Heart Rate Variability and Major Arrhythmic Events in Patients with Idiopathic Dilated Cardiomyopathy

This prospective study of 71 patients with idiopathic dilated cardiomyopathy (IDC) and preserved sinus rhythm was designed to evaluate the relation between heart rate variability (HRV) and subsequent major arrhythmic events. Standard time- and frequency-domain HRV parameters were obtained from analysis of 24-hour Holter ECG recordings. During a mean follow-up of 15 ± 5 months, major arrhythmic events including sustained ventricular tachycardia, ventricular fibrillation, and sudden cardiac death occurred in 10 of the 71 study patients (14%). Neither time- nor frequency-domain indices of HRV differed significantly between patients with and patients without subsequent major arrhythmic events. However, there was a trend toward a lower standard deviation of the average normal RR interval for all 5-minute segments of the 24-hour recording (68 ± 17 ms vs 80 ± 31 ms; P = 0.06) in patients with major arrhythmic events. In addition, the percentage of adjacent normal RR intervals differing > 50 ms over the recording period tended to be lower in patients with major arrhythmic events (6%± 3% vs 9%± 6%; P = 0.08). Our results indicate a tendency toward attenuated parasympathetic activity in IDC patients with subsequent major arrhythmic events compared to arrhythmia-free patients. Larger studies with longer follow-up periods are necessary to clarify the role of HRV measurements for arrhythmia risk prediction in patients with IDC.     

Evolution of Cardiac Autonomic Nervous Activity Indices in Patients Presenting with Transient Left Ventricular Apical Ballooning

Backround: Transient left ventricular (LV) apical ballooning (AB) is characterized by a rapidly reversible, acute LV systolic dysfunction, triggered by physical or emotional stress. Despite observations strongly suggesting catecholamine-mediated myocardial stunning due to enhanced sympathetic activity, the early time course of heart rate variability (HRV) has not been described.
Methods: We prospectively enrolled 39 consecutive patients (median age = 68 years, range 35–85 years, 38 women) with LV AB. Indices of HRV were extracted from 24-hour ambulatory electrocardiograms on the day of hospital admission, on days 2 and 3, and 3 months after the hospitalization.
Results: Within 48 hours after hospital admission, the indices of HRV were markedly depressed (standard deviation of normal-to-normal [NN] intervals [SDNN] 89.6 ± 19.9 ms; mean standard deviation of NN intervals for 5-minute segments [SDNNi] 37.8 ± 6.2 ms; root mean square of consecutive difference of normal-to-normal intervals [rMSSD] 23.0 ± 9 ms; standard deviation of the averages of NN intervals for all 5-minute segments [SDANN] 70.1 ± 18.0 ms; geometric triangular index [TI] 23.7 ± 5.9 ms), recovered in the subacute phase and had normalized at 3 months follow-up (SDNN 124.7 ± 24 ms; SDNNi 47.1 ± 5.7 ms; rMSSD 31.1 ± 10.5 ms; SDANN 118.5 ± 27 ms; TI 31.2 ± 8 ms; all P < 0.05). Mean RR-interval increased from 845 ± 121 ms on day 1, to 929 ± 84 ms at 3 months (P = 0.06).
Conclusions: A marked depression of cardiac parasympathetic activity was observed in the acute phase of LV AB, followed by recovery of autonomic modulation between the subacute and the chronic phases. The rapid return of parasympathetic function may partially explain the favorable outcomes of patients presenting with LV AB.     

RR Variability and Baroreflex Sensitivity in Patients with Ventricular Tachycardia Associated with Normal Heart and Patients with Ischemic Heart Disease

