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  • 1
    ISSN: 1542-474X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The planned MADIT-CRT trial is designed to determine if CRT-D will reduce the risk of mortality and HF events by approximately 25% in subjects with ischemic (NYHA class I-II) and non-ischemic (NYHA class II) cardiomyopathy, left ventricular dysfunction (EF ≤ 0.30), and prolonged intraventricular conduction (QRS duration ≥ 130 ms).
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Heart Block in a Mouse Model of Myotonic Dystrophy. Introduction: A mouse strain lacking functional myotonic dystrophy protein kinase (DMPK) has recently been developed. DMPK-/- mice exhibit muscular and conduction abnormalities consistent with the disease; however, the site of abnormal cardiac conduction is unknown. Methods and Results: Nine homozygous DMPK-/- mice and seven age matched wild-type (WT) controls underwent in vivo electrophysiologic studies using an endocardial 2-French catheter. Baseline intervals as well as Wenckebach and 2:1 cycle lengths were measured to assess AV and ventriculoatrial (VA) conduction. Effective refractory periods (ERP) and functional refractory periods were determined during atrial and ventricular premature stimulation. His-bundle recordings were obtained on all the studied animals (16/16). DMPK-/- mice bad significantly prolonged PR (48.1 ± 5.5 vs 40.9 ± 3.9 msec, P = 0.010) and AH (36.7 ± 4.0 vs 31.6 ± 4.8 msec, P = 0.037) intervals compared to WT controls. HV intervals were very significantly prolonged as well (14.7 ± 2.0 vs 10.3 ± 0.8 msec; P 〈 0.0001). Three of 9 DMPK-/- and I of 7 WT mice exhibited VA block. Atrial ERP was reached before AV node ERP in 2 (22%) of 9 of the knockout mice and 5 (71%) of 7 of the controls (P = 0.06). Only one mouse (DMPK-/-) exhibited infra-Hisian block on premature atrial stimulation. Conclusion: In this mouse model of myotonic dystrophy, AV conduction abnormalities were localized to the supra-Hisian and infra-Hisian conduction tissues, with a higher predilection to the latter, a finding similar to the human form of the disease.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of noninvasive electrocardiology 4 (1999), S. 0 
    ISSN: 1542-474X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background:The purpose of this study was to compare the utility of T-wave alternans and dispersion markers for predicting vulnerability to ventricular arrhythmias. Microvolt level T-wave alternans, QT dispersion (QTd), JT dispersion, and other dispersion indices have been postulated as noninvasive markers of vulnerability to ventricular arrhythmias. However, T-wave alternans has not been directly compared to dispersion markers in the same patient population. Methods:Twenty-four patients underwent electrophysiological study to investigate recent syncope, ventricular tachycardia, or ventricular fibrillation. Digitized orthogonal ECGs were obtained to investigate the presence of T-wave alternans using spectral analysis, and standard 12-lead ECGs were obtained for QT and JT dispersion analysis. Results:T-wave alternans measurements showed greater sensitivity than QT or JT dispersion, but similar results as the variation coefficient of the JT interval. There was no statistically significant difference in specificity, predictive values, or clinical accuracy between T-wave alternans and any of the dispersion markers (P = N.S.). The combination of increased QT or JT dispersion and T-wave alternans was the most specific predictor. Conclusions:Heterogeneity of repolarization amplitude and duration may both be important noninvasive ECG markers of ventricular vulnerability. In this small group of high-risk patients, T-wave alternans has similar clinical accuracy as the ECG interlead repolarization dispersion markers. The predictive ability of these markers may improve with standardization of methodology or a combination of these approaches. A.N.E. 1999;4(3):274–280
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Pacing and clinical electrophysiology 23 (2000), S. 0 
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The Defibrillators in Nonischemic Cardiomyopathy Treatment Evaluation (DEFINITE) is a multicenter randomized trial. Patients will have nonischemic Cardiomyopathy (LVEF ± 35%), a history of symptomatic heart fail-ure and spontaneous arrhythmia (〉 10 PVCs/hour or nonsustained ventricular tachycardia defined as 3-15 beats at a rate of 〉 120 beats/min) on Holter monitor or telemetry within the past 6 months. Patients will be randomized to an implantable cardioverter defibrillator (ICD) versus no ICD. All patients will re-ceive standard oral medical therapy for heart failure including angiotensin converting enzyme inhibitors and β-blockers (if tolerated). Patients will be followed for 2-3 years. The primary endpoint will be total mortality. Quality-of-life and pharmacoeconomics analyses will also be performed. A registry will track patients who meet basic inclusion criteria but are not randomized. We estimate an annual total mortality of 15% at 2 years in the treatment arm that does not receive an ICD. The ICD is expected to reduce mor-tality by 50%. Approximately 204 patients will be required in each treatment group. Twenty-five centers will be included in a trial designed to last an estimated 4 years.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    350 Main Street , Malden , MA 02148-5018 , USA . : Blackwell Futura Publishing, Inc.
