bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wavelet Analysis of Signal‐Averaged Electrocardiograms
Authors: Malik Marek , Hnatkova Katerina , Staunton Anne , Camm A. John 
Published: October 2006

Background:Spectral techniques for the analysis of signal‐averaged electrocardiogram (ECG) are superior to the standard time‐domain analysis in special circumstances but none of these techniques is better than the time‐domain analysis in the prospective risk stratification of survivors of myocardial infarction (Ml). Aim:This study applied wavelet decomposition of signal‐averaged ECGs to prospective risk stratification of Ml survivors and compared its performance with that of conventional time‐domain analysis. Methods:Eligible patients were aged 75 years without atrial fibrillation, important noncardiac disease, bundle branch block, ventricular preexcitation, permanent pacemaker, or a history of cardiac surgery. Of 754 eligible patients, signal‐averaged ECG recordings were available in 551. During a 2‐year follow‐up, 32 patients suffered from cardiac death (CM), 21 potentially arrhythmic death, 19 sudden cardiac death (SCO), 19 developed nonfatal sustained ventricular tachycardia (VT), and 5 were resuscitated from an ECG‐documented ventricular fibrillation. Signal‐averaged ECG indices from both analyses were compared in patients with and without different follow‐up events. The positive predictive characteristics (dependency of positive predictive accuracy on sensitivity) for predicting different follow‐up events based on both modes of analysis were compared at selected levels of sensitivity. Results: Time‐domain signal‐averaged ECGs were strongly correlated with incidence of VT (P = 0.01). Positive wavelet analysis was more strongly correlated with this event (P < 0.005) and with cardiac mortality (P < 0.05). For all events, wavelet analysis gave higher positive predictive accuracy (PPA) than the time‐domain analysis, e.g., the prediction of SCD at sensitivity of 25%, wavelet and time‐domain analyses gave PPA of 20.0% and 6.5%, respectively (P < 10‐10). Conclusion:Wavelet decomposition analysis of signal‐averaged ECGs is superior to the standard time‐domain analysis in predicting post‐MI events. In particular, this analysis identifies not only those post‐MI patients who are at high risk of nonfatal sustained VT but also those who are at risk of SCD. A.N.E. 2000;5(1):20–29
Autonomic Nerve Tone After an Eastward Transmeridian Flight as Indicated by Heart Rate Variability
Authors: Tateishi Osamu , Nogimura Takeshi , Honda Youichi , Goto Yutaka , Chin Keiichi , Itou Tetsushi , Mochizuki Seibu , Fujishiro Kentarou 
Published: October 2006

Background:Transmeridian flights commonly cause the physical distress and somnolence known as jet lag. Because the influence of jet lag on autonomic nerve tone (ANTi is unclear, we studied its influence by evaluating heart rate variability before versus after a flight from Tokyo to San Francisco. Methods:We recorded the ambulatory electrocardiograms of 12 healthy young men for 11 days, i.e., 3 days in Tokyo before the flight and 8 days in San Francisco following the flight. Heart rate variability was determined by power spectrum analysis. After calculating high frequency power (0.15–0.4 Hz, HF), low frequency power (0.04–0.15 Hz, LF), and LF/HF, we evaluated autonomic nerve tone using HF and LF/HF as indices of the activity of sympathetic and parasympathetic tone, respectively. In addition, we analyzed the circadian rhythm of autonomic nerve tone by the maximum entropy method. Results:Parasympathetic nerve tone was found to increase during the flight. The time required for the ANT to return to preflight levels differed between the waking and sleeping periods, being 5 and 7 days, respectively. Conclusions: ANT varied for 1 week after an eastward transmeridian flight. A.N.E. 2000;5(1):53–59
Utility of an Accelerometer Sensor Integrated into a Holter Monitoring System
Authors: Fotuhi Parwis , Combs William , Sheldon Todd , Theres Heinz , Stangi Karl , Baumann Gert 
Published: October 2006

