Role of Heart Rate Variability in the Early Diagnosis of Diabetic Autonomic Neuropathy in Children

Background: Diabetic autonomic neuropathy (DAN) is a major complication of diabetes. DAN has been shown to be closely related to glycemic control. To contribute significantly to the morbidity and mortality of the disease, and to be indicative of an increased risk of cardiovascular events. Tests asssing the function of the autonomic nervous system, such as the response of heart rate and blood pressure to maneuvers stimulating the autonomic nervous system, including deep breathing. Valsalva maneuver and standing, allowed to detect signs of DAN in adolescents; however, the sensitivity of such tests in revealing an early impairment of the autonomic nervous system proved low. Several studies found heart rate variability (HRV) to be useful in assessing the dysfunction of the autonomic nervous system in diabetic children and adolescents, but only few HRV parameters were evaluated in most of them. Objective: To study cardiac autonomic nervous system in diabetic children, and to investigate whether the duration of diabetes and the degree of metabolic control are determinants for the development of DAN in children. Patients and Methods: We analyzed HRV in 50 asymptomatic patients with insulin-dependent diabetes mellitus (IDDM) and 30 healthy children matched for age and sex. Results: Patiens with a history of diabetes > 8 years showed significant alterations of the autonomic nervous systemm (significant reduction of r-MSSD, pNN50, HF and increase in LF/HF). Conversely, only a reduction in pNN50 was found in patients with a disease duration < 8 years. Furthermore, we also observed significant HRV abnormalities in patients with an impaired metabolic control of diabetes. Compared to controls, patients with glycosylated hemoglobin blood levels (HbA_1C) > 8% showed a significant reduction of r-MSSD, pHH50 and total power spectrum, whereas no HRV abnormalities were detected in patients with an HbA_1C < 8%. Conclusions: HRV analysis can detect early subclinical alterations of the autonomic nervous system in asymptomatic patients with IDDM, which seem to consist mainly in a parasympathetic impairment. Autonomic dysfunction is associated both with the duration and an inadequate metabolic control of the disease. Hintergrund: Die diabetische Polyneuropathie (DAN) ist eine Hauptkomplikation des Diabetes mellitus. Die DAN zeigt eine enge Beziehung zur Kontrolle der Blutzuckerwerte und trägt signifikant zur Morbidität und Letalität der Erkrankung bei und weist auf eine erhöhte kardiovaskuläre Ereignisrate hin. Die DAN kann bei Erwachsenen mittels spezieller Teste geprüft werden, die die Herzfrequenzänderung und das Blutdruckverhalten untersuchen, wenn Provokationsverfahren zum Beispiel mit Valsalva-Manöver, tiefer Atmung und Stehversuch durchgeführt werden. Die Teste weisen aber eine geringe Sensitivität auf. Die Herzfrequenzvaviabilität (HRV) selbst ist aber ein gutes Verfahren, um eine autonome Dysregulation aufzudecken. Ziel: Prüfung des autonomen Nervensystems bei Kindern mit Diabetes mellitus in Abhängigkeit von der Dauer und Schwere der gestörten Glucosestoffwechselsituation. Patienten und Methoden: Bei 50 Patienten mit insulinpfichtigem Diabetes mellitus und 30 gesunden Kindern wurde die HRV geprüft. Ergebnisse: Patienten mit einer Diabetesdauer über 8 Jahre zeigten eine signifikante Störung des autonomen Nervensystems mit Reduktion der HRV. War die Dauer des Diabetes weniger als 8 Jahre, war nur der Parameter pNN 50 erniedrigt. Eine gestörte HRV wurde nur bei Patienten mit geströter metabolischer Situation gefunden. Bei Patienten mit einem HbA_1C Wert > 8% fanden sich erniedrigte Werte für r-MSSD, pNN50 und das Gesamtpowerspektrum im Vergleich zu Kontrollpersonen. Patienten mit HbA_1C-Werten unter 8% blieben demgegenüber unauffällig. Schlussfolgerung: Die HRV-Analyse bei insulinplfichtigen Kindern mit Diabetes mellitus kann genutzt werden, um im subklinischen Bereich eine Störung der autonomen Funktion des Nervensystems zu überprüfen. Im Wesentlichen liegt eine Parasymathikusstörung vor. Die autonome Dysregulation ist korreliert zur Dauer und zum metabolischen Status der Kinder.     

