Semi-rigid single hook localization the best method for localizing ground glass opacities during video-assisted thoracoscopic surgery: re-aerated swine lung experimental and primary clinical results

PubMed Central

Zhao, Guang; Sun, Long; Geng, Guojun; Liu, Hongming; Li, Ning; Liu, Suhuan; Hao, Bing

2017-01-01

Background The aim of this study was to compare the effects of currently available preoperative localization methods, including semi-rigid single hook-wire, double-thorn hook-wire, and microcoil, in localizing the pulmonary nodules, thus to select the best technology to assist video-assisted thoracoscopic surgery (VATS) for small ground glass opacities (GGO). Methods Preoperative CT-guided localizing techniques including semi-rigid single hook-wire, double-thorn hook-wire and microcoil were used in re-aerated fresh swine lung for location experiments. The advantages and drawbacks of the three positioning technologies were compared, and then the most optimal technique was used in patients with GGO. Technical success and post-operative complications were used as primary endpoints. Results All three localizing techniques were successfully performed in the re-aerated fresh swine lung. The median tractive force of semi-rigid single hook wire, double-thorn hook wire and microcoil were 6.5, 4.85 and 0.2 N, which measured by a spring dynamometer. The wound sizes in the superficial pleura, caused by unplugging the needles, were 2 mm in double-thorn hook wire, 1 mm in semi-rigid single hook and 1 mm in microcoil, respectively. In patients with GGOs, the semi-rigid hook wires localizations were successfully performed, without any complication that need to be intervened. Dislodgement was reported in one patient before VATS. No major complications related to the preoperative hook wire localization and VATS were observed. Conclusions We found from our localization experiments in the swine lung that, among the commonly used three localization methods, semi-rigid hook wire showed the best operability and practicability than double-thorn hook wire and microcoil. Preoperative localization of small pulmonary nodules with single semi-rigid hook wire system shows a high success rate, acceptable utility and especially low dislodgement in VATS. PMID:29312722

Biophysically based mathematical modeling of interstitial cells of Cajal slow wave activity generated from a discrete unitary potential basis.

PubMed

Faville, R A; Pullan, A J; Sanders, K M; Koh, S D; Lloyd, C M; Smith, N P

2009-06-17

Spontaneously rhythmic pacemaker activity produced by interstitial cells of Cajal (ICC) is the result of the entrainment of unitary potential depolarizations generated at intracellular sites termed pacemaker units. In this study, we present a mathematical modeling framework that quantitatively represents the transmembrane ion flows and intracellular Ca2+ dynamics from a single ICC operating over the physiological membrane potential range. The mathematical model presented here extends our recently developed biophysically based pacemaker unit modeling framework by including mechanisms necessary for coordinating unitary potential events, such as a T-Type Ca2+ current, Vm-dependent K+ currents, and global Ca2+ diffusion. Model simulations produce spontaneously rhythmic slow wave depolarizations with an amplitude of 65 mV at a frequency of 17.4 cpm. Our model predicts that activity at the spatial scale of the pacemaker unit is fundamental for ICC slow wave generation, and Ca2+ influx from activation of the T-Type Ca2+ current is required for unitary potential entrainment. These results suggest that intracellular Ca2+ levels, particularly in the region local to the mitochondria and endoplasmic reticulum, significantly influence pacing frequency and synchronization of pacemaker unit discharge. Moreover, numerical investigations show that our ICC model is capable of qualitatively replicating a wide range of experimental observations.

[Twiddler's syndrome in a patient with obsessive-compulsive disorder treated with deep brain stimulation].

PubMed

Moliz, Nicolás; Katati, Majed J; Iañez, Benjamín; García, Asunción; Yagui, Eskandar; Horcajadas, Ángel

2015-01-01

Twiddler's syndrome is a rare complication associated with implantable electrical stimulation devices. First described in a patient with a pacemaker, it is a known complication in the field of cardiology. However, it is not so recognised in the world of neurosurgery, in which it has been described in relation to deep brain stimulation (DBS) devices. Characterised by manipulating either consciously or unconsciously the generator of such devices, which causes it to rotate on itself, the syndrome causes the coiling of the wiring of these systems and can lead to their rupture or the displacement of intracranial electrodes. We describe a case of twiddler's syndrome in a patient treated with DBS for obsessive-compulsive disorder, in which clinical deterioration presented after a good initial response. Control radiographs revealed rotation of the wiring system and displacement of the intracranial electrodes. Copyright © 2013 Sociedad Española de Neurocirugía. Published by Elsevier España. All rights reserved.

Biophysically Based Mathematical Modeling of Interstitial Cells of Cajal Slow Wave Activity Generated from a Discrete Unitary Potential Basis

PubMed Central

Faville, R.A.; Pullan, A.J.; Sanders, K.M.; Koh, S.D.; Lloyd, C.M.; Smith, N.P.

2009-01-01

Abstract Spontaneously rhythmic pacemaker activity produced by interstitial cells of Cajal (ICC) is the result of the entrainment of unitary potential depolarizations generated at intracellular sites termed pacemaker units. In this study, we present a mathematical modeling framework that quantitatively represents the transmembrane ion flows and intracellular Ca2+ dynamics from a single ICC operating over the physiological membrane potential range. The mathematical model presented here extends our recently developed biophysically based pacemaker unit modeling framework by including mechanisms necessary for coordinating unitary potential events, such as a T-Type Ca2+ current, Vm-dependent K+ currents, and global Ca2+ diffusion. Model simulations produce spontaneously rhythmic slow wave depolarizations with an amplitude of 65 mV at a frequency of 17.4 cpm. Our model predicts that activity at the spatial scale of the pacemaker unit is fundamental for ICC slow wave generation, and Ca2+ influx from activation of the T-Type Ca2+ current is required for unitary potential entrainment. These results suggest that intracellular Ca2+ levels, particularly in the region local to the mitochondria and endoplasmic reticulum, significantly influence pacing frequency and synchronization of pacemaker unit discharge. Moreover, numerical investigations show that our ICC model is capable of qualitatively replicating a wide range of experimental observations. PMID:19527643

Measuring contraction propagation and localizing pacemaker cells using high speed video microscopy

PubMed Central

Akl, Tony J.; Nepiyushchikh, Zhanna V.; Gashev, Anatoliy A.; Zawieja, David C.; Coté, Gerard L.

2011-01-01

Previous studies have shown the ability of many lymphatic vessels to contract phasically to pump lymph. Every lymphangion can act like a heart with pacemaker sites that initiate the phasic contractions. The contractile wave propagates along the vessel to synchronize the contraction. However, determining the location of the pacemaker sites within these vessels has proven to be very difficult. A high speed video microscopy system with an automated algorithm to detect pacemaker location and calculate the propagation velocity, speed, duration, and frequency of the contractions is presented in this paper. Previous methods for determining the contractile wave propagation velocity manually were time consuming and subject to errors and potential bias. The presented algorithm is semiautomated giving objective results based on predefined criteria with the option of user intervention. The system was first tested on simulation images and then on images acquired from isolated microlymphatic mesenteric vessels. We recorded contraction propagation velocities around 10 mm∕s with a shortening speed of 20.4 to 27.1 μm∕s on average and a contraction frequency of 7.4 to 21.6 contractions∕min. The simulation results showed that the algorithm has no systematic error when compared to manual tracking. The system was used to determine the pacemaker location with a precision of 28 μm when using a frame rate of 300 frames per second. PMID:21361700

A Screening of UNF Targets Identifies Rnb, a Novel Regulator of Drosophila Circadian Rhythms.

PubMed

Kozlov, Anatoly; Jaumouillé, Edouard; Machado Almeida, Pedro; Koch, Rafael; Rodriguez, Joseph; Abruzzi, Katharine C; Nagoshi, Emi

2017-07-12

Behavioral circadian rhythms are controlled by multioscillator networks comprising functionally different subgroups of clock neurons. Studies have demonstrated that molecular clocks in the fruit fly Drosophila melanogaster are regulated differently in clock neuron subclasses to support their specific functions (Lee et al., 2016; Top et al., 2016). The nuclear receptor unfulfilled ( unf ) represents a regulatory node that provides the small ventral lateral neurons (s-LNvs) unique characteristics as the master pacemaker (Beuchle et al., 2012). We previously showed that UNF interacts with the s-LNv molecular clocks by regulating transcription of the core clock gene period ( per ) (Jaumouillé et al., 2015). To gain more insight into the mechanisms by which UNF contributes to the functioning of the circadian master pacemaker, we identified UNF target genes using chromatin immunoprecipitation. Our data demonstrate that a previously uncharacterized gene CG7837 , which we termed R and B ( Rnb ), acts downstream of UNF to regulate the function of the s-LNvs as the master circadian pacemaker. Mutations and LNv-targeted adult-restricted knockdown of Rnb impair locomotor rhythms. RNB localizes to the nucleus, and its loss-of-function blunts the molecular rhythms and output rhythms of the s-LNvs, particularly the circadian rhythms in PDF accumulation and axonal arbor remodeling. These results establish a second pathway by which UNF interacts with the molecular clocks in the s-LNvs and highlight the mechanistic differences in the molecular clockwork within the pacemaker circuit. SIGNIFICANCE STATEMENT Circadian behavior is generated by a pacemaker circuit comprising diverse classes of pacemaker neurons, each of which contains a molecular clock. In addition to the anatomical and functional diversity, recent studies have shown the mechanistic differences in the molecular clockwork among the pacemaker neurons in Drosophila Here, we identified the molecular characteristics distinguishing the s-LNvs, the master pacemaker of the locomotor rhythms, from other clock neuron subtypes. We demonstrated that a newly identified gene Rnb is an s-LNv-specific regulator of the molecular clock and essential for the generation of circadian locomotor behavior. Our results provide additional evidence to the emerging view that the differential regulation of the molecular clocks underlies the functional differences among the pacemaker neuron subgroups. Copyright © 2017 the authors 0270-6474/17/376673-13$15.00/0.

Rapid high-amplitude circumferential slow wave propagation during normal gastric pacemaking and dysrhythmias

PubMed Central

O'Grady, Gregory; Du, Peng; Paskaranandavadivel, Nira; Angeli, Timothy R.; Lammers, Wim JEP; Asirvatham, Samuel J.; Windsor, John A.; Farrugia, Gianrico; Pullan, Andrew J.; Cheng, Leo K.

2012-01-01

Background Gastric slow waves propagate aborally as rings of excitation. Circumferential propagation does not normally occur, except at the pacemaker region. We hypothesized that: i) the unexplained high-velocity, high-amplitude activity associated with the pacemaker region is a consequence of circumferential propagation; ii) rapid, high-amplitude circumferential propagation emerges during gastric dysrhythmias; iii) the driving network conductance might switch between ICC-MP and circular ICC-IM during circumferential propagation; iv) extracellular amplitudes and velocities are correlated. Methods An experimental-theoretical study was performed. HR gastric mapping was performed in pigs during normal activation, pacing and dysrhythmia. Activation profiles, velocities and amplitudes were quantified. ICC pathways were theoretically evaluated in a bidomain model. Extracellular potentials were modelled as a function of membrane potentials. Key Results High-velocity, high-amplitude activation was only recorded in the pacemaker region when circumferential conduction occurred. Circumferential propagation accompanied dysrhythmia in 8/8 experiments, was faster than longitudinal propagation (8.9 vs 6.9 mm/s; p=0.004), and of higher amplitude (739 vs 528 μV; p=0.007). Simulations predicted that ICC-MP could be the driving network during longitudinal propagation, whereas during ectopic pacemaking, ICC-IM could outpace and activate ICC-MP in the circumferential axis. Experimental and modeling data demonstrated a linear relationship between velocities and amplitudes (p<0.001). Conclusions & Inferences The high-velocity and high-amplitude profile of the normal pacemaker region is due to localized circumferential propagation. Rapid circumferential propagation also emerges during a range of gastric dysrhythmias, elevating extracellular amplitudes and organizing transverse wavefronts. One possible explanation for these findings is bidirectional coupling between ICC-MP and circular ICC-IM networks. PMID:22709238

Unpredictable interference of new transcranial motor-evoked potential monitor against the implanted pacemaker.

PubMed

Hayashi, Kazuko

2016-12-01

Recently, NuVasive NV-M5 nerve monitoring system, a new transcranial motor-evoked potential (TcMEP) monitor, has been introduced with the spread of flank-approach spinal operations such as extreme lateral interbody fusion, to prevent nerve damage. Conventional TcMEP monitors use changes in MEP wave patterns, such as amplitude and/or latency, whereas the NV-M5 nerve monitor system first measures the MEP baseline waveform from the transcranial-evoked potential then measures the electric current necessary to obtain the standard of the previous baseline wave pattern at subsequent monitoring times. The NV-M5 monitor determines nerve damage according to the increase in necessary electric current threshold. The NV-M5 monitor also uses a local electrical stimulation mode to monitor the safety of setting screws into the lumbar vertebrae. In this way, various electrical stimulations with various durations and frequencies are used, and electrical noise may result in unpredictable interference with cardiac pacemakers. We performed anesthetic management of extreme lateral interbody fusion surgery using the NV-M5 in a patient with an implanted pacemaker, during which TcMEP stimulation caused interference with the implanted pacemaker. Copyright © 2016 Elsevier Inc. All rights reserved.

From two competing oscillators to one coupled-clock pacemaker cell system

PubMed Central

Yaniv, Yael; Lakatta, Edward G.; Maltsev, Victor A.

2015-01-01

At the beginning of this century, debates regarding “what are the main control mechanisms that ignite the action potential (AP) in heart pacemaker cells” dominated the electrophysiology field. The original theory which prevailed for over 50 years had advocated that the ensemble of surface membrane ion channels (i.e., “M-clock”) is sufficient to ignite rhythmic APs. However, more recent experimental evidence in a variety of mammals has shown that the sarcoplasmic reticulum (SR) acts as a “Ca2+-clock” rhythmically discharges diastolic local Ca2+ releases (LCRs) beneath the cell surface membrane. LCRs activate an inward current (likely that of the Na+/Ca2+ exchanger) that prompts the surface membrane “M-clock” to ignite an AP. Theoretical and experimental evidence has mounted to indicate that this clock “crosstalk” operates on a beat-to-beat basis and determines both the AP firing rate and rhythm. Our review is focused on the evolution of experimental definition and numerical modeling of the coupled-clock concept, on how mechanisms intrinsic to pacemaker cell determine both the heart rate and rhythm, and on future directions to develop further the coupled-clock pacemaker cell concept. PMID:25741284

Monte Carlo simulation to analyze the cost-benefit of radioactive seed localization versus wire localization for breast-conserving surgery in fee-for-service health care systems compared with accountable care organizations.

PubMed

Loving, Vilert A; Edwards, David B; Roche, Kevin T; Steele, Joseph R; Sapareto, Stephen A; Byrum, Stephanie C; Schomer, Donald F

2014-06-01

In breast-conserving surgery for nonpalpable breast cancers, surgical reexcision rates are lower with radioactive seed localization (RSL) than wire localization. We evaluated the cost-benefit of switching from wire localization to RSL in two competing payment systems: a fee-for-service (FFS) system and a bundled payment system, which is typical for accountable care organizations. A Monte Carlo simulation was developed to compare the cost-benefit of RSL and wire localization. Equipment utilization, procedural workflows, and regulatory overhead differentiate the cost between RSL and wire localization. To define a distribution of possible cost scenarios, the simulation randomly varied cost drivers within fixed ranges determined by hospital data, published literature, and expert input. Each scenario was replicated 1000 times using the pseudorandom number generator within Microsoft Excel, and results were analyzed for convergence. In a bundled payment system, RSL reduced total health care cost per patient relative to wire localization by an average of $115, translating into increased facility margin. In an FFS system, RSL reduced total health care cost per patient relative to wire localization by an average of $595 but resulted in decreased facility margin because of fewer surgeries. In a bundled payment system, RSL results in a modest reduction of cost per patient over wire localization and slightly increased margin. A fee-for-service system suffers moderate loss of revenue per patient with RSL, largely due to lower reexcision rates. The fee-for-service system creates a significant financial disincentive for providers to use RSL, although it improves clinical outcomes and reduces total health care costs.

A novel intra-operative, high-resolution atrial mapping approach.

PubMed

Yaksh, Ameeta; van der Does, Lisette J M E; Kik, Charles; Knops, Paul; Oei, Frans B S; van de Woestijne, Pieter C; Bekkers, Jos A; Bogers, Ad J J C; Allessie, Maurits A; de Groot, Natasja M S

2015-12-01

A new technique is demonstrated for extensive high-resolution intra-operative atrial mapping that will facilitate the localization of atrial fibrillation (AF) sources and identification of the substrate perpetuating AF. Prior to the start of extra-corporal circulation, a 8 × 24-electrode array (2-mm inter-electrode distance) is placed subsequently on all the right and left epicardial atrial sites, including Bachmann's bundle, for recording of unipolar electrograms during sinus rhythm and (induced) AF. AF is induced by high-frequency pacing at the right atrial free wall. A pacemaker wire stitched to the right atrium serves as a reference signal. The indifferent pole is connected to a steal wire fixed to subcutaneous tissue. Electrograms are recorded by a computerized mapping system and, after amplification (gain 1000), filtering (bandwidth 0.5-400 Hz), sampling (1 kHz) and analogue to digital conversion (16 bits), automatically stored on hard disk. During the mapping procedure, real-time visualization secures electrogram quality. Analysis will be performed offline. This technique was performed in 168 patients of 18 years and older, with coronary and/or structural heart disease, with or without AF, electively scheduled for cardiac surgery and a ventricular ejection fraction above 40 %. The mean duration of the entire mapping procedure including preparation time was 9 ± 2 min. Complications related to the mapping procedure during or after cardiac surgery were not observed. We introduce the first epicardial atrial mapping approach with a high resolution of ≥1728 recording sites which can be performed in a procedure time of only 9±2 mins. This mapping technique can potentially identify areas responsible for initiation and persistence of AF and hopefully can individualize both diagnosis and therapy of AF.

Breast surgery techniques: preoperative bracketing wire localization by surgeons.

PubMed

Burkholder, Hans C; Witherspoon, Laura E; Burns, R Phillip; Horn, Jeffrey S; Biderman, Michael D

2007-06-01

With the development of expertise in image guidance for breast surgery, many surgeons now perform preoperative wire localization themselves. Use of a single wire versus multiple wires to bracket a radiographic breast abnormality has previously been described, although benefits of this technique based on clinical outcomes such as margin status, tissue volume removed, and re-excision rates have not been established. This study is a retrospective analysis of wire-localized breast biopsies performed by 14 surgeons over 29 months; stereotactic and ultrasound guidance were used. During this time, 489 wire localizations were done, of which 159 used multiple wires. Two hundred eleven of these biopsies were done for malignant disease, 86 using multiple wires. After controlling for tumor node metastases stage, single and multiple wire placements were compared using endpoints of margin status, need for re-excision, and total volume of tissue removed. Neither margin status nor re-excision was related to the number of wires placed. However, the number of wires placed was significantly related to the total volume of tissue removed. Use of more than one localizing wire was associated with greater volume of tissue removal (measured in centimeters cubed) in benign disease (46 vs 25, P < 0.001), equivalent volumes in stage 0 disease (73 vs 67), less volume in stage 1 disease (113 vs 164), and less volume in stages 2 through 4 (158 vs 207, P = 0.03). Outcomes based on surgeon case volume during the study period demonstrated that low- (1-40), medium- (41-80), and high-volume (>80) surgeons did not differ in the type or stage of breast pathology treated. Surgeons with high case volumes were more likely to place multiple localizing wires (P < 0.001) and were more likely to do a breast-conserving procedure if re-excision was performed (P < 0.018). Surgeons with low case volumes were more likely to perform a re-excision (P < 0.025). Surgeon experience has a positive impact on quality outcome measures such as performance of a definitive procedure at the time of initial surgery and use of breast-conserving procedures at the time of re-excision. Multiple wire localization can be used to significantly reduce the volume of breast tissue removed in malignant disease without sacrificing margin status or increasing the need for future re-excision.

Right/left assignment in drift chambers and proportional multiwire chambers (PWC's) using induced signals

DOEpatents

Walenta, Albert H.

1979-01-01

Improved multiwire chamber having means for resolving the left/right ambiguity in the location of an ionizing event. The chamber includes a plurality of spaced parallel anode wires positioned between spaced planar cathodes. Associated with each of the anode wires are a pair of localizing wires, one positioned on either side of the anode wire. The localizing wires are connected to a differential amplifier whose output polarity is determined by whether the ionizing event occurs to the right or left of the anode wire.

Glocal clinical registries: pacemaker registry design and implementation for global and local integration--methodology and case study.

PubMed

da Silva, Kátia Regina; Costa, Roberto; Crevelari, Elizabeth Sartori; Lacerda, Marianna Sobral; de Moraes Albertini, Caio Marcos; Filho, Martino Martinelli; Santana, José Eduardo; Vissoci, João Ricardo Nickenig; Pietrobon, Ricardo; Barros, Jacson V

2013-01-01

The ability to apply standard and interoperable solutions for implementing and managing medical registries as well as aggregate, reproduce, and access data sets from legacy formats and platforms to advanced standard formats and operating systems are crucial for both clinical healthcare and biomedical research settings. Our study describes a reproducible, highly scalable, standard framework for a device registry implementation addressing both local data quality components and global linking problems. We developed a device registry framework involving the following steps: (1) Data standards definition and representation of the research workflow, (2) Development of electronic case report forms using REDCap (Research Electronic Data Capture), (3) Data collection according to the clinical research workflow and, (4) Data augmentation by enriching the registry database with local electronic health records, governmental database and linked open data collections, (5) Data quality control and (6) Data dissemination through the registry Web site. Our registry adopted all applicable standardized data elements proposed by American College Cardiology / American Heart Association Clinical Data Standards, as well as variables derived from cardiac devices randomized trials and Clinical Data Interchange Standards Consortium. Local interoperability was performed between REDCap and data derived from Electronic Health Record system. The original data set was also augmented by incorporating the reimbursed values paid by the Brazilian government during a hospitalization for pacemaker implantation. By linking our registry to the open data collection repository Linked Clinical Trials (LinkedCT) we found 130 clinical trials which are potentially correlated with our pacemaker registry. This study demonstrates how standard and reproducible solutions can be applied in the implementation of medical registries to constitute a re-usable framework. Such approach has the potential to facilitate data integration between healthcare and research settings, also being a useful framework to be used in other biomedical registries.

Pacemaker leads: performance and progress.

PubMed

de Voogt, W G

1999-03-11

Pacing leads remain the "weaker link" of the permanent pacing system. Lead failure has been an issue since the beginning of implantable pacemaker therapy. Modern electronics have brought about considerable progress in pacing technology, but lead design has been slower to evolve and problems persist. IS-1 standardization must be considered a significant advance, but some issues regarding IS-1 standardization persist and have been the cause of some compatibility problems. With respect to lead insulation, silicone has proved to offer total reliability for > 30 years. In the search for better handling characteristics, polyurethane 80A was employed for bipolar leads, but it failed to demonstrate satisfactory insulating properties. New insulation materials, such as ethylene-fluoro-ethylene (ETFE), and coated wire technology look promising, having shown 99.32% survival at 5-year follow-up. Reliability is the main objective in lead design, but leads should provide low battery consumption as well. Low coil resistance, with high electrode impedance in steroid-eluting leads, is the standard at present. Low polarization is a desirable property for 2 main reasons: (1) in conjunction with low-threshold leads, it decreases battery consumption; and (2) it allows capture detection and, therefore, safer pacing at low battery consumption. Lead tip design as well as pacing pulse configuration can influence polarization.

Localized states in an arbitrarily bent quantum wire (bend-imitating approach)

NASA Astrophysics Data System (ADS)

Vakhnenko, Oleksity O.

1996-02-01

The bend-imitating matching technique is proposed to simplify the quantum mechanical treatment of singly and multiply bent 2D quantum wires of constant width, arbitrary bending angles, arbitrary bending radii and arbitrary distances between the bends. The spectrum of one-electron localized states and its dependence on the bending angle and the bending radius in a singly bent wire is explicitly calculated. Doubly bent wires are shown to possess doubly split localized states. The splitting energies as a function of the distance between the bends and the bending angles and bending radii have also been obtained. A similar description of bent 3D quantum wires and bent optical fibers is expected to be possible.

Pre-operative localization of solitary pulmonary nodules with computed tomography-guided hook wire: report of 181 patients.

PubMed

Hanauer, Matthieu; Perentes, Jean Yannis; Krueger, Thorsten; Ris, Hans-Beat; Bize, Pierre; Schmidt, Sabine; Gonzalez, Michel

2016-01-16

Video-assisted thoracic surgery (VATS) is currently performed to diagnose and treat solitary pulmonary nodules (SPN). However, the intra-operative identification of deep nodules can be challenging with VATS as the lung is difficult to palpate. The aim of the study was to report the utility and the results of pre-operative computed tomography (CT)-guided hook wire localization of SPN. All records of the patients undergoing CT-guided hook wire localization prior to VATS resection for SPN between 2002 and 2013 were reviewed. The efficacy in localizing the nodule, hook wire complications, necessity to convert VATS to thoracotomy and the histology of SPN are reported. One hundred eighty-one patients (90 females, mean age 63 y, range 28-82 y) underwent 187 pulmonary resections after CT-guided hook wire localization. The mean SPN diameter was 10.3 mm (range: 4-29 mm). The mean distance of the lesion from the pleural surface was 11.6 mm (range: 0-45 mm). The mean time interval from hook wire insertion to VATS resection was 224 min (range 54-622 min). Hook wire complications included pneumothorax requiring chest tube drainage in 4 patients (2.1%) and mild parenchymal haemorrhage in 11 (5.9%) patients. Migration of the hook wire occurred in 7 patients (3.7%) although it did not affect the success of VATS resection (nodule location guided by the lung puncture site). Three patients underwent additional wedge resection by VATS during the same procedure because no lesion was identified in the surgical specimen. Conversion thoracotomy was required in 13 patients (7 %) for centrally localized lesions (6 patients) and pleural adhesions (7 patients). The mean operative time was 60 min (range 18-135 min). Pathological examination revealed a malignant lesion in 107 patients (59 %). The diagnostic yield was 98.3 %. VATS resection for SPN after CT-guided hook wire localization for SPN is safe and allows for proper diagnosis with a low thoracotomy conversion rate.

Pacemaker syndrome with sub-acute left ventricular systolic dysfunction in a patient with a dual-chamber pacemaker: consequence of lead switch at the header.

PubMed

Khurwolah, Mohammad Reeaze; Vezi, Brian Zwelethini

In the daily practice of pacemaker insertion, the occurrence of atrial and ventricular lead switch at the pacemaker box header is a rare and unintentional phenomenon, with less than five cases reported in the literature. The lead switch may have dire consequences, depending on the indication for the pacemaker. One of these consequences is pacemaker syndrome, in which the normal sequence of atrial and ventricular activation is impaired, leading to sub-optimal ventricular filling and cardiac output. It is important for the attending physician to recognise any worsening of symptoms in a patient who has recently had a permanent pacemaker inserted. In the case of a dual-chamber pacemaker, switching of the atrial and ventricular leads at the pacemaker box header should be strongly suspected. We present an unusual case of pacemaker syndrome and right ventricular-only pacinginduced left ventricular systolic dysfunction in a patient with a dual-chamber pacemaker.

Investigation of the interwire energy transfer of elastic guided waves inside prestressed cables.

PubMed

Treyssède, Fabien

2016-07-01

Elastic guided waves are of interest for the non-destructive evaluation of cables. Cables are most often multi-wire structures, and understanding wave propagation requires numerical models accounting for the helical geometry of individual wires, the interwire contact mechanisms and the effects of prestress. In this paper, a modal approach based on a so-called semi-analytical finite element method and taking advantage of a biorthogonality relation is proposed in order to calculate the forced response under excitation of a cable, multi-wired, twisted, and prestressed. The main goal of this paper is to investigate how the energy transfers from a given wire, directly excited, to the other wires in order to identify some localization of energy inside the active wire as the waves propagate along the waveguide. The power flow of the excited field is theoretically derived and an energy transfer parameter is proposed to evaluate the level of energy localization inside a given wire. Numerical results obtained for different polarizations of excitation, central and peripheral, highlight how the energy may localize, spread, or strongly change in the cross-section as waves travel along the axis. In particular, a compressional mode localized inside the central wire is found, with little dispersion and significant excitability.

Localized corrosion behaviour in simulated human body fluids of commercial Ni-Ti orthodontic wires.

PubMed

Rondelli, G; Vicentini, B

1999-04-01

The corrosion performances in simulated human body fluids of commercial equiatomic Ni-Ti orthodontic wires having various shape and size and produced by different manufacturers were evaluated; for comparison purposes wires made of stainless steel and of cobalt-based alloy were also examined. Potentiodynamic tests in artificial saliva at 40 degrees C indicated a sufficient pitting resistance for the Ni-Ti wires, similar to that of cobalt-based alloy wire; the stainless steel wire, instead, exhibited low pitting potential. Potentiodynamic tests at 40 degrees C in isotonic saline solution (0.9% NaCl) showed, for Ni-Ti and stainless steel wires, pitting potential values in the range approximately 200-400 mV and approximately 350 mV versus SCE, respectively: consequently, according to literature data (Hoar TP, Mears DC. Proc Roy Soc A 1996;294:486-510), these materials should be considered potentially susceptible to pitting; only the cobalt-based alloy should be immune from pitting. The localized corrosion potentials determined in the same environment by the ASTM F746 test (approximately 0-200 mV and 130 mV versus SCE for Ni-Ti and stainless steel, respectively) pointed out that for these materials an even higher risk of localized corrosion. Slight differences in localized corrosion behaviour among the various Ni-Ti wires were detected.

[TRENDS OF PERMANENT PACEMAKER IMPLANTATION IN A SINGLE CENTER OVER A 20-YEAR PERIOD].

PubMed

Antonelli, Dante; Ilan, Limor Bushar; Freedberg, Nahum A; Feldman, Alexander; Turgeman, Yoav

2015-05-01

To review the changes in permanent pacemaker implantation indications, pacing modes and patients' demographics over a 20-year period. We retrospectively retrieved data on patients who underwent first implantation of the pacemaker between 1-1-1991 and 31-12-2010. One thousand and nine (1,009) patients underwent a first pacemaker implantation during that period; 535 were men (53%), their mean age was 74.6±19.5 years; the highest rate of implanted pacemaker was in patients ranging in age from 70-79 years, however there was an increasing number of patients aged over 80 years. The median survival time after initial pacemaker implantation was 8 years. Syncope was the most common symptom (62.5%) and atrioventricular block was the most common electrocardiographic indication (56.4%) leading to pacemaker implantation. There was increased utilization of dual chamber and rate responsive pacemakers over the years. There was no difference regarding mode selection between genders. Pacemaker implantation rates have increased over a 20-year period. Dual chamber replaced most of the single ventricular chamber pacemaker and rate responsive pacemakers became the norm. The data of a small volume center are similar to those reported in pacemaker surveys of high volume pacemaker implantation centers. They confirm adherence to the published guidelines for pacing.

Clinical use of isotope cardiac pacemakers (in German)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wagner, J.; Kreutzberg, B.

1973-01-01

Plutoninm-235 having a half-life of 86.4 yrs has proved suitable as a long-life energy source for a cardiac pacemaker. The radiation dose of this pacemaker is below the I. C. R. P.-recommended values. As the isotope pacemaker costs three times as much as a conventional pacemaker, the merits of implanting an isotope pacemaker vs. the conventional kind are discussed. A survey is given of the cases in which an isotope pacemaker has been used. (GE)

Retrospective Evaluation of Safety, Efficacy and Risk Factors for Pneumothorax in Simultaneous Localizations of Multiple Pulmonary Nodules Using Hook Wire System.

PubMed

Zhong, Yan; Xu, Xiao-Quan; Pan, Xiang-Long; Zhang, Wei; Xu, Hai; Yuan, Mei; Kong, Ling-Yan; Pu, Xue-Hui; Chen, Liang; Yu, Tong-Fu

2017-09-01

To evaluate the safety and efficacy of the hook wire system in the simultaneous localizations for multiple pulmonary nodules (PNs) before video-assisted thoracoscopic surgery (VATS), and to clarify the risk factors for pneumothorax associated with the localization procedure. Between January 2010 and February 2016, 67 patients (147 nodules, Group A) underwent simultaneous localizations for multiple PNs using a hook wire system. The demographic, localization procedure-related information and the occurrence rate of pneumothorax were assessed and compared with a control group (349 patients, 349 nodules, Group B). Multivariate logistic regression analyses were used to determine the risk factors for pneumothorax during the localization procedure. All the 147 nodules were successfully localized. Four (2.7%) hook wires dislodged before VATS procedure, but all these four lesions were successfully resected according to the insertion route of hook wire. Pathological diagnoses were acquired for all 147 nodules. Compared with Group B, Group A demonstrated significantly longer procedure time (p < 0.001) and higher occurrence rate of pneumothorax (p = 0.019). Multivariate logistic regression analysis indicated that position change during localization procedure (OR 2.675, p = 0.021) and the nodules located in the ipsilateral lung (OR 9.404, p < 0.001) were independent risk factors for pneumothorax. Simultaneous localizations for multiple PNs using a hook wire system before VATS procedure were safe and effective. Compared with localization for single PN, simultaneous localizations for multiple PNs were prone to the occurrence of pneumothorax. Position change during localization procedure and the nodules located in the ipsilateral lung were independent risk factors for pneumothorax.

Pacemaker Dependency after Cardiac Surgery: A Systematic Review of Current Evidence.

PubMed

Steyers, Curtis M; Khera, Rohan; Bhave, Prashant

2015-01-01

Severe postoperative conduction disturbances requiring permanent pacemaker implantation frequently occur following cardiac surgery. Little is known about the long-term pacing requirements and risk factors for pacemaker dependency in this population. We performed a systematic review of the literature addressing rates and predictors of pacemaker dependency in patients requiring permanent pacemaker implantation after cardiac surgery. Using a comprehensive search of the Medline, Web of Science and EMBASE databases, studies were selected for review based on predetermined inclusion and exclusion criteria. A total of 8 studies addressing the endpoint of pacemaker-dependency were identified, while 3 studies were found that addressed the recovery of atrioventricular (AV) conduction endpoint. There were 10 unique studies with a total of 780 patients. Mean follow-up ranged from 6-72 months. Pacemaker dependency rates ranged from 32%-91% and recovery of AV conduction ranged from 16%-42%. There was significant heterogeneity with respect to the definition of pacemaker dependency. Several patient and procedure-specific variables were found to be independently associated with pacemaker dependency, but these were not consistent between studies. Pacemaker dependency following cardiac surgery occurs with variable frequency. While individual studies have identified various perioperative risk factors for pacemaker dependency and non-resolution of AV conduction disease, results have been inconsistent. Well-conducted studies using a uniform definition of pacemaker dependency might identify patients who will benefit most from early permanent pacemaker implantation after cardiac surgery.

Procedure times, complication rates, and survival times associated with single-chamber versus dual-chamber pacemaker implantation in dogs with clinical signs of bradyarrhythmia: 54 cases (2004-2009).

PubMed

Genovese, David W; Estrada, Amara H; Maisenbacher, Herbert W; Heatwole, Bonnie A; Powell, Melanie A

2013-01-15

To compare procedure times and major and minor complication rates associated with single-chamber versus dual-chamber pacemaker implantation and with 1-lead, 2-lead, and 3-lead pacemaker implantation in dogs with clinical signs of bradyarrhythmia. Retrospective case series. 54 dogs that underwent pacemaker implantation because of clinical signs of bradyarrhythmia. Medical records of dogs that received pacemakers between July 2004 and December 2009 were reviewed for information regarding signalment, diagnosis, pacemaker implantation, pacemaker type, complications, and survival time. Analyses were performed to determine significant differences in anesthesia time, procedure time, and outcome for dogs on the basis of pacing mode and number of pacing leads. 28 of 54 (51.9%) dogs received single-chamber pacemakers and 26 (48.1%) received dual-chamber pacemakers. Mean ± SD procedural time was significantly longer for patients with dual-chamber pacemakers (133.5 ± 51.3 minutes) than for patients with single-chamber pacemakers (94.9 ± 37.0 minutes), and procedure time increased significantly as the number of leads increased (1 lead, 102.3 ± 51.1 minutes; 2 leads, 114.9 ± 24.8 minutes; 3 leads, 158.2 ± 8.5 minutes). Rates of major and minor complications were not significantly different between dogs that received single-chamber pacemakers and those that received dual-chamber pacemakers or among dogs grouped on the basis of the number of pacing leads placed. Although dual-chamber pacemaker implantation did result in increased procedural and anesthesia times, compared with single-chamber pacemaker implantation, this did not result in a higher complication rate.

21 CFR 870.3640 - Indirect pacemaker generator function analyzer.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Indirect pacemaker generator function analyzer... Indirect pacemaker generator function analyzer. (a) Identification. An indirect pacemaker generator function analyzer is an electrically powered device that is used to determine pacemaker function or...

21 CFR 870.3640 - Indirect pacemaker generator function analyzer.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Indirect pacemaker generator function analyzer... Indirect pacemaker generator function analyzer. (a) Identification. An indirect pacemaker generator function analyzer is an electrically powered device that is used to determine pacemaker function or...

21 CFR 870.3640 - Indirect pacemaker generator function analyzer.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Indirect pacemaker generator function analyzer... Indirect pacemaker generator function analyzer. (a) Identification. An indirect pacemaker generator function analyzer is an electrically powered device that is used to determine pacemaker function or...

21 CFR 870.3640 - Indirect pacemaker generator function analyzer.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Indirect pacemaker generator function analyzer... Indirect pacemaker generator function analyzer. (a) Identification. An indirect pacemaker generator function analyzer is an electrically powered device that is used to determine pacemaker function or...

Permanent Leadless Cardiac Pacemaker Therapy: A Comprehensive Review.

PubMed

Tjong, Fleur V Y; Reddy, Vivek Y

2017-04-11

A new technology, leadless pacemaker therapy, was recently introduced clinically to address lead- and pocket-related complications in conventional transvenous pacemaker therapy. These leadless devices are self-contained right ventricular single-chamber pacemakers implanted by using a femoral percutaneous approach. In this review of available clinical data on leadless pacemakers, early results with leadless devices are compared with historical results with conventional single-chamber pacing. Both presently manufactured leadless pacemakers show similar complications, which are mostly related to the implant procedure: cardiac perforation, device dislocation, and femoral vascular access site complications. In comparison with conventional transvenous single-chamber pacemakers, slightly higher short-term complication rates have been observed: 4.8% for leadless pacemakers versus 4.1% for conventional pacemakers. The complication rate of the leadless pacemakers is influenced by the implanter learning curve for this new procedure. No long-term outcome data are yet available for the leadless pacemakers. Larger leadless pacing trials, with long-term follow-up and direct randomized comparison with conventional pacing systems, will be required to define the proper clinical role of these leadless systems. Although current leadless pacemakers are limited to right ventricular pacing, future advanced, communicating, multicomponent systems are expected to expand the potential benefits of leadless therapy to a larger patient population. © 2017 American Heart Association, Inc.

SPM local oxidation nanolithography with active control of cantilever dynamics

NASA Astrophysics Data System (ADS)

Nishimura, S.; Takemura, Y.; Shirakashi, J.

2007-04-01

Local oxidation nanolithography using scanning probe microscope (SPM) has enabled us to fabricate nanometer-scale oxide wires on material surfaces. Here, we study tapping mode SPM local oxidation experiments for silicon by controlling the dynamic properties of the cantilever. Dependence of feature size of fabricated oxide wires on the amplitude of the cantilever was precisely investigated. The quality factor (Q) was fixed at a natural value of ~500. By enhancing the amplitude of the cantilever, both width and height of fabricated Si oxide wires were decreased. With the variation of the amplitude of the cantilever from 0.5 V to 3.0 V (DC voltage = 22.5 V, scanning speed = 20 nm/s), the feature size of Si oxide wires was well controlled, ranging from 40 nm to 18 nm in width and 2.3 nm to 0.6 nm in height. Standard deviation of width on Si oxide wires formed by tapping mode SPM is around 2.0 nm, which is smaller than that of contact mode Si oxide wires. Furthermore, the variation of the oscillation amplitude of the cantilever does not affect the size uniformity of the wires. These results imply that the SPM local oxidation nanolithography with active control of cantilever dynamics is a useful technique for producing higher controllability on the nanometer-scale fabrication of Si oxide wires.

21 CFR 870.3620 - Pacemaker lead adaptor.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Pacemaker lead adaptor. 870.3620 Section 870.3620...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3620 Pacemaker lead adaptor. (a) Identification. A pacemaker lead adaptor is a device used to adapt a pacemaker lead so that it...

21 CFR 870.3620 - Pacemaker lead adaptor.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Pacemaker lead adaptor. 870.3620 Section 870.3620...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3620 Pacemaker lead adaptor. (a) Identification. A pacemaker lead adaptor is a device used to adapt a pacemaker lead so that it...

21 CFR 870.3620 - Pacemaker lead adaptor.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Pacemaker lead adaptor. 870.3620 Section 870.3620...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3620 Pacemaker lead adaptor. (a) Identification. A pacemaker lead adaptor is a device used to adapt a pacemaker lead so that it...

21 CFR 870.3610 - Implantable pacemaker pulse generator.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Implantable pacemaker pulse generator. 870.3610... pacemaker pulse generator. (a) Identification. An implantable pacemaker pulse generator is a device that has... implantable pacemaker pulse generator device that was in commercial distribution before May 28, 1976, or that...

21 CFR 870.3620 - Pacemaker lead adaptor.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Pacemaker lead adaptor. 870.3620 Section 870.3620...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3620 Pacemaker lead adaptor. (a) Identification. A pacemaker lead adaptor is a device used to adapt a pacemaker lead so that it...

21 CFR 870.3610 - Implantable pacemaker pulse generator.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Implantable pacemaker pulse generator. 870.3610... pacemaker pulse generator. (a) Identification. An implantable pacemaker pulse generator is a device that has... implantable pacemaker pulse generator device that was in commercial distribution before May 28, 1976, or that...

Racing of the biological pacemaker.

PubMed

Yu, Han-Gang

2009-01-01

Over the past decade, rapid progress in the molecular studies of cardiac ion channels and stem cells biology has led to efforts to create a biological pacemaker to supplement the widely-used electronic pacemaker. We will review the main concepts of cardiac pacemaker activities in different heart regions and the approaches to design a working biological pacemaker. We will focus on how to use the gene- and cell-based approaches to meet the requirements of a working biological pacemaker. Possible future development and precautions for creation of an effective biological pacemaker superior to the electronic counterpart are also discussed along with recent patents.

Pacemaker Dependency after Cardiac Surgery: A Systematic Review of Current Evidence

PubMed Central

2015-01-01

Background Severe postoperative conduction disturbances requiring permanent pacemaker implantation frequently occur following cardiac surgery. Little is known about the long-term pacing requirements and risk factors for pacemaker dependency in this population. Methods We performed a systematic review of the literature addressing rates and predictors of pacemaker dependency in patients requiring permanent pacemaker implantation after cardiac surgery. Using a comprehensive search of the Medline, Web of Science and EMBASE databases, studies were selected for review based on predetermined inclusion and exclusion criteria. Results A total of 8 studies addressing the endpoint of pacemaker-dependency were identified, while 3 studies were found that addressed the recovery of atrioventricular (AV) conduction endpoint. There were 10 unique studies with a total of 780 patients. Mean follow-up ranged from 6–72 months. Pacemaker dependency rates ranged from 32%-91% and recovery of AV conduction ranged from 16%-42%. There was significant heterogeneity with respect to the definition of pacemaker dependency. Several patient and procedure-specific variables were found to be independently associated with pacemaker dependency, but these were not consistent between studies. Conclusions Pacemaker dependency following cardiac surgery occurs with variable frequency. While individual studies have identified various perioperative risk factors for pacemaker dependency and non-resolution of AV conduction disease, results have been inconsistent. Well-conducted studies using a uniform definition of pacemaker dependency might identify patients who will benefit most from early permanent pacemaker implantation after cardiac surgery. PMID:26470027

Analysis of a five year experience of permanent pacemaker implantation at a Nigerian Teaching Hospital: need for a national database

PubMed Central

Falase, Bode; Sanusi, Michael; Johnson, Adeyemi; Akinrinlola, Fola; Ajayi, Reina; Oke, David

2013-01-01

Introduction Permanent pacemaker implantation is available in Nigeria. There is however no national registry or framework for pacemaker data collection. A pacemaker database has been developed in our institution and the results are analyzed in this study. Methods The study period was between January 2008 and December 2012. Patient data was extracted from a prospectively maintained database which was designed to include the fields of the European pacemaker patient identification code. Results Of the 51 pacemaker implants done, there were 29 males (56.9%) and 22 females (43.1%). Mean age was 68.2±12.7 years. Clinical indications were syncopal attacks in 25 patients (49%), dizzy spells in 15 patients (29.4%), bradycardia with no symptoms in 10 patients (17.7%) and dyspnoea in 2 patients (3.9%). The ECG diagnosis was complete heart block in 27 patients (53%), second degree heart block in 19 patients (37.2%) and sick sinus syndrome with bradycardia in 5 patients (9.8%). Pacemaker modes used were ventricular pacing in 29 patients (56.9%) and dual chamber pacing in 22 patients (43.1%). Files have been closed in 20 patients (39.2%) and 31 patients (60.8%) are still being followed up with median follow up of 26 months, median of 5 visits and 282 pacemaker checks done. Complications seen during follow up were 3 lead displacements (5.9%), 3 pacemaker infections (5.9%), 2 pacemaker pocket erosions (3.9%), and 1 pacemaker related death (2%). There were 5 non-pacemaker related deaths (9.8%). Conclusion Pacemaker data has been maintained for 5 years. We urge other implanting institutions in Nigeria to maintain similar databases and work towards establishment of a national pacemaker registry. PMID:24498465

The mammalian retina as a clock

NASA Technical Reports Server (NTRS)

Tosini, Gianluca; Fukuhara, Chiaki

2002-01-01

Many physiological, cellular, and biochemical parameters in the retina of vertebrates show daily rhythms that, in many cases, also persist under constant conditions. This demonstrates that they are driven by a circadian pacemaker. The presence of an autonomous circadian clock in the retina of vertebrates was first demonstrated in Xenopus laevis and then, several years later, in mammals. In X. laevis and in chicken, the retinal circadian pacemaker has been localized in the photoreceptor layer, whereas in mammals, such information is not yet available. Recent advances in molecular techniques have led to the identification of a group of genes that are believed to constitute the molecular core of the circadian clock. These genes are expressed in the retina, although with a slightly different 24-h profile from that observed in the central circadian pacemaker. This result suggests that some difference (at the molecular level) may exist between the retinal clock and the clock located in the suprachiasmatic nuclei of hypothalamus. The present review will focus on the current knowledge of the retinal rhythmicity and the mechanisms responsible for its control.

Network properties of interstitial cells of Cajal affect intestinal pacemaker activity and motor patterns, according to a mathematical model of weakly coupled oscillators.