Background:Patients routinely undergo Holter monitor evaluation for the detection of cardiac arrhythmias. Documentation of daily patient activities is a common shortcoming. Discriminating physiological from pathological heart rate, e.g., sinus tachycardia in response to exercise from supraventricular tachyarrhythmia, can be difficult without an accurate diary. Independent documentation of body activity may help solve this inadequacy. Accelerometer‐based pacing systems have established the utility of general body activity detection for pacemaker rate determination. Methods:An accelerometer sensor was positioned in the left pectoral region in 10 volunteers for measurement of normal daily subject activity. Additionally, the volunteers were asked to keep a detailed diary of daily activities. The accelerometer sensor signal was recorded on one channel of a modified Holter monitor system. The Holter FCG and accelerometer data were analyzed and compared to the detailed diary. The study was then repeated in 10 patients undergoing standard Holter monitor evaluation. Results:In all 20 subjects, reviewing the 24‐hour profiles allowed correlation of heart rate response to activities such as walking, resting, exercise, or sleep and the accelerometer sensor signal. In the patients, a total of 170 minutes of increased heart rate correlated with documented physical activity, while 14 minutes did not. Additionally, 161 minutes of bradycardia during physical activity were also identified. Conclusion:Present‐day Holter systems can detect bradycardias and tachycardias based on ECG characteristics and rate criteria. The addition of acceterometer signal to standard Holter ECG might improve physician interpretation of patient heart rate response to daily patient activities. A.N.E. 2000;5(1):73–78
Diagnostic Value of Exercise‐Induced ST‐Segment Elevation in Q‐Wave Leads. After Recent Myocardial Infarction
Authors: Zielinska Marzenna , Koniarek Wlodzimierz , Bolinska Halina , Maciejewski Marek 
Published: October 2006

Background: Exercise‐induced ST‐segment elevation in an infarct territory with abnormal Q waves is a known marker for more severe left ventricular wall‐motion abnormalities. However, it is reported, that exercise‐induced ST‐segment elevation in infarct leads may indicate residual viability in the intarctregion. The aim of the study was to test whether exercise‐induced ST‐segment elevation is related to left ventricular (LV) dysfunction or to persistent viability in patients with previous myocardial infarction (MI).Methods: 145 consecutive patients (119 men, 26 women, age 58 ± 11 years) 2–3 weeks after Q‐wave Ml but without ST elevation at rest ECG were enrolled in the study. All patients underwent a target heart rate or symptom‐limited exercise testing (ET) with Bruce protocol. Exercise‐induced ST‐segment elevation < 1 mm above the baseline ST segment level (80 ms after J point) in more than 1 ECG lead with Q wave was considered to be significant. Patients were divided in two groups according to ET results: group I, 25 patients with significant exercise‐induced ST‐segment elevation and group II, 120 patients without exercise‐induced ST‐segment elevation. All patients underwent rest ECHO and low dose dobutamine stress echo (LOSE) within 7 days after ET. LV function was estimated using ejection fraction (EF).Results: More severe LV dysfunction was observed in patients from group 1 (EF 31 ± 8.16% vs EF 45 ± 10.3%). Myocardial viability (defined as an improvement of regional systolic wall thickening in the regions with resting regional wall‐motion abnormalities during LOSE 5 to 15 g/kg/min was recognized in 8 patients (32%) in group I and 31 patients (25.8%) in group II. There was no relation between exercise‐induced ST‐segment elevation and myocardial viability (chi‐square test: 2,809; NS).Conclusions: Exercise‐induced ST‐segment elevation in most cases is associated with left ventricular dysfunction. Patients with exercise‐induced ST‐segment elevation have a lower EF than those without and greater severity of resting wall‐motion abnormalities. Our results suggest that exercise‐induced ST‐segment elevation is not related to residual myocardial viability.
Exercise QT Dispersion as an Independent Predictor of the Presence of Ischemia on Myocardial Perfusion Imaging
Authors: Morise Anthony P. , Beto Robert , Gupta Naresh , Gunel Erdogan 
Published: October 2006

Background: Increased QT dispersion on resting electrocardiography has been shown to be related to ischemia and to predict adverse cardiac events. The purpose of the present study was to evaluate the relationship between myocardial ischemia and the exercise QT dispersion response.Methods: We studied 368 patients with normal resting electrocardiograms referred for exercise SPECT myocardial perfusion scintigraphy because of suspected coronary disease. We used signal‐averaged recordings of 12‐lead electrocardiograms to manually measure QT dispersion at rest and peak exercise. We interpreted scintigrams visually as ischemic or nonischemic.Results: The 49 patients with scintigraphic ischemia were compared to the 319 patients without ischemia. Resting QT dispersion did not differ, but exercise QT dispersion was significantly greater in those with ischemia (25 ± 13 ms vs 32 ± 15 ms; P = 0.0004). Using logistic regression analysis with any ischemia present or absent as the dependent variable, exercise QT dispersion was an independent predictor (P = 0.0006) of the presence of ischemia. We also found a significant increase in receiver operating characteristic curve area when exercise QT dispersion was included in the model (areas 0.74 ± 0.04 vs 0.78 ± 0.03; P = 0.035). Exercise QT dispersion as a dependent variable was independently associated with sex (increased in women) and perfusion ischemia (positive relation).Conclusion: Exercise QT dispersion is an independent predictor of the presence of scintigraphic ischemia that has incremental value over other clinical and exercise test variables.
Ectopic Beats in Heart Rate Variability Analysis: Effects of Editing on Time and Frequency Domain Measures
Authors: Salo Mirja A. , Huikuri Heikki V. , Seppanen Tapio 
Published: October 2006

