Traditional Electrocardiogram Research Articles

Introduction to noninvasive cardiac mapping.

From the dawn of the twentieth century, the electrocardiogram (ECG) has revolutionized the way clinical cardiology has been practiced, and it has become the cornerstone of modern medicine today. Driven by clinical and research needs for a more precise understanding of cardiac electrophysiology beyond traditional ECG, inverse solution electrocardiography has been developed, tested, and validated. This article outlines the important progress from ECG development, through more extensive measurement of body surface potentials, and the fundamental leap to solving the inverse problem of electrocardiography, with a focus on mathematical methods and experimental validation.

The value of Duke treadmill score in coronary heart disease

Objective To discuss the value of Duke treadmill score in the diagnosis of coronary heart disease. Methods 94 inpatients underwent treadmill test and coronary angiography, the relationship between the Duke treadmill score and the results of coronary angiography was analyzed. Results The prognostic accuracy and positive predictive value of Duke treadmill score to male and female were 88.9%,85.0%;those of traditional electrocardiogram ST standard were 89.6%,82.5%, the differences were significant(χ2= 4.27,P< 0.05). Conclusion The Duke treadmill score is much more significant than the traditional ST standard in the prognostic accuracy and positive predictive value of diagnosing coronary heart disease. Key words: Treadmill exercise test; Coronary angiography; Duke treadmill score; Coronary heart disease

New ideas for teaching electrocardiogram interpretation and improving classroom teaching content.

BackgroundInterpreting an electrocardiogram (ECG) is not only one of the most important parts of diagnostics but also one of the most difficult areas to teach. Owing to the abstract nature of the basic theoretical knowledge of the ECG, its scattered characteristics, and tedious and difficult-to-remember subject matter, teaching how to interpret ECGs is as difficult for teachers to teach as it is for students to learn. In order to enable medical students to master basic knowledge of ECG interpretation skills in a limited teaching time, we modified the content used for traditional ECG teaching and now propose a new ECG teaching method called the “graphics-sequence memory method.”MethodsA prospective randomized controlled study was designed to measure the actual effectiveness of ECG learning by students. Two hundred students were randomly placed under a traditional teaching group and an innovative teaching group, with 100 participants in each group. The teachers in the traditional teaching group utilized the traditional teaching outline, whereas the teachers in the innovative teaching group received training in line with the proposed teaching method and syllabus. All the students took an examination in the final semester by analyzing 20 ECGs from real clinical cases and submitted their ECG reports.ResultsThe average ECG reading time was 32 minutes for the traditional teaching group and 18 minutes for the innovative teaching group. The average ECG accuracy results were 43% for the traditional teaching group and 77% for the innovative teaching group.ConclusionLearning to accurately interpret ECGs is an important skill in the cardiac discipline, but the ECG’s mechanisms are intricate and the content is scattered. Textbooks tend to make the students feel confused owing to the restrictions of the length and the format of the syllabi, apart from many other limitations. The graphics-sequence memory method was found to be a useful method for ECG teaching.

Intra-QRS spectral changes accompany ST segment changes during episodes of myocardial ischemia

BackgroundCoronary artery disease and myocardial ischemia cause substantial morbidity and mortality. While ischemia is traditionally diagnosed on the 12-lead electrocardiogram (ECG) by shifts in the ST segment, electrical changes are also produced within the QRS complex during depolarization of ischemic ventricular tissue, though these are often of small amplitude and can be missed in traditional ECG analysis. We explore the utility of an easily implemented spectral analysis method for detecting intra-QRS changes during episodes of myocardial ischemia, using Holter recordings from the European ST-T database. MethodsTime-frequency distributions of QRS complexes from each recording were computed using the continuous wavelet transform. Indices corresponding to frequency content of four overlapping frequency bands were computed: F1 (24–35Hz), F2 (30–45Hz), F3 (40–60Hz), and F4 (50–80Hz). Values of these indices were compared during annotated episodes of ST change and during a baseline during the recording. ResultsMarked changes in intra-QRS frequency content were identified during ischemia, grouped by ECG lead analyzed. In lead III, a pronounced and statistically significant increase in the highest frequency sub-bands (F3 and F4) was consistently observed. Analysis of anterior precordial leads also showed significant increases in F4. ConclusionsIntra-QRS time-frequency analysis using the continuous wavelet transform can identify a spectral signature corresponding to myocardial ischemia in the range 24–80Hz. Intra-QRS spectral analysis has the potential for many clinical applications.