比索洛尔对糖尿病自主神经病变患者心率变异性的影响

目的：通过比较糖尿病自主神经病变者服用比索洛尔（康可）前、后心率变异（HRV）的变化，以了解比索洛尔对HRV的影响。方法？用动态心电图测定50例糖尿病自主神经病变的病人在比索洛尔治疗前、后的HRV时域各项指标，并与对照组50例进行比较。结果：与对照组比较，比索洛尔组的心率变异时域指标SDNN、rMSSD、pNN50均明显下降（P〈0．01）。治疗组比索洛尔治疗后SDNN、rMSSD、pNN50均较用药前显著升高（P〈0．01）。结论：糖尿病合并自主神经病变者HRV降低，比索洛尔能提高心率变异性，改善预后。     

肠易激综合征患者心血管自主神经功能变化与心率变异性的关系

目的 :探讨肠易激综合征 (1BS)患者心血管自主神经功能变化与心率变异性 (HRV)的关系。方法 :对IBS患者 50例进行标准心血管自主神经功能测试 ,将其结果分成阳性组 (DNA+ )及阴性组 (DNA- ) ,健康人 30名为对照组。 2 4h动态心电图进行HRV分析。结果 :IBS患者自主神经功能异常的发生率为 58% ,主要表现为迷走神经功能异常 ;HRV时域分析中DNA+ 组SDNN、SDANN、SDNNindex明显减少 ;DNA+ 及DNA- 组中反映副交感神经张力的RMSSD、PNN50 、HF等指标明显增高 ,LF/HF比值明显减低 ,与对照组比较有显著性差异 (P <0 .0 5)。结论 :IBS患者存在副交感神经张力增加。HRV分析是发现IBS患者自主神经功能异常的较好方法     

Incipient cardiovascular autonomic imbalance revealed by wavelet analysis of heart rate variability in Type 2 diabetic patients.

AIM: Incipient cardiovascular autonomic imbalance is not readily diagnosed by conventional methods. Spectral analysis of heart rate variability (HRV) by wavelet transform (WT) was used to measure cardiovascular autonomic function in patients with Type 2 diabetes. METHODS: Thirty-two diabetic patients without (D), 26 with cardiovascular autonomic neuropathy (DAN) and 72 control subjects (C) participated. A 30-min HRV time series was analysed by wavelet transformation and four characteristic frequency intervals were defined: I (0.0095-0.021 Hz), II (0.021-0.052 Hz), III (0.052-0.145 Hz) and IV (0.145-0.6 Hz). RESULTS: When compared with C, in both D and DAN the normalized power and amplitude of interval II were increased and of interval IV decreased, resulting in a significantly higher II/IV ratio. Furthermore, in DAN the normalized power and amplitude of interval I were increased and of interval III decreased when compared with the D and C groups. The diabetic patients were divided in two equal subgroups according to HbA(1c) < 8.0% and >or= 8.0%. In the subgroup with HbA(1c) >or= 8.0%, normalized power in interval II was significantly higher and in interval IV significantly lower than in the subgroup with HbA(1c) < 8.0%. In D, but not in DAN patients prescribed ACE inhibitors, the absolute amplitude and power of oscillations were significantly higher than in patients not taking ACE inhibitor therapy. CONCLUSIONS: Patients with diabetes have increased sympathetic and decreased parasympathetic cardiac activity regardless of the presence of autonomic neuropathy. Glycaemic control and treatment with ACE inhibitors may favourably influence HRV in diabetic patients without autonomic neuropathy.     

