Cardiac resynchronization therapy upregulates cardiac autonomic control

Objective: To determine the effect of cardiac resynchronization therapy (CRT) on sympathetic nervous function in heart failure (HF). Background: Neurohormonal dysregulation and cardiac autonomic dysfunction are associated with HF and contribute to HF progression and its poor prognosis. We hypothesized that mechanical resynchronization improves cardiac sympathetic function in HF. Methods: Sixteen consecutive patients receiving CRT for advanced cardiomyopathy and 10 controls were included in this prospective study. NYHA class, 6‐minute walk distance, echocardiographic parameters, plasma norepinephrine (NE) were assessed at baseline, 3‐month and 6‐month follow‐up. Cardiac sympathetic function was determined by ¹²³iodine metaiodobenzylguanidine (¹²³I‐MIBG) scintigraphy and 24‐hour ambulatory electrocardiography. Results: Along with improvement in NYHA class (3.1 ± 0.3 to 2.1 ± 0.4, P < 0.001) and LVEF (23 ± 6% to 33 ± 12%, P < 0.001), delayed heart/mediastinum (H/M) ¹²³I‐MIBG ratio increased significantly (1.8 ± 0.7 to 2.1 ± 0.6, P = 0.04) while the H/M ¹²³I‐MIBG washout rate decreased significantly (54 ± 25% to 34 ± 24%, P = 0.01) from baseline to 6‐month follow‐up. The heart rate variability (HRV) measured in SD of normal‐to‐normal intervals also increased significantly from baseline (82 ± 30 ms) to follow‐up (111 ± 32 ms, P = 0.04). The improvement in NYHA after CRT was significantly associated with baseline ¹²³I‐MIBG H/M washout rate (r = 0.65, P = 0.03). The improvement in LVESV index was associated with baseline ¹²³I‐MIBG delayed H/M ratio (r =?0.67, P = 0.02) and H/M washout rate (r = 0.65, P = 0.03). Conclusion: After CRT, improvements in cardiac symptoms and LV function were accompanied by rebalanced cardiac autonomic control as measured by ¹²³I‐MIBG and HRV.     

Prognostic Significance of Heart Rate Variability During the First 24 Hours of Acute Myocardial Infarction: A 5‐Year Follow‐up Study

Background: The prognostic value of heart rate variability (HRV) measured within the first 24 hours of acute myocardial infarction was assessed in 94 consecutive patients. Methods: The mean of standard deviation of normal R‐R intervals for all 5‐minute segments (SDNN index), the width of the R‐R interval histogram at 10% and 50% of the peak, and three frequency‐domain measures of HRV (low frequency [LF], high frequency [HF], and LF/HF ratio) were calculated from a continuous ECG recording taken within the first hours of admission and their prognostic value for long‐term events was studied. Results: During the follow‐up period (56.7 ± 5.9 months) 6 sudden and 7 nonsudden cardiac deaths occurred. Time‐domain measurements of HRV were lower in patients with sudden death (SDNN index: 27.0 ± 20.2 vs 47.5 ± 20.7 ms in survivors, P < 0.001). LF and HF power, but not the LF/HF ratio, were also inversely associated with sudden death. No significant differences were found between survivors and patients with nonsudden cardiac death. After adjustment for other clinical covariates, LF and HF power remained significantly associated with sudden death. Conclusion: We conclude that heart rate variability measured within the first 24 hours of myocardial infarction is a strong predictor of sudden death during subsequent follow‐up.     

