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  • 1
    Electronic Resource
    Electronic Resource
    Automatic Adjustment of Pacemaker Stimulation Output Correlated with Continuously Monitored Capture Thresholds: A Multicenter Study (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Pacing and clinical electrophysiology 21 (1998), S. 0 
    Details
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Pacing threshold is affected by many factors. A pacing system able to confirm capture at each beat and automatically adjust its output close to the actual pacing threshold is highly desirable. This study evaluates the safety and efficacy of the Autocapture function of the Pacesetter Microny SR+. One hundred thirteen patients were recruited from 16 centers in 7 European countries and followed up for 1 year. All pacemakers were implanted with Pacesetter's low polarization, bipolar leads. The key feature of Autocapture is the immediate delivery of a 4.5 V safety backup pulse 62.5 ms after any ineffective ongoing low output pulse. Holter recordings confirmed total reliability of this feature without any exit block. The measured evoked response (ER) signal was stable over time. Acute and chronic pacing thresholds measured by VARIO and Autocapture tests correlated (r 〉 0.79) over the period of the study. The incidence of backup pulses was 1.1% during pacing. With Autocapture programmed ON, the overall total current consumption was 4.1 μA for VVI and 5.0 μA for VVIR pacing. Tbis study proved that the Autocapture safely and reliably regulates the pacemaker's output according to the prevailing threshold thus providing maximum patient safety and prolonging service life.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8159.1998.tb00244.x
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  • 2
    Electronic Resource
    Electronic Resource
    Clinical Performance of a Ventricular Automatic Capture Verification Algorithm (2005)
    350 Main Street , Malden , MA 02148-5018 , USA and 9600 Garsington Road , Oxford OX4 2DQ , UK . : Blackwell Science Inc
    Pacing and clinical electrophysiology 28 (2005), S. 0 
    Details
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background: This study was conducted to evaluate the clinical performance of the ventricular automatic capture feature as implemented in the Insignia I Ultra pacemaker system (Guidant) utilizing a variety of ventricular leads Currently, the optimal programming of the pacemaker output considers both pacemaker efficiency (prolonging battery longevity) and patient safety (adequate safety margin). The ability of a pacemaker to automatically adjust the ventricular output above the pacing threshold while maintaining the appropriate safety margin has been explored since the early 1970s and is only available today in conjunction with a specific low polarization lead system. Methods: One hundred and five patients were enrolled from 17 European centers utilizing 31 different types of ventricular leads were followed through their 3-month follow-up visit. There were no restrictions on the type of ventricular leads used. Results: The average mean difference between the commanded autothreshold test (0.652 + 0.335 V) and the manual threshold test (0.651 + 0.335 V) was 0.001 + 0.49 (P 〈 0.0001). The average mean difference between the ambulatory autothreshold test (0.696 + 0.322 V) and the commanded autothreshold test (0.682 + 0.315 V) was 0.002 + 0.74 (P 〈 0.0001). Holter recordings confirmed that there were no loss of capture incidences without a backup pulse being delivered. In addition, the mean number of backup pulses delivered in a 24-hour period was less than 0.1% of the total number of paced beats. Conclusions: This study provided that the automatic capture feature while using a variety of leads accurately determines the ventricular stimulation threshold and safely delivers a backup pulse when required.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8159.2005.00196.x
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  • 3
    Electronic Resource
    Electronic Resource
    Clinical Experience with an Automatic Threshold Tracking Algorithm Study (2003)
    350 Main Street , Malden , MA 02148-5018 , U.S.A . : Blackwell Publishing
    Pacing and clinical electrophysiology 26 (2003), S. 0 
    Details
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The automatic threshold tracking pacing system algorithm developed by St. Jude Medical, verifies ventricular capture beat by beat by recognizing the evoked response (ER) following each pacemaker stimulus. The present automatic threshold tracking function requires a bipolar ventricular lead with low polarization. The aim of this study was to evaluate a new algorithm developed to use with unipolar leads with different levels of polarization. An external pacemaker with the ability to sense intrinsic R waves and measure ER signals, as well as deliver stimulus, was used. An algorithm for detecting the true ER in a unipolar sensing configuration (tip-case) was developed. Based on the assumption that the true evoked R wave amplitude is independent of the stimulation amplitude, the algorithm calculates and subtracts the polarization present at any pacing stimulus from the measured ER. The resulting signal is analyzed to verify capture. This study comprises 35 patients of which 26 were new implants and 9 had chronic leads. The automatic threshold-tracking algorithm was calibrated for each patient and pacing was performed at different pulse amplitudes and pulse duration. Capture was verified for each paced beat. The recordings were stored for later comparison with the tape-recorded intracardiac heart signals. The new algorithm correctly verified capture or loss of capture for every single analyzed beat at the different pacing outputs in every individual patient. The results from this initial study suggests that the new ER detection principle will allow automatic threshold tracking to be used not only with low polarization bipolar leads but with most leads. (PACE 2003; 26:2219–2224)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8159.2003.00350.x
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  • 4
    Electronic Resource
    Electronic Resource
    Bidirectional Defibrillation Using Implantable Defibrillators: A Prospective Randomized Comparison Between Pectoral and Abdominal Active Generators (2001)
    Oxford, UK : Blackwell Futura Publishing, Inc.