12-lead Holter electrocardiography

This brief review is focused on 12-lead Holter electrocardiogram (ECG) recording including a review of the literature and the description of the advantages of its application. The standard 12-lead ECG provides a bedside snapshot of the electrical activity of the heart including vector information, but a snapshot of a few beats for some seconds might miss the whole story. Traditional Holter ECG displaying two or three leads may record all heart beats during a prolonged period, but the limited vector information might be a cause of shortcomings in the ECG diagnosis. The 12-lead Holter ECG overcomes these disadvantages and should be preferred for detecting episodes of arrhythmias, localize their origin or the localization of myocardial ischemia. The 12-lead Holter ECG monitoring is efficient in the evaluation of the effect of drugs or interventional therapeutic procedures, i.e., efficiency of biventricular pacing in patients with heart failure and permanent atrial fibrillation (AF). The automatic analysis of parameters in 12-lead Holter ECG is also providing information for risk stratification. In order to obtain a precise diagnosis based on the criteria established on standard ECG, the "real" 12-lead ECG with ten electrodes is advocated.

Evaluation of a textile-based wearable system for the electrocardiogram monitoring in cardiac patients

We developed a textile-based wearable system, named MagIC, for the unobtrusive monitoring of one electrocardiogram (ECG) lead, respiratory frequency and motion. In the present study, we investigated the ability of this system to monitor cardiac rhythm and arrhythmic events in cardiac patients. The study was carried out by comparing ECG tracings simultaneously recorded by MagIC and traditional ECG devices (Trad-ECG) in 40 cardiac patients at rest and during physical exercise. Data were manually scored by two cardiologists. At rest the artefact rates observed with MagIC and Trad-ECG were virtually identical (1.4% of the registered signal); while during physical exercise the artefact rate observed with MagIC was much lower than with Trad-ECG (4.07 vs. 17.31%). Recordings from MagIC allowed a correct identification of the type of rhythm in the vast majority of patients (92.5%) and an estimation of PQ interval and QRS duration similar to Trad-ECG (<0.016 s). MagIC displayed a good performance in detecting arrhythmias, with only 14 misclassified events out of 3618, and both specificity and sensitivity being above 99%. No practical difference was observed in the estimation of the beat-by-beat RR interval by the two methods. This study indicates that in static condition MagIC has a capability of monitoring cardiac rhythm and arrhythmic events which is comparable with what obtainable by a traditional one-lead ECG recorder. During movement MagIC provides an ECG signal of better quality.

On the validity of using the Polar RS800 heart rate monitor for heart rate variability research

Dear Editor, We read with interest the report of Wallen et al. (2012) concerning the validity of the Polar RS800 heart rate monitor (HRM) as compared to a 5-min supine electrocardiogram (ECG) with respect to the calculation of various indices of heart rate variability (HRV). The Polar system consists of an HRM with bundled software (Polar Pro Trainer 5; PPT) which is used to derive HRV values. Wallen et al. (2012) compare the results from hand-corrected ECG data to this system, and conclude that traditional ECGs should be preferred as ‘‘...the Polar system did not identify errors satisfactorily, or return valid values of HRV for certain groups...’’. It should be noted first that within a research context, inaccuracy of a bundled hardware/software system is somewhat moot. Research groups overwhelmingly utilize the Polar system as a source of RR intervals, which are exported from the PPT software, and corrected if necessary to a normal-to-normal approximation then analysed using separate software. Recent work within this journal, for example, bears this out (e.g., Mateo et al. 2012; Mendonca et al. 2011; Vieira et al. 2012). As Wallen et al. (2012) note, the accuracy of this method is not in question, as previous research (e.g., Weippert et al. 2010) compared the accuracy of ECG-derived and Polar-derived RR intervals and concluded that the RR intervals are sufficiently interchangeable when analysed through identical methods. Wallen et al. (2012) note that recorded RR intervals (as provided from the Polar HRM) are less than ideal for the identification of cardiac dysrhythmia, as a normative ECG waveform is not available. This is undoubtedly the case, but as might be expected from a system designed primarily for tracking HR in a sporting context, the Polar system makes no systematic claims about its ability to identify and eliminate ectopy in groups that may display persistent ectopy at baseline (e.g., the elderly). Thus, the appropriate question is whether Polar-recorded data can optimally produce ECG-comparable measures of HRV, not whether the HRM system is able to identify and deal with cardiac dysrhythmia. Several recent implementations of correction methods applicable to RR series exist (e.g. Barbieri and Brown 2006; Clifford and Tarassenko 2005) but were not attempted by Wallen et al. (2012). The presence and correction of cardiac dysrhythmia (e.g., ectopy, premature atrial contraction) is a well-known source of error in the calculation for HRV, especially in the frequency domain as even one ectopic beat can bias the analysis of a short-term recording (Berntson and Stowell 1998). However, with regard to analytical methods, Wallen et al. (2012) did not provide an explicit methodology for the identification of ectopic beats in their ECG recording beyond visual inspection. The Task Force (1996) paper cited does not specify a methodology beyond stating that interpolation or regression methods may improve the bias conferred by ectopy. The lack of a uniform methodology for the detection of ectopy has the potential for unintended bias in the comparative ECG recording against which the HRM intervals were compared, especially if the assessors are not blind to the overall research question (which was the case in the report by Wallen et al. 2012). Furthermore, Communicated by Susan A. Ward.

