bluuebunny/crossref_metadata_2025_split huggingface dataset:
Clinical and Electrocardiographic Variables Can Predict Atrial Fibrillation in Patients with Atrioventricular Accessory Pathways
Authors: D'Avila André , Scanavacca Mauricio , Reolão Basileo , Darrieux Francisco , Savalli Carine , Sosa Eduardo 
Published: October 2006

Background:Risk stratification of sudden death in patients with Wolff‐Parkinson‐White syndrome is based on the refractory period of the atrioventricular accessory pathway and the probability of spontaneous atrial fibrillation. Risk stratification based on invasive studies does not seem cost‐effective in the radiofrequency ablation era, and, although sensitive, noninvasive tests are not used because of their low specificity. We sought to determine whether clinical and electrocardiographic variables can predict spontaneous atrial fibrillation in patients with an accessory pathway. Methods:We studied 420 consecutive patients treated by radiofrequency catheter ablation who had a single atrioventricular accessory pathway and the Influence of four variables: age, gender, location of the accessory pathway as determined by the site of successful radiofrequency ablation, and the presence of a manifest accessory pathway in the ECG was analyzed by multiple logistic regression analysis and a chi‐square test. The development model, comprised of data from the first 359 patients, included 58 patients with spontaneous atrial fibrillation and 301 patients without spontaneous atrial fibrillation during follow‐up. The likelihood ratio derived from the development model was validated in the last 61 patients. Results:Patients with spontaneous atrial fibrillation occurring before accessory pathway ablation were more often male and were older than those without atrial fibrillation. Atrial fibrillation occurred more frequently in manifest than in concealed accessory pathways, and the presence of posteroseptal accessory pathway strongly correlated with spontaneous atrial fibrillation. Conclusion:The probability of spontaneous atrial fibrillation was higher in men with a manifest posteroseptal accessory pathway and increased with age. A.N.E. 2000;5(1):45–52
Effects of Myocardial Perfusion on QT Dispersion in Patients with Hypertrophic Cardiomyopathy
Authors: Yamanari Hiroshi , Fukushima Kengo , Miyaji Katsusi , Yamamoto Mika , Nagase Satoshi , Otsuka Fuyou Misunaga , Nakayama Kazuaki , Matsubara Hiromi , Emori Tetsuro , Ohe Tohru 
Published: October 2006

Background:In patients with hypertrophic cardiomyopathy (HCM), myocardial ischemia and myocardial fibrosis as well as ventricular tachyarrhythmia are frequently observed. An increase of heterogeneity of repolarization provided the development of ventricular tachyarrhythmia. The aims of the present study are to evaluate the influence of exercise‐induced myocardial perfusion abnormalities on QT dispersion and to assess whether QT dispersion was involved in ventricular tachycardia (VT) in patients with HCM. Methods:Thirty‐eight patients with HCM and 20 control subjects underwent an exercise stress test, and QT intervals were measured pre‐exercise and at 3 minutes after peak exercise. All subjects underwent thallium (TI)‐201 stress myocardial imaging, and their TI‐201 defect score and exerciseinduced myocardial ischemia were evaluated. Results:Twelve patients (31%) revealed sustained or nonsustained VT. The pre‐exercise QTc dispersion (QTcD) was significantly correlated with the Tl‐201 defect score (r = 0.61, P < 0.0001). The QTcD at 3 minutes after peak exercise was significantly greater in patients with exerciseinduced myocardial ischemia than without exercise‐induced myocardial ischemia (96 ± 36, 72 ± 24 ms1/2, P < 0.03). The QTcD at 3 minutes after peak exercise was significantly greater in patients with VT than without VT (111 ± 23, 64 ± 17 ms1/2, P < 0.0001). Conclusion:It is suggested that the degree of myocardial fibrosis influences the pre‐exercise QTcD, and exercise‐induced myocardial ischemia precipitates the increase in the QTcD at 3 minutes after peak exercise in patients with HCM. The increased QTcD at 3 minutes after peak exercise may play a role in identifying patients at a potentially higher risk. A.N.E. 2000;5(1):60–67
Electrocardiographic Quantitation of Heterogeneity of Ventricular Repolarization
Authors: Okin Peter M. , Xue Quizhen , Reddy Shankara , Kligfield Paul 
Published: October 2006

