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  • 1
    Electronic Resource
    Electronic Resource
    Defects in epitaxial Si-doped GaInP (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 260-266 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have characterized by capacitance-voltage and deep level transient spectroscopy measurements the only defect detected in Si-doped GaInP layers. This defect exhibits an ionization energy of 0.435 eV but is located only at ∼20 meV below the bottom of the conduction band. All its characteristics, i.e., energy level, apparent capture barrier, ionization energy, can be understood if the defect is a donor associated DX center. Its cross section for electron and hole capture have been measured. The effect of an electric field on the ionization energy confirms that the defect is indeed shallow and a donor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354156
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  • 2
    Electronic Resource
    Electronic Resource
    Increased Activation of L-Type Voltage-Dependent Calcium Channels Is Associated with Glycine Enhancement of N-Methyl-d-Aspartate-Stimulated Dopamine Release in Global Cerebral Ischemia/Reperfusion (1994)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 63 (1994), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: We investigated the relationships among N-methyl-d-aspartate, glycine, L-type voltage-dependent calcium channels, and [3H]dopamine release in a canine model of global cerebral ischemia/reperfusion. The binding of [3H]PN200-110 ([3H]isradipine) to L-type voltage-dependent calcium channels, that open as a consequence of N-methyl-d-aspartate-induced changes in membrane potential, was approximately doubled in striatal membranes prepared from ischemic animals relative to controls, and remained significantly elevated at 30 min and 2 h of reperfusion. These changes coincided temporally with changes in the ability of the voltage-sensitive calcium channel blocker nitrendipine to inhibit glycine enhancement of N-methyl-d-aspartate-stimulated [3H]dopamine release in striatal slices prepared from the same animals. Compared with nonischemic controls, N-methyl-d-aspartate-stimulated [3H]dopamine release was increased in ischemic animals and remained increased throughout reperfusion up to at least 24 h. Glycine enhanced N-methyl-d-aspartate-stimulated release in all treatment groups. The enhancement of N-methyl-d-aspartate-stimulated dopamine release by glycine was reduced by the inclusion of nitrendipine in striatal slices from ischemic and 30-min reperfused animals. These data suggest that glycine may facilitate opening of the voltage-dependent calcium channels activated by N-methyl-d-aspartate and that this facilitation is blocked by the antagonist nitrendipine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1994.63010215.x
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  • 3
    Electronic Resource
    Electronic Resource
    Electrophysiologic Spectrum of Atrioventricular Nodal Behavior in Patients with Atrioventricular Nodal Reentrant Tachycardia Undergoing Selective Fast or Slow Pathway Ablation (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cardiovascular electrophysiology 4 (1993), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: AV Nodal Behavior After Ablation. Introduction; The objective of this report is to delineate the atrioventricular (AV) nodal electrophysiologic behavior in patients undergoing fast or slow pathway ablation for control of their AV nodal reentrant tachycardia (AVNRT). Methods and Results: One hundred sixteen consecutive patients with symptomatic AVNRT were included. Twenty-two patients underwent fast pathway ablation with complete abolition of AVNRT in all and development of complete AV block in five patients. Of 17 patients with intact AV conduction postablation, 12 had demonstrated antegrade dual pathway physiology during baseline study, which was maintained in three and lost in nine patients postablation. Two patients with successful fast pathway ablation developed uncommon AVNRT necessitating a slow pathway ablation. Twenty-one patients demonstrated both common and uncommon forms of AV nodal reentry during baseline study. The earliest site of atrial activation was close to the His-bundle recording site (anterior interatrial septum) during common variety and the coronary sinus ostium (posterior interatrial septum) during the uncommon AV nodal reentry in all 21 patients. Ninety-six patients underwent successful slow pathway ablation. Among these, the antegrade dual pathway physiology demonstrable during baseline study (60 patients) was maintained in 25 and lost in 35 patients postablation. Conclusion: These data suggest that: (1) dual pathway physiology may persist after successful ablation, which might be a reflection of multiple reentrant pathways in patients with AVNRT: and (2) the retrograde pathways during common and uncommon AVNRT have anatomically separate atrial breakthroughs. These findings have important electrophysiologic implications regarding the prevailing concept of the AV nodal physiology in patients with AVNRT.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8167.1993.tb01216.x