Background: Various methods can be used to edit biological and technical artefacts in heart rate variability (HRV), but there is relatively little information on the effects of such editing methods on HRV.Methods: The effects of editing on HRV analysis were studied using R‐R interval data of 10 healthy subjects and 10 patients with a previous myocardial infarction (Ml). R‐R interval tachograms of verified sinus beats were analyzed from short‐term (∼5 min) and long‐term (—24 hours) recordings by eliminating different amounts of real R‐R intervals. Three editing methods were applied to these segments: (1) interpolation of degree zero, (2) interpolation of degree one, and (3) deletion without replacement.Results: In time domain analysis of short‐term data, the standard deviation of normal‐to‐normal intervals (SDANN) was least affected by editing, and 30%‐50% of the data could be edited by all the three methods without a significant error (< 5%). In the frequency domain analysis, the method of editing resulted in remarkably different changes and errors for both the high‐frequency (HF) and the low‐frequency (LF) spectral components. The editing methods also yielded in different results in healthy subjects and AMI patients. In 24‐hour HRV analysis, up to 50% could be edited by all methods without an error larger than 5% in the analysis of the standard deviation of normal to normal intervals (SDNN). Both interpolation methods also performed well in the editing of the long‐term power spectral components for 24‐hour data, but with the deletion method, only 5% of the data could be edited without a significant error.Conclusions: The amount and type of editing R‐R interval data have remarkably different effects on various HRV indices. There is no universal method for editing ectopic beats that could be used in both the time‐domain and the frequency‐domain analysis of HRV. A.N.E. 2001;6(1):5–17
Reproducibility of QT Parameters Derived from 24‐hour Ambulatory ECG Recordings in Healthy Subjects
Authors: Arildsen Hanne , Christiansen Evald Høj , Pedersen Anders Kirstein , Møgaard Henning 
Published: October 2006

Aim: To estimate the reproducibility of QT parameters derived from 24‐hour ambulatory ECG recordings.Method: Ten healthy volunteers aged 25 to 41 years participated. In two 24‐hour ambulatory ECG recordings obtained 1 day apart, the QT interval was measured manually at stable heart rates in approximately 16 periods during daytime and 6 periods during nighttime. The association between the QT and RR interval was described by linear regression for day and nighttime separately and the following QT parameters were calculated: the QT interval at heart rate 60 beats/min during daytime (QT(60)day), slope(day), slope(night), and the difference in QT(60) between day and nighttime (ΔQT(60)). The QT parameters were assessed four times for each participant to discriminate method inaccuracy from day to day variation. The reproducibility was estimated as the coefficient of repeatability, the relative error, and the ratio between within‐subject variability and between‐subject variability.Results: The coefficient of repeatability, the relative error and the ratio, respectively, were 19 ms, 1.8% and 0.5 for QT(60)day, 0.076, 21% and 0.68 for slope(day), 0.116, 43% and 1.37 for slope(night), and 37 ms, 325% and 1.19 for ΔQT(60) when estimating the overall day to day reproducibility. Inaccuracy of QT measurement accounted for approximately 40% of this variation, whereas the error caused by selecting segments was small.Conclusion: QT(60)day has a high reproducibility and may with advantage replace the conventional QT interval measured on a resting ECG. To assess QT dynamics, the slope of the regression line during daytime is suitable and the short term reproducibility acceptable for clinical trials. Regarding slope(night) and ΔQT(60), the variation is high and the parameters should be used with caution. A.N.E. 2001;6(1):24–31
Computerized ST Depression Analysis Improves Prediction of All‐Cause and Cardiovascular Mortality: The Strong Heart Study
Authors: Okin Peter M. , Devereux Richard B. , Kors Jan A. , van Herpen Gerard , Crow Richard S. , Fabsitz Richard R. , Howard Barbara V. 
Published: October 2006

