bluuebunny/crossref_metadata_2025 huggingface dataset:
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.
Infantile Chaotic Atrial Tachycardia: Association with Viral Infections
Authors: Harris J. Peter , Cecchin Frank , Perry James C.
Published: October 2006

Infantile chaotic atrial tachycardia is a rare, usually self‐limited arrhythmia that is frequently resistant to conventional antiarrhythmic therapy. In contrast to other arrhythmias in the pediatric population, a pathophvsiologic substrate has not been identified. Four infants who developed chaotic atrial tachycardia in the setting of documented adenovirus or coxsackie virus infections are presented. This association led to the speculation that transient multifocal atrial myocarditis could be the substrate for chaotic atrial tachycardia in some infants.
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
The Effect of Myocardial Surgical Revascularization on Left Ventricular Late Potentials
Authors: Can Levent , Kayikçioǧlu Meral , Halil Halil , Kültürsay Hakan , Evrengül Harun , Kumanlioǧlu Kamil , Turkoglu Cüneyt
Published: October 2006

Background: The presence of ventricular late potentials (LP) is an important indicator for the development of ventricular tachyarrhythmias due to ischemic heart disease. The effect of myocardial revascularization on LP has remained controversial. The purpose of this study was to determine whether complete myocardial surgical revascularization (CABG) documented by myocardial perfusion scintigraphy might alter the substrate responsible for LP.

Methods: Prospectively, enrolled patients undergoing elective CABG were evaluated with thallium‐201 myocardial perfusion scintigraphy and signal‐ averaged ECG pre‐ and postoperatively. SAECG recordings were obtained serially: before, 48–72 hours and 3 months after CABG. LPS were defined as positive if SAECG met at least two of Gomes criteria. Scintigraphies were performed pre‐and 3 months postoperatively for determination of the success of revascularization. Changes observed in SAECG recordings after CABG were compared between those with and without successful revascularization.

Results: CABG resulted in successful revascularization in 23 patients and was unsuccessful in 17 (no change or deterioration of the perfusion defects). Preoperative SAECG values were not different between groups except for RMS values. The incidence of LP decreased significantly postoperatively in patients with improved myocardial perfusion, whereas there were no changes in patients who did not have postoperative perfusion improvement (McNemar test, P < 0.05).

Conclusions: LPs disappear following the elimination of myocardial ischemia by complete surgical revascularization. Persistence of ischemia following CABG usually results in the persistence of late potentials. The incidence of ventricular arrhythmias is expected to be unchanged in these patients and they should be reevaluated for reinterventions. A.N.E. 2001;6(2):84–91
Effect of Beta‐Blockade on Autonomic Modulation of Heart Rate and Neurohormonal Profile in Decompensated Heart Failure
Authors: Aronson Doron , Burger Andrew J.
Published: October 2006

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
Differences in Heart Rate Dynamics Before the Spontaneous Onset of Long and Short Episodes of Paroxysmal Atrial Fibrillation
Authors: Vikman Saila , Yli‐Mäyry Sinikka , Mäkikallio Timo H. , Airaksinen K.E. Juhani , Huikuri Heikki V.
Published: October 2006

Background: Altered heart rate (HR) dynamics precede the spontaneous onset of atrial fibrillation (AF), but the factors related to the perpetuation and duration of paroxysmal AF episodes are not well established. This study was designed to test the hypothesis that HR dynamics preceding the onset of (AF) may influence the duration of AF.

Methods: Traditional time and frequency domain HR variability indices, along with a short‐term fractal scaling exponent (α1) and approximate entropy (ApEn), were analyzed in 20‐minute intervals before 92 episodes of spontaneous paroxysmal AF in 22 patients without structural heart disease. AF episodes were divided into two groups according to the duration of the arrhythmia episodes.

Results: The high‐frequency (HF) spectral component in normalized units (nu) of heart rate variability was higher and low‐frequency (LF) component lower before long (> 200 s, n = 41) compared to short (< 200 s, n = 51) AF episodes (HF nu; 40.1 ± 14.8 vs 31.5 ± 16.4, P < 0.0001 and LF nu; 59.9 ± 14.8 vs 68.5 ± 16.4, P < 0.0001). Short‐term scaling exponent values also were lower before long compared to short AF episodes (e.g., α1; 1.12 ± 0.21 vs 1.24 ± 0.23, P < 0.0001). Women had a larger number of long AF episodes than men, but the duration of AF was not related to any other clinical or demographic features or antiarrhythmic medication.