PubMed

Wei, Ruihan; Parsons, Sean P; Huizinga, Jan D

2017-03-01

What is the central question of this study? What are the effects of interstitial cells of Cajal (ICC) network perturbations on intestinal pacemaker activity and motor patterns? What is the main finding and its importance? Two-dimensional modelling of the ICC pacemaker activity according to a phase model of weakly coupled oscillators showed that network properties (coupling strength between oscillators, frequency gradient and frequency noise) strongly influence pacemaker network activity and subsequent motor patterns. The model explains motor patterns observed in physiological conditions and provides predictions and testable hypotheses for effects of ICC loss and frequency modulation on the motor patterns. Interstitial cells of Cajal (ICC) are the pacemaker cells of gut motility and are associated with motility disorders. Interstitial cells of Cajal form a network, but the contributions of its network properties to gut physiology and dysfunction are poorly understood. We modelled an ICC network as a two-dimensional network of weakly coupled oscillators with a frequency gradient and showed changes over time in video and graphical formats. Model parameters were obtained from slow-wave-driven contraction patterns in the mouse intestine and pacemaker slow-wave activities from the cat intestine. Marked changes in propagating oscillation patterns (including changes from propagation to non-propagating) were observed by changing network parameters (coupling strength between oscillators, the frequency gradient and frequency noise), which affected synchronization, propagation velocity and occurrence of dislocations (termination of an oscillation). Complete uncoupling of a circumferential ring of oscillators caused the proximal and distal section to desynchronize, but complete synchronization was maintained with only a single oscillator connecting the sections with high enough coupling. The network of oscillators could withstand loss; even with 40% of oscillators lost randomly within the network, significant synchronization and anterograde propagation remained. A local increase in pacemaker frequency diminished anterograde propagation; the effects were strongly dependent on location, frequency gradient and coupling strength. In summary, the model puts forth the hypothesis that fundamental changes in oscillation patterns (ICC slow-wave activity or circular muscle contractions) can occur through physiological modulation of network properties. Strong evidence is provided to accept the ICC network as a system of coupled oscillators. © 2016 The Authors. Experimental Physiology © 2016 The Physiological Society.

Electrical interference in non-competitive pacemakers

PubMed Central

Sowton, E.; Gray, K.; Preston, T.

1970-01-01

Patients with 41 implanted non-competitive pacemakers were investigated. A variety of domestic electrical equipment, a motor-car, and a physiotherapy diathermy apparatus were each operated in turn at various ranges from the patient. Interference effects on pacemaker function were assessed on the electrocardiograph. Medtronic demand 5841 pacemakers were stopped by diathermy while Cordis Ectocor pacemakers developed a fast discharge rate. Cordis triggered pacemakers (both Atricor and Ectocor) were sensitive to interference from many items of domestic equipment and the motor car. The Elema EM153 ran at an increased rate when an electric razor was running close to the pacemaker. The Devices demand 2980 and the Medtronic demand 5841 were not affected by the domestic equipment tested. The significance of interference effects is discussed in relation to pacemaker design. Images PMID:5470044

An optically coupled system for quantitative monitoring of MRI-induced RF currents into long conductors.

PubMed

Zanchi, Marta G; Venook, Ross; Pauly, John M; Scott, Greig C

2010-01-01

The currents induced in long conductors such as guidewires by the radio-frequency (RF) field in magnetic resonance imaging (MRI) are responsible for potentially dangerous heating of surrounding media, such as tissue. This paper presents an optically coupled system with the potential to quantitatively measure the RF currents induced on these conductors. The system uses a self shielded toroid transducer and active circuitry to modulate a high speed light-emitting-diode transmitter. Plastic fiber guides the light to a photodiode receiver and transimpedance amplifier. System validation included a series of experiments with bare wires that compared wire tip heating by fluoroptic thermometers with the RF current sensor response. Validations were performed on a custom whole body 64 MHz birdcage test platform and on a 1.5 T MRI scanner. With this system, a variety of phenomena were demonstrated including cable trap current attenuation, lossy dielectric Q-spoiling and even transverse electromagnetic wave node patterns. This system should find applications in studies of MRI RF safety for interventional devices such as pacemaker leads, and guidewires. In particular, variations of this device could potentially act as a realtime safety monitor during MRI guided interventions.

Initial experience with remote magnetic navigation for left ventricular lead placement.

PubMed

Mischke, Karl; Knackstedt, Christian; Schmid, Michael; Hatam, Nima; Becker, Michael; Spillner, Jan; Fache, Kerstin; Kelm, Malte; Schauerte, Patrick

2009-08-01

A novel magnetic navigation system allows remote steering of guidewires and catheters. This system may be used for left ventricular lead placement for cardiac resynchronization therapy (CRT). We sought to evaluate the feasibility and safety of magnetic guidewire navigation for CRT procedures. 123 consecutive patients underwent CRT implantation/revision procedures (including pacemaker upgrades in n=22 and left ventricular lead placement after dislocation in n=4 patients). Left ventricular lead placement in a coronary sinus side branch was performed either conventionally or using magnetic navigation. The magnetic navigation system (Niobe) consists of two permanent magnets creating a steerable magnetic field. Guidewires with integrated magnets align to the magnetic field and were used for over-the-wire implantation of pacemaker leads in the coronary sinus. Patients were assigned to conventional (n=93) or magnetic (n=30) navigation according to room availability. Venography of the coronary venous system was performed to select a target vessel for lead implantation. Guidewire access to the target vessel was achieved in 100% using magnetic navigation compared to 87% with the conventional approach (P < 0.05). Implantation success rates, total procedure and fluoroscopy times did not differ significantly between groups. No periprocedural death and no intraoperative device dysfunction occurred in either group.The magnetic guidewire ruptured in one patient. Left ventricular lead placement using magnetic guidewire navigation to engage the desired coronary sinus side branch can be successfully performed for CRT.

Glocal Clinical Registries: Pacemaker Registry Design and Implementation for Global and Local Integration – Methodology and Case Study

PubMed Central

da Silva, Kátia Regina; Costa, Roberto; Crevelari, Elizabeth Sartori; Lacerda, Marianna Sobral; de Moraes Albertini, Caio Marcos; Filho, Martino Martinelli; Santana, José Eduardo; Vissoci, João Ricardo Nickenig; Pietrobon, Ricardo; Barros, Jacson V.

2013-01-01

Background The ability to apply standard and interoperable solutions for implementing and managing medical registries as well as aggregate, reproduce, and access data sets from legacy formats and platforms to advanced standard formats and operating systems are crucial for both clinical healthcare and biomedical research settings. Purpose Our study describes a reproducible, highly scalable, standard framework for a device registry implementation addressing both local data quality components and global linking problems. Methods and Results We developed a device registry framework involving the following steps: (1) Data standards definition and representation of the research workflow, (2) Development of electronic case report forms using REDCap (Research Electronic Data Capture), (3) Data collection according to the clinical research workflow and, (4) Data augmentation by enriching the registry database with local electronic health records, governmental database and linked open data collections, (5) Data quality control and (6) Data dissemination through the registry Web site. Our registry adopted all applicable standardized data elements proposed by American College Cardiology / American Heart Association Clinical Data Standards, as well as variables derived from cardiac devices randomized trials and Clinical Data Interchange Standards Consortium. Local interoperability was performed between REDCap and data derived from Electronic Health Record system. The original data set was also augmented by incorporating the reimbursed values paid by the Brazilian government during a hospitalization for pacemaker implantation. By linking our registry to the open data collection repository Linked Clinical Trials (LinkedCT) we found 130 clinical trials which are potentially correlated with our pacemaker registry. Conclusion This study demonstrates how standard and reproducible solutions can be applied in the implementation of medical registries to constitute a re-usable framework. Such approach has the potential to facilitate data integration between healthcare and research settings, also being a useful framework to be used in other biomedical registries. PMID:23936257

Computer algorithms for automated detection and analysis of local Ca2+ releases in spontaneously beating cardiac pacemaker cells

PubMed Central

Kim, Mary S.; Tsutsui, Kenta; Stern, Michael D.; Lakatta, Edward G.; Maltsev, Victor A.

2017-01-01

Local Ca2+ Releases (LCRs) are crucial events involved in cardiac pacemaker cell function. However, specific algorithms for automatic LCR detection and analysis have not been developed in live, spontaneously beating pacemaker cells. In the present study we measured LCRs using a high-speed 2D-camera in spontaneously contracting sinoatrial (SA) node cells isolated from rabbit and guinea pig and developed a new algorithm capable of detecting and analyzing the LCRs spatially in two-dimensions, and in time. Our algorithm tracks points along the midline of the contracting cell. It uses these points as a coordinate system for affine transform, producing a transformed image series where the cell does not contract. Action potential-induced Ca2+ transients and LCRs were thereafter isolated from recording noise by applying a series of spatial filters. The LCR birth and death events were detected by a differential (frame-to-frame) sensitivity algorithm applied to each pixel (cell location). An LCR was detected when its signal changes sufficiently quickly within a sufficiently large area. The LCR is considered to have died when its amplitude decays substantially, or when it merges into the rising whole cell Ca2+ transient. Ultimately, our algorithm provides major LCR parameters such as period, signal mass, duration, and propagation path area. As the LCRs propagate within live cells, the algorithm identifies splitting and merging behaviors, indicating the importance of locally propagating Ca2+-induced-Ca2+-release for the fate of LCRs and for generating a powerful ensemble Ca2+ signal. Thus, our new computer algorithms eliminate motion artifacts and detect 2D local spatiotemporal events from recording noise and global signals. While the algorithms were developed to detect LCRs in sinoatrial nodal cells, they have the potential to be used in other applications in biophysics and cell physiology, for example, to detect Ca2+ wavelets (abortive waves), sparks and embers in muscle cells and Ca2+ puffs and syntillas in neurons. PMID:28683095

Stabilization of diastolic calcium signal via calcium pump regulation of complex local calcium releases and transient decay in a computational model of cardiac pacemaker cell with individual release channels

PubMed Central

Maltsev, Alexander V.; Maltsev, Victor A.; Stern, Michael D.

2017-01-01

Intracellular Local Ca releases (LCRs) from sarcoplasmic reticulum (SR) regulate cardiac pacemaker cell function by activation of electrogenic Na/Ca exchanger (NCX) during diastole. Prior studies demonstrated the existence of powerful compensatory mechanisms of LCR regulation via a complex local cross-talk of Ca pump, release and NCX. One major obstacle to study these mechanisms is that LCR exhibit complex Ca release propagation patterns (including merges and separations) that have not been characterized. Here we developed new terminology, classification, and computer algorithms for automatic detection of numerically simulated LCRs and examined LCR regulation by SR Ca pumping rate (Pup) that provides a major contribution to fight-or-flight response. In our simulations the faster SR Ca pumping accelerates action potential-induced Ca transient decay and quickly clears Ca under the cell membrane in diastole, preventing premature releases. Then the SR generates an earlier, more synchronized, and stronger diastolic LCR signal activating an earlier and larger inward NCX current. LCRs at higher Pup exhibit larger amplitudes and faster propagation with more collisions to each other. The LCRs overlap with Ca transient decay, causing an elevation of the average diastolic [Ca] nadir to ~200 nM (at Pup = 24 mM/s). Background Ca (in locations lacking LCRs) quickly decays to resting Ca levels (<100 nM) at high Pup, but remained elevated during slower decay at low Pup. Release propagation is facilitated at higher Pup by a larger LCR amplitude, whereas at low Pup by higher background Ca. While at low Pup LCRs show smaller amplitudes, their larger durations and sizes combined with longer transient decay stabilize integrals of diastolic Ca and NCX current signals. Thus, the local interplay of SR Ca pump and release channels regulates LCRs and Ca transient decay to insure fail-safe pacemaker cell operation within a wide range of rates. PMID:28792496

Effects of 60-Heartz electric and magnetic fields on implanted cardiac pacemakers. Final report. [Hazards of power transmission line frequencies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bridges, J.E.; Frazier, M.J.

1979-09-01

The effects of 60-Hz electric and magnetic fields of exta-high voltage (EHV) transmission lines on the performance of implanted cardiac pacemakers were studied by: (1) in vitro bench tests of a total of thirteen cardiac pacemakers; (2) in vivo tests of six implanted cardiac pacemakers in baboons; and (3) non-hazardous skin measurement tests on four humans. Analytical methods were developed to predict the thresholds of body current and electric fields capable of affecting normal pacemaker operation in humans. The field strengths calculated to alter implanted pacemaker performance were compared with the range of maximum electric and magnetic field strengths amore » human would normally encounter under transmission lines of various voltages. Results indicate that the electric field or body current necessary to alter the normal operation of pacemakers is highly dependent on the type of pacemaker and the location of the implanted electrodes. However, cardiologists have not so far detected harmful effects of pacemaker reversion to the asynchronous mode in current types of pacemakers and with present methods of implantation. Such interferences can be eliminated by using advanced pacemakers less sensitive to 60-Hz voltages or by using implantation lead arrangements less sensitive to body current.« less

Pacemaker Use Following Heart Transplantation

PubMed Central

Mallidi, Hari R.; Bates, Michael

2017-01-01

Background: The incidence of permanent pacemaker implantation after orthotopic heart transplantation has been reported to be 2%-24%. Transplanted hearts usually exhibit sinus rhythm in the operating room following reperfusion, and most patients do not exhibit significant arrhythmias during the postoperative period. However, among the patients who do exhibit abnormalities, pacemakers may be implanted for early sinus node dysfunction but are rarely used after 6 months. Permanent pacing is often required for atrioventricular block. A different cohort of transplant patients presents later with bradycardia requiring pacemaker implantation, reported to occur in approximately 1.5% of patients. The objectives of this study were to investigate the indications for pacemaker implantation, compare the need for pacemakers following bicaval vs biatrial anastomosis, and examine the long-term outcomes of heart transplant patients who received pacemakers. Methods: For this retrospective, case-cohort, single-institution study, patients were identified from clinical research and administrative transplant databases. Information was supplemented with review of the medical records. Standard statistical techniques were used, with chi-square testing for categorical variables and the 2-tailed t test for continuous variables. Survival was compared with the use of log-rank methods. Results: Between January 1968 and February 2008, 1,450 heart transplants were performed at Stanford University. Eighty-four patients (5.8%) were identified as having had a pacemaker implanted. Of these patients, 65.5% (55) had the device implanted within 30 days of transplantation, and 34.5% (29) had late implantation. The mean survival of patients who had an early pacemaker implant was 6.4 years compared to 7.7 years for those with a late pacemaker implant (P<0.05). Sinus node dysfunction and heart block were the most common indications for pacemaker implantation. Starting in 1997, a bicaval technique was used for implantation. The incidence of pacemaker implantation by technique was 2.0% for bicaval and 9.1% for biatrial (P=0.001). Significantly more rejection episodes occurred in the pacemaker group (2.67 ± 2.18) compared with the no-pacemaker group (2.01 ± 2.05) (P<0.05). Conclusion: Our results show a decreased pacemaker need after bicaval anastomosis and that more patients who needed a pacemaker after transplantation had a pretransplant diagnosis of ischemic cardiomyopathy. In our cohort, the need for a permanent pacemaker was also associated with older donor grafts and an increase in the number of treated rejection episodes. PMID:28331443

[Wide QRS tachycardia preceded by pacemaker spikes].

PubMed

Romero, M; Aranda, A; Gómez, F J; Jurado, A

2014-04-01

The differential diagnosis and therapeutic management of wide QRS tachycardia preceded by pacemaker spike is presented. The pacemaker-mediated tachycardia, tachycardia fibrillo-flutter in patients with pacemakers, and runaway pacemakers, have a similar surface electrocardiogram, but respond to different therapeutic measures. The tachycardia response to the application of a magnet over the pacemaker could help in the differential diagnosis, and in some cases will be therapeutic, as in the case of a tachycardia-mediated pacemaker. Although these conditions are diagnosed and treated in hospitals with catheterization laboratories using the application programmer over the pacemaker, patients presenting in primary care clinic and emergency forced us to make a diagnosis and treat the haemodynamically unstable patient prior to referral. Copyright © 2012 Sociedad Española de Médicos de Atención Primaria (SEMERGEN). Publicado por Elsevier España. All rights reserved.

Radiation induced failures of complementary metal oxide semiconductor containing pacemakers: a potentially lethal complication

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lewin, A.A.; Serago, C.F.; Schwade, J.G.

1984-10-01

New multi-programmable pacemakers frequently employ complementary metal oxide semiconductors (CMOS). This circuitry appears more sensitive to the effects of ionizing radiation when compared to the semiconductor circuits used in older pacemakers. A case of radiation induced runaway pacemaker in a CMOS device is described. Because of this and other recent reports of radiation therapy-induced CMOS type pacemaker failure, these pacemakers should not be irradiated. If necessary, the pacemaker can be shielded or moved to a site which can be shielded before institution of radiation therapy. This is done to prevent damage to the CMOS circuit and the life threatening arrythmiasmore » which may result from such damage.« less

Sacral neuromodulation and cardiac pacemakers.

PubMed

Roth, Ted M

2010-08-01

Potential for cross-talk between cardiac pacemakers and sacral neuromodulation remains speculative. We present a case series of patients with cardiac pacemakers who underwent staged Interstim (Medtronic, Minneapolis, MN) implantation and patients who had pulse generator implantation who later required cardiac pacemakers. No cross-talk was demonstrated in either group. Sacral neuromodulation appears to be safe in the setting of cardiac pacemakers without cardioversion/defibrillation technology.

On the Evolution of the Cardiac Pacemaker

PubMed Central

Burkhard, Silja; van Eif, Vincent; Garric, Laurence; Christoffels, Vincent M.; Bakkers, Jeroen

2017-01-01

The rhythmic contraction of the heart is initiated and controlled by an intrinsic pacemaker system. Cardiac contractions commence at very early embryonic stages and coordination remains crucial for survival. The underlying molecular mechanisms of pacemaker cell development and function are still not fully understood. Heart form and function show high evolutionary conservation. Even in simple contractile cardiac tubes in primitive invertebrates, cardiac function is controlled by intrinsic, autonomous pacemaker cells. Understanding the evolutionary origin and development of cardiac pacemaker cells will help us outline the important pathways and factors involved. Key patterning factors, such as the homeodomain transcription factors Nkx2.5 and Shox2, and the LIM-homeodomain transcription factor Islet-1, components of the T-box (Tbx), and bone morphogenic protein (Bmp) families are well conserved. Here we compare the dominant pacemaking systems in various organisms with respect to the underlying molecular regulation. Comparative analysis of the pathways involved in patterning the pacemaker domain in an evolutionary context might help us outline a common fundamental pacemaker cell gene programme. Special focus is given to pacemaker development in zebrafish, an extensively used model for vertebrate development. Finally, we conclude with a summary of highly conserved key factors in pacemaker cell development and function. PMID:29367536

Dosimetric perturbations due to an implanted cardiac pacemaker in MammoSite{sup Registered-Sign} treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sung, Wonmo; Kim, Siyong; Kim, Jung-in

2012-10-15

Purpose: To investigate dose perturbations for pacemaker-implanted patients in partial breast irradiation using high dose rate (HDR) balloon brachytherapy. Methods: Monte Carlo (MC) simulations were performed to calculate dose distributions involving a pacemaker in Ir-192 HDR balloon brachytherapy. Dose perturbations by varying balloon-to-pacemaker distances (BPD = 50 or 100 mm) and concentrations of iodine contrast medium (2.5%, 5.0%, 7.5%, and 10.0% by volume) in the balloon were investigated for separate parts of the pacemaker (i.e., battery and substrate). Relative measurements using an ion-chamber were also performed to confirm MC results. Results: The MC and measured results in homogeneous media withoutmore » a pacemaker agreed with published data within 2% from the balloon surface to 100 mm BPD. Further their dose distributions with a pacemaker were in a comparable agreement. The MC results showed that doses over the battery were increased by a factor of 3, compared to doses without a pacemaker. However, there was no significant dose perturbation in the middle of substrate but up to 70% dose increase in the substrate interface with the titanium capsule. The attenuation by iodine contrast medium lessened doses delivered to the pacemaker by up to 9%. Conclusions: Due to inhomogeneity of pacemaker and contrast medium as well as low-energy photons in Ir-192 HDR balloon brachytherapy, the actual dose received in a pacemaker is different from the homogeneous medium-based dose and the external beam-based dose. Therefore, the dose perturbations should be considered for pacemaker-implanted patients when evaluating a safe clinical distance between the balloon and pacemaker.« less

Impact of pacemaker mode in patients with atrioventricular conduction disturbance after trans-catheter aortic valve implantation.

PubMed

Takahashi, Masao; Badenco, Nicolas; Monteau, Jacques; Gandjbakhch, Estelle; Extramiana, Fabrice; Urena, Marina; Karam, Nicole; Marijon, Eloi; Algalarrondo, Vincent; Teiger, Emmanuel; Lellouche, Nicolas

2018-03-14

This study aimed to assess the impact of pacemaker mode programming on clinical outcomes in patients with high-degree atrioventricular conduction disturbance (AVCD) after transcatheter aortic valve implantation (TAVI). Although high-degree AVCD after TAVI can receive pacemaker, recovery of the AVCD is often observed. Specific pacemaker algorithms (AAI-DDD mode switch) are available which favor spontaneous atrioventricular conduction. Of 1,621 consecutive multi-center TAVI patients, 269 (16.4%) received pacemaker. We retrospectively included 91 patients with persistent high-degree AVCD at hospital discharge. Pacemaker dependency was defined as absence, inadequate intrinsic ventricular rhythm, or ventricular pacing time > 95% on pacemaker interrogation during follow-up. Comparison of heart failure hospitalization and death between conventional DDD (cDDD) and other modes was examined (AAI-DDD and VVI). During a mean follow-up duration of 13 months, the pacemaker dependency rate was 52.8%. Patients with cDDD mode (N = 36: 40.0%) had significantly more pacemaker dependency. Multivariate analysis showed that cDDD mode was independently associated with pacemaker dependency (odds ratio = 3.63, P = 0.03). Moreover, cDDD patients had a significant higher incidence of heart failure hospitalization (Hospitalization: cDDD vs. others = 45.4% vs. 18.2%, P = 0.03) and had a higher incidence of mortality (Death: cDDD vs. the others = 27.0% vs. 4.4%, P = 0.06). Up to half of patients implanted for high-degree AVCD after TAVI had conduction recovery. Patients with cDDD programming at hospital discharge had more pacemaker dependency and a worse cardiac prognosis. Thus, pacemaker mode should be systematically set to promote spontaneous atrioventricular conduction in patients with pacemaker implantation after TAVI. © 2018 Wiley Periodicals, Inc.

Preoperative computed tomography-guided percutaneous hookwire localization of metallic marker clips in the breast with a radial approach: initial experience.

PubMed

Uematsu, T; Kasami, M; Uchida, Y; Sanuki, J; Kimura, K; Tanaka, K; Takahashi, K

2007-06-01

Hookwire localization is the current standard technique for radiological marking of nonpalpable breast lesions. Stereotactic directional vacuum-assisted breast biopsy (SVAB) is of sufficient sensitivity and specificity to replace surgical biopsy. Wire localization for metallic marker clips placed after SVAB is needed. To describe a method for performing computed tomography (CT)-guided hookwire localization using a radial approach for metallic marker clips placed percutaneously after SVAB. Nineteen women scheduled for SVAB with marker-clip placement, CT-guided wire localization of marker clips, and, eventually, surgical excision were prospectively entered into the study. CT-guided wire localization was performed with a radial approach, followed by placement of a localizing marker-clip surgical excision. Feasibility and reliability of the procedure and the incidence of complications were examined. CT-guided wire localization surgical excision was successfully performed in all 19 women without any complications. The mean total procedure time was 15 min. The median distance on CT image from marker clip to hookwire was 2 mm (range 0-3 mm). CT-guided preoperative hookwire localization with a radial approach for marker clips after SVAB is technically feasible.

Pacemakers and implantable cardioverter defibrillators--general and anesthetic considerations.

PubMed

Rapsang, Amy G; Bhattacharyya, Prithwis

2014-01-01

A pacemaking system consists of an impulse generator and lead or leads to carry the electrical impulse to the patient's heart. Pacemaker and implantable cardioverter defibrillator codes were made to describe the type of pacemaker or implantable cardioverter defibrillator implanted. Indications for pacing and implantable cardioverter defibrillator implantation were given by the American College of Cardiologists. Certain pacemakers have magnet-operated reed switches incorporated; however, magnet application can have serious adverse effects; hence, devices should be considered programmable unless known otherwise. When a device patient undergoes any procedure (with or without anesthesia), special precautions have to be observed including a focused history/physical examination, interrogation of pacemaker before and after the procedure, emergency drugs/temporary pacing and defibrillation, reprogramming of pacemaker and disabling certain pacemaker functions if required, monitoring of electrolyte and metabolic disturbance and avoiding certain drugs and equipments that can interfere with pacemaker function. If unanticipated device interactions are found, consider discontinuation of the procedure until the source of interference can be eliminated or managed and all corrective measures should be taken to ensure proper pacemaker function should be done. Post procedure, the cardiac rate and rhythm should be monitored continuously and emergency drugs and equipments should be kept ready and consultation with a cardiologist or a pacemaker-implantable cardioverter defibrillator service may be necessary. Copyright © 2013 Sociedade Brasileira de Anestesiologia. Published by Elsevier Editora Ltda. All rights reserved.

Pacemaker recycling: A notion whose time has come.

PubMed

Runge, Mason W; Baman, Timir S; Davis, Sheldon; Weatherwax, Kevin; Goldman, Ed; Eagle, Kim A; Crawford, Thomas C

2017-04-26

The purpose of this paper is to summarize the need, feasibility, safety, legality, and ethical perspectives of pacemaker reutilization in low- and middle-income countries (LMICs). It will also describe, in-depth, Project My Heart Your Heart (PMHYH) as a model for pacemaker reuse in LMICs. The primary source of the discussion points in this paper is a collection of 14 publications produced by the research team at the University of Michigan and its collaborative partners. The need for pacemaker reutilization in LMICs is evident. Numerous studies show that the concept of pacemaker reutilization in LMICs is feasible. Infection and device malfunction are the main concerns in regard to pacemaker reutilization, yet many studies have shown that pacemaker reuse is not associated with increased infection risk or higher mortality compared with new device implantation. Under the right circumstances, the ethical and legal bases for pacemaker reutilization are supported. PMHYH is a proof of concept pacemaker donation initiative that has allowed funeral home and crematory directors to send explanted devices to an academic center for evaluation and re-sterilization before donation to underserved patients in LMICs. The time is now to pursue large-scale studies and trials of pacemaker reuse for the betterment of society. PMHYH is leading the way in the effort and is poised to conduct a prospective randomized, non-inferiority, multicenter study to confirm the clinical efficacy and safety of pacemaker reuse, for clinical and legal support.

Pacemaker lead fracture associated with weightlifting: a report of two cases.

PubMed

Deering, J A; Pederson, D N

1993-12-01

Two cases of pacemaker lead fracture associated with weight-lifting are presented. This is a rare association which has only recently been described in the literature. In both cases, the pacemaker lead was fractured between the clavicle and the first rib, suggesting crush injury. The chest X-ray, pacemaker telemetry with measurement of lead impedance, and pacemaker reprogramming were all helpful in management.

Wireless power transfer for a pacemaker application.

PubMed

Vulfin, Vladimir; Sayfan-Altman, Shai; Ianconescu, Reuven

2017-05-01

An artificial pacemaker is a small medical device that uses electrical impulses, delivered by electrodes contracting the heart muscles, to regulate the beating of the heart. The pacemaker is implanted under the skin, and uses for many years regular non-rechargeable batteries. However, the demand for rechargeable batteries in pacemakers increased, and the aim of this work is to design an efficient charging system for pacemakers.

Re-use of explanted DDD pacemakers as VDD- clinical utility and cost effectiveness.

PubMed

Namboodiri, K K N; Sharma, Y P; Bali, H K; Grover, A

2004-01-01

Re-use of DDD pulse generators explanted from patients died of unrelated causes is associated with an additional cost of two transvenous leads if implanted as DDD itself, and high rate of infection according to some studies. We studied the clinical and economical aspects of reutilization of explanted DDD pacemakers programmed to VDD mode. Out of 28 patients who received VDD pacemaker during the period, October 2000- September 2001 in the Department of Cardiology, PGIMER, Chandigarh, 5 poor patients were implanted with explanted DDD pulse generators programmed to VDD mode. Each implantation was planned and carried out according to a standard protocol. The age ranged from 45 to 75 (mean-61) years. The indications for pacing were complete heart block (4) and second degree AV block (1). The clinical profile, costs and complications, if any were noted and followed up at regular intervals. The results were compared with patients who received new DDD pulse generators during this period. The additional cost for the atrial lead was not required in these patients. None of these patients had any local site infection. Compared to the two-lead system, the single lead system provided more rapid implantation and minimized complications associated with placement of an atrial lead. The explanted DDD pacemaker can be safely reused as VDD mode with same efficacy in selected patient population. This is associated with lower cost and complications compared to reimplantation as DDD itself.

Connectivity of Pacemaker Neurons in the Neonatal Rat Superficial Dorsal Horn

PubMed Central

Ford, Neil C.; Arbabi, Shahriar; Baccei, Mark L.

2014-01-01

Pacemaker neurons with an intrinsic ability to generate rhythmic burst-firing have been characterized in lamina I of the neonatal spinal cord, where they are innervated by high-threshold sensory afferents. However, little is known about the output of these pacemakers, as the neuronal populations which are targeted by pacemaker axons have yet to be identified. The present study combines patch clamp recordings in the intact neonatal rat spinal cord with tract-tracing to demonstrate that lamina I pacemaker neurons contact multiple spinal motor pathways during early life. Retrograde labeling of premotor interneurons with the trans-synaptic virus PRV-152 revealed the presence of burst-firing in PRV-infected lamina I neurons, thereby confirming that pacemakers are synaptically coupled to motor networks in the spinal ventral horn. Notably, two classes of pacemakers could be distinguished in lamina I based on cell size and the pattern of their axonal projections. While small pacemaker neurons possessed ramified axons which contacted ipsilateral motor circuits, large pacemaker neurons had unbranched axons which crossed the midline and ascended rostrally in the contralateral white matter. Recordings from identified spino-parabrachial and spino-PAG neurons indicated the presence of pacemaker activity within neonatal lamina I projection neurons. Overall, these results show that lamina I pacemakers are positioned to regulate both the level of activity in developing motor circuits as well as the ascending flow of nociceptive information to the brain, thus highlighting a potential role for pacemaker activity in the maturation of pain and sensorimotor networks in the CNS. PMID:25380417

Correlating electronic transport to atomic structures in self-assembled quantum wires.

PubMed

Qin, Shengyong; Kim, Tae-Hwan; Zhang, Yanning; Ouyang, Wenjie; Weitering, Hanno H; Shih, Chih-Kang; Baddorf, Arthur P; Wu, Ruqian; Li, An-Ping

2012-02-08

Quantum wires, as a smallest electronic conductor, are expected to be a fundamental component in all quantum architectures. The electronic conductance in quantum wires, however, is often dictated by structural instabilities and electron localization at the atomic scale. Here we report on the evolutions of electronic transport as a function of temperature and interwire coupling as the quantum wires of GdSi(2) are self-assembled on Si(100) wire-by-wire. The correlation between structure, electronic properties, and electronic transport are examined by combining nanotransport measurements, scanning tunneling microscopy, and density functional theory calculations. A metal-insulator transition is revealed in isolated nanowires, while a robust metallic state is obtained in wire bundles at low temperature. The atomic defects lead to electron localizations in isolated nanowire, and interwire coupling stabilizes the structure and promotes the metallic states in wire bundles. This illustrates how the conductance nature of a one-dimensional system can be dramatically modified by the environmental change on the atomic scale. © 2012 American Chemical Society

First percutaneous Micra leadless pacemaker implantation and tricuspid valve repair with MitraClip NT for lead-associated severe tricuspid regurgitation.

PubMed

Tang, Gilbert H L; Kaple, Ryan; Cohen, Martin; Dutta, Tanya; Undemir, Cenap; Ahmad, Hasan; Poniros, Angelica; Bennett, Joanne; Feng, Cheng; Lansman, Steven

2017-02-03

Pacemaker lead-associated severe tricuspid regurgitation (TR) can lead to right heart failure and poor prognosis. Surgery in these patients carries significant morbidities. We describe a successful treatment of symptomatic severe TR by leadless pacemaker implantation followed by tricuspid valve (TV) repair with the MitraClip NT. A 71-year-old frail female with poor functional status, chronic atrial fibrillation and permanent pacemaker implantation in 2012 presented with symptomatic moderate-severe mitral regurgitation (MR) and severe TR with the pacemaker lead as the culprit. She was deemed extreme risk for double valve surgery and, because of her pacemaker dependency, the decision was to stage her interventions first with transcatheter mitral repair, then laser lead extraction and leadless pacemaker implantation to free the TV from tethering, then TV repair. An obstructive LAD lesion was identified and treated during mitral repair with the MitraClip NT. The Micra leadless pacemaker implantation and subsequent TV repair with the MitraClip NT were successful and the patient's MR improved to mild and TR to moderate, respectively. We report here a first successful transcatheter strategy to treat lead-associated severe TR by leadless pacemaker and MitraClip. Removing the pacemaker lead relieved leaflet tethering and improved the reparability of the TV.

Pacemaker lead perforation of the right ventricle associated with Moraxella phenylpyruvica infection in a dog.

PubMed

Ciavarella, A; Nimmo, J; Hambrook, L

2016-04-01

A 13-year-old neutered male Border Collie was presented with acute onset syncope, weakness and anorexia 10 months after transvenous pacemaker implantation. The patient was laterally recumbent, bradycardic (36 beats/min) and febrile (40.7°C) on presentation. An electrocardiogram (ECG) revealed recurrence of third-degree atrioventricular block with a ventricular escape rhythm. Fluoroscopy identified migration of the pacemaker tip through the apex of the right ventricle. Echocardiography failed to reveal any evidence of pericardial effusion or cardiac tamponade. Full postmortem was performed after euthanasia. The pacemaker lead had perforated the apex of the right ventricle and lodged in the right pleural space. Culture of blood (taken antemortem), pericardial sac, right ventricular wall (surrounding pacemaker lead), pacemaker lead tip and pericardial fluid revealed a pure growth of Moraxella phenylpyruvica. Bacteraemia associated with M. phenylpyruvica has never been reported in the dog, but sporadic cases are reported in humans. Infection could have resulted from either pre-existing myocarditis or opportunistic infection and bacteraemia post pacemaker implantation. Evaluation of the pacemaker function at regular intervals would allow early detection of poor pacemaker-to-myocardium contact, which would prompt further investigation of pacemaker lead abnormalities such as perforation. © 2016 Australian Veterinary Association.

Pacemaker recycling: A notion whose time has come

PubMed Central

Runge, Mason W; Baman, Timir S; Davis, Sheldon; Weatherwax, Kevin; Goldman, Ed; Eagle, Kim A; Crawford, Thomas C

2017-01-01

The purpose of this paper is to summarize the need, feasibility, safety, legality, and ethical perspectives of pacemaker reutilization in low- and middle-income countries (LMICs). It will also describe, in-depth, Project My Heart Your Heart (PMHYH) as a model for pacemaker reuse in LMICs. The primary source of the discussion points in this paper is a collection of 14 publications produced by the research team at the University of Michigan and its collaborative partners. The need for pacemaker reutilization in LMICs is evident. Numerous studies show that the concept of pacemaker reutilization in LMICs is feasible. Infection and device malfunction are the main concerns in regard to pacemaker reutilization, yet many studies have shown that pacemaker reuse is not associated with increased infection risk or higher mortality compared with new device implantation. Under the right circumstances, the ethical and legal bases for pacemaker reutilization are supported. PMHYH is a proof of concept pacemaker donation initiative that has allowed funeral home and crematory directors to send explanted devices to an academic center for evaluation and re-sterilization before donation to underserved patients in LMICs. The time is now to pursue large-scale studies and trials of pacemaker reuse for the betterment of society. PMHYH is leading the way in the effort and is poised to conduct a prospective randomized, non-inferiority, multicenter study to confirm the clinical efficacy and safety of pacemaker reuse, for clinical and legal support. PMID:28515847

Pacemaker explosions in crematoria: problems and possible solutions

PubMed Central

Gale, Christopher P; Mulley, Graham P

2002-01-01

The number of artificial cardiac pacemakers is increasing, as is the number of bodies being cremated. Because of the explosive potential of pacemakers when heated, a statutory question on the cremation form asks whether the deceased has a pacemaker and if so whether it has been removed. We sent a questionnaire to all the crematoria in the UK enquiring about the frequency, consequences and prevention of pacemaker explosions. We found that about half of all crematoria in the UK experience pacemaker explosions, that pacemaker explosions may cause structural damage and injury and that most crematoria staff are unaware of the explosive potential of implantable cardiac defibrillators. Crematoria staff rely on the accurate completion of cremation forms, and doctors who sign cremation forms have a legal obligation to provide such information. PMID:12091510

Temporary epicardial cardiac resynchronisation versus conventional right ventricular pacing after cardiac surgery: study protocol for a randomised control trial.

PubMed

Russell, Stuart J; Tan, Christine; O'Keefe, Peter; Ashraf, Saeed; Zaidi, Afzal; Fraser, Alan G; Yousef, Zaheer R

2012-02-20

Heart failure patients with stable angina, acute coronary syndromes and valvular heart disease may benefit from revascularisation and/or valve surgery. However, the mortality rate is increased- 5-30%. Biventricular pacing using temporary epicardial wires after surgery is a potential mechanism to improve cardiac function and clinical endpoints. A multi-centred, prospective, randomised, single-blinded, intervention-control trial of temporary biventricular pacing versus standard pacing. Patients with ischaemic cardiomyopathy, valvular heart disease or both, an ejection fraction ≤ 35% and a conventional indication for cardiac surgery will be recruited from 2 cardiac centres. Baseline investigations will include: an electrocardiogram to confirm sinus rhythm and measure QRS duration; echocardiogram to evaluate left ventricular function and markers of mechanical dyssynchrony; dobutamine echocardiogram for viability and blood tests for renal function and biomarkers of myocardial injury- troponin T and brain naturetic peptide. Blood tests will be repeated at 18, 48 and 72 hours. The principal exclusions will be subjects with permanent atrial arrhythmias, permanent pacemakers, infective endocarditis or end-stage renal disease.After surgery, temporary pacing wires will be attached to the postero-lateral wall of the left ventricle, the right atrium and right ventricle and connected to a triple chamber temporary pacemaker. Subjects will be randomised to receive either temporary biventricular pacing or standard pacing (atrial inhibited pacing or atrial-synchronous right ventricular pacing) for 48 hours.The primary endpoint will be the duration of level 3 care. In brief, this is the requirement for invasive ventilation, multi-organ support or more than one inotrope/vasoconstrictor. Haemodynamic studies will be performed at baseline, 6, 18 and 24 hours after surgery using a pulmonary arterial catheter. Measurements will be taken in the following pacing modes: atrial inhibited; right ventricular only; atrial synchronous-right ventricular; atrial synchronous-left ventricular and biventricular pacing. Optimisation of the atrioventricular and interventricular delay will be performed in the biventricular pacing group at 18 hours. The effect of biventricular pacing on myocardial injury, post operative arrhythmias and renal function will also be quantified. ClinicalTrials.gov: NCT01027299.

Complications of pacemaker therapy in adults with congenital heart disease: a multicenter study.

PubMed

Opić, Petra; van Kranenburg, Matthijs; Yap, Sing-Chien; van Dijk, Arie P; Budts, Werner; Vliegen, Hubert W; van Erven, Lieselot; Can, Anil; Sahin, Gulhan; Theuns, Dominic A M J; Witsenburg, Maarten; Roos-Hesselink, Jolien W

2013-10-09

This study aims to investigate indications and complications of permanent cardiac pacing in adults with congenital heart disease (CHD). Two-hundred and seventy-four CHD patients were identified who underwent permanent pacemaker implantation between 1972 and 2009. The indication for pacing was acquired sinus node or AV node conduction disease (63%), sinus node or AV node conduction disease after cardiac surgery (28%), and drug/arrhythmia-related indications (9%). Patients with complex CHD received a pacemaker at younger age (23 versus 31 years, p<0.0001) and more often received an epicardial pacing system (51% versus 23%, p<0.0001) compared to those with simple or moderate CHD. Twenty-nine patients (10.6%) had a periprocedural complication during the primary pacemaker implantation (general population: 5.2%). The most common acute complications were lead dysfunction (4.0%), bleeding (2.6%), pocket infection (1.5%) and pneumothorax (1.5%). During a median follow-up of 12 years, pacemaker-related complications requiring intervention occurred in 95 patients (34.6%). The most common late pacemaker-related complications included lead failure (24.8%), pacemaker dysfunction/early battery depletion (5.1%), pacemaker migration (4.7%) and erosion (4.7%). Pacemaker implantation at younger age (<18 years) was an independent predictor of late pacemaker-related complication (adjusted hazard ratio 1.68, 95% confidence interval 1.07 to 2.63, p=0.023). The risk of periprocedural complications seems higher in the CHD population compared to the general population and more than one-third of CHD patients encountered a pacemaker-related complication during long-term follow-up. This risk increases for those who receive a pacemaker at younger age. Crown Copyright © 2013. Published by Elsevier Ireland Ltd. All rights reserved.

21 CFR 870.3700 - Pacemaker programmers.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Pacemaker programmers. 870.3700 Section 870.3700...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3700 Pacemaker programmers. (a) Identification. A pacemaker programmer is a device used to change noninvasively one or more of...

21 CFR 870.3720 - Pacemaker electrode function tester.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Pacemaker electrode function tester. 870.3720... (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3720 Pacemaker electrode function tester. (a) Identification. A pacemaker electrode function tester is a device which is...

21 CFR 870.3730 - Pacemaker service tools.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Pacemaker service tools. 870.3730 Section 870.3730...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3730 Pacemaker service tools. (a) Identification. Pacemaker service tools are devices such as screwdrivers and Allen wrenches...

21 CFR 870.5550 - External transcutaneous cardiac pacemaker (noninvasive).

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false External transcutaneous cardiac pacemaker... § 870.5550 External transcutaneous cardiac pacemaker (noninvasive). (a) Identification. An external transcutaneous cardiac pacemaker (noninvasive) is a device used to supply a periodic electrical pulse intended to...

21 CFR 870.5550 - External transcutaneous cardiac pacemaker (noninvasive).

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false External transcutaneous cardiac pacemaker... § 870.5550 External transcutaneous cardiac pacemaker (noninvasive). (a) Identification. An external transcutaneous cardiac pacemaker (noninvasive) is a device used to supply a periodic electrical pulse intended to...

21 CFR 870.3720 - Pacemaker electrode function tester.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Pacemaker electrode function tester. 870.3720... (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3720 Pacemaker electrode function tester. (a) Identification. A pacemaker electrode function tester is a device which is...

21 CFR 870.3630 - Pacemaker generator function analyzer.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Pacemaker generator function analyzer. 870.3630... (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3630 Pacemaker generator function analyzer. (a) Identification. A pacemaker generator function analyzer is a device that is...

21 CFR 870.3730 - Pacemaker service tools.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Pacemaker service tools. 870.3730 Section 870.3730...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3730 Pacemaker service tools. (a) Identification. Pacemaker service tools are devices such as screwdrivers and Allen wrenches...

21 CFR 870.3730 - Pacemaker service tools.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Pacemaker service tools. 870.3730 Section 870.3730...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3730 Pacemaker service tools. (a) Identification. Pacemaker service tools are devices such as screwdrivers and Allen wrenches...

21 CFR 870.3720 - Pacemaker electrode function tester.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Pacemaker electrode function tester. 870.3720... (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3720 Pacemaker electrode function tester. (a) Identification. A pacemaker electrode function tester is a device which is...

21 CFR 870.3700 - Pacemaker programmers.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Pacemaker programmers. 870.3700 Section 870.3700...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3700 Pacemaker programmers. (a) Identification. A pacemaker programmer is a device used to change noninvasively one or more of...

21 CFR 870.3730 - Pacemaker service tools.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Pacemaker service tools. 870.3730 Section 870.3730...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3730 Pacemaker service tools. (a) Identification. Pacemaker service tools are devices such as screwdrivers and Allen wrenches...

21 CFR 870.5550 - External transcutaneous cardiac pacemaker (noninvasive).

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false External transcutaneous cardiac pacemaker... § 870.5550 External transcutaneous cardiac pacemaker (noninvasive). (a) Identification. An external transcutaneous cardiac pacemaker (noninvasive) is a device used to supply a periodic electrical pulse intended to...

21 CFR 870.3720 - Pacemaker electrode function tester.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Pacemaker electrode function tester. 870.3720... (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3720 Pacemaker electrode function tester. (a) Identification. A pacemaker electrode function tester is a device which is...

21 CFR 870.3700 - Pacemaker programmers.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Pacemaker programmers. 870.3700 Section 870.3700...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3700 Pacemaker programmers. (a) Identification. A pacemaker programmer is a device used to noninvasively change one or more of...

21 CFR 870.3630 - Pacemaker generator function analyzer.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Pacemaker generator function analyzer. 870.3630... (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3630 Pacemaker generator function analyzer. (a) Identification. A pacemaker generator function analyzer is a device that is...

21 CFR 870.3630 - Pacemaker generator function analyzer.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Pacemaker generator function analyzer. 870.3630... (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3630 Pacemaker generator function analyzer. (a) Identification. A pacemaker generator function analyzer is a device that is...

21 CFR 870.3730 - Pacemaker service tools.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Pacemaker service tools. 870.3730 Section 870.3730...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3730 Pacemaker service tools. (a) Identification. Pacemaker service tools are devices such as screwdrivers and Allen wrenches...

21 CFR 870.3630 - Pacemaker generator function analyzer.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Pacemaker generator function analyzer. 870.3630... (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3630 Pacemaker generator function analyzer. (a) Identification. A pacemaker generator function analyzer is a device that is...

21 CFR 870.5550 - External transcutaneous cardiac pacemaker (noninvasive).

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false External transcutaneous cardiac pacemaker... § 870.5550 External transcutaneous cardiac pacemaker (noninvasive). (a) Identification. An external transcutaneous cardiac pacemaker (noninvasive) is a device used to supply a periodic electrical pulse intended to...

21 CFR 870.3700 - Pacemaker programmers.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Pacemaker programmers. 870.3700 Section 870.3700...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3700 Pacemaker programmers. (a) Identification. A pacemaker programmer is a device used to noninvasively change one or more of...

21 CFR 870.5550 - External transcutaneous cardiac pacemaker (noninvasive).

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false External transcutaneous cardiac pacemaker... § 870.5550 External transcutaneous cardiac pacemaker (noninvasive). (a) Identification. An external transcutaneous cardiac pacemaker (noninvasive) is a device used to supply a periodic electrical pulse intended to...

Evaluation of the effects of electric fields on implanted cardiac pacemakers. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moss, A.J.; Carstensen, E.

1985-02-01

The effects of extra high voltage (EHV) transmission line electric fields on pacemaker function were evaluated in 11 patients with seven different implanted pacemaker models from four manufacturers. Alteration in pacemaker function was demonstrated in five unipolar units (three different models) from two manufacturers during exposure to electric fields ranging from 2 to 9 kV/m, with total body currents from 47 to 175 ..mu..A. These electric fields and body currents are representative of values that can be encountered by individuals standing beneath EHV transmission lines. Transient alterations in pacemaker function observed in this study included inappropriate triggered activity, inhibition ofmore » impulse generation, reduction in rate, and reversion from demand to asynchronous mode. Electromagnetic interference from high voltage transmission lines can induce alterations in pacemaker function in certain designs of these devices. However, pacemaker manufacturers can incorporate appropriate circuits in the pacemaker design to eliminate this problem. 8 references.« less

Electromagnetic interference with pacemakers caused by portable media players.

