Different Action of Beta‐blockers on Daytime and Nighttime Heart Rate Variability

Background: Beta‐blockers in patients surviving acute myocardial infarction (AMI) and in those with dilated cardiomyopathy have proven to be of beneficial effect, particularly for the sudden cardiac death rate. They are also used to control various forms of arrhythmias because of the strong correlation between cardiac arrhythmias and adrenergic reaction. Heart rate variability (HRV) variables provide valuable information related to the autonornic nervous system function. The present prospective study was undertaken to investigate the effects of beta‐blockers on 24‐hour HRV. Methods: We studied 60 patients, aged 39 to 76 years (mean 56 ± 15). Forty of the patients had survived a myocardial infarction 12 to 24 months previously (group I). Twenty patients did not have apparent cardiac heart disease (group II). Twenty‐four‐hour monitoring was performed at baseline and after 8 to 10 days of atenolol (100 mg/day, n = 35) or metoprolol (100 to 150 mg/day, n = 25) (BB). Measures of HRV in the time and frequency domains were calculated and printed for the the entire 24 hours and from 09:00 to 21:00 (daytime) and 23:00 to 6:00 (nighttime). The 24‐hour analysis of HRV shows an improvement over control values in indices of parasympathetic tone, but the results were statistically significant only for high frequency power (HF) in groups I (P < 0.01) and II (P < 0.05). A significant decrease of the coefficient of variance was noted in group II (P < 0.05). The analysis during the day and the night revealed a predominant action of beta‐blockers during the night with a high frequency increase in both groups from 64.5 ± 45 to 161 ± 111 ms² in group I (P < 0.001) and from 99 ± 89 to 268 ± 348 ms2 in group II (P < 0.02). In group II, the daily high frequency power did not vary after beta‐blockers. The decrease of the coefficient of variance in group II disappeared in the daily and nightly analysis Conclusions: Beta‐blockers enhance the HRV indexes reflecting the parasympathetic activity especially during the night in patients with and without ischemic heart disease. Although an indirect effect of beta‐blockers on respiration cannot be excluded, this effect could explain one of the beneficial effects of beta‐blockers on general survival in patients with and without myocardial infarction.     

Levosimendan versus dobutamine in heart failure patients treated chronically with carvedilol

Introduction : Although beta‐blockers are highly effective in the treatment of heart failure (HF), many patients with HF receiving a beta‐blocker continue to become decompensated and require hospitalization for worsening HF. Levosimendan and dobutamine are used to manage decompensated HF, but their comparative effects on left ventricular (LV) function in patients prescribed beta‐blockers are unknown. Aims : The aim of this study was to compare the effects of dobutamine and levosimendan on LV systolic and diastolic functions in chronic HF patients treated chronically with carvedilol. Forty patients with chronic HF who had NYHA class III to IV symptoms, a LV ejection fraction (LVEF) <40%, and ongoing treatment with carvedilol were enrolled in this randomized (1:1), dobutamine controlled, open‐label study. Before and 24 h after treatment, LVEF, mitral inflow peak E and A wave velocity, E/A ratio, the deceleration time of the E wave (DT), isovolumic relaxation time (IVRT), peak systolic (Sm) and early diastolic (Em) mitral annular velocity, and systolic pulmonary artery pressure (SPAP) were measured by echocardiography. Results : Levosimendan produced a statistically significant increase in LVEF (28 ± 5% vs. 33 ± 3%), Sm (6.5 ± 1.2 cm/s vs. 7.4 ± 0.9 cm/s), DT (120 ± 10 ms vs. 140 ± 15 ms), and Em (7.5 ± 0.4 cm/s vs. 8.1 ± 0.5 cm/s) and significant decrease in E/A ratio (2.1 ± 0.3 vs. 1.7 ± 0.4) and SPAP (55 ± 5 mmHg vs. 40 ± 7 mmHg). No significant change occurred in LV systolic and diastolic function parameters, or SPAP with dobutamine treatment. Levosimendan did not significantly alter the heart rate (72 ± 4 bpm vs. 70 ± 3 bpm), systolic (105 ± 5 mmHg vs. 102 ± 4 mmHg), or diastolic blood pressure (85 ± 5 mmHg vs. 83 ± 5 mmHg) whereas with dobutamine treatment, all these parameters significantly increased. Conclusions : Dobutamine and levosimendan have different effects on LV functions in patients treated chronically with carvedilol. These differences should be considered when selecting inotropic therapy for decompensated HF receiving long‐term carvedilol.     

