Improvement in sympatho-vagal imbalance and heart rate variability in patients with mitral stenosis after percutaneous balloon commissurotomy.

Elevated sympathetic nerve activity in patients with mitral stenosis (MS) may be an index of the severity of the disease. Percutaneous mitral balloon commissurotomy (PMBC) is now a standard treatment for many patients with symptomatic MS. We aimed to show the effects of PMBC on autonomic nervous system activity in the patients with MS by heart rate variability (HRV) analysis. Fifty-four consecutive patients with mitral stenosis and sinus rhythm who underwent percutaneous mitral commissurotomy were enrolled. Apart from significant haemodynamic improvements, mean heart rate (HR), LF day, LF night, LF/HF day and night significantly decreased and SDNN, RMSSD, PNN50, HF day and night significantly increased in the early period after PMBC and these changes were preserved for up to one month. SDNN was positively correlated with left ventricle ejection fraction (LVEF) but negatively correlated with mean valve area (MVA), left atrial (LA) diameter and pressure, right atrial (RA) pressure; LF/HF day ratio was positively correlated with LA diameter and pressure, mean transmitral gradient and negatively correlated with LVEF; LF/HF night ratio was positively correlated with LA pressure and mean transmitral gradient. The increase in SDNN was correlated with the change in LA and RA pressure. The decrease in LF/HF ratio after PMBC was significantly correlated with the changes in the mean transmitral gradient, LA pressure and RA pressure. As a result, the heart rate variability and autonomic nervous system function in patients with mitral stenosis are correlated with the atrial pressures and left ventricular function. These parameters significantly change in the early period after PMBC and are preserved at one month. The improvement in the heart rate variability and sympatho-vagal balance are significantly affected by the early changes in atrial pressures after PMBC.     

Relation between sympathetic overactivity and left atrial spontaneous echo contrast in patients with mitral stenosis and sinus rhythm

BACKGROUND: Spontaneous echo contrast (SEC) is common in patients with mitral stenosis (MS) and presence of SEC in left atrium (LA) is associated with a higher risk of thromboembolism. Recently, an increase in activation of platelets was demonstrated in patients with SEC raising the hypothesis that platelets are involved in the pathogenesis of SEC. In this study, we evaluated effects of autonomic nervous system activity on SEC formation in patients with rheumatic MS and sinus rhythm by heart rate variability analysis. METHODS AND RESULTS: Twenty-six patients with LASEC were compared with 28 patients without LASEC. Mean heart rate, low frequency (LF) and low frequency/high frequency (LF/HF) ratio were significantly higher, standard deviation of all NN (SDNN), root mean square of successive differences (RMSSD), number of NN intervals that differed by more than 50 ms from adjacent interval divided by the total number of all NN intervals (PNN50) and high frequency (HF) values were lower in the patients with LASEC. A standard deviation of all NN intervals <90ms separated the patients with LASEC from control subjects with a sensitivity of 77% and specificity of 90%; a low frequency >79.5 with a sensitivity of 92% and specificity of 90; a low frequency/high frequency ratio >3.7 with a sensitivity of 96% and specificity of 90%. A left atrial diameter >4.3 cm increased the LASEC formation by 3.0 folds, HR >78 beats/min by 6.4 folds, standard deviation of all NN intervals <90 ms by 9.2 folds, a low frequency/high frequency ratio >3.7 by 6.4 folds, sP-selectin>142 by 5.8 folds. Variables affecting sP-selectin levels were LA diameter, mitral valve area, transmitral mean gradient, left ventricular ejection fraction, the presence of mitral regurgitation, HR, standard deviation of all NN intervals, low frequency, high frequency and low frequency/high frequency ratio. CONCLUSION: Sympathetic overactivity and reduced heart rate variability are important determinants for LASEC formation and increased s-P selectin levels. Therefore, platelet activation via increased sympathetic activity may play an important role in pathogenesis of LASEC.     

Do collaterals affect heart rate variability in patients with acute myocardial infarction?

