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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 13 (1975), S. 370-381 
    ISSN: 1741-0444
    Keywords: E.C.G. ; Arrhythmia ; Computer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Description / Table of Contents: Sommaire Un nouveau programme d'ordinateur a été mis au point pour extraire les paramètres pertinents de l'électrocardiogramme d'adulte, afin d'interpréter l'arythmie automatique dans le cadre de l'analyse routinière. Aucun programme d'interprétation ne serait acceptable par les cardiologues sans une interprétation de rythme conjuguée à l'interprétation de morphologie, même si, dans une situation de routine, l'interprétation du rythme n'est pas aussi rigoureuse que dans les milieux ambiants du contrôle. Le programme de mesure fonctionne simultanément sur les lignesX, Y etZ du système Frank modifié. Les caractéristiques considérées de l'e.c.g. sont le train d'ondesQRS, les caractéristiques morphologiquesQRS et le train d'ondesP. Bien que le programme fasse toujours l'objet d'une évaluation, plusieurs résultats importants ont été obtenus à partir de l'analyse d'une quantité donnée d'e.c.g. Le mode utilisant la détectionQRS donne une erreur totale de 0,79% par l'addition du nombre de complexesQRS omis et des fausses détections. Le système est apte à réaliser une détection parfaite sur 95% des e.c.g. analysés. La performance sur le classementQRS est de 1,15% des formes d'ondes mal classées, avec un autre taux de 0.67% qui demeure indéfini par suite de la limitation de la capacité de mesure de l'algorithme utilisé; 89·7% des tracés sont complètement exempts d'erreur. L'identification du train d'ondeP est réalisée avec un succès notable. Dans le mode ‘Battement à Battement’, 92·5% des ondesP pour le programme sont présentes dans les tracés pendant la production de 2·2% de phénomènes étrangers.
    Abstract: Zusammenfassung Zum Auszug der entsprechenden Parameter aus den e.k.g.s von Erwachsenen wurde ein neues Rechnerprogramm entwickelt, um automatische Arrhythmien bei der routinemäßigen Untersuchung interpretieren zu können. Ohne Rhythmusinterpretation, die mit der morphologischen Interpretation gekoppelt ist, sollten die Kardiologen keine Interpretations-programme annehmen, selbst wenn die Rhythmusinterpretation bei Routineuntersuchungen nicht so streng ist wie bei der Überwachung. Das Meßprogramm läßt sich gleichzeitig auf denX-,Y- andZ-Abeleitungen des modifizierten Frank-Systems einsetzen. Die berücksichtigten e.k.g.-merkmale sind die WellenserieQRS, die morphologischen WerteQRS und dieP-Wellenserie. Obgleich das Programm noch nicht voll bewertet ist, erhielt man mehrere wichtige Ergebnisse, die auf der Analyse einer bestimmten Anzahl von e.k.g.s beruhen. Bei derQRS-Suche ergibt sich ein Fehler von insgesamt 0·79%, wenn man die Anzahl der ausgelassenenQRS-Komplexe und der falschen Entdeckungen zusammenzählt. Das System kann bei über 95% der analysierten e.k.g.s eine perfekte Entdeckung herbeiführen. Die Leistung bei derQRS-Klassifikation beträgt 1·15% der falsch klassifizierten Wellenformen, mit zusätzlichen 0·67%, die'durch die beschränkte Meßfähigkeit des verwendeten Algorithmus nicht definiert werden. 89·7% der Messungen sind völlig fehlerfrei. Die Identifizierung derP-Wellenserie erreicht man mit weitgehendem Erfolg. Auf der Grundlage von Pulsschlag zu Pulsschlag findet das Programm 92·5% derP-Wellen, während Außeneinwirkungen in Höhe von 2·2% entstehen.