Recent studies have suggested that disordered autonomic function, particularly the loss of protective vagal reflexes are associated with an increased incidence of arrhythmic deaths following myocardial infarction (MI). Heart rate variability (HRV) and baroreflex sensitivity (BRS) are measures of myocardial autonomic function and predict arrhythmic deaths post-Mi. Patients with ventricular tachycardia associated with a “normal heart” frequently have exercise-induced arrhythmia suggesting that the autonomic nervous system is important in the genesis of this form of ventricular tachycardia (VT). This study examines HRV and BRS in patients with VT associated with a “normal heart” and compares these values to patients post-Mi with and without evidence of arrhythmia. Twenty patients with VT associated with a “normal heart,” 16 patients with MI but without arrhythmia on follow-up, and 11 patients with MI and VT on follow-up were studied. HRV was measured from 24-hour Holter recordings and BRS was measured from plots of change in systolic blood pressure versus change in heart rate following an intravenous injection of 0.4–0.6 mg phenylephrine. HRV was significantly higher in the patients with VT associated with a normal heart (34.2 ± 10.8 msec) compared to the patients post-Mi, without (23.7 ± 6.7 msec) and with (14.8 ± 3.8 msec) arrhythmia (F = 9.2, P < 0.001) and these differences were unaffected by adjustment for age. Baroreflex sensitivity was also higher in patients with VT associated with a “normal heart” (10.1 ± 6.8 msec/mmHg) compared to patients post-Mi, without (6.1 ± 3.2 msec/mmHg) and with 3.2 ± 3.1 msec/mmHg) arrhythmia, (F = 7.2, P < 0.02), though statistical significance was lost after adjustment for age (F = 1.2, P = 0.3). We conclude that patients with VT associated with “normal hearts” have HRV and BRS that is higher than in patients post-MI. Alterations of autonomic tone are, therefore, unlikely to be important in VT associated with a “normal heart,” whereas these appear to be important in patients with arrhythmic events post-MI.     

Consistency of multicenter measurements of heart rate variability in survivors of acute myocardial infarction

Heart rate variability (HRV) analysis from 24-hour ambulatory ECG has been widely used in risk stratification of patients after myocardial infarction (MI). The accuracy of HRV assessment is known to potentially vary when different commercial systems are used. However, the consistency of HRV measurements has never been fully investigated. Twenty-six post-MI patients (mean age 59 +/- 8 years, 22 men) were studied, of whom 13 succumbed to sudden cardiac death (SCD) within 1 year and 13 remained alive for at least 3 years (MI survivors). Each patient had a 24-hour Holter ECG recorded before hospital discharge. HRV analysis was performed four times from the same recordings using three different Holter tape analysis systems (Marquette, Reynolds, and CardioData) by four independent operators (CardioData system was used twice, once in the United Kingdom and once in the United States). Mean normal-to-normal RR intervals (mNN) and 3 HRV parameters (SDNN, RMSSD, and HRV triangular index [HRVi]) were derived from each recording. The consistency of mNN and HRV measurements was evaluated by coefficient of variance (CV) and by the Bland-Altman method. The results demonstrated that (1) all indices measured by different systems were statistically similar (P = NS) except the measurement of RMSSD (P = 0.01), (2) the measurements of mNN were highly reproducible with a maximum mean difference of 1.8 +/- 13.8 ms and maximum limits of agreement from -14.6 to +15.6 ms. The maximum mean differences were--1.8 +/- 1.4 unit and 4.4 +/- 9.6 ms for HRVi and SDNN, respectively, and RMSSD was less reproducible with a maximum mean difference of--11.1 +/- 11.5 ms, and limits of agreement from -16.2 to +9.6 ms; and (3) the consistency of mNN (CV 0.9% +/- 0.9%) was significantly higher than that of HRVi, SDNN, and RMSSD (P < 0.0001). The consistency of HRVi was similar to that of SDNN (4.8% +/- 2.1% vs 5.7% +/- 4.8%, P = 0.4), and the consistency of RMSSD (26.6% +/- 13.3%) was significantly lower than that of the other measurements (P < 0.00001). In conclusion, the measurements of mNN by different analytical systems are the most consistent among the parameters studied. The global 24-hour measurements of HRV (SDNN and HRVi) are highly reproducible, whereas the measurement of short-term HRV components (RMSSD) is significantly less reproducible.     