Compromise of the cardiac autonomic nervous system in patients with Fontan-type circulation: preliminary data

BACKGROUND: Rhythm disturbances are frequent after Fontan operations. Arrhythmias related to reduced heart rate variability (HRV) have been described in various cardiovascular diseases. METHODS: We attempted to investigate HRV in 12 patients who underwent Fontan operation (age 11.4 +/- 3 years). Results were compared to a control group of 13 children matched for age, sex and heart rate (10.4 +/- 3 years). All patients underwent 24-hour Holter monitoring. The following time domain indexes were calculated: mean duration of RR intervals, standard deviation of all RR intervals (SD), square root of the mean squared differences of successive RR intervals (r-MSSD), percentage of differences between adjacent RR intervals > 50 msec (pNN50). The following frequency domain indexes were calculated: total power (TP), low frequency (LF), high frequency (HF), LF/HF ratio. RESULTS: The following indexes were significantly reduced in Fontan patients: SD (p < 0.0001), r-MSSD (p < 0.0001), pNN50 (p = 0.0002), TP (p < 0.0001), LF (p < 0.0001), HF (p = 0.0001). LF/HF increased significantly (p = 0.04). No differences were detected according to the type of operation (cavopulmonary connection vs atriopulmonary connection) or clinical status. CONCLUSIONS: Patients with Fontan circulation had a significantly reduced HRV and particularly abnormal sympatho-vagal balance. Surgery on the caval veins and the atria alters the intracardiac ganglia that are abundant at the cavo-atrial junction and in the myocardium of the right atrium. Abnormalities of HRV in Fontan patients may act as a co-factor in the initiation of arrhythmia in these patients.     

糖尿病患者心率减速力与心率变异性分析

目的探讨心率减速力（decelerationcapacityofhearrate,DC）与心率变异性（heartratevariability,HRV）在评价糖尿病患者自主神经功能方面的应用。方法对73例2型糖尿病患者和65名正常人群对照组进行24h动态心电图检查,离线计算DC、HRV时域指标并进行比较和相关分析。结果2型糖尿病患者的DC及HRV各时域指标均比对照组降低,差异均有统计学意义（P〈0．05）。相关分析结果显示,2型糖尿病组DC与HRV中的总标准差（SDNN）呈正相关（r=O．597,P〈O．01）,与差值均方根（RMSSD）呈正相关（r=O．569,P〈0．01）,与pNN50呈正相关（r=0．501．P〈0．05）。结论DC和HRV各时域指标有较好的相关性,可作为2型糖尿病患者自主神经功能检测的指标。     

Sex steroids and heart rate variability in men with coronary artery disease after myocardial infarction

The role of sex steroids in coronary artery disease (CAD) has been studied for years. In patients after myocardial infarction autonomic nervous system dysfunction has been described. Heart rate variability (HRV) analysis is one of the method of autonomic nervous system evaluation. The aim of the study was to evaluate correlations between sex steroids and HRV in 88 men (aged 36-73, av. 53 yrs), with the history of MI, with angiographically documented CAD. In all the patients 24-hour Holter monitoring was performed to assess HRV time domain parameters: SDNN, SDNNI, SDANN, rMSSD, pNN50. Levels of testosterone and estradiol were measured in two subsequent blood samples, taken with 30 min interval. Free testosterone index as well as estradiol/testosterone ratio were assessed. For statistics r-Spearman test was used. Positive correlations were found between testosterone and SDNN (r = 0.38, p = 0.03), testosterone and rMSSD (r = 0.51, p = 0.002) and between testosterone and pNN50 (r = 0.45, p = 0.007). Since rMSSD and pNN50 are parameters describing parasympathetic activity, our results suggest that in CAD men with the history of myocardial infarction, testosterone may influences the function of autonomic nervous system promoting parasympathetic dominance. It can be favorable for the circulatory system function.     

Heart rate variability in healthy children and adolescents is partially related to age and gender.