Conclusion: Increased HF oscillations and decreased short‐term correlation properties of R‐R intervals, reflecting altered sympathovagal balance before the onset of AF, predispose to perpetuation of spontaneous arrhythmia episodes in patients with vulnerability to paroxysmal AF and without structural heart disease. A.N.E. 2001;6(2):134–142
P‐Wave Dispersion: A Novel Predictor of Paroxysmal Atrial Fibrillation
Authors: Dilaveris Polychronis E. , Gialafos John E.
Published: October 2006

Background: The prolongation of intraatrial and interatrial conduction time and the inhomogeneous propagation of sinus impulses are well known electrophysiologic characteristics in patients with paroxysmal atrial fibrillation (AF). Previous studies have demonstrated that individuals with a clinical history of paroxysmal AF show a significantly increased P‐wave duration in 12‐lead surface electrocardiograms (ECG) and signal‐averaged ECG recordings.

Methods: The inhomogeneous and discontinuous atrial conduction in patients with paroxysmal AF has recently been studied with a new ECG index, P‐wave dispersion. P‐wave dispersion is defined as the difference between the longest and the shortest P‐wave duration recorded from multiple different surface ECG leads. Up to now the most extensive clinical evaluation of P‐wave dispersion has been performed in the assessment of the risk for AF in patients without apparent heart disease, in hypertensives, in patients with coronary artery disease and in patients undergoing coronary artery bypass surgery. P‐wave dispersion has proven to be a sensitive and specific ECG predictor of AF in the various clinical settings. However, no electrophysiologic study has proven up to now the suspected relationship between the dispersion in the atrial conduction times and P‐wave dispersion. The methodology used for the calculation of P‐wave dispersion is not standardized and more efforts to improve the reliability and reproducibility of P‐wave dispersion measurements are needed.

Conclusions: P‐wave dispersion constitutes a recent contribution to the field of noninvasive electrocardiology and seems to be quite promising in the field of AF prediction.

A.N.E. 2001;6(2):159–165
The Normal Sequence of Right and Left Atrial Contraction
Authors: Barletta Giuseppe , Del Bene Riccarda , Fantini Fabio
Published: October 2006

Objective: To study the sequence of atrial activation and the interatrial electromechanical delay (IEmD) noninvasively in healthy subjects during sinus rhythm (SR).

Methods and Results: In 66 SR healthy subjects P‐wave activation was analyzed by means of vectorcardiography. The timing of atrial contractions was measured as the intervals between the P‐wave and the A‐wave of the Doppler right and left ventricular inflows (P‐At and P‐Am), and IEmD was calculated as the algebraic difference PAm P‐At. In the horizontal plane the vectorcardiographic P‐loop was anteroposterior (“typical”, 41 subjects), anterior (18), or posterior (7). IEmD (mean ±; SE 17 ±; 8 ms) was directly related to R‐R and P‐R intervals. IEmD was significantly shorter in anterior and posterior P loops than in the typical (6.5 ±; 5.3 and 8.1 ±; 10.1, respectively, vs 24.2 ±; 3.1 ms). In the posterior P‐loop group, who exhibited longer P‐At, mitral E‐wave velocity and E/A ratio were reduced, and left atrial booster function was increased.

Conclusion: IEmD was widely variable in SR, reflecting the origin site of sinus impulse, which independently influenced ventricular filling dynamics. A.N.E. 2001;6(3):222–228
Familial Mahaim Syndrome
Authors: Ott Peter , Marcus Frank I.
Published: October 2006