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  • 4
    Electronic Resource
    Electronic Resource
    Optimization of Shocking Lead Configuration for Transvenous Atrial Defibrillation (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cardiovascular electrophysiology 9 (1998), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Optimum Electrodes for Atrial Defibrillation. Introduction: High atrial defibrillation energy requirements (ADER) in patients with chronic atrial fibrillation (AF) may limit the acceptance of transvenous atrial defibrillation. We evaluated an optimized defibrillation electrode configuration that could help to reduce the ADKR in patients with AF. Methods and Results: We tested ten different configurations in nine dogs with AF (3.33 ± 2.92 days) induced by rapid atrial pacing. The configurations were: right atrial (RA) appendage as anode und coronary sinus (CS) as cathode; RA and innominate vein (I) as anode to CS (cathode); RA-CS (anode) to I (cathode); I-CS (anode) to RA (cathode); RA and left lateral subcutaneous patch (P) as anode to CS (cathode); RA-CS (anode) to P (cathode); P-CS (anode) to RA (cathode); superior vena cava (SVC) and CS (anode) to RA (cathode); RA-CS (anode) to SVC (cathode); and RA-SVC (anode) to CS (cathode). ADER was defined as the voltage needed to defibrillate the atria in 10% to 90% of 20 consecutive shocks. Three lead systems had ADER lower than the RA (anode) to CS (cathode) configuration, which required a mean of 143 ± 58 volts. These three were: RA-SVC (anode) to CS (cathode) 103 ± 29 V; I-CS (anode) to RA (cathode) 129 ± 39 V; and P-CS (anode) to RA (cathode) 130 ± 38 V. The remaining configurations had ADER higher than the RA (anode) to CS (cathode) configuration. Conclusion: Adding an additional shocking electrode may reduce ADER when compared with the RA (anode) to CS (cathode) configuration. This concept could he incorporated into future implantable atrial defibrillators or used for refractory patients undergoing temporary transvenous cardioversion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8167.1998.tb00141.x
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  • 5
    Electronic Resource
    Electronic Resource
    Catheter Ablation in Supraventricular Tachyarrhythmias (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of interventional cardiology 8 (1995), S. 0 
    Details
    ISSN: 1540-8183
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8183.1995.tb00515.x
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  • 6
    Electronic Resource
    Electronic Resource
    Bundle Branch Reentrant Ventricular Tachycardia: (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cardiovascular electrophysiology 4 (1993), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Sustained Bundle Branch Reentrant Tachycardia. introduction: The clinical, electrophysiologic features and follow-up of 48 patients with inducible bundle branch reentrant (BBR) tachycardia are presented. Methods and Results: Forty-eight patients were identified in whom a diagnosis of BBR tachycardia was made during electrophysiologic evaluation. The clinical presentation was syncope or sudden death in 38 patients, and sustained palpitations during wide QRS complex tachycardia in 5 patients. Electrophysiologic studies were performed in 5 additional patients for various other reasons. Structural heart disease was present in 45 patients. Idiopathic dilated cardiomyopathy and coronary artery disease were the anatomical substrates in 19 (39%) and 24 (50%) patients, respectively, severe aortic regurgitation was present in 2 patients, and no organic heart disease was identified in 3. All 48 patients had evidence of His-Purkinje system disease. BBR tachycardia with left and right bundle branch block morphologies was induced in 46 and 5 patients, respectively, and interfascicular BBR tachycardia was initiated in 2 patients. Ventricular tachycardia of a myocardial origin was induced in 11 patients. Management of BBR tachycardia included transcatheter bundle branch ablation in 28 patients, and antiarrhythmic drug therapy in 16 patients. Four patients were treated with implantablc defibrillators. After a mean follow-up of 15.8 months in 42 patients, there were 13 deaths due to congestive heart failure, 4 sudden cardiac deaths, 3 nonsudden cardiac deaths, and 3 noncardiac related deaths. Conclusion: Sustained BBR, a form of monomorphic ventricular tachycardia, is a highly malignant arrhythmia usually seen in patients with structural heart disease. Three different types of BBR tachycardia are described. If distinguished from ventricular tachycardia of a myocardial origin, catheter ablation of the right bundle branch can be easily performed and effectively eliminates BBR. During follow-up, congestive heart failure is the most common cause of death in this population.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8167.1993.tb01228.x