Background:QT interval dispersion (QTd) measured from the surface ECG has emerged as the most common noninvasive method for assessing heterogeneity of ventricular repolarization. Although QTd correlates with dispersion of monophasic action potential duration at 90% repolarization and with dispersion of recovery time recorded from the epicardium, total T‐wave area, representing a summation of vectors during this time interval, has been shown to have the highest correlation with these invasive measures of dispersion of repolarization. However, recent clinical studies suggest that the ratio of the second to first eigenvalues of the spatial T‐wave vector using principal component analysis (PCA ratio) may more accurately reflect heterogeneity of ventricular repolarization. Methods:To better characterize the ECG correlates of surface ECG measures of heterogeneity of ventricular repolarization and to establish normal values of these criteria using an automated measurement method, the relations of QRS onset to T‐wave offset (QTod) and to T‐wave peak (QTpd) dispersion and the PCA ratio to T‐wave area and amplitude, heart rate, QRS axis and duration, and the QTo interval were examined in 163 asymptomatic subjects with normal resting ECGs and normal left ventricular mass and function. QTod and QTpd were measured by computer from digitized ECGs as the difference between the maximum and minimum QTo and QTp intervals, respectively. Results:In univariate analyses, a significant correlation was found between the sum of the T‐wave area and the PCA ratio (R =−0.46, P < 0.001), but there was no significant correlation of the sum of T‐wave area with QTod (R = 0.11, P = NS) or QTpd (R=0.09, P = NS). There were only modest correlations between QTod and QTpd (R = 0.45) and between the PCA ratio and QTod (R = 0.29) and QTpd (R = 0.49) (each P < 0.001). In stepwise multivariate linear regression analyses, the PCA ratio was significantly related to the sum of T‐wave area, T‐wave amplitude in aVL, and to female gender (overall R = 0.54, P < 0.001), QTod correlated only with the maximum QTo0 interval (R = 0.39, P < 0.001), and QTpd was related to heart rate and QRS axis (overall R = 0.36, P <0.001). In addition, the normal interlead dispersion of repolarization as measured by QTod was significantly greater than dispersion measured by QTod (23.5 ± 11.5 ms vs 18.3 ± 11.2 ms, P < 0.001). Conclusions: These findings provide new information on ECG measures of heterogeneity of repolarization in normal subjects, with a significantly higher intrinsic variability of Q to T‐peak than Q to T‐offset dispersion and only modest correlation between these wo measures. The independent relation of the PCA ratio to the sum of T‐wave area suggests that the PCA ratio may be a more accurate surface ECG reflection of the heterogeneity of ventricular repolarizat on. A.N.E. 2000;5(1):79–87
Evaluation of QT Interval Dispersion in a Multiple Electrodes Recording System versus 12‐Lead Standard ECG in an In Vitro Model
Authors: Arini Pedro David , Quinteiro Ricardo Alberto , Valverde Esteban Raúl , Bertran Guillermo Claudio , Biagetti Marcelo Oscar 
Published: October 2006

Background: QT interval dispersion (QTID) as assessed on conventional surface electrocardiogram (ECG) has been used as a clinical tool to identify patients at high risk of ventricular arrhythmia. However, the results obtained have been controversial. The main purpose of this study was to compare QTID measured from an array of 5 × 6 electrodes homogeneously distributed against the values found when the 12‐lead standard ECG was used.Methods: QTID was calculated in a modified Langendorff‐perfused rabbit heart model immersed in a cylindrical chamber. Dispersion in ventricular repolarization was artificially increased by d‐sotalol (60 μ;m) perfusion.Results: All the duration variables measured from any of the lead systems used were significantly increased after d‐sotalol perfusion. The most commonly used variables in clinical studies, such as QTID (maximum ‐ minimum), do not reach a level of statistical significance, except when measured from the 30‐electrodes array or 15 electrodes covering the left or right side of the heart. The standard deviation of the QT interval (QTI) hardly reached a significant level (P = 0.0499) when calculated from the 12‐lead standard ECG. QTID measured at the peak of the T wave exhibited the highest level of significance when calculated from any of the lead systems used.Conclusion: Thirty electrodes homogeneously distributed on the body surface can better discriminate changes in heterogeneity of repolarization. These data further support the importance of multiple recording systems for the evaluation of QTID and may help to provide an understanding of the discrepancies found in clinical applications.
Agreement Between Automatic and Manual Measurement of Atrial and Ventricular Signal‐Averaged Electrocardiograms in Healthy Subjects
Authors: Savelieva Irina , Aytemir Kudret , Hnatkova Katerina , Camm A. John , Malik Marek 
Published: October 2006