We describe the occurrence of Mahaim syndrome in a mother and her son. The occurrence of such a rare disorder in two members of a family is noteworthy, has not been reported before, and suggests the possibility of genetic transmission. A genetic transmission of supraventricular tachycardia has been described only in rare cases for the Wolff‐Parkinson‐White syndrome. No such data is available for the Mahaim syndrome. A.N.E. 2001; 6(3):272–275
QRS Score: A Composite Index of Exercise‐Induced Changes in the Q, R, and S Waves During Exercise Stress Testing in Patients with Ischemic Heart Disease
Authors: Toth Ambrus , Marton Zsolt , Czopf Laszlo , Kesmarky Gabor , Halmosi Robert , Juricskay Istvan , Habon Tamas , Toth Kalman
Published: October 2006

Background: To detect ischemic heart disease, the exercise‐induced ST‐segment displacement is the most frequently used ECG parameter. However, the value of this marker was proven to be limited with varying sensitivity and specificity. A new parameter, called QRS score, emerged to improve the efficacy of exercise testing.

Methods: Our study aimed at evaluating the diagnostic value of QRS score in ischemic heart disease, investigating males and females separately, and examining the effects of heart rate and antiischemic medication. QRS score and cumulative ST depression were calculated in 212 patients and correlated to the findings of the stress myocardial perfusion SPECT (197 subjects) or coronary angiography (54 subjects).

Results: An inverse correlation could be found between the QRS score and the results of myocardial SPECT and coronary angiography in the whole population, especially in males; females did not show a significant relationship. In patients with conclusive tests (achieving 85% of the maximal predicted heart rate) QRS score correlated significantly with the results of the stress myocardial perfusion SPECT and coronary angiography. The sensitivity, specificity, and validity of the QRS score surpassed those of the cumulative ST depression in the entire population as well as in patients with conclusive tests. The antiischemic medication did not affect correlation values.

Conclusion: QRS score was significantly related to the extent of myocardial ischemia and the severity of coronary heart disease, thus along with the analysis of ST‐segment displacement may contribute to the more precise evaluation of exercise testing. A.N.E. 2001;6(4):310–318
The Prognostic Accuracy of Different QT Interval Measures
Authors: Lund Kaspar , Perkiömäki Juha S. , Brohet Christian , Elming Hanne , Zaïdi Mohammed , Torp‐Pedersen Christian , Huikuri Heikki V. , Nygaard Hans , Kirstein Pedersen Anders
Published: October 2006

Background: The QT intervals accuracy for predicting arrhvthmic death varies between studies, possibly due to differences in the selection of the lead used for measurement of the QT interval. The purpose of this study was to analyze the prognostic accuracy of all known ways to select the lead.

Methods and Results: Three institutions that used different methods for measuring QT intervals provided their QT databases. They included more than 3500 twelve‐lead surface ECGs. The data represented low‐ and high‐risk patients of the normal population (survivors vs dead from cardiovascular causes), acute myocardial infarction (survivors versus death from all causes) and remote myocardial infarction (with vs without a history of ventricular arrhythmia). The prognostic accuracy was defined as the area under the Receiver Operator Curve (ROC‐area). The most accurate standard leads were I and aVL and the least accurate was AVR. The most accurate precordial lead was V4. The prognostic accuracy of the longest QT interval was higher than for any standard lead. The prognostic accuracv of the mean of the three longest QT intervals was equal to or slightly lower than for the longest QT interval.

Conclusions: The highest prognostic accuracy is obtained with the longest QT interval. The accuracies of the lead selection methods are so different that it can explain a substantial part of the differences between otherwise similar studies in the literature. We recommend the use of the mean value of the three longest QT intervals. A.N.E. 2002;7(1):10–16
QT Dispersion and Viable Myocardium in Patients with Prior Myocardial Infarction and Severe Left Ventricular Dysfunction
Authors: Hun Li Vuy , Dorbala Sharmila , Narula Dhiraj , DePuey Gordon , Steinberg Jonathan S.
Published: October 2006

Background: QT dispersion (QTd) has been found to correlate to the amount of viable myocardium in patients with Q‐wave myocardial infarction and well‐preserved LV function. However, this relationship is unknown in patients with severe left ventricular dysfunction.

Methods: Thirty‐four patients with prior large myocardial infarction and severe left ventricular dysfunction underwent Tc‐99m sestamibi single photon emission cardiac tomography (SPECT) and F‐18 fluorodeoxyglucose (FDG) SPECT. Viability was defined as a defect relative count density (DCD) of at least 20% greater on FDG SPECT. QTd, corrected QT dispersion (QTcd), and QT coefficient of variation (cv) in patients with viable myocardium was compared to those without viable mvocardium in the infarct area.