Background:Nonspecific ST depression assessed by standard visual Minnesota coding (MC) has been demonstrated to predict risk. Although computer analysis has been applied to digital ECGs for MC, the prognostic value of computerized MC and computerized ST depression analyses have not been examined in relation to standard visual MC.Methods:The predictive value of nonspecific ST depression as determined by visual and computerized MC codes 4.2 or 4.3 was compared with computer‐measured ST depression ≧ 50 μV in 2,127 American Indian participants in the first Strong Heart Study examination. Computerized MC and ST depression were determined using separate computerized‐ECG analysis programs and visual MC was performed by an experienced ECG core laboratory.Results:The prevalence of MC 4.2 or 4.3 by computer was higher than by visual analysis (6.4 vs 4.4%, P < 0.001). After mean follow‐up of 3.7 ± 0.9 years, there were 73 cardiovascular deaths and 227 deaths from all causes. In univariate Cox analyses, visual MC (relative risk [RR] 4.8,95% confidence interval [CIJ 2.6–9.1), computerized MC (RR 6.0, 95% Cl 3.5–10.3), and computer‐measured ST depression (RR 7.6, 95% CI 4.5–12.9) were all significant predictors of cardiovascular death. In separate multivariate Cox regression analyses that included age, sex, diabetes, HDL and LDL cholesterol, body mass index, systolic and diastolic blood pressure, microalbuminuria, smoking, and the presence of coronary heart disease, computerized MC (RR 3.0, 95% Cl 1.6–5.6) and computer‐measured ST depression (RR 3.1, 95% Cl 1.7–5.7), but not visual MC, remained significant predictors of cardiovascular mortality. When both computerized MC and computer‐measured ST depression were entered into the multivariate Cox regression, each variable provided independent risk stratification (RR 2.1, 95% Cl 1.0–4.4, and RR 2.1, 95% CI 1.0–4.4, respectively). Similarly, computerized MC and computer‐measured ST depression, but not visual MC, were independent predictors of all‐cause mortality after controlling for standard risk factors.Conclusions:Computer analysis of the ECG, using computerized MC and computer‐measured ST depression, provides independent and additive risk stratification for cardiovascular and all‐cause mortality, and improves risk stratification compared with visual MC. These findings support the use of routine computer analysis of ST depression on the rest ECG for assessment of risk and suggest that computerized MC can replace visual MC for this purpose. A.N.E. 2001;6(2):107–116
Improving the Reproducibility of QT Dispersion Measures
Authors: Lund Kaspar , Perkiömäki Juha S. , Brohet Christian , Zaïdi Mohammed , Elming Hanne , Pedersen Christian Torp , Huikuri Heikki V. , Nygaard Hans , Pedersen Anders Kirstein 
Published: October 2006

Background: The low reproducibility of the QT dispersion (QTD) method is a major reason why it is not used in clinics. The purpose of this study was to develop QT dispersion parameters with better reproducibility and identification of patients with a high risk of ventricular arrhythmia or death.Methods and Results: Three institutions using different methods for measuring QT intervals provided QT databases, which included more than 3500 twelve‐lead surface ECGs. The data represented low and high risk subjects from the following groups: the normal population EpiSet (survivors vs dead from cardiovascular causes), acute myocardial infarction patients AmiSet (survivors vs dead) and remote myocardial infarction patients ArrSet (with vs without a history of ventricular arrhythmia). The EpiSet, AmiSet, and the ArrSet contributed with N = 122, 0, and 110 ECGs for reproducibility analysis, and 3244, 446, and 100 ECGs for the analysis of prognostic accuracy. The prognostic accuracy was measured as the area under the Receiver Operator Curve. The QT intervals were divided into six QT pairs; the longest pair consisted of the longest and the shortest QT intervals etc. The QT dispersion trend (QTDT) was defined as the slope of the linear regression of the N longest QT pairs after estimation of missing QT intervals by interpolation of measured QT intervals. The QTMAD and the QTSTD methods were defined as twice the mean absolute deviation and the standard deviation of the N longest QT pairs. The reproducibility was improved by 27% and 19% in the EpiSet and the ArrSet relative to the reproducibility of QTD. The accuracy improved for the EpiSet and the ArrSet and was maintained for the AmiSet.Conclusions: By using the three longest and the three shortest QT intervals in QTDT, QTMAD, or QTSTD, the reproducibility improved significantly while maintaining or improving the prognostic accuracy compared to QTD. A.N.E. 2001;6(2):143–152
Normalization of Ventricular Repolarization with Flecainide in Long QT Syndrome Patients with SCN5A:ΔKPQ Mutation
Authors: Windle John R. , Geletka Robin C. , Moss Arthur J. , Zareba Wojciech , Atkins Dianne L. 
Published: October 2006