Background: Although prolonged duration of the signal‐averaged (SA) P wave has been proposed as a noninvasive marker of atrial arrhythmias, clinical value of atrial SAECG is limited, largely due to the difficulty with detection of the onset and offset of the high gain P wave. The aim of this study was to assess the reliability of automatic measurement of the atrial SAECG.Methods: Fifty‐one healthy volunteers (30 men; 32 ± 8 years) underwent a session of 3 atrial and 3 ventricular SAECG recordings. Automatically detected onset and offset of SA QRS complex (QRStot) and SA P wave (Ptot) were subsequently‐corrected by two independent observers. For ventricular SAECG, three conventional time‐domain parameters were calculated. For atrial SAECG, the following five parameters were measured: Ptot, root mean square voltages of the entire Ptot (RMS‐P) and of the terminal 40, 30, and 20 ms of Ptot. Relative errors of the different pairs of measurements were used to assess the interobserver and observer‐computer variability. The Bland‐Altman method was applied to express the agreement between measurements.Results: Although the mean interobserver relative errors were low for QRStot and Ptot (1.1% vs 1.5%), the observer‐computer error was significantly higher for Ptot than for QRStot (1.7% vs 7.1%; P < 0.0001). For the voltage parameters, the lowest interobserver and observer‐computer relative errors were found for RMS‐P (6.6% vs 7.3%, P = ns). For RMS voltages of the terminal 40–20 ms of Ptot, relative errors exceeded 10%, but the interobserver error was significantly lower than the observer‐computer error (P < 0.0001).Conclusion: Automatic detection of the SA P‐wave onset and offset is unreliable and the atrial SAECG requires manual correction. Given a good interobserver agreement, such a correction is unlikely to introduce any significant observer‐dependent bias. A.N.E. 2000; 5(2):133–138
Normal Values for Time‐Domain, Frequency‐Domain, and Spectral Turbulence Analyses of Signal‐Averaged Electrocardiograms in Healthy Subjects
Authors: Nakazato Yuji , Nakata Yasuro , Nakazato Kaoru , Yasuda Masayuki , Sumiyoshi Masataka , Yamaguchi Hiroshi , Moroe Kazuo , Ebato Mio , Iwa Toru 
Published: October 2006

Background: Signal‐averaged electrocardiograms (SAE) have mainly been studied in high risk patients with ischemic heart disease. A systemic study of the normal values and the comparative results using analytical methods has not been reported.Methods: We recorded SAE results in 200 apparently healthy subjects (100 males and 100 females, average age 28.9 years). The obtained signals were analyzed by for the time‐domain (TD), frequencydomain (fast Fourier transform [FFT]), and spectral turbulence (ST) analyses. The normal values for these parameters, including differences according to gender, were evaluated. The correlation between body characteristics and individual measurements was also evaluated for each analytical method. Results were compared using previously reported criteria and gender‐specific criteria.Results: The normal values for TD and FFT analyses, but not ST analysis, showed differences related to gender. A significant correlation was observed between the body characteristics noted in the TD and the FFT analyses, but this correlation was not seen for all parameters in the ST analysis. According to the conventional criteria, the rate of positive diagnosis was 9% for TD analysis, 4.5% for FFT analysis, and 2% for ST analysis. When gender‐specific criteria were applied, it was 1% for TD analysis, 3.5% for FFT analysis, and 0.5% for ST analysis. However, the positive results for subjects that were found using TD analysis were discordant with the results found using FFT and ST analyses in those subjects.Conclusions: The normal values for TD and FFT analyses showed gender‐related differences that were not seen using ST analysis. Gender‐specific criteria are recommended when using TD analysis because it decreased positive results for healthy subjects. However, as discordant results were obtained among the various analyses, the selection of the method for analyzing the SAE and interpretation of the results should be performed with caution.
Ventricular Late Potentials Are Associated with the Presence of Viable Myocardium After Anterior Myocardial Infarction
Authors: Tarricone Diego , Verzoni Alessandro , Di Leo Claudio , Bestetti Alberto , Tagliabue Luca , Del Sole Angelo , Cavenaghi Giorgio , Tarolo Gian Luigi , Fiorentini Cesare , Lombardi Federico 
Published: October 2006

