Journal of Electrocardiology

ECG and VT/VF Symposium

Marek Malik — 2010-01-01

For a number of decades, one of the major applications of electrocardiography has been in the diagnosis, classification, and monitoring of cardiac rhythm disorders. More recently, electrocardiographic research extended this area to include stratification of susceptibility to arrhythmias and characterization of underlying pathophysiologic processes. Judging from the number of publications on the topic and from the number of dedicated sessions at meetings of different learned societies, scientific and clinical interest in these electrocardiographic applications is vastly growing. I was therefore pleased when the Editor-in-Chief of this Journal asked me to assess uninvited articles that have presently been accepted for publication with the aim of composing a symposium dedicated to the broad area of electrocardiographic and electrophysiologic setting of ventricular tachycardia and fibrillation.

Electrocardiogram screening of infants for long QT syndrome: survey of pediatric cardiologists in North America

Ruey-Kang R. Chang, Sandra Rodriguez, Michelle Z. Gurvitz — 2009-08-10

Abstract: Objectives: The aim of this study was to evaluate current opinions toward screening infants for long QT syndrome (LQTS) by electrocardiogram (ECG) among pediatric cardiologists in North America.Background: Research from Italy shows that ECG screening of infants for LQTS is cost-effective.Methods: E-mail invitations were sent to 1045 pediatric cardiologists in North America listed in the American Academy of Pediatrics directory. The survey was Internet-based with multiple choice questions. Two repeat e-mail reminders were sent after the initial invitation.Results: Three sixty-three (35%) responses were returned. Among the respondents, 40% had more than 20 years of clinical experience, 32% had 10 to 20 years, 21% had 5-10 years, and 6% had less than 5 years. Thirty-one percent of respondents agreed and 41% disagreed that screening LQTS may decrease the incidence of sudden infant death syndrome. When asked if an ECG between 2 and 4 weeks of life can be used to screen newborns for LQTS, 47% agreed and 33% disagreed. To the question: “pediatricians should offer families the option of 12-lead ECG at baby's 2-week visit for detecting an uncommon but potentially lethal disease,” 27% agreed and 49% disagreed. When asked if there should be a mandate for ECG screening of all newborns, 11% agreed and 69% disagreed. The support for a mandate of ECG screening decreases with increasing number of years of experience (P = .03).Conclusions: Most pediatric cardiologists in North America remain skeptical about ECG screening of infants for LQTS. Among pediatric cardiologists, current support for ECG screening at pediatrician's offices is low, and only 10% would agree to a mandate for ECG screening.

QT dynamicity, microvolt T-wave alternans, and heart rate variability during 24-hour ambulatory electrocardiogram monitoring in the healthy newborn of first to fourth day of life

2010-01-01

Abstract: Background: Twenty-four hour ambulatory electrocardiogram (AECG) monitoring is an established technique for integrated assessment of heart rhythm; however, comprehensive description of serial changes in cardiac electrophysiology over the first days of life in humans is lacking. The aim of this study was to determine the patterns of circadian heart rhythm based on AECG evaluation in newborns.Methods: Twenty healthy newborns (14 boys and 6 girls) were serially examined with AECG at days 1, 2, and 4 after birth. Heart rate (HR), arrhythmias, QT dynamicity, microvolt T-wave alternans, and various indices of HR variability (HRV) including deceleration/acceleration capacity analysis were analyzed.Results: There were no sex differences in HR. Supraventricular premature beats were noted in 35%, ventricular—in 15 % of newborns. Slope QT/RR was 0.35 (0.3-0.5); intercept QT/RR was 124 (93-148), QT/RR correlation coefficient (r) was 0.63 (0.53-0.85). Peak value of T-wave alternans was 32 ± 8 (12-55) μV. Low level of HRV was typical for all parameters of time-domain analysis compared with normal limits for older children. The overall mean values of deceleration/acceleration capacity were 3.38 ± 0.57 (2.16-4.13) and −3.58 ± 0.67 (−2.13 to −4.38) milliseconds, respectively.Conclusion: The healthy newborns exhibit peculiarities of 24-hour cardiac rhythm with isolated premature beats, pauses of sinus rhythm less 1000 milliseconds, steep slope of QT/RR by analysis of QT dynamicity. There are low HRV, and symmetrical AC/DC capacity was typically for autonomic regulation of HR, probably due to high sympathetic activity at this age.

