Search

Introduction. False alarm reduction is an important challenge in self-care, whereas one of the most important false alarm causes in the cardiology domain is electrodes misplacements in ECG recordings, the main investigations to perform for early and pervasive detection of cardiovascular diseases. In this context, we present and assess a new method for electrode reversals identification for Mason-Likar based 3D ECG recording systems which are especially convenient to use in self-care and allow to achieve, as previously reported, high computerized ischemia detection accuracy. Methods. We mathematically simulate the effect of the six pairwise reversals of the LA, RA, LL, and C2 electrodes on the three ECG leads I, II, and V2. Our approach then consists in performing serial comparisons of the newly recorded 3D ECG and of the six derived ECGs simulating an electrode reversal with a standard, 12-lead reference ECG by means of the CAVIAR software. We further use a scoring method to compare these analysis results and then apply a decision tree model to extract the most relevant measurements in a learning set of 121 patients recorded in ICU. Results. The comparison of the seven sets of serial analysis results from the learning set resulted in the determination of a composite criteria involving four measurements of spatial orientation changes of QRS and T and providing a reversal identification accuracy of 100%. Almost the same results, with 99.99% of sensitivity and 100% of specificity, were obtained in two test sets from 90 patients, composed of 2098 and 2036 representative ECG beats respectively recorded during PTCA balloon inflation, a procedure which mimics ischemia, and before PTCA for control. Conclusion. Personalized automatic detection of ECG electrode cable interchanges can reach almost the maximal accuracy of 100% in self-care, and can be performed in almost real time.

The possibility to remotely use powerful computerized ECG analysis methods at any time is of utmost importance for the early detection of cardiovascular diseases. We present an ECG web services portal that allows to use on request our serial and unary ECG processing methods, CA VIAR and/or the Lyon program. After authentication, the user can upload digital ECG signal data encoded according to SCP-ECG or in a specific ASCII format. The Lyon program (re-)analyses the ECGs and provides SCP-ECG files containing a typical beat, wave onsets and offsets, and a downloadable table of standard ECG measurements. The CAVIAR web service provides a downloadable table of serial measurements and interactive 3D graphical representations of spatiotemporal QRS and T changes between the typical/median beats of the uploaded ECG records or between the uploaded beats, after their optimized superimposition. As a result, precise measures of ECG changes in amplitude, orientation and duration (QRS, QT…) are obtained, after correction for wave delineation errors by means of spatiotemporal resynchronization of the compared beats. User-defined or automated comparisons with a reference ECG and/or with the earliest or the previous one can be performed. 3D graphic plots of the superimposed QRS and T pairs are displayed in 1, 2, 4, 6 or 9 panels/page. The user can then rotate each plot, or all plots simultaneously, in any 3D direction, to highlight relevant spatiotemporal changes. We present the various functionalities of our FR-ECG web portal http://FR-ECG.univ-lyon1.fr and some results.

Introduction Ventricular arrhythmias in Brugada syndrome (BrS) may be due to a combination of myocardial depolarization and repolarization abnormalities. The spatial QRS-T angle, measured by 3D ECG, reflects both myocardial depolarization and repolarization and has been proposed as a marker for sudden cardiac death risk in several cardiomyopathies. This marker has never been evaluated in BrS patients. Objective To evaluate the prognostic significance of the spatial QRS-T angle in patients with a spontaneous Brugada type 1 pattern (SBT1). Method 8 patients with a SBT1 were included (8 males, mean age 49.1 ± 10.9 years-old), 4 experienced sudden cardiac arrest or documented ventricular fibrillation (SCA/VF) at mean age of 38.8 ± 14.3 years-old. We analyzed conventional ECG and 3D ECG data using the CAVIAR method and compared data from VF/SCA group to other subjects. Results The spatial angle between the onset of the QRS and the T-wave loop (ODIR angle) was significantly higher in the SCA/VF group (49.1 ± 26.0 vs. 19.8 ± 3.8, P = 0.029). There was no significant difference between patients for conventional ECG measurements (PR interval 187.0 ± 29.6 ms in the SCA/VF group vs. 186.0 ± 38.7 ms, P = 1, QRS duration 130.0 ± 38.7 ms vs. 106.5 ± 12.5 ms, P = 0.30, corrected QT interval 471.8 ± 8.4 ms vs. 404.3 ± 45.1 ms, P = 0.057, Tpeak–Tend interval 115.5 ± 3.8 ms vs. 107.5 ± 34.7 ms, P = 1) ( Fig. 1 ). Conclusion The spatial angle between the onset of QRS and the T-wave loop appears to be significantly correlated with the risk of VF/SCD in BrS patients. A prospective study is needed to confirm these findings.