BACKGROUND: The protective effects and the prognostic importance of collaterals during and after acute myocardial infarction (MI) are under debate and heart rate variability (HRV) is a strong predictor of risk of mortality and arrhythmic events after acute MI. We aimed to examine the effects of collateral circulation on HRV in the early period after acute MI. METHODS: Sixty-four patients admitted to our clinics who were diagnosed with acute anterior MI and underwent thrombolytic therapy were enrolled in this study. We applied 24 h Holter monitoring for HRV analysis to all patients and compared the patients with and without collaterals to the infarct-related artery. RESULTS: Mean heart rate, low frequency (LF) (day, night and 24 h) and LF/high frequency (HF) (day, night and 24 h) were higher, SD of all NN intervals (SDNN), root mean square of successive differences (RMSSD), number of NN intervals that differed by more than 50 ms from the adjacent interval divided by the total number of all NN intervals (PNN50) and HF night values were lower in patients without collaterals than in those with collaterals. SDNN was negatively correlated with left anterior descending coronary artery (LAD) stenosis, ventricle score indices and left ventricular ejection fraction (LVEF); LF/HF ratio was positively correlated with ventricle score indices and negatively correlated with LVEF and Thrombolysis in Myocardial Infarction flow grade. Linear regression analysis showed that ventricle score index and coronary collaterals affect HRV and LAD stenosis, ventricle score, LVEF and coronary collaterals affect LF/HF ratio. A SDNN <80 ms increased the development of ventricular arrhythmias in the early period by 4.7 fold, a LF/HF ratio >2.7 increased it by 9.8 fold and a LVEF <35% increased it by 12.8 fold, whereas the presence of well-developed collaterals decreased the arrhythmia development by 2.5 fold. CONCLUSIONS: The collaterals to the infarct-related artery have great impact on HRV, autonomic nervous system activity and the development of ventricular arrhythmias in patients with acute anterior MI. Our results suggest a protective role of collaterals on myocardial electrophysiology in the early period after acute MI.     

Left Atrial Contribution to Left Ventricular Filling in Patients with Mitral Stenosis: Combined Analysis of Transmitral and Pulmonary Venous Flow Velocities

We recorded transmitral and pulmonary venous flow velocities using transthoracic continuous-wave and transesophageal pulsed Doppler echocardiography, respectively, in 36 patients with mitral stenosis who were in sinus rhythm to investigate the left atrial contribution to left ventricular filling in mitral stenosis. The mitral valve area was determined by transthoracic two-dimensional short-axis echocardiography. Patients were classified as having mild stenosis (± 1.5 cm², n = 17) or moderate stenosis (< 1.5 cm², n = 19). The mean pulmonary capillary wedge pressure and left atrial maximal diameter were significantly larger, and left atrial volume change during atrial contraction was significantly smaller in the moderate group than in the mild group. The percent left atrial contribution to left ventricular filling, estimated from the transmitral flow velocity, the peak atrial systolic velocity, and the percent ratio of left atrial systolic regurgitation to left atrial filling, estimated from the pulmonary venous flow velocity, were significantly lower in the moderate group than in the mild group. The percent left atrial contribution to left ventricular filling, the peak atrial systolic velocity, and the percent ratio of left atrial systolic regurgitation to left atrial filling were positively correlated with the mitral valve area and negatively correlated with the mean pulmonary capillary wedge pressure. These results suggest that the left atrial contribution to left ventricular filling in patients with mitral stenosis in sinus rhythm decreases as the severity of valve stenosis increases, and that analysis of the atrial systolic waves of the transmitral and pulmonary venous flow velocities provides important information for evaluation of left atrial systolic performance in patients with mitral stenosis.     

Effects of Cigarette Smoking on Heart Rate Variability and Plasma N‐Terminal Pro‐B‐Type Natriuretic Peptide in Healthy Subjects: Is There the Relationship between Both Markers?