PubMed

Thaker, Jay P; Patel, Mehul B; Jongnarangsin, Krit; Liepa, Valdis V; Thakur, Ranjan K

2008-04-01

Electromagnetic fields generated by electrical devices may cause interference with permanent pacemakers. Media players are becoming a common mode of portable entertainment. The most common media players used worldwide are iPods. These devices are often carried in a shirt chest pocket, which may place the devices close to an implanted pacemaker. The purpose of this study was to determine if iPods cause interference with pacemakers. In this prospective, single-blinded study, 100 patients who had cardiac pacemakers were tested with four types of iPods to assess for interference. Patients were monitored by a single-channel ECG monitor as well as the respective pacemaker programmer via the telemetry wand. iPods were tested by placing them 2 inches anterior to the pacemaker and wand for up to 10 seconds. To simulate actual use, standard-issue headphones were plugged into the iPods. To maintain consistency, the volume was turned up maximally, and the equalizer was turned off. A subset of 25 patients underwent testing on 2 separate days to assess for reproducibility of interference. Pacemaker interference was categorized as type I or type II telemetry interference. Type I interference was associated with atrial and/or ventricular high rates on rate histograms. Type II interference did not affect pacemaker rate counters. Electromagnetic emissions from the four iPods also were evaluated in a Faraday cage to determine the mechanism of the observed interference. One hundred patients (63 men and 37 women; mean age 77.1 +/- 7.6 years) with 11 single-chamber pacemakers and 89 dual-chamber pacemakers underwent 800 tests. The incidence of any type of interference was 51% of patients and 20% of tests. Type I interference was seen in 19% of patients and type II in 32% of patients. Reproducibility testing confirmed that interference occurred regardless of pacing configuration (unipolar or bipolar), pacing mode (AAI, VVI, or DDD), and from one day to the next. Electromagnetic emissions testing from the iPods demonstrated maximum emissions in the pacemaker carrier frequency range when the iPod was turned "on" with the headphones attached. iPods placed within 2 inches of implanted pacemakers monitored via the telemetry wand can cause interference with pacemakers.

Noise-induced effects on multicellular biopacemaker spontaneous activity: Differences between weak and strong pacemaker cells

NASA Astrophysics Data System (ADS)

Aghighi, Alireza; Comtois, Philippe

2017-09-01

Self-organization of spontaneous activity of a network of active elements is important to the general theory of reaction-diffusion systems as well as for pacemaking activity to initiate beating of the heart. Monolayer cultures of neonatal rat ventricular myocytes, consisting of resting and pacemaker cells, exhibit spontaneous activation of their electrical activity. Similarly, one proposed approach to the development of biopacemakers as an alternative to electronic pacemakers for cardiac therapy is based on heterogeneous cardiac cells with resting and spontaneously beating phenotypes. However, the combined effect of pacemaker characteristics, density, and spatial distribution of the pacemaker cells on spontaneous activity is unknown. Using a simple stochastic pattern formation algorithm, we previously showed a clear nonlinear dependency of spontaneous activity (occurrence and amplitude of spontaneous period) on the spatial patterns of pacemaker cells. In this study, we show that this behavior is dependent on the pacemaker cell characteristics, with weaker pacemaker cells requiring higher density and larger clusters to sustain multicellular activity. These multicellular structures also demonstrated an increased sensitivity to voltage noise that favored spontaneous activity at lower density while increasing temporal variation in the period of activity. This information will help researchers overcome the current limitations of biopacemakers.

21 CFR 870.1750 - External programmable pacemaker pulse generator.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false External programmable pacemaker pulse generator. 870.1750 Section 870.1750 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... External programmable pacemaker pulse generator. (a) Identification. An external programmable pacemaker...

21 CFR 870.1750 - External programmable pacemaker pulse generator.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false External programmable pacemaker pulse generator. 870.1750 Section 870.1750 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... External programmable pacemaker pulse generator. (a) Identification. An external programmable pacemaker...

21 CFR 870.1750 - External programmable pacemaker pulse generator.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false External programmable pacemaker pulse generator. 870.1750 Section 870.1750 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... External programmable pacemaker pulse generator. (a) Identification. An external programmable pacemaker...

21 CFR 870.1750 - External programmable pacemaker pulse generator.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false External programmable pacemaker pulse generator. 870.1750 Section 870.1750 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... External programmable pacemaker pulse generator. (a) Identification. An external programmable pacemaker...

21 CFR 870.1750 - External programmable pacemaker pulse generator.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false External programmable pacemaker pulse generator. 870.1750 Section 870.1750 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... External programmable pacemaker pulse generator. (a) Identification. An external programmable pacemaker...

21 CFR 870.3710 - Pacemaker repair or replacement material.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Pacemaker repair or replacement material. 870.3710... (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3710 Pacemaker repair or replacement material. (a) Identification. A pacemaker repair or replacement material is an...

21 CFR 870.3670 - Pacemaker charger.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Pacemaker charger. 870.3670 Section 870.3670 Food... DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3670 Pacemaker charger. (a) Identification. A pacemaker charger is a device used transcutaneously to recharge the batteries of a rechargeable...

21 CFR 870.3670 - Pacemaker charger.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Pacemaker charger. 870.3670 Section 870.3670 Food... DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3670 Pacemaker charger. (a) Identification. A pacemaker charger is a device used transcutaneously to recharge the batteries of a rechargeable...

21 CFR 870.3710 - Pacemaker repair or replacement material.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Pacemaker repair or replacement material. 870.3710... (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3710 Pacemaker repair or replacement material. (a) Identification. A pacemaker repair or replacement material is an...

21 CFR 870.3670 - Pacemaker charger.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Pacemaker charger. 870.3670 Section 870.3670 Food... DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3670 Pacemaker charger. (a) Identification. A pacemaker charger is a device used transcutaneously to recharge the batteries of a rechargeable...

21 CFR 870.3710 - Pacemaker repair or replacement material.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Pacemaker repair or replacement material. 870.3710... (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3710 Pacemaker repair or replacement material. (a) Identification. A pacemaker repair or replacement material is an...

21 CFR 870.3670 - Pacemaker charger.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Pacemaker charger. 870.3670 Section 870.3670 Food... DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3670 Pacemaker charger. (a) Identification. A pacemaker charger is a device used transcutaneously to recharge the batteries of a rechargeable...

21 CFR 870.3710 - Pacemaker repair or replacement material.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Pacemaker repair or replacement material. 870.3710... (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3710 Pacemaker repair or replacement material. (a) Identification. A pacemaker repair or replacement material is an...

Influence of Slippery Pacemaker Leads on Lead-Induced Venous Occlusion

NASA Astrophysics Data System (ADS)

Yang, Weiguang; Bhatia, Sagar; Obenauf, Dayna; Resse, Max; Esmaily-Moghadam, Mahdi; Feinstein, Jeffrey; Pak, On Shun

2016-11-01

The use of medical devices such as pacemakers and implantable cardiac defibrillators have become commonplace to treat arrhythmias. Pacing leads with electrodes are used to send electrical pulses to the heart to treat either abnormally slow heart rates, or abnormal rhythms. Lead induced vessel occlusion, which is commonly seen after placement of pacemaker or ICD leads, may result in lead malfunction and/or SVC syndrome, and makes lead extraction difficult. The association between the anatomic locations at risk for thrombosis and regions of venous stasis have been reported previously. The computational studies reveal obvious flow stasis in the proximity of the leads, due to the no-slip boundary condition imposed on the lead surface. With the advent of recent technologies capable of creating slippery surfaces that can repel complex fluids including blood, we explore computationally how local flow structures may be altered in the regions around the leads when the no-slip boundary condition on the lead surface is relaxed using various slip lengths. The findings evaluate the possibility of mitigating risks of lead-induced thrombosis and occlusion by implementing novel surface conditions (i.e. theoretical coatings) on the leads.

Effect of electric and magnetic fields near an HVDC converter terminal on implanted cardiac pacemakers. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frazier, M.J.

1980-08-01

The electromagnetic fields associated with HVDC converters and transmission lines constitute a unique environment for persons with implanted cardiac pacemakers. A measurement program has been conducted to assess the potential interfering effects of these harmonically rich fields on implanted pacemakers. The experimental procedures that were employed take into account the combined effects of the electric and magnetic fields. The effect of the resulting body current on the response of six pacemakers was assessed in the laboratory, using a previously developed model to relate body current to pacemaker pickup voltage. The results show that R-wave pacemaker reversion can be expected atmore » some locations within the converter facility, but that a large safety margin for unperturbed pacemaker operation exists beneath the transmission lines.« less

21 CFR 870.3650 - Pacemaker polymeric mesh bag.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Pacemaker polymeric mesh bag. 870.3650 Section 870...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3650 Pacemaker polymeric mesh bag. (a) Identification. A pacemaker polymeric mesh bag is an implanted device used to hold a...

21 CFR 870.3650 - Pacemaker polymeric mesh bag.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Pacemaker polymeric mesh bag. 870.3650 Section 870...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3650 Pacemaker polymeric mesh bag. (a) Identification. A pacemaker polymeric mesh bag is an implanted device used to hold a...

21 CFR 870.3690 - Pacemaker test magnet.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Pacemaker test magnet. 870.3690 Section 870.3690...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3690 Pacemaker test magnet. (a) Identification. A pacemaker test magnet is a device used to test an inhibited or triggered type...

21 CFR 870.3690 - Pacemaker test magnet.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Pacemaker test magnet. 870.3690 Section 870.3690...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3690 Pacemaker test magnet. (a) Identification. A pacemaker test magnet is a device used to test an inhibited or triggered type...

21 CFR 870.3690 - Pacemaker test magnet.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Pacemaker test magnet. 870.3690 Section 870.3690...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3690 Pacemaker test magnet. (a) Identification. A pacemaker test magnet is a device used to test an inhibited or triggered type...

21 CFR 870.3610 - Implantable pacemaker pulse generator.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Implantable pacemaker pulse generator. 870.3610 Section 870.3610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... pacemaker pulse generator. (a) Identification. An implantable pacemaker pulse generator is a device that has...

21 CFR 870.3650 - Pacemaker polymeric mesh bag.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Pacemaker polymeric mesh bag. 870.3650 Section 870...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3650 Pacemaker polymeric mesh bag. (a) Identification. A pacemaker polymeric mesh bag is an implanted device used to hold a...

21 CFR 870.3690 - Pacemaker test magnet.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Pacemaker test magnet. 870.3690 Section 870.3690...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3690 Pacemaker test magnet. (a) Identification. A pacemaker test magnet is a device used to test an inhibited or triggered type...

21 CFR 870.3650 - Pacemaker polymeric mesh bag.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Pacemaker polymeric mesh bag. 870.3650 Section 870...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3650 Pacemaker polymeric mesh bag. (a) Identification. A pacemaker polymeric mesh bag is an implanted device used to hold a...

Radiation effect on implanted pacemakers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pourhamidi, A.H.

1983-10-01

It was previously thought that diagnostic or therapeutic ionizing radiation did not have an adverse effect on the function of cardiac pacemakers. Recently, however, some authors have reported damaging effect of therapeutic radiation on cardiac pulse generators. An analysis of a recently-extracted pacemaker documented the effect of radiation on the pacemaker pulse generator.

Programmable Pacemaker

NASA Technical Reports Server (NTRS)

1980-01-01

St. Jude Medical's Cardiac Rhythm Management Division, formerly known as Pacesetter Systems, Inc., incorporated Apollo technology into the development of the programmable pacemaker system. This consists of the implantable pacemaker together with a physician's console containing the programmer and a data printer. Physician can communicate with patient's pacemaker by means of wireless telemetry signals transmitted through the communicating head held over the patient's chest. Where earlier pacemakers deliver a fixed type of stimulus once implanted, Programalith enables surgery free "fine tuning" of device to best suit the patient's changing needs.

Superconductor-insulator transition in long MoGe nanowires.

PubMed

Kim, Hyunjeong; Jamali, Shirin; Rogachev, A

2012-07-13

The properties of one-dimensional superconducting wires depend on physical processes with different characteristic lengths. To identify the process dominant in the critical regime we have studied the transport properties of very narrow (9-20 nm) MoGe wires fabricated by advanced electron-beam lithography in a wide range of lengths, 1-25  μm. We observed that the wires undergo a superconductor-insulator transition (SIT) that is controlled by cross sectional area of a wire and possibly also by the width-to-thickness ratio. The mean-field critical temperature decreases exponentially with the inverse of the wire cross section. We observed that a qualitatively similar superconductor-insulator transition can be induced by an external magnetic field. Our results are not consistent with any currently known theory of the SIT. Some long superconducting MoGe nanowires can be identified as localized superconductors; namely, in these wires the one-electron localization length is much smaller than the length of a wire.

Redo surgery after permanent pacemaker implantation: performance indicator of surgical techniques and pacing technology.

PubMed

Bharat, Vijaya

2004-01-01

The incidence of permanent pacemaker-related complications is reducing due to advancement of technology and increasing operator experience. There are only few series from India reporting the annual complication rates from a single center over the years. This is a series of 782 pacemakers implanted over 20 years in a secondary healthcare set-up. Eighty-two patients underwent redo surgery, either for a procedure-related complication (n=34) or for replacement of a malfunctioning/end-of-life pacemaker (n=48). Through critical analysis and corrective measures, all the procedural complications were reduced to less than 4% of the annual implantations. The introduction of a pacemaker follow-up clinic contributed to reducing the rate of elective replacement for battery depletion from 19.17% of the implanted VVI pacemakers to 0.63%. Despite being a low-volume center, with less than 100 pacemakers implanted annually, the performance of our pacing practice has shown continuous improvement.

Metallic Glass Wire Based Localization of Kinesin/Microtubule Bio-molecular Motility System

NASA Astrophysics Data System (ADS)

Kim, K.; Sikora, A.; Yaginuma, S.; Nakayama, K. S.; Nakazawa, H.; Umetsu, M.; Hwang, W.; Teizer, W.

2014-03-01

We report electrophoretic accumulation of microtubules along metallic glass (Pd42.5Cu30Ni7.5P20) wires free-standing in solution. Microtubules are dynamic cytoskeletal filaments. Kinesin is a cytoskeletal motor protein. Functions of these bio-molecules are central to various dynamic cellular processes. Functional artificial organization of bio-molecules is a prerequisite for transferring their native functions into device applications. Fluorescence microscopy at the individual-microtubule level reveals microtubules aligning along the wire axis during the electrophoretic migration. Casein-treated electrodes are effective for releasing trapped microtubules upon removal of the external field. Furthermore, we demonstrate gliding motion of microtubules on kinesin-treated metallic glass wires. The reversible manner in the local adsorption of microtubules, the flexibility of wire electrodes, and the compatibility between the wire electrode and the bio-molecules are beneficial for spatio-temporal manipulation of the motility machinery in 3 dimensions.

Wenckebach upper rate response in single chamber pacemaker.

PubMed

Barold, S S

2000-07-01

The Medtronic Minix pacemaker during normal function in the VVT mode was found to exhibit a Wenckenbach upper rate response similar to that of dual chamber devices. This behavior occurred only when the upper rate interval was longer than the pacemaker refractory period. In a single chamber device this response may simulate pacemaker malfunction.

Proton Beam Therapy Interference With Implanted Cardiac Pacemakers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oshiro, Yoshiko; Sugahara, Shinji; Noma, Mio

2008-11-01

Purpose: To investigate the effect of proton beam therapy (PBT) on implanted cardiac pacemaker function. Methods and Materials: After a phantom study confirmed the safety of PBT in patients with cardiac pacemakers, we treated 8 patients with implanted pacemakers using PBT to a total tumor dose of 33-77 gray equivalents (GyE) in dose fractions of 2.2-6.6 GyE. The combined total number of PBT sessions was 127. Although all pulse generators remained outside the treatment field, 4 patients had pacing leads in the radiation field. All patients were monitored by means of electrocardiogram during treatment, and pacemakers were routinely examined beforemore » and after PBT. Results: The phantom study showed no effect of neutron scatter on pacemaker generators. In the study, changes in heart rate occurred three times (2.4%) in 2 patients. However, these patients remained completely asymptomatic throughout the PBT course. Conclusions: PBT can result in pacemaker malfunctions that manifest as changes in pulse rate and pulse patterns. Therefore, patients with cardiac pacemakers should be monitored by means of electrocardiogram during PBT.« less

Trends in Cardiac Pacemaker Batteries

PubMed Central

Mallela, Venkateswara Sarma; Ilankumaran, V; Rao, N.Srinivasa

2004-01-01

Batteries used in Implantable cardiac pacemakers-present unique challenges to their developers and manufacturers in terms of high levels of safety and reliability. In addition, the batteries must have longevity to avoid frequent replacements. Technological advances in leads/electrodes have reduced energy requirements by two orders of magnitude. Micro-electronics advances sharply reduce internal current drain concurrently decreasing size and increasing functionality, reliability, and longevity. It is reported that about 600,000 pacemakers are implanted each year worldwide and the total number of people with various types of implanted pacemaker has already crossed 3 million. A cardiac pacemaker uses half of its battery power for cardiac stimulation and the other half for housekeeping tasks such as monitoring and data logging. The first implanted cardiac pacemaker used nickel-cadmium rechargeable battery, later on zinc-mercury battery was developed and used which lasted for over 2 years. Lithium iodine battery invented and used by Wilson Greatbatch and his team in 1972 made the real impact to implantable cardiac pacemakers. This battery lasts for about 10 years and even today is the power source for many manufacturers of cardiac pacemakers. This paper briefly reviews various developments of battery technologies since the inception of cardiac pacemaker and presents the alternative to lithium iodine battery for the near future. PMID:16943934

Next-generation pacemakers: from small devices to biological pacemakers.

PubMed

Cingolani, Eugenio; Goldhaber, Joshua I; Marbán, Eduardo

2018-03-01

Electrogenesis in the heart begins in the sinoatrial node and proceeds down the conduction system to originate the heartbeat. Conduction system disorders lead to slow heart rates that are insufficient to support the circulation, necessitating implantation of electronic pacemakers. The typical electronic pacemaker consists of a subcutaneous generator and battery module attached to one or more endocardial leads. New leadless pacemakers can be implanted directly into the right ventricular apex, providing single-chamber pacing without a subcutaneous generator. Modern pacemakers are generally reliable, and their programmability provides options for different pacing modes tailored to specific clinical needs. Advances in device technology will probably include alternative energy sources and dual-chamber leadless pacing in the not-too-distant future. Although effective, current electronic devices have limitations related to lead or generator malfunction, lack of autonomic responsiveness, undesirable interactions with strong magnetic fields, and device-related infections. Biological pacemakers, generated by somatic gene transfer, cell fusion, or cell transplantation, provide an alternative to electronic devices. Somatic reprogramming strategies, which involve transfer of genes encoding transcription factors to transform working myocardium into a surrogate sinoatrial node, are furthest along in the translational pipeline. Even as electronic pacemakers become smaller and less invasive, biological pacemakers might expand the therapeutic armamentarium for conduction system disorders.

Short- and long-term need for permanent pacemaker after transcatheter implantation of the Edwards Sapien aortic valve prosthesis.

PubMed

Moreno, Raúl; Calvo, Luis; Sánchez-Recalde, Angel; Galeote, Guillermo; Jiménez-Valero, Santiago; López, Teresa; Plaza, Ignacio; González-Davia, Rosa; Ramírez, Ulises; Mesa, Jose Maria; Moreno-Gomez, Isidro; López-Sendón, José-Luis

2015-11-01

A permanent pacemaker is frequently needed after transcatheter aortic valve implantation, but the available data are mainly on the CoreValve system. To evaluate the need for new permanent pacemaker after implantation of the Edwards Sapien device, as well as related factors. We included the first 100 patients treated with the Edwards Sapien device at our institution. Of these, 12 had a permanent pacemaker before the procedure, and thus our study population was the remaining 88 patients. A permanent pacemaker was indicated in eight patients (9.1%) during hospitalization or at 30 days. After discharge, another four patients needed a pacemaker (at 42 days and three, 18, and 30 months). Two variables were associated with the need for pacemaker during hospitalization: previous dialysis (13% vs. 1%, p=0.042) and complete right bundle branch block before the procedure (25% vs. 5%, p=0.032). More than one month after the procedure, the characteristics associated with the need for pacemaker were plasma creatinine level (2.5±1.7 vs. 1.3±0.6 mg/dl, p=0.001) and previous myocardial infarction (50% vs. 10%, p=0.013). The rate of pacemaker implantation with the Edwards Sapien device was 9.1%. Right bundle branch block and dialysis were associated with this complication.

Circadian Activators Are Expressed Days before They Initiate Clock Function in Late Pacemaker Neurons from Drosophila.

PubMed

Liu, Tianxin; Mahesh, Guruswamy; Houl, Jerry H; Hardin, Paul E

2015-06-03

Circadian pacemaker neurons in the Drosophila brain control daily rhythms in locomotor activity. These pacemaker neurons can be subdivided into early or late groups depending on whether rhythms in period (per) and timeless (tim) expression are initiated at the first instar (L1) larval stage or during metamorphosis, respectively. Because CLOCK-CYCLE (CLK-CYC) heterodimers initiate circadian oscillator function by activating per and tim transcription, a Clk-GFP transgene was used to mark when late pacemaker neurons begin to develop. We were surprised to see that CLK-GFP was already expressed in four of five clusters of late pacemaker neurons during the third instar (L3) larval stage. CLK-GFP is only detected in postmitotic neurons from L3 larvae, suggesting that these four late pacemaker neuron clusters are formed before the L3 larval stage. A GFP-cyc transgene was used to show that CYC, like CLK, is also expressed exclusively in pacemaker neurons from L3 larval brains, demonstrating that CLK-CYC is not sufficient to activate per and tim in late pacemaker neurons at the L3 larval stage. These results suggest that most late pacemaker neurons develop days before novel factors activate circadian oscillator function during metamorphosis. Copyright © 2015 the authors 0270-6474/15/358662-10$15.00/0.

Third-generation mobile phones (UMTS) do not interfere with permanent implanted pacemakers.

PubMed

Ismail, Mohamed M; Badreldin, Akmal M A; Heldwein, Matthias; Hekmat, Khosro

2010-07-01

Third-generation mobile phones, UMTS (Universal Mobile Telecommunication System), were recently introduced in Europe. The safety of these devices with regard to their interference with implanted pacemakers is as yet unknown and is the point of interest in this study. The study comprised 100 patients with permanent pacemaker implantation between November 2004 and June 2005. Two UMTS cellular phones (T-Mobile, Vodafone) were tested in the standby, dialing, and operating mode with 23 single-chamber and 77 dual-chamber pacemakers. Continuous surface electrocardiograms (ECGs), intracardiac electrograms, and marker channels were recorded when calls were made by a stationary phone to cellular phone. All pacemakers were tested under a "worst-case scenario," which includes a programming of the pacemaker to unipolar sensing and pacing modes and inducing of a maximum sensitivity setting during continuous pacing of the patient. Patients had pacemaker implantation between June 1990 and April 2005. The mean age was 68.4 +/- 15.1 years. Regardless of atrial and ventricular sensitivity settings, both UMTS mobile phones (Nokia 6650 and Motorola A835) did not show any interference with all tested pacemakers. In addition, both cellular phones did not interfere with the marker channels and the intracardiac ECGs of the pacemakers. Third-generation mobile phones are safe for patients with permanent pacemakers. This is due to the high-frequency band for this system (1,800-2,200 MHz) and the low power output between 0.01 W and 0.25 W.

The nuclear pacemaker: Is renewed interest warranted

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parsonnet, V.; Berstein, A.D.; Perry, G.Y.

1990-10-01

From 1973 through 1987, 155 radioisotope-powered nuclear pacemakers were implanted in 132 patients at the Newark Beth Israel Medical Center. The longevity of the first 15 devices, all of which were fixed-rate (VOO) pacemakers, was significantly better than that of 15 lithium-chemistry demand (VVI) pacemakers used as control devices (p = 0.0002). Of the entire cohort of 155 nuclear pacemakers, 136 were VVI devices and 19 were VOO units. The patients with VOO pacemakers needed reoperations more often than did those with VVI pacemakers, chiefly for mode change (p less than 0.001). Power-source failure was observed in only 1 case,more » but 47 nuclear pacemakers were removed for other reasons, including component malfunction (15 units), mode change (12 units), high pacing thresholds (8 units) and lead or connector problems (5 units). The actuarial survival at 15 years was 99% for power sources and 82% for the entire pacing systems (pulse generators plus leads). The frequency of malignancy was similar to that of the population at large and primary tumor sites were randomly distributed. Deaths most commonly were due to cardiac causes (68%). Thus, nuclear pacemakers are safe and reliable and their greater initial cost appears to be offset by their longevity and the resulting decrease in the frequency of reoperations. It is reasonable to suggest that further use be made of long-lasting nuclear power sources for modern pacemakers and other implantable rhythm-management devices.« less

E AND M CIRCADIAN PACEMAKER NEURONS USE DIFFERENT PDF RECEPTOR SIGNALOSOME COMPONENTS IN DROSOPHILA

PubMed Central

Duvall, Laura B.

2014-01-01

We used real-time imaging to detect cAMP levels in neurons of intact fly brains to study mechanisms of circadian pacemaker synchronization by the neuropeptide PDF in Drosophila. PDF receptor (PDF-R) is expressed by both M (sLNv) and E (LNd) pacemaker sub-classes and is coupled to Gsα in both cases. We previously reported that PDF-R in M pacemakers elevates cAMP levels by activating the ortholog of mammalian Adenylate Cyclase 3 (AC3), but that AC3 disruptions had no effect on E pacemaker sensitivity to PDF. Here we show that PDF-R in E pacemakers activates a different AC isoform, AC78C, an ortholog of mammalian AC8. Knockdown of AC78C by transgenic RNAi substantially reduces, but does not completely abrogate, PDF responses in these E pacemakers. The knockdown effect is intact when restricted to mature stages, suggesting a physiological and not a development role for AC78C in E pacemakers. The AC78C phenotype is rescued by over-expression of AC78C, but not by over-expression of the rutabaga AC. AC78C over-expression does not disrupt PDF responses in these E pacemakers, and neither AC78C knockdown nor its over-expression disrupted locomotor rhythms. Finally, knockdown of two AKAPs, nervy and AKAP 200 partially reduces LNd PDF responses. These findings begin to identify the components of E pacemaker PDF-R signalosomes and indicate they are distinct from PDF-R signalosomes in M pacemakers: we propose they contain AC78C and at least one other AC. PMID:23929551

E and M circadian pacemaker neurons use different PDF receptor signalosome components in drosophila.

PubMed

Duvall, Laura B; Taghert, Paul H

2013-08-01

We used real-time imaging to detect cAMP levels in neurons of intact fly brains to study the mechanisms of circadian pacemaker synchronization by the neuropeptide pigment dispersing factor (PDF) in Drosophila. PDF receptor (PDF-R) is expressed by both M (sLNv) and E (LNd) pacemaker subclasses and is coupled to G(sα) in both cases. We previously reported that PDF-R in M pacemakers elevates cAMP levels by activating the ortholog of mammalian adenylate cyclase 3 (AC3) but that AC3 disruptions had no effect on E pacemaker sensitivity to PDF. Here, we show that PDF-R in E pacemakers activates a different AC isoform, AC78C, an ortholog of mammalian AC8. Knockdown of AC78C by transgenic RNAi substantially reduces, but does not completely abrogate, PDF responses in these E pacemakers. The knockdown effect is intact when restricted to mature stages, suggesting a physiological and not a development role for AC78C in E pacemakers. The AC78C phenotype is rescued by the overexpression of AC78C but not by overexpression of the rutabaga AC. AC78C overexpression does not disrupt PDF responses in these E pacemakers, and neither AC78C knockdown nor its overexpression disrupted locomotor rhythms. Finally, knockdown of 2 AKAPs, nervy and AKAP200, partially reduces LNd PDF responses. These findings begin to identify the components of E pacemaker PDF-R signalosomes and indicate that they are distinct from PDF-R signalosomes in M pacemakers: we propose they contain AC78C and at least 1 other AC.

The pacemaker-twiddler's syndrome: an infrequent cause of pacemaker failure.

PubMed

Salahuddin, Mohammad; Cader, Fathima Aaysha; Nasrin, Sahela; Chowdhury, Mashhud Zia

2016-01-20

The pacemaker-twiddler's syndrome is an uncommon cause of pacemaker malfunction. It occurs due to unintentional or deliberate manipulation of the pacemaker pulse generator within its skin pocket by the patient. This causes coiling of the lead and its dislodgement, resulting in failure of ventricular pacing. More commonly reported among elderly females with impaired cognition, the phenomenon usually occurs in the first year following pacemaker implantation. Treatment involves repositioning of the dislodged leads and suture fixation of the lead and pulse generator within its pocket. An 87 year old Bangladeshi lady who underwent a single chamber ventricular pacemaker (VVI mode: i.e. ventricle paced, ventricle sensed, inhibitory mode) implantation with the indication of complete heart block, and presented to us again 7 weeks later, with syncopal attacks. She admitted to repeatedly manipulating the pacemaker generator in her left pectoral region. Physical examination revealed a heart rate of 42 beats/minute, blood pressure 140/80 mmHg and bilateral crackles on lung auscultation. She had no cognitive deficit. An immediate electrocardiogram showed complete heart block with pacemaker spikes and failure to capture. Chest X-ray showed coiled and retracted right ventricular lead and rotated pulse generator. An emergent temporary pace maker was set at a rate of 60 beats per minute. Subsequently, she underwent successful lead repositioning with strong counselling to avoid further twiddling. Twiddler's syndrome should be considered as a cause of pacemaker failure in elderly patients presenting with bradyarrythmias following pacemaker implantation. Chest X-ray and electrocardiograms are simple and easily-available first line investigations for its diagnosis. Lead repositioning is required, however proper patient education and counselling against further manipulation is paramount to long-term management.

[Atrial fibrillation before and after pacemaker implantation (WI and DDD) in patients with complete atrioventricular block].

PubMed

Matusik, Paweł; Woznica, Natalia; Lelakowsk, Jacek

2010-05-01

Atrial fibrillation (AF) is a frequent problem of patients with pacemakers, and depends not only on disease but also on stimulation method. The aim of the study was to estimate the prevalence of AF before and after pacemaker implantation as well as to assess the influence of VVI and DDD cardiac pacing on onset of AF in patients with complete atrioventricularblock (AVB). We included 155 patients controlled between 2000 and 2008 in Pacemaker Clinic because of AVB III degree, treated with VVI or DDD pacemaker implantation. Information about the health status of the patients was gathered from medical documentation and analysis of clinical ambulatory electrocardiograms. The study group comprised of 68 women and 87 men, mean age 68.7 +/- 13.9 years during implantation. 69% of patients had VVI pacemaker. There were 72.3% of patients with sinus rhythm before pacemaker implantation. During follow-up 4 +/- 2.8 years in 19.6% cases onset of atrial fibrillation de novo was diagnosed (in 31.3% in VVI mode vs. 2.2% in DDD mode; p = 0.00014). Mean time to AF since implantation was approximately 2.5 years. In VVI group (21 persons) amounted 32.1 months, while in 1 patient with DDD pacemaker 18 months. Between group with AF after implantation and with sinus rhythm preserved there was no statistically significant difference in age or gender (p = 0.89512 and p = 0.1253, respectively). Prevalence of atrial fibrillation after pacemaker implantation increased to 40%. Atrial fibrillation is frequent in patients before and after pacemaker implantation, especially in patients stimulated in VVI mode. Major possibility of atrial fibrillation onset after pacemaker implantation should result in more attention during routine ECG examination.

The effect of single engine fixed wing air transport on rate-responsive pacemakers.

PubMed

De Rotte, A A; Van Der Kemp, P

1999-09-01

Insufficient information exists about the safety of patients with accelerometer-based rate-responsive pacemakers in air transport by general aviation aircraft. The response in pacing rate of two types of accelerometer-based rate-responsive pacemakers with data logging capabilities was studied during test flights with single engine fixed wing aircraft. Results were compared with the rate-response of these pacemakers during transportation by car and were also interpreted in respect to physiological heart rate response of aircrew during flights in single engine fixed wing aircraft. In addition, a continuous accelerometer readout was recorded during a turbulent phase of flight. This recording was used for a pacemaker-simulator experiment with maximal sensitive motion-sensor settings. Only a minor increase in pacing rate due to aircraft motion could be demonstrated during all phases of flight at all altitudes with the pacemakers programmed in the normal mode. This increase was of the same magnitude as induced during transport by car and would be of negligible influence on the performance of the individual pacemaker patient equipped with such a pacemaker. Moreover, simultaneous Holter monitoring of the pilots during these flights showed a similar rate-response in natural heart rate compared with the increase in pacing rate induced by aircraft motion in accelerometer-based rate-responsive pacemakers. No sensor-mediated pacemaker tachycardia was seen during any of these recordings. However, a 15% increase in pacing rate was induced by severe air turbulence. Programming the maximal sensitivity of the motion sensor into the pacemaker could, on the other hand, induce a significant increase in pacing rate as was demonstrated by the simulation experiments. These results seem to rule out potentially dangerous or adverse effects from motional or vibrational influences during transport in single engine fixed wing aircraft on accelerometer-based rate-responsive pacemakers with normal activity sensor settings.

Intermittent pacemaker dysfunction caused by digital mobile telephones.

PubMed

Naegeli, B; Osswald, S; Deola, M; Burkart, F

1996-05-01

This study was designed to evaluate possible interactions between digital mobile telephones and implanted pacemakers. Electromagnetic fields may interfere with normal pacemaker function. Development of bipolar sensing leads and modern noise filtering techniques have lessened this problem. However, it remains unclear whether these features also protect from high frequency noise arising from digital cellular phones. In 39 patients with an implanted pacemaker (14 dual-chamber [DDD], 8 atrial-synchronized ventricular-inhibited [VDD(R)] and 17 ventricular-inhibited [VVI(R)] pacemakers), four mobile phones with different levels of power output (2 and 8 W) were tested in the standby, dialing and operating mode. During continuous electrocardiographic monitoring, 672 tests were performed in each mode with the phones positioned over the pulse generator, the atrial and the ventricular electrode tip. The tests were carried out at different sensitivity settings and, where possible, in the unipolar and bipolar pacing modes as well. In 7 (18%) of 39 patients, a reproducible interference was induced during 26 (3.9%) of 672 tests with the operating phones in close proximity (<10 cm) to the pacemaker. In 22 dual-chamber (14 DDD, 8 VDD) pacemakers, atrial triggering occurred in 7 (2.8%) of 248 and ventricular inhibition in 5 (2.8%) of 176 tests. In 17 VVI(R) systems, pacemaker inhibition was induced in 14 (5.6%) of 248 tests. Interference was more likely to occur at higher power output of the phone and at maximal sensitivity of the pacemakers (maximal vs. nominal sensitivity, 6% vs. 1.8% positive test results, p = 0.009). When the bipolar and unipolar pacing modes were compared in the same patients, ventricular inhibition was induced only in the unipolar mode (12.5% positive test results, p = 0.0003). Digital mobile phones in close proximity to implanted pacemakers may cause intermittent pacemaker dysfunction with inappropriate ventricular tracking and potentially dangerous pacemaker inhibition.

The interference of electronic implants in low frequency electromagnetic fields.

PubMed

Silny, J

2003-04-01

Electronic implants such as cardiac pacemakers or nerve stimulators can be impaired in different ways by amplitude-modulated and even continuous electric or magnetic fields of strong field intensities. For the implant bearer, possible consequences of a temporary electromagnetic interference may range from a harmless impairment of his well-being to a perilous predicament. Electromagnetic interferences in all types of implants cannot be covered here due to their various locations in the body and their different sensing systems. Therefore, this presentation focuses exemplarily on the most frequently used implant, the cardiac pacemaker. In case of an electromagnetic interference the cardiac pacemaker reacts by switching to inhibition mode or to fast asynchronous pacing. At a higher disturbance voltage on the input of the pacemaker, a regular asynchronous pacing is likely to arise. In particular, the first-named interference could be highly dangerous for the pacemaker patient. The interference threshold of cardiac pacemakers depends in a complex way on a number of different factors such as: electromagnetic immunity and adjustment of the pacemaker, the composition of the applied low-frequency fields (only electric or magnetic fields or combinations of both), their frequencies and modulations, the type of pacemaker system (bipolar, unipolar) and its location in the body, as well as the body size and orientation in the field, and last but not least, certain physiological conditions of the patient (e.g. inhalation, exhalation). In extensive laboratory studies we have investigated the interference mechanisms in more than 100 cardiac pacemakers (older types as well as current models) and the resulting worst-case conditions for pacemaker patients in low-frequency electric and magnetic fields. The verification of these results in different practical everyday-life situations, e.g. in the fields of high-voltage overhead lines or those of electronic article surveillance systems is currently in progress. In case of the vertically-oriented electric 50 Hz fields preliminary results show that per 1 kV/m unimpaired electrical field strength (rms) an interference voltage of about 400 microVpp as worst-case could occur at the input of a unipolar ventricularly controlled, left-pectorally implanted cardiac pacemaker. Thus, already a field strength above ca. 5 kV/m could cause an interference with an implanted pacemaker. The magnetic fields induces an electric disturbance voltage at the input of the pacemaker. The body and the pacemaker system compose several induction loops, whose induced voltages rates add or subtract. The effective area of one representing inductive loop ranges from 100 to 221 cm2. For the unfavourable left-pectorally implantated and atrially-controlled pacemaker with a low interference threshold, the interference threshold ranges between 552 and 16 microT (rms) for magnetic fields at frequencies between 10 and 250 Hz. On this basis the occurrence of interferences with implanted pacemakers is possible in everyday-life situations. But experiments demonstrate a low probability of interference of cardiac pacemakers in practical situations. This apparent contradiction can be explained by a very small band of inhibition in most pacemakers and, in comparison with the worst-case, deviating conditions.

Quantum Monte Carlo Studies of Interaction-Induced Localization in Quantum Dots and Wires

NASA Astrophysics Data System (ADS)

Devrim Güçlü, A.

2009-03-01

We investigate interaction-induced localization of electrons in both quantum dots and inhomogeneous quantum wires using variational and diffusion quantum Monte Carlo methods. Quantum dots and wires are highly tunable systems that enable the study of the physics of strongly correlated electrons. With decreasing electronic density, interactions become stronger and electrons are expected to localize at their classical positions, as in Wigner crystallization in an infinite 2D system. (1) Dots: We show that the addition energy shows a clear progression from features associated with shell structure to those caused by commensurability of a Wigner crystal. This cross-over is, then, a signature of localization; it occurs near rs˜20. For higher values of rs, the configuration symmetry of the quantum dot becomes fully consistent with the classical ground state. (2) Wires: We study an inhomogeneous quasi-one-dimensional system -- a wire with two regions, one at low density and the other high. We find that strong localization occurs in the low density quantum point contact region as the gate potential is increased. The nature of the transition from high to low density depends on the density gradient -- if it is steep, a barrier develops between the two regions, causing Coulomb blockade effects. We find no evidence for ferromagnetic spin polarization for the range of parameters studied. The picture emerging here is in good agreement with the experimental measurements of tunneling between two wires. Collaborators: C. J. Umrigar (Cornell), Hong Jiang (Fritz Haber Institut), Amit Ghosal (IISER Calcutta), and H. U. Baranger (Duke).

Spectral function of few electrons in quantum wires and carbon nanotubes as a signature of Wigner localization

NASA Astrophysics Data System (ADS)

Secchi, Andrea; Rontani, Massimo

2012-03-01

We demonstrate that the profile of the space-resolved spectral function at finite temperature provides a signature of Wigner localization for electrons in quantum wires and semiconducting carbon nanotubes. Our numerical evidence is based on the exact diagonalization of the microscopic Hamiltonian of few particles interacting in gate-defined quantum dots. The minimal temperature required to suppress residual exchange effects in the spectral function image of (nanotubes) quantum wires lies in the (sub)kelvin range.

Electromagnetic interference with cardiac pacemakers and implantable cardioverter-defibrillators from low-frequency electromagnetic fields in vivo.

PubMed

Tiikkaja, Maria; Aro, Aapo L; Alanko, Tommi; Lindholm, Harri; Sistonen, Heli; Hartikainen, Juha E K; Toivonen, Lauri; Juutilainen, Jukka; Hietanen, Maila

2013-03-01

Electromagnetic interference (EMI) can pose a danger to workers with pacemakers and implantable cardioverter-defibrillators (ICDs). At some workplaces electromagnetic fields are high enough to potentially inflict EMI. The purpose of this in vivo study was to evaluate the susceptibility of pacemakers and ICDs to external electromagnetic fields. Eleven volunteers with a pacemaker and 13 with an ICD were exposed to sine, pulse, ramp, and square waveform magnetic fields with frequencies of 2-200 Hz using Helmholtz coil. The magnetic field flux densities varied to 300 µT. We also tested the occurrence of EMI from an electronic article surveillance (EAS) gate, an induction cooktop, and a metal inert gas (MIG) welding machine. All pacemakers were tested with bipolar settings and three of them also with unipolar sensing configurations. None of the bipolar pacemakers or ICDs tested experienced interference in any of the exposure situations. The three pacemakers with unipolar settings were affected by the highest fields of the Helmholtz coil, and one of them also by the EAS gate and the welding cable. The induction cooktop did not interfere with any of the unipolarly programmed pacemakers. Magnetic fields with intensities as high as those used in this study are rare even in industrial working environments. In most cases, employees can return to work after implantation of a bipolar pacemaker or an ICD, after an appropriate risk assessment. Pacemakers programmed to unipolar configurations can cause danger to their users in environments with high electromagnetic fields, and should be avoided, if possible.

Pacemaker diagnostics in atrial fibrillation: limited usefulness for therapy initiation in a pacemaker practice.

PubMed

Yedlapati, Neeraja; Fisher, John D

2014-09-01

We aimed to determine the practical value of pacemaker diagnostics for atrial fibrillation (AF) in an unselected general pacemaker practice, specifically workflow and initiation of anticoagulation or antiarrhythmic drug (AAD) therapy. We prospectively followed consecutive pacemaker interrogations over a period of 1 year to identify patients with AF (burden from 1% to 99%). We contacted referring physicians with AF details, and then determined whether the information resulted in therapeutic changes. Of the 1,100 pacemakers interrogated, 728 were dual chamber (DDDs) with AF diagnostic capability. AF was recorded in 73 (10%) but seven had limited information, leaving 66 patients; of these, 42 (63%) patients were already anticoagulated and in five (7%) patients, anticoagulation had been stopped because of complications. Initial diagnosis of AF was made by the pacemaker in 17 patients (26% of 66; 2% of 728); four (6% of 66) patients were newly initiated on anticoagulation. Of the 66 patients, 17 patients were already on AADs; 49 (74%) had satisfactory rate control or had other issues; only two (3% of 66; 0.3% of 728) received new AADs. Of 728 patients with DDD pacemakers, only 17 were newly discovered to have AF, and six (0.8%) had changes in medications based on the pacemaker data. Adding pacemaker-derived data to existing clinical information had little therapeutic impact, due to a combination of cumbersome workflow, and because AF was usually known to practitioners. Developments in automated monitoring systems may provide more accessible and therapeutically useful information. ©2014 Wiley Periodicals, Inc.

Cardiac MRI in patients with complex CHD following primary or secondary implantation of MRI-conditional pacemaker system.

PubMed

Al-Wakeel, Nadya; O h-Ici, Darach; Schmitt, Katharina R; Messroghli, Daniel R; Riesenkampff, Eugénie; Berger, Felix; Kuehne, Titus; Peters, Bjoern

2016-02-01

In patients with CHD, cardiac MRI is often indicated for functional and anatomical assessment. With the recent introduction of MRI-conditional pacemaker systems, cardiac MRI has become accessible for patients with pacemakers. The present clinical study aims to evaluate safety, susceptibility artefacts, and image reading of cardiac MRI in patients with CHD and MRI-conditional pacemaker systems. Material and methods CHD patients with MRI-conditional pacemaker systems and a clinical need for cardiac MRI were examined with a 1.5-T MRI system. Lead function was tested before and after MRI. Artefacts and image readings were evaluated using a four-point grading scale. A total of nine patients with CHD (mean age 34.0 years, range 19.5-53.6 years) received a total of 11 cardiac MRI examinations. Owing to clinical indications, seven patients had previously been converted from conventional to MRI-conditional pacemaker systems. All MRI examinations were completed without adverse effects. Device testing immediately after MRI and at follow-up showed no alteration of pacemaker device and lead function. Clinical questions could be addressed and answered in all patients. Cardiac MRI can be performed safely with high certainty of diagnosis in CHD patients with MRI-conditional pacemaker systems. In case of clinically indicated lead and box changing, CHD patients with non-MRI-conditional pacemaker systems should be considered for complete conversion to MRI-conditional systems.

The retrospectroscope-the invention of the rechargeable cardiac pacemaker: vignette #9.

PubMed

Fischell, R E

1990-01-01

The idea for a rechargeable cardiac pacemaker came to the author in the late 1960s after reading an advertisement stating that a company's batteries were so good they would last two years in a heart pacemaker. This meant that pacemaker patients would have to undergo surgery for their replacement frequently. Having worked on the development of hermetically sealed, nickel-cadmium batteries that could function for a decade or longer in an orbiting spacecraft, the author constructed the first prototype of a rechargeable cardiac pacemaker around 1968 to show cardiologists at Johns Hopkins Hospital that a pacemaker of indefinitely long life and much smaller size and weight could be built readily. The subsequent development and marketing of the device, which came on the market in 1973, is recounted.

Permanent pacemaker lead induced severe tricuspid regurgitation in patient undergoing multiple valve surgery.

PubMed

Lee, Jung Hee; Kim, Tae Ho; Kim, Wook Sung

2015-04-01

Severe and permanent tricuspid regurgitation induced by pacemaker leads is rarely reported in the literature. The mechanism of pacemaker-induced tricuspid regurgitation has been identified, but its management has not been well established. Furthermore, debate still exists regarding the proper surgical approach. We present the case of a patient with severe tricuspid regurgitation induced by a pacemaker lead, accompanied by triple valve disease. The patient underwent double valve replacement and tricuspid valve repair without removal of the pre-existing pacemaker lead. The operation was successful and the surgical procedure is discussed in detail.

The effects of nuclear magnetic resonance on patients with cardiac pacemakers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pavlicek, W.; Geisinger, M.; Castle, L.

1983-04-01

The effect of nuclear magnetic resonance (NMR) imaging on six representative cardiac pacemakers was studied. The results indicate that the threshold for initiating the asynchronous mode of a pacemaker is 17 gauss. Radiofrequency levels are present in an NMR unit and may confuse or possibly inhibit demand pacemakers, although sensing circuitry is normally provided with electromagnetic interference discrimination. Time-varying magnetic fields can generate pulse amplitudes and frequencies to mimic cardiac activity. A serious limitation in the possibility of imaging a patient with a pacemaker would be the alteration of normal pulsing parameters due to time-varying magnetic fields.

21 CFR Appendix B to Subpart B of... - Scope of Product Coverage

Code of Federal Regulations, 2013 CFR

2013-04-01

... Portable air compressor 2 Cardiovascular Panel Cardiovascular Diagnostic 870.1425 Programmable diagnostic... Pacemaker & Accessories 870.1750 External programmable pacemaker pulse generator 2 870.3630 Pacemaker...

