

高血压患者心率变异性与血压变异性分析

目的 分析高血压患者心率变异性与血压变异性的关系.方法 对高血压患者120例按1999年WHO/ISH高血压诊断标准分为:1级高血压40例,2级高血压40例,3级高血压40例,另设正常血压对照组40例,均同时检测心率变异性与血压变异性.结果 各组间心率变异性差异有统计学意义(P<0.05或P<0.01),随组间血压增高,心率变异性趋向减少;各组间血压变异性差异有统计学意义(P<0.01),随组间血压增高,血压变异性趋向增大.结论 高血压患者血压分级与心率变异性和血压变异性有一定关系.     

Differential effects of enalapril and hydralazine on short-term variability of blood pressure and heart rate in rats.

Using a spectral procedure, we studied the acute and chronic effects of enalapril and hydralazine on the variability of blood pressure (BP) and heart rate (HR) in conscious Wistar rats. In the acute protocol, rats received two injections 25 min apart (saline followed by enalaprilic acid or hydralazine hydrochloride). In the chronic protocol, animals received oral enalapril maleate, hydralazine hydrochloride, or distilled water. A 5-min recording session was initiated on day 12. Acute enalapril and hydralazine amplified the low-frequency (LF) component of the systolic BP (SBP) spectrum. Chronic enalapril reduced the variability of BP, as indicated by the lower variance in SBP distribution. Chronic enalapril preferentially reduced the amplitude of the 400-mHz oscillations of SBP. Acute administration of enalapril or hydralazine resulted in BP variability profiles, suggesting a reflexly mediated vascular sympathetic activation. In contrast, chronic angiotensin-converting enzyme (ACE) blockade with enalapril caused a significant decrease in the LF oscillations of BP. This could reflect a reduced sympathetic outflow to vascular smooth muscles.     

Vagal and sympathetic contributions to the heart rate at rest and during isometric and dynamic exercise in young healthy men

Six young healthy males received on four different occasions 0.4 mg/kg i.v. of propranolol. 0.04 mg/kg i.v. of atropine, atropine following propranolol or saline. heart rate and blood pressure were recorded at rest (supine, sitting, and standing) and during isometric and dynamic exercise. On the basis of heart rate changes under the influence of drugs, the sympathetic contribution to heart rate was 25% at supine rest, 33% in the standing position, 45% during handgrip, and 74% during bicycle exercise that raised heart rate to 153/min. These results suggest that with increasing muscular activity the contribution of parasympathetic tone to heart rate decreases from about 75% at supine rest to about 25% at submaximal exercise. Extrapolation of the heart rate plots indicate that parasympathetic tone is virtually abolished at exercise loads resulting in a heart rate of about 200 beats/min.     

Correlation between plasma clozapine concentration and heart rate variability in schizophrenic patients

 Forty schizophrenic patients treated with 50–600 mg/day of clozapine as monotherapy and 40 normal control subjects were tested for heart rate variability (HRV) which is mediated by the vagus nerve using acetylcholine as neurotransmitter. As compared to the control subjects, the patients showed essentially reduced HRV parameters which were negatively correlated with the plasma clozapine levels. Therefore, clozapine’s anticholinergic effect is correlated to the plasma clozapine level when measured by the decrease of HRV. We suggest that HRV data might be useful as a predictor for plasma clozapine levels. Received: 9 April 1997/Final version: 21 July 1997     

Association between heart rate variability indices and features of spontaneous ventricular tachyarrhythmias in mice

Direct evidence is limited for the association between heart rate variability (HRV) indices and ventricular tachyarrhythmias (VTAs). While galectin-3 (Gal-3) is regarded as a causal factor for cardiac remodelling and a biomarker for arrhythmias, its regulation on VTAs and HVR is unknown. Using aged transgenic (TG) mice with cardiac overexpression of β₂-adrenoceptors and spontaneous VTAs, we studied whether changes in HRV indices correlated with the severity of VTAs, and whether Gal-3 gene knockout (KO) in TG mice might limit VTA. Body-surface ECG was recorded (10-minute period) in 9- to 10-month-old mice of non-transgenic (nTG), TG and TG × Gal-3 knockout (TG/KO). Time-domain, frequency-domain and nonlinear-domain HRV indices were calculated using the R-R intervals extracted from ECG signals and compared with frequency of VTAs. TG and TG/KO mice developed frequent VTAs and showed significant changes in certain time-domain and nonlinear-domain HRV indices relative to nTG mice. The severity of VTAs in TG and TG/KO mice in combination, estimated by VTA counts and arrhythmia score, was significantly correlated with certain time-domain and nonlinear-domain HRV indices. In conclusion, significant changes in HRV indices were evident and correlated with the severity of spontaneous VTAs in TG mice. The frequency of VTA and HRV indices were largely comparable between TG and TG/KO mice. Deletion of Gal-3 in TG mice altered certain HRV indices implying influence by neuronally localized Gal-3 on autonomic nervous activity.     

