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JOHN P. BOURKE LYNNE HOWELL ALAN MURRAY WILLIAM E. HILL J. CAMPBELL COWAN KEVIN BEATT JOAN ERRINCTON STUART JAMESON RONALD G. GOLD 《Pacing and clinical electrophysiology : PACE》1989,12(8):1419-1425
A randomized prospective study was undertaken to compare the electrical performances of three permanent, endocardial, tined pacing leads with different electrode designs--sintered platinum, vitreous carbon, and porous carbon. Ninety-nine patients received one of the leads (S80 31; 423S 32; S100 36). Acute R wave amplitude and ST elevation of the native endocardial electrogram, voltage threshold, impedance, and current flow at four pulse durations (0.25-1.0 msec) were measured. Voltage thresholds were measured noninvasively at each of four pulse durations at 2 days and 1, 3, and 6 months after implantation. No significant differences were found in sensing properties, or current flow at threshold at 0.5 msec pulse duration. The 423S lead had a significantly higher impedance at threshold and both a higher impedance and lower current flow at 5 V. No significant differences in threshold voltages were found between the three leads at any pulse duration, at any of the assessed times after implantation. Six-month thresholds for the S80, 423S, and S100 leads were 1.18 +/- 0.35, 1.17 +/- 0.29, and 1.06 +/- 0.38 V respectively at 0.5 msec pulse duration. Differences between 'high performance' pacing leads need to be of a greater order of magnitude before they can be exploited to give any real clinical advantage to patients. 相似文献
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A Pilot Study: Defibrillation Thresholds in Dogs are Similar with Isoflurane, Halothane, and Pentobarbital 总被引:1,自引:0,他引:1
ALISON S. JARVIS STUART P. LAHTINEN 《Pacing and clinical electrophysiology : PACE》1994,17(3):280-285
The objective of this pilot study was to determine if three common anesthetic drugs have differing effects on the measurement of defibrillation thresholds (DFT) in dogs. The drugs compared were pentobarbital, isoflurane, and halothane. We used six dogs, which were surgically instrumented, in a chronic study design. Each dog had two internal defibrillation patches placed on its heart, which were used to deliver the defibrillation energy. DFT was determined while each dog was anesthetized under each of the listed drugs in a crossover design. This pilot study suggests that differences in DFT due to the anesthetic drugs is not significant in studies with low numbers of animals (halothane 14.5 ± 1.0, isoflurane 14.2 ± 1.0, pentobarbital 12.8 ± 1.0;P = NS; mean ± SE). Tbe variation in DFT between individual animals is much larger than the difference in DFT due to the drugs. 相似文献
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The Effect of 50 Hz External Electrical Interference on Implanted Cardiac Pacemakers 总被引:2,自引:0,他引:2
GERALD C. KAYE GHAZWAN S. BUTROUS ALI ALLEN STUART J. MELDRUM JOHN G. MALE † A. JOHN CAMM 《Pacing and clinical electrophysiology : PACE》1988,11(7):999-1008
The effects of injected 50 Hz alternating current on the function of cardiac pacemakers has been observed in 18 patients with implanted unipolar VVI units. Current, in the range 0-600 microA was applied via electrodes attached to the patients' upper body and feet and fed from a specially designed current injection unit at the bedside. Most implanted pacemakers reverted to interference mode in the current range 29-250 microA. At current levels just below the reversion current all units developed irregular and inappropriate pacing. This current level was pacemaker dependent and varied in the range 27-246 microA. The total reversion current depended on the location of the injecting electrodes and on the patients' posture. The sensitivity of the units to injected interference was increased by deep inspiration. Temporary pacing catheters fitted to an additional ten patients were used to monitor the interference voltage which would be sensed by an implanted unit. This voltage was similarly dependent on patient posture and on deep respiration. Current injection has proved to be a safe, controllable and reproducible method of testing the sensitivity of implanted pacemakers to 50 Hz external interference. 相似文献
6.