21 CFR Appendix B to Subpart B of... - Scope of Product Coverage

Code of Federal Regulations, 2014 CFR

2014-04-01

... Portable air compressor 2 Cardiovascular Panel Cardiovascular Diagnostic 870.1425 Programmable diagnostic... Pacemaker & Accessories 870.1750 External programmable pacemaker pulse generator 2 870.3630 Pacemaker...

21 CFR Appendix B to Subpart B of... - Scope of Product Coverage

Code of Federal Regulations, 2012 CFR

2012-04-01

... Portable air compressor 2 Cardiovascular Panel Cardiovascular Diagnostic 870.1425 Programmable diagnostic... Pacemaker & Accessories 870.1750 External programmable pacemaker pulse generator 2 870.3630 Pacemaker...

Devices for Arrhythmia

MedlinePlus

... with recurrent arrhythmias, medical devices such as a pacemaker and implantable cardioverter defibrillator (ICD) can help by ... with an ICD Questions to ask your doctor Pacemakers Learn what an artificial pacemaker is, how it ...

Heart pacemaker

MedlinePlus

... please enable JavaScript. A pacemaker is a small, battery-operated device. This device senses when your heart ... pacemakers have 2 parts: The generator contains the battery and the information to control the heartbeat. The ...

Understanding Irreversible Degradation of Nb3Sn Wires with Fundamental Fracture Mechanics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhai, Yuhu; Calzolaio, Ciro; Senatore, Carmine

2014-08-01

Irreversible performance degradation of advanced Nb3Sn superconducting wires subjected to transverse or axial mechanical loading is a critical issue for the design of large-scale fusion and accelerator magnets such as ITER and LHC. Recent SULTAN tests indicate that most cable-in-conduit conductors for ITER coils made of Nb3Sn wires processed by various fabrication techniques show similar performance degradation under cyclic loading. The irreversible degradation due to filament fracture and local strain accumulation in Nb3Sn wires cannot be described by the existing strand scaling law. Fracture mechanic modeling combined with X-ray diffraction imaging of filament micro-crack formation inside the wires under mechanicalmore » loading may reveal exciting insights to the wire degradation mechanisms. We apply fundamental fracture mechanics with a singularity approach to study influence of wire filament microstructure of initial void size and distribution to local stress concentration and potential crack propagation. We report impact of the scale and density of the void structure on stress concentration in the composite wire materials for crack initiation. These initial defects result in an irreversible degradation of the critical current beyond certain applied stress. We also discuss options to minimize stress concentration in the design of the material microstructure for enhanced wire performance for future applications.« less

MRI-guided Wire Localization Surgical Biopsy in an Adolescent Patient with a Difficult to Diagnose Case of Lymphoma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thompson, Scott M., E-mail: Thompson.scott@mayo.edu; Gorny, Krzysztof R.; Jondal, Danielle E.

A 17-year-old previously healthy female presented with a progressive soft tissue infiltrative process involving the neck and thorax. Extensive diagnostic evaluation including multiple imaging, laboratory, and biopsy studies was nondiagnostic. Due to an urgent need to establish a diagnosis and several previous nondiagnostic biopsies, she was referred to interventional radiology for MRI-guided wire localization immediately prior to open surgical biopsy. Under general anesthesia, wires were placed in the areas of increased T2 signal within the bilateral splenius capitis muscles using intermittent MRI-guidance followed by immediate surgical biopsy down to the wires. Pathology confirmed the diagnosis of diffuse large B-cell lymphoma.

Pacemaker (image)

MedlinePlus

A pacemaker is a small, battery-operated electronic device which is inserted under the skin to help the heart beat regularly and at an appropriate rate. The pacemaker has leads that travel through a large vein ...

The usefulness of a stretch-polyester pouch to encase implanted pacemakers and defibrillators.

PubMed

Parsonnet, V; Bernstein, A D; Neglia, D; Omar, A

1994-12-01

This study was undertaken to assess the effects of enclosing permanent pacemaker and ICD pulse generators in a stretch-polyester pouch prior to implantation. Follow-up of 223 patients with oversized pacemakers and with ICDs and 344 with standard-sized pacemaker pulse generators showed that the pouch was effective in decreasing the frequency of pulse generator migration and extrusion.

Deterioration of autonomic neuronal receptor signaling and mechanisms intrinsic to heart pacemaker cells contribute to age-associated alterations in heart rate variability in vivo.

PubMed

Yaniv, Yael; Ahmet, Ismayil; Tsutsui, Kenta; Behar, Joachim; Moen, Jack M; Okamoto, Yosuke; Guiriba, Toni-Rose; Liu, Jie; Bychkov, Rostislav; Lakatta, Edward G

2016-08-01

We aimed to determine how age-associated changes in mechanisms extrinsic and intrinsic to pacemaker cells relate to basal beating interval variability (BIV) reduction in vivo. Beating intervals (BIs) were measured in aged (23-25 months) and adult (3-4 months) C57BL/6 male mice (i) via ECG in vivo during light anesthesia in the basal state, or in the presence of 0.5 mg mL(-1) atropine + 1 mg mL(-1) propranolol (in vivo intrinsic conditions), and (ii) via a surface electrogram, in intact isolated pacemaker tissue. BIV was quantified in both time and frequency domains using linear and nonlinear indices. Although the average basal BI did not significantly change with age under intrinsic conditions in vivo and in the intact isolated pacemaker tissue, the average BI was prolonged in advanced age. In vivo basal BIV indices were found to be reduced with age, but this reduction diminished in the intrinsic state. However, in pacemaker tissue BIV indices increased in advanced age vs. adults. In the isolated pacemaker tissue, the sensitivity of the average BI and BIV in response to autonomic receptor stimulation or activation of mechanisms intrinsic to pacemaker cells by broad-spectrum phosphodiesterase inhibition declined in advanced age. Thus, changes in mechanisms intrinsic to pacemaker cells increase the average BIs and BIV in the mice of advanced age. Autonomic neural input to pacemaker tissue compensates for failure of molecular intrinsic mechanisms to preserve average BI. But this compensation reduces the BIV due to both the imbalance of autonomic neural input to the pacemaker cells and altered pacemaker cell responses to neural input. © 2016 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.

Risk Factors For Bradycardia Requiring Pacemaker Implantation In Patients With Atrial Fibrillation

PubMed Central

Barrett, Tyler W.; Abraham, Robert L.; Jenkins, Cathy A.; Russ, Stephan; Storrow, Alan B.; Darbar, Dawood

2012-01-01

Symptomatic bradycardia may complicate atrial fibrillation (AF) and necessitate a permanent pacemaker. Identifying patients at increased risk for symptomatic bradycardia may reduce associated morbidities and healthcare costs. We investigated predictors for developing bradycardia requiring a permanent pacemaker among AF patients. We reviewed records of all patients treated for AF/flutter in an academic hospital’s emergency department from 8/1/2005 to 8/30/2008. We determined survival and presence of a pacemaker as of 11/1/2011. Cases were defined as patients with pacemakers placed for bradycardia after their AF diagnoses. Patients without a pacemaker who were followed at our hospital comprised the controls. We identified a priori variables for the logistic regression analysis. We fit a post-hoc model adjusting for AF type and atrioventricular nodal blocker (AVN) use. Of the 362 patients in our cohort, 119 cases had permanent pacemakers implanted for bradycardia subsequent to AF diagnosis and 243 controls were alive without a pacemaker. Median and interquartile range follow-up time was 4.5 (3.8 – 5.4) years. Odds ratios and 95% confidence intervals were determined for age at time of AF diagnosis (1.02 [1, 1.04]), female (1.58 [0.95, 2.63]), prior heart failure (2.72 [1.47, 5.01]), and African-American (0.33 [0.12, 0.94]). Post-hoc model identified permanent AF (2.99 [1.61, 5.57]) and AVN use (1.43 [0.85, 2.4]). In conclusion, among AF patients, heart failure and permanent AF each nearly triple the odds of developing bradycardia requiring a permanent pacemaker; while not statistically significant, our results suggest that women are more likely and African-Americans less likely to develop bradycardia requiring pacemaker implantation. PMID:22840846

Effects of pine needle extract on pacemaker currents in interstitial cells of Cajal from the murine small intestine.

PubMed

Cheong, Hyeonsook; Paudyal, Dilli Parasad; Jun, Jae Yeoul; Yeum, Cheol Ho; Yoon, Pyung Jin; Park, Chan Guk; Kim, Man Yoo; So, Insuk; Kim, Ki Whan; Choi, Seok

2005-10-31

Extracts of pine needles (Pinus densiflora Sieb. et Zucc.) have diverse physiological and pharmacological actions. In this study we show that pine needle extract alters pacemaker currents in interstitial cells of Cajal (ICC) by modulating ATP-sensitive K+ channels and that this effect is mediated by prostaglandins. In whole cell patches at 30 degrees , ICC generated spontaneous pacemaker potentials in the current clamp mode (I = 0), and inward currents (pacemaker currents) in the voltage clamp mode at a holding potential of -70 mV. Pine needle extract hyperpolarized the membrane potential, and in voltage clamp mode decreased both the frequency and amplitude of the pacemaker currents, and increased the resting currents in the outward direction. It also inhibited the pacemaker currents in a dose-dependent manner. Because the effects of pine needle extract on pacemaker currents were the same as those of pinacidil (an ATP-sensitive K+ channel opener) we tested the effect of glibenclamide (an ATP-sensitive K+ channels blocker) on ICC exposed to pine needle extract. The effects of pine needle extract on pacemaker currents were blocked by glibenclamide. To see whether production of prostaglandins (PGs) is involved in the inhibitory effect of pine needle extract on pacemaker currents, we tested the effects of naproxen, a non-selective cyclooxygenase (COX-1 and COX-2) inhibitor, and AH6809, a prostaglandin EP1 and EP2 receptor antagonist. Naproxen and AH6809 blocked the inhibitory effects of pine needle extract on ICC. These results indicate that pine needle extract inhibits the pacemaker currents of ICC by activating ATP-sensitive K+ channels via the production of PGs.

Pacemaker Use in New Zealand - Data From the New Zealand Implanted Cardiac Device Registry (ANZACS-QI 15).

PubMed

Larsen, P D; Kerr, A J; Hood, M; Harding, S A; Hooks, D; Heaven, D; Lever, N A; Sinclair, S; Boddington, D; Tang, E W; Swampillai, J; Stiles, M K

2017-03-01

The New Zealand Cardiac Implanted Device Registry (Device) has recently been developed under the auspices of the New Zealand Branch of the Cardiac Society of Australia and New Zealand. This study describes the initial Device registry cohort of patients receiving a new pacemaker, their indications for pacing and their perioperative complications. The Device Registry was used to audit patients receiving a first pacemaker between 1 st January 2014 and 1 st June 2015. We examined 1611 patients undergoing first pacemaker implantation. Patients were predominantly male (59%), and had a median age of 70 years. The most common symptom for pacemaker implantation was syncope (39%), followed by dizziness (30%) and dyspnoea (12%). The most common aetiology for a pacemaker was a conduction tissue disorder (35%), followed by sinus node dysfunction (22%). Atrioventricular (AV) block was the most common ECG abnormality, present in 44%. Dual chamber pacemakers were most common (62%), followed by single chamber ventricular pacemakers (34%), and cardiac resynchronisation therapy - pacemakers (CRT-P) (2%). Complications within 24hours of the implant procedure were reported in 64 patients (3.9%), none of which were fatal. The most common complication was the need for reoperation to manipulate a lead, occurring in 23 patients (1.4%). This is the first description of data entered into the Device registry. Patients receiving a pacemaker were younger than in European registries, and there was a low use of CRT-P devices compared to international rates. Complications rates were low and compare favourably to available international data. Copyright © 2016 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

Laser Annealing on the Surface Treatment of Thin Super Elastic NiTi Wire

NASA Astrophysics Data System (ADS)

Samal, S.; Heller, L.; Brajer, J.; Tyc, O.; Kadrevek, L.; Sittner, P.

2018-05-01

Here the aim of this research is annealing the surface of NiTi wire for shape memory alloy, super-elastic wire by solid state laser beam. The laser surface treatment was carried out on the NiTi wire locally with fast, selective, surface heat treatment that enables precisely tune the localized material properties without any precipitation. Both as drawn (hard) and straight annealing NiTi wire were considered for laser annealing with input power 3 W, with precisely focusing the laser beam height 14.3 % of the Z-axis with a spot size of 1 mm. However, straight annealing wire is more interest due to its low temperature shape setting behavior and used by companies for stent materials. The variable parameter such as speed of the laser scanning and tensile stress on the NiTi wire were optimized to observe the effect of laser response on the sample. Superelastic, straight annealed NiTi wires (d: 0.10 mm) were held prestrained at the end of the superelastic plateau (ε: 5 ∼6.5 %) above the superelastic region by a tensile machine ( Mitter: miniature testing rig) at room temperature (RT). Simultaneously, the hardness of the wires along the cross-section was performed by nano-indentation (NI) method. The hardness of the NiTi wire corresponds to phase changes were correlated with NI test. The laser induced NiTi wire shows better fatigue performance with improved 6500 cycles.

Zebrafish heart as a model to study the integrative autonomic control of pacemaker function

PubMed Central

Stoyek, Matthew R.; Quinn, T. Alexander; Croll, Roger P.

2016-01-01

The cardiac pacemaker sets the heart's primary rate, with pacemaker discharge controlled by the autonomic nervous system through intracardiac ganglia. A fundamental issue in understanding the relationship between neural activity and cardiac chronotropy is the identification of neuronal populations that control pacemaker cells. To date, most studies of neurocardiac control have been done in mammalian species, where neurons are embedded in and distributed throughout the heart, so they are largely inaccessible for whole-organ, integrative studies. Here, we establish the isolated, innervated zebrafish heart as a novel alternative model for studies of autonomic control of heart rate. Stimulation of individual cardiac vagosympathetic nerve trunks evoked bradycardia (parasympathetic activation) and tachycardia (sympathetic activation). Simultaneous stimulation of both vagosympathetic nerve trunks evoked a summative effect. Effects of nerve stimulation were mimicked by direct application of cholinergic and adrenergic agents. Optical mapping of electrical activity confirmed the sinoatrial region as the site of origin of normal pacemaker activity and identified a secondary pacemaker in the atrioventricular region. Strong vagosympathetic nerve stimulation resulted in a shift in the origin of initial excitation from the sinoatrial pacemaker to the atrioventricular pacemaker. Putative pacemaker cells in the sinoatrial and atrioventricular regions expressed adrenergic β2 and cholinergic muscarinic type 2 receptors. Collectively, we have demonstrated that the zebrafish heart contains the accepted hallmarks of vertebrate cardiac control, establishing this preparation as a viable model for studies of integrative physiological control of cardiac function by intracardiac neurons. PMID:27342878

Grain-resolved analysis of localized deformation in nickel-titanium wire under tensile load.

PubMed

Sedmák, P; Pilch, J; Heller, L; Kopeček, J; Wright, J; Sedlák, P; Frost, M; Šittner, P

2016-08-05

The stress-induced martensitic transformation in tensioned nickel-titanium shape-memory alloys proceeds by propagation of macroscopic fronts of localized deformation. We used three-dimensional synchrotron x-ray diffraction to image at micrometer-scale resolution the grain-resolved elastic strains and stresses in austenite around one such front in a prestrained nickel-titanium wire. We found that the local stresses in austenite grains are modified ahead of the nose cone-shaped buried interface where the martensitic transformation begins. Elevated shear stresses at the cone interface explain why the martensitic transformation proceeds in a localized manner. We established the crossover from stresses in individual grains to a continuum macroscopic internal stress field in the wire and rationalized the experimentally observed internal stress field and the topology of the macroscopic front by means of finite element simulations of the localized deformation. Copyright © 2016, American Association for the Advancement of Science.

Reticulated telangiectatic erythema of the pacemaker.

PubMed

Martin, Lucy K; Wendschuh, Philip; Wendschuh, Peter

2008-05-01

Reticulated telangiectatic erythema is a rare entity; it has been reported to occur following the placement of implanted cardiac devices and drug delivery systems. Histologically, reticulated telangiectatic erythema of the pacemaker is characterized by slight spongiosis and increased dermal telangiectasias. We describe a patient that developed reticulated telangiectatic nonpruritic patches on the left chest after the placement of a pacemaker. The patient responded favorably to the removal of the pacemaker.

Retrieval of the Leadless Cardiac Pacemaker: A Multicenter Experience.

PubMed

Reddy, Vivek Y; Miller, Marc A; Knops, Reinoud E; Neuzil, Petr; Defaye, Pascal; Jung, Werner; Doshi, Rahul; Castellani, Mark; Strickberger, Adam; Mead, R Hardwin; Doppalapudi, Harish; Lakkireddy, Dhanunjaya; Bennett, Matthew; Sperzel, Johannes

2016-12-01

Leadless cardiac pacemakers have emerged as a safe and effective alternative to conventional transvenous single-chamber ventricular pacemakers. Herein, we report a multicenter experience on the feasibility and safety of acute retrieval (<6 weeks) and chronic retrieval (>6 weeks) of the leadless cardiac pacemaker in humans. This study included patients enrolled in 3 multicenter trials, who received a leadless cardiac pacemaker implant and who subsequently underwent a device removal attempt. The overall leadless pacemaker retrieval success rate was 94%: for patients whose leadless cardiac pacemaker had been implanted for <6 weeks (acute retrieval cohort), complete retrieval was achieved in 100% (n=5/5); for those implanted for ≥ 6 weeks (chronic retrieval cohort), retrieval was achieved in 91% (n=10/11) of patients. The mean duration of time from implant to retrieval attempt was 346 days (range, 88-1188 days) in the chronic retrieval cohort, and nearly two thirds (n=7; 63%) had been implanted for >6 months before the retrieval attempt. There were no procedure-related adverse events at 30 days post retrieval procedure. This multicenter experience demonstrated the feasibility and safety of retrieving a chronically implanted single-chamber (right ventricle) active fixation leadless pacemaker. URL: https://www.clinicaltrials.gov. Unique identifiers: NCT02051972, NCT02030418, and NCT01700244. © 2016 American Heart Association, Inc.

Influence of digital and analogue cellular telephones on implanted pacemakers.

PubMed

Altamura, G; Toscano, S; Gentilucci, G; Ammirati, F; Castro, A; Pandozi, C; Santini, M

1997-10-01

The aim of this study was to find out whether digital and analogue cellular 'phones affect patients with pacemakers. The study comprised continuous ECG monitoring of 200 pacemaker patients. During the monitoring certain conditions caused by interference created by the telephone were looked for: temporary or prolonged pacemaker inhibition; a shift to asynchronous mode caused by electromagnetic interference; an increase in ventricular pacing in dual chamber pacemakers, up to the programmed upper rate. The Global System for Mobile Communications system interfered with pacing 97 times in 43 patients (21.5%). During tests on Total Access of Communication System telephones, there were 60 cases of pacing interference in 35 patients (17.5%). There were 131 interference episodes during ringing vs 26 during the on/off phase; (P < 0.0001); 106 at maximum sensitivity level vs 51 at the 'base' value; P < 0.0001). Prolonged pacing inhibition (> 4 s) was seen at the pacemaker 'base' sensing value in six patients using the Global system but in only one patient using Total Access. Cellular 'phones may be dangerous for pacemaker patients. However, they can be used safely if patients do not carry the 'phone close to the pacemaker, which is the only place where high risk interference has been observed.

Pacemaker therapy in low-birth-weight infants.

PubMed

Fuchigami, Tai; Nishioka, Masahiko; Akashige, Toru; Shimabukuro, Atsuya; Nagata, Nobuhiro

2018-02-01

Infants born with complete atrioventricular block (CAVB) and fetal bradycardia are frequently born with low birth weight. Three low-birth-weight CAVB infants underwent temporary pacemaker implantation, followed by permanent single-chamber pacemaker implantation at median body weights of 1.7 and 3.2 kg, respectively. All infants caught up with their growth curves and had >3 years of estimated residual battery life. This two-stage strategy was successful in facilitating permanent pacemaker implantation in low-birth-weight babies. Placement of single-chamber pacemaker on the apex of the left ventricle appears to be associated with longer battery lifespan. © 2018 Wiley Periodicals, Inc.

Effect on pacemakers of airport weapons detectors

PubMed Central

Johnson, David L.

1974-01-01

An investigation was carried out using a variety of pacemakers and all the types of weapons detectors in common use in Canada, to determine whether or not such detectors present a hazard to pacemaker bearers. The results indicate that only left-side implants of unipolar sensing pacemakers are likely to be affected, that ventricular fibrillation initiated by interference-induced competitive pacing is the only conceivable hazard, but that the probability of 10−9 for the occurrence of this event is so low that it may be completely disregarded. Physicians may therefore reassure pacemaker bearers of their safety in and around airport weapons detectors. ImagesFIG. 1 PMID:4825148

Advanced Pacemaker

NASA Technical Reports Server (NTRS)

1990-01-01

Synchrony, developed by St. Jude Medical's Cardiac Rhythm Management Division (formerly known as Pacesetter Systems, Inc.) is an advanced state-of-the-art implantable pacemaker that closely matches the natural rhythm of the heart. The companion element of the Synchrony Pacemaker System is the Programmer Analyzer APS-II which allows a doctor to reprogram and fine tune the pacemaker to each user's special requirements without surgery. The two-way communications capability that allows the physician to instruct and query the pacemaker is accomplished by bidirectional telemetry. APS-II features 28 pacing functions and thousands of programming combinations to accommodate diverse lifestyles. Microprocessor unit also records and stores pertinent patient data up to a year.

Space Derived Health Aids (Cardiac Pacemaker)

NASA Technical Reports Server (NTRS)

1981-01-01

St. Jude Medical's Cardiac Rhythm Management Division's (formerly known as Pacesetter Systems, Inc.) pacer is a rechargeable cardiac pacemaker that eliminates the recurring need for surgery to implant a new battery. The Programalith is an advanced cardiac pacing system which permits a physician to reprogram a patient's implanted pacemaker without surgery. System consists of a pacemaker, together with a physician's console containing the programmer and a data printer. Signals are transmitted by wireless telemetry. Two-way communications, originating from spacecraft electrical power systems technology, allows physician to interrogate the pacemaker as to the status of the heart, then to fine tune the device to best suit the patient's needs.

Cortical Composition Hierarchy Driven by Spine Proportion Economical Maximization or Wire Volume Minimization

PubMed Central

Karbowski, Jan

2015-01-01

The structure and quantitative composition of the cerebral cortex are interrelated with its computational capacity. Empirical data analyzed here indicate a certain hierarchy in local cortical composition. Specifically, neural wire, i.e., axons and dendrites take each about 1/3 of cortical space, spines and glia/astrocytes occupy each about (1/3)2, and capillaries around (1/3)4. Moreover, data analysis across species reveals that these fractions are roughly brain size independent, which suggests that they could be in some sense optimal and thus important for brain function. Is there any principle that sets them in this invariant way? This study first builds a model of local circuit in which neural wire, spines, astrocytes, and capillaries are mutually coupled elements and are treated within a single mathematical framework. Next, various forms of wire minimization rule (wire length, surface area, volume, or conduction delays) are analyzed, of which, only minimization of wire volume provides realistic results that are very close to the empirical cortical fractions. As an alternative, a new principle called “spine economy maximization” is proposed and investigated, which is associated with maximization of spine proportion in the cortex per spine size that yields equally good but more robust results. Additionally, a combination of wire cost and spine economy notions is considered as a meta-principle, and it is found that this proposition gives only marginally better results than either pure wire volume minimization or pure spine economy maximization, but only if spine economy component dominates. However, such a combined meta-principle yields much better results than the constraints related solely to minimization of wire length, wire surface area, and conduction delays. Interestingly, the type of spine size distribution also plays a role, and better agreement with the data is achieved for distributions with long tails. In sum, these results suggest that for the efficiency of local circuits wire volume may be more primary variable than wire length or temporal delays, and moreover, the new spine economy principle may be important for brain evolutionary design in a broader context. PMID:26436731

Pacemakers and Implantable Defibrillators - Multiple Languages

MedlinePlus

... Multiple Languages → All Health Topics → Pacemakers and Implantable Defibrillators URL of this page: https://medlineplus.gov/languages/ ... List of All Topics All Pacemakers and Implantable Defibrillators - Multiple Languages To use the sharing features on ...

Selective interference with pacemaker activity by electrical dental devices.

PubMed

Miller, C S; Leonelli, F M; Latham, E

1998-01-01

We sought to determine whether electromagnetic interference with cardiac pacemakers occurs during the operation of contemporary electrical dental equipment. Fourteen electrical dental devices were tested in vitro for their ability to interfere with the function of two Medtronics cardiac pacemakers (one a dual-chamber, bipolar Thera 7942 pacemaker, the other a single-chamber, unipolar Minix 8340 pacemaker). Atrial and ventricular pacemaker output and electrocardiographic activity were monitored by means of telemetry with the use of a Medtronics 9760/90 programmer. Atrial and ventricular pacing were inhibited by electromagnetic interference produced by the electrosurgical unit up to a distance of 10 cm, by the ultrasonic bath cleaner up to 30 cm, and by the magnetorestrictive ultrasonic scalers up to 37.5 cm. In contrast, operation of the amalgamator, electric pulp tester, composite curing light, dental handpieces, electric toothbrush, microwave oven, dental chair and light, ENAC ultrasonic instrument, radiography unit, and sonic scaler did not alter pacing rate or rhythm. These results suggest that certain electrosurgical and ultrasonic instruments may produce deleterious effects in medically fragile patients with cardiac pacemakers.

Prediction of significant conduction disease through noninvasive assessment of cardiac calcification.

PubMed

Mainigi, Sumeet K; Chebrolu, Lakshmi Hima Bindu; Romero-Corral, Abel; Mehta, Vinay; Machado, Rodolfo Rozindo; Konecny, Tomas; Pressman, Gregg S

2012-10-01

Cardiac calcification is associated with coronary artery disease, arrhythmias, conduction disease, and adverse cardiac events. Recently, we have described an echocardiographic-based global cardiac calcification scoring system. The objective of this study was to evaluate the severity of cardiac calcification in patients with permanent pacemakers as based on this scoring system. Patients with a pacemaker implanted within the 2-year study period with a previous echocardiogram were identified and underwent blinded global cardiac calcium scoring. These patients were compared to matched control patients without a pacemaker who also underwent calcium scoring. The study group consisted of 49 patients with pacemaker implantation who were compared to 100 matched control patients. The mean calcium score in the pacemaker group was 3.3 ± 2.9 versus 1.8 ± 2.0 (P = 0.006) in the control group. Univariate and multivariate analysis revealed glomerular filtration rate and calcium scoring to be significant predictors of the presence of a pacemaker. Echocardiographic-based calcium scoring correlates with the presence of severe conduction disease requiring a pacemaker. © 2012, Wiley Periodicals, Inc.

Development of pacemaker properties and rhythmogenic mechanisms in the mouse embryonic respiratory network

PubMed Central

Chevalier, Marc; Toporikova, Natalia; Simmers, John; Thoby-Brisson, Muriel

2016-01-01

Breathing is a vital rhythmic behavior generated by hindbrain neuronal circuitry, including the preBötzinger complex network (preBötC) that controls inspiration. The emergence of preBötC network activity during prenatal development has been described, but little is known regarding inspiratory neurons expressing pacemaker properties at embryonic stages. Here, we combined calcium imaging and electrophysiological recordings in mouse embryo brainstem slices together with computational modeling to reveal the existence of heterogeneous pacemaker oscillatory properties relying on distinct combinations of burst-generating INaP and ICAN conductances. The respective proportion of the different inspiratory pacemaker subtypes changes during prenatal development. Concomitantly, network rhythmogenesis switches from a purely INaP/ICAN-dependent mechanism at E16.5 to a combined pacemaker/network-driven process at E18.5. Our results provide the first description of pacemaker bursting properties in embryonic preBötC neurons and indicate that network rhythmogenesis undergoes important changes during prenatal development through alterations in both circuit properties and the biophysical characteristics of pacemaker neurons. DOI: http://dx.doi.org/10.7554/eLife.16125.001 PMID:27434668

Involvement of mitochondrial Na+–Ca2+ exchange in intestinal pacemaking activity

PubMed Central

Kim, Byung Joo; Jun, Jae Yeoul; So, Insuk; Kim, Ki Whan

2006-01-01

AIM: Interstitial cells of Cajal (ICCs) are the pacemaker cells that generate slow waves in the gastrointestinal (GI) tract. We have aimed to investigate the involvement of mitochondrial Na+-Ca2+ exchange in intestinal pacemaking activity in cultured interstitial cells of Cajal. METHODS: Enzymatic digestions were used to dissociate ICCs from the small intestine of a mouse. The whole-cell patch-clamp configuration was used to record membrane currents (voltage clamp) and potentials (current clamp) from cultured ICCs. RESULTS: Clonazepam and CGP37157 inhibited the pacemaking activity of ICCs in a dose-dependent manner. Clonazepam from 20 to 60 µmol/L and CGP37157 from 10 to 30 µmol/L effectively inhibited Ca2+ efflux from mitochondria in pacemaking activity of ICCs. The IC50s of clonazepam and CGP37157 were 37.1 and 18.2 µmol/L, respectively. The addition of 20 µmol/L NiCl2 to the internal solution caused a “wax and wane” phenomenon of pacemaking activity of ICCs. CONCLUSION: These results suggest that mitochondrial Na+-Ca2+ exchange has an important role in intestinal pacemaking activity. PMID:16521198

Direct conformational analysis of a 10 nm long oligothiophene wire.

PubMed

Nishiyama, Fumitaka; Ogawa, Kengo; Tanaka, Shoji; Yokoyama, Takashi

2008-05-01

Conformational variations of a 10 nm long oligothiophene wire comprising 24 thiophene rings on Au(111), which are related to the various straight and bent shapes of the long wires, have been directly visualized by scanning tunneling microscopy (STM). The local bending angles within the wire are well characterized as s-cis/s-trans configurations of individual thiophene rings. We find that the partial stabilization of the metastable s-cis conformation results in the wire bending, which should be influenced by solvent and substituents.

1978 Pacemaker Newspaper Awards: What Makes a Pacemaker?

ERIC Educational Resources Information Center

Brasler, Wayne

1979-01-01

Lists the nine high school and college newspapers, and the one newsmagazine, that won Pacemaker Awards in 1978; discusses characteristics that make each of them outstanding, and provides reproductions of a front page from each publication. (GT)

Stem cells as biological heart pacemakers.

PubMed

Gepstein, Lior

2005-12-01

Abnormalities in the pacemaker function of the heart or in cardiac impulse conduction may result in the appearance of a slow heart rate, traditionally requiring the implantation of a permanent electronic pacemaker. In recent years, a number of experimental approaches have been developed in an attempt to generate biological alternatives to implantable electronic devices. These strategies include, initially, a number of gene therapy approaches (aiming to manipulate the expression of ionic currents or their modulators and thereby convert quiescent cardiomyocytes into pacemaking cells) and, more recently, the use of cell therapy and tissue engineering. The latter approach explored the possibility of grafting pacemaking cells, either derived directly during the differentiation of human embryonic stem cells or engineered from mesenchymal stem cells, into the myocardium. This review will describe each of these approaches, focusing mainly on the stem cell strategies, their possible advantages and shortcomings, as well as the avenues required to make biological pacemaking a clinical reality.

Gene- and cell-based bio-artificial pacemaker: what basic and translational lessons have we learned?

PubMed Central

Li, RA

2012-01-01

Normal rhythms originate in the sino-atrial node, a specialized cardiac tissue consisting of only a few thousands of pacemaker cells. Malfunction of pacemaker cells due to diseases or aging leads to rhythm generation disorders (for example, bradycardias and sick-sinus syndrome (SSS)), which often necessitate the implantation of electronic pacemakers. Although effective, electronic devices are associated with such shortcomings as limited battery life, permanent implantation of leads, lead dislodging, the lack of autonomic responses and so on. Here, various gene- and cell-based approaches, with a particular emphasis placed on the use of pluripotent stem cells and the hyperpolarization-activated cyclic nucleotide-gated-encoded pacemaker gene family, that have been pursued in the past decade to reconstruct bio-artificial pacemakers as alternatives will be discussed in relation to the basic biological insights and translational regenerative potential. PMID:22673497

Gene- and cell-based bio-artificial pacemaker: what basic and translational lessons have we learned?

PubMed

Li, R A

2012-06-01

Normal rhythms originate in the sino-atrial node, a specialized cardiac tissue consisting of only a few thousands of nodal pacemaker cells. Malfunction of pacemaker cells due to diseases or aging leads to rhythm generation disorders (for example, bradycardias and sick-sinus syndrome (SSS)), which often necessitate the implantation of electronic pacemakers. Although effective, electronic devices are associated with such shortcomings as limited battery life, permanent implantation of leads, lead dislodging, the lack of autonomic responses and so on. Here, various gene- and cell-based approaches, with a particular emphasis placed on the use of pluripotent stem cells and the hyperpolarization-activated cyclic nucleotide-gated-encoded pacemaker gene family, that have been pursued in the past decade to reconstruct bio-artificial pacemakers as alternatives will be discussed in relation to the basic biological insights and translational regenerative potential.

Biofilm on artificial pacemaker: fiction or reality?

PubMed

Santos, Ana Paula Azevedo; Watanabe, Evandro; Andrade, Denise de

2011-11-01

Cardiac pacing through cardiac pacemaker is one of the most promising alternatives in the treatment of arrhythmias, but it can cause reactions natural or complex reactions, either early or late. This study aimed to describe the scientific evidence on the risk of infection and biofilm formation associated with cardiac pacemaker. This is a study of integrative literature review. It included 14 publications classified into three thematic categories: diagnosis (microbiological and/or clinical), complications and therapy of infections. Staphylococcus epidermidis and Staphylococcus aureus were the microorganisms most frequently isolated. It was not possible to determine the incidence of infection associated with pacemakers, since the studies were generally of prevalence. In terms of therapy, the complete removal of pacemakers stood out, especially in cases of suspected biofilm. Still controversial is the use of systemic antibiotic prophylaxis in reducing the incidence of infection associated with implantation of a pacemaker.

Case of pacemaker pocket infection caused by Finegoldia magna.

PubMed

Hosseini Dehkordi, Seyed Hamed; Osorio, Georgina

2017-10-01

Finegoldia magna (formerly called Peptostreptococcus magnus) is a Gram-positive anaerobic coccus which is increasingly recognized as an opportunistic pathogen. We present a case of F. magna associated non-valvular cardiovascular device-related infection in an 83 year-old male who received a permanent pacemaker for sick sinus syndrome seven weeks prior to his presentation. Five weeks after the implantation, the pacemaker and leads were explanted because of clinical evidence of pacemaker pocket infection. He was initially treated with sulfamethoxazole-trimethoprim based on the Gram stain results from the removed pacemaker. However, two weeks later, he was readmitted with sepsis and was successfully treated with ampicillin-sulbactam. Culture results from the pacemaker and pocket as well as blood cultures grew F. magna. Clinicians should be aware of the possibility of F. magna infection when initial gram stain results show "gram positive cocci". Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of high-intensity power-frequency electric fields on implanted modern multiprogrammable cardiac pacemakers.

PubMed

Butrous, G S; Meldrum, S J; Barton, D G; Male, J C; Bonnell, J A; Camm, A J

1982-05-01

The effect on an implanted, multiprogrammable pacemaker of power-frequency (50 Hz) electric fields up to an intensity (unperturbed value measured at 1.7 m) of 20 kV/m were assessed in ten paced patients. Radiotelemetric monitoring of the electrocardiogram allowed supervision of the electrocardiogram throughout exposure to the alternating electric field. Displacement body currents of up to 300μA were achieved depending on the position and height of the patient. None of the pacemakers was inhibited, triggered or reverted to fixed rate operation during the exposure. The programmable functions, programmability or output characteristics were not affected. Small changes in cardiac rate and rhythm elicited the correct pacemaker responses. Unlike earlier models of pacemaker, this modern implanted pacemaker, which represents `the state of the art', is not affected by 50 Hz electric fields likely to be encountered when standing underneath power lines.

Central Vein Dilatation Prior to Concomitant Port Implantation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krombach, Gabriele A., E-mail: krombach@rad.rwth-aachen.de; Plumhans, Cedric; Goerg, Fabian

2010-04-15

Implantation of subcutaneous port systems is routinely performed in patients requiring repeated long-term infusion therapy. Ultrasound- and fluoroscopy-guided implantation under local anesthesia is broadly established in interventional radiology and has decreased the rate of complications compared to the surgical approach. In addition, interventional radiology offers the unique possibility of simultaneous management of venous occlusion. We present a technique for recanalization of central venous occlusion and angioplasty combined with port placement in a single intervention which we performed in two patients. Surgical port placement was impossible owing to occlusion of the superior vena cava following placement of a cardiac pacemaker andmore » occlusion of multiple central veins due to paraneoplastic coagulopathy, respectively. In both cases the affected vessel segments were dilated with balloon catheters and the port systems were placed thereafter. After successful dilatation, the venous access was secured with a 25-cm-long, 8-Fr introducer sheath, a subcutaneous pocket prepared, and the port catheter tunneled to the venipuncture site. The port catheter was introduced through the sheath with the proximal end connected to a 5-Fr catheter. This catheter was pulled through the tunnel in order to preserve the tunnel and, at the same time, allow safe removal of the long sheath over the wire. The port system functioned well in both cases. The combination of recanalization and port placement in a single intervention is a straightforward alternative for patients with central venous occlusion that can only be offered by interventional radiology.« less

Deformable known component model-based reconstruction for coronary CT angiography

NASA Astrophysics Data System (ADS)

Zhang, X.; Tilley, S.; Xu, S.; Mathews, A.; McVeigh, E. R.; Stayman, J. W.

2017-03-01

Purpose: Atherosclerosis detection remains challenging in coronary CT angiography for patients with cardiac implants. Pacing electrodes of a pacemaker or lead components of a defibrillator can create substantial blooming and streak artifacts in the heart region, severely hindering the visualization of a plaque of interest. We present a novel reconstruction method that incorporates a deformable model for metal leads to eliminate metal artifacts and improve anatomy visualization even near the boundary of the component. Methods: The proposed reconstruction method, referred as STF-dKCR, includes a novel parameterization of the component that integrates deformation, a 3D-2D preregistration process that estimates component shape and position, and a polyenergetic forward model for x-ray propagation through the component where the spectral properties are jointly estimated. The methodology was tested on physical data of a cardiac phantom acquired on a CBCT testbench. The phantom included a simulated vessel, a metal wire emulating a pacing lead, and a small Teflon sphere attached to the vessel wall, mimicking a calcified plaque. The proposed method was also compared to the traditional FBP reconstruction and an interpolation-based metal correction method (FBP-MAR). Results: Metal artifacts presented in standard FBP reconstruction were significantly reduced in both FBP-MAR and STF- dKCR, yet only the STF-dKCR approach significantly improved the visibility of the small Teflon target (within 2 mm of the metal wire). The attenuation of the Teflon bead improved to 0.0481 mm-1 with STF-dKCR from 0.0166 mm-1 with FBP and from 0.0301 mm-1 with FBP-MAR - much closer to the expected 0.0414 mm-1. Conclusion: The proposed method has the potential to improve plaque visualization in coronary CT angiography in the presence of wire-shaped metal components.

A fully implantable pacemaker for the mouse: from battery to wireless power.

PubMed

Laughner, Jacob I; Marrus, Scott B; Zellmer, Erik R; Weinheimer, Carla J; MacEwan, Matthew R; Cui, Sophia X; Nerbonne, Jeanne M; Efimov, Igor R

2013-01-01

Animal models have become a popular platform for the investigation of the molecular and systemic mechanisms of pathological cardiovascular physiology. Chronic pacing studies with implantable pacemakers in large animals have led to useful models of heart failure and atrial fibrillation. Unfortunately, molecular and genetic studies in these large animal models are often prohibitively expensive or not available. Conversely, the mouse is an excellent species for studying molecular mechanisms of cardiovascular disease through genetic engineering. However, the large size of available pacemakers does not lend itself to chronic pacing in mice. Here, we present the design for a novel, fully implantable wireless-powered pacemaker for mice capable of long-term (>30 days) pacing. This design is compared to a traditional battery-powered pacemaker to demonstrate critical advantages achieved through wireless inductive power transfer and control. Battery-powered and wireless-powered pacemakers were fabricated from standard electronic components in our laboratory. Mice (n = 24) were implanted with endocardial, battery-powered devices (n = 14) and epicardial, wireless-powered devices (n = 10). Wireless-powered devices were associated with reduced implant mortality and more reliable device function compared to battery-powered devices. Eight of 14 (57.1%) mice implanted with battery-powered pacemakers died following device implantation compared to 1 of 10 (10%) mice implanted with wireless-powered pacemakers. Moreover, device function was achieved for 30 days with the wireless-powered device compared to 6 days with the battery-powered device. The wireless-powered pacemaker system presented herein will allow electrophysiology studies in numerous genetically engineered mouse models as well as rapid pacing-induced heart failure and atrial arrhythmia in mice.

A Single Center Study of 1,179 Heart Transplant Patients-Factors Affecting Pacemaker Implantation.

PubMed

Wellmann, Petra; Herrmann, Florian Ernst Martin; Hagl, Christian; Juchem, Gerd

2017-03-01

After around 10% of heart transplant patients require pacemaker implantation. The bradyarrhythmias causing pacemaker requirement include sinus node dysfunction (SND) and atrioventricular block (AVB). This study sought to define clinical predictors for pacemaker requirement as well as identify differences in the patient groups developing SND and AVB. Our operative database was used to collect retrospective recipient, donor, and operative data of all patients receiving orthotopic heart transplants between 1981 and 2016. In the 35-year period 1,179 transplants were performed (mean recipient age 45.5 ± 0.5 years, 20.4% female, 90.6% biatrial technique) with bradyarrhythmias requiring pacemaker implantation developing in 135 patients (11.5%). Independent risk factors were prolonged operative time 340 minutes versus 313 minutes (P = 0.027) and a biatrial anastomosis (P = 0.036). Ischemia time, cardiopulmonary bypass time, aortic cross clamp time, and reperfusion time all had no significant effect on pacemaker implantation rates. Similarly, whether the transplant was a reoperation, a retransplant, or performed after primary assist implantation had no effects on pacemaker implantation rates. There was no survival difference between the paced and nonpaced groups. The donor age was higher in the patients who developed AVB as the indication for pacemaker implantation (43 vs 34 years, P = 0.031). Patients with AVB had longer aortic cross clamp times and developed the arrhythmia later than those who developed SND. Use of the bicaval instead of the biatrial technique and shortened operative times should reduce pacemaker requirement after heart transplantation. Survival is not affected by this complication. © 2017 Wiley Periodicals, Inc.

Frequency of pacemaker malfunction associated with monopolar electrosurgery during pulse generator replacement or upgrade surgery.

PubMed

Lin, Yun; Melby, Daniel P; Krishnan, Balaji; Adabag, Selcuk; Tholakanahalli, Venkatakrishna; Li, Jian-Ming

2017-08-01

The aim of this study is to investigate the frequency of electrosurgery-related pacemaker malfunction. A retrospective study was conducted to investigate electrosurgery-related pacemaker malfunction in consecutive patients undergoing pulse generator (PG) replacement or upgrade from two large hospitals in Minneapolis, MN between January 2011 and January 2014. The occurrence of this pacemaker malfunction was then studied by using MAUDE database for all four major device vendors. A total of 1398 consecutive patients from 2 large tertiary referral centers in Minneapolis, MN undergoing PG replacement or upgrade surgery were retrospectively studied. Four patients (0.3% of all patients), all with pacemakers from St Jude Medical (2.8%, 4 of 142) had output failure or inappropriately low pacing rate below 30 bpm during electrosurgery, despite being programmed in an asynchronous mode. During the same period, 1174 cases of pacemaker malfunctions were reported on the same models in MAUDE database, 37 of which (3.2%) were electrosurgery-related. Twenty-four cases (65%) had output failure or inappropriate low pacing rate. The distribution of adverse events was loss of pacing (59.5%), reversion to backup pacing (32.4%), inappropriate low pacing rate (5.4%), and ventricular fibrillation (2.7%). The majority of these (78.5%) occurred during PG replacement at ERI or upgrade surgery. No electrosurgery-related malfunction was found in MAUDE database on 862 pacemaker malfunction cases during the same period from other vendors. Electrosurgery during PG replacement or upgrade surgery can trigger output failure or inappropriate low pacing rate in certain models of modern pacemakers. Cautions should be taken for pacemaker-dependent patients.

The oral cavity is not a primary source for implantable pacemaker or cardioverter defibrillator infections

PubMed Central

2013-01-01

Background To test the hypothesis that the oral cavity is a potential source for implantable pacemaker and cardioverter defibrillators infections, the bacterial diversity on explanted rhythm heart management devices was investigated and compared to the oral microbiome. Methods A metagenomic approach was used to analyze the bacterial diversity on the surfaces of non-infected and infected pacemakers. The DNA from surfaces swaps of 24 non-infected and 23 infected pacemaker were isolated and subjected to bacterial-specific DNA amplification, single strand conformation polymorphism- (SSCP) and sequencing analysis. Species-specific primer sets were used to analyze for any correlation between bacterial diversity on pacemakers and in the oral cavity. Results DNA of bacterial origin was detected in 21 cases on infected pacemakers and assigned to the bacterial phylotypes Staphylococcus epidermidis, Propionibacterium acnes, Staphylococcus aureus, Staphylococcus schleiferi and Stapyhlococcus. In 17 cases bacterial DNA was found on pacemakers with no clinical signs of infections. On the basis of the obtained sequence data, the phylotypes Propionibacterium acnes, Staphylococcus and an uncultured bacterium were identified. Propionibacterium acnes and Staphylococcus epidermidis were the only bacteria detected in pacemeaker (n = 25) and oral samples (n = 11). Conclusions The frequency of the coincidental detection of bacteria on infected devices and in the oral cavity is low and the detected bacteria are highly abundant colonizers of non-oral human niches. The transmission of oral bacteria to the lead or device of implantable pacemaker or cardioverter defibrillators is unlikely relevant for the pathogenesis of pacemaker or cardioverter defibrillators infections. PMID:23575037

Is pacemaker therapy the right key to patients with vasovagal syncope?

PubMed

Radovanović, Nikola N; Kirćanski, Bratislav; Raspopović, Srdjan; Pavlović, Siniša U; Jovanović, Velibor; Milašinović, Goran

2016-01-01

Vasovagal syncope is the most common type of reflex syncope. Efficacy of cardiac pacing in this indication has not been the subject of many studies and pacemaker therapy in patients with vasovagal syncope is still controversial. This study aimed to assess the efficacy and safety of pacing therapy in treatment of patients with vasovagal syncope, to determine contribution of new therapeutic models in increasing its success, and to identify risk factors associated with a higher rate of symptoms after pacemaker implantation. A retrospective study included 30 patients with pacemaker implanted due to vasovagal syncope in the Pacemaker Center, Clinical Center of Serbia, between November 2003 and June 2014. Head-up tilt test was performed to diagnose vasovagal syncope. Patients with cardioinhibitory and mixed type of disease were enrolled in the study. Mean age was 48.1 ± 11.1 years and 18 (60%) patients were men. Mean follow-up period was 5.9 ± 3.0 years. Primarily, implantable loop recorder was implanted in 10 (33.3%) patients. Twenty (66.7%) patients presented cardioinhibitory and 10 (33.3%) mixed type of vasovagal syncope. After pacemaker implantation, 11 (36.7%) patients had syncope. In multiple logistic regression analysis we showed that syncope is statistically more likely to occur after pacemaker implantation in patients with mixed type of vasovagal syncope (p = 0.018). There were two (6.7%) perioperative surgical complications. Pacemaker therapy is a safe treatment for patients with vasovagal syncope, whose efficacy can be improved by strict selection of patients. We showed that symptoms occur statistically more often in patients with mixed type of disease after pacemaker implantation.