血压及心率变异性对急性心肌梗死后患者预后价值的研究

目的　研究急性心肌梗死后患者心率变异性 (HRV)、血压变异性 (BPV)的改变 ,评价 HRV及BPV对患者远期恶性心律失常及心脏性猝死的预测价值 ,探讨 BPV预测价值的临床意义。方法　 6 8例急性心肌梗死后行 2 4 h动态心电血压监测检查的患者 ,根据动态心电图检查结果分为非心律失常组及心律失常组 ,记录非心律失常组 HRV、BPV各值及心律失常组的 BPV各值 ,并与 19名正常对照组的 HRV、BPV值相比较。全部患者平均随访 12个月。比较两组发生恶性心脏事件及猝死者与未发生者 HRV、BPV改变情况 ,分别评价心律失常组 BPV,非心律失常组 BPV、H RV各自及两者结合的预测敏感度、特异度。结果　与正常对照组比较 ,急性心肌梗死后患者 HRV各值减小 ,BPV各值增大。在随访期内非心律失常组发生心脏事件 4例 ,心律失常组发生 3例。以 SDNN<5 0 ms及 DSD夜 >8m m Hg为指标 ,非心律失常组 HRV预测的敏感度为 75 % ,特异度为 87% ,BPV预测的敏感度为 5 0 % ,特异度 77% ,两者结合预测的敏感度、特异度分别为 5 0 % ,97%。心律失常组以 DSD夜>8mm Hg为指标预测的敏感度、特异度分别为 6 7% ,74 %。结论　与 HRV相比 BPV也是一个较好的心肌梗死预后指标 ,BPV与 H RV两者结合可以显著提高预测价值。 BPV对心肌梗死后合并心律失?     

老年与青年高血压病患者脉压和血压变异性比较

目的 比较老年和青年高血压病患者动态血压的差异,为老年高血压病患者的治疗提供依据.方法 我院高血压科就诊的83例2周内未服药的高血压病患者,60岁≤年龄＜80岁患者40例作为老年组,18岁≤年龄≤30岁患者43例作为青年组.2组患者均进行24 h动态血压监测,并比较结果.结果 老年高血压组的动态脉压、动态脉压指数和24h收缩压变异系数明显高于青年高血压组[(61±12) mm Hg(1 mm Hg=0.133 kPa)比(52 ±9)mm Hg,(0.44±0.07)比(0.37±0.06),(11±2)％比(8±2)％,均P＜0.01];24 h平均舒张压和24h平均心率明显低于青年高血压组[(79±10) mm Hg比(88±12)mm Hg,(69±8)次/mint比(74±9)次/min,均P＜0.01].结论 老年高血压病患者主要以动态脉压增大和24h收缩压变异性升高为特点;而青年患者以24h平均舒张压升高为主.因此,临床对老年高血压病患者进行降压治疗时,选择的药物不仅要有效降低平均收缩压水平,还要改善脉压和血压变异性.     

