Home About us Contact
|
Home About us Contact | ||
|
|
||
Pulse Generators (pulse + generators)
Selected AbstractsCardiac Pacing: Memories of a Bygone EraPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 9 2008HARRY G. MOND M.D. The first cardiac pacemaker implants occurred in the late 1950s and involved insertion of epicardial or epimyocardial leads and abdominal pulse generators. By the mid 1960s, cardiologists were making attempts to insert transvenous leads into the right ventricle. These early unipolar leads had large, polished, high polarization electrodes, no fixation device, and no lumen in which to place a stylet for lead positioning. The lead implantation procedures were usually long and the irradiation to both patient and operator excessive. Pulse generators were powered by zinc-mercury cells, which were large, unreliable, and prone to sudden output failure. Postoperative complications such as lead dislodgement, exit block, and premature power source failure were very common with most patients requiring further surgery within a year. Little has been written of this period and in particular the experiences of the operators, such that today's pacemaker implanters have virtually no knowledge of this bygone era. This historical report by four Australian cardiologists details the operative procedures and follow-up management of those original pacemaker recipients. [source] Spinal Cord Stimulation Surgical Technique for the Nonsurgically TrainedNEUROMODULATION, Issue 2009FRCP (C), Marshall D. Bedder MD ABSTRACT The objective of this paper is to educate physicians who implant spinal cord stimulators in current surgical techniques. Many implanters have not gone through formal surgical residencies and learn their surgical techniques during a one year Fellowship or from proctoring experience. This paper utilizes current concepts from the literature to reinforce appropriate surgical practices, which are applicable to surgeons as well as interventional pain physicians. This should be a valuable resource for all Fellows whether they are in surgical programs or pain fellowship programs. In addition, a more detailed presentation is made at the end of this paper on a proposed simple one-incision surgical technique for implantation of small internal pulse generators. This is the first publication in the literature describing such a technique and may be useful for less-experienced implanters, as well as conferring potential advantages in surgical technique. [source] Cardiac Pacing: Memories of a Bygone EraPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 9 2008HARRY G. MOND M.D. The first cardiac pacemaker implants occurred in the late 1950s and involved insertion of epicardial or epimyocardial leads and abdominal pulse generators. By the mid 1960s, cardiologists were making attempts to insert transvenous leads into the right ventricle. These early unipolar leads had large, polished, high polarization electrodes, no fixation device, and no lumen in which to place a stylet for lead positioning. The lead implantation procedures were usually long and the irradiation to both patient and operator excessive. Pulse generators were powered by zinc-mercury cells, which were large, unreliable, and prone to sudden output failure. Postoperative complications such as lead dislodgement, exit block, and premature power source failure were very common with most patients requiring further surgery within a year. Little has been written of this period and in particular the experiences of the operators, such that today's pacemaker implanters have virtually no knowledge of this bygone era. This historical report by four Australian cardiologists details the operative procedures and follow-up management of those original pacemaker recipients. [source] The Salty Dog: Serum Sodium and Potassium Effects on Modern Pacing ElectrodesPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 1 2007RICK McVENES Background: This study was conducted to characterize the behavior of chronic modern endocardial electrodes with capacitively coupled constant voltage pulse generators in canines. Methods: Five animals were studied with chronic paired unipolar microporous platinum, and porous steroid-eluting electrodes in the ventricle. Screw-in and passive fixation electrodes were also implanted in the atrium. IV infusions of 500,800 mL of 50 meq KCl in 500 mL Ringer's solution, and 3% NaCl were given over periods of 120 and 80 minutes, respectively, during separate anesthetized monitors. Results: Mean maximum Na+ and K+ achieved was 158 and 8.3 meq/L, respectively. During KCl infusion, ventricular threshold, current, and energy decreased. In the atrium, half the leads went to exit block at ,7.0 meq/L K+. Others continued to perform acceptably. The atrial electrogram decreased 70% with no change in the ventricular signal. No change in impedance occurred. During NaCl infusion, no changes in atrial or