Electrocardiography Recordings in Higher Intercostal Space for Children With Right Ventricular Outlet Obstruction Reconstruction Operation

Background and ObjectivesWe checked traditional and high-level precordial electrocardiogram (ECG) leads in patients who had undergone right ventricular outlet obstruction (RVOT) reconstruction surgery and evaluated the effect of ECG lead position on their QRS duration.Subjects and MethodsWe enrolled 34 patients who had undergone surgery for congenital heart disease with RVOT obstruction and who had received followed up care that included recorded ECG at a pediatric cardiac out-patient clinic. The control group included 29 patients who did not have hemodynamically significant intracardiac abnormality. We recorded traditional standard 12-leads ECG from the 4th intercostals space, and moved the precordial leads to the 3rd and 2nd intercostals spaces, and recorded ECGs repeatedly.ResultsIn all groups, there was no significant difference of mean QRS duration and QTc interval between traditional standard 12-leads ECGs and ECGs at higher intercostals spaces. There was no significant difference of ECG parameters between groups. In the control group, the degree of the change between the 4th intercostals space (ICS) QRS and 3rd ICS QRS was significant (p=0.031), and although, it was insignificant, ECGs at the 3rd ICS showed decreased QRS duration in group 1 (V1: 3rd ICS 119.21±21.53 msec vs. 4th ICS 122.80±31.78 msec. V2: 3rd ICS 113.68±19.43 msec vs. 4th ICS 118.24±19.16 msec).ConclusionAlthough the positional change of ECG leads did not result in a significant effect on measuring QRS duration after surgery, ECG leads at the 3rd ICS rather than at the 4th ICS may cause alteration of ECG readings. Therefore, we suggest that ECGs should be recorded in as accurate a position as possible.

Identification of myocardial infarction (MI) using spatio-temporal heart dynamics

Cardiovascular disorders, such as myocardial infarction (MI) are the leading causes of mortality in the world. This paper presents an approach that uses novel spatio-temporal patterns of the vectorcardiogram (VCG) signals for the identification of various types of MI. In contrast to the traditional electrocardiogram (ECG) approaches, the 3D cardiac VCG signal is partitioned into 8 octants for localized analysis of the heart's electrical activities. The proposed method was tested using the PhysioNet PTB database for 368 MIs and 80 healthy control (HC) recordings, each of which includes 12-lead ECG and 3-lead VCG. Significant differences are found in the VCG spatial distribution between MI and HC groups. Furthermore, classification and regression tree (CART) analysis was used to demonstrate that VCG octant features can distinguish MIs from HCs with a sensitivity (accuracy of MI identification) of 97.28% and a specificity (accuracy of HC identification) of 95.00%, which is promising compared to the previously reported results using other ECG databases. The results indicate that the present approach provides an effective way for monitoring, post-processing, and interpretation of ECG data, and hopefully can impact the current cardiac diagnostic practice.

New Trends in Biomedical Signal Processing: A Crossroads Between Smart Sensors in E-Health and Virtual Physiological Human Initiatives

New Trends in Biomedical Signal Processing: A Crossroads Between Smart Sensors in E-Health and Virtual Physiological Human Initiatives

Impact of teaching and assessment format on electrocardiogram interpretation skills

Interpretation of the electrocardiogram (ECG) is a core clinical skill that should be developed in undergraduate medical education. This study assessed whether small-group peer teaching is more effective than lectures in enhancing medical students' ECG interpretation skills. In addition, the impact of assessment format on study outcome was analysed. Two consecutive cohorts of Year 4 medical students (n=335) were randomised to receive either traditional ECG lectures or the same amount of small-group, near-peer teaching during a 6-week cardiorespiratory course. Before and after the course, written assessments of ECG interpretation skills were undertaken. Whereas this final assessment yielded a considerable amount of credit points for students in the first cohort, it was merely formative in nature for the second cohort. An unannounced retention test was applied 8 weeks after the end of the cardiovascular course. A significant advantage of near-peer teaching over lectures (effect size 0.33) was noted only in the second cohort, whereas, in the setting of a summative assessment, both teaching formats appeared to be equally effective. A summative instead of a formative assessment doubled the performance increase (Cohen's d 4.9 versus 2.4), mitigating any difference between teaching formats. Within the second cohort, the significant difference between the two teaching formats was maintained in the retention test (p=0.017). However, in both cohorts, a significant decrease in student performance was detected during the 8 weeks following the cardiovascular course. Assessment format appeared to be more powerful than choice of instructional method in enhancing student learning. The effect observed in the second cohort was masked by an overriding incentive generated by the summative assessment in the first cohort. This masking effect should be considered in studies assessing the effectiveness of different teaching methods.