Apnea‐Related Heart Rate Variability and Its Clinical Utility in Congestive Heart Failure Outpatients

Background: Cheyne‐Stokes breathing (CSB) is an abnormal cyclical pattern of respiratory fluctuations observed during sleep in congestive heart failure (CHF) of poor prognosis. We examined the clinical usefulness of CSB screening using the heart rate variability (HRV) data from the ambulatory electrocardiogram. Methods: We monitored ambulatory electrocardiograms and respiration simultaneously in 86 heart disease patients of both sexes, aged 57 ± 1 years. HRV was analyzed by the maximum entropy method during the sleeping period (11 PM—S AM). The 43 CHF patients underwent a 1‐year follow‐up study. Results: In the power spectra of the HRV, peaks were observed within the CSB band (0.005 to 0.03 Hz). Statistically significant differences in HRV were observed between CSB patients and CSB‐free patients in very low frequency (VLF) (P = 0.04), VLF/total frequency (TF) (P = 0.02), CSB (P = 0.01), CSB/TF (P = 0.003), and CSB/VLF (P < 0.0001). Cardiac events occurred in 23% of patients, including cardiac death in two, and rehospitalization for aggravated CHF in eight. In a multivariate Cox regression analysis in which age, sex, ejection fraction, NYHA functional class, beta blocker use, and basic heart disease were included, absence of ACE inhibitor use (RR 5.5, 95% Cl 1.0–31) and CSB/VLF ≧ 80% (RR 4.2, 95% Cl 1.1–17) remained significant predictors of cardiac events. Conclusions: HRV can act as an indicator of the presence of CSB in CHF patients, and could therefore be used, under outpatient conditions, to identify a CHF patients with a poor prognosis. A.N.E. 2002;7(2):127–132     

Cardiac Effects of Chronic Oral Beta‐Blockade:

Background: Although well established on the sinus node, the effects of beta‐blockade on ventricular repolarization are still conflicting. The aim of the study was to investigate the effects of a chronic beta‐blockade on sinus node and repolarization parameters and their relationship. Methods: Sixteen healthy volunteers (10 males, mean age: 40 ± 6.7 years) were randomized to placebo or atenolol (100 mg). After 7 days, subjects were crossed over. Heart rate (HR) and HRV indices were calculated from long‐term ECG recordings separately during the day and at night, together with ventricular repolarization parameters (QT interval duration and QT rate‐dependence). Results: Mean R‐R intervals were significantly and consistently increased after atenolol (Day: 916 ± 103 ms vs. 712 ± 89 ms, and Night: 1149 ± 93 vs. 996 ± 125 ms). HRV changes under atenolol were also consistent, with a significant decrease in sympathovagal ratio. In contrast, atenolol only lowered diurnal QT rate‐dependence (0.123 ± 0.032 vs. 0.190 ± 0.065 on placebo, P < 0.001), but not the nocturnal pattern. After multivariate analysis QT rate‐dependence changes induced by atenolol were correlated with pretreatment QT/RR relation (r = 0.65, P < 0.01) but not with any HR or HRV parameters. Conclusions: In healthy subjects, repolarization changes following chronic beta‐blockade cannot be predicted by HR or HRV changes, but are dependent on pretreatment rate‐dependence. A.N.E. 2002;7(4):379–388     

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.     