Beat-to-beat interplay of heart rate, ventricular depolarization, and repolarization

György Kozmann, Kristóf Haraszti, István Préda — 2009-10-12

Abstract: To improve malignant arrhythmia risk stratification, the causal and random components of spatiotemporal dynamics of heart rate (RR distances), ventricular depolarization sequence, and repolarization disparity were studied based on body surface potential map records taken for 5 minutes, in resting, supine position on 14 healthy subjects (age range, 20-65 years) and on 6 arrhythmia patients (age range, 59-70 years). Beat-to-beat QRS and QRST integral maps, Karhunen-Loève (KL) coefficients, RR, and nondipolarity index time series were computed. Tight relationship was found between RR and QRS integrals in healthy subjects with less association in arrhythmia patients. Tight KL-domain multiple linear association (r2 > 0.72) was found between the QRS and QRST integral dynamics (ie, depolarization sequence and repolarization disparity). Beat-to-beat probability of the generation of significant nondipolarity index spikes was proportional to the QRST KL-component standard deviations (SDi) and inversely proportional with the mean dipolar KL components (Mi) of the average QRST integral map.

Two automatic QT algorithms compared with manual measurement in identification of long QT syndrome

2010-01-01

Abstract: Background: Long QT syndrome (LQTS) is an inherited disorder that increases the risk of syncope and malignant ventricular arrhythmias, which may result in sudden death.Methods: We compared manual measurement by 4 observers (QTmanual) and 3 computerized measurements for QT interval accuracy in the diagnosis of LQTS:The population consisted of 94 genetically confirmed carriers of KCNQ1 (LQT1) and KCNH2 (LQT2) mutations and a combined control group of 28 genetically confirmed noncarriers and 66 unrelated healthy volunteers.Results: QTVCG provided the best combination of sensitivity (89%) and specificity (90%) in diagnosing LQTS, with 0.948 as the area under the receiver operating characteristic curve. The evaluation of QT measurement by the 4 observers revealed a high interreader variability, and only 1 of 4 observers showed acceptable level of agreement in LQTS mutation carrier identification (κ coefficient >0.75).Conclusion: Automatic QT measurement by the Mida1000/CoroNet system (Ortivus AB, Danderyd, Sweden) is an accurate, efficient, and easily applied method for initial screening for LQTS.

Reference values of electrocardiogram repolarization variables in a healthy population

2009-09-09

Abstract: Introduction: Reference values for T-wave morphology analysis and evaluation of the relationship with age, sex, and heart rate are lacking in the literature. In this study, we characterized T-wave morphology in a large sample of healthy individuals.Method: A total of 1081 healthy subjects (83% men; range, 17-81 years) were included. T-wave morphology variables describing the duration, area, slopes, amplitude, and distribution were calculated using 10-second digital electrocardiogram recordings. Multivariate regression was used to test for dependence of T-wave variables with the subject age, sex, and heart rate.Results: Lead V5 (men vs women) T-wave variables were as follows: amplitude, 444 versus 317 μV; area, 48.4 versus 33.2 ms ⁎ mV; Tpeak-Tend interval, 94 versus 92 milliseconds; maximal descending slope, −5.15 versus −3.69 μV/ms; skewness, −0.24 versus −0.22; and kurtosis, −0.36 versus −0.35. Tpeak-Tend interval, skewness, and kurtosis were independent of age, sex, and heart rate (r2 < 0.05), whereas Bazett-corrected QT-interval was more dependent (r2 = 0.40).Conclusion: A selection of T-wave morphology variables is found to be clinically independent of age, sex, and heart rate, including Tpeak-Tend interval, skewness, and kurtosis.

Ventricular Tachycardia?

Kurt S. Hoffmayer, Nora Goldschlager — 2009-04-22

Giant Inverted T waves in the emergency department: case report and review of differential diagnoses

Jayasree Pillarisetti, Kamal Gupta — 2009-09-25

Abstract: Inverted T waves are frequently seen in electrocardiograms (ECGs) and may represent a myriad of pathologies or nonspecific change. However, deep (giant) inverted T waves are only seen in a few clinical conditions. Presence of giant T waves should generally prompt investigations for apical (Yamaguchi) variant of hypertrophic cardiomyopathy, raised intracranial pressure, severe myocardial ischemia, posttachycardia syndrome, and others. This report describes an unusual case of moderate but not massive pulmonary embolism presenting with an ECG finding of giant inverted T waves. A review of the common conditions associated with such an ECG is also presented.