Arrhythmia Risk Prediction in Idiopathic Dilated Cardiomyopathy Based on Heart Rate Variability and Baroreflex Sensitivity

This study examined the relation between heart rate variability (HRV) and baroreflex sensitivity (BRS) and subsequent major arrhythmic events (MAE), defined as sustained VT, VF or sudden death, in 263 patients with idiopathic dilated cardiomyopathy (IDC) in sinus rhythm. The predefined measure of HRV was the standard deviation of all normal-to-normal RR intervals (SDNN) on baseline 24-hour ambulatory ECG. BRS was determined by the phenylephrine method. Over 52 ± 21 months of follow-up, MAE occurred in 38 patients (14%). SDNN at baseline 24-hour ambulatory ECG (106 ± 46 vs 109 ± 45, ns) and BRS (7.9 ± 5.5 vs 7.7 ± 5.3 ms/mmHg, ns) were both similar in patients with versus without MAE during follow-up. In contrast, left ventricular ejection fraction was significantly lower in patients with versus without MAE (24%± 7% vs 31%± 10%, P < 0.019. Conclusions: Neither HRV nor BRS predicted MAE in patients with IDC.     

Changes in Heart Rate, Heart Rate Variability, and Heart Rate Turbulence during Evolving Reperfused Myocardial Infarction

Depressed cardiac parasympathetic activity is associated with electrical instability and adverse outcomes after myocardial infarction (MI). Heart rate turbulence (HRT), reflecting reflex vagal activity, and heart rate variability (HRV), reflecting tonic autonomic variations are both reduced in the subacute phase of MI. However, the evolution of these components of cardiac autonomic control between subacute and chronic phase of MI has not been defined. We prospectively studied 100 consecutive patients with a recent first MI with ST-segment elevation, who underwent successful direct percutaneous coronary interventions. Beta-adrenergic blockers and angiotensin-converting enzyme (ACE) inhibitors were administered according to the state-of-the-art medical practice guidelines. HRT and HRV were measured from 24-hour ambulatory electrocardiographic recordings 10 days and 12 months after the index MI. There was no significant difference in mean RR interval between the subacute and chronic phase of MI (875 ± 145 versus 859 ± 122 ms). Indices of HRV increased significantly during the observation period (SDNN: from 88.8 ± 26.8 to 116.0 ± 35.7 ms, P < 0.001; SDNNi: from 37.9 ± 15.9 to 46.0 ± 16.3 ms, P < 0.001; SDANN: from 79.6 ± 34.7 to 105.6 ± 35.4 ms, P < 0.001). In contrast, there were no significant changes in indices of HRT (turbulence onset: from −0.008 ± 0.022 to −0.012 ± 0.025%; turbulence slope: from 7.78 ± 5.9 to 8.06 ± 6.8 ms/beat). In contrast to reflex autonomic activity, there was a significant recovery of tonic autonomic activity within 12 months after MI. These different patterns of recovery of reflex versus tonic cardiac autonomic control after MI need to be considered when risk stratifying post-MI patients.     

Heart Rate Variability Used as an Arrhythmia Risk Stratifier After Myocardial Infarction

Heart rate variability (HRV) is considered to represent a noninvasive tool to assess cardiac autonomic tone at the level of the sinus node. It has been shown to have predictive power for risk assessment in patients surviving acute myocardial infarction. For this purpose, HRV should be assessed from 24-hour Holter recordings obtained 7–10 days following the infarction. Although there is some recovery of HRV during the first 3 months after infarction, HRV remains reduced in postinfarction patients compared to values obtained in healthy individuals. Compared to assessment of left ventricular function as a risk marker, HRV is superior with respect to prediction of arrhythmic events and sudden death whereas both parameters yield comparative power for prediction of total cardiac mortality. Since the predictive power of HRV analysis alone is relatively low, the combined use of HRV measurements together with traditional risk markers (such as ventricular ectopic beats, signal-averaged ECG, or left ventricular function) results in improved risk prediction with positive predictive accuracy in the range of 30%–50%.     

Heart rate variability in arrhythmogenic right ventricular cardiomyopathy correlation with clinical and prognostic features