Heart Rate Variability After Coronary Artery Bypass Graft Surgery: A Prospective 3‐Year Follow‐Up Study

Background: Autonomic heart rate control is impaired after CABG. The aim of this study was to establish the temporal pattern of change in the decrease of HRV observed after CABG. Methods and Results: Twelve patients with coronary artery disease were assessed with 24‐hour Holter recordings 2 days before CABG and 1 week, 3 months, 6 months, 1 year, and 3 years after CABG. All the time‐domain and frequency‐domain HRV parameters decreased precipitately after CABG and were mostly recovered 3 months after CABG except mean NN, rMSSD, and pNN50. The ratio of LF to HF showed a slight decrease after surgery, recovered to preoperative values after 3 months, surpassed, and continued to increase 6 months after surgery. At 3 years of follow‐up the recovery was complete. The rate of change of time‐domain and frequency‐domain parameters were calculated and their correlation with aortic cross‐clamping time, number of vessels bypassed, the amount of cardioplegic used were sought and no statistically significant correlation was found. Conclusion: The recovery of HRV regardless to the preoperative state of the patients and their postoperative course implies that the early drop of HRV after CABG was related to the acute effects of surgery. Late complete recovery of HRV may be due to resolution of ischemia or use of angiotensin‐converting enzyme inhibitor. A.N.E. 2002;7(3):247–250     

Factors influencing heart rate variability in patients with severe aortic valve disease

Background and hypothesis: Heart rate variability (HRV) is an accepted tool for the assessment of cardiovascular autonomic tone. There are no sufficient data concerning its application to patients with severe aortic valve disease (AVD) requiring cardiac surgery. Methods: It was the aim of this study to examine HRV and its physiologic correlates in patients with severe aortic valve disease requiring cardiac surgery. The correlates of time domain indices of HRV obtained from 24-h Holter electrocardiographic recordings were analyzed in 36 consecutive patients (23 men and 13 women, mean age 62 ± 11 years) with AVD prior to cardiac surgery (aortic stenosis: 17 patients, aortic valve regurgitation: 3 patients, combined aortic valve disease: 16 patients). Results: Low values of HRV were found in the entire study group: SDNN 96.8 ± 30.9 ms, SDNNI 39.3 ± 14.4 ms, SDANN 86 ± 28.9 ms, and RMSSD 30 ± 18.1 ms. In a univariate analysis, there was no significant correlation between the time domain measures of HRV and age, gender, medication, left ventricular ejection fraction, peak aortic pressure gradient, fraction of aortic valve regurgitation, and left ventricular mass assessed by echocardiography. Patients in advanced functional classes of heart failure [New York Heart Association (NYHA) III or IV] had significantly lower values for SDNN (83.8 ± 33.6 vs. 107.3 ± 24.7 ms; p<0.05) and SDANN (72.7 ± 29.4 vs. 96.6 ± 24.3 ms; p<0.05) than patients in NYHA class I or II. Reassessment of HRV 1 week after aortic valve replacement was performed in 17 patients and showed a significant further decrease of SDNN (102.4 ± 29.7 vs. 61.5 ± 23.5 ms; p<0.001), SDNNI (40.7 ± 13.6 vs. 23.4 ± 12.4 ms; p<0.001) and SDANN (91.8 ±29.2 vs. 54.2 ± 22.8 ms;p<0.001). Conclusion: Patients with AVD requiring cardiac surgery reveal reduced time domain indices of HRV. This observation is pronounced in patients with a progressed clinical class of heart failure, whereas hemodynamic and echocardiographic parameters seem to have no significant influence on HRV parameters in this population. In addition, there is evidence of a further reduction of HRV time domain indices 1 week after uncomplicated aortic valve replacement.     

Association Between Left Ventricular Mechanics and Heart Rate Variability in Untreated Hypertensive Patients

The authors sought to investigate left ventricular (LV) mechanics and heart rate variability (HRV), and their relationship, in untreated hypertensive patients. A total of 63 untreated hypertensive patients and 45 healthy patients were included. All patients underwent 24‐hour Holter monitoring and echocardiographic examination (two‐ and three‐dimensional). All parameters of time and frequency domain of HRV were decreased in the hypertensive patients. Two‐dimensional LV longitudinal and circumferential deformation was significantly reduced in hypertensive patients. Three‐dimensional LV strain in all three directions as well as area strain were reduced in the hypertensive group. In two different models of multivariate regression, two‐dimensional LV longitudinal and circumferential strain, as well as three‐dimensional LV area strain, remained associated with HRV parameters independently of LV structural and functional parameters. This study showed that LV mechanics and HRV were significantly impaired in untreated hypertensive patients. Two‐ and three‐dimensional echocardiographic LV deformation were independently associated with HRV parameters in the whole study population.     

