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  • 1
    Electronic Resource
    Electronic Resource
    Autocapture Enhancements: Unipolar and Bipolar Lead Compatibility and Bipolar Pacing Capability on Bipolar Leads (2003)
    350 Main Street , Malden , MA 02148-5018 , USA . : Blackwell Futura Publishing, Inc.
    Pacing and clinical electrophysiology 26 (2003), S. 0 
    Details
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: BINNER, L., et al.: Autocapture Enhancements: Unipolar and Bipolar Lead Compatibility and Bipolar Pacing Capability on Bipolar Leads. Beat-by-beat Autocapture maximizes device longevity by minimizing stimulus amplitude while assuring patient safety. Currently, Autocapture permits use of only bipolar leads. The authors have devised a detection method that operates with unipolar and bipolar leads and covers all pacing and sensing combinations (but bipolar pace and sense simultaneously). This new detection method for unipolar sensing uses the integral of the negative portion of the unipolar evoked response as a robust capture detection feature. When using bipolar leads, the method provides the flexibility of bipolar or unipolar pacing. In this study, unipolar ventricular intracardiac electrograms (EGMs) were recorded in 71 patients, 73.7 ± 9.9 years of age; 9 with high polarization, 62 with low polarization. High polarization had polished platinum or activated carbon electrodes. Low polarization had TiN, platinized platinum, or IrOx electrodes. The intracardiac EGMs were recorded 544 ± 796 days after implant. The pacemakers performed an automatic capture threshold test while the intracardiac EGM signals were recorded in a programmer. These digitized signals were saved for off-line analysis. The unipolar evoked response was calculated at up to six (depending on capture threshold) pacing voltages and the polarization integral at 4.5 V and at loss of capture. An automatic calibration algorithm determined if the signal-to-noise ratio was adequate for Autocapture operation. Autocapture was possible with 60 of 62 of the low polarizations, and with 6 of 9 of the high polarizations. The average values from the data collected were: average unipolar evoked response - 4.1 ± 2.1  mV , average peak negative voltage - 10.0 ± 3.7  mV , average polarization 0.3 ± 0.34 mV, and average signal-to-noise ratio (unipolar evoked response/polarization) 38 ± 71. In all cases the algorithm correctly determined the appropriateness of using Autocapture with the electrodes tested and the unipolar evoked response threshold to be used. (PACE 2003; 26[Pt. II]:221–224)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9592.2003.00020.x
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  • 2
    Electronic Resource
    Electronic Resource
    Impact of Fusion Avoidance on Performance of the Automatic Threshold Tracking Feature in Dual Chamber Pacemakers: A Multicenter Prospective Randomized Study (2002)
    Oxford, UK : Blackwell Futura Publishing, Inc.
    Pacing and clinical electrophysiology 25 (2002), S. 0 
    Details
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: CANDINAS, R., et al.: Impact of Fusion Avoidance on Performance of the Automatic Threshold Tracking Feature in Dual Chamber Pacemakers: A Multicenter Prospective Randomized Study. The Autocapture algorithm enables automatic capture verification on a beat-by-beat basis by recognizing the evoked response signal following each pacemaker stimulus. The algorithm intends to increase patient safety while decreasing energy consumption. However, the occurrence of fusion beats, particularly during dual chamber pacing, may limit the energy saving effect of Autocapture. The aim of this multicenter, prospective, randomized study was to evaluate the impact of the Fusion Avoidance (FA) algorithm on the incidence of fusion beats. Thirty-eight patients (mean age 69 ± 13 years) with