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  • 1
    ISSN: 0304-8853
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1433-0474
    Keywords: Schlüsselwörter Linksventrikuläre Tachykardie ; Elektrophysiologische Diagnostik und Therapie ; Key words Leftventricular tachycardia ; Electrophysiological diagnosis and therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary We report about the possibility of electrophysiological diagnosis and therapy in the treatment of a symptomatic left ventricular tachycardia which could not be treated effectively by oral medical therapy in a 10 year old boy with no obvious structural heart disease. By right bundle-bloc-like QRS-complexes in the surface-ECG, the diagnosis of the ventricular origin of the tachycardia was confirmed by transesophageal-ECG. This was followed by the first electrophysiological examination that showed increased leftventricular vulnerability. During this electrophysiological examination the tachycardia was terminated by stimulated singular premature beats. An oral medical therapy with sotalol was started. After the phase of saturation the next ventricular stimulation was done, that showed no sufficient protection of sotalol against VT. So the decision was made for ventricular ablation. After 5 high frequency-applications no furhter ventricular tachycardia could be induced. Since this intervention the patient lives without symptoms
    Notes: Zusammenfassung Wir berichten über die Möglichkeiten der elektrophysiologischen Diagnostik und Therapie in der Behandlung einer medikamentös nicht sicher einstellbaren symptomatischen linksventrikulären Tachykardie bei einem 10jährigen Jungen mit strukturell unauffälligem kardialem Befund. Bei rechtsschenkelblockartig deformierten QRS-Komplexen im Oberflächen-EGK bei der Aufnahme wurde anhand eines anschließend abgeleiteten Ösophagus-EKG die ventrikuläre Genese der Tachykardie bestätigt. Es erfolgte dann eine erste elektrophysiologische Untersuchung, die eine erhöhte linksventrikuläre Vulnerabilität zeigte. Im Rahmen dieser Untersuchung wurde mittels gezielter ventrikulärer Einzelstimulation die Tachykardie terminiert. Anschließend erfolgte eine medikamentöse Einstellung auf Sotalol. Nach der Aufsättigungsphase wurde eine erneute ventrikuläre Stimulation durchgeführt, die keine Schutzwirkung der Sotalolmedikation nachweisen konnte, so daß die Indikation für eine ventrikuläre Katheterablation gestellt wurde. Nach 5 Hochfrequenzapplikationen linksseptal ließ sich keine ventrikuläre Tachykardie mehr induzieren. Der Patient ist im bisherigen Nachbeobachtungszeitraum beschwerdefrei.
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  • 3
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The nonequilibrium Green's function technique is used to derive on the level of a screened Hartree-Fock approximation the nonlinear polarization equation together with the coupled transport equations for spatially inhomogeneous systems in the hydrodynamic regime. With these equations one can calculate the optical spectra of semiconductors with finite geometries for arbitrary light intensities without the use of additional boundary conditions. Furthermore, we derive in the collisionless regime the nonlinear polarization equation for a nonresonantly excited exciton system, which is the basis for the description of the recently observed optical Stark effect.
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  • 4
    ISSN: 1434-6036
    Keywords: 75.30M ; 61.60 ; 78.70D ; 76.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We report on measurements of the lattice constants, magnetic susceptibility, LIII X-ray absorption and Mössbauer-effect on EuNiP and EuPdP, which crystallize in the hexagonal layered Ni2In structure. In both compounds the Eu valence above 510 K is 2.33. With decreasing temperature they show one (EuPdP) or two (EuNiP) first order phase transitions with a valence increase of about 0.16. At the same time thec-axis shrinks while the a-axis even increases. From Mössbauer measurements we show that the nature of the valence mixing is static. In contrast, the valence mixing in isostructural EuPtP is static at low temperatures, too, but it becomes homogeneous valent above a first order phase transition at 235 K. The behaviour of these compounds (as well as that of EuPdAs) is explained in a new model of electrostatically charged layers. In this model we can explain the temperature dependence of the lattice constants, the static valence mixing and the occurrence of preferred valences of the order 2 6/n. Together with the compression shift model of Hirst we can also understand the mechanism of the phase transitions. A comparison with EuT2Si2 compounds in ThCr2Si2 structure shows that in EuTX compounds only the electronic structure of the transition elements is relevant for the occurrence of mixed valency.
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  • 5
    ISSN: 1434-3916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A new technique has been developed to position the cup rigidly into the acetabulum during total hip joint replacement. After positioning the flanged cup on the acetabulum by means of screws, a low-viscosity cement is injected through a hole in the rim of the cup. A comparison with the standard cementing technique was made on the basis of in vitro experiments. For this purpose a mold was constructed to produce castings simulating the human acetabulum. The distribution of the cement, the pressure developed in the acetabulum, and the penetration of the cement are compared for the two cementing techniques.
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  • 6
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The europium valency in hexagonal EuPtP, as examined byL III-x-ray absorption and Moessbauer experiments, is a function of temperature and changes from 2.16 at 295 K to 2.40 at 4 K. In the region of the strongest temperature dependence of the valency, the compound undergoes two first order phase transitions atT 1=235 K andT 2=190 K, characterized by discontinuities in the lattice constants and in the magnetic susceptibility. In the europium Moessbauer spectra, several temperature dependent absorption lines were found, indicating a complex europium valency behaviour. Furthermore, we observe antiferromagnetic order at 8.6 K.