The objective of this research work is to empower healthcare information systems to deliver high quality information anytime and anywhere and to present distributed and heterogeneous resources access solutions which perfectly meet user requirements in different contexts. To reach this objective, we propose in this paper a new framework, called ONtology Oriented Framework for Pervasive Applications and Services (ONOF-PAS), and mainly based on: 1) interrelated ontological models representing the main entities in pervasive computing, such as Organization, Actor, Task, Service, Process, Object, Resources, etc.; 2) rule-based reasoning to infer the available and capable resources required by each task. The main functionality of the ONOF-PAS framework is to capture and to process the acquired knowledge about the user's context, the tasks they perform, the availability and capabilities of the required resources, and the organizations that own or manage these resources. Our framework allows healthcare information systems to infer the needed resources by linking each user-task with the required, available and capable resources taking into account the clinical conditions of the patients. The ONOF-PAS framework has been successfully applied in the telemedicine domain in order to provide practical and efficient resources access solutions that better meet the contexts and the expectations of the eHealth actors.

The main goal of the SCP-ECG standard is to address ECG data and related metadata structuring, semantics and syntax, with the objective of facilitating interoperability and thus supporting and promoting the exchange of the relevant information for unary and serial ECG diagnosis. Starting with version V3.0, the standard now also provides support for the storage of continuous, long-term ECG recordings and affords a repository for selected ECG sequences and the related metadata to accommodate stress tests, drug trials and protocol-based ECG recordings. The global and per-lead measurements sections have been extended and three new sections have been introduced for storing beat-by-beat and/or spike-by-spike measurements and annotations. The used terminology and the provided measurements and annotations have been harmonized with the ISO/IEEE 11073-10102 Annotated ECG standard. Emphasis has also been put on harmonizing the Universal Statement Codes with the CDISC and the categorized AHA statement codes and similarly the drug and implanted devices codes with the ATC and NASPE/BPEG codes.

Synthesis of the 12-lead ECG has been investigated in the past decade as a method to improve patient monitoring in situations where the acquisition of the 12-lead ECG is cumbersome and time consuming. This paper presents and assesses a novel approach for deriving 12-lead ECGs from a pseudoorthogonal three-lead subset via generic and patient-specific nonlinear reconstruction methods based on the use of artificial neural-networks (ANNs) committees. We train and test the ANN on a set of serial ECGs from 120 cardiac inpatients from the intensive care unit of the Cardiology Hospital of Lyon. We then assess the similarity between the synthesized ECGs and the original ECGs at the quantitative level in comparison with generic and patient-specific multiple-regression-based methods. The ANN achieved accurate reconstruction of the 12-lead ECGs of the study population using both generic and patient-specific ANN transforms, showing significant improvements over generic (p -valueor = 0.05) and patient-specific ( p-valueor = 0.01) multiple-linear-regression-based models. Consequently, our neural-network-based approach has proven to be sufficiently accurate to be deployed in home care as well as in ambulatory situations to synthesize a standard 12-lead ECG from a reduced lead-set ECG recording.

Recent years have witnessed a growing interest in developing personalized and nonhospital based care systems to improve the management of cardiac care. The EPI-MEDICS project has designed an intelligent, portable Personal ECG Monitor (PEM) embedding an advanced decision making system. We present two of the ambient intelligence models embedded in the PEM: the neural-network based ischemia detection module and the Bayesian-network risk stratification module. Ischemia detection was expanded to take into account the patient ECG, clinical data, and medical history. The neural-network ECG interpretation module and the Bayesian-network risk factors module collaborate through a fuzzy-logic-based layer. We also present two telemedicine solutions that we have designed and in which the PEM is integrated. The first telemedical architecture was created to allow the collection of medical data and their transmission between healthcare providers to get an expert opinion. The second one is intended for improving healthcare in old people’s homes.

Software-defined radios (SDRs) are now recognized as a key building block for future wireless communications. We have spent the past year enhancing existing open software to create a software-defined data radio. This radio extends the notion of software-defined behavior to higher layers in the protocol stack: most importantly through the media access layer. Our particular approach to the problem has been guided by the desire to allow fine-grained cognitive control of the radio. We describe our system, Adaptive Dynamic Radio Open-source Intelligent Team (ADROIT).