intrinsic AV conduction who were implanted with an Affinity DR were studied. After programming a PV/AV delay of 120/190 ms, patients were randomized to FA On or Off. Each group was further randomized with respect to activation of the AutoIntrinsic Conduction Search (AICS) algorithm. The total number of beats, ventricular paced beats, fusion beats, backup pulses, and threshold searches were analyzed from 24-hour Holter recordings. The number of total beats was comparable in both FA groups. The number of total ventricular paced beats, fusion beats, backup pulses, and threshold searches were significantly reduced in the FA On group (% reduction: 68% P 〈 0.001, 75% P 〈 0.01, 95% P 〈 0.01, and 94% P 〈 0.05, respectively). The number of ventricular paced beats with full capture was significantly reduced when AICS was activated (P 〈 0.05). In conclusion, the FA algorithm substantially reduces the amount of ventricular paced beats, fusion beats, unnecessary backup pulses and threshold searches, and therefore, provides added benefits in energy saving obtained by Autocapture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9592.2002.01540.x
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  • 3
    Electronic Resource
    Electronic Resource
    Reduction of Pacing Output Coupling Capacitance for Sensing the Evoked Response (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: SPERZEL, J., et al.: Reduction of Pacing Output Coupling Capacitance for Sensing the Evoked Response. Sensing of the intracardiac evoked response (ER) after a pacing stimulus has been used in implantable pacemakers for automatic verification of capture. Reliable detection of ER is hampered by large residual afterpotentials associated with pacing stimuli. This led to the development of various technological solutions, like the use of triphasic pacing pulses and low polarizing electrode systems. This study investigated the effect of reducing the coupling capacitance (CC) in the pacemaker output circuitry on the magnitude of afterpotential, and the ability to automate detection of ventricular evoked response. A CC of 2.2 μF and four different blanking and recharge time settings were clinically tested to evaluate its impact on sensing of the ventricular ER and pacing threshold. Using an automatic step-down threshold algorithm, 54 consecutive patients, aged 70 ± 10 years with acutely (n = 27) or chronically (n = 27) implanted ventricular pacing leads were enrolled for measurement testing. Routine measurements, using a standard pacing system analyzer (PSA), were (mean ± SD) impedance 569 ± 155 Ω, R wave amplitude baseline to peak 9.8 ± 3.7 mV and threshold 0.9 ± 0.7 V at 0.4-ms pulse width. This new capture verification scheme, based on a CC of 2.2 μF and recharge/blanking timing setting of 10/12 ms, was successful in 52 patients which is equivalent to a success rate of 96%. In a subgroup of 26 patients implanted with bipolar ventricular leads (10 chronic, 16 acute), data were collected in unipolar (UP) and bipolar (BP) pace/sense configurations. Also, ER signals were recorded with two different band-pass filters: a wider band (WB) of 6–250 Hz and a conventional narrow band (NB) of 20–100Hz. WB sensing from UP lead configuration yielded statistically significant larger signal to artifact ratios (SAR) than the other settings (P 〈 0.01). A dedicated unipolar ER sensing configuration using a small output capacitor and a wider band-pass filter enables adequate automatic capture verification, without any restrictions on pacing lead models or pacing/sensing configurations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9592.2001.01377.x
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  • 4
    Electronic Resource
    Electronic Resource
    Prospective Randomized Comparison of Two Defibrillation Safety Margins in Unipolar, Active Pectoral Defibrillator Therapy (2003)