The effects of metoprolol and captopril on heart rate variability in patients with idiopathic dilated cardiomyopathy.

BACKGROUND: The effects of treatment with captopril or metoprolol on heart rate variability (HRV) were investigated in 38 patients (29 men and 9 women) with mild to moderate symptoms of heart failure due to idiopathic dilated cardiomyopathy (DCM). HYPOTHESIS: The aim of the study was to investigate and compare the effects of the angiotensin-converting enzyme inhibitor captopril with those of the selective beta-adrenergic receptor blocker metoprolol on HRV in patients with idiopathic DCM. METHODS: Heart rate variability was analyzed in the time and frequency domains from 18th of Holter monitoring before randomized treatment was started, after 6 months of therapy, and 1 month after therapy was stopped. RESULTS: Captopril treatment increased HRV expressed as total power and low-frequency power in the frequency domain. There was no change in the time domain. In the metoprolol group, there was a pronounced increase in both time- and frequency-domain indices of HRV. The increase in total power was partly maintained 1 month after therapy was stopped in both treatment groups. CONCLUSION: Treatment with captopril and metoprolol increases HRV in patients with DCM. This effect seems to be maintained for at least 1 month after therapy is stopped. The increase in HRV seems to be more pronounced with metoprolol, and the two different pharmacologic approaches may have additive effects that are of prognostic importance in patients with heart failure.     

Effect of Beta‐Blockade on Autonomic Modulation of Heart Rate and Neurohormonal Profile in Decompensated Heart Failure

Background: One of the putative mechanisms for the salutary effects of beta‐blockers in patients with congestive heart failure (CHF) is their ability to improve autonomic dysfunction. However, patients with profound neurohumoral abnormalities derive little survival benefit from beta‐blockers. The purpose of the current study was to evaluate the effect of beta‐blockers on heart rate variability (HRV) in decompensated CHF. Methods: Time and frequency domain HRV indices were obtained from 24‐hour Holter recordings and compared to assess the role of beta‐blockade in 199 patients (mean age 60 ± 14 years) with decompensated CHF. Neurohormonal differences were assessed by measuring norepinephrine, endothelin‐1, tumor necrosis factor‐a, and interleukin‐6 in a subset of 64 patients. Results: All HRV indices were markedly suppressed but were substantially higher in patients who were on beta‐blockers. Time domain measures of parasympathetic cardiac activity, the percentage of R‐R intervals with > 50 ms variation (4.9 ± 0.6 vs 7.7 ± 1.2%, P = 0.006) and the square root of mean squared differences of successive R‐R intervals (22.7 ± 2.0 vs 31.6 ± 4.1 ms, P = 0.004), were higher in the beta‐blocker group. Spectral analysis revealed that the total power and the ultra‐low frequency power were significantly higher in patients on beta‐blockers (82% and 59%, respectively). The high frequency power, a spectral index of parasympathetic modulation, was 41% higher in the beta‐blocker group (121 ± 25 vs 171 ± 27 ms2, P = 0.02). Norepinephrine and interleukin‐6 levels were substantially lower in patients on beta‐blockers (28% and 61%, respectively). However, these differences did not reach statistical significance. Conclusions: Beta‐blockers improve the impaired cardiac autonomic regulation during high sympathetic stress of decompensated CHF. This effect may play an important role in protecting the myocardium and preventing arrhythmias during transient increases in sympathetic activity. A.N.E. 2001;6(2):98–106     

The Relationship Between Heart Rate Recovery and Heart Rate Variability in Coronary Artery Disease