心得安改善短效钙拮抗剂心痛定心率变异性的研究

探讨β受体阻滞剂心得安是否可以改善短效钙拮抗剂心痛定的心率变异性(HRV)。将101例观察对象随机分为对照组(只使用心痛定,n=49)和试验组(使用心痛定和心得安,n=52),分别在服药前及服药后7～10天做24h动态心电图检测,分析HRV指标:正常RR间期的标准差(SDNN)、每5min平均RR间期的标准差(SDANN)、相邻RR之差的均方根(RMSSD)、相邻RR之差>50ms占总窦性心搏的百分数(PNN50)、低频(LF)、高频(HF)、低频和高频比值(LF/HF)。结果:对照组在治疗后心率(HR)加快,SDNN、SDANN显著降低(分别为105.2±31.8msvs126.9±32.0ms、98.9±20.1msvs107.9±19.8ms,P均<0.05),LF、LF/HF升高(分别229.3±77.1Hzvs196.1±64.8Hz、5.4±1.9vs3.8±1.8,P均<0.05),HRV降低;而试验组在治疗后心率无明显改变,SDNN、SDANN、LF、HF升高(分别为140.1±29.8msvs129.1±31.9ms、127.8±21.1msvs108.2±20.1ms、209.8±70.1Hzvs197.3±65.1Hz、148.5±48.8Hzvs123.5±41.0Hz,P均<0.05),LF/HF降低(P<0.05),治疗组HRV升高。结论:心得安能改善短效钙拮抗剂心痛定的HRV。     

Randomized Study of Early Intravenous Esmolol Versus Oral Beta‐Blockers in Preventing Post‐CABG Atrial Fibrillation in High Risk Patients Identified by Signal‐Averaged ECG: Results of a Pilot Study

Background: Patients with prolonged signal‐averaged ECG have four times higher risk for development of atrial fibrillation (AF) after coronary artery bypass surgery (CABG). Incidence of AF is reduced, but not eliminated by prophylaxis with beta‐blockers. The limitations of prophylaxis with oral beta‐blockers may be related to the delayed effect of oral therapy. We performed a pilot study of the efficacy of early intravenous esmolol and an oral beta‐blocker regimen for prevention of postoperative AF. Methods: Fifty patients referred for CABG and considered to be at high risk for postoperative AF on the basis of prolonged signal‐averaged ECG P wave duration > 140 ms were randomized to receive either a 24‐hour infusion of esmolol 6–18 hours after CABG, at an average dose 67 ± 7 μ/kg/min, followed by oral beta‐blockers versus oral beta‐blockers only beginning on postoperative day 1. Results: Seven of 27 patients (26%) in the esmolol group and 6 of 23 patients (26%) in the oral beta‐blocker group developed postoperative AF, P = NS. The mean time of onset of AF (2.7 ± 0.5 vs 2.7 ± 0.3 postoperative day, P = NS) and the median duration of AF (10 [2192] vs 7 [1.16] hours, P = NS) were similar between the two groups. Eleven (41%) patients treated with esmolol developed adverse events (hypotension: 8, bradycardia requiring temporary pacing: 2, left ventricular failure:1 patient) as compared to only one patient (4%) in the beta‐blocker group who developed hypotension, P = 0.006. Conclusions: This randomized controlled pilot study suggests that intravenous esmolol is less well tolerated and offers no advantages to standard beta‐blocker in preventing AF after CABG. A.N.E. 2002;7(2):86–91     

扩张性心肌病并心力衰竭患者双室同步起搏治疗对心率变异性的影响

观察双室同步起搏对扩张性心肌病并心力衰竭 (简称心衰 )患者心功能及心率变异性 (HRV)的影响。选择1 5例扩张性心肌病并顽固心衰患者 ,置入双室起搏器 ,观察心功能、HRV及血浆丙二醛、一氧化氮、内皮素 1、血管紧张素 Ⅱ的变化。结果 :心功能NYHA分级从术前 3.32± 0 .31级提高为 2 .1 8± 0 .33级 ,左室射血分数由 0 .2 9± 0 .0 3增至 0 .36± 0 .0 3(P <0 .0 5 ) ;2 4h正常RR间期均值标准差、相邻RR间期差值均方根、相邻RR间期差值 >5 0ms占正常RR间期数的百分比、总功率、低频及高频波段功率分别由 73± 8.1ms、4 1± 8.0ms2 、5 .3%± 1 .5 %、1 0 2 4± 4 1 3ms2 、1 1 5± 35ms2 及 4 8± 1 5ms2 增至 1 0 7± 1 3ms、70± 1 1ms2 、1 1 .3%± 3.4 %、1 92 1± 4 84ms2 、1 94± 35ms2 及 91± 2 9ms2 (P均 <0 .0 1 ) ;血浆丙二醛、内皮素 1分别由 4 31± 37nmol/L、83.1± 2 1ng/L降至 32 3± 2 9nmol/L、6 7.3± 1 6ng/L ,一氧化氮由 38.1± 7.6 μmol/L增至 5 1 .3± 9.2 μmol/L(P均 <0 .0 1 ) ,血管紧张素 Ⅱ无变化 (P >0 .0 5 )。结论 :同步起搏改善扩张性心肌病心衰患者心功能及HRV。     