The identification of subjects with arrhythmogenic right ventricular cardiomyopathy (ARVC) at higher risk for sudden death is an unresolved issue. An influence of the autonomic activity on the genesis of ventricular arrhythmias was postulated. Heart rate variability (HRV) analysis provides a useful method to measure autonomic activity, and is a predictor of increased risk of death after myocardial infarction. For these reasons, the aim of the study was to evaluate HRV and its correlations with ventricular arrhythmias, heart function, and prognostic outcome in patients with ARVC. The study included 46 patients with ARVC who were not taking antiarrhythmic medications. The diagnosis was made by ECG, echocardiography, angiography, and endomyocardial biopsy. Exercise stress test and Holter monitoring were obtained in all patients. Time-domain analysis of HRV was expressed as the standard deviation of all normal to normal NN intervals (SDNN) detected during 24-hour Holter monitoring. Thirty healthy subjects represented a control group for HRV analysis. The mean follow-up was 10.8 +/- 1.86 years. SDNN was reduced in patients with ARVC in comparison with the control group (151 +/- 36 vs 176 +/- 34, P = 0.00042). Moreover, there was a significant correlation of this index with the age of the patients (r = - 0.59, P < 0.001), with the left (r = 0.44, P = 0.002) and right (r = 0.47, P = 0.001) ventricle ejection fraction, with the right ventricular end diastolic volume (r = - 0.62, P < 0.001), and with the ventricular arrhythmias, detected during the same Holter record used for HRV analysis (patients with isolated ventricular ectopic beats < 1,000/24 hours, 184 +/- 34; patients with isolated ventricular ectopic beats > 1,000/24 hours and/or couplets, 156 +/- 25; patients with repetitive ventricular ectopic beats (> or = 3) and/or ventricular tachycardia, 129 +/- 25; P < 0.001). During follow-up two patients showed a transient but significant reduction of SDNN and a concomitant increase of the arrhythmic events. In eight patients an episode of sustained ventricular tachycardia occurred, but the mean SDNN of this subgroup did not differ from the mean value of the remaining patients (152 +/- 15 vs 150 +/- 39; P = NS). Only one subject died after heart transplantation during follow-up (case censored). Time-domain analysis of HRV seems to be a useful method to assess the autonomic influences in ARVC. A reduction of vagal influences correlates with the extent of the disease. The significant correlation between SDNN and ventricular arrhythmias confirmed the influences of autonomic activity in the modulation of the electrical instability in ARVC patients. However, SDNN was not predictive of spontaneous episodes of sustained ventricular tachycardia.     

Changes in Heart Rate Variability with Age

Depressed heart rate variability (HRV) after a myocardial infarction is associated with increased mortality. This is thought to be due to reduced parasympathetic activity and heightened sympathetic activity. Aging is associated with depressed HRV, but little is known of the affect of aging on parasympathetic activity. This study examined 56 healthy subjects (age range 40–102 years; 39 women). None had a history of heart disease or were on medication that would affect cardiac function. All had normal resting ECGs, normal heart size on chest X ray, and normal electrolytes. In all subjects, 24-hour Holter recordings were performed and used to measure HRV. In particular, the study examined the affect of age on HRV triangular index, which gives an estimate of overall HRV, and on RMSSD (square root of the mean squared differences of successive normal-to-normal RR intervals), which gives an estimate of short-term components of HRV and is thought to reflect the overall extent of vagal modulations of heart rates. Both these parameters were compared in patients younger and older than 70 years. Each recording lasted at least 17 hours; the majority of recordings were longer than 20 hours. There was a significant decrease in HRV triangular index with age (r =?0.4, P < 0.05) and no significant change in RMSSD with age(r =?0.08, P = NS). There was a significant difference in HRV index in those > 70 years compared with those < 70 years (38.0 ± 9.3 vs 31.0 ± 11, respectively, P <0.02). There was no significant difference in RMSSD between the two age groups (26.7 ± 8.2 ms vs 28.4 ± 11.3 ms, respectively, P = NS). Thus, the study concludes that aging reduces the global measure of HRV and may reflect reduced responsiveness of autonomic activity to external environmental stimuli with age. However, the time-domain short-term components of HRV are not affected by age and, therefore, the fast and presumably vagal modulations of heart rate appear to be maintained.     