Invited Commentary

If you have not already heard of the Acute Kidney Injury Network (AKIN), then let this commentary serve as your introduction. AKIN is a large and rapidly growing collaborative organization (www.akinet.org), primarily at this point involving critical care and nephrology societies (the Society of Cardiovascular Anesthesiologists will be the first perioperative organization to join). The goal of AKIN is to advance knowledge that will lead to evidence-based therapies for the treatment and prevention of acute kidney injury (AKI) AKI is the term coined by AKIN to replace “acute renal injury.” This change parallels a strategic approach to AKI investigation similar to “acute myocardial infarction” that has been so successful in improving patient care. AKIN is systematically outlining hurdles to progress—one of the earliest was an absence of a broadly accepted definition for AKI—and they have since proposed the widely accepted AKIN criteria based on creatinine rise or oliguria thresholds, or both. As troponin and creatine kinase-MB fraction have facilitated more timely interventions in the treatment of acute myocardial infarction than the traditional electrocardiogram Q wave, so now is the hope that early AKI biomarkers will revolutionize the field of AKI therapy relative to creatinine rise or dialysis. The article by Haase and colleagues [1Haase M. Bellomo R. Devarajan P. et al.Novel biomarkers early predict the severity of acute kidney injury after cardiac surgery in adults.Ann Thorac Surg. 2009; 88: 124-130Abstract Full Text Full Text PDF PubMed Scopus (157) Google Scholar] nicely summarizes progress in the field of early AKI biomarker development. Although some new tools simply aim to substitute a more ideal creatinine-like substance for estimates of renal filtration (eg, cystatin C), most early markers relate to one of the three early consequences of AKI: tubular cell dysfunction, tubular cell damage, and the adaptive kidney stress response. The hope is that the prompt appearance of biomarkers will facilitate timely AKI risk identification, surveillance (ie, recognition of states such as prerenal azotemia), diagnosis, and prognosis. Strategic approaches such as focused multitest panels may improve the usefulness and precision of AKI biomarkers to address issues such as the timing of onset, grade of problem, and even the type of AKI, such as ischemic vs inflammatory. Preliminary studies indicate that these goals are realistic; however, three caveats are relevant to AKI biomarker development and cardiac surgery. First, there is confusion surrounding the relationship of AKI biomarkers with end organ protection and outcome. We have learned from aprotinin that even when interventions produce favorable changes in hemostasis biomarkers and selected end organ function such as bleeding and transfusion, this should always be followed by trials confirming better overall outcome. Biomarker studies alone are rarely sufficient reason to change practice. Second, oliguria, a criteria for AKI according to AKIN, is likely to prove much less associated with overall adverse outcome perioperatively compared with other settings. Finally, a confusing but apparently benign interaction between lysine analogue antifibrinolytic agents (ie, ε-aminocaproic acid, tranexamic acid) and the proximal renal tubular transport mechanism that causes wasting into the urine of filtered microglobulins and other low-molecular-weight proteins can give a false impression of renal tubular injury. Proteinuria always occurs but also resolves within minutes of discontinuing these drugs. The major hope is that improvements in monitoring with biomarkers will translate into better prevention, treatment, and outcome from AKI, something that has been disappointingly absent during the past half-century since perioperative acute renal failure was first described. Novel Biomarkers Early Predict the Severity of Acute Kidney Injury After Cardiac Surgery in AdultsThe Annals of Thoracic SurgeryVol. 88Issue 1PreviewThe purpose of this study was to investigate the ability of neutrophil gelatinase-associated lipocalin (NGAL), cystatin C, and their combination in predicting the duration and severity of acute kidney injury (AKI) after cardiac surgery in adults. Full-Text PDF

Automated detection of qualitative spatio-temporal features in electrocardiac activation maps