Results: Thirteen patients were excluded from analysis for poor FDG images or inadequate ECG tracings. Of the remaining patients, 10 (48%) were found to have viability on FDG SPECT. QTd, QTcd, and QTcv in patients with viability were: 58 ± 22 ms, 61 ± 23 ms, and 4.81 ± 1.76%, respectively, which did not differ significantly from those in patients without viability (QTd = 56 ± 14 ms, QTcd = 70 ± 16 ms and Qtcv = 5.06 ± 1.20% (P = NS]). Moreover, neither FDG defect size, nor LVEF correlated with QTd.

Conclusions: This study indicates no relationship between QTd and viability in patients with myocardial infarction and severe left ventricular dysfunction. A.N.E. 2002;7(1):53–59
Lack of Impact of Myocardial Ischemia on the Signal‐Averaged ECG Assessment by Time‐Domain Analysis
Authors: Schneider Michael A. E. , Nienaber Christoph A.
Published: October 2006

Background: Late potentials represent an arrhythmogenic substrate in chronically infarcted myocardium. It is hypothesized that acute transient ischemia enhances anisotropic electrical ventricular activation and facilitates reentry mechanisms. Study aim was the prospective assessment of the impact of dipyridamole‐induced myocardial ischemia on the signal‐averaged ECG.

Methods: Dipyridamole stress thallium‐201 SPECT imaging was utilized to avoid noise contamination of the signal‐averaged ECG from exercise and to document evidence and localization of myocardial ischemia or persistent perfusion defects in 68 patients with suspected coronary artery disease. Before and during dipyridamole‐induced vasodilatation serial signal‐averaged ECG was performed to evaluate the influence of transient ischemia on the occurrence of late potentials.

Results: There was a significant difference between heart rate at rest and heart rate under dipyridamole influence in patients with inducible ischemia (70 ± 13 vs. 87 ± 13; P < 0.0001) in contrast to patients without dipyridamole‐induced ischemia (74 ± 20 vs. 80 ± 16; n.s.). The number of averaged beats and achieved noise level was comparable between both groups. Thirty‐three of 68 patients (49%) revealed dipyridamole‐induced ischemia; however, no changes of the SAECG parameters, such as QRS, RMS, LAS at 25–250 and 40–250 Hz bandpass filtering in the leads X, Y, Z and vector magnitude, respectively, were observed as a result of ischemia.

Conclusion: These results suggest that transient myocardial ischemia does not affect the signal‐averaged ECG. Clinically, the signal‐averaged ECG analysis seems not to be helpful in identifying patients with silent ischemia. A.N.E. 2002;7(3):191–197
Is the Change of Late Potential Over Time Related to Enzyme Levels?Ichemic Burden in Acute Myocardial Infarction
Authors: Eryol Namik Kemal , Topsakal Ramazan , Oguzhan Abdurrahman , Abaci Adnan , Başar Emrullah , Ergin Ali , Çetin Servet
Published: October 2006

Background: The ventricular late potential (VLP) detected using the technique of signal average electrocardiography (SAECG) interacts with several factors, primarily time.

Method: In this study, we examined the interaction, over time, of VLP with the initial ischemic burden and enzyme levels in acute myocardial infarction. Patients diagnosed as having acute myocardial infarction were included in the study. On the first day, the patients underwent enzyme analysis and electrocardiography (ECG) follow‐up every 6 hours. A 24‐hour ambulatory ECG was performed on the seventh day in order to determine the ischemic burden. SAECG findings (TQRS, RMS, LAS were obtained on the seventh day, in the first and third months. The study was continued with the patients who did not require angioplasty as decided with angiographic evaluation in the first month.