Exploratory Study of Heart Rate Variability and Sleep among Emergency Medical Services Shift Workers

Objectives: To characterize the continuity and duration of sleep, and to measure nocturnal cardiac autonomic balance via heart rate variability (HRV) in a group of emergency medical technicians (EMTs) on and off duty. Methods: Fourteen EMTs completed an online, daily sleep log that recorded total sleep duration, bedtime, rise time, and the number of alarms that caused awakening. HRV was captured using a physiological status monitor (PSM) affixed to a chest strap during sleep. Results: For the 7-day trial, each of the 14 EMTs logged three work days (WDs) and four non-work days (NWDs). They reported sleeping significantly fewer hours per night on WDs (6.4 ± 2.1) than on NWDs (7.9 ± 0.5; P < 0.05), and experienced more sleep disruptions on WDs (4.4 ± 2.8) than on NWDs (1.3 ± 2.2; P < 0.001) as measured by the number of alarms. Global and vagal indices of HRV during sleep were significantly reduced during WDs (Standard Deviation of Normal R-R Intervals (SDNN) = 43.4 ± 2.0 ms and High Frequency (HF) = 24.3 ± 1.2 ms²) when compared to NWDs (SDNN = 61.1 ± 1.0 ms and HF = 42.7 ± 1.5 ms²; P < 0.001). Conclusion: EMTs who worked 24-hour shifts had shorter, more fragmented sleep associated with greater cumulative exposure to increased sympathetic and decreased parasympathetic activity as measured via sleep HRV. These changes in cardiac autonomic tone constitute one plausible pathway through which sleep deprivation may increase risk for cardiovascular disease.     

Heart rate variability is related to disease activity and smoking in rheumatoid arthritis patients

We investigated the heart rate variability (HRV) parameters in patients with rheumatoid arthritis (RA) and assessed their relationship with disease characteristics. Twenty-three female patients with RA [age 48+/-7 (mean+/-SD) years] free of cardiovascular diseases and 23 age- and gender-matched healthy controls were evaluated. After careful clinical examination, the following parameters were obtained after 24-h Holter recordings: average of all normal-to normal (NN) intervals over the entire 24-h ECG recording (meanNN, ms); the standard deviation for the time between NN complexes (SDNN, ms); the standard deviation of the average NN intervals for each 5-min period (SDANN, ms) and the square root of the mean-squared differences of successive NN intervals (rMSSD, ms). We also assessed quantitative parameters of the Poincaré plot: the standard deviation of the points perpendicular to the line-of-identity (SD1, ms); the standard deviation along the line-of-identity (SD2, ms) and their ratio (SD12). HRV parameters excluding SD2 were significantly lower in patients with RA, than in control group (p<0.05). Significant correlations of SDNN and SDANN with swollen joints count, Ritchie articular index, disease activity score (DAS) and disease duration were found. SDNN also correlated with leucocyte count and smoking. SD1 significantly correlated only with disease duration. Relationships between SDNN and smoking, swollen joints count and DAS were confirmed using multivariate analysis. Our data indicate that in patients with RA reduced HRV is independently associated with high disease activity and smoking. HRV assessment may be useful as a part of cardiovascular risk stratification in RA patients.     

80例健康人心率变异分析

心率变异分析（ＨＲＶ）为近年来发展起来的一项定量评价体内自主神经活动的新方法，并被认为是预测心性猝死特别是心梗后猝死的敏感和独立的指标。本研究采用英国Ｏｘｆｏｒｄ公司ＭｅｄｉｌｏｇＯｐｔｉｍａ２４－ｈＨｏｌｔｅｒ系统，测算了８０名１６～６５岁健康人的６项心率变异指标。结果为：ＭｅａｎＮＮ８１３．３３±４６．３９，ＳＤＮＮ１３２．６８±２２．６４．ＳＤ５２．９８±１２．０３，ＳＤＡＮＮ１１９．５１±２１．５５，ｒＭＳＳＤ２８．８２±９．９４，ｐＮＮ５０９．７０±７．４４。本文观察到随年龄增长而ＨＲＶ指标略有降低的趋势，但除ｐＮＮ５０外，均无统计学差异，ＭｅａｎＮＮ、ＳＤＮＮ、ＳＤＡＮＮ、ｐＮＮ５０４项指标值夜间均显著高于白天（Ｐ＜０．０５～０．００１）。并对ＨＲＶ的正常值范围、意义及其影响因素进行了讨论。认为ｐＮＮ５０对测定副交感神经张力较敏感。     