Background: Reduced heart rate recovery (HRR) in coronary artery disease (CAD) is predictive of increased cardiovascular mortality and is related to reduced parasympathetic tonus. Objective: To investigate HRR and heart rate variability (HRV) measured at steady state condition and the relationship between these two parameters in CAD. Materials and Methods: In our study, we enrolled 33 (28 males, mean age 52.4 ± 9.6 years) patients with CAD who did not have heart failure, atrial fibrillation, pacemaker, and any disease state that could affect the autonomic functions and 38 age‐matched healthy subjects (21 males, mean age 48.3 ± 7.8 years). All the patients underwent submaximal treadmill exercise testing (Bruce protocol). HRR was calculated by subtracting the heart rate values at the 1st, 2nd, and 3rd minutes of the recovery phase from the peak heart rate (HRR₁, HRR₂, HRR₃). Before exercise testing, short‐term steady state HRV analyses of all subjects were obtained with the time‐ and frequency‐domain methods and were correlated to HRR. For frequency‐domain analysis, low‐frequency HRV (LF, 0.004–0.15 Hz), high‐frequency HRV (HF, 0.15–0.5 Hz), and LF/HF ratio were measured for 5 minutes in the morning. For time‐domain analysis, standard deviation of the normal‐to‐normal NN intervals (SDNN), square root of the mean squared differences of successive N‐N intervals (RMSSD), and proportion derived by dividing the number of interval differences of successive N‐N intervals greater than 50 ms by the total number of N‐N intervals (pNN50) were obtained. Only HRR₃ was used for the correlation analysis. Results: In CAD groups, the HF, an indicator of parasympathetic activation, was significantly reduced, whereas the LF and LF/HF values, which are indicators of sympathetic activity, were increased (P = 0.0001 for each parameter). The time‐domain parameters SDNN, RMSSD, and pNN50 were significantly reduced in the patient group (P = 0.0001, P = 0.009, and P = 0.0001, respectively). Similar to the HRV parameters, the HRR₁, HRR₂, and HRR₃ values were significantly reduced in the patient group (P = 0.0001 for each parameter). We observed a significant negative correlation between HRR₃ and LF (r =?0.67, P = 0.0001) and between HRR₃ and LF/HF (r =?0.62, P < 0.0001), while there was a significant positive correlation between HRR₃ and HF, SDNN, RMSSD, and pNN50 (r = 0.69, P = 0.0001; r = 0.41, P = 0.0001; r = 0.31, P = 0.008; and r = 0.44, P = 0.0001). Conclusions: HRR and HRV are significantly reduced in CAD. The reduction in HRR is parallel to the changes in HRV parameters. HRR, which can be measured easily in the recovery phase of exercise testing, can be used to detect the depression of parasympathetic tonus and to evaluate the basal autonomic balance in this patient group.     

Changes in heart rate variability are correlated to hemodynamic improvement with chronic CARVEDILOL therapy in heart failure

BACKGROUND: Reduced heart rate variability (HRV) has been shown to predict mortality in heart failure (CHF). The relationship between improved cardiac function and improvement in HRV has not been previously studied. METHODS AND RESULTS: This was substudy of a randomized, placebo-controlled, double-blinded trial of carvedilol of four months duration. Analysis of HRV was performed on 24-hour Holter monitors obtained at baseline and completion of study. All subjects had symptomatic CHF and an left ventricular ejection fraction (LVEF) <0.35. Study medication was titrated over 1 month to 50 mg/day (< or =75 kg) or 100 mg/day (<75 kg). A total of 17 subjects were randomized to carvedilol and 12 to placebo. Treatment with carvedilol was associated with significant increases in total frequency power, very low frequency power, high frequency power, SDNN, the root-mean square of difference of successive RRs, and pNN50. Change in time and frequency domain measures of HRV had a positive correlation with change in LVEF and negative correlation with change in coronary sinus norepinephrine levels. CONCLUSION: Carvedilol therapy in patients with CHF significantly increased HRV. Change in HRV correlates to improved hemodynamics. This suggests that carvedilol therapy partially normalizes autonomic modulation of heart rate in patients with CHF.     

