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  • Articles: DFG German National Licenses  (2)
  • Garnet  (1)
  • Key words Single-chamber cardioverter/defibrillator – dual-chamber cardioverter/defibrillator – arrhythmia detection – sensitivity – specificity  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Herzschrittmachertherapie & Elektrophysiologie 11 (2000), S. II24 
    ISSN: 1435-1544
    Keywords: Key words Single-chamber cardioverter/defibrillator – dual-chamber cardioverter/defibrillator – arrhythmia detection – sensitivity – specificity ; Schlüsselwörter Einkammer-Kardioverter/Defibrillator – Zweikammer-Kardioverter/Defibrillator – Arrhythmiedetektion – Sensitivität – Spezifität
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung: Eine falsch-positive Erkennung atrialer Tachyarrhythmien als ventrikuläre Rhythmusstörungen mit der Konsequenz elektrischer Therapien stellt auch heute noch ein bedeutsames klinisches Problem in der Therapie mit implantierbaren Kardiovertern/Defibrillatoren dar. Die methodischen Limitationen einer einkanaligen frequenzgebunden Arrhythmiedetektion wurden durch die Einführung ergänzender Arrhythmiedetektionskriterien zu überwinden versucht. Neben den seit Jahren eingeführten, ergänzenden Detektionskriterien wie “Arrhythmiestabilität” und “Arrhythmieonset” wurden zusätzlich Detektionskriterien basierend auf der Morphologieanalyse der endokardialen Elektrogramme in die klinische Therapie mit implantierbaren Defibrillatoren eingeführt. Die Einführung von Zweikammer-Defibrillator-Systemen brachte neben der wichtigen Therapieoption einer physiologischen antibradykarden Stimulation die methodischen Voraussetzungen einer verbesserten Arrhythmiedetektion durch eine simultane Zwei-Kanal-Analyse atrialer und ventrikulärer Signale. In der vorliegenden Übersicht sollen die unterschiedlichen technischen Bedingungen der Arrhythmiedetektion in Einkammer- und Zweikammer-Defibrillatoren unter Einbeziehung der Mehrzahl der klinisch eingeführten ergänzenden Detektionskriterien und Algorithmen kurz zusammenfassend beschrieben werden. Weiter wird versucht eine Übersicht über publizierte Studien und Behandlungsergebnisse zur Sensitivität und Spezifität der Arrhythmiedetektion durch Einkammer und Zweikammer Defibrillatoren darzustellen.
    Notes: Summary False-positive detection of atrial tachyarrhythmias as ventricular arrhythmias, resulting in electrical therapy, is still a major clinical problem in implantable defibrillator therapy. The introduction of enhanced arrhythmia detection parameters tried to overcome the methodical limitations of a single-channel arrhythmia classification. In addition to the enhanced detection parameters, such as “arrhythmia-stability” and “arrhythmia-onset”, introduced several years ago, new additional detection parameters, based on the analysis of intracardiac electrogram morphology, were recently introduced in clinical defibrillator therapy. The introduction of dual-chamber defibrillators provide the important option of physiological antibradycardia pacing and the technical preconditions for an improved arrhythmia classification, based on the simultaneous dual-channel analysis of atrial and ventricular signals. This manuscript will give and an overview of the technical conditions of arrhythmia detection in single and dual-chamber implantable defibrillators with respect to the majority of the clinically used enhanced arrhythmia detection parameters and detection algorithms. Additionally a summary of published studies and clinical results regarding the sensitivity and specificity of arrhythmia detection in single and dual-chamber implantable defibrillator therapy is presented.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0016-7835
    Keywords: Key words Ural ; Maksyutov complex ; Garnet ; Chloritoid ; P ; T path
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Metasedimentary garnet-mica schists are interlayered with metabasic garnet–omphacite schists and enclose eclogite boudins in the high-pressure metamorphic Maksyutov complex in the Southern Urals, Russia. These three rock types were investigated in one outcrop and compared chemographically and thermobarometrically. The Fe/Mg distributions between garnet rim–omphacite and garnet rim–phengite pairs indicate different equilibration temperatures for the three samples, with the lowest temperature (500°C, 〉1.5 GPa) for the eclogite boudin, an intermediate temperature (630°C, 〉1.7 GPa) for the foliated eclogite and the highest temperature (650°C, 〉1.7 GPa) for the garnet-mica schist. The garnets in garnet-mica schist enclose abundant chloritoid relics and the Fe/Mg distribution between chloritoid and garnet records an earlier high-temperature stage (650°C, 〉2.0 GPa) before the garnet rim–phengite temperatures were reached. Together with some minimum- and maximum-pressure estimates three different prograde pressure–temperature paths and a common retrograde metamorphic evolution are interpreted from the chemographic and thermobarometric data. The different early metamorphic evolutions and conditions confirm the variability of protoliths, which are also indicated by different U/Pb zircon and rutile ages.
    Type of Medium: Electronic Resource
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