严重充血性心力衰竭患者自主神经功能与心率变异的关系及地高辛的影响

对２５例重度充血性心力衰竭（ＣＨＦ）患者在地高辛治疗前后测定血浆去甲肾上腺素（ＮＥ）及心率变异（ＨＲＶ）。结果显示：ＮＥ基础值与ＨＲＶ时域指标基础水平均呈负相关（Ｐ＜０．０５或＜０．０１）。地高辛治疗前后的ＮＥ相比（２９１±８０ｐｇ／ｍｌｖｓ２１３±８２ｐｇ／ｍｌ），Ｐ＜０．００１。２４小时平均ＲＲ间期及２４小时正常ＲＲ间期标准差由治疗前的７２７±１２３ｍｓ及６７．７±２１．８ｍｓ分别增加至７７７±１２２ｍｓ及８７．２±２９．２ｍｓ（Ｐ均＜０．０５）；２４小时相邻ＲＲ间期差值的均方根（ＲＭＳＳＤ）、２４小时正常相邻ＲＲ间期之差大于５０ｍｓ的心搏数所占百分比（ＰＮＮ５０）及高频（ＨＦ）由治疗前的３６．３±３０．６ｍｓ、５．３±５．５％及３７．１±２１．２ｍｓ２分别增加至５６．１±４３．７ｍｓ、１０．８±１０．６％及７９．９±５８．２ｍｓ２（Ｐ值＜０．０５至＜０．０１）；低频（ＬＦ）由治疗前的１１８．９±１３３．２ｍｓ２增加至１７１．２±１７２．８ｍｓ２（Ｐ＜０．００５）；ＮＥ下降幅度与时域指标增加幅度均呈正相关。ＨＲＶ多数时域指标增加幅度及其绝对值与血清地高辛浓度呈正相关，以ＲＭＳＳＤ和ＰＮＮ５０尤为显著（Ｐ?     

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.     

Effects of Carvedilol on Heart Rate Dynamics in Patients with Congestive Heart Failure

Background: Patients with congestive heart failure (CHF) have alterations in the traditional and nonlinear indices of heart rate (HR) dynamics, which have been associated with an increased risk of mortality. This study was designed to test the effects of carvedilol, a nonselective beta‐blocker with alpha‐1 blocking properties, on HR dynamics in patients with CHF. Methods: We studied 15 patients with CHF secondary to ischemic or idiopathic cardiomyopathy who met the following inclusion criteria: NYHA functional class II‐III, optimal conventional medical therapy, normal sinus rhythm, left ventricular ejection fraction (LVEF) of < 40%, and resting systolic blood pressure greater than 100 mmHg. The 6‐minute corridor walk test, estimation of LVEF, and 24‐hour Holter recording were performed at baseline and after 12 weeks of therapy with carvedilol. Traditional time and frequency domain measures and short‐term fractal scaling exponent of HR dynamics were analyzed. Results: After 12 weeks of therapy with carvedilol, the mean LVEF improved significantly (from 0.27 ± 0.08 to 0.38 ± 0.08, P < 0.001). The average HR decreased significantly (from 86 ± 11 to 70 ± 8 beats/min, P < 0.001). The mean distance traveled in the 6‐minute walk test increased significantly (from 177 ± 44 to 273 ± 55 m, P < 0.01). The frequency‐domain indices (HF and LF), the time domain indices (rMSSD and PNN5), and the short‐term fractal scaling exponent increased significantly. The scaling exponent increased particularly among the patients with the lowest initial values (< 1.0), and the change in the fractal scaling exponent correlated with the change in ejection fraction (r = 0.63, P < 0.01). Conclusion: Carvedilol improves time and frequency domain indices of HR variability and corrects the altered scaling properties of HR dynamics in patients with CHF. It also improves LVEF and functional capacity. These specific changes in HR behavior caused by carvedilol treatment may reflect the normalization of impaired cardiovascular neural regulation of patients with CHF. A.N.E. 2002;7(2):133–138     