Low pacemaker incidence with continuous-sutured valves: a retrospective analysis.

PubMed

Niclauss, Lars; Delay, Dominique; Pfister, Raymond; Colombier, Sebastien; Kirsch, Matthias; Prêtre, René

2017-06-01

Background Permanent pacemaker implantation after surgical aortic valve replacement depends on patient selection and risk factors for conduction disorders. We aimed to identify risk criteria and obtain a selected group comparable to patients assigned to transcatheter aortic valve implantation. Methods Isolated sutured aortic valve replacements in 994 patients treated from 2007 to 2015 were reviewed. Demographics, hospital stay, preexisting conduction disorders, surgical technique, and etiology in patients with and without permanent pacemaker implantation were compared. Reported outcomes after transcatheter aortic valve implantation were compared with those of a subgroup including only degenerative valve disease and first redo. Results The incidence of permanent pacemaker implantation was 2.9%. Longer hospital stay ( p = 0.01), preexisting rhythm disorders ( p < 0.001), complex prosthetic endocarditis ( p = 0.01), and complex redo ( p < 0.001) were associated with permanent pacemaker implantation. Although prostheses were sutured with continuous monofilament in the majority of cases (86%), interrupted pledgetted sutures were used more often in the pacemaker group ( p = 0.002). In the subgroup analysis, the incidence of permanent pacemaker implantation was 2%; preexisting rhythm disorders and the suture technique were still major risk factors. Conclusion Permanent pacemaker implantation depends on etiology, preexisting rhythm disorders, and suture technique, and the 2% incidence compares favorably with the reported 5- to 10-fold higher incidence after transcatheter aortic valve implantation. Cost analysis should take this into account. Often dismissed as minor complication, permanent pacemaker implantation increases the risks of endocarditis, impaired myocardial recovery, and higher mortality if associated with prosthesis regurgitation.

Magnetic Resonance Imaging in Nondependent Pacemaker Patients with Pacemakers and Defibrillators with a Nearly Depleted Battery.

PubMed

Okamura, Hideo; Padmanabhan, Deepak; Watson, Robert E; Dalzell, Connie; Acker, Nancy; Jondal, Mary; Romme, Abby L; Cha, Yong-Mei; Asirvatham, Samuel J; Felmlee, Joel P; Friedman, Paul A

2017-05-01

Magnetic resonance imaging (MRI) in patients with non-MRI-conditional cardiac implantable electronic devices (CIEDs) has been shown to be safe when performed under closely monitored protocols. However, the safety of MRI in patients with devices with a nearly depleted battery has not been reported. Prospective data were collected between January 2008 and May 2015 in patients with non-MRI-conditional CIEDs undergoing clinically indicated MRI under institutional protocol. Patients who were pacemaker dependent were excluded. Patients whose devices were at elective replacement indicator (ERI) at the time of MRI or close to ERI (ERI or replacement for battery depletion within 3 months of scan) were identified through database review and analyzed for clinical events. MRI scans (n = 569) were performed in 442 patients. Of these, we identified 13 scans performed with a nearly depleted battery in nine patients. All scans with implantable cardioverter defibrillators (ICDs, n = 9) were uneventful. However, two scans with pacemakers close to ERI resulted in a power-on-reset (PoR) event. One scan with a pacemaker close to ERI that was programmed to DOO mode reached ERI during MRI and automatically changed to VVI mode. Additionally, one scan with a pacemaker at ERI did not allow programming. All pacemakers with events were implanted before 2005. Patients with pacemakers and ICDs with a nearly depleted battery can safely undergo MRI when patients are not pacemaker dependent. Attention should be paid because old devices can result in PoR or ERI during MRI, which may lead to oversensing and inhibition of pacing. © 2017 Wiley Periodicals, Inc.

Predicting spiral wave patterns from cell properties in a model of biological self-organization.

PubMed

Geberth, Daniel; Hütt, Marc-Thorsten

2008-09-01

In many biological systems, biological variability (i.e., systematic differences between the system components) can be expected to outrank statistical fluctuations in the shaping of self-organized patterns. In principle, the distribution of single-element properties should thus allow predicting features of such patterns. For a mathematical model of a paradigmatic and well-studied pattern formation process, spiral waves of cAMP signaling in colonies of the slime mold Dictyostelium discoideum, we explore this possibility and observe a pronounced anticorrelation between spiral waves and cell properties (namely, the firing rate) and particularly a clustering of spiral wave tips in regions devoid of spontaneously firing (pacemaker) cells. Furthermore, we observe local inhomogeneities in the distribution of spiral chiralities, again induced by the pacemaker distribution. We show that these findings can be explained by a simple geometrical model of spiral wave generation.

Pacemakers in large arrays of oscillators with nonlocal coupling

NASA Astrophysics Data System (ADS)

Jaramillo, Gabriela; Scheel, Arnd

2016-02-01

We model pacemaker effects of an algebraically localized heterogeneity in a 1 dimensional array of oscillators with nonlocal coupling. We assume the oscillators obey simple phase dynamics and that the array is large enough so that it can be approximated by a continuous nonlocal evolution equation. We concentrate on the case of heterogeneities with positive average and show that steady solutions to the nonlocal problem exist. In particular, we show that these heterogeneities act as a wave source. This effect is not possible in 3 dimensional systems, such as the complex Ginzburg-Landau equation, where the wavenumber of weak sources decays at infinity. To obtain our results we use a series of isomorphisms to relate the nonlocal problem to the viscous eikonal equation. We then use Fredholm properties of the Laplace operator in Kondratiev spaces to obtain solutions to the eikonal equation, and by extension to the nonlocal problem.

Predicting spiral wave patterns from cell properties in a model of biological self-organization

NASA Astrophysics Data System (ADS)

Geberth, Daniel; Hütt, Marc-Thorsten

2008-09-01

In many biological systems, biological variability (i.e., systematic differences between the system components) can be expected to outrank statistical fluctuations in the shaping of self-organized patterns. In principle, the distribution of single-element properties should thus allow predicting features of such patterns. For a mathematical model of a paradigmatic and well-studied pattern formation process, spiral waves of cAMP signaling in colonies of the slime mold Dictyostelium discoideum, we explore this possibility and observe a pronounced anticorrelation between spiral waves and cell properties (namely, the firing rate) and particularly a clustering of spiral wave tips in regions devoid of spontaneously firing (pacemaker) cells. Furthermore, we observe local inhomogeneities in the distribution of spiral chiralities, again induced by the pacemaker distribution. We show that these findings can be explained by a simple geometrical model of spiral wave generation.

Cardiac pacemaker dysfunction in children after thoracic drainage catheter manipulation.

PubMed

Lobdell, K W; Walters, H L; Hudson, C; Hakimi, M

1997-05-01

Two children underwent placement of permanent, epicardial-lead, dual-chamber, unipolar pacemaker systems for complete heart block. Postoperatively, both patients demonstrated subcutaneous emphysema-in the area of their pulse generators-temporally related to thoracic catheter manipulation. Acutely, each situation was managed with manual compression of the pulse generator, ascertaining appropriate pacemaker sensing and pacing. Maintenance of compression with pressure dressings, vigilant observation/monitoring, and education of the care givers resulted in satisfactory pacemaker function without invasive intervention.

Influence of internal current and pacing current on pacemaker longevity.

PubMed

Schuchert, A; Kuck, K H

1994-01-01

The effects of lower pulse amplitude on battery current and pacemaker longevity were studied comparing the new, small-sized VVI pacemaker, Minix 8341, with the former model, Pasys 8329. Battery current was telemetrically measured at 0.8, 1.6, 2.5, and 5.0 V pulse amplitude and 0.05, 0.25, 0.5, and 1.0 msec pulse duration. Internal current was assumed to be equal to the battery current at 0.8 V and 0.05 msec. Pacing current was calculated subtracting internal current from battery current. The Minix pacemaker had a significantly lower battery current because of a lower internal current (Minix: 4.1 +/- 0.1 microA; Pasys: 16.1 +/- 0.1 microA); pacing current of both units was similar. At 0.5 msec pulse duration, the programming from 5.0-2.5 V pulse amplitude resulted in a greater relative reduction of battery current in the newer pacemaker (51% vs 25%). Projected longevity of each pacemaker was 7.9 years at 5.0 V and 0.5 msec. The programming from 5.0-2.5 V extended the projected longevity by 2.3 years (Pasys) and by 7.1 years (Minix). The longevity was negligibly longer after programming to 1.6 V. extension of pacemaker longevity can be achieved with the programming to 2.5 V or less if the connected pacemakers need a low internal current for their circuitry.

Impact of Pacemaker Lead Characteristics on Pacemaker Related Infection and Heart Perforation: A Nationwide Population-Based Cohort Study.

PubMed

Lin, Yu-Sheng; Chen, Tien-Hsing; Hung, Sheng-Ping; Chen, Dong Yi; Mao, Chun-Tai; Tsai, Ming-Lung; Chang, Shih-Tai; Wang, Chun-Chieh; Wen, Ming-Shien; Chen, Mien-Cheng

2015-01-01

Several risk factors for pacemaker (PM) related complications have been reported. However, no study has investigated the impact of lead characteristics on pacemaker-related complications. Patients who received a new pacemaker implant from January 1997 to December 2011 were selected from the Taiwan National Health Insurance Database. This population was grouped according to the pacemaker lead characteristics in terms of fixation and insulation. The impact of the characteristics of leads on early heart perforation was analyzed by multivariable logistic regression analysis, while the impact of the lead characteristics on early and late infection and late heart perforation over a three-year period were analyzed using Cox regression. This study included 36,104 patients with a mean age of 73.4±12.5 years. In terms of both early and late heart perforations, there were no significant differences between groups across the different types of fixation and insulations. In the multivariable Cox regression analysis, the pacemaker-related infection rate was significantly lower in the active fixation only group compared to either the both fixation (OR, 0.23; 95% CI, 0.07-0.80; P = 0.020) or the passive fixation group (OR, 0.26; 95% CI, 0.08-0.83; P = 0.023). There was no difference in heart perforation between active and passive fixation leads. Active fixation leads were associated with reduced risk of pacemaker-related infection.

Transvenous permanent pacemaker implantation in dextrocardia: technique, challenges, outcome, and a brief review of literature.

PubMed

Shenthar, Jayaprakash; Rai, Maneesh K; Walia, Rohit; Ghanta, Somasekhar; Sreekumar, Praveen; Reddy, Satish S

2014-09-01

Dextrocardia is a rare congenital anomaly. Pacemaker implantation in dextrocardia can be challenging because of the distorted anatomy and associated anomalies. The literature regarding implantation of pacemaker in dextrocardia is scarce. The study involved retrospective analysis of records of patients with dextrocardia who had undergone pacemaker implantation between January 2006 and July 2013 from a single centre. Six patients with dextrocardia (five males and one female) underwent permanent pacemaker implantation (PPI) between January 2006 and July 2013. Of them, three had situs solitus dextrocardia and three situs inversus dextrocardia. All three patients with situs solitus dextrocardia had associated corrected transposition of great arteries. The indication for pacemaker implantation was symptomatic complete atrioventricular (AV) block in four, high-grade AV block in one, and sinus node dysfunction in one patient. A favourable outcome was noted during a mean follow-up of 3.9 years (4 months to 7 years) with one patient needing a pulse generator replacement. Permanent pacemaker implantation in dextrocardia can be challenging because of the distorted anatomy. Use of a technique employing angiography to delineate chamber anatomy and relationship can assist the operator during such difficult PPIs. The medium- and long-term survival after a successful pacemaker implantation in dextrocardia is favourable. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

[Analysis of pacemaker ECGs].

PubMed

Israel, Carsten W; Ekosso-Ejangue, Lucy; Sheta, Mohamed-Karim

2015-09-01

The key to a successful analysis of a pacemaker electrocardiogram (ECG) is the application of the systematic approach used for any other ECG without a pacemaker: analysis of (1) basic rhythm and rate, (2) QRS axis, (3) PQ, QRS and QT intervals, (4) morphology of P waves, QRS, ST segments and T(U) waves and (5) the presence of arrhythmias. If only the most obvious abnormality of a pacemaker ECG is considered, wrong conclusions can easily be drawn. If a systematic approach is skipped it may be overlooked that e.g. atrial pacing is ineffective, the left ventricle is paced instead of the right ventricle, pacing competes with intrinsic conduction or that the atrioventricular (AV) conduction time is programmed too long. Apart from this analysis, a pacemaker ECG which is not clear should be checked for the presence of arrhythmias (e.g. atrial fibrillation, atrial flutter, junctional escape rhythm and endless loop tachycardia), pacemaker malfunction (e.g. atrial or ventricular undersensing or oversensing, atrial or ventricular loss of capture) and activity of specific pacing algorithms, such as automatic mode switching, rate adaptation, AV delay modifying algorithms, reaction to premature ventricular contractions (PVC), safety window pacing, hysteresis and noise mode. A systematic analysis of the pacemaker ECG almost always allows a probable diagnosis of arrhythmias and malfunctions to be made, which can be confirmed by pacemaker control and can often be corrected at the touch of the right button to the patient's benefit.

Conduction disturbances after TAVR: Electrophysiological studies and pacemaker dependency.

PubMed

Makki, Nader; Dollery, Jenn; Jones, Danielle; Crestanello, Juan; Lilly, Scott

Permanent pacemaker (PPM) placement occurs in 5-20% of patients after transcatheter aortic valve replacement (TAVR). Although predictors of pacemaker implantation have been established, features that predispose patients to pacemaker utilization on follow up have not been widely reported. We performed a retrospective review of patients undergoing commercial TAVR between 2011 and 2016. We collated patients that underwent in-hospital PPM implantation and had a follow up of at least 3months. Data abstraction was performed for electrophysiological studies (EPS), pacemaker indication, timing, and device interrogation for pacemaker dependency on follow up. A total of 24 patients received in-hospital PPM post-TAVR (14% of total cohort), and mean follow up was 22months. Indications for PPM included resting complete heart block (CHB; 15/24, 63%), left bundle branch block and abnormal electrophysiological study (EPS; 7/24, 29%), alternating bundle branch block (1/24, 4%) and tachy-brady syndrome (1/24, 4%). Pacemaker dependency (underlying ventricular asystole, complete heart block, or >50% pacing) occurred in 8/24 patients (33%) during follow-up, 7 of whom had resting CHB, and one with CHB invoked during EPS. Pacemaker dependency after TAVR is common among those that exhibited CHB, but not among those with a prolonged HV delay during EPS. Although preliminary, these observations are relevant to management of rhythm disturbances after TAVR, and may inform the practice of EPS-based PPM implantation. Copyright © 2017 Elsevier Inc. All rights reserved.

Survival time with pacemaker implantation for dogs diagnosed with persistent atrial standstill.

PubMed

Cervenec, R M; Stauthammer, C D; Fine, D M; Kellihan, H B; Scansen, B A

2017-06-01

To evaluate survival time in dogs with persistent atrial standstill after pacemaker implantation and to compare the survival times for cardiac-related vs. non-cardiac deaths. Secondary objectives were to evaluate the effects of breed and the presence of congestive heart failure (CHF) at the time of diagnosis on survival time. Twenty dogs with persistent atrial standstill and pacemaker implantation. Medical records were searched to identify dogs diagnosed with persistent atrial standstill based on electrocardiogram that underwent pacemaker implantation. Survival after pacemaker implantation was analyzed using the Kaplan-Meier method. The median survival time after pacemaker implantation for all-cause mortality was 866 days. There was no significant difference (p=0.573) in median survival time for cardiac (506 days) vs. non-cardiac deaths (400 days). The presence of CHF at the time of diagnosis did not affect the survival time (P=0.854). No difference in median survival time was noted between breeds (P=0.126). Dogs with persistent atrial standstill have a median survival time of 866 days with pacemaker implantation, though a wide range of survival times was observed. There was no difference in the median survival time for dogs with cardiac-related deaths and those without. Patient breed and the presence of CHF before pacemaker implantation did not affect median survival time. Copyright © 2017 Elsevier B.V. All rights reserved.

Carbachol regulates pacemaker activities in cultured interstitial cells of Cajal from the mouse small intestine.

PubMed

So, Keum Young; Kim, Sang Hun; Sohn, Hong Moon; Choi, Soo Jin; Parajuli, Shankar Prasad; Choi, Seok; Yeum, Cheol Ho; Yoon, Pyung Jin; Jun, Jae Yeoul

2009-05-31

We studied the effect of carbachol on pacemaker currents in cultured interstitial cells of Cajal (ICC) from the mouse small intestine by muscarinic stimulation using a whole cell patch clamp technique and Ca2+-imaging. ICC generated periodic pacemaker potentials in the current-clamp mode and generated spontaneous inward pacemaker currents at a holding potential of-70 mV. Exposure to carbachol depolarized the membrane and produced tonic inward pacemaker currents with a decrease in the frequency and amplitude of the pacemaker currents. The effects of carbachol were blocked by 1-dimethyl-4-diphenylacetoxypiperidinium, a muscarinic M(3) receptor antagonist, but not by methotramine, a muscarinic M(2) receptor antagonist. Intracellular GDP-beta-S suppressed the carbachol-induced effects. Carbachol-induced effects were blocked by external Na+-free solution and by flufenamic acid, a non-selective cation channel blocker, and in the presence of thapsigargin, a Ca2+-ATPase inhibitor in the endoplasmic reticulum. However, carbachol still produced tonic inward pacemaker currents with the removal of external Ca2+. In recording of intracellular Ca2+ concentrations using fluo 3-AM dye, carbachol increased intracellular Ca2+ concentrations with increasing of Ca2+ oscillations. These results suggest that carbachol modulates the pacemaker activity of ICC through the activation of non-selective cation channels via muscarinic M(3) receptors by a G-protein dependent intracellular Ca2+ release mechanism.

Performance of re-used pacemakers and implantable cardioverter defibrillators compared with new devices at Groote Schuur Hospital in Cape Town, South Africa

PubMed Central

Jama, Zimasa V; Chin, Ashley; Mayosi, Bongani M; Badri, Motasim

2015-01-01

Objectives Little is known about the performance of re-used pacemakers and implantable cardioverter defibrillators (ICDs) in Africa. We sought to compare the risk of infection and the rate of malfunction of re-used pacemakers and ICDs with new devices implanted at Groote Schuur Hospital in Cape Town, South Africa. Methods This was a retrospective case comparison study of the performance of re-used pacemakers and ICDs in comparison with new devices implanted at Groote Schuur Hospital over a 10-year period. The outcomes were incidence of device infection, device malfunction, early battery depletion, and device removal due to infection, malfunction, or early battery depletion. Results Data for 126 devices implanted in 126 patients between 2003 and 2013 were analysed, of which 102 (81%) were pacemakers (51 re-used and 51 new) and 24 (19%) were ICDs (12 re-used and 12 new). There was no device infection, malfunction, early battery depletion or device removal in either the re-used or new pacemaker groups over the median follow up of 15.1 months [interquartile range (IQR), 1.3–36.24 months] for the re-used pacemakers, and 55.8 months (IQR, 20.3–77.8 months) for the new pacemakers. In the ICD group, no device infection occurred over a median follow up of 35.9 months (IQR, 17.0–70.9 months) for the re-used ICDs and 45.7 months (IQR, 37.6–53.7 months) for the new ICDs. One device delivered inappropriate shocks, which resolved without intervention and with no harm to the patient. This re-used ICD subsequently needed generator replacement 14 months later. In both the pacemaker and ICD groups, there were no procedure-non-related infections documented for the respective follow-up periods. Conclusion No significant differences were found in performance between re-used and new pacemakers and ICDs with regard to infection rates, device malfunction, battery life and device removal for complications. Pacemaker and ICD re-use is feasible and safe and is a viable option for patients with bradyarrhythmias and tachyarrthythmias. PMID:26407220

The use of plastic optical fibres and shape memory alloys for damage assessment and damping control in composite materials

NASA Astrophysics Data System (ADS)

Kuang, K. S. C.; Cantwell, W. J.

2003-08-01

This paper reports the use of a plastic fibre sensor for detecting impact damage in carbon fibre epoxy cantilever beams by monitoring their damping response under free vibration loading conditions. The composite beams were impacted at impact energies up to 8 J. The residual strengths and stiffnesses of the damaged laminates were measured in order to relate reductions in their mechanical properties to changes in their damping characteristics. Here, optical fibre sensors were surface bonded to carbon fibre composite beams which were subjected to free vibration tests to monitor their dynamic response. In the second part of this study, Ni-Ti shape memory alloy (SMA) wires were employed to control and modify the damping response of a composite beam. The SMA wires were initially trained to obtain the desired shape when activated. Here, the trained SMA wires were heated locally using a nickel/chromium wire that was wrapped around the trained region of the SMA. By using this method to activate the SMA wire (as opposed to direct electrical heating), it is possible to obtain localized actuation without heating the entire length of the wire. This procedure minimizes any damage to the host material that may result from local heat transfer between the SMA wire and the composite structure. In addition, the reduction in power requirements to achieve SMA activation permits the use of small-size power packs which can in turn lead to a potential weight reduction in weight-critical applications. The findings of this study demonstrate that a trained SMA offers a superior damping capability to that exhibited by an 'as-supplied' flat-annealed wire.

Localized end states in density modulated quantum wires and rings.

PubMed

Gangadharaiah, Suhas; Trifunovic, Luka; Loss, Daniel

2012-03-30

We study finite quantum wires and rings in the presence of a charge-density wave gap induced by a periodic modulation of the chemical potential. We show that the Tamm-Shockley bound states emerging at the ends of the wire are stable against weak disorder and interactions, for discrete open chains and for continuum systems. The low-energy physics can be mapped onto the Jackiw-Rebbi equations describing massive Dirac fermions and bound end states. We treat interactions via the continuum model and show that they increase the charge gap and further localize the end states. The electrons placed in the two localized states on the opposite ends of the wire can interact via exchange interactions and this setup can be used as a double quantum dot hosting spin qubits. The existence of these states could be experimentally detected through the presence of an unusual 4π Aharonov-Bohm periodicity in the spectrum and persistent current as a function of the external flux.

Quantum transport through disordered 1D wires: Conductance via localized and delocalized electrons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gopar, Víctor A.

Coherent electronic transport through disordered systems, like quantum wires, is a topic of fundamental and practical interest. In particular, the exponential localization of electron wave functions-Anderson localization-due to the presence of disorder has been widely studied. In fact, Anderson localization, is not an phenomenon exclusive to electrons but it has been observed in microwave and acoustic experiments, photonic materials, cold atoms, etc. Nowadays, many properties of electronic transport of quantum wires have been successfully described within a scaling approach to Anderson localization. On the other hand, anomalous localization or delocalization is, in relation to the Anderson problem, a less studiedmore » phenomenon. Although one can find signatures of anomalous localization in very different systems in nature. In the problem of electronic transport, a source of delocalization may come from symmetries present in the system and particular disorder configurations, like the so-called Lévy-type disorder. We have developed a theoretical model to describe the statistical properties of transport when electron wave functions are delocalized. In particular, we show that only two physical parameters determine the complete conductance distribution.« less

What Is a Pacemaker?

MedlinePlus

... your pacemaker. • If you work around industrial microwaves, electricity, cars or other large motors, ask your doctor about possible effects. Can I use a cell phone or microwave oven if I have a pacemaker? Microwave ovens, electric blankets, remote controls for TV and other common ...

21 CFR 870.3700 - Pacemaker programmers.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Pacemaker programmers. 870.3700 Section 870.3700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3700 Pacemaker programmers...

Of pacemakers and statistics: the actuarial method extended.

PubMed

Dussel, J; Wolbarst, A B; Scott-Millar, R N; Obel, I W

1980-01-01

Pacemakers cease functioning because of either natural battery exhaustion (nbe) or component failure (cf). A study of four series of pacemakers shows that a simple extension of the actuarial method, so as to incorporate Normal statistics, makes possible a quantitative differentiation between the two modes of failure. This involves the separation of the overall failure probability density function PDF(t) into constituent parts pdfnbe(t) and pdfcf(t). The approach should allow a meaningful comparison of the characteristics of different pacemaker types.

Self-Diagnostics Digitally Controlled Pacemaker/Defibrillators: A Design Plan for Incorporating Diagnostics and Digital Control in the schema of a Pacemaker/Defibrillator Design

DTIC Science & Technology

2005-09-01

of a system to store and retrieve digital/ wireless communication information from a pacemaker/ defibrillator, or other device , and to alert medical... wireless communication information from a pacemaker/defibrillator, or other device , and to alert medical personnel when a person is experiencing...with heart, pacing, program, test, sensor , circuit) where the individual needs immediate attention an audible alert will go off at the nurse’s

Automatic management of atrial and ventricular stimulation in a contemporary unselected population of pacemaker recipients: the ESSENTIAL Registry.

PubMed

Biffi, Mauro; Bertini, Matteo; Saporito, Davide; Belotti, Giuseppina; Quartieri, Fabio; Piancastelli, Maurizio; Pucci, Angelo; Boggian, Giulio; Mazzocca, Gian Franco; Giorgi, Davide; Diotallevi, Paolo; Diemberger, Igor; Martignani, Cristian; Pancaldi, Stefano; Ziacchi, Matteo; Marcantoni, Lina; Toselli, Tiziano; Attala, Simone; Iori, Matteo; Bottoni, Nicola; Argnani, Selina; Tomasi, Corrado; Sassone, Biagio; Boriani, Giuseppe

2016-10-01

We investigated the applicability of the Ventricular Capture Control (VCC) and Atrial Capture Control (ACC) algorithms for automatic management of cardiac stimulation featured by Biotronik pacemakers in a broad, unselected population of pacemaker recipients. Ventricular Capture Control and Atrial Capture Control were programmed to work at a maximum adapted output voltage as 4.8 V in consecutive recipients of Biotronik pacemakers. Ambulatory threshold measurements were made 1 and 12 months after pacemaker implant/replacement in all possible pacing/sensing configurations, and were compared with manual measurements. Among 542 patients aged 80 (73-85) years, 382 had a pacemaker implant and 160 a pacemaker replacement. Ventricular Capture Control could work at long term in 97% of patients irrespectively of pacing indication, lead type, and lead service life, performance being superior with discordant pacing/sensing configurations. Atrial Capture Control could work in 93% of patients at 4.8 V maximum adapted voltage and at any pulse width, regardless of pacing indication, lead type, and service life. At 12-month follow-up, a ventricular threshold increase ≥1.5 V had occurred in 4.4% of patients uneventfully owing to VCC functioning. Projected pacemaker longevity at 1 month was strongly correlated with the 12-month estimate, and exceeded 13 years in >60% of patients. These algorithms for automatic management of pacing output ensure patient safety in the event of a huge increase of pacing threshold, while enabling maximization of battery longevity. Their applicability is quite broad in an unselected pacemaker population irrespectively of lead choice and service of life. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

The influence of cholinesterase inhibitor therapy for dementia on risk of cardiac pacemaker insertion: a retrospective, population-based, health administrative databases study in Ontario, Canada.

PubMed

Huang, Allen R; Redpath, Calum J; van Walraven, Carl

2015-04-28

Cholinesterase inhibitors are used to treat the symptoms of dementia and can theoretically cause bradycardia. Previous studies suggest that patients taking these medications have an increased risk of undergoing pacemaker insertion. Since these drugs have a marginal impact on patient outcomes, it might be preferable to change drug treatment rather than implant a pacemaker. This population-based study determined the association of people with dementia exposed to cholinesterase inhibitor medication and pacemaker insertion. We used data from the Ontario health administrative databases from January 1, 1993 to June 30, 2012. We included all community-dwelling seniors who had a code for dementia and were exposed to cholinesterase inhibitors (donezepil, galantamine, and rivastigmine) and/or drugs used to treat co-morbidities of hypertension, diabetes, depression and hypothyroidism. We controlled for exposure to anti-arrhythmic drugs. Observation started at first exposure to any medication and continued until the earliest of pacemaker insertion, death, or end of study. 2,353,909 people were included with 96,000 (4.1%) undergoing pacemaker insertion during the observation period. Case-control analysis showed that pacemaker patients were less likely to be coded with dementia (unadjusted OR 0.42 [95%CI 0.41-0.42]) or exposed to cholinesterase inhibitors (unadjusted OR 0.39 [95%CI 0.37-0.41]). That Cohort analysis showed patients with dementia taking cholinesterase inhibitors had a decreased risk of pacemaker insertion (unadj-HR 0.58 [0.55-0.61]). Adjustment for patient age, sex, and other medications did not notably change results, as did restricting the analysis to incident users. Patients taking cholinesterase inhibitors rarely undergo, and have a significantly reduced risk of, cardiac pacemaker insertion.

Current use of implantable electrical devices in Sweden: data from the Swedish pacemaker and implantable cardioverter-defibrillator registry.

PubMed

Gadler, Fredrik; Valzania, Cinzia; Linde, Cecilia

2015-01-01

The National Swedish Pacemaker and Implantable Cardioverter-Defibrillator (ICD) Registry collects prospective data on all pacemaker and ICD implants in Sweden. We aimed to report the 2012 findings of the Registry concerning electrical devices implantation rates and changes over time, 1 year complications, long-term device longevity and patient survival. Forty-four Swedish implanting centres continuously contribute implantation of pacemakers and ICDs to the Registry by direct data entry on a specific website. Clinical and technical information on 2012 first implants and postoperative complications were analysed and compared with previous years. Patient survival data were obtained from the Swedish population register database. In 2012, the mean pacemaker and ICD first implantation rates were 697 and 136 per million inhabitants, respectively. The number of cardiac resynchronization therapy (CRT) first implantations/million capita was 41 (CRT pacemakers) and 55 (CRT defibrillators), with only a slight increase in CRT-ICD rate compared with 2011. Most device implantations were performed in men. Complication rates for pacemaker and ICD procedures were 5.3 and 10.1% at 1 year, respectively. Device and lead longevity differed among manufacturers. Pacemaker patients were older at the time of first implant and had generally worse survival rate than ICD patients (63 vs. 82% after 5 years). Pacemaker and ICD implantation rates seem to have reached a level phase in Sweden. Implantable cardioverter-defibrillator and CRT implantation rates are very low and do not reflect guideline indications. Gender differences in CRT and ICD implantations are pronounced. Device and patient survival rates are variable, and should be considered when deciding device type. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

A Fully Implantable Pacemaker for the Mouse: From Battery to Wireless Power

PubMed Central

Zellmer, Erik R.; Weinheimer, Carla J.; MacEwan, Matthew R.; Cui, Sophia X.; Nerbonne, Jeanne M.; Efimov, Igor R.

2013-01-01

Animal models have become a popular platform for the investigation of the molecular and systemic mechanisms of pathological cardiovascular physiology. Chronic pacing studies with implantable pacemakers in large animals have led to useful models of heart failure and atrial fibrillation. Unfortunately, molecular and genetic studies in these large animal models are often prohibitively expensive or not available. Conversely, the mouse is an excellent species for studying molecular mechanisms of cardiovascular disease through genetic engineering. However, the large size of available pacemakers does not lend itself to chronic pacing in mice. Here, we present the design for a novel, fully implantable wireless-powered pacemaker for mice capable of long-term (>30 days) pacing. This design is compared to a traditional battery-powered pacemaker to demonstrate critical advantages achieved through wireless inductive power transfer and control. Battery-powered and wireless-powered pacemakers were fabricated from standard electronic components in our laboratory. Mice (n = 24) were implanted with endocardial, battery-powered devices (n = 14) and epicardial, wireless-powered devices (n = 10). Wireless-powered devices were associated with reduced implant mortality and more reliable device function compared to battery-powered devices. Eight of 14 (57.1%) mice implanted with battery-powered pacemakers died following device implantation compared to 1 of 10 (10%) mice implanted with wireless-powered pacemakers. Moreover, device function was achieved for 30 days with the wireless-powered device compared to 6 days with the battery-powered device. The wireless-powered pacemaker system presented herein will allow electrophysiology studies in numerous genetically engineered mouse models as well as rapid pacing-induced heart failure and atrial arrhythmia in mice. PMID:24194832

Inward-rectifying potassium (Kir) channels regulate pacemaker activity in spinal nociceptive circuits during early life

PubMed Central

Li, Jie; Blankenship, Meredith L.; Baccei, Mark L.

2013-01-01

Pacemaker neurons in neonatal spinal nociceptive circuits generate intrinsic burst-firing and are distinguished by a lower “leak” membrane conductance compared to adjacent, non-bursting neurons. However, little is known about which subtypes of leak channels regulate the level of pacemaker activity within the developing rat superficial dorsal horn (SDH). Here we demonstrate that a hallmark feature of lamina I pacemaker neurons is a reduced conductance through inward-rectifying potassium (Kir) channels at physiological membrane potentials. Differences in the strength of inward rectification between pacemakers and non-pacemakers indicate the presence of functionally distinct Kir currents in these two populations at room temperature. However, Kir currents in both groups showed high sensitivity to block by extracellular Ba2+ (IC50 ~ 10 µM), which suggests the presence of ‘classical’ Kir (Kir2.x) channels in the neonatal SDH. The reduced Kir conductance within pacemakers is unlikely to be explained by an absence of particular Kir2.x isoforms, as immunohistochemical analysis revealed the expression of Kir2.1, Kir2.2 and Kir2.3 within spontaneously bursting neurons. Importantly, Ba2+ application unmasked rhythmic burst-firing in ~42% of non-bursting lamina I neurons, suggesting that pacemaker activity is a latent property of a sizeable population of SDH cells during early life. In addition, the prevalence of spontaneous burst-firing within lamina I was enhanced in the presence of high internal concentrations of free Mg2+, consistent with its documented ability to block Kir channels from the intracellular side. Collectively, the results indicate that Kir channels are key modulators of pacemaker activity in newborn central pain networks. PMID:23426663

Effect of monopolar radiofrequency energy on pacemaker function.

PubMed

Govekar, Henry R; Robinson, Thomas N; Varosy, Paul D; Girard, Guillaume; Montero, Paul N; Dunn, Christina L; Jones, Edward L; Stiegmann, Greg V

2012-10-01

This study aimed to quantify the clinical parameters of mono- and bipolar instruments that inhibit pacemaker function. The specific aims were to quantify pacer inhibition resulting from the monopolar instrument by altering the generator power setting, the generator mode, the distance between the active electrode and the pacemaker, and the location of the dispersive electrode. A transvenous ventricular lead pacemaker overdrive paced the native heart rate of an anesthetized pig. The primary outcome variable was pacer inhibition quantified as the number of beats dropped by the pacemaker during 5 s of monopolar active electrode activation. Lowering the generator power setting from 60 to 30 W decreased the number of dropped paced events (2.3 ± 1.2 vs 1.6 ± 0.8 beats; p = 0.045). At 30 W of power, use of the cut mode decreased the number of dropped paced beats compared with the coagulation mode (0.6 ± 0.5 vs 1.6 ± 0.8; p = 0.015). At 30 W coagulation, firing the active electrode at different distances from the pacemaker generator (3.75, 7.5, 15, and 30 cm) did not change the number of dropped paced beats (p = 0.314, analysis of variance [ANOVA]). The dispersive electrode was placed in four locations (right/left gluteus, right/left shoulder). More paced beats were dropped when the current vector traveled through the pacemaker/leads than when it did not (1.5 ± 1.0 vs 0.2 ± 0.4; p < 0.001). Clinical parameters that reduce the inhibition of a pacemaker by monopolar instruments include lowering the generator power setting, using cut (vs coagulation) mode, and locating the dispersive electrode so the current vector does not traverse the pacemaker generator or leads.

In vitro corrosion characteristics of commercially available orthodontic wires.

PubMed

Yonekura, Yasuyuki; Endo, Kazuhiko; Iijima, Masahiro; Ohno, Hiroki; Mizoguchi, Itaru

2004-06-01

The corrosion characteristics of orthodontic alloy wires were investigated both in as-received and grinded conditions in 0.9% NaCl solution by atomic absorption spectrophotometry and potentiodynamic polarization measurements. The amount of each metal ion released from most alloys was larger for the grinded wires than for the as-received wires (p<0.01). The fact that the beta-Ti alloy wire (Ti-Mo-Zr) does not contain allergenic metals such as Ni, Co, and Cr, and the finding that resistance to both general and localized corrosion is the highest among the six wires investigated suggest that this wire is the most biocompatible orthodontic wire. Since a small amount of Ni, Cr or Co ions were released from Ni-Ti, Co-Cr and stainless steel wires, special attention should be paid during their clinical use for patients with allergic tendencies.

Current facts on pacemaker electromagnetic interference and their application to clinical care

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sager, D.P.

1987-03-01

The development of the sensing demand cardiac pacemaker brought with it the problem of interference as a result of extraneous electric current and electromagnetic fields. This problem still deserves consideration, not only because harmful disruption of pacemaker function, while infrequent, can occur but also because myths and misunderstandings have flourished on the subject. Misinformation has often led to needless patient anxiety and unnecessary restrictions in activities of daily living. Similarly, when health care practitioners are misinformed about pacemaker interference, potentially hazardous situations can occur in the clinical environment. This article is a review of current information on the sources andmore » effects of electromagnetic interference (EMI) on pacemakers and includes a discussion of their application to patient care.« less

Congestive heart failure caused by transvenous pacemaker lead prolapse and associated right ventricular outflow tract obstruction in a dog.

PubMed

Djani, D M; Coleman, A E; Rapoport, G S; Schmiedt, C W; Layher, J; Thomason, J D

2016-12-01

A 16-year-old dog was presented for cough as well as increased respiratory rate and effort three years after implantation of a single-lead transvenous artificial pacemaker system. Thoracic radiographs and echocardiography disclosed prolapse of the pacemaker lead into the main pulmonary artery, causing severe pulmonary insufficiency and right-sided volume overload. Repositioning of the pacemaker lead led to improvement of pulmonary insufficiency and resolution of the dog's clinical signs and cavitary effusions. This case describes a late complication of pacemaker implantation that may be avoided by appropriate use of the manufacturer-provided anchoring sleeve and avoidance of excessive lead redundancy. Copyright © 2016 Elsevier B.V. All rights reserved.

Transcatheter leadless pacemaker implantation in a patient with a transvenous dual-chamber pacemaker already in place.

PubMed

Karjalainen, Pasi P; Nammas, Wail; Paana, Tuomas

2016-01-01

An 83-year-old lady had a DDDR pacemaker inserted in 1997 for symptomatic atrioventricular block. She underwent battery replacement in 2008. In 2010, she developed atrial fibrillation; the pacemaker was switched to VVIR mode. During the last 2years, ventricular lead threshold increased progressively. In December 2015, she presented for elective battery replacement. After successful battery replacement, the ventricular lead threshold remained high; therefore, we implanted a leadless transcatheter pacemaker, via femoral vein access, using a dedicated catheter delivery system. Electrical measurements at this stage revealed a pacing threshold of 0.28V at 0.24msec, and an impedance of 650Ω. Copyright © 2016 Elsevier Inc. All rights reserved.

Monitoring the radiation dose to a multiprogrammable pacemaker during radical radiation therapy: A case report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muller-Runkel, R.; Orsolini, G.; Kalokhe, U.P.

1990-11-01

Multiprogrammable pacemakers, using complimentary metaloxide semiconductor (CMOS) circuitry, may fail during radiation therapy. We report about a patient who received 6,400 cGy for unresectable carcinoma of the left lung. In supine treatment position, arms raised above the head, the pacemaker was outside the treated area by a margin of at least 1 cm, shielded by cerrobend blocking mounted on a tray. From thermoluminescent dosimeter (TLD) measurements, we estimate that the pacemaker received 620 cGy in scatter doses. Its function was monitored before, during, and after completion of radiation therapy. The pacemaker was functioning normally until the patient's death 5 monthsmore » after completion of treatment. The relevant electrocardiograms (ECGs) are presented.« less

Transfissural Route Used for Preoperative Localization of Small Pulmonary Lesions with a Short Hook Wire and Suture System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iguchi, Toshihiro, E-mail: iguchi@ba2.so-net.ne.jp; Hiraki, Takao, E-mail: takaoh@tc4.so-net.ne.jp; Gobara, Hideo, E-mail: gobara@cc.okayama-u.ac.jp

2015-02-15

PurposeWe retrospectively evaluated the results of the transfissural route for preoperative localization with a short hook wire and suture system for video-assisted thoracoscopic surgery (VATS).MethodsEleven patients with 11 tumors underwent CT-guided transfissural placement of a hook wire before VATS. This route was selected for all patients, because the distance between the tumor and interlobar fissure was much shorter than the required distance traversed using the conventional approach. Complications were evaluated using the National Cancer Institute Common Terminology Criteria for Adverse Events Version 4.0.ResultsThe hook wire was successfully placed using the transfissural route in all but one case. Of these tenmore » successful placements, two tumors needed a second puncture for optimal placement, because the CT scan showed that the first hook wire was not properly placed in the lung. In one patient, we did not attempt replacement after the first placement was incorrect. In ten successful procedures, the mean distance traversed in the parenchyma of the unaffected lung lobe was 27.9 mm. The distance between the pleura and placed hook wire was significantly shorter than the estimated distance between the pleura and hook wire using the conventional route (mean 16.3 vs. 40.9 mm; P = 0.0002). Grade 1 adverse events occurred (11 pneumothoraxes and 4 pulmonary hemorrhages). No grade 2 or higher adverse event was observed.ConclusionsThe transfissural route used for preoperative localization before VATS is useful for selected patients because this route may allow for more limited lung parenchyma resection.« less

21 CFR 870.3670 - Pacemaker charger.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Pacemaker charger. 870.3670 Section 870.3670 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3670 Pacemaker charger. (a...

Modulation of Pacemaker Potentials in Murine Small Intestinal Interstitial Cells of Cajal by Gamisoyo-San, a Traditional Chinese Herbal Medicine.

PubMed

Kim, Doeun; Kim, Jung Nam; Nam, Joo Hyun; Lee, Jong Rok; Kim, Sang Chan; Kim, Byung Joo

2018-04-19

The Gamisoyo-san (GSS) has been used for -improving the gastrointestinal (GI) symptoms. The purpose of this study was to investigate the effects of GSS, a traditional Chinese herbal medicine, on the pacemaker potentials of mouse small intestinal interstitial cells of Cajal (ICCs). ICCs from the small intestines were dissociated and cultured. Whole-cell patch-clamp configuration was used to record pacemaker potentials and membrane currents. GSS depolarized ICC pacemaker potentials in a dose-dependent manner. Pretreatment with 4-diphenylacetoxypiperidinium iodide completely inhibited GSS-induced pacemaker potential depolarizations. Intracellular GDP-β-S inhibited GSS-induced effects, and in the presence of U-73122, GSS-induced effects were inhibited. Also, GSS in the presence of a Ca2+-free solution or thapsigargin did not depolarize pacemaker potentials. However, in the presence of calphostin C, GSS slightly depolarized pacemaker potentials. Furthermore, GSS inhibited both transient receptor potential melastatin7 and Ca2+-activated Cl- channel (anoctamin1) currents. GSS depolarized pacemaker potentials of ICCs via G protein and muscarinic M3 receptor signaling pathways and through internal or external Ca2+-, phospholipase C-, and protein kinase C-dependent and transient receptor potential melastatin 7-, and anoctamin 1-independent pathways. The study shows that GSS may regulate GI tract motility, suggesting that GSS could be a basis for developing novel prokinetic agents for treating GI motility dysfunctions. © 2018 S. Karger AG, Basel.

Successful management of multiple permanent pacemaker complications – infection, 13 year old silent lead perforation and exteriorisation following failed percutaneous extraction, superior vena cava obstruction, tricuspid valve endocarditis, pulmonary embolism and prosthetic tricuspid valve thrombosis

PubMed Central

Kaul, Pankaj; Adluri, Krishna; Javangula, Kalyana; Baig, Wasir

2009-01-01

A 59 year old man underwent mechanical tricuspid valve replacement and removal of pacemaker generator along with 4 pacemaker leads for pacemaker endocarditis and superior vena cava obstruction after an earlier percutaneous extraction had to be abandoned, 13 years ago, due to cardiac arrest, accompanied by silent, unsuspected right atrial perforation and exteriorisation of lead. Postoperative course was complicated by tricuspid valve thrombosis and secondary pulmonary embolism requiring TPA thrombolysis which was instantly successful. A review of literature of pacemaker endocarditis and tricuspid thrombosis along with the relevant management strategies is presented. We believe this case report is unusual on account of non operative management of right atrial lead perforation following an unsuccessful attempt at percutaneous removal of right sided infected pacemaker leads and the incidental discovery of the perforated lead 13 years later at sternotomy, presentation of pacemaker endocarditis with a massive load of vegetations along the entire pacemaker lead tract in superior vena cava, right atrial endocardium, tricuspid valve and right ventricular endocardium, leading to a functional and structural SVC obstruction, requirement of an unusually large dose of warfarin postoperatively occasioned, in all probability, by antibiotic drug interactions, presentation of tricuspid prosthetic valve thrombosis uniquely as vasovagal syncope and isolated hypoxia and near instantaneous resolution of tricuspid prosthetic valve thrombosis with Alteplase thrombolysis. PMID:19239701

Tricuspid valve repair for severe tricuspid regurgitation due to pacemaker leads.

PubMed

Uehara, Kyokun; Minakata, Kenji; Watanabe, Kentaro; Sakaguchi, Hisashi; Yamazaki, Kazuhiro; Ikeda, Tadashi; Sakata, Ryuzo

2016-07-01

Tricuspid valve regurgitation due to pacemaker leads is a well-known complication. Although some reports have suggested that pacemaker leads should be surgically explanted, strongly adhered leads cannot always be removed. The aim of this study was to describe our tricuspid valve repair techniques with pacemaker leads left in situ. Our retrospective study investigated 6 consecutive patients who required tricuspid valve surgery for severe regurgitation induced by pacemaker leads. From the operative findings, we identified 3 patterns of tricuspid valve and pacemaker lead involvement. In 3 patients, the leads were caught in the chordae, in 2 patients, tricuspid regurgitation was caused by lead impingement on the septal leaflet, and in 3 patients, tricuspid valve leaflets had been perforated by the pacemaker leads. During surgery, all leads were left in situ after being separated from the leaflet or valvular apparatus. In addition, suture annuloplasty was performed for annular dilatation in all cases. In one patient, the lead was reaffixed to the annulus after the posterior leaflet was cut back towards the annulus, and the leaflet was then closed. There was one hospital death due to sepsis. The degree of tricuspid regurgitation was trivial in all surviving patients at discharge. During a mean follow-up of 21 months, one patient died from pneumonia 20 months after tricuspid valve repair. In patients undergoing tricuspid valve surgery due to severe tricuspid regurgitation caused by pacemaker leads, the leads can be left in situ after proper repair with annuloplasty. © The Author(s) 2016.

Outcome and management of pacemaker-induced superior vena cava syndrome.