Background: Cigarette smoking increased the risk of acute cardiac events related with endothelial dysfunction and increased sympathetic activity. Impaired autonomic nervous activity is recognized as a considerable symptom of cardiac dysfunction and is strongly associated with increased risk overall mortality. Methods: A total of 75 healthy habitual smokers (40 female, 35 male, mean age 36.5 ± 8.5 years), and 73 non‐smokers subjects (45 female, 28 male, mean age 34.6 ± 7.2 years) were studied. LF and LF/HF ratio were significantly higher in smokers than in non‐smokers. On the contrary, SDNN, SDANN, RMSSD, and HF values were lower in smokers compared to those in non‐smokers. Not the duration of smoking but the number of cigarettes smoked per day was correlated with the HRV parameters and NT‐pro BNP. Furthermore, the average levels of NT‐pro BNP were found to be positively correlated with LF, LF/HF and inversely correlated with SDNN, SDANN, RMSSD and HF. Results: As a result, smoking impaires sympathovagal balance and decreases the heart rate variability in healthy subjects. And even a one cigarette smoking leads to overt sympathetic excitation. Furthermore, smoking results in an increase in NT‐proBNP levels and the changes in adrenergic nervous system and NT‐proBNP levels are well correlated. Conclusion: These findings could contribute to the higher rate of cardiovascular events in smokers.     

X综合征患者自主神经功能观察

为了解X综合征患者中自主神经功能活动。观察8例X综合征患者和10例健康人心率变异有关指标。结果显示:患者R·R间期与正常人无差弹。而SDNN、SDANN、SDNNIndex、PNN_50、rMSSD等时域指标,LF、HF、LF/HF等频域指标均低于正常人。提示X综合征患者的自主神经系统活动不平衡,以交感神经活动占优势。     

Heart Rate Variability in Peritoneal Dialysis Patients: What Is the Role of Residual Renal Function?

Background: The relationship between heart rate variability (HRV) and residual renal function (RRF) has not been elucidated previously. Methods: In this cross-sectional study, HRV was evaluated in 71 peritoneal dialysis patients. Patients were divided into RRF decline group, RRF stable group and anuric group. Results: RRF was negatively correlated with SDNN (r = -0.284, p = 0.017), TP (r = -0.247, p = 0.039), and HF (r = -0.238, p = 0.047). Significant sympathetic nerve activation was found in the RRF decline group (significantly lower SDNN, SDSD, RMSSD, pNN50, LF, HF, TP and higher LF/HF ratio) as compared to the RRF stable and anuric groups. Besides, significantly parasympathetic activation was found in the anuric group (the lowest LF/HF ratio as compared to the other groups (both p < 0.05). Multivariate stepwise regression analysis showed that the status of RRF was an independent factor associated with HRV parameters. Conclusion: This study showed autonomic nervous function in peritoneal dialysis patients was associated with a different status of RRF.     

射频消融术后心脏自主神经的变化对房颤早期复发的影响

目的:通过心率变异性分析,探讨左房环肺静脉消融术对自主神经系统的影响及其与心房颤动(房颤)早期复发的关系。方法:阵发性房颤患者90例,均接受CARTO指导下左房环肺静脉电隔离射频消融术。在术前3 d及术后3 d进行12导联动态心电图(Holter)监测,根据术后随访结果将患者分为房颤复发组(n=38例)和无复发组(n=52例)。并记录两组的平均心率(MeanHR),心率变异性(heart rate variability,HRV)分析,包括时域指标SDNN、SDANN、rMSSD、PNN50,频域指标W、LF、HF、LF/HF,进行比较。结果:90例患者均达到肺静脉电隔离。术后反应迷走神经及交感神经张力的指标均显著降低;在无复发组,反应迷走神经张力的HF降低更显著,LF/HF升高,其它HRV指标均显著降低;在复发组,MeanHR升高,反应交感神经张力的LF显著降低,LF/HF降低。结论:降低迷走神经张力,可能会抑制阵发性房颤患者左房环肺静脉消融术后的早期复发。     

Heart rate variability in patients with stable coronary artery disease and aspirin resistance