Impact of Left Ventricular Remodeling on Ventricular Repolarization and Heart Rate Variability in Patients after Myocardial Infarction Treated with Primary PCI: Prospective 6 Months Follow‐up

Background: The relation between postinfarction left ventricle remodeling (LVR), autonomic nervous system and repolarization process is unclear. Purpose of the study was to assess the influence of LVR on the early (QTpeak) and late (TpeakTend) repolarization periods in patients after myocardial infarction (MI) treated with primary PCI. The day‐to‐night differences of repolarization parameters and the relation between QT and heart rate variability (HRV) indices, as well left ventricle function were also assessed. Methods: The study cohort of 104 pts was examined 6 months after acute MI. HRV and QT indices (corrected to the heart rate) were obtained from the entire 24‐hour Holter recording, daytime and nighttime periods. Results: LVR was found in 33 patients (31.7%). The study groups (LVR+ vs LVR?) did not differ in age, the extent of coronary artery lesions and treatment. Left ventricle ejection fraction (LVEF) was lower (38%± 11% vs 55%± 11%, P < 0.001), both QTc (443 ± 26 ms vs 420 ± 20 ms, P < 0.001) and TpeakTendc (98 ± 11 ms vs 84 ± 12 ms, P < 0.005) were longer in LVR + patients, with no differences for QTpeakc. Trends toward lower values of time‐domain (SDRR, rMSSD) HRV parameters were found in LVR+ pts. Day‐to‐night difference was observed only for SDRR, more marked in LVR‐group. Remarkable relations between delta LVEF (6 months minus baseline), delta LVEDV and TpeakTendc were found, with no such relationships for QTpeakc. Conclusions: The patients with LVR have longer repolarization time, especially the late phase‐ TpeakTend, which represents transmural dispersion of repolarization. Its prolongation seems to be related to local attributes of myocardium and global function of the left ventricle but unrelated to the autonomic nervous influences. Remodeling with moderate LV systolic dysfunction is associated with insignificant decrease in HRV indices and preserved circadian variability.     

Heart Rate Turbulence for Prediction of Heart Transplantation and Mortality in Chronic Heart Failure

Background: Previous studies have shown conflicting results about the value of heart rate turbulence (HRT) for risk stratification of patients (pts) with chronic heart failure (CHF). We prospectively evaluated the relation between HRT and progression toward end‐stage heart failure or all‐cause mortality in patients with CHF. Methods: HRT was assessed from 24‐hour Holter recordings in 110 pts with CHF (54 in NYHA class II, 56 in class III–IV; left ventricular ejection fraction (LVEF) 30%± 10%) on optimal pharmacotherapy and quantified as turbulence onset (TO,%), turbulence slope (TS, ms/RR interval), and turbulence timing (beginning of RR sequence for calculation of TS, TT). TO ≥ 0%, TS ≤ 2.5 ms/RR, and TT >10 were considered abnormal. End point was development of end‐stage CHF requiring heart transplantation (OHT) or all‐cause mortality. Results: During a follow‐up of 5.8 ± 1.3 years, 24 pts died and 10 required OHT. TO, TS, TT, and both (TO and TS) were abnormal in 35%, 50%, 30%, and 25% of all patients, respectively. Patients with at least one relatively preserved HRT parameter (TO, TS, or TT) (n = 98) had 5‐year event‐free rate of 83% compared to 33% of those in whom all three parameters were abnormal (n = 12). In multivariate Cox regression analysis, the most powerful predictor of end point events was heart rate variability (SDNN < 70 ms, hazard ratio (HR) 9.41, P < 0.001), followed by LVEF ≤ 35% (HR 6.23), TT ≥ 10 (HR 3.14), and TO ≥ 0 (HR 2.54, P < 0.05). Conclusion : In patients with CHF on optimal pharmacotherapy, HRT can help to predict those at risk for progression toward OHT or death of all causes. Ann Noninvasive Electrocardiol 2010;15(3):230–237     

Effects of Left and Right Pneumonectomy on Time- and Frequency-Domain Parameters of Heart Rate Variability