PubMed

Fu, Hai-Xia; Huang, Xin-Miao; Zhong, Li; Osborn, Michael J; Bjarnason, Haraldur; Mulpuru, Siva; Zhao, Xian-Xian; Friedman, Paul A; Cha, Yong-Mei

2014-11-01

We aimed to determine the long-term outcomes of percutaneous lead extraction and stent placement in patients with pacemaker-induced superior vena cava (SVC) syndrome. The study retrospectively screened patients who underwent lead extraction followed by central vein stent implantation at Mayo Clinic (Rochester, MN, USA), from January 2005 to December 2012, to identify the patients with pacemaker-induced SVC syndrome. Demographic, clinical, and follow-up characteristics of those patients were collected from electronic medical records. Six cases were identified. The mean (standard deviation) age was 56 (15) years (male, 67%). All patients had permanent dual-chamber pacemakers, with a mean 11-year history of pacemaker placement. The entire device system was explanted in five patients; one patient had a 21-year-old pacemaker lead that could not be removed. Eight stents were implanted in six patients: five patients had one stent, one patient had three. A new pacemaker system was reimplanted through the stented vein in five patients. Technical success was achieved in all patients, without any complication. Symptoms rapidly resolved in all patients after stent deployment. The mean follow-up duration was 48 months (range, 10-100 months). Three patients remained symptom free. Reintervention with percutaneous balloon venoplasty was successful in three patients with symptom recurrence. Percutaneous stent implantation after lead removal followed by reimplantation of leads is a feasible alternative therapy for pacemaker-induced SVC syndrome, although some cases may require repeat intervention. ©2014 Wiley Periodicals, Inc.

Comparative Study of Electrical Stimulation of the Heart with VDD and DDD Pacemakers as to the Evolution to Atrial Fibrillation

PubMed Central

de Campos, Nelson Leonardo Kerdahi Leite; de Andrade, Rubens Ramos; Fellicio, Marcello Laneza; Martins, Antônio Sergio; Garzesi, André Monti; Garcia, Leonardo Rufino; Takeda, Tassya Bueno

2017-01-01

Introduction The pacemaker implantation VDD is considered simpler, faster, less expensive and causes fewer complications compared to DDD. However, the VDD pacemaker has not been widely used in many centers, perhaps for fear of dysfunction of the sinus node and the reduction of atrial sensitivity by the pacemaker during follow-up after implantation. Objective To compare patients with DDD and VDD pacemakers regarding the evolution of chronic atrial fibrillation (AF) and length of stay outside this postoperative arrhythmia. Methods It was included 158 patients with dual chamber pacemakers, 48 DDD and 110 VDD. Follow-up period: between January 1, 1999 and December 31, 2015. The mean follow-up of patients with DDD was 5.35 years and the VDD, 4.74 years. The percentage of each group (DDD and VDD) which evolved to AF during follow-up was assessed. Also, it was made an actuarial study with the respective curves indicating the time free from AF for each group. Patients were classified according to the diagnosis that led to pacemaker implantation and the degree of heart failure. Results The percentage of patients who developed AF was higher in DDD group (10.42%) than in VDD group (6.36%), but without statistical significance. Patients with DDD and VDD remained free of AF for similar period. Conclusion Considering the results, the VDD pacemaker continues to be a good option to the DDD for routine use in cases properly indicated. PMID:29211212

Comparative Study of Electrical Stimulation of the Heart with VDD and DDD Pacemakers as to the Evolution to Atrial Fibrillation.

PubMed

Campos, Nelson Leonardo Kerdahi Leite de; Andrade, Rubens Ramos de; Fellicio, Marcello Laneza; Martins, Antônio Sergio; Garzesi, André Monti; Garcia, Leonardo Rufino; Takeda, Tassya Bueno

2017-01-01

The pacemaker implantation VDD is considered simpler, faster, less expensive and causes fewer complications compared to DDD. However, the VDD pacemaker has not been widely used in many centers, perhaps for fear of dysfunction of the sinus node and the reduction of atrial sensitivity by the pacemaker during follow-up after implantation. To compare patients with DDD and VDD pacemakers regarding the evolution of chronic atrial fibrillation (AF) and length of stay outside this postoperative arrhythmia. It was included 158 patients with dual chamber pacemakers, 48 DDD and 110 VDD. Follow-up period: between January 1, 1999 and December 31, 2015. The mean follow-up of patients with DDD was 5.35 years and the VDD, 4.74 years. The percentage of each group (DDD and VDD) which evolved to AF during follow-up was assessed. Also, it was made an actuarial study with the respective curves indicating the time free from AF for each group. Patients were classified according to the diagnosis that led to pacemaker implantation and the degree of heart failure. The percentage of patients who developed AF was higher in DDD group (10.42%) than in VDD group (6.36%), but without statistical significance. Patients with DDD and VDD remained free of AF for similar period. Considering the results, the VDD pacemaker continues to be a good option to the DDD for routine use in cases properly indicated.

Evaluation of Death among the Patients Undergoing Permanent Pacemaker Implantation: A Competing Risks Analysis.

PubMed

Ghaem, Haleh; Ghorbani, Mohammad; Zare Dorniani, Samira

2017-06-01

Permanent artificial pacemaker is one of the important therapies for treatment of cardiac conduction system problems. The present study aimed to determine the association between some predictive variables and all-cause and cause-specific mortality in the patients who had undergone pacemaker implantation. This study was conducted on 1207 patients who had undergone permanent pacemaker implantation in the hospitals affiliated with Shiraz University of Medical Sciences, Iran, from Mar 2002 to Mar 2012. The variables that existed in the patients' medical records included sex, diabetes mellitus, obesity, cerebrovascular accident, cardiomegaly, smoking, hypertension, ischemic heart disease, congenital heart disease, sick sinus syndrome, and atrial fibrillation. Competing risks model was used to assess the association between the predictive variables and cause-specific (i.e., cardiac and vascular) mortality. The patients' mean age was 66.32±17.92 yr (70.62±14.45 yr in the patients with single-chamber pacemakers vs. 61.91±17.69 yr in those with two-chamber pacemakers) ( P <0.001). Sick sinus syndrome and age increased the risk of all-cause mortality, while two-chamber pacemaker decreased this risk. Obesity increased the risk of cardiac death, and diabetes mellitus and heart valve disease increased the risk of vascular death. The variables predicting mortality in all-cause model were completely different from those in cause-specific model. Moreover, death in such patients may occur due to reasons other than pacemaker. Therefore, future studies, particularly prospective ones, are recommended to use competing risks models.

Neuropeptide Secreted from a Pacemaker Activates Neurons to Control a Rhythmic Behavior

PubMed Central

Wang, Han; Girskis, Kelly; Janssen, Tom; Chan, Jason P.; Dasgupta, Krishnakali; Knowles, James A.; Schoofs, Liliane; Sieburth, Derek

2013-01-01

Summary Background Rhythmic behaviors are driven by endogenous biological clocks in pacemakers, which must reliably transmit timing information to target tissues that execute rhythmic outputs. During the defecation motor program in C. elegans, calcium oscillations in the pacemaker (intestine), which occur about every 50 seconds, trigger rhythmic enteric muscle contractions through downstream GABAergic neurons that innervate enteric muscles. However, the identity of the timing signal released by the pacemaker and the mechanism underlying the delivery of timing information to the GABAergic neurons are unknown. Results Here we show that a neuropeptide-like protein (NLP-40) released by the pacemaker triggers a single rapid calcium transient in the GABAergic neurons during each defecation cycle. We find that mutants lacking nlp-40 have normal pacemaker function, but lack enteric muscle contractions. NLP-40 undergoes calcium-dependent release that is mediated by the calcium sensor, SNT-2/synaptotagmin. We identify AEX-2, the G protein-coupled receptor on the GABAergic neurons, as the receptor of NLP-40. Functional calcium imaging reveals that NLP-40 and AEX-2/GPCR are both necessary for rhythmic activation of these neurons. Furthermore, acute application of synthetic NLP-40-derived peptide depolarizes the GABAergic neurons in vivo. Conclusions Our results show that NLP-40 carries the timing information from the pacemaker via calcium-dependent release and delivers it to the GABAergic neurons by instructing their activation. Thus, we propose that rhythmic release of neuropeptides can deliver temporal information from pacemakers to downstream neurons to execute rhythmic behaviors. PMID:23583549

A Novel Way Of Repair Of Insulation Breaks During Pacemaker Generator Replacement

PubMed Central

Manzoor Ali, Syed; Iqbal, Khurshid; Tramboo, Nisar A; Lone, Aijaz A; Kaul, Suresh; Kaul, Neelam; Hafiz, Imran

2009-01-01

Minor abrasions can occur while mobilising old lead during pacemaker generator replacement necesittating placement of additional lead adding to the financial burden and junk in heart. We describe a novel way of repair of old pacemaker lead preventing additional lead placement. PMID:19763196

21 CFR 870.3620 - Pacemaker lead adaptor.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Pacemaker lead adaptor. 870.3620 Section 870.3620 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3620 Pacemaker lead adaptor...

21 CFR 870.3650 - Pacemaker polymeric mesh bag.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Pacemaker polymeric mesh bag. 870.3650 Section 870.3650 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3650 Pacemaker polymeric...

21 CFR 870.3630 - Pacemaker generator function analyzer.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Pacemaker generator function analyzer. 870.3630 Section 870.3630 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3630 Pacemaker...

21 CFR 870.3690 - Pacemaker test magnet.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Pacemaker test magnet. 870.3690 Section 870.3690 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3690 Pacemaker test magnet...

21 CFR 870.3720 - Pacemaker electrode function tester.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Pacemaker electrode function tester. 870.3720... electrode function tester. (a) Identification. A pacemaker electrode function tester is a device which is... measuring the patient's pacing threshold and intracardiac R-wave potential. (b) Classification. Class II...

A conserved domain in the NH2 terminus important for assembly and functional expression of pacemaker channels.

PubMed

Tran, Neil; Proenza, Catherine; Macri, Vincenzo; Petigara, Fiona; Sloan, Erin; Samler, Shannon; Accili, Eric A

2002-11-15

Pacemaker channels are formed by co-assembly of hyperpolarization-activated cyclic nucleotide-gated (HCN) subunits. Previously, we suggested that the NH(2) termini of the mouse HCN2 isoform were important for subunit co-assembly and functional channel expression. Using an alignment strategy together with yeast two-hybrid assays, patch clamp electrophysiology, and confocal imaging, we have now identified a domain within the NH(2) terminus of the HCN2 subunit that is responsible for interactions between NH(2) termini and promoting the trafficking of functional channels to the plasma membrane. This domain is composed of 52 amino acids, is located adjacent to the putative first transmembrane segment, and is highly conserved among the mammalian HCN isoforms. This conserved domain, but not the remaining unconserved NH(2)-terminal regions of HCN2, specifically interacted with itself in yeast two-hybrid assays. Moreover, the conserved domain was important for expression of currents. Whereas relatively normal whole cell HCN2 currents were produced by channels containing only the conserved domain, further deletion of this region, leaving only a more polar and putative coiled-coil segment, eliminated HCN2 currents and resulted in proteins that localized predominantly in perinuclear compartments. Thus, we suggest that this conserved domain is the critical NH(2)-terminal determinant of subunit co-assembly and trafficking of pacemaker channels.

76 FR 64228 - Draft Guidance for Industry and Food and Drug Administration Staff; Class II Special Controls...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-17

...: External Pacemaker Pulse Generator; Availability AGENCY: Food and Drug Administration, HHS. ACTION: Notice... entitled ``Class II Special Controls Guidance Document: External Pacemaker Pulse Generator.'' This draft guidance document describes a means by which external pacemaker pulse generators may comply with the...

Two hearts synchronized each other with a DDD pacemaker.

PubMed

Brunacci, Michele; Valbusa, Alberto; Brunelli, Claudio; Bertero, Giovanni

2016-12-01

: We describe the case of a patient with dyspnea and heterotopic cardiac transplant, ventricular fibrillation from the native heart and sinus rhythm from the transplanted one. The two hearts were synchronized with a pacemaker. Electric external cardioversion and a different type of pacemaker stimulation were successfully performed, with improving symptoms.

21 CFR 870.3710 - Pacemaker repair or replacement material.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Pacemaker repair or replacement material. 870.3710 Section 870.3710 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3710 Pacemaker...

Pacemaker failure associated with therapeutic radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brooks, C.; Mutter, M.

1988-11-01

A 48-year-old white man with a multiprogrammable Intramedics 259-01 pacemaker was treated for inoperable lung cancer with a course of cobalt-60 radiotherapy (total 3500 rad). Several weeks subsequent to his last radiation treatment, the patient presented to the emergency department with chest and abdominal pain, shortness of breath, hypotension, and tachycardia. A paced tachycardia was noted, and application of a magnet over the pacemaker completely inhibited its function, allowing a normal sinus rhythm to ensue and the patient's symptoms to be relieved. Pacemaker failure probably was a complication of radiotherapy.

The challenge of staphylococcal pacemaker endocarditis in a patient with transposition of the great arteries endocarditis in congenital heart disease

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ch'ng, Julie; Chan, William; Lee, Paul

2003-06-01

Staphylococcus aureus is a leading cause of septicaemia and infective endocarditis. The overall incidence of staphylococcal bacteraemia is increasing, contributing to 16% of all hospital-acquired bacteraemias. The use of cardiac pacemakers has revolutionized the management of rhythm disturbances, yet this has also resulted in a group of patients at risk of pacemaker lead endocarditis and seeding in the range of 1% to 7%. We describe a 26-year-old man with transposition of the great arteries who had a pacemaker implanted and presented with S. aureus septicaemia 2 years postpacemaker implantation and went on to develop pacemaker lead endocarditis. This report illustratesmore » the risk of endocarditis in the population with congenital heart disease and an intracardiac device.« less

Mathematical Models of Cardiac Pacemaking Function

NASA Astrophysics Data System (ADS)

Li, Pan; Lines, Glenn T.; Maleckar, Mary M.; Tveito, Aslak

2013-10-01

Over the past half century, there has been intense and fruitful interaction between experimental and computational investigations of cardiac function. This interaction has, for example, led to deep understanding of cardiac excitation-contraction coupling; how it works, as well as how it fails. However, many lines of inquiry remain unresolved, among them the initiation of each heartbeat. The sinoatrial node, a cluster of specialized pacemaking cells in the right atrium of the heart, spontaneously generates an electro-chemical wave that spreads through the atria and through the cardiac conduction system to the ventricles, initiating the contraction of cardiac muscle essential for pumping blood to the body. Despite the fundamental importance of this primary pacemaker, this process is still not fully understood, and ionic mechanisms underlying cardiac pacemaking function are currently under heated debate. Several mathematical models of sinoatrial node cell membrane electrophysiology have been constructed as based on different experimental data sets and hypotheses. As could be expected, these differing models offer diverse predictions about cardiac pacemaking activities. This paper aims to present the current state of debate over the origins of the pacemaking function of the sinoatrial node. Here, we will specifically review the state-of-the-art of cardiac pacemaker modeling, with a special emphasis on current discrepancies, limitations, and future challenges.

Dual-chamber pacemakers for treating symptomatic bradycardia due to sick sinus syndrome without atrioventricular block: a systematic review and economic evaluation.

PubMed

Edwards, Steven J; Karner, Charlotta; Trevor, Nicola; Wakefield, Victoria; Salih, Fatima

2015-08-01

Bradycardia [resting heart rate below 60 beats per minute (b.p.m.)] can be caused by conditions affecting the natural pacemakers of the heart, such as sick sinus syndrome (SSS) and atrioventricular (AV) blocks. People suffering from bradycardia may present with palpitations, exercise intolerance and fainting. The only effective treatment for patients suffering from symptomatic bradycardia is implantation of a permanent pacemaker. To appraise the clinical effectiveness and cost-effectiveness of dual-chamber pacemakers compared with single-chamber atrial pacemakers for treating symptomatic bradycardia in people with SSS and no evidence of AV block. All databases (MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Health Technology Assessment database, NHS Economic Evaluations Database) were searched from inception to June 2014. A systematic review of the clinical and economic literature was carried out in accordance with the general principles published by the Centre for Reviews and Dissemination. Randomised controlled trials (RCTs) evaluating dual-chamber and single-chamber atrial pacemakers and economic evaluations were included. Pairwise meta-analysis was carried out. A de novo economic model was developed. Of 493 references, six RCTs were included in the review. The results were predominantly influenced by the largest trial DANPACE. Dual-chamber pacing was associated with a statistically significant reduction in reoperation [odds ratio (OR) 0.48, 95% confidence interval (CI) 0.36 to 0.63] compared with single-chamber atrial pacing. The difference is primarily because of the development of AV block requiring upgrade to a dual-chamber device. The risk of paroxysmal atrial fibrillation was also reduced with dual-chamber pacing compared with single-chamber atrial pacing (OR 0.75, 95% CI 0.59 to 0.96). No statistically significant difference was found between the pacing modes for mortality, heart failure, stroke, chronic atrial fibrillation or quality of life. However, the risk of developing heart failure may vary with age and device. The de novo economic model shows that dual-chamber pacemakers are more expensive and more effective than single-chamber atrial devices, resulting in a base-case incremental cost-effectiveness ratio (ICER) of £6506. The ICER remains below £20,000 in probabilistic sensitivity analysis, structural sensitivity analysis and most scenario analyses and one-way sensitivity analyses. The risk of heart failure may have an impact on the decision to use dual-chamber or single-chamber atrial pacemakers. Results from an analysis based on age (> 75 years or ≤ 75 years) and risk of heart failure indicate that dual-chamber pacemakers dominate single-chamber atrial pacemakers (i.e. are less expensive and more effective) in older patients, whereas dual-chamber pacemakers are dominated by (i.e. more expensive and less effective) single-chamber atrial pacemakers in younger patients. However, these results are based on a subgroup analysis and should be treated with caution. In patients with SSS without evidence of impaired AV conduction, dual-chamber pacemakers appear to be cost-effective compared with single-chamber atrial pacemakers. The risk of developing a complete AV block and the lack of tools to identify patients at high risk of developing the condition argue for the implantation of a dual-chamber pacemaker programmed to minimise unnecessary ventricular pacing. However, considerations have to be made around the risk of developing heart failure, which may depend on age and device. This study is registered as PROSPERO CRD42013006708. The National Institute for Health Research Health Technology Assessment programme.

Magnetization mechanisms in ordered arrays of polycrystalline Fe100-xCox nanowires

NASA Astrophysics Data System (ADS)

Viqueira, M. S.; Bajales, N.; Urreta, S. E.; Bercoff, P. G.

2015-05-01

Magnetization reversal processes and coercivity mechanisms in polycrystalline Fe100-xCox nanowire arrays, resulting from an AC electrodeposition process, are investigated. The array coercivity is described on the basis of polarization reversal mechanisms operating in individual wires, under the effect of inter-wire dipolar interactions described by a mean field approximation. For individual wires, a reversal mechanism involving the nucleation and further expansion of domain-wall like spin configuration is considered. The wires have a mean grain size larger than both the nanowire diameter and the exchange length, so localized and non-cooperative nucleation modes are considered. As the Co content increases, the alloy saturation polarization gradually decreases, but the coercive field and the relative remanence of the arrays increase, indicating that they are not controlled by the shape anisotropy in all the composition range. The coercive field dependence on the angle between the applied field and the wire long axis is not well described by reversal mechanisms involving nucleation and further displacement of neither vortex nor transverse ideal domain walls. On the contrary, the angular dependence of the coercive field observed at room temperature is well predicted by a model considering nucleation of inverse domains by localized curling, in regions smaller than the grain size, exhibiting quite small aspect ratios as compared to those of the entire nanowire. In arrays with higher Co contents, a transition from an initial (small angle) localized curling nucleation mechanism to another one, involving localized coherent rotation is observed at about π/4.

Retrospective analysis of reasons for failure of DDD pacemaker implantation in patients operated on between 1993 and 2005.

PubMed

Lelakowski, Jacek; Majewski, Jacek; Małecka, Barbara; Bednarek, Jacek; Stypuła, Paweł; Szeglowski, Marcin

2007-01-01

During implantation of a DDD pacemaker the following difficulties may be encountered: venous anomalies (the absence of vessels of adequate calibre or difficulty in subclavian vein puncture), arrhythmias during implantation (episodes of atrial flutter/fibrillation while the atrial leads are being positioned), lack of mechanical stability of the electrode in the heart chamber and inability to achieve an acceptable pacing and sensing threshold during implantation. The purpose of the study was to analyse retrospectively the reasons for DDD pacemaker failure in patients operated on between 1993 and 2005. We reviewed retrospectively all implantation data from 1988 to 2005 to identify patients with primary failure of DDD pacemaker implantation. Further analysis included patients who had received a DDD pacemaker between 1993 and 2005, when this type of pacemaker made up between 9 and 40% of all pacemaker implantations. We implanted 7469 pacemakers, including 1958 (26.2%) dual-chamber pacemakers, in 783 patients with atrioventricular block (AVB), 392 with sick sinus syndrome (SSS), 450 with AVB +/- SSS and 333 with tachy-brady syndrome (TBS). The mean age of the patients was 65.5 +/- 17.3 years. DDD pacing was unsuccessful in 108 (1.4%) patients, including 32 with AVB, 22 with SSS, 16 with SSS +/- AVB and 38 with TBS. The mean age of these patients was 78.5 +/- 19.4 years. The reasons for failed implantation were venous anomalies in 12%, an arrhythmia episode in 27.8%, a high pacing threshold in the atrium in 17.6%, low atrial potential amplitude in 25.9% and lack of mechanical stability of the electrode in 16.7% of patients. The difficulties were encountered in elderly patients (p < 0.01), most frequently in patients with SSS and TBS (71). Between 2004 and 2005 venous anomalies and a high pacing threshold were the main causes of failure. Currently the main difficulties encountered during pacemaker implantation are venous anomalies and a high pacing threshold. Arrhythmia episodes, low atrial potential amplitude and lack of mechanical stability are of minor importance. Elderly patients with sick sinus syndrome and tachy-brady syndrome have the highest failure rate. (Cardiol J 2007; 14: 155-159).

Pharmacological characterization of ionic currents that regulate high-frequency spontaneous activity of electromotor neurons in the weakly electric fish, Apteronotus leptorhynchus.

PubMed

Smith, G Troy

2006-01-01

The neural circuit that controls the electric organ discharge (EOD) of the brown ghost knifefish (Apteronotus leptorhynchus) contains two spontaneous oscillators. Both pacemaker neurons in the medulla and electromotor neurons (EMNs) in the spinal cord fire spontaneously at frequencies of 500-1,000 Hz to control the EOD. These neurons continue to fire in vitro at frequencies that are highly correlated with in vivo EOD frequency. Previous studies used channel blocking drugs to pharmacologically characterize ionic currents that control high-frequency firing in pacemaker neurons. The goal of the present study was to use similar techniques to investigate ionic currents in EMNs, the other type of spontaneously active neuron in the electromotor circuit. As in pacemaker neurons, high-frequency firing of EMNs was regulated primarily by tetrodotoxin-sensitive sodium currents and by potassium currents that were sensitive to 4-aminopyridine and kappaA-conotoxin SIVA, but resistant to tetraethylammonium. EMNs, however, differed from pacemaker neurons in their sensitivity to some channel blocking drugs. Alpha-dendrotoxin, which blocks a subset of Kv1 potassium channels, increased firing rates in EMNs, but not pacemaker neurons; and the sodium channel blocker muO-conotoxin MrVIA, which reduced firing rates of pacemaker neurons, had no effect on EMNs. These results suggest that similar, but not identical, ionic currents regulate high-frequency firing in EMNs and pacemaker neurons. The differences in the ionic currents expressed in pacemaker neurons and EMNs might be related to differences in the morphology, connectivity, or function of these two cell types.

Neuropeptide secreted from a pacemaker activates neurons to control a rhythmic behavior.

PubMed

Wang, Han; Girskis, Kelly; Janssen, Tom; Chan, Jason P; Dasgupta, Krishnakali; Knowles, James A; Schoofs, Liliane; Sieburth, Derek

2013-05-06

Rhythmic behaviors are driven by endogenous biological clocks in pacemakers, which must reliably transmit timing information to target tissues that execute rhythmic outputs. During the defecation motor program in C. elegans, calcium oscillations in the pacemaker (intestine), which occur about every 50 s, trigger rhythmic enteric muscle contractions through downstream GABAergic neurons that innervate enteric muscles. However, the identity of the timing signal released by the pacemaker and the mechanism underlying the delivery of timing information to the GABAergic neurons are unknown. Here, we show that a neuropeptide-like protein (NLP-40) released by the pacemaker triggers a single rapid calcium transient in the GABAergic neurons during each defecation cycle. We find that mutants lacking nlp-40 have normal pacemaker function, but lack enteric muscle contractions. NLP-40 undergoes calcium-dependent release that is mediated by the calcium sensor, SNT-2/synaptotagmin. We identify AEX-2, the G-protein-coupled receptor on the GABAergic neurons, as the receptor for NLP-40. Functional calcium imaging reveals that NLP-40 and AEX-2/GPCR are both necessary for rhythmic activation of these neurons. Furthermore, acute application of synthetic NLP-40-derived peptide depolarizes the GABAergic neurons in vivo. Our results show that NLP-40 carries the timing information from the pacemaker via calcium-dependent release and delivers it to the GABAergic neurons by instructing their activation. Thus, we propose that rhythmic release of neuropeptides can deliver temporal information from pacemakers to downstream neurons to execute rhythmic behaviors. Copyright © 2013 Elsevier Ltd. All rights reserved.

Leadless Cardiac Pacemaker Implantation After Lead Extraction in Patients With Severe Device Infection.

PubMed

Kypta, Alexander; Blessberger, Hermann; Kammler, Juergen; Lambert, Thomas; Lichtenauer, Michael; Brandstaetter, Walter; Gabriel, Michael; Steinwender, Clemens

2016-09-01

Conventional pacemaker therapy is limited by short- and long-term complications, most notably device infection. Transcatheter pacing systems (TPS) may be beneficial in this kind of patients as they eliminate the need for a device pocket and leads and thus may reduce the risk of re-infection. We assessed a novel procedure in 6 patients with severe device infection who were pacemaker dependent. After lead extraction a single chamber TPS was implanted into the right ventricle. Of the 6 patients who underwent lead extraction due to severe device infection at our institution, 3 were diagnosed with a pocket infection only, whereas the other 3 showed symptoms of both pocket and lead infection. Successful lead extraction and TPS implantation was accomplished in all patients. Four patients were bridged with a temporary pacemaker between 2 hours and 2 days after lead extraction, whereas 2 patients had the TPS implanted during the same procedure just before traditional pacemaker system removal. All patients stayed free of infection during the follow-up period of 12 weeks. An additional positron emission tomography scan was performed in each patient and indicated no signs of an infection around the TPS. Transcather pacemaker implantation was safe and feasible in 6 patients and did not result in re-infection even if implanted before removal of the infected pacemaker system within the same procedure. Therefore, implantation of a TPS may be an option for patients with severe device infection, especially in those with blocked venous access or who are pacemaker dependent. © 2016 Wiley Periodicals, Inc.

Evaluation of Death among the Patients Undergoing Permanent Pacemaker Implantation: A Competing Risks Analysis

PubMed Central

GHAEM, Haleh; GHORBANI, Mohammad; ZARE DORNIANI, Samira

2017-01-01

Background: Permanent artificial pacemaker is one of the important therapies for treatment of cardiac conduction system problems. The present study aimed to determine the association between some predictive variables and all-cause and cause-specific mortality in the patients who had undergone pacemaker implantation. Methods: This study was conducted on 1207 patients who had undergone permanent pacemaker implantation in the hospitals affiliated with Shiraz University of Medical Sciences, Iran, from Mar 2002 to Mar 2012. The variables that existed in the patients’ medical records included sex, diabetes mellitus, obesity, cerebrovascular accident, cardiomegaly, smoking, hypertension, ischemic heart disease, congenital heart disease, sick sinus syndrome, and atrial fibrillation. Competing risks model was used to assess the association between the predictive variables and cause-specific (i.e., cardiac and vascular) mortality. Results: The patients’ mean age was 66.32±17.92 yr (70.62±14.45 yr in the patients with single-chamber pacemakers vs. 61.91±17.69 yr in those with two-chamber pacemakers) (P<0.001). Sick sinus syndrome and age increased the risk of all-cause mortality, while two-chamber pacemaker decreased this risk. Obesity increased the risk of cardiac death, and diabetes mellitus and heart valve disease increased the risk of vascular death. Conclusion: The variables predicting mortality in all-cause model were completely different from those in cause-specific model. Moreover, death in such patients may occur due to reasons other than pacemaker. Therefore, future studies, particularly prospective ones, are recommended to use competing risks models. PMID:28828325

Characterization of a right atrial subsidiary pacemaker and acceleration of the pacing rate by HCN over-expression.

PubMed

Morris, Gwilym M; D'Souza, Alicia; Dobrzynski, Halina; Lei, Ming; Choudhury, Moinuddin; Billeter, Rudi; Kryukova, Yelena; Robinson, Richard B; Kingston, Paul A; Boyett, Mark R

2013-10-01

Although the right atrium (RA contains subsidiary atrial pacemaker (SAP) tissue that can take over from the sinoatrial node (SAN) in sick sinus syndrome (SSS), SAP tissue is bradycardic. Little is known about SAP tissue and one aim of the study was to characterize ion channel expression to obtain insight into SAP pacemaker mechanisms. A second aim was to determine whether HCN over-expression (a 'biopacemaker'-like strategy) can accelerate the pacemaker rate producing a pacemaker that is similar in nature to the SAN. SAP tissue was isolated from the rat and the leading pacemaker site was characterized. Cell size at the leading pacemaker site in the SAP was smaller than in the RA and comparable to that in the SAN. mRNA levels showed the SAP to be similar to, but distinct from, the SAN. For example, in the SAN and SAP, expression of Tbx3 and HCN1 was higher and Nav1.5 and Cx43 lower than in the RA. Organ-cultured SAP tissue beat spontaneously, but at a slower rate than the SAN. Adenovirus-mediated gene transfer of HCN2 and the chimeric protein HCN212 significantly increased the pacemaker rate of the SAP close to that of the native SAN, but HCN4 was ineffective. SAP tissue near the inferior vena cava is bradycardic, but shares characteristics with the SAN. Pacing can be accelerated by the over-expression of HCN2 or HCN212. This provides proof of concept for the use of SAP tissue as a substrate for biopacemaking in the treatment of SSS.

SU-E-T-585: Optically-Stimulated Luminescent Dosimeters for Monitoring Pacemaker Dose in Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Apicello, L; Riegel, A; Jamshidi, A

2015-06-15

Purpose: A sufficient amount of ionizing radiation can cause failure to components of pacemakers. Studies have shown that permanent damage can occur after a dose of 10 Gy and minor damage to functionality occurs at doses as low as 2 Gy. Optically stimulated thermoluminescent dosimeters (OSLDs) can be used as in vivo dosimeters to predict dose to be deposited throughout the treatment. The purpose of this work is to determine the effectiveness of using OSLDs for in vivo dosimetry of pacemaker dose. Methods: As part of a clinical in vivo dosimetry experience, OSLDs were placed at the site of themore » pacemaker by the therapist for one fraction of the radiation treatment. OSLD measurements were extrapolated to the total dose to be received by the pacemaker during treatment. A total of 79 measurements were collected from November 2011 to December 2013 on six linacs. Sixty-six (66) patients treated in various anatomical sites had the dose of their pacemakers monitored. Results: Of the 79 measurements recorded, 76 measurements (96 %) were below 2 Gy. The mean and standard deviation were 50.12 ± 76.41 cGy. Of the 3 measurements that exceeded 2 Gy, 2 measurements matched the dose predicted in the treatment plan and 1 was repeated after an unexpectedly high Result. The repeated measurement yielded a total dose less than 2 Gy. Conclusion: This analysis suggests OSLDs may be used for in vivo monitoring of pacemaker dose. Further research should be performed to assess the effect of increased backscatter from the pacemaker device.« less

Risk of pacemaker implantation after uneventful successful cavotricuspid isthmus radiofrequency ablation in patients with common atrial flutter.

PubMed

Rodríguez-Mañero, Moisés; González-Melchor, Layla; Ballesteros, Gabriel; Raposeiras-Roubín, Sergio; García-Seara, Javier; López, Xesús Alberte Fernández; Cambeiro, Cristina González; Alcalde, Oscar; García-Bolao, Ignacio; Martínez-Sande, Luis; González-Juanatey, José Ramón

2016-01-01

Little is known about the risk of pacemaker implantation after common atrial flutter ablation in the long-term. We retrospectively reviewed the electrophysiology laboratory database at two Spanish University Hospitals from 1998 to 2012 to identify patients who had undergone successful ablation for cavotricuspid dependent atrial flutter. Cox regression analysis was used to examine the risk of pacemaker implantation. A total of 298 patients were considered eligible for inclusion. The mean age of the enrolled patients was 65.7±11. During 57.7±42.8 months, 30 patients (10.1%) underwent pacemaker implantation. In the stepwise multivariate models only heart rate at the time of the ablation (OR: 0.96; 95% CI: 0.93-0.98; p<0.0001) and intraventricular conduction disturbances in the baseline ECG (OR: 3.87; 95% CI: 1.54-9.70; p=0.004) were independents predictors of the need of pacemaker implantation. A heart rate of ≤65 bpm was identified as the optimal cut-off value to predict the need of pacemaker implantation in the follow-up (sensitivity: 79%, specificity: 74%) by ROC curve analyses. This is the first study of an association between the slow conducting common atrial flutter and subsequent risk of pacemaker implantation. In light of these findings, assessing it prior to ablation can be helpful for the risk stratification of sinus node disease or atrioventricular conduction disease requiring a pacemaker implantation in patients with persistent atrial flutter. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Pacemaker failure resulting from radiation damage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Quertermous, T.; Megahy, M.S.; Das Gupta, D.S.

1983-07-01

The authors present a case of radiation-induced pacemaker failure. After 2000 rad (20 Gy) of photon irradiation for metastatic bronchogenic carcinoma, the pulse generator circuitry failed, producing a runaway rhythm. This suggests that present pacemaker circuitry may be more susceptible to irradiation than previously believed, and that even modest radiation doses can induce life-threatening arrhythmias.

Metallurgical investigation of wire breakage of tyre bead grade.

PubMed

Palit, Piyas; Das, Souvik; Mathur, Jitendra

2015-10-01

Tyre bead grade wire is used for tyre making application. The wire is used as reinforcement inside the polymer of tyre. The wire is available in different size/section such as 1.6-0.80 mm thin Cu coated wire. During tyre making operation at tyre manufacturer company, wire failed frequently. In this present study, different broken/defective wire samples were collected from wire mill for detailed investigation of the defect. The natures of the defects were localized and similar in nature. The fracture surface was of finger nail type. Crow feet like defects including button like surface abnormalities were also observed on the broken wire samples. The defect was studied at different directions under microscope. Different advanced metallographic techniques have been used for detail investigation. The analysis revealed that, white layer of surface martensite was formed and it caused the final breakage of wire. In this present study we have also discussed about the possible reason for the formation of such kind of surface martensite (hard-phase).

Ethics and the cardiac pacemaker: more than just end-of-life issues.

PubMed

Hutchison, Katrina; Sparrow, Robert

2018-05-01

For many years, ethical debate about pacemakers has focused on whether and under what circumstances they may be turned off in end of life care. Several other important ethical issues have been neglected, perhaps because the dilemmas they pose for cardiologists are not so immediate. These include: potential conflicts of interest, particularly those arising from the role of industry employed allied professionals (IEAPs) in pacemaker care; unanticipated impacts of commercial competition and the device improvement cycle; risks associated with remotely accessible software; equity in access to healthcare; and questions about reuse of explanted pacemakers in low and middle income countries. This paper analyses these issues in order to facilitate a more comprehensive approach to ethics and the cardiac pacemaker. Cardiologists should be aware of all of these issues and contribute to ongoing discussions about how they are resolved.

Effect of Applied Potential on Fatigue Life of Electropolished Nitinol Wires

NASA Astrophysics Data System (ADS)

Sivan, Shiril; Di Prima, Matthew; Weaver, Jason D.

2017-09-01

Nitinol is used as a metallic biomaterial in medical devices due to its shape memory and pseudoelastic properties. The clinical performance of nitinol depends on factors which include the surface finish, the local environment, and the mechanical loads to which the device is subjected. Preclinical evaluations of device durability are performed with fatigue tests while electrochemical characterization methods such as ASTM F2129 are employed to evaluate corrosion susceptibility by determining the rest potential and breakdown potential. However, it is well established that the rest potential of a metal surface can vary with the local environment. Very little is known regarding the influence of voltage on fatigue life of nitinol. In this study, we developed a fatigue testing method in which an electrochemical system was integrated with a rotary bend wire fatigue tester. Samples were fatigued at various strain levels at electropotentials anodic and cathodic to the rest potential to determine if it could influence fatigue life. Wires at potentials negative to the rest potential had a significantly higher number of cycles to fracture than wires held at potentials above the breakdown potential. For wires for which no potential was applied, they had fatigue life similar to wires at negative potentials.

Thermocouple assembly

DOEpatents

Thermos, Anthony Constantine; Rahal, Fadi Elias

2002-01-01

A thermocouple assembly includes a thermocouple; a plurality of lead wires extending from the thermocouple; an insulating jacket extending along and enclosing the plurality of leads; and at least one internally sealed area within the insulating jacket to prevent fluid leakage along and within the insulating jacket. The invention also provides a method of preventing leakage of a fluid along and through an insulating jacket of a thermocouple including the steps of a) attaching a plurality of lead wires to a thermocouple; b) adding a heat sensitive pseudo-wire to extend along the plurality of lead wires; c) enclosing the lead wires and pseudo-wire inside an insulating jacket; d) locally heating axially spaced portions of the insulating jacket to a temperature which melts the pseudo-wire and fuses it with an interior surface of the jacket.

The Mechanism of Action of Zingerone in the Pacemaker Potentials of Interstitial Cells of Cajal Isolated from Murine Small Intestine.

PubMed

Kim, Jung Nam; Kim, Hyun Jung; Kim, Iksung; Kim, Yun Tai; Kim, Byung Joo

2018-01-01

Zingerone, a major component found in ginger root, is clinically effective for the treatment of various diseases. Interstitial cells of Cajal (ICCs) are the pacemaker cells responsible for slow waves in the gastrointestinal (GI) tract. We investigated the effects of zingerone on the pacemaker potentials of ICCs to assess its mechanisms of action and its potential as a treatment for GI tract motility disorder. We isolated ICCs from small intestines, and the whole-cell patch-clamp configuration was used to record the pacemaker potentials in cultured ICCs. Under the current clamping mode, zingerone inhibited pacemaker potentials of ICCs concentration-dependently. These effects were blocked not by capsazepine, a transient receptor potential vanilloid 1 (TRPV1) channel blocker, but by glibenclamide, a specific ATP-sensitive K+ channel blocker. Pretreatment with SQ-22536 (an adenylate cyclase inhibitor), LY294002 (a phosphoinositide 3-kinase inhibitor), and calphostin C (a protein kinase C (PKC) inhibitor) did not block the effects of zingerone on the pacemaker potentials relative to treatment with zingerone alone. However, zingerone-induced pacemaker potential inhibition was blocked by 1H-[1,2,4] oxadiazolo [4,3-a] quinoxalin-1-one (ODQ; a guanylate cyclase inhibitor), KT5823 (a protein kinase G (PKG) inhibitor), and L-NAME (a non-selective nitric oxide synthase (NOS) inhibitor). In addition, zingerone stimulated cyclic guanosine monophosphate (cGMP) production in ICCs. Finally, pretreatment with PD98059 (a p42/44 mitogen-activated protein kinase (MAPK) inhibitor), SB203580 (a p38 MAPK inhibitor), and SP600125 (c-Jun N-terminal kinases (JNK)-specific inhibitor) blocked the zingerone-induced pacemaker potential inhibition. These results suggest that zingerone concentration-dependently inhibits pacemaker potentials of ICCs via NO/cGMP-dependent ATP-sensitive K+ channels through MAPK-dependent pathways. Taken together, this study shows that zingerone may have the potential for development as a GI regulation agent. © 2018 The Author(s). Published by S. Karger AG, Basel.

Successful pacing using a batteryless sunlight-powered pacemaker.

PubMed

Haeberlin, Andreas; Zurbuchen, Adrian; Schaerer, Jakob; Wagner, Joerg; Walpen, Sébastien; Huber, Christoph; Haeberlin, Heinrich; Fuhrer, Juerg; Vogel, Rolf

2014-10-01

Today's cardiac pacemakers are powered by batteries with limited energy capacity. As the battery's lifetime ends, the pacemaker needs to be replaced. This surgical re-intervention is costly and bears the risk of complications. Thus, a pacemaker without primary batteries is desirable. The goal of this study was to test whether transcutaneous solar light could power a pacemaker. We used a three-step approach to investigate the feasibility of sunlight-powered cardiac pacing. First, the harvestable power was estimated. Theoretically, a subcutaneously implanted 1 cm(2) solar module may harvest ∼2500 µW from sunlight (3 mm implantation depth). Secondly, ex vivo measurements were performed with solar cells placed under pig skin flaps exposed to a solar simulator and real sunlight. Ex vivo measurements under real sunlight resulted in a median output power of 4941 µW/cm(2) [interquartile range (IQR) 3767-5598 µW/cm(2), median skin flap thickness 3.0 mm (IQR 2.7-3.3 mm)]. The output power strongly depended on implantation depth (ρSpearman = -0.86, P < 0.001). Finally, a batteryless single-chamber pacemaker powered by a 3.24 cm(2) solar module was implanted in vivo in a pig to measure output power and to pace. In vivo measurements showed a median output power of >3500 µW/cm(2) (skin flap thickness 2.8-3.84 mm). Successful batteryless VVI pacing using a subcutaneously implanted solar module was performed. Based on our results, we estimate that a few minutes of direct sunlight (irradiating an implanted solar module) allow powering a pacemaker for 24 h using a suitable energy storage. Thus, powering a pacemaker by sunlight is feasible and may be an alternative energy supply for tomorrow's pacemakers. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

Feasibility and safety of adenosine cardiovascular magnetic resonance in patients with MR conditional pacemaker systems at 1.5 Tesla.

PubMed

Klein-Wiele, Oliver; Garmer, Marietta; Urbien, Rhyan; Busch, Martin; Kara, Kaffer; Mateiescu, Serban; Grönemeyer, Dietrich; Schulte-Hermes, Michael; Garbrecht, Marc; Hailer, Birgit

2015-12-22

Cardiovascular Magnetic Resonance (CMR) with adenosine stress is a valuable diagnostic tool in coronary artery disease (CAD). However, despite the development of MR conditional pacemakers CMR is not yet established in clinical routine for pacemaker patients with known or suspected CAD. A possible reason is that adenosine stress perfusion for ischemia detection in CMR has not been studied in patients with cardiac conduction disease requiring pacemaker therapy. Other than under resting conditions it is unclear whether MR safe pacing modes (paused pacing or asynchronous mode) can be applied safely because the effect of adenosine on heart rate is not precisely known in this entity of patients. We investigate for the first time feasibility and safety of adenosine stress CMR in pacemaker patients in clinical routine and evaluate a pacing protocol that considers heart rate changes under adenosine. We retrospectively analyzed CMR scans of 24 consecutive patients with MR conditional pacemakers (mean age 72.1 ± 11.0 years) who underwent CMR in clinical routine for the evaluation of known or suspected CAD. MR protocol included cine imaging, adenosine stress perfusion and late gadolinium enhancement. Pacemaker indications were sinus node dysfunction (n = 18) and second or third degree AV block (n = 6). Under a pacing protocol intended to avoid competitive pacing on the one hand and bradycardia due to AV block on the other no arrhythmia occurred. Pacemaker stimulation was paused to prevent competitive pacing in sinus node dysfunction with resting heart rate >45 bpm. Sympatho-excitatory effect of adenosine led to a significant acceleration of heart rate by 12.3 ± 8.3 bpm (p < 0.001), no bradycardia occurred. On the contrary in AV block heart rate remained constant; asynchronous pacing above resting heart rate did not interfere with intrinsic rhythm. Adenosine stress CMR appears to be feasible and safe in patients with MR conditional pacemakers. Heart rate response to adenosine has to be considered for the choice of pacing modes during CMR.

SU-E-T-802: Verification of Implanted Cardiac Pacemaker Doses in Intensity-Modulated Radiation Therapy: Dose Prediction Accuracy and Reduction Effect of a Lead Sheet

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, J; Chung, J

2015-06-15

Purpose: To verify delivered doses on the implanted cardiac pacemaker, predicted doses with and without dose reduction method were verified using the MOSFET detectors in terms of beam delivery and dose calculation techniques in intensity-modulated radiation therapy (IMRT). Methods: The pacemaker doses for a patient with a tongue cancer were predicted according to the beam delivery methods [step-and-shoot (SS) and sliding window (SW)], intensity levels for dose optimization, and dose calculation algorithms. Dosimetric effects on the pacemaker were calculated three dose engines: pencil-beam convolution (PBC), analytical anisotropic algorithm (AAA), and Acuros-XB. A lead shield of 2 mm thickness was designedmore » for minimizing irradiated doses to the pacemaker. Dose variations affected by the heterogeneous material properties of the pacemaker and effectiveness of the lead shield were predicted by the Acuros-XB. Dose prediction accuracy and the feasibility of the dose reduction strategy were verified based on the measured skin doses right above the pacemaker using mosfet detectors during the radiation treatment. Results: The Acuros-XB showed underestimated skin doses and overestimated doses by the lead-shield effect, even though the lower dose disagreement was observed. It led to improved dose prediction with higher intensity level of dose optimization in IMRT. The dedicated tertiary lead sheet effectively achieved reduction of pacemaker dose up to 60%. Conclusion: The current SS technique could deliver lower scattered doses than recommendation criteria, however, use of the lead sheet contributed to reduce scattered doses.Thin lead plate can be a useful tertiary shielder and it could not acuse malfunction or electrical damage of the implanted pacemaker in IMRT. It is required to estimate more accurate scattered doses of the patient with medical device to design proper dose reduction strategy.« less

Management and outcome of topical beta-blockerinduced atrioventricular block

PubMed Central

Özcan, Kazım Serhan; Güngör, Barış; Tekkeşin, Ahmet İlker; Altay, Servet; Ekmekçi, Ahmet; Toprak, Ercan; Yıldırım, Ersin; Çalık, Nazmi; Alper, Ahmet Taha; Gürkan, Kadir; Erdinler, İzzet; Osmonov, Damirbek

2015-01-01

Summary Background Topical beta-blockers have a well-established role in the treatment of glaucoma. We aimed to investigate the outcome of patients who developed symptomatic atrioventricular (AV) block induced by topical beta-blockers. Methods All patients admitted or discharged from our institution, the Siyami Ersek Training and Research Hospital, between January 2009 and January 2013 with a diagnosis of AV block were included in the study. Subjects using ophthalmic beta-blockers were recruited and followed for permanent pacemaker requirement during hospitalisation and for three months after discontinuation of the drug. A permanent pacemaker was implanted in patients in whom AV block persisted beyond 72 hours or recurred during the follow-up period. Results A total of 1 122 patients were hospitalised with a diagnosis of AV block and a permanent pacemaker was implanted in 946 cases (84.3%) during the study period. Thirteen patients using ophthalmic beta-blockers for the treatment of glaucoma and no other rate-limiting drugs were included in the study. On electrocardiography, eight patients had complete AV block and five had high-degree AV block. The ophthalmic beta-blockers used were timolol in seven patients (55%), betaxolol in four (30%), and cartelol in two cases (15%). The mean duration of ophthalmic beta-blocker treatment was 30.1 ± 15.9 months. After drug discontinuation, in 10 patients the block persisted and a permanent pacemaker was implanted. During follow up, one more patient required pacemaker implantation. Therefore in total, pacemakers were implanted in 11 out of 13 patients (84.6%). The pacemaker implantation rate did not differ according to the type of topical beta-blocker used (p = 0.37). The presence of infra-nodal block on electrocardiography was associated with higher rates of pacemaker implantation. Conclusion Our results indicate that topical beta-blockers for the treatment of glaucoma may cause severe conduction abnormalities and when AV block occurs, pacemaker implantation is required in a high percentage of the patients. PMID:26659434

Acute pericarditis with cardiac tamponade induced by pacemaker implantation.