原发性高血压伴左心室肥厚者的心率变异性

目的　分析原发性高血压 (EH)伴左心室肥厚者的心率变异性 (HRV)变化及与左心室肥厚程度的关系。方法　对 16 8例EH患者和 6 2例正常人 2 4h动态心电图和心脏超声资料进行对比分析。结果　EH无左心室肥厚组仅相邻正常R R间期差值 >5 0ms的百分比 (PNN5 0 )显著低于对照组 (P <0 0 1) ,而EH左心室肥厚组的各项HRV指标均显著低于对照组 ,EH左心室肥厚组的 2 4h正常R R间期的标准差(SDNN)、5min平均正常R R间期的标准差 (SDANNindex)和 5min正常R R间期标准差的均值 (SDNNin dex)又显著低于EH无左心室肥厚组 (P <0 0 1,P <0 0 1,P <0 0 5 )。结论　EH左心室肥厚患者的HRV降低 ,HRV与左室肥厚的程度呈负相关。     

Heart Rate Variability During Head-up Tilt Testing in Patients with Suspected Neurally Mediated Syncope

The relation between heart rate variability (HRV) and outcome of head-up tilt testing (HUT) in patients with neurally mediated syncope (NMS) was studied in 30 patients with presumed NMS (33 ± 13 years) and in 11 age-matched controls. After 15 minutes of baseline supine observation, patients were tilted to 60± for 45 minutes or until syncope occurred. HRV parameters included RR intervals, standard deviation of normal-to-normal RR intervals (SDNN), and root mean square successive differences (RMSSD). HRV analysis was performed during 5-minute intervals in the supine position immediately after onset of HUT and before syncope or after 30–35 minutes of tilt in patients without syncope. Syncope occurred after a mean tilt duration of 32 minutes in 14 (47%) of 30 patients with presumed NMS, whereas all controls had an uneventful HUT. In the supine position, RR intervals and RMSSD were comparable among HUT-positive patients, HUT-negative patients, and controls (RR intervals: 799 ± 92, 854 ± 137, and 818 ± 128 ms, P = NS; RMSSD: 43 ± 40, 36 ± 34, and 53 ± 42 ms, P = NS). Baseline SDNN was also comparable in HUT-positive patients versus HUT-negative patients with presumed NMS (50 ± 26 vs 52 ± 20 ms, P = NS). Within 5 minutes preceding syncope or after 30–35 minutes of tilt, RR intervals and RMSSD were shorter in HUT-positive patients compared to HUT-negative patients, or to controls (RR intervals: 606 ± 86 vs 710 ± 117 and 739 ± 123 ms, P < 0.05; RMSSD: 12 ± 5 vs 23 ± 19 and 40 ± 32 ms, P < 0.05). Thus, HRV analysis in the baseline supine position was not a predictor of HUT outcome in patients with suspected NMS. Syncope during HUT seemed to be preceded by increased sympathetic activity manifested by an increase in heart rate and by a decreased parasympathetic tone manifested by a decrease in RMSSD measured for 5 minutes before the event, in comparison with HUT-negative patients and with controls.     

Value of Heart Rate Variability to Predict Ventricular Arrhythmias in Recipients of Prophylactic Defibrillators with Idiopathic Dilated Cardiomyopathy

GRIMM, W., et al. : Value of Heart Rate Variability to Predict Ventricular Arrhythmias in Recipients of Prophylactic Defibrillators with Idiopathic Dilated Cardiomyopathy. This study investigated the relation between heart rate variability (HRV) measured as standard deviation of normal to normal RR intervals (SDNN) on baseline 24-hour ambulatory electrocardiogram (ECG) and subsequent appropriate implantable cardioverter defibrillator (ICD) interventions in 70 patients with idiopathic dilated cardiomyopathy (IDC) in whom ICDs were implanted prophylactically in the presence of a low left ventricular ejection fraction (LVEF). During   43 ± 26   months of follow-up, 26 of 70 (37%) study patients with IDC received one or more appropriate ICD interventions for sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) documented by electrograms stored in the ICD. Mean SDNN at ICD implant was   94 ± 33 ms   . No difference was found between patients with   (90 ± 25 ms)   versus without   (96 ± 37 ms)   appropriate ICD interventions for VT or VF during follow-up. Multivariate Cox regression analysis of baseline clinical characteristics including age, gender, LVEF, NYHA functional class, nonsustained VT on Holter, history of syncope, left bundle branch block, baseline medication and HRV revealed LVEF as the only significant predictor of arrhythmia. These findings do not support the use of HRV measured as SDNN on 24-hour ambulatory ECG to select patients with IDC for prophylactic ICD therapy. (PACE 2003; 26[Pt. II]:411–415)     