Effects of Hormone Replacement Therapy on Heart Rate Variability in Postmenopausal Women

Background: Hormone replacement therapy (HRT) is associated with reduced cardiovascular risk, but the underlying mechanism(s) are not fully understood. This study investigated the effects of a 6‐month course of HRT on cardiac autonomic function parameters assessed by heart rate variability (HRV) in postmenopausal women. Methods: Forty‐six healthy postmenopausal women (age 48 ± 5, range 40–60) with normal baseline electrocardiogram and negative exercise testing were enrolled. HRT, which was either 0.625 mg/day conjugated equine estrogen (CEE) plus 2.5 mg/day medroxyprogesterone acetate or 0.625 mg/day CEE alone were administered depending on hysterectomy status. Power spectral analysis of HRV was performed to calculate the low frequency component in absolute (LF) and normalized units (LF nu), high frequency component in absolute (HF), and normalized units (HF nu), and the LF/HF ratio. The standard deviation of RR intervals (SDNN) was calculated from the time series of RR intervals. Results: A 6‐month course of HRT did not significantly alter resting heart rate (P > 0.05). The LF/HF ratio and LF nu significantly decreased after HRT (P = 0.022 and P = 0.032), whereas a significant increase was noted in the HF component of HRV (P = 0.043), indicating an improvement in cardiac autonomic function. The SDNN value, which was 28.8 ± 11.8 ms before HRT significantly increased to 35.4 ± 16.7 ms after 6 months (P = 0.011). Conclusion: Our results indicate that a 6‐month course of HRT may significantly improve cardiac autonomic function parameters, a finding that could at least partly explain the potential cardiopro‐tective effect(s) of HRT. A.N.E. 2001;6(4):280–284     

Circadian Rhythms of Heart Rate Variability in Hypertrophic Cardiomyopathy

Background: It has been hypothesized that an interaction between sympathetic nervous activity and an abnormal myocardium plays a role in the development and progression of hypertrophic cardiomyopathy (HCM). Methods: In the present study we investigated cardiac autonomic function by 24-hour spectral analysis of heart rate variability (HRV) in 18 patients with HCM, without evidence of heart failure, and 18 controls of similar age. Results: We found a significant reduction of 24 hour variance in HCM patients relative to controls (15,000 ± 9480 ms² vs 24,720 ± 12,450 ms² respectively; p < 0.05). Moreover, a loss of the expected day-night changes in the low frequency (LF) spectral component (expressed in normalized units), and LF/HF ratio (HF; high frequency component) were observed in HCM patients. Decreased day-night changes in LF/HF ratio were previously reported in patients with mild hypertension, uncomplicated coronary disease, and after myocardial infarction, conditions in which it seems to exist a higher than normal sympathetic activity. No significant correlations were found between HRV indices and echocardiographic standard measures of systolic and diastolic function parameters. Conclusions: These data are consistent with the presence of an alteration in neural modulation of heart period in HCM patients, noninvasively detectable by continuous 24 hour HRV analysis.     

Echocardiographic predictors of change in left ventricular diastolic pressure in heart failure patients receiving nesiritide