Results: The study included 30 patients with acute myocardial infarction (mean age 51 ± 12, 28 males and 2 females). The initial mean CK‐MB levels and the mean ischemic burden were 98 ± 31 U/L and 44 ± 96 minutes. The TQRS (ms), LAS (ms), and RMS (μV) values (mean ± SD) obtained at day 7, month 1, and month 3 are 97 ± 12, 96 ± 9, 103 ± 11, P = 0.01; 31 ± 10, 31 ± 11, 32 ± 10, P = 0.46; 43 ± 28, 41 ± 26, 33 ± 25, P = 0.01, respectively. We observed that the TQRS and RMS values changed significantly with time, but these levels of significance disappeared when adjusted for the initial ischemic burden and CK‐MB levels (P = 0.06; P = 0.53). The VLP frequency was 33% at day 7 and 23% at month 3. Unlike the CK‐MB level, the initial ischemic burden was significantly different between the patients with and without VLP at month 3 (150.85 ± 149.28, 12.34 ± 26.48, P = 0.001). When tested together with age and gender, it was found that the high initial ischemic burden increased the possibility of VLP (OR: 24, Cl: 2.09–279.52, P = 0.01) at month 3.

Conclusion: SAECG findings in patients with myocardial infarction changed with time; however, this change occurred depending on the initial ischemic burden and CK‐MB levels. Of these, only the initial ischemic burden, especially in high levels, was a determinant for the presence of VLP in the late period of myocardial infarction. A.N.E. 2002;7(3):242–246
Brugada Syndrome: Current Clinical Aspects and Risk Stratification
Authors: Ikeda Takanori
Published: October 2006

Brugada syndrome is a primary electrical disease of the heart that causes sudden cardiac death or life‐threatening ventricular arrhythmias, especially in younger men. Genetic analysis supports that this syndrome is a cardiac ion channel disease. A typical electrocardiographic finding consists of a right bundle branch block pattern and ST‐segment elevation in the right precordial leads. The higher intercostal space V1 to V3 lead electrocardiogram could be helpful in detecting Brugada patients. Although two types of the ST‐segment elevation are present, the coved type is more relevant to the syndrome than the saddle‐back type. These patterns can be present permanently or intermittently. Recent data suggest that the Brugada‐type electrocardiogram is more prevalent than the manifest Brugada syndrome. Asymptomatic individuals have a much lower incidence of future cardiac events than the symptomatic patients. Although risk stratification for the Brugada syndrome is still incomplete, the inducibility of sustained ventricular arrhythmias has been proposed as a good outcome predictor in this syndrome. In noninvasive techniques, some clinical evidence supports that late potentials detected by signal‐averaged electrocardiography are a useful index for identifying patients at risk. The available data recommend prophylactic implantation of an imptantabie cardioverter defibrillator to prevent sudden cardiac death. This review summarizes recent information of the syndrome by reviewing most of new clinical reports and speculates on its risk stratification. A.N.E. 2002;7(3):251–262
Support of Daily ECG Procedures in a Cardiology Department via the Integration of an Existing Clinical Database and a Commercial ECG Management System
Authors: Chiarugi Franco , Lombardi David , Lees Philip J. , Chronaki Catherine E. , Tsiknakis Manolis , Orphanoudakis Stelios C.
Published: October 2006

Background: In the context of HYGEIAnet, the regional health telematics network of Crete, a clinical cardiology database (CARDIS) has been installed in several hospitals. The large number of resting ECGs recorded daily made it a priority to have computerized support for the entire ECG procedure.

Methods: Starting in late 2000, ICS‐FORTH and Mortara Instrument, Inc., collaborated to integrate the Mortara E‐Scribe/NT ECG management system with CAROIS in order to support daily ECG procedures. CARDIS was extended to allow automatic ordering of daily ECGs via E‐Scribe/NT. The ECG order list is downloaded to the electrocardiographs and executed, the recorded ECGs are transmitted to E‐Scribe/NT, where confirmed ECG records are linked back to CARDIS. A thorough testing period was used to identify and correct problems. An ECG viewer/printer was extended to read ECG files in E‐Scribe/NT format.

Results: The integration of E‐Scribe/NT and CARDIS, enabling automatic scheduling of ECG orders and immediate availability of confirmed ECGs records for viewing and printing in the clinical database, took approximately 4 man months. The performance of the system is highly satisfactory and it is now ready for deployment in the hospital.