Aspirin resistance as defined by failure to effectively inhibit thromboxane synthesis is associated with a higher risk of recurrent myocardial ischemia and cardiovascular death. Heart rate variability (HRV) analysis has been extensively used to identify patients at risk for increased cardiac mortality. The aim of this study was to evaluate the association between HRV and aspirin resistance in patients with stable coronary artery disease (CAD). Sixty-nine (69) consecutive patients with stable CAD were included in this study. Of the 69 patients, 18 (26%) were aspirin nonresponders. When the aspirin responders were compared with the nonresponders, there was no significant difference between the groups with respect to most clinical parameters, major cardiovascular risk factors, medical treatments, and aspirin dosages. However, the patients with aspirin resistance had a higher previous myocardial infarction history and lower left ventricular ejection fraction. Moreover, mean platelet volume, CT/EPI, CT/ADP values, LF and LF/HF ratio were higher while HF, SDNN, SDANN, and RMSSD were lower in the nonresponder group than the responders. Regarding HRV parameters, CT/ADP time was negatively correlated with SDNN (r = -0.5, P = 0.02) and HF (r = -0.4, P = 0.03), and positively correlated with LF (r = 0.6, P = 0.01) and LF/HF (r = 0.7, P = 0.001). Similarly, CT/EPI time was negatively correlated with SDNN (r = -0.4, P = 0.03), and positively correlated with LF (r = 0.5, P = 0.02) and the LF/HF ratio (r = 0.5, P = 0.02). Regression analysis revealed that the only parameters affecting SDNN and LF/HF ratio were left ventricle ejection fraction and aspirin resistance. The heart rate variability decreased and sympathetic activity increased in the patients with aspirin resistance and stable CAD. This may contribute to a higher risk of recurrent myocardial ischemia and cardiovascular death in patients with aspirin resistance.     

Cigarette Smoking and Heart Rate Variability: Dynamic Influence of Parasympathetic and Sympathetic Maneuvers

Background: Cigarette smoking has been associated with increased activity of the sympathetic nervous system. In this study, we investigated cardiac autonomic function in heavy smokers and nonsmoker controls by analysis of heart rate variability (HRV). Method: Twenty‐four long‐term heavy smokers (men) and twenty‐two nonsmoker subjects (hospital staff) were included to study. Time domain [mean R‐R interval (RR), the standard deviation of R‐R interval index (SDNN), and the root mean square of successive R‐R interval differences (RMSSD)] and frequency domain [high frequency (HF) low frequency (LF), and LF/HF ratio] parameters of HRV were obtained from all participants after 15 minutes resting period in supine position (S), during controlled respiration (CR), and handgrip exercise (HGE) over 5‐minute periods. Results: Baseline SDNN and RMSSD values were found to be lower in smokers than in nonsmokers. (64 ± 10 vs 78 ± 22, P < 0.05 and 35 ± 12 vs 54 ± 30 ms, P < 0.05). Baseline LF/HF ratio was also found to be higher in smokers than in nonsmokers (1.3 ± 0.6 vs 0.9 ± 0.5 ms, P < 0.05). The other HRV parameters including R‐R interval, LF, and HF were not significantly different. During CR, expected increase in RR, SDNN, and RMSSD did not occur in smokers, while it did occur in nonsmokers. Most HRV indices were significantly affected by HGE in both groups. In addition, the duration of smoking was found to be inversely correlated with RMSSD and HF and positively correlated with LF/HF ratio. Conclusion: Vagal modulation of the heart is blunted in heavy smokers, particularly during a parasympathetic maneuver. Blunted autonomic control of the heart may partly be associated with adverse event attributed to cigarette smoking.     

Left atrial function as a predictor of haemodynamic response in patients with mitral stenosis: a dobutamine stress echocardiographic study