    Notes: Abstract A new computer program has been developed to extract pertinent parameters from the adult e.c.g., for the purpose of automatic arrhythmia interpretation in the context of routine analysis. No interpretation program would be acceptable by cardiologists without a rhythm interpretation coupled to the morphology interpretation even if in routine situations rhythm interpretation is not as stringent as in monitoring environments. The measurements program operates simultaneously on the X, Y and Z leads of the modified Frank system. The e.c.g. features considered are the QRS wavetrain, the QRS morphological characteristics and the P wavetrain. Although the program is still under evaluation, a number of important results have been obtained based on the analysis of a given population of e.c.g.s. The performance on QRS detection gives a total error of 0·79% when adding the number of omitted QRS complexes and false det ections, and the system is able to realise perfect detection on over 95% of the e.c.g.s analysed. The performance on QRS classification is 1·85% of misclassified waveforms, with a further 0·67% which remains undefined due to the limitation in measurement capability of the algorithm used; 89·7% of the tracings are completely error free. The identification of the P wavetrain is achieved with a good degree of success. On a beat-to-beat basis, the program finds 92·5% of the P waves present in the tracings while generating 2·2% extraneous events. However, only 53% of the tracings are error free.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 31 (1993), S. 545-556 
    ISSN: 1741-0444
    Keywords: Cardiac ; Electrical ; Mathematical ; Network ; Retrograde ; and anterograde conduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract A model is proposed to explain mechanisms of propagation in the atrioventricular (AV) node of the heart. The model is based on a simplified twodimensional anatomic description of the central node region and on a bidomain tissue model for the propagation. The central region is described as a three-tissue compartment model: The proximal tissue composed of ANL cells, the central tissue composed of N cells and the distal tissue composed of NH cells. The central N region is outlined as an unexcitable gap by forcing these cells to behave as depressed cells for which the fast ionic currents are inactivated. This model has allowed the authors to test the electrotonic gap hypothesis, which explains the time-delay properties of the AV node. Typical conduction curves have been obtained, as well as common patterns of Wenckebach blocks. Premature stimulus and resulting mapping of cell responses in the N region of the model show typical membrane potential dissociation in two components. The model has also been submitted to several programmed stimulation protocols in documented anterograde and retrograde conduction. The results show that the model is valid and covers several well known dynamic properties of the AV node.
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2009-10-20
    Print ISSN: 0967-3334
    Electronic ISSN: 1361-6579
    Topics: Medicine , Physics
    Published by Institute of Physics
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  • 4
    Publication Date: 2016-03-14
    Print ISSN: 0025-3162
    Electronic ISSN: 1432-1793
    Topics: Biology
    Published by Springer
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  • 5
    Publication Date: 2018-03-05
    Electronic ISSN: 2045-2322
    Topics: Natural Sciences in General
    Published by Springer Nature
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  • 6
    Publication Date: 2015-07-28
    Electronic ISSN: 2045-2322
    Topics: Natural Sciences in General
    Published by Springer Nature
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  • 7
    Publication Date: 2020-12-01
    Description: Theropod dinosaurs are well known for having a ziphodont dentition: serrated, blade-shaped teeth that they used for cutting through prey. Serrations along the carinae of theropod teeth are composed of true denticles, a complex arrangement of dentine, enamel, and interdental folds. This structure would have supported individual denticles and dissipated the stresses associated with feeding. These particular serrations were previously thought to be unique to theropod dinosaurs and some other archosaurs. Here, we identify the same denticles and interdental folds forming the cutting edges in the teeth of a Permian gorgonopsian synapsid, extending the temporal and phylogenetic distribution of this dental morphology. This remarkable instance of convergence not only represents the earliest record of this adaptation to hypercarnivory but also demonstrates that the first iteration of this feature appeared in non-mammalian synapsids. Comparisons of tooth serrations in gorgonopsians with those of earlier synapsids and hypercarnivorous mammals reveal some gorgonopsians acquired a complex tissue arrangement that differed from other synapsids.
    Print ISSN: 1744-9561
    Electronic ISSN: 1744-957X
    Topics: Biology
    Published by The Royal Society
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