    Pacing and clinical electrophysiology 24 (2001), S. 0 
    Details
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: SANDSTEDT, B., et al.: Bidirectional Defibrillation Using Implantable Defibrillators: A Prospective Randomized Comparison Between Pectoral and Abdominal Active Generators. The objective of this study was to compare the effects of active abdominal and pectoral generator positions on DFTs in a bidirectional tripolar ICD system. Twenty-five consecutive patients had ICD systems implanted under general anesthesia. A transvenous single lead bipolar defibrillation system and an active 57-cc test emulator in the abdominal and pectoral positions were used in the same patient. A randomized, alternating stepdown protocol was used starting at 15 J with 3-J decrements until failure. The mean implantation time was 114 ± 23 minutes, the mean arrhythmia duration was 14.5 ± 1.5 seconds, and the mean recovery time was 5.4 ± 1.1 minutes. The mean DFTs in the abdominal and pectoral positions were 10.9 ± 5.1 and 9.7 ± 5.2 J, respectively (NS), the mean intraindividual DFT difference (abdominal minus pectoral) was −0.89 ± 4.15 J (range −9.5 to + 5.8 J). The 95% confidence interval showed a −2.60 to + 0.82 J mean difference (NS). The DFT was 〈 15 J in 72% and 88% of the patients and the defibrillation impedance was 41 ± 3 and 44 ± 3 Ω, abdominal versus pectoral positions. There was no difference in DFT between active abdominal and pectoral generator bidirectional tripolar defibrillation. The pectoral position may be considered the primary option, but in cases of high DFTs the abdominal site should be considered an alternative to adding a subcutaneous patch. In some patients, the anatomy may favor an abdominal position. Possible differences in the long-term functionality on the leads are not yet well known and need to be further evaluated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9592.2001.01343.x
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  • 5
    Electronic Resource
    Electronic Resource
    Short-and Long-Term Performance of a Tripolar Down-Sized Single Lead for Implantable Cardioverter Defibrillator Treatment: A Randomized Prospective European Multicenter Study (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Pacing and clinical electrophysiology 21 (1998), S. 0 
    Details
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A new, thinner (10 Fr) and more flexible, single-pass transvenous endocardial ICD lead, Endotak DSP, was compared with a conventional lead, Endotak C, as a control in a prospective randomized multicenter study in combination with a nonactive can ICD. A total of 123 patients were enrolled, 55 of whom received a down-sized DSP lead. Lead-alone configuration was successfully implanted in 95% of the DSP patients vs 88% in the control group. The mean defibrillation threshold (DFT) was determined by means of a step-down protocol, and was identical in the two groups, 10.5 ± 4.8 J in the DSP group versus 10.5 ± 4.8 J in the control group. At implantation, the DSP mean pacing threshold was lower, 0.51 ± 0.18 V versus 0.62 ± 0.35 V (p 〈 0.05) in the control group, and the mean pacing impedance higher, 594 ± 110 Ω vs 523 ± 135 Ω (p 〈 0.05). During the follow-up period, the statistically significant difference in thresholds disappeared, while the difference in impedance remained. Tachyarrhythmia treatment by shock or antitachycardia pacing (ATP) was delivered in 53% and 41%, respectively, of the patients with a 100% success rate. In the DSP group, all 28 episodes of polymorphic ventricular tachycardia or ventricular fibrillation were converted by the first shock as compared to 57 of 69 episodes (83%) in the control group (p 〈 0.05). Monomorphic ventricular tachycardias were terminated by ATP alone in 96% versus 94%. Lead related problems were minor and observed in 5% and 7%, respectively. In summary, both leads were safe and efficacious in the detection and treatment of ventricular tachyarrhythmias. There were no differences between the DSP and control groups regarding short- or long-term lead related complications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8159.1998.tb01128.x