OBJECTIVE: The mechanisms of the different haemodynamic and clinical responses to dobutamine infusion in mitral stenosis (MS) are not clearly established. The aim of this study was to evaluate the relation between left atrial (LA) function and haemodynamic response in patients with MS during dobutamine infusion. METHODS AND RESULTS: Forty-two consecutive moderately symptomatic patients (33 women, 9 men; mean age 46+/-9, range from 26 to 66), New York Heart Association (NYHA) class II with MS (mean mitral valve area 1.7+/-0.1 cm2) were evaluated with dobutamine stress echocardiography. Haemodynamic measurements were obtained at rest and during peak dobutamine infusion. LA fractional shortening at rest was used as an index of global LA function. Group I consisting of patients with significantly elevated pulmonary artery pressure (> 60 mm Hg) and mean transmitral gradient (> 15 mm Hg) at peak dobutamine infusion were defined as haemodynamically serious MS. Group II consisted of the remaining 30 patients whose haemodynamic data were below these levels. While baseline haemodynamic parameters and mitral valve characteristics were not different between the two groups, LA fractional shortening was significantly lower (18.9+/-2.8 vs. 32.3+/-5.1%, p<0.0001) and left atrial dimension was significantly larger in group I (49.7+/-2.3 mm vs 43.6+/-5.3 mm, p<0.0001). Left atrial fractional shortening was negatively correlated with the increase in mean transmitral gradient (r:-0.58, p<0.01). When the patients were divided using a LA fractional shortening level of 25% as the cut-off point, we observed that the patients with low LA fractional shortening had a greater increase in mean transmitral gradient (7.3+/-3.1 mm Hg vs. 4.6+/-1.4 mm Hg), p = 0.005) and pulmonary artery pressure (22.4+/-3.5 mm Hg vs. 16.1+/-8.5 mm Hg, p = 0.001) compared to the patients with high LA fractional shortening. Based on these haemodynamic results, management was changed in 12 patients (28%): 5 underwent percutaneous mitral balloon commissurotomy and 7 received intensive medical treatment. CONCLUSIONS: The present study demonstrates that haemodynamic response during dobutamine stress echocardiography correlates with LA fractional shortening in patients with MS. The evaluation of left atrial function at rest in patients with ambiguous symptoms and mild mitral stenosis may be useful in clinical decision making. Atrial dysfunction at rest may predict the haemodynamic response during stress echo in these patients.     

自主神经系统在阵发性心房颤动发作前后心率变异性变化中的作用

目的分析阵发性心房颤动发作前后心率变异性的变化,探讨自主神经系统在阵发性心房颤动中的作用。方法采用动态心电图记录28例阵发性心房颤动患者24h心电信息,分析其发作前后5min及白天（6：00～22：00）和夜间（22：00～6：00）的心率变异性指标。结果心房颤动发作前5min平均正常R—R间期的标准差（SDNN）、高频成份（HF）较终止后5min显著升高（P〈0．01）,低频／高频比值（LF／HF）显著降低（P〈0．01）,LF无变化：LF、HF白天均高于夜间（P〈0．01）,白天与夜间SDNN、LF／HF无差异;阵发性心房颤动发作前5minSDNN与阵发性心房颤动发作频率呈正相关（r=0．545。P〈0．01）,LF／HF与阵发性心房颤动发作频率和持续时间呈负相关（r=-0532、-0．563,均P〈0．01）。结论阵发性心房颤动发作前心率变异性升高,迷走神经支配占优势,使心房颤动得以诱发和持续。     

Cardiovascular risk factors significantly correlate with autonomic nervous system activity in children

Background

Information is limited about the correlation between cardiovascular risk factors (CRFs) and autonomic nervous system (ANS) activity in children.

Methods

In all, 180 children aged 9 to 11 years were enrolled. Heart rate variability, obtained by 24-hour Holter recordings, was analyzed for ANS activity by measuring standard deviation of normal-to-normal RR intervals (SDNN), the standard deviation of the averaged normal-to-normal RR intervals, the root mean square of successive differences (RMSSD), low-frequency (LF), high-frequency (HF), and ratio of LF to HF. CRFs were defined as hypertension, dyslipidemia, obesity, and elevated fasting blood glucose. Children were subdivided into 4 levels: 0 (no CRF), 1 (1 CRF), 2 (2 CRFs), or 3 (3 or more CRFs). Altered ANS activity of each level was assessed. The correlation between CRF and ANS activity was analyzed by stepwise multiple regression.

Results

With an increasing number of CRFs, there was a progressive elevation in blood pressure, obesity indices, most blood lipoprotein concentrations, and fasting blood glucose. Moreover, increase in the number of CRFs was associated with progressive reduction of SDNN, RMSSD, LF, and HF. Systolic blood pressure (SBP) correlated negatively with SDNN, RMSSD, LF, and HF. Obesity indices had a negative correlation with RMSSD and HF. As the number of CRFs increases, so does the extent of abnormal clustering of CRFs and changes in ANS activity.

Conclusions

Obesity and elevated SBP are associated with marked alterations in ANS activity, obesity with reduced vagal nerve activity, and elevated SBP with altered vagal and sympathetic nerve activity.     