Background: To evaluate the usefulness of currently accepted echocardiographic parameters of diastolic function to assess the acute change in left ventricular end‐diastolic pressure (LVEDP) following the administration of nesiritide in a heart failure population. Methods: In 25 heart failure patients (15 with systolic dysfunction, 10 with preserved ejection fraction [EF]), Doppler echocardiography, right and left heart catheterization, and invasive biventricular pressure hemodynamics were obtained at baseline and 30 minutes after nesiritide infusion. Results: Twenty‐four patients had sufficient echocardiographic images for analysis. The mean age was 60 ± 11 years, 48% were male, 56% had coronary artery disease, and 64% had hypertension. Right ventricular systolic pressure (RVSP) had the highest correlation with LV filling pressure: pulmonary capillary wedge pressure (PCWP), pre‐A wave LV, and LVEDP (r = 0.66, P = 0.0009; r = 0.63, P = 0.002; r = 0.72, P = 0.0002, respectively). Following nesiritide administration, the mean PCWP decreased from 17.1 ± 7.8 mmHg at baseline to 9.6 ± 6.2 mmHg (P < 0.001). Change in RVSP had the highest correlation with change in PCWP (r =?0.67, P = 0.10) and change in LVEDP (r =?0.71, P = 0.07). Conclusion: Echocardiographic parameters are frequently assessed in attempts to estimate left heart diastolic pressures. In heart failure patients, RVSP appears to be the best predictor of LVEDP, outperforming tissue Doppler E/E′. RVSP was found to be the best echocardiographic predictor of change in LV filling pressure with intravenous vasodilator therapy in heart failure patients. RVSP may provide a noninvasive means of assessing response to cardiac therapy.     

Structural,Functional and Autonomic Changes in the Cardiovascular System in Growth Hormone Deficient Patients

Background: Growth hormone deficiency (GHD) is known to cause higher rates of cardiovascular mortality. The purpose of the study was to analyze the structural and functional changes in the heart and investigate their relation to autonomic function as assessed with heart rate variability (HRV). Methods: Eleven untreated GHD patients (mean age 50.4 ± 10.7 years, M/F: 3/8) and 15 age‐ and sex‐matched healthy persons (mean age 45.3 ± 10.4 years, M/F: 5/10) were compared. Both groups were examined with echocardiography, HRV, and exercise testing and findings were analyzed. Results: The groups were similar in height, weight, body mass index, body surface area, systolic and diastolic blood pressure, heart rate. The GHD patients had lower exercise duration and metabolic equivalent (MET) compared to controls (7.94 ± 1.26 vs. 9.8 ± 1.9 min, P < 0.001, for MET 8.85 ± 0.86 vs. 10.7 ± 2.23, P = 0.03). On echocardiography, GHD patients had lower interventricular septum diastolic diameter (9 ± 0.89 vs. 10.7 ± 0.88 mm, P < 0.001) and posterior wall thickness (8.4 ± 0.93 vs. 9.8 ± 0.91 mm, P = 0.002), and lower left ventricle mass index (90.9 ± 20 vs. 112 ± 8 g/m², P = 0.01). Left ventricular ejection fraction was lower in the GHD patients (57.4 ± 5.12% vs. 65.5 ± 4.1%, P < 0.001). Time and frequency domain heart rate variability parameters, SDNN, SDANN, VLF, LF ve LF/HF were lower in GHD patients compared to controls. There was a significant correlation between left ventricle diastolic diameter and LF (r = 0.62, P = 0.02). Conclusion: GHD seemed to cause decreased left ventricle mass and decreases in the sympathetic components of HRV that may have a bearing on the increased cardiovascular risk seen in these patients.     

扩张型心肌病患者心率变异性及其相关因素的研究

目的 :借助心率变异性 (HRV)分析的方法了解扩张型心肌病 (DCM )患者自主神经系统受损状况及其相关因素 ,初步探讨DCM患者心血管事件高发的原因。 方法 :DCM患者 2 5例 ,临床评价心功能NYHAⅡ～Ⅳ级 ;Holter监测 2 4h ,2 3:0 0～ 5 :0 0为夜间 ,室性心律失常按Lown法分级 ,并行 2 4h长程及昼夜的HRV频域、时域分析 ;超声心动图测量左房与左室舒张末期直径、射血分数、E/A峰比值等。比较DCM患者HRV指标与国人正常参考值之间的差异 ;比较DCM患者昼夜HRV指标差异 ;计算DCM患者 2 4hHRV指标与临床参数的相关性。结果 :DCM患者的 2 4hHRV指标除低频外 ,其余均显著低于正常参考值 ;DCM患者的昼、夜HRV指标无差异 ;DCM患者的 2 4hHRV指标中仅SDNN与左心房大小存在中度负相关性 (r =- 0 .4 9) ,其余HRV指标与临床参数之间无统计学相关性。结论 :DCM患者在总体心率变异显著降低的基础上 ,以迷走神经张力低下和HRV昼夜节律性丧失为突出表现 ;且HRV的变化与心腔大小、心功能等多项临床参数之间无相关性 ,它们各自均为DCM患者发生心血管事件的独立危险因子。     

Heart rate variability in idiopathic dilated cardiomyopathy: relation to disease severity and prognosis.