Background: Morbid cardiac events after pneumonectomy have been attributed to autonornic mechanisms. Analysis of heart rate variability (HRV) offers a noninvasive technique to assess modulation of sympathetic and parasympathetic activity. There is little data available on the systematic changes in time- and frequency-domain parameters of HRV in response to pneumonectomy and cardiac plexus neural trauma. Methods: We measured HRV parameters in 54 patients undergoing left (n = 28) and right (n = 26) pneumonectomy (age 55 ± 11 years) who were without congestive heart failure, active ischemic heart disease, or dysrhythmias, and were not taking β-blocker or calcium channel blocker therapy. Time- and frequency-domain indices of HRV were measured before surgery (1 hour) and continuously after surgery (Holter) for 3 days. HRV indices measured were: mean R-R interval (ms), mean of all 5-minute standard deviation of R-Rs (SDSD; ms); root mean square of difference of successive R-Rs (rMSSD; ms); proportion of adjacent R-Rs > 50 ms different (pNN50;%); total (TF; 0.01–1.00 Hz), low (LF; 0.04 - 0.15 Hz) and high frequency (HF; 0.15–0.40 Hz) power (ms²). Results: Time (R-R, SDSD, rMSSD, pNN50 and frequency (TF, LF, HF, LF/HF) indices of HRV decreased significantly in response to left or right pneumonectomy. The maximal decrease in HRV occurred during the first 24 to 48 hours. There were no differences between the groups in any measured HRV parameter. Mean heart rate ranged between 80 to 110 beats/min postoperatively for all patients. Conclusions: Decrements in time- and frequency-domain indices of HRV occurred after pneumonectomy independently of the operative side. Global reductions in HRV after surgery support the presence of parasympathetic withdrawal. Although global changes in HRV may reflect an individual's response to surgical stress, the usefulness of HRV to study fine changes in physiological control mechanisms in the postoperative state appears limited. A.N.E. 1999;4(3):325–332     

Association of the Heart Rate Turbulence with Classic Risk Stratification Parameters in Postmyocardial Infarction Patients

The heart rate turbulence (HRT) parameters were introduced for risk stratification of ventricular arrhythmias in postmyocardial infarction patients. However, the relationship of these parameters with other risk stratificators such as heart rate variability (HRV), repolarization parameters or left ventricular function is unknown. Furthermore, the influence of age and medication on HRT remains to be evaluated. Holter ECG's of 509 post‐MI patients (1–10 years after MI) were screened for single ventricular extrasystole. In 196 patients the parameters' turbulence onset (TO) and turbulence slope (TS) could be computed. A pathological TO (>0%) and TS (<2.5 ms) was found in 58 and 54 patients, respectively. HRT was not related to gender, but was correlated with age (TS: r = 0.209, P < 0.01) . No relationship was observed between QT interval, QTc interval or QT dispersion and HRT parameters. Individuals with a pathological HRT showed decreased HRV values (e.g., PNN50: 2.8 vs. 11.5; P < 0.001 ). Of all MI patients with systolic left ventricular dysfunction (EF < 45%, n = 46) , 18 showed a pathological TO (39%) compared to 34 out of 142 patients (24%) with an EF > 45%. In contrast, the percentage of pathological HRT was not different between patients with left ventricular hypertrophy (16 out of 59, 27%) compared to patients without LVH (38 out of 133, 28%). The HRT was pathological in 14 out of 24 patients with diabetes mellitus (58%) compared to 40 out of 172 (23%) normoglycemic patients (TO: ?0.6 ± 3.1 vs. ?2.5 ± 5.5, P < 0.02 ). HRT was similar in patients with ß‐blockers (n = 96) as in patients without ß‐blockers (n = 100) . In stable post‐MI patients, HRT is influenced by age and left ventricular function and correlates with heart rate variability. Therapy with ß‐blockers has no influence on HRT, while diabetic patients may have an increased likelihood of pathological HRT.     