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  • 7
    Electronic Resource
    Electronic Resource
    Sinus Tachycardia with Atrioventricular Block: (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cardiovascular electrophysiology 9 (1998), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Sinus Tachycardia with AV Block During VVS. Introduction: Neurocardiogenic (vasovagal) syncope is characterized by hypotension and bradycardia. The presence of sinus tachycardia along with AV block during syncope in patients with neurocardiogenic syncope has not been described previously. Methods and Results: Two female patients (18 and 16 years old) with recurrent syncope and documented sinus tachycardia at the time of syncope are described. Patient 1 had recurrent episodes of syncope. During one of these episodes, which occurred while she was being monitored, sinus tachycardia along with high-grade AV block was seen at the time of syncope and hypotension. Patient 2 had a history of recurrent syncope and seizure. During one of these episodes, she was documented to have ventricular asystole lasting for about 39 seconds. The sinus rate was 480 msec at the beginning, before slowing down to 960 msec prior to restoration of sinus rhythm with 1:1 AV conduction. The same scenario was repeated during head-up tilt testing. Both patients were treated successfully with oral disopyramide and, during a follow-up of 28 months and 9 months, have remained symptom-free. Conclusion: Sinus acceleration along with high-grade AV block during syncope and hypotension can occur in some patients with neurocardiogenic syncope. The exact mechanism of this phenomenon is unclear.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8167.1998.tb00901.x
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  • 8
    Electronic Resource
    Electronic Resource
    Posteroseptal Accessory Pathways: An Overview of Anatomical Characteristics, Electrocardiographic Patterns, Electrophysiological Features, and Ablative Therapy (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of interventional cardiology 8 (1995), S. 0 
    Details
    ISSN: 1540-8183
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8183.1995.tb00519.x
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  • 9
    Electronic Resource
    Electronic Resource
    Electroanatomic Mapping for Radiofrequency Ablation of Cardiac Arrhythmias (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cardiovascular electrophysiology 10 (1999), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Nonfluoroscopic Mapping for Cardiac Arrhythmias. Radiofrequency catheter ablation is the current treatment of choice for several cardiac arrhythmias. The conventional approach utilizing intracardiac electrograms during sinus rhythm and during tachycardia has inherent limitations including limited two-dimensional fluoroscopic imaging and the ability to evaluate several potential sites for ablation and to go precisely to the most suitable site. Recently, a nonfluoroscopic three-dimensional electroanatomic system has been developed for mapping arrhythmias. We describe in this report the advantage of utilizing the system in facilitating a successful outcome in three patients with different arrhythmias.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8167.1999.tb00710.x
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  • 10
    Electronic Resource
    Electronic Resource
    Low-threshold GaAs/AlGaAs graded-index separate confinement heterostructure lasers grown by molecular beam epitaxy on oxide-masked Si substrates (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 2499-2501 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Low-threshold GaAs/AlGaAs lasers have, for the first time, been grown selectively on 10 μm stripe openings patterned in oxide on Si substrates. Lateral current confinement provided by side facets reduces edge leakage, and results in threshold currents as low as 75 mA for a 10 μm by 210 μm device, a nearly two-fold improvement over comparable etched ridge waveguide lasers. Spectrum measurements show single longitudinal mode emission near 850 nm. This adaptation of selective heteroepitaxial growth for lateral current confinement of AlGaAs/GaAs lasers on Si substrates, adopted from similar work on GaAs substrates, offers potential for significant threshold current reductions of lasers integrable with Si.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102870
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