ventricular threshold occurred while current increased 21%,32%. This resulted in a 40%,55% increase in energy due to a 20% decrease in impedance. The atrial electrogram decreased 32%,36% while the ventricular amplitude decreased 25%. Slew rate decreased 19%,27%. Control studies for effects of heart rate, fluid volume, and anesthesia duration did not cause any changes. Conclusion: These data support the conclusion that threshold is a voltage mediated response. Thus, voltage thresholds, not energy, current or pulse duration is the most relevant parameter for safety margin determination. Atrial parameters should be followed during electrolyte imbalances. Correlation in humans is needed. [source] Atrial Evoked Response Integral for Automatic Capture Verification in Atrial PacingPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 1p2 2003GIUSEPPE BORIANI BORIANI, G.,et al.:Atrial Evoked Response Integral for Automatic Capture Verification in Atrial Pacing. Beat-by-beat Autocapture is currently limited to operation in the ventricle with bipolar leads. The authors investigated the integral of the negative-going portion of the atrial evoked response integral (AERI) as a potential resource for verification of atrial capture. Intracardiac electrogram signals were collected from 59 patients (ages 67.8 ± 15.1 years) with bipolar, low polarization atrial leads. The signals were collected over a mean period of 6.1 months (minimum 4 days) after lead implantation. St. Jude Medical Affinity pulse generators were used to perform automatic capture threshold tests while the electrogram signals were recorded by a Model 3510 programming device. These signals were transferred to a personal computer in digital form for later analysis. The AERI was calculated at each programmable pacing voltage until capture was lost. The difference between the polarization integral at loss of capture and evoked response integral with successful capture was sufficient to justify enabling the atrial Autocapture feature in 53 of 59 patients in whom bipolar pacing and unipolar sensing was performed. The authors developed a calibration routine to identify automatically those patients in whom atrial Autocapture could be programmed On, based on the polarization integral at loss of capture, the estimated maximum polarization integral, and the AERI. Preliminary analysis indicated that the AERI is a practical resource for beat-by-beat atrial capture detection when used with low polarization leads. (PACE 2003; 26[Pt. II]:248,252) [source] Variability in Implantable Cardioverter Defibrillator Pulse Generator Longevity Between ManufacturersPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 1p1 2003PATRICK T. ELLINOR ELLINOR, P.T., et al.: Variability in Implantable Cardioverter Defibrillator Pulse Generator Longevity Between Manufacturers.ICDs are used frequently to treat malignant ventricular arrhythmias. Despite the expanding role of these devices, little is known about the manufacturer variability in the performance of ICD generators. The purpose of this study is to explore the indications for ICD pulse generator replacement and to examine performance differences between the three major manufacturers of ICDs in the United States. The authors performed a retrospective review of ICD pulse generators that were implanted and replaced at Massachusetts General Hospital between February 1998 and March 2002. During the study period, 50 (7%) of the 707 devices in the study cohort were replaced. The most common indication for pulse generator replacement was related to battery performance followed by device recall, upgrade to a dual chamber device, and pulse generator malfunction. After exclusion of the recalled devices, a significantly higher number of pulse generators manufactured by St. Jude Medical (14/229) required replacement for battery depletion or prolonged charge times during the study period compared with devices from Guidant (2/220) or Medtronic (0/273),P = 0.003andP < 0.0001, respectively. This difference was attributable to reduced longevity in the Angstrom series of defibrillators. (PACE 2003; 26[Pt. I]:71,75) [source] Clinical Predictors of Defibrillation Thresholds with an Active Pectoral Pulse Generator Lead SystemPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 4 2002DENICE M. HODGSON HODGSON, D.M., et al.: Clinical Predictors of Defibrillation Thresholds with an Active Pectoral Pulse Generator Lead System. Active pectoral pulse generators are used routinely for initial ICD placement because they reduce DFTs and simplify the implantation procedure. Despite the common use of these systems, little is known regarding the clinical predictors of defibrillation efficacy with active pulse generator lead configurations. Such predictors would be helpful to identify patients likely to require higher output devices or more complicated implantations. This was a prospective evaluation of DFT using a