Background The standard 12-lead ECG remains one of the basic investigations for the early detection and assessment of acute coronary syndromes. It is easy to perform, anywhere and anytime, and can be digitally transmitted within minutes to an emergency medical service for remote advice and triage. But the conventional ST-segment deviation criteria are of limited diagnostic accuracy. The purpose of this study is to investigate how much the use of computerized ECG techniques based on the measurement of the serial spatiotemporal ECG changes could improve the detection accuracy of transmural myocardial ischemia. Methods We considered the serial changes of continuous 12-lead ECGs of 90 patients undergoing elective percutaneous coronary angioplasty (PTCA) recorded during balloon inflation as an experimental model of ECG changes induced by coronary artery occlusion. The spatiotemporal ECG changes were measured according to the CAVIAR method and assessed by multivariate discriminant analysis in reference to serial changes of control recordings and standard ECG criteria. Results The diagnostic accuracy of the CAVIAR criteria for ischemia detection was 97%, with sensitivity of 98% and specificity of 96%, whereas the diagnostic accuracy of the conventional ST-segment criteria was 74%, with sensitivity of 60% and specificity of 88%. The increase of overall performance was obtained for all the occlusion locations. Conclusions Computer-assisted quantitative serial ECG analysis, taking into account the spatiotemporal changes of the QRS and T waves, would provide the physician with additional information for significantly improving the detection of transmural myocardial ischemia.

Background and Purpose If only a standard electrocardiogram (ECG) is available, at least 25% of patients with long QT syndrome (LQTS) may be missed. Our goal is to quantify abnormal electrical activity and to develop an ECG decision rule for the patients with LQTS. Methods One hundred forty-one subjects were included in this study (71 patients with LQTS and 70 healthy subjects). A 12-lead digital ECG was recorded for each subject and analyzed using the CAVIAR (comparative analysis of ECG-VCG and their interpretation with auto-reference to the patient) method. Results A decision tree involving criteria based on 3 spatiotemporal ECG measurements—the QT interval and the maximum amplitude of the T wave, both corrected from heart rate, and the loss of planarity of the end of QRS—identified patients with LQTS from healthy subjects with a sensitivity of 89%, a specificity of 96%, and a total accuracy of 92%. Conclusions This study suggests that 3-dimensional ECG analysis may improve the detection of patients with LQTS.

Aim We sought to determine whether survivors of sudden death without structural heart disease have beat-to-beat electrocardiographic (ECG) characteristics at the microvolt and at the millisecond level that differ from normal subjects. Methods We studied patients at our implantable cardioverter defibrillator clinic who had been resuscitated from ventricular fibrillation with no evidence of underlying structural heart disease. Continuous 10-minute high-resolution unfiltered digital surface ECGs at 1000-Hz sampling rate were acquired in these subjects and in a group of healthy volunteers. We then analyzed different parameters of beat-to-beat variations in duration, amplitudes and vectors of the QRS complex, and the T wave using a locally developed program (Comparative Analysis of ECGs, Vectocardiograms, and their Interpretation with Auto-Reference to the patient) and compared them between the 2 groups. Results Thirteen patients (7 men; age, 46 ± 16 years) were studied. Standard ECGs were unremarkable in 7 patients and suggestive of Brugada syndrome in the 6 others. The control group consisted of 23 age- and sex-matched subjects (13 men; age, 41 ± 10 years). Although the QRS parameters showed only few differences between the 2 groups, there were several differences in parameters evaluating repolarization. Conclusion High-resolution ECGs show distinct beat-to-beat variations in parameters of repolarization in survivors of sudden death without structural heart disease, as compared with normal subjects. These findings may reflect increased electrical instability and should be evaluated for stratifying arrhythmic risk in asymptomatic individuals.

Applications that are part of a mission-critical information system need to maintain a usable level of key services through ongoing cyber-attacks. In addition to the well-publicized denial of service (DoS) attacks, these networked and distributed applications are increasingly threatened by sophisticated attacks that attempt to corrupt system components and violate service integrity. While various approaches have been explored to deal with DoS attacks, corruption-inducing attacks remain largely unaddressed. We have developed a collection of mechanisms based on redundancy, Byzantine fault tolerance, and adaptive middleware that help distributed, object-based applications tolerate corruption-inducing attacks. In this paper, we present the ITUA architecture, which integrates these mechanisms in a framework for auto-adaptive intrusion-tolerant systems, and we describe our experience in using the technology to defend a critical application that is part of a larger avionics system as an example. We also motivate the adaptive responses that are key to intrusion tolerance, and explain the use of the ITUA architecture to support them in an architectural framework. Copyright © 2006 John Wiley & Sons, Ltd.