Left atrial function, cytokines and soluble apoptotic markers in mitral stenosis: effects of valvular replacement

BACKGROUND: Patients with mitral stenosis (MS) and heart failure (HF) are characterized by changes in the left atrial (LA) function and activation of the apoptotic process. The purpose of the present study was the evaluation of the effect of mitral valve replacement on the LA function, on inflammatory process and apoptotic markers in patients with MS and HF. METHODS: We studied 30 patients with MS and HF (15 in NYHA III-IV and 15 in NYHA IV) in sinus rhythm (mean age 56.2 +/- 4.6 years), and 20 age and gender matched healthy volunteers. Blood samples were obtained before and 6 months after surgical mitral valve replacement, and plasma levels of soluble Fas/APO-1 receptor (sFas), tumor necrosis factor-alpha (TNF-a) and interleukin-6 (IL-6) were measured. Echocardiographically, LA volumes were measured at mitral valve opening (Vmax), at the onset of left atrial systole (P wave of the electrocardiogram, Vp) and at the mitral valve closure (Vmin). LA contractile function was assessed by the LA active emptying fraction (ACTEF). RESULTS: After mitral valve replacement, TNF-a, IL-6 and sFas levels, as well as the Vmax LA volume, were significantly reduced (p < 0.05). ACTEF showed a significant postoperative decrease (0.29 +/- 0.09 vs. 0.23 +/- 0.06, p < 0.01) and it was significantly correlated with sFas (r = -0.88, p = 0.001), TNF-a (r = -0.81, p = 0.001) and IL-6 (r = -0.74, p = 0.001) levels. CONCLUSION: The present findings indicate that mitral valve replacement in patients with mitral valve stenosis, reduces the size of the left atrium, improves left atrial contractile function and depresses inflammatory and apoptotic process.     

阵发性心房颤动发作前后心率变异性的变化

目的探索自主神经活动在阵发性心房颤动中的作用.方法在动态心电图上测量分析了25例阵发性房颤患者53阵次心房颤动发作前后及白天(6:00～22:00)和夜间(22:00～6:00)的心率变异指标(SDNN、LF、HF、LF/HF)的变化.结果房颤发作前1h SDNN、HF较终止后1h显著升高(p＜0.01),LF/HF显著降低(p＜0.01),LF无变化;LF、HF白天均高于夜间(分别为p＜0.05和p＜0.01),夜晚LF高于HF(p＜0.05),白天与夜间SDNN、LF/HF无差异,白天LF与HF无差异.结论阵发性心房颤动患者存在着明显的自主神经功能失常,特别是白天迷走神经张力增强;迷走神经张力增强是阵发性房颤的重要原因.     

弥漫性甲状腺肿治疗前后心率变异性的变化

目的 探讨弥漫性甲状腺肿（又称Graves病,简称GD）患者心率变异性（HRV）的变化。方法 选取30例GD患者,另选取30例健康志愿者作为对比研究。观察GD患者治疗前后HRV指标：所有窦性心搏RR间期标准差（SDNN）、全程记录中每5 min窦性心搏RR间期平均值的标准差（SDANN）、相邻RR间期差大于或等于50 ms的个数占总心跳次数的百分比（PNN50）、低频LF（0. 04 ~ 0. 15 Hz）、高频HF（0. 15 ~ 0. 40 Hz）、LF/ HF值、极低频VLF（0. 003 3 ~0. 04 Hz）。结果 GD组治疗后与治疗前相比,时域指标：SDNN、RMSDNN、SDANN、PNN50均改善（P 均〈0. 01）;频域指标LF、HF、VLF亦均明显改善（P 均〈0. 01）;GD组治疗前HRV指标：SDNN、PNN50、LF、HF、VLF均低于对照组（P〈0. 01）;GD组治疗后与对照组相比,HRV上述指标两组无显著性差异。 GD组治疗前频域指标24 h波动曲线趋于平稳,治疗后波动性有所恢复。结论 GD患者存在心脏自主神经调节功能异常,以迷走神经受损为主;24 h频域指标波动性则趋于平稳,治疗后调节功能异常和波动性可有不同程度恢复。     