Conclusions: Integration of a commercially available ECG management system with an existing clinical database can provide a rapid, practical solution that requires no major modifications to either software component. The success of this project makes us optimistic about extending CARDIS to support additional examination‐procedures such as digital coronary angiography and ultrasound examinations. A.N.E. 2002;7(3):263–270
Adrenergic Nervous System Influences on the Induction of Ventricular Tachycardia
Authors: Pellizzón Oscar A. , Beloscar Juan S. , Mariani Enrique
Published: October 2006

Background: Sudden cardiac death is a major cause of mortality in western countries and the ventricular tachyarrhythmias are mainly involved in this regard. The adrenergic autonomic nervous system has influences in provoking life‐threatening arrhythmias, and the prevention of such arrhythmias with beta‐blockers supports this viewpoint. To evaluate the effect of the adrenergic nervous system and some catecholamine‐releasing stimuli on the induction of ventricular tachycardia, we decided to explore the occurrence of ventricular tachycardia in patients subjected to three consecutive tests, exercise testing, isoproterenol infusion, and mental stress.

Methods: Nineteen subjects who experienced exercise test‐induced ventricular tachycardia were subjected to an isoproterenol infusion and mental stress. All but one patient had cardiac disease, with 70% due to Chagas’disease. Seventeen of the 19 study subjects had normal ventricular function.

Results: Exercise test‐induced ventricular tachycardia was nonsustained in 17 patients and sustained in 2 cases. Isoproterenol infusion induced nonsustained ventricular tachycardia in 9 of 19 patients. Mental stress, on its own, was able to induce nonsustained ventricular tachycardia in 2 of 19 patients.

Conclusions: Among patients preselected for exercise‐induced ventricular tachycardia, almost half could be induced into ventricular tachycardia by isoproterenol infusion. Mental stress was a less powerful inducer of ventricular arrhythmias in this study group. A.N.E. 2002;7(4):281–288
Beat‐to‐Beat Repolarization Variability Measured by T Wave Spectral Variance Index in Chronic Infarcted Animals
Authors: Valverde Esteban RaúI , Quinteiro Ricardo Alberto , Arini Pedro David , Bertrán Guillermo Claudio , Biagetti Marcelo Oscar
Published: October 2006

Background: Recent experimental and clinical studies have shown that beat‐to‐beat variability of repolarization morphology is associated with an increased risk for developing malignant ventricular arrhythmias. However, few data exist on the relationship between beat‐to‐beat repolarization variability and myocardial infarction itself.

Methods and Results: In the present work we tested the algorithm of T wave spectral variance (TWSV) using the two dimension fast Fourier transform, in an animal model of myocardial infarction to extend the evidences that support the existence of beat‐to‐beat alteration in repolarization during the chronic stage of myocardial infarction. Thirty‐four New Zealand rabbits were included in the study and divided in two groups. Group I (N = 24) exposed to surgical ligation of the left anterior descendent coronary artery. Group II (N = 10) sham operated animals. The TWSV index was calculated before and after 15 and 45 days of surgery. Both groups showed significant increments in TWSV after 15 days postsurgery. However, while the sham animals return to its control value, the infarcted group exhibited values of the TWSV index that remains significantly high after 45 days of surgery, with a mean increment of 28.7% (P <0.05 against sham). Moreover, when the infarcted group was qualitatively divided in three subgroups, according to its infarction areas, a trend was found in the correlation between the magnitude of the infarcted area and the TWSV index.

Conclusion: This noninvasive measure confirms the presence of temporal repolarization variability associated with chronic myocardial infarction and further contributes to identify the infarcted animals. A.N.E. 2002;7(4):319–325
Macroporous Ceramics from Particle‐Stabilized Wet Foams
Authors: Gonzenbach Urs T. , Studart André R. , Tervoort Elena , Gauckler Ludwig J.
Published: October 2006

We present a novel direct‐foaming method to produce macroporous ceramics using particles instead of surfactants as stabilizers of the wet foams. This method allows for the fabrication of ultra‐stable wet foams that resist coarsening upon drying and sintering. Macroporous ceramics of various chemical compositions with open or closed cells, average cell sizes ranging from 10 to 300 μm and porosities within 45% and 95%, can be easily prepared using this new approach. The sintered foams show high compressive strengths of up to 16 MPa in alumina foams with porosities of 88%.