uniform testing protocol in 102 consecutive patients with an active pectoral can and dual coil transvenous lead. For each patient, the DFT was measured with a step-down protocol. In addition, 34 parameters were assessed including standard clinical echocardiographic and radiographic measures. Multivariate stepwise regression analysis was performed to identify independent predictors of the DFT. The mean DFT was 9.3 ± 4.6 J and 93% (95/102) of patients had a DFT , 15 J. The QRS duration, interventricular septum thickness, left ventricular mass, and mass index were significant but weak (R < 0.3) univariate predictors of DFT. The left ventricular mass was the only independent predictor by multivariate analysis, but this parameter accounted for < 5% of the variability of DFT measured (adjusted R2= 0.047, P = 0.017). The authors concluded that an acceptable DFT (< 15 J) is observed in > 90% of patients with this dual coil and active pectoral can lead system. Clinical factors are of limited use for predicting DFTs and identifying those patients who will have high thresholds. [source] Runaway Pulse Generator Malfunction Resulting from Undetected Battery DepletionPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 2 2002PUGAZHENDHI VIJAYARAMAN VIJAYARAMAN, P., et al.: Runaway Pulse Generator Malfunction Resulting from Undetected Battery Depletion. Runaway pacemaker is an uncommon, potentially lethal circuit malfunction characterized by sudden onset of erratic pacing at rapid nonphysiological rates. Two patients with a single chamber pacemaker (Medtronic ST 8331 and 8419) presented with episodic dizziness. ECG revealed recurrent decrescendo amplitude episodes of runaway stimuli at 2,400 and 2,600 ppm, approximately 3 seconds in duration, separated by pacing at 62.5 and 65 ppm, respectively. Fortunately the runaway stimuli were subthreshold and did not result in capture of the ventricle. Emergency pulse generator replacement was uneventful. Both leads were normal and both pulse generators had low battery voltages at 1.488 and 1.78 V, respectively. [source] Feasibility and Initial Results of an Internet-Based Pacemaker and ICD Pulse Generator and Lead RegistryPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 1 2001ROBERT HAUSER HAUSER, R., et al.: Feasibility and Initial Results of an Internet-Based Pacemaker and ICD Pulse Generator and Lead Registry. The medical community has no independent source of timely information regarding the performance of pacemaker and ICD pulse generators and leads. Accordingly, the authors established an Internet-based registry of pacemaker and ICD pulse generator and lead failures (www.pacerandicregistry.com). During the first year, they found three previously unreported device problems that were promptly communicated to the participants. Of the failures reported, 11% of ICD and 10% of pacemaker pulse generator failures were heralded by signs other than the expected elective replacement indicator (ERI). Average ICD battery longevity was 4.0 ± 0.7 years, and average dual chamber pacemaker battery longevity was 6.8 ± 2.6 years. Disrupted insulation accounted for 54% of pacemaker and 29% of ICD lead failures. Compared to pacemaker pulse generator and lead failure, ICD device failures were more likely to cause severe clinical consequences. In conclusion, an Internet-based registry is feasible and capable of providing timely data regarding the signs, causes, and clinical consequences of pacemaker and ICD failures. [source] Nanosecond pulsed electric field generators for the study of subcellular effectsBIOELECTROMAGNETICS, Issue 3 2006Juergen F. Kolb Abstract Modeling and experimental studies have shown that pulsed electric fields of nanosecond duration and megavolt per meter amplitude affect subcellular structures but do not lead to the formation of large pores in the outer membrane. This "intracellular electromanipulation" requires the use of pulse generators which provide extremely high power but low energy pulses. In this study, we describe the concept of the required pulsed power sources, their design, operation, and the necessary diagnostics. Two types of pulse generators based on the Blumlein line principle have been developed and are described here. One system is designed to treat a large number of cells in cuvettes holding volumes from 0.1 to 0.8 ml. Pulses of up to 40 kV amplitude, with a duration of 10 ns and a rise time close to 1 ns can be applied to the cuvette. For an electrode gap of 1 mm this voltage corresponds to an average electric field of 40 MV/m. The second system allows for real time observation of individual cells under a microscope. It generates pulses of 10,300 ns duration with a rise time of 3.5 ns and voltage amplitudes up to 1 kV. Connected to a microreactor with an electrode gap of 100 µm, electric fields up to 10 MV/m are applied. Bioelectromagnetics 27:172,187, 2006. © 2005 Wiley-Liss, Inc. [source] | ||||||||||