Detection of U wave activity in healthy volunteers by high-resolution magnetocardiography

2009-07-16

Abstract: Introduction: The purpose of our study was to prove the existence of the U wave using magnetocardiograms (MCGs).Methods: The 31-channel MCGs of 25 healthy volunteers were recorded. The onset of the U wave was defined by newly developed spatial correlation analysis; and the end, by different approaches.Results: A U wave could be proved in all volunteers. In 10 volunteers (heart rate, 57 ± 19 beats/min) in whom the U wave was found to be separated from the following P wave, the U wave's end could be determined as a threshold value (U wave duration, 310 ± 24 milliseconds). In 15 volunteers (heart rate, 70 ± 38 beats/min), the end of the U waves was concealed by a continuous transition of the U waves into the following P waves.Conclusions: The U wave seems to be a regular phenomenon and has a distinct spatiotemporal assembly.

Filtered QRS duration on signal-averaged electrocardiography correlates with ventricular dyssynchrony assessed by tissue Doppler imaging in patients with reduced ventricular ejection fraction

2009-07-16

Abstract: Objectives: The relationships between filtered QRS duration and ventricular dyssynchrony were studied.Methods: We measured filtered QRS duration on signal-averaged electrocardiography and analyzed tissue Doppler imaging in chronic heart failure patients with ejection fraction less than 50%.Results: In 64 patients, interventricular and intraventricular dyssynchronies were observed in 25 and 38 patients, respectively. All patients with interventricular dyssynchrony were associated with intraventricular dyssynchrony. Filtered QRS showed 0.82 and 0.78 of the area under the curve (AUC) in the receiver operating characteristic curve (ROC) for the detection of interventricular and intraventricular dyssynchrony, respectively, with 89.7% and 96.2% specificity and 52.0% and 52.6% sensitivity, with cutoff values of 174 and 153 milliseconds. Specificity and sensitivity as well as AUC were lower in the ROC of QRS duration than filtered QRS duration.Conclusion: Filtered QRS duration provided more reliable information to estimate ventricular dyssynchrony in patients with reduced ventricular ejection fraction than QRS duration did.

Relationship between T-wave alternans magnitude and the corresponding T-wave height

John E. Madias — 2009-09-02

I enjoyed very much reading the study by Doshi and Idriss published ahead of print in the Journal of Electrocardiology on July 16, 2009, because these authors embarked to explore fundamental issues pertaining to T-wave alternans (TWA) by using a 1-dimensional myocardial fiber computer model. One hopes that by using simple myocardial models, several outstanding issues that encumber the TWA technology may become eventually unraveled. Some of them include the following: (1) whether the magnitude of TWA is of any physiologic significance or the mere detection of the phenomenon above the noise level, or an agreed-upon threshold (eg, ≤1.9 μV) suffices for characterization of a serious proarrhythmic risk; (2) the short-term reproducibility (hours to days, to few weeks) of TWA in patients who are seemingly stable clinically, because one should not expect long-term reproducibility in any test performed in patients with cardiovascular illnesses, which are expected to show progression even with optimal therapy; (3) the influence of the different leads on the magnitude, or even the mere detection, of TWA; and (4) whether variations in the magnitude of the TWA could be traced to variation in the amplitude/morphology of the corresponding T waves or, even more accurately, of the corresponding J-T intervals.

Simultaneous mapping of endocardium and epicardium from multielectrode intrachamber and intravenous catheters: a computer simulation-based validation