PubMed

Shingaki, Masami; Kobayashi, Yutaka; Suzuki, Haruo

2015-11-01

An 87-year-old woman was diagnosed with third-degree atrioventricular block and underwent pacemaker implantation. On postoperative day 12, she experienced cardiac tamponade that was suspected on computed tomography to be caused by lead perforation; therefore, we performed open-heart surgery. However, we could not identify a perforation site on the heart, and drained a 400-mL exudative pericardial effusion. Subsequently, we diagnosed the pericardial effusion as due to pericarditis induced by pacemaker implantation. It is sometimes difficult to distinguish pericarditis from pacemaker lead perforation, so both should be included in the differential diagnosis. © The Author(s) 2014.

[Temporary Pacemakers - Step by Step].

PubMed

Graf, Matthias; Stiller, Patrick; Karch, Martin

2018-06-01

Symptomatic bradycardia is usually caused by abnormalities of atrioventricular conduction or sinus node dysfunction. Reversible and irreversible causes must be considered.Temporary pacemakers are used in the emergency treatment in case of severe bradyarrhythmia.They help to bridge the acute phase until spontaneous restoration of atrioventricular or sinus node function or -if spontaneous restoration fails- until a permanent pacemaker system was implanted.In the following article we discuss the commonly used temporary pacemaker systems. We demonstrate their use and correct programming by an illustrated step by step explanation. For troubleshooting a flow chart was added. © Georg Thieme Verlag KG Stuttgart · New York.

Pacemakers handshake synchronization mechanism of mammalian respiratory rhythmogenesis

PubMed Central

Wittmeier, Steffen; Song, Gang; Duffin, James; Poon, Chi-Sang

2008-01-01

Inspiratory and expiratory rhythms in mammals are thought to be generated by pacemaker-like neurons in 2 discrete brainstem regions: pre-Bötzinger complex (preBötC) and parafacial respiratory group (pFRG). How these putative pacemakers or pacemaker networks may interact to set the overall respiratory rhythm in synchrony remains unclear. Here, we show that a pacemakers 2-way “handshake” process comprising pFRG excitation of the preBötC, followed by reverse inhibition and postinhibitory rebound (PIR) excitation of the pFRG and postinspiratory feedback inhibition of the preBötC, can provide a phase-locked mechanism that sequentially resets and, hence, synchronizes the inspiratory and expiratory rhythms in neonates. The order of this handshake sequence and its progression vary depending on the relative excitabilities of the preBötC vs. the pFRG and resultant modulations of the PIR in various excited and depressed states, leading to complex inspiratory and expiratory phase-resetting behaviors in neonates and adults. This parsimonious model of pacemakers synchronization and mutual entrainment replicates key experimental data in vitro and in vivo that delineate the developmental changes in respiratory rhythm from neonates to maturity, elucidating their underlying mechanisms and suggesting hypotheses for further experimental testing. Such a pacemakers handshake process with conjugate excitation–inhibition and PIR provides a reinforcing and evolutionarily advantageous fail-safe mechanism for respiratory rhythmogenesis in mammals. PMID:19008356

A pacemaker powered by an implantable biofuel cell operating under conditions mimicking the human blood circulatory system--battery not included.

PubMed

Southcott, Mark; MacVittie, Kevin; Halámek, Jan; Halámková, Lenka; Jemison, William D; Lobel, Robert; Katz, Evgeny

2013-05-07

Biocatalytic electrodes made of buckypaper were modified with PQQ-dependent glucose dehydrogenase on the anode and with laccase on the cathode and were assembled in a flow biofuel cell filled with serum solution mimicking the human blood circulatory system. The biofuel cell generated an open circuitry voltage, Voc, of ca. 470 mV and a short circuitry current, Isc, of ca. 5 mA (a current density of 0.83 mA cm(-2)). The power generated by the implantable biofuel cell was used to activate a pacemaker connected to the cell via a charge pump and a DC-DC converter interface circuit to adjust the voltage produced by the biofuel cell to the value required by the pacemaker. The voltage-current dependencies were analyzed for the biofuel cell connected to an Ohmic load and to the electronic loads composed of the interface circuit, or the power converter, and the pacemaker to study their operation. The correct pacemaker operation was confirmed using a medical device - an implantable loop recorder. Sustainable operation of the pacemaker was achieved with the system closely mimicking human physiological conditions using a single biofuel cell. This first demonstration of the pacemaker activated by the physiologically produced electrical energy shows promise for future electronic implantable medical devices powered by electricity harvested from the human body.

Adaptations in Locus Coeruleus Induced by Post-Traumatic Stress Disorder

DTIC Science & Technology

2013-11-01

optogenetics, channelrhodopsin-2, fear conditioning, pacemaking , calcium, synaptic plasticity, corticotropin-releasing factor (CRF), endoplasmic...neurons revealed tonic, pacemaking activity was accompanied by an underlying membrane potential oscillation that was sensitive to the dihydropyridine...prominent, opening of these channels was not necessary to sustain normal pacemaking at rest. However, these channels help support LC spiking during

Delamination of Pearlitic Steel Wires: The Defining Role of Prior-Drawing Microstructure

NASA Astrophysics Data System (ADS)

Durgaprasad, A.; Giri, S.; Lenka, S.; Sarkar, Sudip Kumar; Biswas, Aniruddha; Kundu, S.; Mishra, S.; Chandra, S.; Doherty, R. D.; Samajdar, I.

2018-06-01

This article reports the occasional (< 10 pct of the actual production) delamination of pearlitic wires subjected to a drawing strain of 2.5. The original wire rods which exhibited post-drawing delamination had noticeably lower axial alignment of the pearlite: 22 ± 5 pct vs 34 ± 4 pct in the nondelaminated wires. Although all wires had similar through-thickness texture and stress gradients, delaminated wires had stronger gradients in composition and higher hardness across the ferrite-cementite interface. Carbide dissolution and formation of supersaturated ferrite were clearly correlated with delamination, which could be effectively mitigated by controlled laboratory annealing at 673 K. Direct observations on samples subjected to simple shear revealed significant differences in shear localizations. These were controlled by pearlite morphology and interlamellar spacing. Prior-drawing microstructure of coarse misaligned pearlite thus emerged as a critical factor in the wire drawing-induced delamination of the pearlitic wires.

How smart should pacemakers Be?

PubMed

Saoudi, N; Appl, U; Anselme, F; Voglimacci, M; Cribier, A

1999-03-11

The concept of the "smart" pacemaker has been continuously changing during 40 years of progress in technology. When we talk today about smart pacemakers, it means optimal treatment, diagnosis, and follow-up for patients fitting the current indications for pacemakers. So what is smart today becomes accepted as "state of the art" tomorrow. Originally, implantable pacemakers were developed to save lives from prolonged episodes of bradycardia and/or complete heart block. Now, in addition, they improve quality of life via numerous different functions acting under specific conditions, thanks to the introduction of microprocessors. The devices have become smaller, with the miniaturization of the electrical components, without compromising longevity. Nevertheless, there are still some unmatched objectives for these devices, for example, the optimization of cardiac output and the management of atrial arrhythmias in dual-chamber devices. Furthermore, indications continue to evolve, which in turn require new, additional functions. These functions are often very complex, necessitating computerized programming to simplify application. In addition, the follow-up of these devices is time-consuming, as appropriate system performance has to be regularly monitored. A great many of these functions could be automatically performed and documented, thus enabling physicians and paramedical staff to avoid losing time with routine control procedures. In addition, modern pacemakers offer extensive diagnostic functions to help diagnose patient symptoms and pacemaker system problems. Different types of data are available, and their presentation differs from one company to the other. This huge amount of data can only be managed with automatic diagnostic functions. Thus, the smart pacemaker of the near future should offer high flexibility to permit easy programming of available therapies and follow-up, and extensive, easily comprehensible diagnostic functions.

The Circadian Neuropeptide PDF Signals Preferentially through a Specific Adenylate Cyclase Isoform AC3 in M Pacemakers of Drosophila

PubMed Central

Duvall, Laura B.; Taghert, Paul H.

2012-01-01

The neuropeptide Pigment Dispersing Factor (PDF) is essential for normal circadian function in Drosophila. It synchronizes the phases of M pacemakers, while in E pacemakers it decelerates their cycling and supports their amplitude. The PDF receptor (PDF-R) is present in both M and subsets of E cells. Activation of PDF-R stimulates cAMP increases in vitro and in M cells in vivo. The present study asks: What is the identity of downstream signaling components that are associated with PDF receptor in specific circadian pacemaker neurons? Using live imaging of intact fly brains and transgenic RNAi, we show that adenylate cyclase AC3 underlies PDF signaling in M cells. Genetic disruptions of AC3 specifically disrupt PDF responses: they do not affect other Gs-coupled GPCR signaling in M cells, they can be rescued, and they do not represent developmental alterations. Knockdown of the Drosophila AKAP-like scaffolding protein Nervy also reduces PDF responses. Flies with AC3 alterations show behavioral syndromes consistent with known roles of M pacemakers as mediated by PDF. Surprisingly, disruption of AC3 does not alter PDF responses in E cells—the PDF-R(+) LNd. Within M pacemakers, PDF-R couples preferentially to a single AC, but PDF-R association with a different AC(s) is needed to explain PDF signaling in the E pacemakers. Thus critical pathways of circadian synchronization are mediated by highly specific second messenger components. These findings support a hypothesis that PDF signaling components within target cells are sequestered into “circadian signalosomes,” whose compositions differ between E and M pacemaker cell types. PMID:22679392

The circadian neuropeptide PDF signals preferentially through a specific adenylate cyclase isoform AC3 in M pacemakers of Drosophila.

PubMed

Duvall, Laura B; Taghert, Paul H

2012-01-01

The neuropeptide Pigment Dispersing Factor (PDF) is essential for normal circadian function in Drosophila. It synchronizes the phases of M pacemakers, while in E pacemakers it decelerates their cycling and supports their amplitude. The PDF receptor (PDF-R) is present in both M and subsets of E cells. Activation of PDF-R stimulates cAMP increases in vitro and in M cells in vivo. The present study asks: What is the identity of downstream signaling components that are associated with PDF receptor in specific circadian pacemaker neurons? Using live imaging of intact fly brains and transgenic RNAi, we show that adenylate cyclase AC3 underlies PDF signaling in M cells. Genetic disruptions of AC3 specifically disrupt PDF responses: they do not affect other Gs-coupled GPCR signaling in M cells, they can be rescued, and they do not represent developmental alterations. Knockdown of the Drosophila AKAP-like scaffolding protein Nervy also reduces PDF responses. Flies with AC3 alterations show behavioral syndromes consistent with known roles of M pacemakers as mediated by PDF. Surprisingly, disruption of AC3 does not alter PDF responses in E cells--the PDF-R(+) LNd. Within M pacemakers, PDF-R couples preferentially to a single AC, but PDF-R association with a different AC(s) is needed to explain PDF signaling in the E pacemakers. Thus critical pathways of circadian synchronization are mediated by highly specific second messenger components. These findings support a hypothesis that PDF signaling components within target cells are sequestered into "circadian signalosomes," whose compositions differ between E and M pacemaker cell types.

Enrichment of cardiac pacemaker-like cells: neuregulin-1 and cyclic AMP increase I(f)-current density and connexin 40 mRNA levels in fetal cardiomyocytes.

PubMed

Ruhparwar, Arjang; Er, Fikret; Martin, Ulrich; Radke, Kristin; Gruh, Ina; Niehaus, Michael; Karck, Matthias; Haverich, Axel; Hoppe, Uta C

2007-02-01

Generation of a large number of cells belonging to the cardiac pacemaker system would constitute an important step towards their utilization as a biological cardiac pacemaker system. The aim of the present study was to identify factors, which might induce transformation of a heterogenous population of fetal cardiomyocytes into cells with a pacemaker-like phenotype. Neuregulin-1 (alpha- and beta-isoform) or the cAMP was added to fresh cell cultures of murine embryonic cardiomyocytes. Quantitative northern blot analysis and flowcytometry were performed to detect the expression of connexins 40, 43 and 45. Patch clamp recordings in the whole cell configuration were performed to determine current density of I (f), a characteristic ion current of pacemaker cells. Fetal cardiomyocytes without supplement of neuregulin or cAMP served as control group. Neuregulin and cAMP significantly increased mRNA levels of connexin 40 (Cx-40), a marker of the early differentiating conduction system in mice. On the protein level, flowcytometry revealed no significant differences between treated and untreated groups with regard to the expression of connexins 40, 43 and 45. Treatment with cAMP (11.2 +/- 2.24 pA/pF; P < 0.001) and neuregulin-1-beta (6.23 +/- 1.07 pA/pF; P < 0.001) significantly increased the pacemaker current density compared to control cardiomyocytes (1.76 +/- 0.49 pA/pF). Our results indicate that neuregulin-1 and cAMP possess the capacity to cause significant transformation of a mixed population of fetal cardiomyocytes into cardiac pacemaker-like cells as shown by electrophysiology and increase of Cx-40 mRNA. This method may allow the development of a biological cardiac pacemaker system when applied to adult or embryonic stem cells.

The rationale and design of the Micra Transcatheter Pacing Study: safety and efficacy of a novel miniaturized pacemaker.

PubMed

Ritter, Philippe; Duray, Gabor Z; Zhang, Shu; Narasimhan, Calambur; Soejima, Kyoko; Omar, Razali; Laager, Verla; Stromberg, Kurt; Williams, Eric; Reynolds, Dwight

2015-05-01

Recent advances in miniaturization technologies and battery chemistries have made it possible to develop a pacemaker small enough to implant within the heart while still aiming to provide similar battery longevity to conventional pacemakers. The Micra Transcatheter Pacing System is a miniaturized single-chamber pacemaker system that is delivered via catheter through the femoral vein. The pacemaker is implanted directly inside the right ventricle of the heart, eliminating the need for a device pocket and insertion of a pacing lead, thereby potentially avoiding some of the complications associated with traditional pacing systems. The Micra Transcatheter Pacing Study is currently undergoing evaluation in a prospective, multi-site, single-arm study. Approximately 720 patients will be implanted at up to 70 centres around the world. The study is designed to have a continuously growing body of evidence and data analyses are planned at various time points. The primary safety and efficacy objectives at 6-month post-implant are to demonstrate that (i) the percentage of Micra patients free from major complications related to the Micra system or implant procedure is significantly higher than 83% and (ii) the percentage of Micra patients with both low and stable thresholds is significantly higher than 80%. The safety performance benchmark is based on a reference dataset of 977 subjects from 6 recent pacemaker studies. The Micra Transcatheter Pacing Study will assess the safety and efficacy of a miniaturized, totally endocardial pacemaker in patients with an indication for implantation of a single-chamber ventricular pacemaker. NCT02004873. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

Case study thoracic radiotherapy in an elderly patient with pacemaker: The issue of pacing leads

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kirova, Youlia M., E-mail: youlia.kirova@curie.net; Menard, Jean; Chargari, Cyrus

2012-07-01

To assess clinical outcome of patients with pacemaker treated with thoracic radiation therapy for T8-T9 paravertebral chloroma. A 92-year-old male patient with chloroma presenting as paravertebral painful and compressive (T8-T9) mass was referred for radiotherapy in the Department of Radiation Oncology, Institut Curie. The patient presented with cardiac dysfunction and a permanent pacemaker that had been implanted prior. The decision of Multidisciplinary Meeting was to deliver 30 Gy in 10 fractions for reducing the symptoms and controlling the tumor growth. The patient received a total dose of 30 Gy in 10 fractions using 4-field conformal radiotherapy with 20-MV photons. Themore » dose to pacemaker was 0.1 Gy but a part of the pacing leads was in the irradiation fields. The patient was treated the first time in the presence of his radiation oncologist and an intensive care unit doctor. Moreover, the function of his pacemaker was monitored during the entire radiotherapy course. No change in pacemaker function was observed during any of the radiotherapy fractions. The radiotherapy was very well tolerated without any side effects. The function of the pacemaker was checked before and after the radiotherapy treatment by the cardiologist and no pacemaker dysfunction was observed. Although updated guidelines are needed with acceptable dose criteria for implantable cardiac devices, it is possible to treat patients with these devices and parts encroaching on the radiation field. This case report shows we were able to safely treat our patient through a multidisciplinary approach, monitoring the patient during each step of the treatment.« less

Long-Term Mortality Effect of Early Pacemaker Implantation After Surgical Aortic Valve Replacement.

PubMed

Greason, Kevin L; Lahr, Brian D; Stulak, John M; Cha, Yong-Mei; Rea, Robert F; Schaff, Hartzell V; Dearani, Joseph A

2017-10-01

The need for pacemaker implantation is a well-described complication of aortic valve replacement. Not so well described is the effect such an event has on long-term outcome. This study reviewed a 21-year experience at the Mayo Clinic (Rochester, Minnesota) with aortic valve replacement to understand the influence of early postoperative pacemaker implantation on long-term mortality rates more clearly. This study retrospectively reviewed the records of 5,842 patients without previous pacemaker implantation who underwent surgical aortic valve replacement from January 1993 through June 2014. The median age of these patients was 73 years (range, 65 to 79 years), the median ejection fraction was 62% (range, 53% to 68%), 3,853 patients were male (66%), and coronary artery bypass graft operation was performed in 2,553 (44%) of the patients studied. Early pacemaker implantation occurred in 146 patients (2.5%) within 30 days of surgical aortic valve replacement. The median follow-up of patients was 11.1 years (range, 5.8 to 16.5 years), and all-cause mortality rates were 2.4% at 30 days, 6.4% at 1 year, 23.1% at 5 years, 48.3% at 10 years, and 67.9% at 15 years postoperatively. Early pacemaker implantation was associated with an increased risk of death after multivariable adjustment for baseline patients' characteristics (hazard ratio, 1.49; 95% confidence interval, 1.20, 1.84; p < 0.001). Early pacemaker implantation as a complication of surgical aortic valve replacement is associated with an increased risk of long-term death. Valve replacement-related pacemaker implantation rates should be important considerations with respect to new valve replacement paradigms, especially in younger and lower-risk patients. Copyright © 2017 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Late Outcome and Predictors of Adverse Events Related to the Implantation of a Permanent Pacemaker in Patients with Isolated Congenital Atrioventricular Block.

PubMed

de Oliveira, Grasiele Bess; de Oliveira, Fábio Silveira; Osório, Ana Paula Susin; Medeiros, Alexandre Kreling; Sant'anna, João Ricardo Michielin; Leiria, Tiago Luiz Luz

2016-10-01

Isolated congenital atrioventricular block (ICAVB) is a rare, and pacemaker implantation is the only effective treatment. We sought to identify the predictive factors of adverse events related to pacemaker implantation in ICAVB. This is a cohort study of patients diagnosed with ICAVB who underwent pacemaker implantation from 1980 to 2014 in a single center. During the studied period, a total of 647 patients underwent implantation of their first permanent cardiac pacemaker before 30 years of age. Of these, only 62 (9.5 %) were diagnosed with ICAVB. This condition was diagnosed in utero in 15 (24.2 %) cases, 5 (8.1 %) in the neonatal period, 32 (51.6 %) during childhood, and 10 (16.1 %) during adolescence and young adulthood. The presence of autoantibodies (anti-Ro/SSA) was observed in 41 % of mothers who underwent serological evaluation. Age at the time of the initial pacemaker implant was 9.8 ± 9 years. During a mean follow-up time of 15 years, 1 (1.7 %) death occurred due to infectious endocarditis. Complications related to pacemaker implant were reported in 24 patients (38.7 %). The number of complications was significantly higher in the group with an epimyocardial implantation site (HR 6; CI 2.45-14.95). Ventricular dysfunction occurred in 6 (11.7 %) patients; however, we were not able to identify any predictors of it. Our results showed a low mortality rate after permanent therapy. However, these patients exhibited high morbidity related to the pacemaker system, and the epimyocardial implant site was an independent predictor of complications. Predictors of left ventricular dysfunction were not found in the present study.

Clinical benefits of remote versus transtelephonic monitoring of implanted pacemakers.

PubMed

Crossley, George H; Chen, Jane; Choucair, Wassim; Cohen, Todd J; Gohn, Douglas C; Johnson, W Ben; Kennedy, Eleanor E; Mongeon, Luc R; Serwer, Gerald A; Qiao, Hongyan; Wilkoff, Bruce L

2009-11-24

The purpose of this study was to evaluate remote pacemaker interrogation for the earlier diagnosis of clinically actionable events compared with traditional transtelephonic monitoring and routine in-person evaluation. Pacemaker patient follow-up procedures have evolved from evaluating devices with little programmability and diagnostic information solely in person to transtelephonic rhythm strip recordings that allow monitoring of basic device function. More recently developed remote monitoring technology leverages expanded device capabilities, augmenting traditional transtelephonic monitoring to evaluate patients via full device interrogation. The time to first diagnosis of a clinically actionable event was compared in patients who were followed by remote interrogation (Remote) and those who were followed per standard of care with office visits augmented by transtelephonic monitoring (Control). Patients were randomized 2:1. Remote arm patients transmitted pacemaker information at 3-month intervals. Control arm patients with a single-chamber pacemaker transmitted at 2-month intervals. Control arm patients with dual-chamber devices transmitted at 2-month intervals with an office visit at 6 months. All patients were seen in office at 12 months. The mean time to first diagnosis of clinically actionable events was earlier in the Remote arm (5.7 months) than in the Control arm (7.7 months). Three (2%) of the 190 events in the Control arm and 446 (66%) of 676 events in the Remote arm were identified remotely. The strategic use of remote pacemaker interrogation follow-up detects actionable events that are potentially important more quickly and more frequently than transtelephonic rhythm strip recordings. The use of transtelephonic rhythm strips for pacemaker follow-up is of little value except for battery status determinations. (PREFER [Pacemaker Remote Follow-up Evaluation and Review]; NCT00294645).

Progress in American Superconductor's HTS wire and optimization for fault current limiting systems

NASA Astrophysics Data System (ADS)

Malozemoff, Alexis P.

2016-11-01

American Superconductor has developed composite coated conductor tape-shaped wires using high temperature superconductor (HTS) on a flexible substrate with laminated metal stabilizer. Such wires enable many applications, each requiring specific optimization. For example, coils for HTS rotating machinery require increased current density J at 25-50 K. A collaboration with Argonne, Brookhaven and Los Alamos National Laboratories and several universities has increased J using an optimized combination of precipitates and ion irradiation defects in the HTS. Major commercial opportunities also exist to enhance electric power grid resiliency by linking substations with distribution-voltage HTS power cables [10]. Such links provide alternative power sources if one substation's transmission-voltage power is compromised. But they must also limit fault currents which would otherwise be increased by such distribution-level links. This can be done in an HTS cable, exploiting the superconductor-to-resistive transition when current exceeds the wires' critical J. A key insight is that such transitions are usually nonuniform; so the wire must be designed to prevent localized hot spots from damaging the wire or even generating gas bubbles in the cable causing dielectric breakdown. Analysis shows that local heating can be minimized by increasing the composite tape's total thickness, decreasing its total resistance in the normal state and decreasing its critical J. This conflicts with other desirable wire characteristics. Optimization of these conflicting requirements is discussed.

Magnetization mechanisms in ordered arrays of polycrystalline Fe{sub 100−x}Co{sub x} nanowires

DOE Office of Scientific and Technical Information (OSTI.GOV)

Viqueira, M. S.; Bajales, N.; Urreta, S. E.

2015-05-28

Magnetization reversal processes and coercivity mechanisms in polycrystalline Fe{sub 100−x}Co{sub x} nanowire arrays, resulting from an AC electrodeposition process, are investigated. The array coercivity is described on the basis of polarization reversal mechanisms operating in individual wires, under the effect of inter-wire dipolar interactions described by a mean field approximation. For individual wires, a reversal mechanism involving the nucleation and further expansion of domain-wall like spin configuration is considered. The wires have a mean grain size larger than both the nanowire diameter and the exchange length, so localized and non-cooperative nucleation modes are considered. As the Co content increases, themore » alloy saturation polarization gradually decreases, but the coercive field and the relative remanence of the arrays increase, indicating that they are not controlled by the shape anisotropy in all the composition range. The coercive field dependence on the angle between the applied field and the wire long axis is not well described by reversal mechanisms involving nucleation and further displacement of neither vortex nor transverse ideal domain walls. On the contrary, the angular dependence of the coercive field observed at room temperature is well predicted by a model considering nucleation of inverse domains by localized curling, in regions smaller than the grain size, exhibiting quite small aspect ratios as compared to those of the entire nanowire. In arrays with higher Co contents, a transition from an initial (small angle) localized curling nucleation mechanism to another one, involving localized coherent rotation is observed at about π/4.« less

Electrocardiograms with pacemakers: accuracy of computer reading.

PubMed

Guglin, Maya E; Datwani, Neeta

2007-04-01

We analyzed the accuracy with which a computer algorithm reads electrocardiograms (ECGs) with electronic pacemakers (PMs). Electrocardiograms were screened for the presence of electronic pacing spikes. Computer-derived interpretations were compared with cardiologists' readings. Computer-drawn interpretations required revision by cardiologists in 61.3% of cases. In 18.4% of cases, the ECG reading algorithm failed to recognize the presence of a PM. The misinterpretation of paced beats as intrinsic beats led to multiple secondary errors, including myocardial infarctions in varying localization. The most common error in computer reading was the failure to identify an underlying rhythm. This error caused frequent misidentification of the PM type, especially when the presence of normal sinus rhythm was not recognized in a tracing with a DDD PM tracking the atrial activity. The increasing number of pacing devices, and the resulting number of ECGs with pacing spikes, mandates the refining of ECG reading algorithms. Improvement is especially needed in the recognition of the underlying rhythm, pacing spikes, and mode of pacing.

Roles of interleukin-9 in the growth and cholecystokinin-induced intracellular calcium signaling of cultured interstitial cells of Cajal.

PubMed

Gong, Yaoyao; Huang, Lei; Cheng, Wenfang; Li, Xueliang; Lu, Jia; Lin, Lin; Si, Xinmin

2014-01-01

Interstitial cells of Cajal (ICC) are pacemaker cells in the gastrointestinal (GI) tract and loss of ICC is associated with many GI motility disorders. Previous studies have shown that ICC have the capacity to regenerate or restore, and several growth factors are critical to their growth, maintenance or regeneration. The present study aimed to investigate the roles of interleukin-9 (IL-9) in the growth, maintenance and pacemaker functions of cultured ICC. Here, we report that IL-9 promotes proliferation of ICC, and culturing ICC with IL-9 enhances cholecystokinin-8-induced Ca²⁺ transients, which is probably caused by facilitating maintenance of ICC functions under culture condition. We also show co-localizations of cholecystokinin-1 receptor and IL-9 receptor with c-kit by double-immunohistochemical labeling. In conclusion, IL-9 can promote ICC growth and help maintain ICC functions; IL-9 probably performs its functions via IL-9 receptors on ICC.

Programmable Pacemaker

NASA Technical Reports Server (NTRS)

1996-01-01

Released in 1995, the Trilogy cardiac pacemaker is the fourth generation of a unit developed in the 1970s by NASA, Johns Hopkins Applied Physics Laboratory and St. Jude Medical's Cardiac Rhythm Management Division (formerly known as Pacesetter Systems, Inc.). The new system incorporates the company's PDx diagnostic and programming software and a powerful microprocessor that allows more functions to be fully automatic and gives more detailed information on the patient's health and the performance of the pacing systems. The pacemaker incorporates bidirectional telemetry used for space communications for noninvasive communication with the implanted pacemaker, smaller implantable pulse generators from space microminiaturization, and longer-life batteries from technology for spacecraft electrical power systems.

Lithium-cupric sulfide cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cuesta, A.J.; Bump, D.D.

1980-01-01

Lithium cells have become the primary power source for cardiac pacemakers due to their reliability and longevity at low current drain rates. A lithium-cupric sulfide cell was developed which makes maximum use of the shape of a pacemaker's battery compartment. The cell has a stable voltage throughout 90% of its lifetime. It then drops to a second stable voltage before depletion. The voltage drop creates a small decrease in pacemaker rate, which alerts the physician to replace the pacemaker. No loss of capacity due to self-discharge as been seen to date, and cells have proven to be safe under extrememore » conditions. 2 refs.« less

Gene therapy to develop a genetically engineered cardiac pacemaker.

PubMed

Glenn, Christopher M; Pogwizd, Steven M

2003-01-01

While cardiac pacemakers are frequently used for the treatment of bradydysrhythmias (from diseases of the cardiac conduction system), their use is still limited by complications that can be life-threatening and expensive. Genetic engineering approaches offer an opportunity to modulate cellular automaticity in a manner that could have significant therapeutic potential. It is well known that ventricular myocytes exhibit a more negative diastolic potential than do pacemaker cells, in large part because of the inward rectifying potassium current/K1 (which pacemaker cells lack). Taking advantage of these intrinsic electrophysiological differences, a biological pacemaker has recently been developed by Miake et al (Nature 2002; 419:132-133) using adenoviral gene transfer approaches. By isolating the gene responsible for/K1 (the Kir2.1 gene), mutating it to make it a dysfunctional channel (a dominant-negative), inserting the mutated gene into an adenoviral vector, and delivering the virus to the hearts of guinea pigs, the investigators were able to successfully convert some ventricular myocytes to pacemaker cells. While issues of safety and long-term efficacy need to be further established, the results of these experiments provide proof of principle that gene transfer offers great promise for treatment of electrophysiological disorders including conduction system disease.

Role of sinoatrial node architecture in maintaining a balanced source-sink relationship and synchronous cardiac pacemaking

PubMed Central

Unudurthi, Sathya D.; Wolf, Roseanne M.; Hund, Thomas J.

2014-01-01

Normal heart rhythm (sinus rhythm) depends on regular activity of the sinoatrial node (SAN), a heterogeneous collection of specialized myocytes in the right atrium. SAN cells, in general, possess a unique electrophysiological profile that promotes spontaneous electrical activity (automaticity). However, while automaticity is required for normal pacemaking, it is not necessarily sufficient. Less appreciated is the importance of the elaborate structure of the SAN complex for proper pacemaker function. Here, we review the important structural features of the SAN with a focus on how these elements help manage a precarious balance between electrical charge generated by the SAN (“source”) and the charge needed to excite the surrounding atrial tissue (“sink”). We also discuss how compromised “source-sink” balance due, for example to fibrosis, may promote SAN dysfunction, characterized by slow and/or asynchronous pacemaker activity and even failure, in the setting of cardiovascular disease (e.g., heart failure, atrial fibrillation). Finally, we discuss implications of the “source-sink” balance in the SAN complex for cell and gene therapies aimed at creating a biological pacemaker as replacement or bridge to conventional electronic pacemakers. PMID:25505419

Embryological development of pacemaker hierarchy and membrane currents related to the function of the adult sinus node: implications for autonomic modulation of biopacemakers.

PubMed

Opthof, Tobias

2007-02-01

The sinus node is an inhomogeneous structure. In the embryonic heart all myocytes have sinus node type pacemaker channels (I (f)) in their sarcolemma. Shortly before birth, these channels disappear from the ventricular myocytes. The response of the adult sinus node to changes in the interstitium, in particular to (neuro)transmitters, results from the interplay between the responses of all of its constituent cells. The response of the whole sinus node cannot be simply deduced from these cellular responses, because all cells have different responses to specific agonists. A biological pacemaker will be more homogeneous. Therefore it can be anticipated that tuning of cycle length may be problematic. It is discussed that efforts to create a biological pacemaker responsive to vagal stimulation, may be counterproductive, because it may have the potential risk of 'standstill' of the biological pacemaker. A normal sinus node remains spontaneously active at high concentrations of acetylcholine, because it has areas that are unresponsive to acetylcholine. The same is pertinent to other substances with a negative chronotropic effect. Such functional inhomogeneity is lacking in biological pacemakers.

Electroluminescence of a polythiophene molecular wire suspended between a metallic surface and the tip of a scanning tunneling microscope.

PubMed

Reecht, Gaël; Scheurer, Fabrice; Speisser, Virginie; Dappe, Yannick J; Mathevet, Fabrice; Schull, Guillaume

2014-01-31

The electroluminescence of a polythiophene wire suspended between a metallic surface and the tip of a scanning tunneling microscope is reported. Under positive sample voltage, the spectral and voltage dependencies of the emitted light are consistent with the fluorescence of the wire junction mediated by localized plasmons. This emission is strongly attenuated for the opposite polarity. Both emission mechanism and polarity dependence are similar to what occurs in organic light emitting diodes (OLED) but at the level of a single molecular wire.

Comment on 'Hy-wire measurements of atmospheric potential' by R. H. Holzworth

NASA Technical Reports Server (NTRS)

Markson, R.

1984-01-01

It is shown that the Hy-wire fluctuations in atmospheric potential measured by Holzworth (1983) were not changes in the global circuit. The close association between the Hy-wire potential variations and meteorological changes, as well as the lack of correlation between the potential and the Carnegie curve, indicates that the tethered balloon measurements were responding to local meteorological factors. The abnormally high potentials and the reversed curvature of the potential profiles suggest that the Hy-wire apparatus was not measuring atmospheric potentials accurately.

Numerical and experimental analysis of inhomogeneities in SMA wires induced by thermal boundary conditions

NASA Astrophysics Data System (ADS)

Furst, Stephen J.; Crews, John H.; Seelecke, Stefan

2012-11-01

Published data on NiTi wire tensile tests display a surprising variety of results even though the same material has been studied. Hysteresis shapes can be observed that range from box- to cigar-like. In some cases, the variation may be the result of different post-fabrication treatment, such as annealing or cold working procedures. However, oftentimes local data are generated from average stress/strain concepts on the basis of global force and end displacement measurements. It is well known among experimentalists that this has a smoothening effect on data, but there is an additional, less well-known mechanism at work as well. This effect is due to thermomechanical coupling and the thermal boundary condition at the ends of the wires, and it manifests itself in a strong data dependence on the length of the employed specimen. This paper illustrates the effects of a thermal boundary layer in a 1D wire by means of an experimental study combined with a simulation based on the fully coupled momentum and energy balance equations. The system is modeled using COMSOL FEA software to simulate the distribution of strain, temperature, resistivity, and phase fractions. The local behavior is then integrated over the length of the wire to predict the expected behavior of the bulk wire as observed at its endpoints. Then, simulations are compared with results from a tensile test of a 100 mum diameter Dynalloy Flexinol wire between two large, steel clamps. Each step of the tensile test experiment is carefully controlled and then simulated via the boundary and initial conditions of the model. The simulated and experimental results show how the thermal boundary layer affects different length SMA wires and how the inhomogeneity prevents transition to austenite at the wire endpoints. Accordingly, shorter wires tend to be softer (more martensitic) than longer wires and exhibit a large reduction in recoverable strain because a larger percentage of their total length is impacted by the thermal boundary.

Implantable automatic scanning pacemaker for termination of supraventricular tachycardia.

PubMed

Spurrell, R A; Nathan, A W; Bexton, R S; Hellestrand, K J; Nappholz, T; Camm, A J

1982-03-01

Thirteen patients suffering from reentrant supraventricular tachycardia have undergone implantation of a scanning extrastimulus pacemaker. This pacemaker is fully implanted and automatic, and it requires no external control device to activate or control it. The pacemaker is activated when tachycardia occurs. After four cycles an extrastimulus is induced with a preset coupling time from a sensed intracardiac potential, and every four cycles thereafter a further extrastimulus occurs, but on each occasion there is a decrement in coupling cycle by 6 ms until 90 ms of the cardiac cycle has been scanned by extrastimuli. When necessary, two extrastimuli can be introduced with a fixed but preset coupling time between them. Every four beats two extrastimuli are induced but the coupling time between the spontaneous cardiac potential and the first stimulus is decreased by 6 ms until 90 ms of the cardiac cycle has been scanned. The coupling time between the two stimuli is fixed throughout the scan. When termination of tachycardia occurs the successful timing variables are retained in the pacemaker memory so that at the onset of the next episode of tachycardia these settings are used first. Pacemaker pulse width, sensitivity, tachycardia trigger rate, coupling intervals for both stimuli and the use of single or double extrastimuli are all programmable transcutaneously. Three patients required single, and seven patients double ventricular premature stimuli; three patients required double atrial premature stimuli for termination of tachycardia. Despite frequent attacks of tachycardia before implantation, only two patients had a sustained attack of tachycardia after pacemaker implantation.

Angiotensin II promotes differentiation of mouse c-kit-positive cardiac stem cells into pacemaker-like cells

PubMed Central

XUE, CHENG; ZHANG, JUN; LV, ZHAN; LIU, HUI; HUANG, CONGXIN; YANG, JING; WANG, TEN

2015-01-01

Cardiac stem cells (CSCs) can differentiate into cardiac muscle-like cells; however, it remains unknown whether CSCs may possess the ability to differentiate into pacemaker cells. The aim of the present study was to determine whether angiotensin II (Ang II) could promote the specialization of CSCs into pacemaker-like cells. Mouse CSCs were treated with Ang II from day 3–5, after cell sorting. The differentiation potential of the cells was then analyzed by morphological analysis, flow cytometry, reverse transcription-polymerase chain reaction, immunohistochemistry and patch clamp analysis. Treatment with Ang II resulted in an increased number of cardiac muscle-like cells (32.7±4.8% vs. 21.5±4.8%; P<0.05), and inhibition of smooth muscle-like cells (6.2±7.3% vs. 20.5±5.1%; P<0.05). Following treatment with Ang II, increased levels of the cardiac progenitor-specific markers GATA4 and Nkx2.5 were observed in the cells. Furthermore, the transcript levels of pacemaker function-related genes, including hyperpolarization-activated cyclic nucleotide-gated (HCN)2, HCN4, T-box (Tbx)2 and Tbx3, were significantly upregulated. Immunofluorescence analysis confirmed the increased number of pacemaker-like cells. The pacemaker current (If) was recorded in the cells derived from CSCs, treated with Ang II. In conclusion, treatment of CSCs with Ang II during the differentiation process modified cardiac-specific gene expression and resulted in the enhanced formation of pacemaker-like cells. PMID:25572000

Radioisotope-powered cardiac pacemaker program. Clinical studies of the nuclear pacemaker model NU-5. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1980-06-01

Beginning in February, 1970, the Nuclear Materials and Equipment Corporation (NUMEC) undertook a program to design, develop and manufacture a radioisotope powered cardiac pacemaker system. The scope of technical work was specified to be: establish system, component, and process cost reduction goals using the prototype Radioisotope Powered Cardiac Pacemaker (RCP) design and develop production techniques to achieve these cost reduction objectives; fabricate radioisotope powered fueled prototype cardiac pacemakers (RCP's) on a pilot production basis; conduct liaison with a Government-designated fueling facility for purposes of defining fueling requirements, fabrication and encapsulation procedures, safety design criteria and quality control and inspection requirements;more » develop and implement Quality Assurance and Reliability Programs; conduct performance, acceptance, lifetime and reliability tests of fueled RCP's in the laboratory; conduct liaison with the National Institutes of Health and with Government specified medical research institutions selected for the purpose of undertaking clinical evaluation of the RCP in humans; monitor and evaluate, on a continuing basis, all test data; and perform necessary safety analyses and tests. Pacemaker designs were developed and quality assurance and manufacturing procedures established. Prototype pacemakers were fabricated. A total of 126 radioisotope powered units were implanted and have been followed clinically for approximately seven years. Four (4) of these units have failed. Eighty-three (83) units remain implanted and satisfactorily operational. An overall failure rate of less than the target 0.15% per month has been achieved.« less

Pacemaker implantation after catheter ablation for atrial fibrillation.

PubMed

Deshmukh, Abhishek J; Yao, Xiaoxi; Schilz, Stephanie; Van Houten, Holly; Sangaralingham, Lindsey R; Asirvatham, Samuel J; Friedman, Paul A; Packer, Douglas L; Noseworthy, Peter A

2016-01-01

Sinus node dysfunction requiring pacemaker implantation is commonly associated with atrial fibrillation (AF), but may not be clinically apparent until restoration of sinus rhythm with ablation or cardioversion. We sought to determine frequency, time course, and predictors for pacemaker implantation after catheter ablation, and to compare the overall rates to a matched cardioversion cohort. We conducted a retrospective analysis using a large US commercial insurance database and identified 12,158 AF patients who underwent catheter ablation between January 1, 2005 and December 31, 2012. Over an average of 2.4 years of follow-up, 5.6 % of the patients underwent pacemaker implantation. Using the Cox proportional hazards models, we found that risk of risks of pacemaker implantation was associated with older age (50-64 and ≥65 versus <50 years), female gender, higher CHADS2 score (≥2 and 1 versus 0), higher Charlson index (≥2 versus 0-1), certain baseline comorbidities (conduction disorder, coronary atherosclerosis, and congestive heart failure), and the year of ablation. There was no significant difference in the risk of pacemaker implantation between ablation patients and propensity score (PS)-matched cardioversion groups (3.5 versus. 4.1 % at 1 year and 8.8 versus 8.3 % at 5 years). Overall, pacemaker implantation occurs in about 1/28 patients within 1 year of catheter ablation. The overall implantation rate decreased between 2005 and 2012. Furthermore, the risk after ablation is similar to cardioversion, suggesting that patients require pacing due to a common underlying electrophysiologic substrate, rather than the ablation itself.

Characteristics and Prognosis of Pacemaker-Identified New-Onset Atrial Fibrillation in Japanese People.

PubMed

Ogino, Yutaka; Ishikawa, Toshiyuki; Ishigami, Tomoaki; Matsumoto, Katsumi; Hosoda, Junya; Iguchi, Kouhei; Matsushita, Hirooki; Taguchi, Yuka; Horiguchi, Yoriko; Kimura, Kazuo

2017-05-25

The characteristics and prognosis of implanted pacemaker-identified new-onset atrial fibrillation (AF) in Japanese people has not been well evaluated.Methods and Results:A total of 395 consecutive patients with newly implanted pacemakers were retrospectively analyzed between January 2010 and December 2015 at Yokohama City University Hospital. Patients with a prior history of AF, VVI mode pacemaker, congenital heart disease, severe valvular heart disease, and cardiovascular surgery before pacemaker implantation were excluded. Among the remaining patients, 44 (21.3%) developed new AF during follow-up (mean follow-up, 1,115±651 days; range, 9-2,176 days). Patients with new-onset AF had a significantly higher CHADS 2 score (2.09±1.27 vs. 1.31±1.08, P<0.001) and CHA 2 DS 2 -VASc score (3.00±1.39 vs. 2.26±1.19, P<0.001) compared with those without new-onset AF. On Cox regression analysis only age at implantation was significantly correlated with new-onset AF. Interestingly, the incidence of hospitalization due to heart failure was significantly higher in the new-onset AF than in the without new-onset AF group. A total of 21.3% of pacemaker-implanted patients with high CHADS 2 and CHA 2 DS 2 -VASc scores developed new-onset AF during a mean follow-up of 3.1 years; and pacemaker-identified AF was associated with an increased risk of worsening heart failure.

Genetic Elimination of GABAergic Neurotransmission Reveals Two Distinct Pacemakers for Spontaneous Waves of Activity in the Developing Mouse Cortex

PubMed Central

Easton, Curtis R.; Weir, Keiko; Scott, Adina; Moen, Samantha P.; Barger, Zeke; Folch, Albert; Hevner, Robert F.

2014-01-01

Many structures of the mammalian CNS generate propagating waves of electrical activity early in development. These waves are essential to CNS development, mediating a variety of developmental processes, such as axonal outgrowth and pathfinding, synaptogenesis, and the maturation of ion channel and receptor properties. In the mouse cerebral cortex, waves of activity occur between embryonic day 18 and postnatal day 8 and originate in pacemaker circuits in the septal nucleus and the piriform cortex. Here we show that genetic knock-out of the major synthetic enzyme for GABA, GAD67, selectively eliminates the picrotoxin-sensitive fraction of these waves. The waves that remain in the GAD67 knock-out have a much higher probability of propagating into the dorsal neocortex, as do the picrotoxin-resistant fraction of waves in controls. Field potential recordings at the point of wave initiation reveal different electrical signatures for GABAergic and glutamatergic waves. These data indicate that: (1) there are separate GABAergic and glutamatergic pacemaker circuits within the piriform cortex, each of which can initiate waves of activity; (2) the glutamatergic pacemaker initiates waves that preferentially propagate into the neocortex; and (3) the initial appearance of the glutamatergic pacemaker does not require preceding GABAergic waves. In the absence of GAD67, the electrical activity underlying glutamatergic waves shows greatly increased tendency to burst, indicating that GABAergic inputs inhibit the glutamatergic pacemaker, even at stages when GABAergic pacemaker circuitry can itself initiate waves. PMID:24623764

Pacemaker Implants in Children and Adolescents with Chagas Disease in Brazil: 18-Year Incidence

PubMed Central

Mizzaci, Carolina Christianini; Souza, Thiago Gonçalves Schroder e; Targueta, Gabriel Pelegrineti; Tótora, Ana Paula Frederico; Mateos, Juan Carlos Pachón; Mateos, José Carlos Pachon

2017-01-01

Background: Chagas disease continues to be a serious public health problem, and accounts for 25-30% of the indications for cardiac stimulation in Brazil. Objective: To assess clinical and epidemiological characteristics of patients with Chagas disease, younger than 18 years, who had undergone pacemaker implantation in Brazil between 1994 and 2011, and its temporal trend. Methods: This was a cross-sectional analysis of data from the Brazilian Pacemaker Registry database. The following variables were analyzed: year when pacemaker was implanted, location, age, sex, ethnic group, functional class and the main electrocardiographic findings at baseline. Results: In a total of 183,123 implants performed between 1994 and 2011, 214 implants of cardiac stimulation device in Chagas disease patients aged younger than 18 years were identified. Mean age at implantation was 5.6 ± 6.2 years. Second- and third-degree atrioventricular blocks corresponded to 71% of indications for pacemaker implantation. Fifty-six percent of the procedures were performed in the southeast region. Regarding the total number of pacemaker implants per year, there was a remarkable increase in the implants for all causes. However, time series analysis of the implants in Chagas disease patients younger than 18 years revealed a significant reduction in the annual number of implants. Conclusion: There has been an important reduction in the number of pacemaker implantations among children and adolescents with Chagas disease, suggesting a reduction in the vertical transmission of the parasite. PMID:28699977

Potential for Personal Digital Assistant interference with implantable cardiac devices.