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  • 6
    Electronic Resource
    Electronic Resource
    First European Experience Using Excimer Laser for the Extraction of Permanent Pacemaker Leads (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Pacing and clinical electrophysiology 21 (1998), S. 0 
    Details
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: An Excimer Laser system for the extraction of permanent pacemaker leads has been developed by Spectranetics Inc. and Dr. Charles L. Byrd. The laser energy is emitted at the tip of a flexible, fiberoptic 12F sheath that permits the removal of leads with a max outer diameter of 7.1F. The CVX-300 Excimer Laser source is a xenon chloride laser with an output of 308 nm not visible to the human eye. This cool cutting laser has an absorption depth of 0.06 mm, the energy being absorbed by proteins and lipids. In clinical practice this means that the fibrotic sheaths usually surrotinding the leads can be cut without damaging the endothelial wall or the insulation of leads, due to these characteristics the sheath can, however, not pass over tines. For the freeing of lead tips, locking stylets and outer sheaths are combined to perform counter traction. Results: From 8/96 to 5/97 50 leads (38 atrial, 12 ventricular) from 45 patients (22 females, 23 males, mean age 65.1 years, range 32–94) were extracted using the Excimer Laser at our institution. Mean lead implantation time was 47.7 months (range 10.5–351.7). Indication for extraction was suspected J-wire fracture in 16 leads, prophylactic in 8 leads, infection in 12 leads, exit block in 4 leads and other reasons in 10 leads. Mean extraction time, excluding reimplantation, was 10 minutes (range 1–50). The objective of the procedure (normally complete lead removal) was accomplished in all cases but three. All intended lead replacements were successful. No complications occurred. All patients left the hospital in good condition, one patient died, within 30 days due to progressive heart failure. Conclusions: Lead extraction with Excimer Laser seems to be a safe and efficacious procedure. However, due to the inherent risks appropriate training and experience are essential. If the initial promising results can be maintained, indications for the removal of permanent pacing leads may widen considerably.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8159.1998.tb01102.x
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  • 7
    Electronic Resource
    Electronic Resource
    Cardiac Lead Extraction with a Novel Locking Stylet (2000)
    Springer
    Journal of interventional cardiac electrophysiology 4 (2000), S. 591-593 
    Details
    ISSN: 1572-8595
    Keywords: defibrillator lead ; pacing lead ; lead removal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Extraction of chronically implanted pacing and defibrillator leads is facilitated by using specialized locking stylets placed in the lead to allow application of traction and to stabilize the lead during sheath dissection of fibrotic tissue. We report the initial multicenter series of cases using a novel lead locking device (LLD). In 57 consecutive patients presenting at 6 institutions for lead extraction, 99 leads were treated using the LLD. After removing the pulse generator, leads were severed, the inner coil dilated and an LLD was successfully inserted and locked in the inner lumen of 95/99 (96±%) leads. With traction applied to the LLD, a variety of sheaths were advanced over the lead body to separate it from adhesions. In 97/99 (98±%) leads, all or most of the lead was removed via the implant vein; 2 leads were removed via the femoral vein. No major complications were observed. The LLD deploys safely and reliably, and provides stable support for advancement of dissecting sheaths.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026561414148
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