Background: The aim of the study was to evaluate the relationship between myocardial viability (MV) detected by Tl‐201 rest/redistribution protocol (RR‐SPECT) and the presence of ventricular late potentials (VLPs) in acute myocardial infarction (AMI). We analyzed signal‐averaged ECGs (SAECGs) in 28 patients (age 57 ± 10 years) with a first anterior AMI within 48 hours of symptoms (SAECG1) and prior to discharge (SAECG2). VLPs were defined according to the presence of filtered QRS (QRS‐D) > 114 ms and duration of low amplitude signals (LAS) a 30 ms or root mean square voltage (RMS40) < 25 μ;V, using a 25‐Hz filter, or a duration of LAS > 39 ms or RMS40 < 20 μ;V, using a 40‐Hz filter. RR‐SPECT was performed 17 ± 6 days after AMI. Segments were considered viable when counts were > 60% in early images or when a fill‐in > 10% was detectable on delayed images of those segments with a first count between 31% and 59%.Methods: Patients were divided into two groups: with MV (group 1 = 16 patients) if almost one third of segments appeared to be viable; without MV (group 2 = 12 patients). No difference was found between the two groups in SAECG1, whereas, using a 25‐Hz filter, a greater QRS‐D (106.6 ± 13.5 vs 93.5 ± 6 ms) and LAS (31.2 ± 8.7 vs 18.1 ± 6.4 ms) as well as a smaller RMS40 (43 ± 33.5 vs 71.3 ± 30.4 μ;V) characterized the SAECG2 of group 1. Sensitivity and specificity of VLPs in detecting MV were 31% and 100%. When using cut‐off values derived from median distribution of the population (QRS‐D & 99 ms, LAS a 24 ms and RMS40 > 51 μ;V), sensitivity raised to 75% and specificity was 92% with a positive and negative predictive value of 92% and 73%.Conclusions: The presence of MV is associated with a greater incidence of VLPs. SAECG performed at the time of discharge may facilitate the identification of patients with μ;V after anterior AMI.
Automatic Filtering of R‐R Intervals for Heart Rate Variability Analysis
Authors: Machado Andrés , Migliaro Eduardo R. , Contreras Paola , Coro Frank 
Published: October 2006

Background: In R‐R analysis for heart rate variability, rhythm modificatipns other than those related to autonomic nervous system activity must be avoided. We describe an algorithm that performs a correction based on the comparison of each interval with a normal standard.Methods: Starting with a given R‐R list, a parameter R between 0 and 1 is chosen, the normal R‐R range is defined as: (1‐R, 1+R]. The first interval then is divided by the mode of the entire R‐R list. If the resulting value lies within the normal range, then it could be accepted as normal. Subsequent intervals are divided by the last accepted one and the mean value of the accepted intervals. If either of these results is inside.the normal range, then the considered interval is accepted. The abnormal intervals are evaluated to find out if they are in the expected range, which is [T‐1, T+11, where T is a new parameter smaller than R. Not expected intervals are handled differently to be corrected and in a few cases are eliminated.Results: Two types of tests were carried out. One uses real recordings containing artifacts. The other test was carried out by means of a computer program that generates corrupted data. R value was set in 0.2 and T in 0.05. Comparisons between our filter and other automatic algorithms were done.Conclusions: Our filter is fast and strong enough to perform an accurate automatic correction.
R‐Wave Detection by Subcutaneous ECG. Possible Use for Analyzing R‐R Variability
Authors: Fotuhi Parwis , Combs William , Condie Cathy , Theres Heinz , Schneider Tino , Stangl Karl , Baumann Gert 
Published: October 2006

