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Defibrillation Electrode (defibrillation + electrode)

Distribution by Scientific Domains
Medical Sciences100%

Selected Abstracts

Initial Experience with an Active-Fixation Defibrillation Electrode and the Presence of Nonphysiological Sensing

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 12 2001
RAHUL N. DOSHI
DOSHI, R.N., et al.: Initial Experience with an Active-Fixation Defibrillation Electrode and the Presence of Nonphysiological Sensing. Nonphysiological sensing by a pacing and defibrillation electrode may result in inappropriate defibrillator discharges and/or inhibition of pacing. Active-fixation electrodes may be more likely to sense diaphragmatic myopotentials because of the protrusion of the screw for fixation. In addition, the movement of the fixation screw in an integrated bipolar lead system could also result in inappropriate sensing. This may be increasingly important in patients who are pacemaker dependent because the dynamic range of the autogain feature of these devices is much more narrow. Five of 15 consecutive patients who received a CPI model 0154 or 0155 active-fixation defibrillation electrode with an ICD system (CPI Ventak AV3DR model 1831 or CPI Ventak VR model 1774 defibrillator) are described. In 2 of the 15 patients, nonphysiological sensing appearing to be diaphragmatic myopotentials resulted in inappropriate defibrillator discharges. Both patients were pacemaker dependent. Changes in the sensitivity from nominal to less sensitive prevented inappropriate discharges. In one patient, discreet nonphysiological sensed events with the electrogram suggestive of ventricular activation was noted at the time of implantation. This was completely eliminated by redeployment of the active-fixation lead in the interventricular septum. In two other patients, discreet nonphysiological sensed events resulted in intermittent inhibition of ventricular pacing after implantation. These were still seen in the least sensitive autogain mode for ventricular amplitude. These were not seen on subsequent interrogation 1 month after implantation. Increased awareness of nonphysiological sensing is recommended. The CPI 0154 and 0155 leads seem to be particularly prone to this abnormality. Particular attention should be made when deploying an active-fixation screw for an integrated bipolar lead. This increased awareness is more important when a given individual is pacemaker dependent, which may warrant DFT testing in a least or less sensitive mode in these patients. [source]

A Pilot Study of a Low-Tilt Biphasic Waveform for Transvenous Cardioversion of Atrial Fibrillation: Improved Efficacy Compared with Conventional Capacitor-Based Waveforms in Patients

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 8 2008
BENEDICT M. GLOVER M.D.
Background:The optimal waveform tilt for defibrillation is not known. Most modern defibrillators used for the cardioversion of atrial fibrillation (AF) employ high-tilt, capacitor-based biphasic waveforms. Methods:We have developed a low-tilt biphasic waveform for defibrillation. This low-tilt waveform was compared with a conventional waveform of equivalent duration and voltage in patients with AF. Patients with persistent AF or AF induced during a routine electrophysiology study (EPS) were randomized to receive either the low-tilt waveform or a conventional waveform. Defibrillation electrodes were positioned in the right atrial appendage and distal coronary sinus. Phase 1 peak voltage was increased in a stepwise progression from 50 V to 300V. Shock success was defined as return of sinus rhythm for ,30 seconds. Results:The low-tilt waveform produced successful termination of persistent AF at a mean voltage of 223 V (8.2 J) versus 270 V (6.7 J) with the conventional waveform (P = 0.002 for voltage, P = ns for energy). In patients with induced AF the mean voltage for the low-tilt waveform was 91V (1.6 J) and for the conventional waveform was 158 V (2.0 J) (P = 0.005 for voltage, P = ns for energy). The waveform was much more successful at very low voltages (less than or equal to 100 V) compared with the conventional waveform (Novel: 82% vs Conventional 22%, P = 0.008). Conclusion:The low-tilt biphasic waveform was more successful for the internal cardioversion of both persistent and induced AF in patients (in terms of leading edge voltage). [source]

Initial Experience with an Active-Fixation Defibrillation Electrode and the Presence of Nonphysiological Sensing

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 12 2001
RAHUL N. DOSHI
DOSHI, R.N., et al.: Initial Experience with an Active-Fixation Defibrillation Electrode and the Presence of Nonphysiological Sensing. Nonphysiological sensing by a pacing and defibrillation electrode may result in inappropriate defibrillator discharges and/or inhibition of pacing. Active-fixation electrodes may be more likely to sense diaphragmatic myopotentials because of the protrusion of the screw for fixation. In addition, the movement of the fixation screw in an integrated bipolar lead system could also result in inappropriate sensing. This may be increasingly important in patients who are pacemaker dependent because the dynamic range of the autogain feature of these devices is much more narrow. Five of 15 consecutive patients who received a CPI model 0154 or 0155 active-fixation defibrillation electrode with an ICD system (CPI Ventak AV3DR model 1831 or CPI Ventak VR model 1774 defibrillator) are described. In 2 of the 15 patients, nonphysiological sensing appearing to be diaphragmatic myopotentials resulted in inappropriate defibrillator discharges. Both patients were pacemaker dependent. Changes in the sensitivity from nominal to less sensitive prevented inappropriate discharges. In one patient, discreet nonphysiological sensed events with the electrogram suggestive of ventricular activation was noted at the time of implantation. This was completely eliminated by redeployment of the active-fixation lead in the interventricular septum. In two other patients, discreet nonphysiological sensed events resulted in intermittent inhibition of ventricular pacing after implantation. These were still seen in the least sensitive autogain mode for ventricular amplitude. These were not seen on subsequent interrogation 1 month after implantation. Increased awareness of nonphysiological sensing is recommended. The CPI 0154 and 0155 leads seem to be particularly prone to this abnormality. Particular attention should be made when deploying an active-fixation screw for an integrated bipolar lead. This increased awareness is more important when a given individual is pacemaker dependent, which may warrant DFT testing in a least or less sensitive mode in these patients. [source]

Reduction in Atrial Defibrillation Threshold by a Single Linear Ablation Lesion

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 4 2001
JAMES B. WHITE Ph.D.
Single Lesion Lowers ADFT.Introduction: This study investigated a hybrid approach to reduce the atrial defibrillation threshold (ADFT) by determining the effect of a single linear radiofrequency ablation (RFA) lesion on both the ADFT and activation patterns during atrial fibrillation (AF). Methods and Results: In 18 open chest sheep (45 to 57 kg), coil defibrillation electrodes were placed in a superior vena cava/right ventricular configuration. AF was induced by burst pacing and maintained with acetyl ,-methylcholine (2 to 42 ,L/min). ADFTs were obtained before and after a linear RFA lesion was created in the left atrium (LAL; n = 6), right atrium (RAL; n = 6), or neither atrium as a control (n = 6). In animals receiving an LAL, a 504-unipolar-electrode plaque was sutured to the LA. For animals receiving an RAL, two 504-electrode plaques were placed, one each on the LA and RA. From each plaque, activations were recorded before and after ADFT shocks, and organizational characteristics of activations were analyzed using algorithms that track individual wavefronts. In sham-treated controls, the ADFT did not change. In contrast, LAL reduced ADFT energy 29%, from 4.5 ± 2.3 J to 3.2 ± 2.0 J (P < 0.05). RAL reduced ADFT energy 25%, from 2.0 ± 0.9 J to 1.5 ± 0.7 J (P < 0.05). AF activation was substantially more organized after RFA than before RFA for both the RAL- and LAL-treated animals. Conclusion: A single RFA lesion in either the RA or LA reduces the ADFT in this sheep model. This decrease is associated with an increase in fibrillatory organization. [source]