We evaluated 24-h time-domain heart rate variability (HRV) in 103 (46 females) healthy children and adolescents. Subjects were divided into four male and four female groups (ages 1-5, 6-10, 11-15, 16-20 years) and 24-h ambulatory Holter monitoring was performed. HRV was assessed by SDNN, SDNN index (SDNN-i), SDANN, rMSSD, pNN50. Males showed SDNN and SDANN values significantly higher than females while for SDNN-i, rMSSD, pNN50 there were no significant differences between sexes. With increasing age, there is a progressive and significant decrease of HR and increase of SDANN. On the other hand, SDNN, SDNNi, pNN50 and rMSSD increased significantly only between the first two age-groups. rMSSD and pNN50 were significantly related to body mass index. Thus, SDNN and SDANN, overall HRV measures, increased with age and were gender-related. HRV indices of parasympathetic function (rMSSD, pNN50) and SDNN-i increased up to 10 years of age and were gender-unrelated. These data demonstrate that in healthy children and adolescents there is a progressive modification of HRV that may reflect a progressive evolution of the autonomic nervous system, with different pattern measure-dependent. This paper enables us to compare, in future works, HRV in pediatric subjects in different groups according to the different HRV measures under examination.     

十二指肠溃疡患者心血管自主神经功能变化与心率变异性的关系

目的：探讨十二指肠溃疡（DU）患者心血管自主神经功能变化与心率变异性（HRV）的关系。方法：将80例DU患者进行标准心血管自主神经功能试验（DAN），据此结果分成阳性组（DAN^ )及阴性组（DAN^-)。设80名健康人为对照组。动态记录24h心电图并进行HRV分析。结果：DU患者心血管自主神经功能异常的发生率为52．5％，主要表现为迷走神经功能异常；DAN% 组HRV分析中时域指标SDNN、SDNNindex、SDANN均减小（P＜0．05），且反映副交感神经张力改变的RMSSD、PNN50、HF等指标在DAN^ 组及DAN^-组中均明显增高，LF／HF比值明显减低，与对照组比较，差异有显著性（P＜0．05）。结论：DU患者存在副交感神经张力增加，副交感神经张力改变在DU发病中起着重要的作用。HRV分析是临床早期发现DU患者心血管自主神经功能异常的较好方法。     

Diagnosis of diabetic autonomic neuropathy in young patients with diabetes mellitus type 1

Autonomic neuropathy, particularly cardiovascular autonomic neuropathy (CAN) is one of the complications of the diabetes mellitus both types. It leads to life comfort's declination but may also be the direct cause of death in diabetes mellitus patients. It seems that degree of metabolic control and duration of the disease is connected with prevalence and severity of CAN. The aim of our study was to assess cardiac autonomic function in young subjects suffered from insulin-dependent diabetes mellitus (IDDM) with relatively short duration time of the disease. We subdivided 25 (m-12, f-13) IDDM patients aged from 18 to 30 years: mean--26 +/- 38 years, with duration time of the disease up to 10 years, normotensive and without nephropathy and retinopathy. We created 25 healthy volunteers control group with similar age and sex. In all selected subjects full Ewing's battery tests were performed as well as the spectral analysis of power heart rate variability (HRV) was assessed with Finapress device (Ohmeda 2300) and automatically computed with special software. HRV in total spectrum power TP from 0.001-0.5 Hz, high frequency (HF) band from 0.15-0.3 Hz, low frequency (LF) band from 0.03-0.15 Hz and LF/HF ratio were examined both in supine and tilt. All assessed spectral values were significantly lower in IDDM patients then these in controls whereas LF/HF were respectively higher. Valsalva tests and deep breathing HR response tests were significantly differed among groups but within normal limits. We concluded that when spectral analyse was performed, in young IDDM patients with short duration time of the disease, impairment of cardiac autonomic function was observed.     

Patients Operated for Tetralogy of Fallot and with Non-Sustained Ventricular Tachycardia Have Reduced Heart Rate Variability