Engin Baysoy, Uğur Cunedioğlu, Bülent Yılmaz — 2009-06-19

Abstract: A multielectrode basket-shaped contact catheter (MBC) provides simultaneous recordings of unipolar or bipolar electrograms from within the heart chambers. Another catheter-based mapping approach uses the multielectrode intravenous catheters (MIVCs), which are widely used to diagnose and treat supraventricular arrhythmias. It is also known that mapping techniques are usually limited to one surface at a time. Therefore, an approach that can be used for simultaneous mapping of left and right endocardial surfaces and epicardial surface will be beneficial to characterize and discriminate the endocardial and epicardial sources of the arrhythmias more accurately. In this study, we used statistical estimation method to map the endocardial and epicardial surfaces simultaneously based on combined usage of the MBC and MIVC. The statistical estimation method is based on high-resolution training data set to hypothesize the relationship between catheter measurements and inaccessible sites. To test this approach, we created a high-resolution map database consisting of computer simulation results of Aliev-Panfilov model of cardiac electrical activity on 3-dimensional Auckland canine heart geometry. The simulation database included 2590 maps each paced from a unique endocardial or epicardial site. Fifty or five percent of the database was used as the training data set and the remaining as test data set in the statistical estimation procedure. We selected 64 sites on the left and 64 on the right endocardial surfaces of the model heart geometry and used them as the surrogate MBC measurement sites. Ninety-one sites on the epicardium corresponding to the major coronary veins served as the surrogate MIVC leads. Finally, we tested the success of the method to determine the source of the arrhythmias using the correlation coefficient between the original and estimated activation maps and linear distance between their earliest activated sites. The performance of this approach was promising, such as when MBC on the left endocardium and MIVC were used together, the average linear distance was ∼2.4 mm and mean correlation coefficient was 0.995. It was possible to locate 95% of epicardial arrhythmia cases correctly on the epicardium. Ninety-nine percent of left endocardially originating arrhythmias were correctly located on the left endocardium. The results of this study showed that this approach is feasible and requires further effort.

Articles Appearing in the Next Issue

2010-01-01

Evaluation of the effectiveness of a wearable cardioverter defibrillator detection algorithm

Katie A. Dillon, Steven J. Szymkiewicz, Thomas E. Kaib — 2009-07-01

Abstract: Background: Wearable cardioverter defibrillators (WCDs) provide protection from sudden cardiac death. The efficacy of a WCD detection algorithm has not been reported outside of clinical trial.Methods: The efficacy of the algorithm was reviewed through a retrospective analysis of appropriate shocks, inappropriate shocks, and arrhythmia detections during a 1-year period.Results: WCD patients had an appropriate shock rate of 1.58 per 100 patient-months and an inappropriate shock rate of 0.99 per 100 patient-months. Most of the arrhythmia detections in a 3-month period were short in length, with only 2.7% of the detections lasting over 25 seconds, the time at which a shock becomes possible.Conclusions: By incorporating a patient responsiveness test, as well as features that eliminate or reduce signal interference common to external electrocardiogram electrodes, the WCD detection algorithm has a low risk of inappropriate shocks.

Recurrence of ventricular tachycardia degeneration by low-energy implantable cardioverter-defibrillator shocks: a case report

2009-05-18

Abstract: Despite their proven efficacy at reducing mortality in selected patients, implantable cardioverter-defibrillators have some proarrhythmic effects. In this report, we present a case of a patient with recurrent ventricular tachycardia degeneration to ventricular fibrillation by appropriate low-energy implantable cardioverter-defibrillator shocks.

Delayed cardiac perforation by one small body diameter defibrillator lead

2009-06-11

Abstract: We report a 37-year-old man who presented with continuous chest pain 6 weeks after implantable cardioverter-defibrillator implantation. Implantable cardioverter-defibrillator interrogation indicated complete loss of capture even with maximum output. Chest radiography and echocardiography confirmed extracardiac location of lead tip. After lead repositioning in electrophysiology laboratory, acceptable pacing threshold was obtained with no complication. This report demonstrates a case of delayed cardiac perforation after implantation of the St Jude Medical Durata implantable cardioverter-defibrillator lead.

Local conduction block of the atria by premature stimulus in a patient with Brugada syndrome

2009-08-21

Abstract: A 46-year-old man with type II Brugada electrocardiogram pattern changed to a type I Brugada type electrocardiogram pattern by class I antiarrhythmic drug (pilsicainide) underwent electrophysiologic study. Ventricular fibrillation was induced by double extrastimuli from the right ventricular (RV) apex. Monophasic action potentials (MAPs) were then recorded from the high right atrium. Duration of MAP at a coupling interval of 220 milliseconds was 122 milliseconds, and local activation of S2 spread to the left atrium. However, MAP at a coupling interval of 210 milliseconds was 112 milliseconds, and local activation of S2 failed to spread to the rest of atrium.