运动、昼夜节律和呼吸对心率变异性的影响(英文)

目的探索运动、昼夜节律和呼吸对心率变异性的影响。方法2000-01/2000-02从第三军医大学西南医院门诊收集34名自愿受试者,于清晨5h和下午5h、运动前后分别记录心动周期信号,并测量和分析。用相继各心动周期的标准差(SDNN)作为心率变异性的一个指标。结果10名受试者清晨5h和下午5h心率变异性指标SDNN的均值分别为30ms和29ms,而清晨5h和下午5h两组心动周期数据汇成一组时的SDNN增大至262ms;34名受试者运动前SDNN的均值为18ms,运动后的SDNN的均值为10ms,受试者运动前后心率变异性的差异非常显著(t=6.049,P<0.01);呼吸周期I内的心动周期最大差值与呼吸周期J内的心动周期最大差值之间的差异不显著(t=0.024,P>0.05)。结论长时程(24h)心率变异性指标SDNN的正常值(141±39)ms的基础之一是心动周期的昼夜差;运动是影响心率变异性的重要因素;呼吸对心率变异性有一定的影响,但其大小次于心动周期的昼夜差对心率变异性的影响。     

Recombinant interferon alpha treatment decreases heart rate variability indices and impairs exercise tolerance in patients with chronic hepatitis

Complications of interferon (IFN) therapy include cardiac arrhythmias, impaired cardiac function and myocardial ischemia. Decreased heart rate variability (HRV) indices, impaired exercise tolerance and decreased left ventricular (LV) function are related to unfavorable outcome of heart disease. To investigate the effect of IFN therapy on HRV, exercise tolerance and cardiac function, 24-h ambulatory electrocardiographic monitoring (AECG), two-dimensional echocardiography, and exercise treadmill testing (ETT) was performed in 9 patients (age 56 ± 9 years-old) with chronic hepatitis and without underlying heart disease before and after treatment with IFN (recombinant alpha 2b; 10 × 10⁶ U/day for 4 weeks). HRV parameters consisted of standard deviation of RR interval (sdNN, ms), SDANN (ms), S.D. index (ms), rMSSD (ms), pNN50 (%) and frequency analysis of heart rate spectrum resulted in low (ms, 0.04–0.15 Hz), high (ms, 0.15–0.40 Hz) and total (ms, 0.01–1.00 Hz) frequency components. Ischemia was not detected by AECG or ETT, and LV function was normal after INF treatment in all patients. However, INF treatment resulted in a decrease in exercise tolerance time (449 ± 94 s vs. 329 ± 67 s, P < 0.05) and a decrease in several HRV parameters (S.D. index, 42 ± 5 ms vs. 37 ± 9 ms; rMSSD, 22 ± 5 ms vs. 19 ± 4 ms; pNN50, 4 ± 3% vs. 2 ± 1%; P < 0.05). Further, patients treated with INF tended to have a lower sdNN and total frequency spectra, although this difference did not reach the level of statistical significance. These data suggest that the arrhythmogenic effect of INF may be mediated by decreases in HRV and impairment of exercise tolerance even in patients without overt heart diseases. Further, INF therapy may be contraindicated in patients with predisposing severe cardiac disorders, including arrhythmias, ischemia and decreased LV function.     

Autonomic nervous system balance, variability and arrhythmia in survivors of myocardial infarction

AIM: To investigate relations between heart rhythm variability (HRV), vegetative balance and electric myocardial activity in myocardial infarction (MI) survivors. MATERIAL AND METHODS: HRV was studied by short 5-min parts of ECG and data of ECG Holter monitoring were analysed for 98 patients who had macrofocal MI 1.5 months to 5 years before. RESULTS: Manifestations of electric heart instability were polymorphic. 69.4% examinees had hyperactivity of the parasympathetic nervous system (PSNS). The influence of the sympathetic nervous system (SNS) increased with growing severity of arrhythmia. Supraventricular arrhythmia occurred more frequently in high PSNS activity, while ventricular arrhythmia occurred more often in SNS prevalence combined with low HRV. CONCLUSION: HRV analysis for MI survivors, especially in combination with Holter ECG monitoring, gives an objective assessment of various manifestations of cardiac dysfunction and therefore enables timely adequate therapy.     