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  • 7
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The resistivity of mixed-valent EuPtP is strongly anomalous and anisotropic with a maximum ratioρ c /ρ ab of about 30. Along thec-axis, the resistivity reaches values up to 600 μΩcm in the temperature range between the two phase transitions near 200 and 240 K, thus approaching the limit for metallic conduction. Characteristics of the voltage-dependent differential resistance of point-contacts between Pt or Mo needles against EuPtP show structures related to the antiferromagnetic order at 8.6 K and the partial ferromagnetic order around 25 K.
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  • 8
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We report three magnetic order transitions, at 25K, 8K and 0.9 K for the ternary intermediate valent europium system EuPtP in addition to the two first order phase transitions, reported in [1]. For comparison Eu0.5Sr0.5PtP was also studied by Lm-X-ray absorption and susceptibility measurements. The two first order transitions do not exist in Eu0.5Sr0.5PtP and only one magnetic order transition was found. The behaviour of EuPtP and Eu0.5Sr0.5PtP is discussed in terms of the domain picture, proposed in [1].
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  • 9
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The intermetallic alloy EuPdAs exhibits a first order phase transition at 180 K. The transition is seen by anomalies in lattice parameters, susceptibility, resistivity, Moessbauer effect and X-ray absorption. It is accompanied by an increase of the Eu valence from 2.15 to 2.40 between 300 K and 4 K. The nature of the non-integral valence and the phase transition are discussed.
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  • 10
    ISSN: 1435-1285
    Keywords: Key words Insulation break – transvenous ICD – oversensing – inadequate shocks ; Schlüsselwörter Sondenisolatorbruch – transvenöser ICD – Fehlsensing – inadäquater Schock
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Angesichts der zunehmenden Komplexität von transvenösen ICD‐Systemen im Vergleich zu herkömmlichen Schrittmachersonden ist mit einer Zunahme von transvenösen Sonderkomplikationen zu rechnen. In dieser Studie wurde die Inzidenz von Isolatordefekten bei transvenösen Sonden bei 130 Patienten während einer Nachtbeobachtungsphase von 23,8 ± 10,9 Monaten ermittelt. Es fand sich eine hohe Inzidenz von 8 Isolatordefekten bei 7 Patienten (8/130 entsprechend 6 %) nach einem mitlleren Sondenalter von 28 ± 13 Monaten, die bei 7 Patienten eine chirurgische Revision nach sich zogen. Nach einer 12monatigen Nachbeobachtungszeit fand sich kein Sondendefekt, nach 24 Monaten waren 96,3 ± 1,8 % aller Sonden intakt, nach 36 Monaten 87,9 ± 6 % und nach 48 Monaten 61,2 ± 18,7 %. Diese Defekte traten ausnahmslos in abdominell implantierten Systemen auf und betrafen immer Silikonsonden desselben Herstellers: 12 % aller verwendeten Endotak®‐Sonden waren betroffen, 19 % auf die ersten Endotak®‐Sondertypen bezogen (60, 62, 64, 70,72, 74). In keinem Fall einer Polyurethansonde vom Typ Transvene® trat ein Isolatordefekt auf. Bei 6 Patienten war der proximale aggregatnahe Abschnitt der Sensingelektroden betroffen. Diese Patienten erlitten alle repetitive Schockabgaben. Bei einem Patienten wurde beim Routine‐ICD‐Wechsel ein Isolatordefekt an der proximalen Schockelektrode gefunden, bei einem weiteren Patienten fand sich der Defekt intravasal zwischen proximaler und distaler Schockelektrode. Trotz regelmäßiger Nachsorge mit Impedanzmessungen waren diese Defekte nur in einem Fall vorhersehbar. Speicherbare intrakardiale Elektrokardiogramme erlaubten eine zuverlässige Diagnose von Sondendefekten, Impedanzmessungen hingegen waren zur sicheren Diagnose von Isolatordefekten nicht geeignet. Mit zunehmendem Sondenalter steht eine Zunahme der Isolatordefekte bei abdominell implantierten ICD mit potentiell gefährlichen inadäquaten Schockabgaben zu befürchten. Insbesondere scheinen ältere Sonden des Typs Endotak 60–74 (s.o.) hiervon betroffen zu sein.
    Notes: Summary With the growing complexity of transvenous ICD‐lead systems the incidence of lead complications might increase in comparison to usual pacemaker leads. The incidence of insulation defects of transvenous leads was determined during a mean follow‐up time of 23.8 ± 10.9 months. Among 130 transvenous ICD‐patients (6 %) could be identified after a mean follow‐up of 28 ± 13 months. After a follow‐up period of 12 months no lead defect was identified, after 24 months 96.3 ± 1.8 % of all transvenous leads were free of complications, after 36 months 87.9 ± 6% and after 48 months in 61.2 ± 18.7 % of all leads no isolator fracture was found. In seven cases an operative revision was required. All insulation‐defects were exclusively found in abdominal implanted silicone lead‐systems type Endotak/CPI (Cardiac Pacemakers, Inc., USA): isolator fractures occurred in 12 % of all Endotak leads used, 19 % of the Endotak C models 62, 64, 72 and 74 were affected. In none of 66 implanted Transvene lead systems (Medtronic, Inc., USA) were isolator defects found. In six patients the proximal part of the sensing lead near the device was affected. All of these patients experienced potentially harmful repetitive device discharges. In one pateint during elective ICD‐replacement an isolation break of the proximal shock electrode was found, in another patient between the proximal and distal shock‐electrode. Despite regular follow‐ups with impedance‐measurements, only in one case was the insulation break foreseeable. Stored electrograms were helpful to disclose insulation defects. With increasing age of the transvenous systems a growing number of insulation defects has to be expected. Especially the isolators of the first Endotak C models 60–74 seem to create major problems with increasing age.
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