Acute occlusion of the left main trunk presenting as ST-elevation acute coronary syndrome

Nazif Aygul, Elvin Salamov, Umuttan Dogan, Mehmet Tokac — 2009-08-21

Abstract: Acute obstruction of the left main coronary artery (LMCA) is not frequently encountered. Electrocardiographic findings are important to early diagnosis in determining an acute obstruction of the LMCA, which requires immediate aggressive treatment, in this extremely unstable condition. However, there is no single typical electrocardiographic pattern representing acute occlusion of the LMCA. We describe a rare electrocardiographic finding that suggested ST-elevation acute coronary syndrome of the anterior zone due to left main trunk total occlusion.

Concomitant left anterior descending coronary artery and right coronary artery occlusion with typical anterior ST depression and inferior ST elevation

2010-01-01

Abstract: We report the case of a 41-year-old man with acute myocardial infarction showing first ST elevation in V1-V6-DI-aVL leads followed by a typical V2-V4 ST depression (concomitant occlusion of proximal diagonal branch with an incomplete left anterior descending occlusion) and DII-DIII-aVF ST elevation. At coronary angiography, a proximal left anterior descending coronary stenosis with right coronary artery thrombosis was found.

Osborn

Laszlo Littmann — 2009-09-27

I enjoyed the interesting electrocardiogram image presented in the September-October issue of the Journal by Drs Hoffmayer and Goldschlager, where apparent “Osborne” waves were caused by dissociated sinus P waves occurring at the end of the junctional QRS complexes. Unfortunately, in this brief presentation, Dr Osborn's name was misspelled 5 times. The cold fact is that his name comes with no “e” at the end; this should be frozen in our minds. Interestingly, you can find the correct spelling of Osborn on page 422 of the same issue, just 1 page ahead of Dr Hoffmayer's and Dr Goldschlager's cool electrocardiogram illustration. We owe Dr Osborn a correct spelling of his name.

Optimum way to evaluate the quality of QT interval measurement in pharmaceutical studies

Marek Malik — 2009-08-10

The evaluation of electrocardiographic (ECG) repolarization signals is used in a number of different applications. These range from the assessment of drug-induced repolarization changes to the identification of cardiac patients at increased arrhythmic risks. Examples of several of such applications have been recently presented in the issue of the journal devoted to the “Mini-symposium on ventricular repolarization indices of VT/VF vulnerability.” Among these, Panicker et al reported on the comparison of threshold and tangent methods for QT interval measurement in ECGs used to evaluate drug-induced QTc prolongation. They based their comparison of the methods on intrasubject and intersubject reproducibility. The suggestions made by Panicker et al have possible implications in other areas where ECGs need to be measured with a guaranteed precision and quality. Therefore, the conclusions proposed by Panicker et al and the methods used in their study might deserve deeper discussion.

Editorial Board

2010-01-01

Journal of Electrocardiology

ECG and VT/VF Symposium

Electrocardiogram screening of infants for long QT syndrome: survey of pediatric cardiologists in North America

QT dynamicity, microvolt T-wave alternans, and heart rate variability during 24-hour ambulatory electrocardiogram monitoring in the healthy newborn of first to fourth day of life

Beat-to-beat interplay of heart rate, ventricular depolarization, and repolarization

Two automatic QT algorithms compared with manual measurement in identification of long QT syndrome

Reference values of electrocardiogram repolarization variables in a healthy population

Ventricular Tachycardia?

Giant Inverted T waves in the emergency department: case report and review of differential diagnoses

Detection of U wave activity in healthy volunteers by high-resolution magnetocardiography

Filtered QRS duration on signal-averaged electrocardiography correlates with ventricular dyssynchrony assessed by tissue Doppler imaging in patients with reduced ventricular ejection fraction

Relationship between T-wave alternans magnitude and the corresponding T-wave height

Simultaneous mapping of endocardium and epicardium from multielectrode intrachamber and intravenous catheters: a computer simulation-based validation

Articles Appearing in the Next Issue

Evaluation of the effectiveness of a wearable cardioverter defibrillator detection algorithm

Recurrence of ventricular tachycardia degeneration by low-energy implantable cardioverter-defibrillator shocks: a case report

Delayed cardiac perforation by one small body diameter defibrillator lead

Local conduction block of the atria by premature stimulus in a patient with Brugada syndrome

Acute occlusion of the left main trunk presenting as ST-elevation acute coronary syndrome

Concomitant left anterior descending coronary artery and right coronary artery occlusion with typical anterior ST depression and inferior ST elevation

Osborn

Optimum way to evaluate the quality of QT interval measurement in pharmaceutical studies

Editorial Board

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