    350 Main Street , Malden , MA 02148-5018 , USA . : Blackwell Futura Publishing, Inc.
    Pacing and clinical electrophysiology 26 (2003), S. 0 
    Details
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: CARLSSON, J., et al.: Prospective Randomized Comparison of Two Defibrillation Safety Margins in Unipolar, Active Pectoral Defibrillator Therapy. Various techniques are used to establish defibrillation efficacy and to evaluate defibrillation safety margins in patients with an ICD. In daily practice a safety margin of 10 J is generally accepted. However, this is based on old clinical data and there are no data on safety margins using current ICD technology with unipolar, active pectoral defibrillators. Therefore, a randomized study was performed to test if the likelihood of successful defibrillation at defibrillation energy requirement (DER) +5 J and +10 J is equivalent. Ninety-six patients (86 men; age 61.0 ± 10.3 years; ejection fraction 0.341 ± 0.132 ; coronary artery disease [n = 65],dilated cardiomyopathy [n = 18], other [n = 13]) underwent implantation of an active pectoral ICD system with unidirectional current pathway and a truncated, fixed tilt biphasic shock waveform. The defibrillation energy requirement (DER) was determined with the use of a step-down protocol (delivered energy 15, 10, 8, 6, 4, 3, 2 J). The patients were then randomized to three inductions of ventricular fibrillation at implantation and three at predischarge testing with shock strengths programmed to DER + 5 J at implantation and + 10 J at predischarge testing or vice versa. The mean DER in the total study population was7.88 ± 2.96 J. The number of defibrillation attempts was 288 for +5 J and 288 for +10 J. The rate of successful defibrillation was 94.1% (DER + 5 J) and 98.9% (DER + 10 J;P 〈 0.01for equivalence). Charge times for DER + 5 J were significantly shorter than for DER + 10 J (3.65 ± 1.14vs5.45 ± 1.47 s; P 〈 0.001). A defibrillation safety margin of DER + 5 J is associated with a defibrillation probability equal to the standard DER + 10 J. In patients in whom short charge times are critical for avoidance of syncope, a safety margin of DER + 5 J seems clinically safe for programming of the first shock energy. (PACE 2003; 26[Pt. I]:613–618)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9592.2003.00102.x
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  • 5
    Electronic Resource
    Electronic Resource
    Evaluation of a Dual Chamber Implantable Cardioverter Defibrillator for the Treatment of Atrial and Ventricular Arrhythmias (2003)
    350 Main Street , Malden , MA 02148-5018 , USA . : Blackwell Futura Publishing, Inc.
    Pacing and clinical electrophysiology 26 (2003), S. 0 
    Details
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: BORIANI, G., et al.: Evaluation of a Dual Chamber Implantable Cardioverter Defibrillator for the Treatment of Atrial and Ventricular Arrhythmias. Eighty-nine patients with a documented history of atrial tachyarrhythmias or fibrillation (AF) received a cardioverter defibrillator designed to selectively differentiate and treat atrial and ventricular arrhythmias. Twenty-two patients received a coronary sinus lead and, therefore, could use a separate shock vector for selective treatment of atrial tachyarrhythmias/AF. The device is designed to treat tachyarrhythmias with antitachycardia pacing (ATP) and/or shock therapy using an atrial and/or a ventricular shock vector. Patients underwent induction and shock termination of atrial or dual tachyarrhythmias (AF/VF) to verify proper device function and to measure the arrhythmia detection time with enhancements and preventive algorithms programmed On and Off, respectively. Detection time for 329 VF inductions was 2.41 ± 0.64  seconds with enhancements On and 2.29 ± 0.47 with enhancements Off (NS). At implant or predischarge, 283 AF and/or AF/VF (121 atrial and 162 atrial/ventricular fibrillation) were induced. Shock conversion efficacy was 89.8% with AF conversion energies ranging from 0.9 to 27 J. Thirteen of the 23 patients had atrial shock conversions using the separate shock vector with an average conversion energy of 1.9 ± 1.4  J . (range 0.5–5 J). During follow-up the efficacy of ATP on atrial tachyarrhythmias was 59% and the efficacy of delivered shocks on AF was 85%. This new dual chamber cardioverter defibrillator appropriately detected and classified atrial arrhythmias, and shock therapy for AF was highly effective. The detection algorithm differentiated atrial tachyarrhythmia/AF and did not delay VF detection. The separate shock vector converted induced AF with energies ranging from 0.6 to 5 J. (PACE 2003; 26[Pt. II]:461–465)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9592.2003.00072.x