原发性高血压合并2型糖尿病患者心率变异性与心脏变时功能不全的特点及相关性

目的 探讨原发性高血压合并2型糖尿病患者的心率变异性和心脏变时功能不全特点. 方法 原发性高血压合并2型糖尿病患者与健康人各40例,行24 h动态心电图检查,计算心脏变异性指标SDNN、SDANN、RMSSD、PNN50;行平板运动试验检查,计算运动中最大心率、心脏变时指数、心率储备率,分析心脏变时指数和心率储备率与SDNN、SDANN、RMSSD、PNN50的相关性. 结果 原发性高血压合并2型糖尿病患者SDNN、SDANN 、RMSSD、PNN50均较健康者降低（P〈0.01）.最大心率、心脏变时指数、心率储备率明显低于健康者（P〈0.01）;SDNN、SDANN、RMSSD及PNN50与心脏变时指数（r=0.522、0.472、0.337、0.321）和心率储备率（r=0.541、0.480、0.351、0.285）均存在明显正相关. 结论 原发性高血压合并2型糖尿病患者心脏自主神经受损明显,表现为迷走神经功能减退和交感神经兴奋性增高.     

Increased sympathetic nervous system activity as cause of exercise-induced ventricular tachycardia in patients with normal coronary arteries

In this prospective study, we set out to determine whether analysis of heart rate variability (HRV) in patients with exercise-induced ventricular tachycardia (EIVT) and normal coronary arteries would reveal increased sympathetic nervous system activity. From January 1996 to December 2001, we compared 16 patients with EIVT and normal coronary arteries with an age- and sex-matched control group. Analysis of HRV showed that parameters indicative of parasympathetic activity were lower in our study group than in our control group: standard deviation of the mean of qualified NN intervals (SDNN), 81.6 +/- 14.5 vs 139.3 +/- 11.0, P <0.001; root mean square of successive differences (RMSSD), 22.3 +/- 4.8 vs 36.3 +/- 6.6, P <0.001; number of NN intervals that differed by more than 5 ms from the adjacent interval, divided by the total number of NN intervals (PNN50), 4.8 +/- 1.5 vs 10.2 +/- 3. 1, P <0.001; and high-frequency component (HF), 28.7 +/- 2.5 vs 32.4 +/- 3.9, P <0.05. Conversely, parameters indicative of sympathetic activity were higher in patients with EIVT: low-frequency component (LF), 71.2 +/- 5.0 vs 52.0 +/- 5.8, P <0.001; and absolute low/high frequency component ratio (LF/HF), 2.7 +/- 0.2 vs 1.6 +/- 0.2, P <0.001. There was a positive correlation between EIVT and LF (r=0.79, P <0.001) and between EIVT and LF/HF (r=0.81, P <0.001). Our results suggest the presence of increased sympathetic and decreased parasympathetic tone in patients with EIVT. We conclude that EIVT is associated with an imbalance in the autonomic nervous system.     

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     

Sympathetic Overactivity in Patients with Pulmonary Stenosis and Improvement after Percutaneous Balloon Valvuloplasty

Objective : Percutaneous balloon valvulotomy (PBV) is the procedure of choice for the treatment of valvular pulmonary stenosis (PS) with similar results comparable to surgical valvotomy but less invasive. . Methods and Results : Twenty‐seven consecutive patients with PS being evaluated for PBV were enrolled in the study. Peak instantaneous transvalvular gradient, right ventricle (RV) diameter, mean atrial pressures, RV systolic pressure (RVSP), pro‐brain natriuretic peptide (proBNP) levels significantly decreased immediately after PBV. Regarding heart rate variability (HRV) parameters, mean HR (heart rate), LF (low frequency) day and night, LF/HF day and night significantly decreased and standard deviation of all NN intervals (SDNN), root mean square of successive differences (RMSSD), P number of NN intervals that differed by more than 50 ms from adjacent interval divided by the total number of all NN intervals (PNN50), HF (High frequency) day and night significantly increased 1 day after PBV and these changes were shown to be preserved at the first month. The increase in SDNN was correlated with the decrease in right atrial pressure (RAP) (r =?0.5, P = 0.04); the increase in standard deviation of the 5‐minute mean RR intervals (SDANN) was correlated with the decrease in proBNP (r =?0.4, P = 0.03). Conclusions : Sympathetic overactivity and increased proBNP levels were associated with the symptomatic status of patients with PS. Associated with a decrease in atrial pressures and proBNP levels, PBV yielded a decrease in adrenergic overactivity in the patients with PS.