BACKGROUND: To study heart rate variability (HRV) in patients operated for tetralogy of Fallot (ToF) and to identify any correlation between HRV and ventricular tachycardia (VT). PATIENTS AND METHODS: We studied HRV in 23 consecutive patients operated for ToF (mean age 14 +/- 6.6 years; mean follow-up 10.6 +/- 5.2 years). Seven patients had non-sustained VT on Holter monitoring. Two control groups were included: 18 healthy subjects and 15 patients operated for other congenital heart disease. There were no differences in age, age at surgery (in the operated groups), follow-up, and mean heart rate between the three groups. Four time and four frequency domain indices were calculated: mean duration of RR intervals, standard deviation of all RR intervals (SD), square root of the mean squared differences of successive RR intervals (r-MSSD), percent of differences between adjacent RR intervals (pNN50), total power (TP), low frequency (LF), high frequency (HF), and LF/HF ratio. RESULTS: HRV indices were identical in the two control groups but were significantly reduced in patients with ToF. Within the patients who had been operated on for ToF, HRV indices were significantly lower in the seven with non-sustained VT than in those without arrhythmias: SD (95 +/- 15 vs. 135 +/- 54 ms; p = 0.01), r-MSSD (26 +/- 9 vs. 45 +/- 20 ms; p = 0.03), pNN50 (4.4 +/- 3.4 vs. 16.5 +/- 12.5%; p = 0.001) and HF (111 +/- 97 vs. 352 +/- 291 ms(2); p = 0.009). Using stepwise multivariate regression analysis, pNN50, age at surgery, degree of pulmonary regurgitation and higher right/left ventricular ratio were independent predictive variables for VT (p < 0.0001; r(2) = 0.85). CONCLUSIONS: ToF patients, particularly those with ventricular arrhythmias, have significant impairment of sympatho-vagal balance, characterized by a reduction of vagal drive.     

脑梗死患者心率变异性分析(附50例报告)

目的　研究脑梗死患者的自主神经功能状态。方法　应用时域法对 5 0例脑梗死患者进行心率变异性分析。结果　脑梗死组与正常对照组相比所有 R- R间期均值的标准差 (SDNN)明显降低 (10 2 .0 6± 2 8.5 1,137.0 6± 2 9.0 8) ms,P<0 .0 1,HRV三角指数明显降低 (2 5 .86± 9.18,37.5 7± 14 .88;P<0 .0 5 )。相邻 R- R间期之差的均方根值 (RMSSD)、爱丁堡指数 (p NN5 0 )较正常对照组低 ,但无统计学意义。脑梗死患者心率变异昼夜比较RMSSD夜间高于日间 (18.70± 7.30 ,2 6 .2 3± 8.85 ) m s,P<0 .0 5。余指标昼夜有所变化但无统计学意义。脑梗死首次发作组与非首次发作组相比 SDNN、RMSSD、p NN5 0、HRV三角指数等指标无明显差别。结论　脑梗死患者的自主神经功能以交感神经活性占优势 ,心率变异程度降低 ,且失去了正常的昼夜规律。脑梗死后自主神经功能的改变主要与本次发作有关     

Sex Steroids and Heart Rate Variability in Patients after Myocardial Infarction

Background: Although the relationship between sex steroid levels and coronary artery disease (CAD) has been the subject of many studies there are still controversies concerning the role of sex steroids in CAD. In patients with CAD, especially after a myocardial infarction, there is evidence for autonomic nervous system dysfunction. However, there is no data detailing the relationship between sex steroids and cicardian autonomic activity in patients with CAD. The aim of the study was to evaluate the association between sex steroids and heart rate variability (HRV) parameters in postinfarction patients. Methods: In 88 postinfarction men (aged 36–73, average 53 years), 24‐hour Holter monitoring was performed to assess HRV parameters: SDNN, SDNNI, SDANN, rMSSD, pNN50, and levels of the following hormones were measured: testosterone, estradiol, free testosterone index, and estradiol/testosterone ratio. Univariate and multivariate regression analyses were used to investigate the relationship between HRV parameters and levels of tested hormones. Results: Increased testosterone levels were associated with increased SDNN (r = 0.38, P = 0.03), increased rMSSD (r = 0.51, P = 0.002), and increased pNN50 (r = 0.45, P = 0.007). These associations remained significance after adjustment for age, ejection fraction, and other relevant clinical covariates. There was no significant association between estradiol and HRV parameters. Conclusion: In men with a history of myocardial infarction, higher levels of testosterone are associated with higher HRV measures of parasympathetic activity. These findings suggest that testosterone beneficially influences autonomic regulation of the heart.     