OBJECTIVE: To assess the clinical importance of heart rate variability (HRV) in patients with idiopathic dilated cardiomyopathy (DCM). PATIENTS AND METHODS: Time domain analysis of 24 hour HRV was performed in 64 patients with DCM, 19 of their relatives with left ventricular enlargement (possible early DCM), and 33 healthy control subjects. RESULTS: Measures of HRV were reduced in patients with DCM compared with controls (P < 0.05). HRV parameters were similar in relatives and controls. Measures of HRV were lower in DCM patients in whom progressive heart failure developed (n = 28) than in those who remained clinically stable (n = 36) during a follow up of 24 (20) months (P = 0.0001). Reduced HRV was associated with NYHA functional class, left ventricular end diastolic dimension, reduced left ventricular ejection fraction, and peak exercise oxygen consumption (P < 0.05) in all patients. DCM patients with standard deviation of normal to normal RR intervals calculated over the 24 hour period (SDNN) < 50 ms had a significantly lower survival rate free of progressive heart failure than those with SDNN > 50 ms (P = 0.0002, at 12 months; P = 0.0001, during overall follow up). Stepwise multiple regression analysis showed that SDNN < 50 ms identified, independently of other clinical variables, patients who were at increased risk of developing progressive heart failure (P = 0.0004). CONCLUSIONS: HRV is reduced in patients with DCM and related to disease severity. HRV is clinically useful as an early non-invasive marker of DCM deterioration.     

Relationship between Autonomic Nervous System Activity and Lower Urinary Tract Symptoms: An Analysis of Heart Rate Variability in Men with Lower Urinary Tract Symptoms

Objectives: Lower urinary tract symptoms (LUTS) are common, but their etiology and mechanism remain unclear. We believe that changes in autonomic nervous system (ANS) activity may be contributory because the lower urinary tract is regulated through the sympathetic and parasympathetic nervous systems. Heart rate variability (HRV) is a tool by which autonomic nervous function can be measured; therefore, we measured and compared parameters of heart rate variability between men with LUTS and asymptomatic subjects. Methods: We studied 35 men with LUTS (mean age 50.5 ± 14.9 years) and 110 asymptomatic male volunteers who had requested a health check up (mean age 49.5 ± 5.19 years) from July 2006 to June 2008. HRV is known to be a useful tool for evaluating ANS activity, and we measured and compared HRV in the resting state. Results: The standard deviation of the N‐N interval (SDNN) and total power (TP) for patients with LUTS revealed no significant differences from those in the control group. On frequency domain analysis, there was evidence of decreased high frequency (HF) in patients with LUTS (P < 0.05), but there were no significant differences in other parameters, such as heart rate, square root of the mean squared differences of successive N‐N intervals (RMSSD), very low frequency (VLF), low frequency (LF), or LF/HF ratio. Conclusion: Patients with LUTS exhibited different HRV parameters compared with asymptomatic controls. Their decreased HF indicated that they may have had an imbalance in the autonomic nervous system.     