脑梗死合并高血压患者血压变异性、血压晨峰与动脉粥样硬化的相关性

目的 探讨脑梗死合并高血压患者血压变异性、血压晨峰与动脉粥样硬化的相关性.方法 选取2015年1月至2016年8月住院的脑梗死合并高血压患者132例进行颈部彩色多普勒超声检查,根据血管内膜中层厚度(IMT)分为IMT正常组20例,IMT增厚组56例,IMT斑块组56例,后2组判定为颈动脉粥样硬化.另外,根据24 h动态血压监测结果将132例患者分为非晨峰组49例和晨峰组83例.测定各组血脂、24 h平均收缩压(24 h SBP)、24 h平均舒张压(24 h DBP)、日间平均收缩压(dSBP)、日间平均舒张压(dDBP)、夜间平均收缩压(nSBP)、夜间平均舒张压(nDBP)、血压变异性、血压晨峰及神经功能缺损程度评分(NIHSS)、日常生活能力评分(BI).结果 IMT正常组、IMT增厚组、IMT斑块组TG、TC、LDL-C、HDL-C、ApoA、ApoB、Hcy、hs-CRP、24 h SBP、24 h DBP、dSBP、dDBP、nSBP、nDBP、24 h SBPV、dSBPV、血压晨峰检出率、NIHSS、BI评分比较差异均有统计学意义(P<0?.05).结论 脑梗死合并高血压患者血脂、Hcy、hs-CRP、24 h SBPV、dSBPV、血压晨峰与动脉粥样硬化有关,是导致动脉粥样硬化发生发展的独立危险因素.     

针刺治疗对原发性高血压患者血压变异性和心率变异性的影响

目的：探讨针刺治疗对原发性高血压患者血压变异性和心率变异性的影响。方法选择符合条件的60例原发性高血压患者进行针刺治疗,疗程为30 d,采用自身前后对照,分别于治疗前后完善24 h动态血压及24 h动态心电图检查。结果针刺治疗后血压变异性各指标（24 h平均收缩压、24 h平均舒张压、24 h收缩压标准差、24 h舒张压标准差、白昼收缩压标准差、白昼舒张压标准差、夜间收缩压标准差、夜间舒张压标准差）均较治疗前降低,差异具有统计学意义（ P＜0．05）;心率变异性各指标（连续RR间期标准差、平均5 min RR间期标准差、平均5 min RR间期标准差的平均值、连续RR间期差值的均方根值、相邻RR间期大于50 ms的百分数）均较治疗前有所改善,差异具有统计学意义（ P＜0．05）。结论针刺治疗能显著降低原发性高血压患者的血压变异性,改善心率变异性,从而可能改善高血压患者的靶器官损害。     

伊贝沙坦对原发性高血压的疗效及心率变异性的影响

目的 :观察伊贝沙坦对原发性高血压 (EH)的疗效及心率变异性的变化。方法 :原发性高血压患者 40例每日口服伊贝沙坦 1 5 0～ 3 0 0mg,共 8wk。观察血压变化 ,记录用药前后 2 4h动态心电图 ,分析心率变异 (HRV)时域和频域指标 ,并与 3 5例健康对照组比较。结果 :①EH患者应用伊贝沙坦后收缩压 (SBP)和舒张压 (DBP)由 2 1 .62± 0 .47/1 2 .0 1±0 .3 2kPa分别下降至 1 8.9± 0 .3 2 /8.0 1± 2 .3 5kPa,有效率达 73 .1 %。②与对照组相比 ,EH患者相邻正常RR间期标准差 (SDNN) ,正常相邻RR间期差值 (RMSSD) ,相邻正常RR间期差值大于 5 0ms的窦性心律 (PNN50 ) ,高频功率 (HF)明显下降 ,低频功率(LF)不变 ,低频功率 /高频功率 (LF/HF)值增加。应用伊贝沙坦后 ,SDNN、RMSSD、PNN50 、HF增加 ,LF/HF值降低。结论 :原发性高血压患者存在HRV下降 ,而伊贝沙坦在有效降低血压同时提高HRV ,改善自主神经功能失衡。     

室性早搏后心率变化与临床诊断相关性的研究

目的研究室性早搏后心率变化情况与疾病严重程度的相关性并探讨其临床应用价值。方法测定152例奎陛早搏患者奎陛早搏后窦性心率加速即震荡初始（TO）、窦性心率减速即震荡斜率（TS）以及心率是否相等。结果高血压、心肌炎及无器质性心脏病患者TO和／或鸭异常率较低，而冠状动脉粥样硬化性心脏病（冠心病）患者异常率较高，3者与冠心病患者比较差异有统计学意义（P〈0．05）；11例冠心病病情危重患者室性早搏后心率相等，余141例患者室性早搏后心率均不等。结论室性早搏后心率变化的测定对心脏疾病患者病情危重程度有一定的预测价值。