急性重症脑卒中早期心率变异的研究

目的 :研究急性重症脑卒中早期心率变异 (HRV)的变化及其临床意义 ,建立 HRV对脑功能损伤的评价标准。方法 :大脑半球部位脑卒中患者 3 5例 ,根据格拉斯哥昏迷评分 (GCS)分为急性重症组 (GCS≤ 8分17例 )和非重症组 (GCS>8分 18例 )。所有患者发病 5 d内进行 Holter连续监测。结果 :1重症组与非重症组相比 HRV明显降低 ,以反映植物神经总活性和副交感神经活性的指标突出。 2动态监测发现正常 RR间期标准差 (SDNN)≤ 60 ms、总频谱 (TF)≤ 15 0 0 ms2 / Hz、高频谱 (HF)≤ 60 0 ms2 / Hz、低频谱 (L F)≤ 10 0 0 ms2 / Hz是预测预后的界限值 ;上述指标低于界限值提示病情恶化 ,预后不良 ;高于界限值则预示病情向好的方向发展 ,预后良好 ,其动态变化早于传统的 GCS。 3多因素 L ogistic回归分析显示仅 TF、HF和 GCS3个变量的 P值具有显著性差异 ,预后良好的预测准确率为 82 .14 % ,预后不良的预测准确率为 88.89%。结论 :重症脑卒中患者反映植物神经总活性和副交感神经活性的 HRV指标明显降低 ,HRV是预测急性重症脑卒中预后的一个独立、敏感、定量的指标。动态监测 HRV可判断脑功能损伤程度 ,了解病情演变趋势 ,优于传统的临床指标     

心率变异性和NT-proBNP对慢性心力衰竭患者病情评估及预后的临床应用价值

目的探讨心率变异性（HRV）和血浆N末端脑钠肽前体（NT-proBNP）水平对慢性心力衰竭（CHF）患者病情评估及预后的临床应用价值。 方法选取2016年9月至2017年12月在六安市第二人民医院住院的177例CHF患者为研究对象。根据患者心功能分级,将其分为心功能Ⅱ~Ⅲ级组和心功能Ⅳ级组：心功能Ⅱ~Ⅲ级组包括心功能Ⅱ级患者28例,心功能Ⅲ级患者63例,共91例;心功能Ⅳ级组均为心功能Ⅳ级患者,共86例。对两组患者性别、伴发疾病情况的比较采用χ²检验;对两组患者年龄、血浆NT-proBNP水平,以及HRV时域指标SDNN、RMSSD、PNN50和三角指数的比较采用独立样本t检验。 结果心功能Ⅱ~Ⅲ级组CHF患者血浆NT-proBNP水平显著低于心功能Ⅳ级组,差异有统计学意义［（1545.2±147.5）ng/L vs（4012.6±983.2）ng/L,t=49.510,P<0.001］;心功能Ⅱ~Ⅲ级组CHF患者HRV时域指标SDNN、RMSSD、PNN50和三角指数均显著高于心功能Ⅳ级组患者,差异有统计学意义［（95.56±15.16）ms vs（68.74±12.58）ms,t=15.294,P<0.001;（19.04±7.62）ms vs（15.23±5.29）ms,t=9.275,P=0.001;（5.59±2.23）% vs（4.48±2.65）%,t=5.601,P=0.002;（13.22±6.82）vs（10.69±4.53）,t=2.748,P=0.011］。心功能Ⅱ~Ⅲ级组房性心律失常、心血管事件、房性心律失常伴心血管事件的发生率均明显低于心功能Ⅳ级组,差异有统计学意义［27例（29.7%）vs 40例（46.5%）,χ²=15.130,P<0.001;9例（9.9%）vs 14例（16.3%）,χ²=11.577,P<0.001;4例（4.4%）vs 8例（9.3%）,χ²=10.836,P=0.001］。 结论血NT-proBNP水平和HRV各项时域指标均对CHF患者诊断、治疗及预后具有重要临床应用价值。