应用心率变异三角指数和平均心率评价心力衰竭患者心功能的研究

探讨心率变异 (HRV)三角指数和平均心率 (mHR)评价慢性心力衰竭 (简称心衰 )患者心功能状态的价值。应用动态心电图分析系统和彩色超声心动图对慢性心衰患者 (36例 )及健康对照组 (36例 )进行左室射血分数(LVEF)、左室舒张末内径 (LVd)、2 4hHRV三角指数和mHR等参数测量。结果 :①心衰组与对照组比较 ,mHR ,三角指数 ,LVd ,LVEF均有显著统计学差异 ,P <0 .0 1。②心衰组中三角指数和mHR与LVEF具有相关性 (r分别为- 0 .743,- 0 .6 35 ,P <0 .0 5及 0 .0 1)。③三角指数与mHR在心衰组中具有相关性 (r=0 .2 9,P =0 .0 0 8) ,在对照组中不具有相关性 (r=0 .33,P =0 .38)。结论 :在慢性心衰患者中 ,三角指数和mHR对于评价心衰患者心功能具有一定意义     

Heart Rate Variability in Patients with Congenital Long QT Syndrome

Background: The congenital long QT syndrome (LQTS) affecting myocardial repolarization is caused by mutations in different cardiac potassium or sodium channel genes. Adrenergic triggers are known to initiate life‐threatening torsade de pointes ventricular tachycardias in LQTS patients, and anti‐adrenergic therapy has been shown to be effective in many cases. Despite this well‐documented adrenergic component, the data about autonomic modulation of the heart rate in LQTS, as described by heart rate variability (HRV) analysis, are very limited. Methods: Conventional time‐ and frequency‐domain and newer nonlinear measures of HRV were compared in resting conditions among 27 LQTS patients with gene mutations at the LQT1 (n = 8), LQT2 (n = 10) or LQT3 (n = 9) loci and 34 LQTS noncarrier family members. Results: None of the conventional time‐ or frequency‐domain or newer nonlinear measures of HRV differed significantly between the LQTS carriers and LQTS noncarriers or between the LQT1, LQT2, and LQT3 carriers. Conclusions: These findings suggest that baseline cardiac autonomic modulation of the heart rate measured in resting conditions by traditional or newer nonlinear measures of HRV is not altered in LQTS patients. Furthermore, no differences are observed in HRV parameters between LQTS patients with potassium (KvLQT1, HERG), and sodium (SCN5A) ion channel gene mutations. HRV analysis in resting conditions does not improve phenotypic characterization of LQTS patients. A.N.E. 2001;6(4):298–304     

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.     

经皮球囊二尖瓣成形术对心率变异的影响

为了解经皮球囊二尖瓣成形术（ＰＢＭＶ）对风湿性心脏病二尖瓣狭窄病人心率变异（ＨＲＶ）的影响，自同期行ＰＢＭＶ的７１例病人中选择窦性心律者作为观察对象。于术前二日和术后第三日记录５ｍｉｎ的心搏数，经短时ＨＲＶ软件分析。结果表明术后ＲＲ间期均值标准差（３３．１８±１０．４２ｍｓｖｓ４２．８０±１５．８４ｍｓ，Ｐ＜０．０５）、相邻ＲＲ间期差值的均方根（２９．６１±１３．３８ｍｓｖｓ３７．５２±２６．０８ｍｓ，Ｐ＜０．０５）、相邻ＲＲ间期差值大于５０ｍｓ的百分比（６．７６±７．４９％ｖｓ９．０３±１０．２３％，Ｐ＜０．０１）、高频能谱（６１５．５８±４８５．６２ｂｐｍ２ｖｓ７０１．９７±６４９．９６ｂｐｍ２，Ｐ＜０．０５）均明显增大或升高。而平均心率（７４．３２±１１．３７ｂｐｍｖｓ６５．８８±７．７３ｂｐｍ，Ｐ＜０．０１）、最大心率（９５．６８±２８．６８ｂｐｍｖｓ７６．１４±８．５３ｂｐｍ，Ｐ＜０．０１）、低频能谱（４３８．２２±４０９．３１ｂｐｍ２ｖｓ２４０．１８±１９８．６８ｂｐｍ２，Ｐ＜０．０１）、极低频能谱（９７１．７４±５２９．５３ｂｐｍ２ｖｓ７２１．４３±５６４．０９ｂｐｍ２，Ｐ＜０．０１）均明显降?