Background:The Long QT Syndrome (LQTS) is a genetic channelopathy with life‐threatening implications. The LQT3 form of this disease is caused by mutations of the SCN5A sodium‐channel gene. A specific mutation, SCN5A:ΔKPQ, is associated with repetitive reopenings of the sodium channel and prolonged inward current. This dominant inward current is manifest on the electrocardiogram as QT prolongation. Flecainide is a potent blocker of the open sodium channel.Methods and Results:The effect of flecainide on the duration of the QT‐interval and the T‐wave morphology was systematically evaluated in five male patients age 2–64 years having the SCN5A:ΔKPQ mutation. After baseline electrocardiograms were obtained, low‐dose oral flecainide was administered for 48 hours. Serial electrocardiograms and blood flecainide levels were obtained during flecainide therapy. The QTc interval decreased on average by 104 ms, from a baseline value of 565 ± 60 ms to 461 ± 23 ms (P < 0.04) at a mean flecainide level of 0.28 ± 0.08 mg/L, with shortening of the QTonset interval (P < 0.003) and normalization of T‐wave morphology. The effects of flecainide were compared with oral mexiletine in two patients, with flecainide showing greater QTc shortening and more complete normalization of repolarization. No adverse side effects or proarrhythmia were observed with flecainide in this study.Conclusion:Low‐dose, oral flecainide consistently shortened the QTc interval and normalized the repolarization T‐wave pattern in five LQT3 patients with SCN5A:ΔKPQ mutation. This preliminary study indicates that low‐dose flecainide is a promising therapeutic agent for LQTS patients with the SCN5A:ΔKPQ sodium channel mutation. A.N.E. 2001;6(2):153–158
QT Dispersion and Mortality in the Elderly
Authors: Perkiömäki Juha S. , Sourander Leif B. , Levomäki Lasse , Räihä Ismo J. , Puukka Pauli , Heikki V. Huikuri M.D., F.A.C.C.  
Published: October 2006

Background: The prognostic value of QT interval dispersion measured from a standard 12‐lead electrocardiogram (ECG) in the general population is not well established. The purpose of the present study was primarily to assess the value of QT interval dispersion obtained from 12‐lead ECG in the prediction of total, cardiac, stroke, and cancer mortality in the elderly.Methods: A random population sample of community‐living elderly people (n = 330, age ≧; 65 years, mean 74 ±; 6 years) underwent a comprehensive clinical evaluation, laboratory tests, and 12‐lead ECG recordings.Results: By the end of the 10‐year follow‐up, 180 subjects (55%) had died and 150 (45%) were still alive. Heart rate corrected QT (QTc) dispersion had been longer in those who had died than in the survivors (75 ±; 32 ms vs 63 ±; 35 ms, P = 0.01). After adjustment for age and sex in the Cox proportional hazards model, prolonged QTc dispersion (≧; 70 msec) predicted all‐cause mortality (relative risk [RR] 1.38, 95% confidence interval [Cl] 1.02–1.86) and particularly stroke mortality (RR 2.7, 95% Cl 1.29–5.73), but not cardiac (RR 1.38, 95% Cl 0.87–2.18) or cancer (RR 1.51, 95% Cl 0.91–2.50) mortality. After adjustment for age, sex, body mass index, blood pressure, blood glucose and cholesterol concentrations, functional class, history of cerebrovascular disease, diabetes, smoking, previous myocardial infarction, angina pectoris, congestive heart failure, medication, left ventricular hypertrophy on ECG, presence of atrial fibrillation and R‐R interval, increased QTc dispersion still predicted stroke mortality (RR 3.21, 95% Cl 1.09–9.47), but not total mortality or mortality from other causes. The combination of increased QTc dispersion and left ventricular hypertrophy on ECG was a powerful independent predictor of stroke mortality in the present elderly population (RR 16.52, 95% Cl 3.37–80.89). QTcmin (the shortest QTc interval among the 12 leads of ECG) independently predicted total mortality (RR 1.0082, 95% Cl 1.0028–1.0136, P = 0.003), cardiac mortality (RR 1.0191, 95% Cl 1.0102–1.0281, P < 0.0001) and cancer mortality (RR 1.0162, 95% Cl 1.0049–1.0277, P = 0.005).Conclusions: Increased QTc dispersion yields independent information on the risk of dying from stroke among the elderly and its component, QTcmin, from the other causes of death. A.N.E. 2001; 6(3):183–192