Peculiarities of regulatory mechanisms of autonomic nervous system in patients with arterial hypertension and disturbed 24-hour blood pressure profile

BACKGROUND: Insufficient nocturnal blood pressure (BP) decline is associated with elevated risk of complications of hypertensive disease. Heart rate variability (HRV) reflects activity of sympathetic and parasympathetic parts of autonomic nervous system. AIM: To elucidate special characteristics of HRV in patients with various types of 24-hour BP rhythm. Material and methods. Bifunctional 24-hour monitoring and echocardiography were carried out in 42 men with stage I-II hypertensive disease and I-II degree of arterial hypertension (mean age 21.7+/-4.5 years) and 16 practically healthy young people (mean age 24.6+/-5.2 years). RESULTS: Subjects with insufficient (<10%) and adequate nocturnal BP decline (non-dippers and dippers) were distinguished (groups ND and D, respectively). Patients with hypertension in group ND had elevation of systolic BP variability during night and day time, augmentation of nocturnal and diurnal HRV low frequency power, lowering of nocturnal high frequency power, lowering of pNN50 and rMSSD values at night. HRV parameters of control subjects in this group did not differ from those of healthy people. All HRV parameters in group D were characterized by significant 24-hour rhythmicity. This rhythmicity was substantially disturbed in patients of group ND. Parameters of central hemodynamics were similar in groups D and ND. CONCLUSION: These results evidence for the presence of enhanced activity of sympathetic part of autonomic nervous system in non-dipper patients with hypertensive disease throughout 24 hours and during night time and for disturbed circadian rhythm of autonomic nervous system activity. This can serve as a basis for increased rate of cardiovascular complications in this category of patients.     

Heart Rate Variability to Assess Changes in Cardiac Vagal Modulation Prior to the Onset of Paroxysmal Atrial Fibrillation in Patients With and Without Structural Heart Disease

Background and Objectives: In patients with paroxysmal lone AF, clinical data indicate a predominance of vagal modulation preceding attacks of the arryhthmia. Systematic data derived from time-domain analysis of HRV evaluating changes in autonomic modulation prior to AF onset are sparse, both in patients without and with evidence for structural heart disease. This study evaluated changes in autonomic modulation prior to the onset of AF in patients with and without structural heart disease. Methods and Results: In 26 consecutive patients with at least one episode of paroxysmal AF preceded by a period of sinus rhythm of at least 8 hours duration documented on Holter monitoring, the time-domain parameters SDNN, rMSSD, and pNN5O were analyzed at different time points between 8 hours and 10 minutes prior to the onset of AF. Fourteen patients had AF associated with structural heart disease, whereas 12 patients had paroxysmal lone AF. Analysis of HRV changes before onset of AF revealed significant differences between the two patient groups: In patients without heart disease, pNN5O and rMSSD increased from 10 ± 3 to 15 ± 4% (P=0.003) and from 38 ± 7 to 53 ± 9 ms (P=0.035). No significant change in HRV was observed in patients with structural heart disease (pNN5O 5 ± 3 vs. 6 ± 2 % and rMSSD 25 ± 4 vs. 28 ± 6 ms). Conclusions: In patients with lone AF, there is a significant shift of autonomic modulation towards a vagal predominance prior to the onset of paroxysmal AF as compared to patients with structural heart disease. Analysis of HRV prior to attacks of AF is useful in determining these triggering mechanisms.     

Norepinephrine and heart rate variability: a marker of dysautonomia in chronic Chagas cardiopathy.