    Pacing and clinical electrophysiology 26 (2003), S. 0 
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: MARENCO, J.P., et al.: Use of the AutoCapture Pacing System with Implantable Defibrillator Leads. Introduction: Previous studies using various bipolar pacemaker leads have shown that the AutoCapture (AC) Pacing System is able to verify ventricular capture and regulate pacing output, increasing patient safety with respect to unexpected threshold changes and potentially prolonging device longevity. An increasing number of patients with implantable cardioverter defibrillators (ICDs) require ventricular pacing that contributes to a shortening of longevity of these systems. This prospective study tested the compatibility of the AC system with bipolar ICD leads. Methods: The AC algorithm was evaluated prior to ICD testing in 30 ICD recipients. A single coil, active fixation, true bipolar ventricular lead was implanted in 21 patients, and a dual coil, passive fixation, integrated bipolar ventricular lead was implanted in 9 patients. A ventricular evoked response sensitivity test and an AC threshold test were performed using a pacemaker with the ventricular AC algorithm. Results: AC was recommended in 22/30 (73.3%) of implants, including 20/21 (95.2%) with the single coil and 2/9 (22.2%) with the dual coil lead. Mean polarization was lower ( 1.23 ± 0.95 mV vs 3.70 ± 2.33 mV, P = 0.013 ) while the mean evoked response was higher ( 18.04 ± 8.29 mV vs 10.13 ± 4.22 mV, P = 0.002 ) with the single coil leads. Conclusion: Automatic threshold tracking using the AC is compatible with ICD leads. Leads with lower polarization and greater evoked response are more likely to result in recommendation of AC use. Use of this system offers the potential for increasing ICD generator longevity and improving patient safety in response to late unexpected threshold increases. (PACE 2003; 26[Pt. II]:471–473)
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thrombosis and thrombolysis 7 (1999), S. 123-129 
    ISSN: 1573-742X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-904X
    Keywords: ischemia-reperfusion injury ; hepatic clearance ; anti-pyrine ; cytokines ; interleukin-6 ; tumor necrosis factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. All transplanted solid organs experience some degree of ischemia-reperfusion (I-R) injury. This I-R injury can contribute to graft dysfunction which stems in part from the acute phase response and a resultant host of cytokines. Recent evidence suggests that organs remote to the site of I-R injury can be affected by circulating cytokines originating from these I-R injuries. Since many of these acute phase cytokines inhibit hepatic cytochrome P-450 (CYP) enzymes, we chose to investigate whether extrahepatic I-R injuries could influence hepatic oxidative drug metabolism. Methods. Fifteen dogs were divided into three surgical groups: (I) sham I-R; (II) bilateral normothermic renal I-R; and (III) normothermic intestinal I-R. Antipyrine (AP) was selected as a model substrate and administered intravenously at a dose of 10 mg/kg. AP serum concentrations were determined by HPLC and cytokine activity (IL-1, IL-6, and TNFα) was measured via bioassay. Serial AP clearance and serum cytokine concentrations were determined 3 days prior to and at 4 hr, 24 hr, 3 days and 7 days after surgery. Hematology and blood chemistries were monitored throughout the study period. Results. AP clearance was significantly reduced in groups II and III at 4 and 24 hrs post-I-R injury, while AP binding and apparent volume of distribution were unaffected. Peak levels of TNF and IL-6 activity occurred at 1 and 4 hours, respectively. IL-1 activity was not detected in any group. AP clearance correlated strongly to circulating levels of IL-6 (r = −0.789, p = 0.0002). Conclusions. Our findings indicate that extrahepatic I-R injury can affect hepatic oxidative drug metabolism and this effect is mediated in part by circulating cytokines.
    Type of Medium: Electronic Resource
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