Forty-three patients were prospectively studied following tracheo-oesophageal puncture at the time of laryngectomy (primary voice restoration). Blom-Singer voice prostheses were used. The surgery was regarded as successful if a patient continued to use the voice prosthesis as the major means of communication with clear intelligibility 4 months after the operation. Using this criterion, the success in this series was 70%. No attempt was made to assess the quality of speech. Complications and causes of failure are discussed. 相似文献
7.
Present address: Program in Scientific Computing and Computational Mathematics, Division of Applied Mechanics, Durand 252, Stanford University, California 94305, USA. In order to accomplish the transition from avascular to vasculargrowth, solid tumours secrete a diffusible substance known astumour angiogenesis factor (TAF) into the surrounding tissue.Endothelial cells which form the lining of neighbouring bloodvessels respond to this chemotactic stimulus in a well-orderedsequence of events consisting, at minimum, of a degradationof their basement membrane, migration, and proliferation. Amodel mechanism is presented which includes the diffusion ofthe TAF into the surrounding host tissue and the response ofthe endothelial cells to the chemotactic stimulus. The modelaccounts for the main observed events associated with the endothelialcells during the process of angiogenesis (i.e. cell migrationand proliferation); the numerical results compare very wellwith experimental observations. The situation where the tumour(i.e. the source of TAF) is removed and the vessels recede isalso considered. 相似文献
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Ventricular Tachycardia/Ventricular Fibrillation Ablation in the Setting of Ischemic Heart Disease 总被引:1,自引:0,他引:1
FRANCIS MARCHLINSKI M.D. FERMIN GARCIA M.D. AMIR SIADATAN M.D. WILLIAM SAUER M.D. STUART BELDNER M.D. ERICA ZADO P.A.-C. HENRY HSIA M.D. DAVID LIN M.D. JOSHUA COOPER M.D. RALPH VERDINO M.D. EDWARD GERSTENFELD M.D. SANJAY DIXIT M.D. REA RUSSO M.D. DAVID CALLANS M.D. 《Journal of cardiovascular electrophysiology》2005,16(S1):S59-S70
Recurrent ventricular tachycardia (VT) in the setting of coronary artery disease is frequently a life-threatening electrophysiologic emergency. Even in patients with an implantable defibrillator, recurrent VT is frequently accompanied by repeated and disabling shock therapy. Catheter ablative therapy offers the ability to provide immediate control of recurrent VT. Long-term elimination of VT should be anticipated in most patients. This article reviews the strategies, tools, techniques, and expected outcome for catheter ablation of stable and unstable ventricular arrhythmias in the setting ischemic heart disease. 相似文献
10.
Serum interleukin-8 in inflammatory bowel disease 总被引:2,自引:0,他引:2
SUSAN C. JONES STUART W. EVANS ALAN J. LOBO MIROSLAV CESKA ANTHONY T. R. AXON JOHN T. WHICHER 《Journal of gastroenterology and hepatology》1993,8(6):508-512
To investigate the relationship between serum concentrations of interleukin-8 (IL-8) and disease activity in inflammatory bowel disease, serum IL-8 concentrations were measured by enzyme-linked immunosorbent assay (ELISA) in 93 patients. Interleukin-8 levels were compared with plasma interleukin-6 (IL-6) levels in 80 of these patients. Interleukin-8 levels were also measured in ten patients with active Crohn's disease, before and after treatment with a defined formula polymeric diet. Of these patients, 70 out of 93 IL-8 concentrations were below the detection limit of the assay. Levels were higher in patients with active ulcerative colitis (median < 20 pg/mL, 75th centile value = 190) compared with inactive disease (median and 75th centile value < 20; P 0.05). Interleukin-8 concentrations correlated with a combined score for disease severity and extent (P= 0.01). Thirty-eight per cent (8/20) of patients with active Crohn's disease also had high levels of IL-8 but there was no significant difference between active and inactive disease. There was no correlation between serum IL-8 and plasma IL-6; on the contrary, very few patients had raised blood levels of both cytokines. In the diet treated group, serum IL-8 fell significantly after treatment (median = 37 pg/mL, range < 20–4615 before treatment, median < 20, range < 20–104 after treatment; P= 0.03). The results suggest that although IL-8 may be involved in the inflammatory process in inflammatory bowel disease, it is a poor marker of disease activity. 相似文献