The involvement of the autonomic nervous system (ANS) in Chagas' disease has been the subject of many studies, which have become more numerous since K?berle's pioneering work in the 1950s, showing the partial or total destruction of cardiac neurons. In order to investigate ANS involvement in the pathogenesis of chronic Chagas cardiopathy, seventy-five patients with the condition were examined and divided into four groups, according to the Los Andes classification: I-A, I-B, II and III. Groups I-A and I-B included patients at an early stage of cardiac involvement; group II, patients at an advanced stage without heart failure (HF); and group III, patients at an advanced stage with HF. Norepinephrine (NE) levels were measured in 24 h urine collected from fifty-two chronic Chagas patients (69%); twelve cardiopathic patients of other etiologies, in functional class IV of the New York Heart Association (NYHA), selected as the control group; and ten normal individuals. 24-hour Holter monitoring was performed in fifty-six patients (74.6%) to assess heart rate variability (HRV). HRV parameters were analyzed and distributed according to the Los Andes classification. Norepinephrine levels were significantly higher (p = 0.0001) in the controls (non-Chagas cardiopathic patients, NYHA IV) than in group III (chronic Chagas cardiopathic patients) according to the Los Andes classification. Reduction of HRV was observed in Chagas patients, but unrelated to functional class, and the indices reflecting parasympathetic activity (pNN50 and rMSSD) were increased in our Chagas patients. Our study concluded that the NE levels in Chagas patients in an advanced stage of cardiac involvement (group III) did not rise as in cardiopathic patients of other etiologies with a similar degree of cardiac involvement, which might be interpreted as an impairment of the sympathetic nervous system in the cases studied, but the increased levels of NE in groups I-A and I-B of the Chagas patients can be interpreted as an early impairment of the autonomic nervous system (sympathetic). HRV was reduced in our patients, but the indices reflecting parasympathetic activity (pNN50 and rMSSD) were preserved in almost all Chagas patients. However, the pNN50 index was reduced in group I-A, suggesting that parasympathetic dysautonomia may be an early phenomenon and may precede left ventricular systolic dysfunction.     

2型糖尿病下肢神经病变心率变异性时域指标的昼夜节律

目的 了解糖尿病合并周围神经病变患者的自主神经功能.方法 2008年1月至2009年3月按随机数字表法抽取天津医科大学代谢病医院的117例2型糖尿病患者,分为2型糖尿病不伴下肢神经病变组(糖1组)59例和2型糖尿病伴下肢神经病变组(糖2组)58例.无糖尿病的对照组50例来源于我院健康体检者.受试对象均接受体重指数、收缩压、舒张压、甘油三酯、总胆固醇、高密度脂蛋白胆固醇、低密度脂蛋白胆固醇、空腹血糖、餐后2 h血糖、糖化血红蛋白、空腹胰岛素、稳态模型胰岛素抵抗指数、24 h动态心电图心率变异性(HRV)、乏式动作反应指数、30/15比值、呼吸差的检测.统计学处理采用卡方检验、方差分析、配对秩和检验.结果 (1)糖1组、糖2组患者心动周期标准差(SDNN)、每5 min R-R均值的标准差(SDANN)、每5 min R-R均值的标准差指数(SDNNIDX)、相邻R-R差值的均方根(rMSSD)、24 h内相邻R-R间期相差＞50 ms的个数占总心跳次数的百分比(pNN50),与对照组比较差异有统计学意义(F值分别为94.702、77.786、55.422、56.175、49.110,均P＜0.01);(2)对照组SDNN、rMSSD、pNN50日间节律分别为(113±20)ms、(31±15)ms、4%(0～45%),夜间节律分别为(104±25)ms、(38±18)ms、11%(0～45%),日夜间比较差异有统计学意义(t=2.472、4.629、5.007,均P＜0.05);糖1组SDNN Et间节律为(81±16)ms,夜间节律为(77±19)ms,日夜间节律比较差异无统计学意义(t=1.952,P＞0.05),糖2组SDNN、rMSSD、pNN50日间节律分别为(64±15)ms、(21±19)ms、1%(0～30%),夜间节律分别为(64±20)ms、18(7～97)ms、1%(0～28%),日夜间节律比较差异无统计学意义(t值分别为0.155、1.103、1.328,均P＞0.05).结论 2型糖尿病不伴及伴下肢神经病变组均存在自主神经功能受损,但后者的自主神经功能更明显受损.心率变异性时域指标的昼夜节律可有效判断自主神经损害.     