Background: Atrial arrhythmia (AA) discrimination remains a technological challenge for implanted cardiac devices. We examined the feasibility of R‐wave detection by a subcutaneous far field ECG (SFFECG) and analysis of these signals for R to R variability as an indicator of atrial arrhythmia (AA).Methods: Surface ECG and SFFECG (from the pacemaker pocket) were recorded in sixteen patients (61.5 ± 11.4 years) with AA. The SFFECG was recorded with a pacemaker sized four electrode array acutely placed in the pacemaker pocket during implantation. The signals were analyzed to obtain peak‐to‐peak R wave amplitude and R to R interval variability (indicative of AAs).Results: In sixteen patients R waves were visually discernible in all recordings. The percentage over and under detection for automatic R wave recognition SFFECG was 3 and 9%, respectively. R to R variability analysis using the SFFECG produced results concordant to those using the surface ECG.Conclusion: SFFECG might be a helpful adjunct in implantable device systems for detection of R waves and may be used for measurement of R to R variability. A.N.E. 2001;6(1):18–23
Efficiency and Cost Saving of 7 Day Per Week Exercise Testing Utilizing All Electrocardiography Technologists
Authors: Smith Gis , Mooney Donna , Davey Louanne , Nebo Laura , Irwin Marleen E. , Senaratne Manohara P. J. 
Published: October 2006

Background: In most centers, exercise testing (ET) is performed by one or two trained technologists during the weekdays (0800 hours‐1600 hours), leaving a void during evenings and weekends. This leads to unnecessary increased costs due to delays in management of patients. Electrocardiography technologists (ECGT) are often available for extended hours. This project was undertaken to improve the efficiency of the ET laboratory by using ECGT to perform ET during these extended hours.Methods: Clinical utility and cost saving of a 7 day per week ET for management of patients with suspected and/or known coronary artery disease utilizing ECGT was assessed after adequate training. Of 4099 patients undergoing ET between January 1995 and December 1997, 810 tests performed by ECGT were reviewed retrospectively.Results: Of the 810 patients (age mean 58.4 ± 0.44 yrs; range 16–88; males: 508, females: 302), 806 (99.5%) underwent the Bruce protocol. The indications were: diagnostic, 61.3%, predischarge acute myocardial infarction (AMI), 17.7%, evaluation of angina, 19.6%, other, 1.4%. Only 8 (0.1%) patients had complications (prolonged chest pain, 6; nonsustained ventricular tachycardia, 2) with no AMIs or deaths. This strategy resulted in a savings of 158 bed days (Can$189,600) on inpatients and 15 bed days (Can$18,000) on those presenting to the emergency department.Conclusions: This study demonstrates the feasibility and safety of utilizing ECGT for ET thus extending the hours of service. This resulted in efficient patient management, with a considerable cost‐saving to the hospital. A.N.E. 2001;6(1):32–37
The Frequency Analysis of Signal‐Averaged ECG of P Wave as Predictor of Efficacy of Class III Antiarrhythmic Drugs to Maintain Sinus Rhythm in Recurrent Idiopathic Atrial Fibrillation
Authors: Barbosa Eduardo Corrêa , Barbosa Paulo Roberto Benchimol , Ginefra Paulo , de Souza Bomfim Alfredo , Boghossian Silvia Helena Cardoso , José da Rocha Plínio , Filho Francisco Manes Albanesi 
Published: October 2006

Background: The use of class III antiarrhythmic drugs (ADIII) has been considered a good predictor of sinus rhythm in patients post‐cardioversion from atrial fibrillation (AF). Several studies using frequency domain analysis of signal‐averaged ECG (FDSAECG) of the P wave were able to identify patients at risk for AF. The aim of this study was to assess the FDSAECG in predicting recurrence of idiopathic persistent AF (IPAF) in patients under ADIII therapy.Methods: In 33 patients with two or more previous symptomatic episodes of IPAF, despite classes I and II therapy, the FDSAECG of the P wave was performed during sinus rhythm and free‐drug state. The parameters were the mean and standard deviation of the frequency intersegmentar spectral correlation and the standard deviation of the signal frequency edge track. During the follow‐up of 30 ± 18 months, all patients received either amiodarone or sotalol.Results: During the follow‐up, the patients were divided into two groups: Group I—frequent recurrence (≧ three events/year; 16 patients), and Group II—infrequent recurrence (< three events/ year; 17 patients). With appropriate cutoff points for each parameter analyzed, intense fragmented electrical activity defined by the presence of at least two abnormal criteria were observed in 13 of 16 patients group I and in 3 of 17 patients group II (P = 0.0003). Sensitivity, specificity, positive and negative predictive values for frequent recurrence were 81.3, 82.4, 81.3, and 82.4, respectively.Conclusions: The results suggested that FDSAECG analysis of the P wave accurately predicted patients whose ADIII therapy will be effective in maintaining the sinus rhythm without frequent recurrence of IPAF. A.N.E. 2001;6(1):43–49