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  • 6
    Electronic Resource
    Electronic Resource
    Homogeneity and Diameter of Linear Lesions Induced With Multipolar Ablation Catheters: In Vitro and In Vivo Comparison of Pulsed Versus Continuous Radiofrequency Energy Delivery (2000)
    Springer
    Journal of interventional cardiac electrophysiology 4 (2000), S. 655-661 
    Details
    ISSN: 1572-8595
    Keywords: linear lesions ; catheter ablation ; pulsed energy delivery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: For invasive treatment of atrial fibrillation, linear lesions induced with multipolar ablation catheters (MAC) are needed to prevent recurrence. The aim of the study was to compare the efficacy of pulsed versus continuous radiofrequency (RF)-energy delivery using MAC. Methods: In vitro tests were performed using endomyocardial preparations of fresh pig hearts in a 10-liter-bath of physiologic saline solution (37°C) at constant flow conditions (1.5[emsp4 ]l/min). The MAC were placed with a constant pressure of 20 ponds onto the endocardium. The energy (generator: Osypka HAT 200 S) was delivered either pulsed (4 electrodes simultaneously, 5[emsp4 ]ms duty-cycle) or continuously (each electrode separately). In vivo experiments were performed in 6 anesthetized pigs using fluoroscopic positioning of MAC at 40 different intracardial positions and with similar conditions as in vitro experiments. Lesion volume (LV) was calculated after measuring lesion diameter with a microcaliper. The homogeneity of the lesions (LH) was classified from 1–4; with 1 as highest homogeneity. Results: Pulsed energy delivery produced more homogeneous linear lesions in significantly less time. There was no difference in electrode temperature values (50.2±0.8 and 51.3±1.4°C) in vitro and in vivo. In the in vivo experiments, lesion depth and calculated lesion volume were less in both modes of energy delivery but pulsed energy delivery was superior regarding lesion depth and homogeneity. Conclusion: With pulsed energy delivery it is possible to create linear lesions of significantly greater homogeneity. Moreover, larger lesions are induced in less time by pulsed energy delivery in vitro and in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026538204579
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  • 7
    Electronic Resource
    Electronic Resource
    Rezidivierende Synkopen unklarer Genese Diagnostik mittels implantierbaren “Loop”-Recorders (2000)
    Springer
    Medizinische Klinik 95 (2000), S. 578-582 
    Details
    ISSN: 1615-6722
    Keywords: Schlüsselwörter Synkope ; Diagnostik ; “Loop”-Recorder ; Key Words Syncope ; Diagnosis ; Loop recorder
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Background: In about a third of cases of recurrent syncope a diagnosis cannot be established despite extensive cardiovascular and neurologic testing. In patients without underlying heart disease the sensitivity of conventional diagnostic testing is low. Case Report: A 33-year-old male patient underwent implantation of a loop recorder (Reveal®) after negative neurological and cardiovascular testing. One month after implantation sinus node arrest could be documented during a presyncope. The patient underwent pacemaker implantation and remains asymptomatic since then. Conclusion: In patients with syncope and a negative conventional diagnostic workup the implantable loop recorder is a helpful and cost-effective diagnostic tool.
    Notes: Zusammenfassung Hintergrund: Die Diagnostik rezidivierender Synkopen bleibt trotz neurologischer und invasiver kardiologischer Befunderhebung in etwa einem Drittel der Fälle ohne Ergebnis. Insbesondere bei Patienten ohne kardiale Grundkrankheit und ohne Hinweise auf ein Anfallsleiden sind konventionelle diagnostische Methoden wenig sensitiv. Falldarstellung: Einem 33jährigen Patienten mit rezidivierenden Synkopen und umfangreicher negativer neurologischer und kardiologischer Diagnostik wurde ein “Loop”:-Recorder (Reveal®) implantiert. Bereits einen Monat nach Implantation konnte im Rahmen einer Präsynkope ein Sinusarrest mit 3,7 Sekunden Pause aufgezeichnet werden. Daraufhin wurde die Indikation zur Schrittmacherimplantation gestellt, und der Patient ist seitdem symptomfrei. Schlußfolgerung: Bei negativer Synkopendiagnostik stellt der implantierte “Loop”-Recorder eine wertvolle und kosteneffektive Untersuchungsmethode dar.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00002065
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