The Relationship of Heart Rate Variability with Severity and Prognosis of Cirrhosis

Many studies have demonstrated that cirrhosis is frequently associated with autonomic dysfunction. The aim of this study was to test autonomic dysfunction in cirrhotic patients by analyzing heart rate variability (HRV), to determine whether or not the degree of autonomic dysfunction is correlated with the severity of disease, and, also, to compare the changes of HRV between survivor and nonsurvivor groups after 2-year follow-up periods. HRV was analyzed using 24-hr ECG recording in 30 cirrhotic patients and 28 normal controls. The changes in HRV parameters including mean normal-to-normal (N-N) interbeat intervals (mean NN), standard deviation of all N-N intervals (SDNN), standard deviation of the average of N-N intervals for each 5-min period over 24 hr (SDANN), root mean square succesive differences (r-MSSD; msec), and percentage of adjacent N-N intervals that are >50 msec apart (pNN50), all as time domain parameters, were evaluated. The cirrhotic patients were also evaluated according to Child-Pugh classification scores as markers of the disease severity. The time-domain measures of HRV in cirrhotic patients were significantly reduced compared with those in the control group (for all parameters; P < 0.001). The severity of disease was associated with reduced HRV measures (for all parameters; P < 0.001). After the 2-year follow-up periods, HRV measurements in cirrhotic patients were significantly much lower in nonsurvivors than in survivors (P < 0.001 for all). We conclude that increasing severity of cirrhosis is associated with a reduction in HRV. This finding may be an indicator of poor prognosis and mortality for cirrhosis.     

高血压患者心率减速力与室性心律失常

目的研究高血压患者的心率减速力,并分析其与室性心律失常的相关性。方法筛选无糖尿病和其他致自主神经功能损伤疾病的原发性高血压患者180例,以及同期健康体检者60例作为对照组,进行24h动态心电图检查,离线计算DC值、HRV时域指标,最后进行高血压与健康对照人群的对比分析,以及高血压患者的DC值和HRV时域指标与VA的相关性分析。结果高血压患者VA各组的DC值以及HRV时域指标的SDNN、SDANN、rMSSD、PNN50较对照组均显著降低（p〈0.05）,且高血压患者的DC、SDNN和SDANN与VA程度呈负相关（p〈0.05）。结论高血压患者的DC值及HRV明显降低,且DC、SDNN、SDANN和PNN50与高血压患者VA程度呈负相关。早期对自主神经功能紊乱进行干预治疗,可能有利于减少高血压患者VA的发生。     

Changes of Heart Rate Variability After Coronary Bypass Grafting

Background: Heart rate variability (HRV) may serve as a follow-up parameter in patients with coronary artery disease undergoing percutaneous transluminal angioplasty. Several studies have shown significant changes of HRV parameters in the case of restenosis. The value of this method as a prognostic parameter in patients following coronary artery bypass grafting (CABG) is unknown. Methods: In the present study we investigated changes of HRV parameters in patients undergoing CABG to prove whether this method would predict the outcome in these patients. Twenty patients (six female, 14 male, age 51–75 years, mean 62 years) with angiographically documented coronary artery disease (1 × 1-vessel disease, 10 × 2-vessel disease, 9 × 3-vessel disease) were investigated. Eight patients had previous myocardial infarction: 3 × anterior infarction and 5 × inferior infarction. Before and after CABG 24-hour measurement of HRV was performed using Holler monitoring (elapsed time between the two measurements 218 ± 92 days). All patients underwent successful CABG with complete revascularization. The following time domain parameters were calculated: SDNN, SDNN index, SDANN, r-MSSD and pNN50. Results: These parameters showed a significant decrease after CABG (P < 0.05) except rMSSD, which was below the statistic level. The results of the patients without previous myocardial infarction suggested that the parasympathetically influenced paramenters r-MSSD and pNN50 were mainly involved, while in the subgroup with previous myocardial infarction the sympathetically influenced parameters (SDNN, SDANN) were significantly changed. Other variables such as ejection fraction or severity of coronary artery disease did not influence the HRV results. Conclusions: In contratst to patients with revascularization by PTCA, HRV does not seem to be a suitable predictive parameter in patients after successful CABG. Intrinsic operative alterations with injury of cardiac nerves may be responsible for this observation.