This paper describes a piece of work aiming at the realization of a tool for the automated interpretation of electrocardiac maps. Such maps can capture a number of electrical conduction pathologies, such as arrhytmia, that can be missed by the analysis of traditional electrocardiograms. But, their introduction into the clinical practice is still far away as their interpretation requires skills that belongs to very few experts. Then, an automated interpretation tool would bridge the gap between the established research outcome and clinical practice with a consequent great impact on health care. Qualitative spatial reasoning can play a crucial role in the identification of spatio-temporal patterns and salient features that characterize the heart electrical activity. We adopted the spatial aggregation (SA) conceptual framework and an interplay of numerical and qualitative information to extract features from epicardial maps, and to make them available for reasoning tasks. Our focus is on epicardial activation isochrone maps as they are a synthetic representation of spatio-temporal aspects of the propagation of the electrical excitation. We provide a computational SA-based methodology to extract, from 3D epicardial data gathered over time, (1) the excitation wavefront structure, and (2) the salient features that characterize wavefront propagation and visually correspond to specific geometric objects. The proposed methodology provides a robust and efficient way to identify salient pieces of information in activation time maps. The hierarchical structure of the abstracted geometric objects, crucial in capturing the prominent information, facilitates the definition of general rules necessary to infer the correlation between pathophysiological patterns and wavefront structure and propagation.

Handheld electrocardiogram measurement instrument using a new peak quantification method algorithm built on a system-on-chip embedded system

This article reports on the new design and development of an electrocardiogram (ECG) measurement instrument built on a system-on-chip (SOC) embedded system. A new approach using the peak quantification method (PQM) for measuring the human heart rate is described. A computer, some medical equipment, and other facilities are often required for conducting the traditional ECG measurements. However, the monitors of such instruments have some disadvantages, e.g., bulky, not very easy to transport, expensive, and so forth. Hence, we propose a new design for ECG measurement which is built on an embedded system. Our system adopts a SOC and ECG detection circuits to carry out a real-time, low-cost, and compact ECG measurement system. Regarding heart rate computation, the experimental results show that the new PQM algorithm, when applied to heart rate measurements, yields error smaller than 1bpm. In addition, the correlation coefficient between the measured and actual heartbeats can reach 0.94 when the heart rate is less than 153bpm. It shows that the use of the PQM algorithm gives an extremely high degree of accuracy.

Magnetocardiograms in Clinical Medicine: Unique Information on Cardiac Ischemia, Arrhythmias, and Fetal Diagnosis

Cardiac diseases are the leading cause of death in population. Diagnostic tests to detect cardiac dysfunction at an early stage of the disease are desirable. The major focus has been centered on tests evaluating the perfusion of the heart with imaging techniques or detecting alterations in electrical or mechanical function of the heart. The heart generates magnetic fields that can be detected by body surface mapping utilizing super conducting quantum interference device sensors giving magnetocardiograms (MCGs). The advantages of MCG over traditional electrocardiograms (ECGs) are increased sensitivity to small signals and lack of conductivity in body tissues, presentation of direct component signals and primary currents. This review will highlight the basic principles and recent advantages of MCGs, and the application of MCG in clinical diagnosis, especially in cases whose ECGs are non-diagnostic or not specific, such as detecting baseline shift in ischemic heart disease, noninvasive His potential recording, detection of arrhythmic mechanism defining reentrant circuits vs non reentrant mechanism, diagnosis of fetal arrhythmias and prolongation of QT interval. Areas of future basic and clinical research are also discussed.

Setting a New Gold Standard

Setting a New Gold Standard

A rate distortion optimal ECG coding algorithm.

Signal compression is an important problem encountered in many applications. Various techniques have been proposed over the years for addressing the problem. In this paper, we present a time domain algorithm based on the coding of line segments which are used to approximate the signal. These segments are fit in a way that is optimal in the rate distortion sense. Although the approach is applicable to any type of signal, we focus, in this paper, on the compression of electrocardiogram (ECG) signals. ECG signal compression has traditionally been tackled by heuristic approaches. However, it has been demonstrated [1] that exact optimization algorithms outperform these heuristic approaches by a wide margin with respect to reconstruction error. By formulating the compression problem as a graph theory problem, known optimization theory can be applied in order to yield optimal compression. In this paper, we present an algorithm that will guarantee the smallest possible distortion among all methods applying linear interpolation given an upper bound on the available number of bits. Using a varied signal test set, extensive coding experiments are presented. We compare the results from our coding method to traditional time domain ECG compression methods, as well as, to more recently developed frequency domain methods. Evaluation is based both on percentage root-mean-square difference (PRD) performance measure and visual inspection of the reconstructed signals. The results demonstrate that the exact optimization methods have superior performance compared to both traditional ECG compression methods and the frequency domain methods.