Abnormalities of Ventricular Repolarization in Mitral Valve Prolapse

Objectives: Mitral valve prolapse (MVP) is associated with arrhythmias and sudden death. Some studies suggest that abnormalities of the autonomic nervous system (ANS) may contribute to these arrhythmias. In a family investigation with genetic analysis of patients carrying a MVP, we performed a Holter study to define the autonomic profile of MVP. Methods and Results: A 24‐hour digitized 3‐lead Holter ECG was recorded in 30 patients with MVP and in two control groups, a group of 30 healthy relatives and a group of 31 healthy volunteers. We studied especially heart rate variability (HRV) and QT dynamicity. The slope of the relationship between ventricular repolarization and heart rate was studied separately during day and night. There was no difference in HRV (SDNN, rMSSD) among the three groups. On the contrary, QT interval duration was increased in patients with MVP as compared to healthy relatives (QT end: 409 ± 52 ms vs 372 ± 23 ms, P < 0.05; QT apex: 319 ± 42 ms vs 286 ± 23 ms, P < 0.01) and to healthy volunteers (QT end: 409 ± 52 ms vs 376 ± 25 ms, P = 0.004; QT apex: 319 ± 42 ms vs 289 ± 23 ms, P < 0.01). Nocturnal ventricular repolarization rate dependence was increased in MVP as compared to healthy relatives (0.16 ± 0.06 vs 0.13 ± 0.04, P < 0.05) and to healthy volunteers (0.16 ± 0.06 vs 0.11 ± 0.06, P < 0.001) whereas the 24‐hour and diurnal QT–R‐R slope was not disturbed. Conclusion: In MVP, QT is increased and the circadian modulation of QT end/RR slope is disturbed with an increased nocturnal rate dependence. These abnormalities of ventricular repolarization might explain the risk of arrhythmic events in MVP.     

Heart Rate Variability Fraction—A New Reportable Measure of 24‐Hour R‐R Interval Variation

Background: The scatterplot of R‐R intervals has several unique features. Its numerical evaluation may produce a new useful index of global heart rate variability (HRV) from Holter recordings. Methods: Two‐hundred and ten middle‐aged healthy subjects were enrolled in this study. The study was repeated the next day in 165 subjects. Each subject had a 24‐hour ECG recording taken. Preprocessed data were transferred into a personal computer and the standard HRV time‐domain indices: standard deviation of total normal R‐R intervals (SDNN), standard deviation of averaged means of normal R‐R intervals over 5‐minute periods (SDANN), triangular index (TI), and pNN50 were determined. The scatterplot area (0.2–1.8 second) was divided into 256 boxes, each of 0.1‐second interval, and the number of paired R‐R intervals was counted. The heart rate variability fraction (HRVF) was calculated as the two highest counts divided by the number of total beats differing from the consecutive beat by <50 ms. The HRVF was obtained by subtracting this fraction from 1, and converting the result to a percentage. Results: The normal value of the HRVF was 52.7 ± 8.6%. The 2–98% range calculated from the normal probability plot was 35.1–70.3%. The HRVF varied significantly with gender (female 48.7 ± 8.4% vs male 53.6 ± 8.6%, P = 0.002). The HRVF correlated with RRI (r = 0.525) and showed a similar or better relationship with SDNN (0.851), SDANN (0.653), and TI (0.845) than did the standard HRV measures with each other. Bland‐Altman plot showed a good day‐by‐day reproducibility of the HRVF, with the intraclass correlation coefficient of 0.839 and a low relative standard error difference (1.8%). Conclusion: We introduced a new index of HRV, which is easy for computation, robust, reproducible, easy to understand, and may overcome the limitations that belong to the standard HRV measures. This index, named HRV fraction, by combining magnitude, distribution, and heart‐rate influences, might become a clinically useful index of global HRV.     

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?     

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.     

Apnea‐Related Heart Rate Variability in Congestive Heart Failure Patients

Sleep‐disordered breathing (SDB) causes fluctuation of the RR interval. However, the details are uncertain. We studied the characteristics of sleep‐related heart rate variation (HRV) in congestive heart failure (CHF) patients with SDB. Ambulatory electrocardiograms and data on respiration (oronasal flow, trachea sound, abdominal wall movement, and oxygen saturation) were simultaneously recorded by a multi‐channel digital recorder for 13 CHF patients (8 men and 5 women; mean age, 68 ± 4 years). Heart rate variation occurred as a result of cyclical apnea attacks between 0.005 and 0.03 Hz (apnea band). The proportion of the apnea band (% apnea) increased with the number of apnea episodes, and SDB was highly likely when the % apnea was ≥80%. Low‐flow oxygen administration effectively reduced apnea frequency, and the apnea‐related HRV also decreased. We concluded that apnea‐related HRV was useful for detecting and following SDB in CHF cases.