Despite many attempts to improve the management of acute myocardial infarction, only small trends to shorter time intervals before treatment have been reported. The self-care solution developed by the European EPI-MEDICS project (2001-2004) is a novel, very affordable, easy-to-use, portable, and intelligent Personal ECG Monitor (PEM) for the early detection of cardiac ischemia and arrhythmia that is able to record a professional-quality, 3-lead electrocardiogram (ECG) based on leads I, II, and V2; derive the missing leads of the standard 12-lead ECG (thanks to either a generic or a patient-specific transform), compare each ECG with a reference ECG by means of advanced neural network-based decision-making methods taking into account the serial ECG measurements and the patient risk factors and clinical data; and generate different levels of alarms and forward the alarm messages with the recorded ECGs and the patient's Personal electronic Health Record (PHR) to the relevant health care providers by means of a standard Bluetooth-enabled, GSM/GPRS-compatible mobile phone. The ECG records are SCP-ECG encoded and stored with the PHR on a secure personal SD Card embedded in the PEM device. The alarm messages and the PHR are XML encoded. Major alarm messages are automatically transmitted to the nearest emergency call center. Medium or minor alarms are sent on demand to a central PEM Alarm Web Server. Health professionals are informed by a Short Message Service. The PEM embeds itself a Web server to facilitate the reviewing and/or update of the PHR during a routine visit at the office of the general physician or cardiologist. Eighty PEM prototypes have been finalized and tested for several weeks on 697 citizens/patients in different clinical and self-care situations involving end users (188 patients), general physicians (10), and cardiologists (9). The clinical evaluation indicates that the EPI-MEDICS concept may save lives and is very valuable for prehospitalization triage.

In the current issue of the Journal, Klatsky et al (1) address the possible risk of chronically having “normal” electrocardiographic (ECG) changes that may mimic the presence of an acute myocardial infarction. The authors compare the rates of hospital admissions for various conditions, and outpatient cardiovascular diagnoses, in patients with early repolarization and controls. The presence of “normal” early repolarization changes on the ECG could indeed be misinterpreted as signs of an acute thrombotic occlusion of a coronary artery, and lead to inappropriate and even potentially harmful reperfusion therapy. Of the many people who present for emergency clinical evaluation with symptoms suggesting an acute coronary syndrome, only a small proportion have the thrombotic coronary occlusion for which immediate reperfusion therapy is indicated. The current European Society of Cardiology/American College of Cardiology guidelines suggest immediate reperfusion therapy only in patients with “ST elevation or presumably new left bundle branch block” (2). However, since ST elevation in the absence of myocardial infarction is common, the diagnostic threshold for such therapy yields low specificity. In the current paper, 30% of the subjects chronically had ST elevations 3 mm. Other studies (3,4) also indicate that ST elevation above the commonly accepted threshold is not unusual, particularly in young men. Thus an individual’s age and gender should also be considered. Both female gender and older age are associated with lower amplitudes of all ECG waveforms, including the ST segment (3). The phenomenon associated with “normal” ST elevation has been termed “early repolarization” and pertains to the absence of a truly isoelectric ST segment between the QRS complex of ventricular depolarization and the T wave of repolarization. The prevalence of early repolarization may be increased when the ST-segment changes are measured late after the J point, the heart rate is accelerated or there are conditions such as left ventricular hypertrophy or fascicular or bundle branch block that prolong the ventricular depolarization process (3). The findings by Klatsky et al (1) support previous reports of a high prevalence of early repolarization in young men of African descent (5– 8), and in persons who engage regularly in “vigorous” exercise (9,10). These findings also support the benign prognosis of this condition and even show nonsignificant trends toward lower use of health care. However, this study does not provide direct information on whether inappropriate and unnecessary therapy was administered as a result of misinterpretation of the early repolarization changes in patients who were admitted for in-hospital care. Because ST elevation due to early repolarization may be interpreted as changes due to myocardial infarction, several noninvasive and practical approaches can be taken to minimize misinterpretation. This editorial considers the use of new algorithms for computerized analysis of an individual ECG; observations of the “stability” of the ST-segment changes on serial ECGs; and other nonECG manifestations of ischemia, such as regional wall motion abnormalities assessed by echocardiography and myocardial perfusion defects via radionuclide measurements or contrast echocardiography.

Introduction: The aim of this study was to determine whether impaired adaptation of the QT interval to changes in heart rate predicts sudden death after an acute myocardial infarction. Methods and Results: The Groupe d'Etude du Pronostic de l'Infarctus du Myocarde (GREPI) trial was a prospective multicenter study designed to evaluate the long-term outcome of myocardial infarction. QT dynamicity was evaluated in 265 patients by analyzing 24-hour Holter recordings obtained 9 to 14 days after myocardial infarction. The linear regression slope of QT intervals measured to the apex and to the end of the T wave (QTe) plotted against RR intervals was calculated using a dedicated Holter algorithm. The value of QT/RR in predicting sudden death and total mortality was compared with those of ejection fraction, heart rate variability, and late potentials. Mean follow-up was 81 ± 27 months. There were 73 deaths, of which 23 were sudden. Of all the parameters, an increased diurnal QTe/RR slope (>0.18) was the strongest independent predictor of sudden death (relative risk 6.07, confidence interval 1.48–24.95,P = 0.01). Conclusion: Increased diurnal QTe dynamicity is independently predictive of sudden death among patients with myocardial infarction. This simple parameter may help to stratify risk and select patients who may benefit from antiarrhythmic prophylaxis.(J Cardiovasc Electrophysiol, Vol. 14, pp. 227-233, March 2003)