PubMed

Tri, Jeffrey L; Trusty, Jane M; Hayes, David L

2004-12-01

To determine whether the wireless local area network (WLAN) technology, specifically the Personal Digital Assistant (PDA), interferes with implantable cardiac pacemakers and defibrillators. Various pacemakers and defibrillators were tested in vitro at the Mayo Clinic in Rochester, Minn, between March 6 and July 30, 2003. These cardiac devices were exposed to an HP Compaq IPAQ PDA fitted with a Cisco Aironet WLAN card. Initial testing was designed to show whether the Aironet card radiated energy in a consistent pattern from the antenna of the PDA to ensure that subsequent cardiac device testing would not be affected by the orientation of the PDA to the cardiac device. Testing involved placing individual cardiac devices in a simulator and uniformly exposing each device at its most sensitive programmable value to the WLAN card set to maximum power. During testing with the Cisco WLAN Aironet card, all devices programmed to the unipolar or bipolar configuration single- or dual-chamber mode had normal pacing and sensing functions and exhibited no effects of electromagnetic interference except for 1 implantable cardioverter-defibrillator (ICD). This aberration was determined to relate to the design of the investigators' testing apparatus and not to the output of the PDA. The ICD device appropriately identified and labeled the electromagnetic aberration as "noise." We documented no electromagnetic interference caused by the WLAN technology by using in vitro testing of pacemakers and ICDs; however, testing ideally should be completed in vivo to confirm the lack of any clinically important interactions.

'Cardiogenic vertigo'--true vertigo as the presenting manifestation of primary cardiac disease.

PubMed

Newman-Toker, David E; Camargo, Carlos A

2006-03-01

A 90-year-old woman presented to a hospital emergency department with a brief loss of consciousness that was heralded by spinning vertigo lasting approximately 2 min. She had a long history of intermittent brief episodes of rotatory vertigo, presyncope, and non-vertiginous dizziness, occurring either with or without loss of consciousness. Although initially attributed to symptomatic carotid artery stenosis, these episodes persisted, despite surgical restoration of carotid artery blood flow 1 year after her first syncope. Her medical history was otherwise notable for hypertension, mild depression and a gradual decline in gait and balance function attributed to left hip arthritis and older age. Bedside history and examination, non-contrast head CT scan, electrocardiogram, transthoracic echocardiogram, and bedside cardiac telemetry. Sick sinus syndrome or severe reflex bradycardia with asystole causing recurrent, episodic vertigo, presyncope, non-vertiginous dizziness and syncope (Stokes-Adams attacks). Placement of a temporary pacing wire, followed by surgical implantation of a single-chamber ventricular (VVI) pacemaker.

Radiation from mixed multi-planar wire arrays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Safronova, A. S.; Kantsyrev, V. L.; Esaulov, A. A.

2014-03-15

The study of radiation from different wire materials in wire array Z-pinch plasma is a very challenging topic because it is almost impossible to separate different plasmas at the stagnation. A new approach is suggested based on planar wire array (PWA) loads to assess this problem. Multi-planar wire arrays are implemented that consist of few planes, each with the same number of wires and masses but from different wire materials, arranged in parallel rows. In particular, the experimental results obtained with triple PWAs (TPWAs) on the UNR Zebra generator are analyzed with Wire Ablation Dynamics Model, non-local thermodynamic equilibrium kineticmore » model, and 2D radiation magneto-hydrodynamic to illustrate this new approach. In TPWAs, two wire planes were from mid-atomic-number wire material and another plane was from alloyed Al, placed either in the middle or at the edge of the TPWA. Spatial and temporal properties of K-shell Al and L-shell Cu radiations were analyzed and compared from these two configurations of TPWAs. Advantages of the new approach are demonstrated and future work is discussed.« less

Percutaneous tricuspid valvotomy for pacemaker lead-induced tricuspid stenosis

PubMed Central

Patil, Devendra V.; Nabar, Ashish A.; Sabnis, Girish R.; Phadke, Milind S.; Lanjewar, Charan P.; Kerkar, Prafulla G.

2015-01-01

Permanent pacemaker lead-induced tricuspid regurgitation is extremely uncommon. We report a patient with severe tricuspid stenosis detected 10 years after permanent single chamber pacemaker implantation in surgically corrected congenital heart disease. The loop at the level of the tricuspid valve may have caused endothelial injury and eventually led to stenosis. Percutaneous balloon valvotomy for such stenosis has not been reported from India. PMID:26995417

Infectious endocarditis in pacemaker endocardial leads: report of three cases.

PubMed

Cruz-Cruz, F; Espinola-Zavaleta, N; Hernández Lara, J; Iturralde-Torres, P; González-Hermosillo, J A; Romero-Cárdenas, A; Keirns, C; Vargas-Barrón, J

1999-01-01

Three cases of endocarditis affecting endocardial leads of permanent pacemakers are presented with a review of the literature. Vegetations were identified using transesophageal echocardiography. Infection of pacemaker leads is far less common than infection at the site of the pulse generator with greater morbidity and mortality and generally requiring surgical removal of both electrodes and power source. The most frequent infective agents are stahylococcus varieties.

Clinical features and changes in epidemiology of infective endocarditis on pacemaker devices over a 27-year period (1987-2013).

PubMed

Carrasco, Francisco; Anguita, Manuel; Ruiz, Martín; Castillo, Juan Carlos; Delgado, Mónica; Mesa, Dolores; Romo, Elias; Pan, Manuel; Suárez de Lezo, Jose

2016-06-01

Use of cardiac pacing devices has grown in recent years. Our aim was to evaluate changes in epidemiology and clinical features of infective endocarditis (IE) involving pacemaker devices in a large series of IE over the last 27 years (1987-2013). From 1987 to December 2013, 413 consecutive IE cases were diagnosed in our hospital. During this period, 7424 pacemaker devices were implanted (6917 pacemakers, 239 implantable cardiac defibrillators, 158 resynchronization devices, and 110 resynchronization/defibrillator devices). All consecutive cases of IE on pacemaker devices were included and analysed. Infective endocarditis on pacemaker devices represented 6.1% of all endocarditis cases (25 patients), affecting 3.6/1000 of all implanted pacemakers. Its proportion increased from 1.25% of all endocarditis in 1987-1993 to 4.08% in 1994-2000, 7.69% in 2001-2007 and 9.32% in 2008-2013 (P < 0.01). Its incidence also increased from 1.4/1000 of all pacemaker implants in the period of 1987-1993 to 2.5/1000 in 1994-2000, 3.3/1000 in 2001-2007 and 4.5/1000 implanted devices in 2008-2013 (P < 0.05). Mean age of patients was 68 years, and 80% were male. Causative microorganisms predominantly were Staphylococci (84%: Staphylococcus aureus 48%, Staphylococcus epidermidis 36%). Rate of severe complications was high: persistent sepsis in 60% of cases, heart failure in 20%, and stroke in 12%. Device was removed in 19 patients (76%), mostly by surgery (18 of the 19 cases). Early mortality was 24% (33% of medically, 21% of surgically treated patients, P = 0.82). Infective endocarditis on pacemaker devices has shown an increasing incidence during the past decades, representing almost 10% of all IE in the last 6 years. This is a severe disease, with a high rate of severe complications and requiring removal of device in most cases. In spite of therapy, early mortality is high. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

Deformable 3D-2D registration for guiding K-wire placement in pelvic trauma surgery

NASA Astrophysics Data System (ADS)

Goerres, J.; Jacobson, M.; Uneri, A.; de Silva, T.; Ketcha, M.; Reaungamornrat, S.; Vogt, S.; Kleinszig, G.; Wolinsky, J.-P.; Osgood, G.; Siewerdsen, J. H.

2017-03-01

Pelvic Kirschner wire (K-wire) insertion is a challenging surgical task requiring interpretation of complex 3D anatomical shape from 2D projections (fluoroscopy) and delivery of device trajectories within fairly narrow bone corridors in proximity to adjacent nerves and vessels. Over long trajectories ( 10-25 cm), K-wires tend to curve (deform), making conventional rigid navigation inaccurate at the tip location. A system is presented that provides accurate 3D localization and guidance of rigid or deformable surgical devices ("components" - e.g., K-wires) based on 3D-2D registration. The patient is registered to a preoperative CT image by virtually projecting digitally reconstructed radiographs (DRRs) and matching to two or more intraoperative x-ray projections. The K-wire is localized using an analogous procedure matching DRRs of a deformably parametrized model for the device component (deformable known-component registration, or dKC-Reg). A cadaver study was performed in which a K-wire trajectory was delivered in the pelvis. The system demonstrated target registration error (TRE) of 2.1 ± 0.3 mm in location of the K-wire tip (median ± interquartile range, IQR) and 0.8 ± 1.4º in orientation at the tip (median ± IQR), providing functionality analogous to surgical tracking / navigation using imaging systems already in the surgical arsenal without reliance on a surgical tracker. The method offers quantitative 3D guidance using images (e.g., inlet / outlet views) already acquired in the standard of care, potentially extending the advantages of navigation to broader utilization in trauma surgery to improve surgical precision and safety.

Ballistic pulse propagation in quantum wire waveguides: Toward localization and control of electron wave packets in space and time

NASA Astrophysics Data System (ADS)

Hayata, K.; Tsuji, Y.; Koshiba, M.

1992-10-01

A theoretical formulation of electron pulse propagation in quantum wire structures with mesoscopic scale cross sections is presented, assuming quantum ballistic transport of electron wave packets over a certain characteristic length. As typical mesoscopic structures for realizing coherent electron transmission, two traveling-wave configurations are considered: straight quantum wire waveguides and quantum wire bend structures (quantum whispering galleries). To estimate temporal features of the pulse during propagation, the walk off, the dispersion, and the pulse coherence lengths are defined as useful characteristic lengths. Numerical results are shown for ultrashort pulse propagation through rectangular wire waveguides. Effects due to an external electric field are discussed as well.

Optimization of microwire/glass-fibre reinforced polymer composites for wind turbine application

NASA Astrophysics Data System (ADS)

Qin, F. X.; Peng, H. X.; Chen, Z.; Wang, H.; Zhang, J. W.; Hilton, G.

2013-11-01

We here report a comprehensive study of glass-fibre reinforced polymers (GFRP) incorporating ferromagnetic microwires for microwave absorption applications. With wire addition, a remarkable dependence of microwave absorption performance appears on the local properties of wires such as wire geometry and the mesostructure such as inter-wire spacing, as well as the embedded depth of the wires layer. The impact testing further demonstrates that the metallic microwires can to some extent improve the impact performance. Based on both the absorption and impact behavior, we propose an optimized design of the microwire/GFRP composites to achieve simultaneous best possible absorption and impact performance for multifunctional applications in aeronautical structures and wind turbines.

Dynamics of vapor emissions at wire explosion thresholda)

NASA Astrophysics Data System (ADS)

Belony, Paul A.; Kim, Yong W.

2010-10-01

X-pinch plasmas have been actively studied in the recent years. Numerical simulation of the ramp-up of metallic vapor emissions from wire specimens shows that under impulsive Ohmic heating the wire core invariably reaches a supercritical state before explosion. The heating rate depends sensitively on the local wire resistance, leading to highly variable vapor emission flux along the wire. To examine the vapor emission process, we have visualized nickel wire explosions by means of shock formation in air. In a single explosion as captured by shadowgraphy, there usually appear several shocks with spherical or cylindrical wave front originating from different parts of the wire. Growth of various shock fronts in time is well characterized by a power-law scaling in one form or another. Continuum emission spectra are obtained and calibrated to measure temperature near the explosion threshold. Shock front structures and vapor plume temperature are examined.

Effect of thickness of insulation coating on temperature of electrically exploded tungsten wires in vacuum

NASA Astrophysics Data System (ADS)

Shi, Huantong; Zou, Xiaobing; Wang, Xinxin

2017-07-01

This paper reports an interesting observation of great differences in the temperature of exploded wires with insulation coating of different thicknesses. Two kinds of polyimide-coated tungsten wires were used with the same conductive diameter 12.5 μm but a different thickness of coating, 0.75-2.25 μm and 2.25-4.25 μm, respectively. The specific energy reconstructed from the current and voltage signals was quite close for the tested wires. However, the exploding scenario, obtained from Mach-Zehnder interferograms, showed great differences: a neutral outer-layer was observed around the thick-coated wire, which was absent for the thin-coated wire; and the calculated electron density and local thermal equilibrium temperature were much higher for thick-coated wires. The heat-preserving neutral layer formed by the decomposition of the insulation was supposed to be the cause of this phenomenon.

Method of preventing leakage of a fluid along and through an insulating jacket of a thermocouple

DOEpatents

Thermos, Anthony Constantine; Rahal, Fadi Elias

2002-01-01

A thermocouple assembly includes a thermocouple; a plurality of lead wires extending from the thermocouple; an insulating jacket extending along and enclosing the plurality of leads; and at least one internally sealed area within the insulating jacket to prevent fluid leakage along and within the insulating jacket. The invention also provides a method of preventing leakage of a fluid along and through an insulating jacket of a thermocouple including the steps of a) attaching a plurality of lead wires to a thermocouple; b) adding a heat sensitive pseudo-wire to extend along the plurality of lead wires; c) enclosing the lead wires and pseudo-wire inside an insulating jacket; d) locally heating axially spaced portions of the insulating jacket to a temperature which melts the pseudo-wire and fuses it with an interior surface of the jacket.

A Sodium Leak Current Regulates Pacemaker Activity of Adult Central Pattern Generator Neurons in Lymnaea Stagnalis

PubMed Central

Lu, Tom Z.; Feng, Zhong-Ping

2011-01-01

The resting membrane potential of the pacemaker neurons is one of the essential mechanisms underlying rhythm generation. In this study, we described the biophysical properties of an uncharacterized channel (U-type channel) and investigated the role of the channel in the rhythmic activity of a respiratory pacemaker neuron and the respiratory behaviour in adult freshwater snail Lymnaea stagnalis. Our results show that the channel conducts an inward leak current carried by Na+ (ILeak-Na). The ILeak-Na contributed to the resting membrane potential and was required for maintaining rhythmic action potential bursting activity of the identified pacemaker RPeD1 neurons. Partial knockdown of the U-type channel suppressed the aerial respiratory behaviour of the adult snail in vivo. These findings identified the Na+ leak conductance via the U-type channel, likely a NALCN-like channel, as one of the fundamental mechanisms regulating rhythm activity of pacemaker neurons and respiratory behaviour in adult animals. PMID:21526173

Clinical assessment of pacemaker power sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bilitch, M.; Parsonnet, V.; Furman, S.

1980-01-01

The development of power sources for cardiac pacemakers has progressed from a 15-year usage of mercury-zinc batteries to widely used and accepted lithium cells. At present, there are about 6 different types of lithium cells incorporated into commercially distributed pacemakers. The authors reviewed experience over a 5-year period with 1711 mercury-zinc, 130 nuclear (P238) and 1912 lithium powered pacemakers. The lithium units have included 698 lithium-iodide, 270 lithium-silver chromate, 135 lithium-thionyl chloride, 31 lithium-lead and 353 lithium-cupric sulfide batteries. 57 of the lithium units have failed (91.2% component failure and 5.3% battery failure). 459 mercury-zinc units failed (25% component failuremore » and 68% battery depletion). The data show that lithium powered pacemaker failures are primarily component, while mercury-zinc failures are primarily battery related. It is concluded that mercury-zinc powered pulse generators are obsolete and that lithium and nuclear (P238) power sources are highly reliable over the 5 years for which data are available. 3 refs.« less

Mangalith: a new lithium pacemaker battery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gerbier, G.; Lehmann, G.

1980-01-01

An original lithium battery system is being developed for pacemaker application. The material used, lithium-manganese dioxide, industrially available at the present time for a variety of electronic applications, has been modified and adapted for pacemaker power requirements. The utilization of a different modification of manganese dioxide offers performance advantages. The cell technology is described and performance comparisons between this new cathode material and the industrial counterpart are reported. 7 refs.

Venous obstruction in permanent pacemaker patients: an isotopic study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pauletti, M.; Di Ricco, G.; Solfanelli, S.

1981-01-01

Isotope venography was used to study the venous circulation proximal to the superior vena cava in two groups of pacemaker patients, one with a single endocavitary electrode and the other with multiple pacing catheters. A control group of patients without pacemakers was also studied. Numerous abnormalities were found, especially in the group with multiple electrodes. These findings suggest that venous obstruction is a common complication of endocardial pacing.

Calcium Homeostatasis and Mitochondrial Dysfunction in Dopaminergic Neurons of the Substantia Nigra

DTIC Science & Technology

2010-03-01

discovery that calcium entry through L-type channels during normal pacemaking elevates the sensitivity of SNc dopaminergic neurons to toxins; • the...discovery that L-type calcium channels participate in but are not necessary for pacemaking; • the discovery that serum concentration of the...FDA approved doses; • the discovery that calcium entry through L-type channels during pacemaking elevates mitochondrial oxidant stress and leads

The neurochemical basis of photic entrainment of the circadian pacemaker

NASA Technical Reports Server (NTRS)

Rea, Michael A.; Buckley, Becky; Lutton, Lewis M.

1992-01-01

Circadian rhythmicity in mammals is controlled by the action of a light-entrainable hypothalamus, in association with two cell clusters known as the supra chiasmatic nuclei (SCN). In the absence of temporal environmental clues, this pacemaker continues to measure time by an endogenous mechanism (clock), driving biochemical, physiological, and behavioral rhythms that reflect the natural period of the pacemaker oscillation. This endogenous period usually differs slightly from 24 hours (i.e., circadian). When mammals are maintained under a 24 hour light-dark (LD) cycle, the pacemaker becomes entrained such that the period of the pacemaker oscillation matches that of the LD cycle. Potentially entraining photic information is conveyed to the SCN via a direct retinal projection, the retinohypothalamic tract (RHT). RHT neurotransmission is thought to be mediated by the release of excitatory amino acids (EAA) in the SCN. In support of this hypothesis, recent experiments using nocturnal rodents have shown that EAA antagonists block the effects of light on pacemaker-driven behavioral rhythms, and attenuate light induced gene expression in SCN cells. An understanding of the neurochemical basis of the photic entrainment process would facilitate the development of pharmacological strategies for maintaining synchrony among shift workers in environments, such as the Space Station, which provide unreliable or conflicting temporal photic clues.

Safety of Laser Interstitial Thermal Therapy in Patients With Pacemakers.

PubMed

Grewal, Sanjeet S; Gorny, Krzysztof R; Favazza, Christopher P; Watson, Robert E; Kaufmann, Timothy J; Van Gompel, Jamie J

2018-02-10

Laser interstitial thermal therapy (LiTT) has increasingly been used as a treatment option for medically refractory epilepsy, tumors, and radiation necrosis. The use of LiTT requires intraoperative magnetic resonance (MR) thermography. This can become an issue in patients with other implanted therapeutic devices such as pacemakers and vagal nerve stimulators due to concerns regarding increases in the specific absorption rate (SAR). This is a technical case report demonstrating a successfully and safely performed LiTT in a 1.5-T magnetic resonance imaging (MRI) in a patient with a pacemaker for mesial temporal sclerosis. An 83-yr-old gentleman who had an implanted cardiac pacemaker presented with medically intractable epilepsy and was confirmed to have mesial temporal sclerosis on imaging. Video electroencephalography demonstrated concordant ipsilateral seizures and semiology. He underwent LiTT for ablation of the mesial temporal lobe. This was performed with the below described protocol with a cardiology nurse monitoring the patient's cardiac condition and a physicist monitoring SAR, and MR imaging quality without any adverse events. This study reports on a protocol of cardiac and MR SAR to safely perform MR-guided LiTT in the setting of traditional pacemakers in patients who are not pacemaker dependent. Copyright © 2018 by the Congress of Neurological Surgeons

A prospective clinical study to evaluate the safety and performance of wireless localization of nonpalpable breast lesions using radiofrequency identification technology.

PubMed

Dauphine, Christine; Reicher, Joshua J; Reicher, Murray A; Gondusky, Christina; Khalkhali, Iraj; Kim, Michelle

2015-06-01

The purpose of this study was to evaluate the safety and performance of localizing nonpalpable breast lesions using radiofrequency identification technology. Twenty consecutive women requiring preoperative localization of a breast lesion were recruited. Subjects underwent placement of both a hook wire and a radiofrequency identification tag immediately before surgery. The radiofrequency identification tag was the primary method used by the operating surgeon to localize each lesion during excision, with the hook wire serving as backup in case of tag migration or failed localization. Successful localization with removal of the intended lesion was the primary outcome measured. Tag migration and postoperative infection were also noted to assess safety. Twenty patients underwent placement of a radiofrequency identification tag, 12 under ultrasound guidance and eight with stereotactic guidance. In all cases, the radiofrequency identification tag was successfully localized by the reader at the level of the skin before incision, and the intended lesion was removed along with the radiofrequency identification tag. There were no localization failures and no postoperative infections. Tag migration did not occur before incision, but in three cases, occurred as the lesion was being retracted with fingers to make the final cut along the deep surface of the specimen. In this initial clinical study, radiofrequency tags were safe and able to successfully localize nonpalpable breast lesions. Radiofrequency identification technology may represent an alternative method to hook wire localization.

An approach to ablate and pace:AV junction ablation and pacemaker implantation performed concurrently from the same venous access site.

PubMed

Issa, Ziad F

2007-09-01

Atrioventricular junction (AVJ) ablation combined with permanent pacemaker implantation (the "ablate and pace" approach) remains an acceptable alternative treatment strategy for symptomatic, drug-refractory atrial fibrillation (AF) with rapid ventricular response. This case series describes the feasibility and safety of catheter ablation of the AVJ via a superior vena caval approach performed during concurrent dual-chamber pacemaker implantation. A total of 17 consecutive patients with symptomatic, drug-refractory, paroxysmal AF underwent combined AVJ ablation and dual-chamber pacemaker implantation procedure using a left axillary venous approach. Two separate introducer sheaths were placed into the axillary vein. The first sheath was used for implantation of the pacemaker ventricular lead, which was then connected to the pulse generator. Subsequently, a standard ablation catheter was introduced through the second axillary venous sheath and used for radiofrequency (RF) ablation of the AVJ. After successful ablation, the catheter was withdrawn and the pacemaker atrial lead was advanced through that same sheath and implanted in the right atrium. Catheter ablation of the AVJ was successfully achieved in all patients. The median number of RF applications required to achieve complete AV block was three (range 1-10). In one patient, AV conduction recovered within the first hour after completion of the procedure, and AVJ ablation was then performed using the conventional femoral venous approach. There were no procedural complications. Catheter ablation of the AVJ can be performed successfully and safely via a superior vena caval approach in patients undergoing concurrent dual-chamber pacemaker implantation.

Effects of lubiprostone on pacemaker activity of interstitial cells of cajal from the mouse colon.

PubMed

Jiao, Han-Yi; Kim, Dong Hyun; Ki, Jung Suk; Ryu, Kwon Ho; Choi, Seok; Jun, Jae Yeoul

2014-08-01

Lubiprostone is a chloride (Cl(-)) channel activator derived from prostaglandin E1 and used for managing constipation. In addition, lubiprostone affects the activity of gastrointestinal smooth muscles. Interstitial cells of Cajal (ICCs) are pacemaker cells that generate slow-wave activity in smooth muscles. We studied the effects of lubiprostone on the pacemaker potentials of colonic ICCs. We used the whole-cell patch-clamp technique to determine the pacemaker activity in cultured colonic ICCs obtained from mice. Lubiprostone hyperpolarized the membrane and inhibited the generation of pacemaker potentials. Prostanoid EP1, EP2, EP3, and EP4 antagonists (SC-19220, PF-04418948, 6-methoxypyridine-2-boronc acid N-phenyldiethanolamine ester, and GW627368, respectively) did not block the response to lubiprostone. L-NG-nitroarginine methyl ester (L-NAME, an inhibitor of nitric oxide synthase) and 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ, an inhibitor of guanylate cyclase) did not block the response to lubiprostone. In addition, tetraethylammonium (TEA, a voltage-dependent potassium [K(+)] channel blocker) and apamin (a calcium [Ca(2+)]-dependent K(+) channel blocker) did not block the response to lubiprostone. However, glibenclamide (an ATP-sensitive K(+) channel blocker) blocked the response to lubiprostone. Similar to lubiprostone, pinacidil (an opener of ATP-sensitive K(+) channel) hyperpolarized the membrane and inhibited the generation of pacemaker potentials, and these effects were inhibited by glibenclamide. These results suggest that lubiprostone can modulate the pacemaker potentials of colonic ICCs via activation of ATP-sensitive K(+) channel through a prostanoid EP receptor-independent mechanism.

Effects of Lubiprostone on Pacemaker Activity of Interstitial Cells of Cajal from the Mouse Colon

PubMed Central

Jiao, Han-Yi; Kim, Dong Hyun; Ki, Jung Suk; Ryu, Kwon Ho; Choi, Seok

2014-01-01

Lubiprostone is a chloride (Cl-) channel activator derived from prostaglandin E1 and used for managing constipation. In addition, lubiprostone affects the activity of gastrointestinal smooth muscles. Interstitial cells of Cajal (ICCs) are pacemaker cells that generate slow-wave activity in smooth muscles. We studied the effects of lubiprostone on the pacemaker potentials of colonic ICCs. We used the whole-cell patch-clamp technique to determine the pacemaker activity in cultured colonic ICCs obtained from mice. Lubiprostone hyperpolarized the membrane and inhibited the generation of pacemaker potentials. Prostanoid EP1, EP2, EP3, and EP4 antagonists (SC-19220, PF-04418948, 6-methoxypyridine-2-boronc acid N-phenyldiethanolamine ester, and GW627368, respectively) did not block the response to lubiprostone. L-NG-nitroarginine methyl ester (L-NAME, an inhibitor of nitric oxide synthase) and 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ, an inhibitor of guanylate cyclase) did not block the response to lubiprostone. In addition, tetraethylammonium (TEA, a voltage-dependent potassium [K+] channel blocker) and apamin (a calcium [Ca2+]-dependent K+ channel blocker) did not block the response to lubiprostone. However, glibenclamide (an ATP-sensitive K+ channel blocker) blocked the response to lubiprostone. Similar to lubiprostone, pinacidil (an opener of ATP-sensitive K+ channel) hyperpolarized the membrane and inhibited the generation of pacemaker potentials, and these effects were inhibited by glibenclamide. These results suggest that lubiprostone can modulate the pacemaker potentials of colonic ICCs via activation of ATP-sensitive K+ channel through a prostanoid EP receptor-independent mechanism. PMID:25177167

Living with a pacemaker: patient-reported outcome of a pacemaker system.

PubMed

Magnusson, Peter; Liv, Per

2018-06-04

The aim of this study was to assess among pacemaker patients their overall satisfaction with the pacemaker system, pain, soreness/discomfort, cosmetic results, restrictions due to impaired movement of the shoulder/arm/chest, related sleep disturbances, and concern about possible device malfunction. The seven-item questionnaire was mailed to patients from a single center who had a pacemaker implant or replacement between 2006 and 2016. A higher score indicated worse outcome on a visual analog scale (VAS) of 0-100 mm. The response rate was 75.5% and 342 questionniares were analyzed. Median age of respondents was 77.6 years and 57.0% were males. In total, 65 complications requiring surgery (10 pocket corrections (2.9%), 5 in females) occurred during a median follow-up of 5.6 years.The distribution of the primary outcome had a median score of 5 while the 75th percentile was 13. Cosmetic appearance was significantly associated with reoperation (but not other variables). Overall scores for men and women were 5 vs. 6, respectively, which achieved significance (p = 0.042). Median ratings of pain, soreness/discomfort, cosmetic appearance, range of motion, sleep, and concern about device malfunction were all ≤5. Females reported worse outcomes for all questions, except for cosmetic results and concern about malfunction. The vast majority of patients report excellent overall satisfaction with the pacemaker system, and are not affected by pain, soreness/discomfort, or concern about device malfunction. They also reported favourable outcomes with respect to cosmetic results, shoulder movement, and sleep. However, some patients underwent a surgical correction of the pacemaker pocket.

Evaluation of Safety and Efficacy of Qinming8631 DR Implantable Cardiac Pacemaker in Chinese Patients: A Prospective, Multicenter, Randomized Controlled Trial of the First Domestically Developed Pacemaker of China.

PubMed

Xiang, Mei-Xiang; Wang, Dong-Qi; Xu, Jing; Zhang, Zheng; Hu, Jian-Xin; Wang, Dong-Mei; Gu, Xiang; Liu, He-Ping; Guo, Tao; Yang, Xiang-Jun; Ling, Feng; Lin, Jia-Feng; Cai, Shang-Lang; Zhu, Guo-Bin; Wang, Jian-An

2016-11-20

High cost of imported pacemakers is a main obstacle for Chinese patients suffering from bradyarrhythmia, and a domestically developed pacemaker will help lower the burden. This study aimed to evaluate the safety and efficacy of Qinming8631 DR (Qinming Medical, Baoji, China), the first domestically developed dual-chamber pacemaker of China, compared with a commercially available pacemaker Talos DR (Biotronik, Berlin, Germany) in Chinese patients. A prospective randomized trial was conducted at 14 centers in China. Participants were randomized into trial (Qinming8631 DR) and control (Talos DR) groups. Parameters of the pacing systems were collected immediately after device implantation and during follow-ups. The effective pacing rate at 6-month follow-up was recorded as the primary end point. Electrical properties, magnet response, single- and double-pole polarity conversion, rate response function, and adverse events of the pacing system were analyzed. The Cochran-Mantel-Haenszel Chi-square test, paired t-test, and Wilcoxon signed-rank test were used for measuring primary qualitative outcomes and comparing normally and abnormally distributed measurement data. A total of 225 patients with a diagnosis of bradyarrhythmia and eligible for this study were randomly enrolled into the trial (n = 113) and control (n = 112) groups. They underwent successful pacemaker implantation with acceptable postoperative pacing threshold and sensitivity. Effective pacing rates of trial and control groups were comparable both in the full analysis set and the per protocol set (81.4% vs. 79.5%, P = 0.712 and 95.4% vs. 89.5%, P = 0.143, respectively). In both data sets, noninferiority of the trial group was above the predefined noninferiority limit(-9.5%). This study established the noninferiority of Qinming8631 DR to Talos DR. The safety and efficacy of Qinming8631 DR pacemaker were comparable to those of Talos DR in treating patients with cardiac bradyarrhythmia.

Long-term screening for sleep apnoea in paced patients: preliminary assessment of a novel patient management flowchart by using automatic pacemaker indexes and sleep lab polygraphy.

PubMed

Aimé, Ezio; Rovida, Marina; Contardi, Danilo; Ricci, Cristian; Gaeta, Maddalena; Innocenti, Ester; Cabral Tantchou-Tchoumi, Jacques

2014-10-01

The primary aim of this pilot study was to prospectively assess a flowchart to screen and diagnose paced patients (pts) affected by sleep apnoeas, by crosschecking indexes derived from pacemakers (minute ventilation sensor on-board) with Sleep-Lab Polygraphy (PG) outcomes. Secondarily, "smoothed" long-term pacemaker indexes (all the information between two consecutive follow-up visits) have been retrospectively compared vs. standard short-term pacemaker indexes (last 24h) at each follow-up (FU) visit, to test their correlation and diagnostic concordance. Data from long-term FU of 61 paced pts were collected. At each visit, the standard short-term apnoea+hypopnoea (PM_AHI) index was retrieved from the pacemaker memory. Patients showing PM_AHI ≥ 30 at least once during FU were proposed to undergo a PG for diagnostic confirmation. Smoothed pacemaker (PM_SAHI) indexes were calculated by averaging the overall number of apnoeas/hypopnoeas over the period between two FU visits, and retrospectively compared with standard PM_AHI. Data were available from 609 consecutive visits (overall 4.64 ± 1.78 years FU). PM_AHI indexes were positive during FU in 40/61 pts (65.6%); 26/40 pts (65%) accepted to undergo a PG recording; Sleep-Lab confirmed positivity in 22/26 pts (84.6% positive predictive value for PM_AHI). A strong correlation (r=0.73) and a high level of concordance were found between smoothed and standard indexes (multivariate analysis, Cohen's-k and Z-score tests). Pacemaker-derived indexes may help in screening paced pts potentially affected by sleep apnoeas. Long-term "smoothed" apnoea indexes could improve the accuracy of pacemaker screening capability, even though this hypothesis must be prospectively confirmed by larger studies. Copyright © 2014 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

Effects of repeated bending load at room temperature for composite Nb3Sn wires

NASA Astrophysics Data System (ADS)

Awaji, Satoshi; Watanabe, Kazuo; Katagiri, Kazumune

2003-09-01

In order to realize a react and wind (R&W) method for Nb3Sn wires, the influences of a bending load at room temperature are investigated. Usually, the superconducting wires undergo bending loads at room temperature repeatedly during winding and insulation processes. We define these bending loads as 'pre-bending' treatments. We applied the pre-bending strain of 0 and 0.5% to the highly strengthened CuNb/(Nb, Ti)3Sn wires, and measured the stress/strain properties and critical currents. The improvements of stress dependence of normalized critical current and the increase of the maximum critical current by the pre-bending treatments were found. The model based on the distribution of the local tensile strain as a bending strain describes the experimental results well without the increase of the maximum critical current. When the pre-bending strain was applied, the calculated results indicate that the mechanical properties are improved due to the local work hardening, and hence the stress dependence of Ic increases.

Pacemakers and implantable cardioverter-defibrillators in pediatric patients.

PubMed

Silka, Michael J; Bar-Cohen, Yaniv

2006-11-01

The use of pacemakers and implantable cardioverter-defibrillators (ICDs) in infants, children, and patients with congenital heart disease presents unique challenges and considerations. They include uncommon indications for device implantation, innovative approaches to lead implantation and configuration, and age-dependent and disease-specific aspects of device programming. In this review, the current indications for pacemaker and ICD implantation in young patients are discussed, followed by consideration of the approaches to lead and device placement in very small patients and those with complex congenital heart disease, in whom unique problems may be encountered. The limitations of programmability of current pacemakers and ICDs when used in young patients are discussed, followed by an analysis of long-term device follow-up and potential late complications.

Direct measurement of the resistivity weighting function

NASA Astrophysics Data System (ADS)

Koon, D. W.; Chan, Winston K.

1998-12-01

We have directly measured the resistivity weighting function—the sensitivity of a four-wire resistance measurement to local variations in resistivity—for a square specimen of photoconducting material. This was achieved by optically perturbing the local resistivity of the specimen while measuring the effect of this perturbation on its four-wire resistance. The weighting function we measure for a square geometry with electrical leads at its corners agrees well with calculated results, displaying two symmetric regions of negative weighting which disappear when van der Pauw averaging is performed.

First principles cable braid electromagnetic penetration model

DOE PAGES

Warne, Larry Kevin; Langston, William L.; Basilio, Lorena I.; ...

2016-01-01

The model for penetration of a wire braid is rigorously formulated. Integral formulas are developed from energy principles for both self and transfer immittances in terms of potentials for the fields. The detailed boundary value problem for the wire braid is also set up in a very efficient manner; the braid wires act as sources for the potentials in the form of a sequence of line multi-poles with unknown coefficients that are determined by means of conditions arising from the wire surface boundary conditions. Approximations are introduced to relate the local properties of the braid wires to a simplified infinitemore » periodic planar geometry. Furthermore, this is used to treat nonuniform coaxial geometries including eccentric interior coaxial arrangements and an exterior ground plane.« less

Heart pacemaker - discharge

MedlinePlus

... table saws) Electric lawnmowers and leaf blowers Slot machines Stereo speakers Tell all providers that you have a pacemaker before any tests are done. Some medical equipment may interfere with ...

Computational analysis of the human sinus node action potential: model development and effects of mutations

PubMed Central

Fabbri, Alan; Fantini, Matteo; Wilders, Ronald

2017-01-01

Key points We constructed a comprehensive mathematical model of the spontaneous electrical activity of a human sinoatrial node (SAN) pacemaker cell, starting from the recent Severi–DiFrancesco model of rabbit SAN cells.Our model is based on electrophysiological data from isolated human SAN pacemaker cells and closely matches the action potentials and calcium transient that were recorded experimentally.Simulated ion channelopathies explain the clinically observed changes in heart rate in corresponding mutation carriers, providing an independent qualitative validation of the model.The model shows that the modulatory role of the ‘funny current’ (I f) in the pacing rate of human SAN pacemaker cells is highly similar to that of rabbit SAN cells, despite its considerably lower amplitude.The model may prove useful in the design of experiments and the development of heart‐rate modulating drugs. Abstract The sinoatrial node (SAN) is the normal pacemaker of the mammalian heart.  Over several decades, a large amount of data on the ionic mechanisms underlying the spontaneous electrical activity of SAN pacemaker cells has been obtained, mostly in experiments on single cells isolated from rabbit SAN. This wealth of data has allowed the development of mathematical models of the electrical activity of rabbit SAN pacemaker cells. The present study aimed to construct a comprehensive model of the electrical activity of a human SAN pacemaker cell using recently obtained electrophysiological data from human SAN pacemaker cells.  We based our model on the recent Severi–DiFrancesco model of a rabbit SAN pacemaker cell. The action potential and calcium transient of the resulting model are close to the experimentally recorded values. The model has a much smaller ‘funny current’ (I f) than do rabbit cells, although its modulatory role is highly similar. Changes in pacing rate upon the implementation of mutations associated with sinus node dysfunction agree with the clinical observations. This agreement holds for both loss‐of‐function and gain‐of‐function mutations in the HCN4, SCN5A and KCNQ1 genes, underlying ion channelopathies in I f, fast sodium current and slow delayed rectifier potassium current, respectively. We conclude that our human SAN cell model can be a useful tool in the design of experiments and the development of drugs that aim to modulate heart rate. PMID:28185290

Clinical and electrophysiological characteristics of patients with paroxysmal intra-His block with narrow QRS complexes.

PubMed

Ragupathi, Loheetha; Johnson, Drew; Greenspon, Arnold; Frisch, Daniel; Ho, Reginald T; Pavri, Behzad B

2018-04-18

Atrioventricular (AV) block is usually due to infranodal disease and associated with a wide QRS complex; such patients often progress to complete AV block and pacemaker dependency. Uncommonly, infranodal AV block can occur within the His bundle with a narrow QRS complex. The aims of this study were to define clinical/echocardiographic characteristics of patients with AV block within the His bundle and report progression to pacemaker dependency. We retrospectively identified patients with narrow QRS complexes and documented intra-His delay or block at electrophysiology study (group A) or with electrocardiogram-documented Mobitz II AV block/paroxysmal AV block (group B). Clinical, electrophysiological, and echocardiographic variables at presentation and pacemaker parameters at the last follow-up visit were evaluated. Twenty-seven patients (19 women) were identified (mean age 64 ± 13 years; range, 38-85 years). Four patients who had <1 month of follow-up were excluded. There were 12 patients in group A and 11 in group B; 21 of 23 presented with syncope/presyncope. All patients received pacemakers: 8 single chamber and 15 dual chamber. After a median follow-up of 6.4 years, the median percentage of ventricular pacing was 1% (interquartile range 0%-4.66%). One patient developed true pacemaker dependency. Aortic and/or mitral annular calcification was present in 13 of 22 patients with available echocardiograms. Patients who present with syncope and narrow QRS complexes with intra-His delay or Mobitz II paroxysmal AV block with narrow QRS complexes rarely progress to pacemaker dependency and require infrequent pacing. This entity is more common in women, with a higher prevalence of aortic and/or mitral annular calcification. If confirmed by additional studies, single-chamber pacemaker may be sufficient. Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Zero-fluoroscopy permanent pacemaker implantation using Ensite NavX system: Clinical viability or fanciful technique?

PubMed

Guo, Ping; Qiu, Jie; Wang, Yan; Chen, Guangzhi; Proietti, Riccardo; Fadhle, Al-Selmi; Zhao, Chunxia; Wen Wang, Dao

2018-02-01

Fluoroscopy is the imaging modality routinely used for cardiac device implantation and electrophysiological procedures. Due to the rising concern regarding the harmful effects of radiation exposure to both the patients and operation staffs, novel 3D mapping systems have been developed and implemented in electrophysiological procedure for the navigation of catheters inside the heart chambers. Their applicability in cardiac device implantation has been rarely reported. Our aim is to evaluate the feasibility and safety of permanent pacemaker implantation without fluoroscopy. From January 2012 to June 2016, six patients (50 ± 15 years, four of six were female, one of who was at the 25th week of gestation) who underwent permanent pacemaker implantation were included (zero-fluoroscopy group). Data from 20 consecutive cases of implantation performed under fluoroscopy guidance were chosen as a control group (fluoroscopy group). Total implantation procedure time for single-chamber pacemaker was 51.3 ± 13.1 minutes in the zero-fluoroscopy group and 42.6 ± 7.4 minutes in the fluoroscopy group (P  =  0.155). The implantation procedural time for a dual-chamber pacemaker was 88.3 ± 19.6 minutes and 67.3 ± 7.6 minutes in the zero-fluoroscopy and fluoroscopy groups (P  =  0.013), respectively. No complications were observed during the procedure and the follow-up in the two groups, and all pacemakers worked with satisfactory parameters. Ensite NavX system can be used as a reliable and safe zero-fluoroscopy approach for the implantation of single- or dual-chamber permanent pacemakers in specific patients, such as pregnant women or in extreme situations when the x-ray machine is not available. © 2017 The Authors. Pacing and Clinical Electrophysiology published by Wiley Periodicals, Inc.

Safety of implantable pacemakers and cardioverter defibrillators in the magnetic field of a novel remote magnetic navigation system.

PubMed

Jilek, Clemens; Tzeis, Stylianos; Reents, Tilko; Estner, Heidi-Luise; Fichtner, Stephanie; Ammar, Sonia; Wu, Jinjin; Hessling, Gabriele; Deisenhofer, Isabel; Kolb, Christof

2010-10-01

Electromagnetic interference with pacemaker and implantable cardioverter defibrillator (ICD) systems may cause temporary or permanent system malfunction of implanted devices. The aim of this study was to evaluate potential interference of a novel magnetic navigation system with implantable rhythm devices. A total of 121 devices (77 pacemakers, 44 ICDs) were exposed to an activated NIOBE II® Magnetic Navigation System (Stereotaxis, St. Louis, MO, USA) at the maximal magnetic field strength of 0.1 Tesla and evaluated in vitro with respect to changes in parameter settings of the device, changes of the battery status/detection of elective replacement indication, or alterations of data stored in the device. A total of 115 out of 121 (95%) devices were free of changes in parameter settings, battery status, and internally stored data after repeated exposition to the electromagnetic field of the remote magnetic navigation system. Interference with the magnetic navigation field was observed in 6 pacemakers, resulting in reprogramming to a power-on-reset mode with or without detection of the elective replacement indication in 5 devices and abnormal variance of battery status in one device. All pacemakers could be reprogrammed to the initial modes and the battery status proved to be normal some minutes after the pacemakers had been removed from the magnetic field. Interference of a remote magnetic navigation system (at maximal field strength) with pacemakers and ICDs not connected to leads with antitachycardic detection and therapies turned off is rare. Occurring functional abnormalities could be reprogrammed in our sample. An in vitro study will give information about interference of devices connected to leads. © 2010 Wiley Periodicals, Inc.

Calsequestrin 2 deletion causes sinoatrial node dysfunction and atrial arrhythmias associated with altered sarcoplasmic reticulum calcium cycling and degenerative fibrosis within the mouse atrial pacemaker complex1

PubMed Central

Glukhov, Alexey V.; Kalyanasundaram, Anuradha; Lou, Qing; Hage, Lori T.; Hansen, Brian J.; Belevych, Andriy E.; Mohler, Peter J.; Knollmann, Björn C.; Periasamy, Muthu; Györke, Sandor; Fedorov, Vadim V.

2015-01-01

Aims Loss-of-function mutations in Calsequestrin 2 (CASQ2) are associated with catecholaminergic polymorphic ventricular tachycardia (CPVT). CPVT patients also exhibit bradycardia and atrial arrhythmias for which the underlying mechanism remains unknown. We aimed to study the sinoatrial node (SAN) dysfunction due to loss of CASQ2. Methods and results In vivo electrocardiogram (ECG) monitoring, in vitro high-resolution optical mapping, confocal imaging of intracellular Ca2+ cycling, and 3D atrial immunohistology were performed in wild-type (WT) and Casq2 null (Casq2−/−) mice. Casq2−/− mice exhibited bradycardia, SAN conduction abnormalities, and beat-to-beat heart rate variability due to enhanced atrial ectopic activity both at baseline and with autonomic stimulation. Loss of CASQ2 increased fibrosis within the pacemaker complex, depressed primary SAN activity, and conduction, but enhanced atrial ectopic activity and atrial fibrillation (AF) associated with macro- and micro-reentry during autonomic stimulation. In SAN myocytes, CASQ2 deficiency induced perturbations in intracellular Ca2+ cycling, including abnormal Ca2+ release, periods of significantly elevated diastolic Ca2+ levels leading to pauses and unstable pacemaker rate. Importantly, Ca2+ cycling dysfunction occurred not only at the SAN cellular level but was also globally manifested as an increased delay between action potential (AP) and Ca2+ transient upstrokes throughout the atrial pacemaker complex. Conclusions Loss of CASQ2 causes abnormal sarcoplasmic reticulum Ca2+ release and selective interstitial fibrosis in the atrial pacemaker complex, which disrupt SAN pacemaking but enhance latent pacemaker activity, create conduction abnormalities and increase susceptibility to AF. These functional and extensive structural alterations could contribute to SAN dysfunction as well as AF in CPVT patients. PMID:24216388

Management and outcome of patients with acute myocardial infarction presenting with pacemaker rhythm.

PubMed

Bertel, Noemi; Witassek, Fabienne; Puhan, Milo; Erne, Paul; Rickli, Hans; Naegeli, Barbara; Pedrazzini, Giovanni; Stauffer, Jean-Christophe; Radovanovic, Dragana

2017-03-01

Diagnosis of acute myocardial infarction (MI) is challenging in pacemaker patients. Little is known about this patient group. Patients with MI enrolled in the Swiss national AMIS Plus registry between January 2005 and December 2015 were analyzed. All patients with either paced ventricular rhythm or sinus rhythm with intrinsic ventricular conduction (IVC) were included in this study. Outcomes using crude data and propensity score matching were compared between patients with pacemaker rhythm and patients with IVC. The primary endpoint was in-hospital death. Data from 300 patients with paced rhythm and 27,595 with IVC were analyzed. Patients with pacemaker rhythm were older (78.2y vs 65.4y; p<0.001), had more comorbidities (Charlson Index (CCI)>1: 54.0% vs 21.1%; p<0.001) and a higher rate of heart failure upon presentation (Killip class>2, 11.0% vs 5.9%; p<0.001) compared to patients with IVC. Door to balloon time in patients undergoing acute PCI is markedly delayed in contrast to patients with IVC (280min vs 85min; p<0.001). Consequently, crude mortality in patients with pacemakers was high (11.3% vs 4.6%; p<0.001). However, when analyzed with propensity matching for gender, age, CCI>1 and Killip>2, mortality was similar (11.2% vs 10.5%; p=0.70). Pacemaker patients with acute MI represent a high-risk group with doubled crude mortality compared to patients without pacemakers, due to higher age and higher Killip class. Diagnosis is difficult and results in delayed treatment. Treatment algorithms for MI with paced rhythm should possibly be adapted to those used for STEMI or new left bundle branch block. NCT01305785. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Global health resource utilization associated with pacemaker complications.

PubMed

Waweru, Catherine; Steenrod, Anna; Wolff, Claudia; Eggington, Simon; Wright, David Jay; Wyrwich, Kathleen W

2017-07-01

To estimate health resource utilization (HRU) associated with the management of pacemaker complications in various healthcare systems. Electrophysiologists (EPs) from four geographical regions (Western Europe, Australia, Japan, and North America) were invited to participate. Survey questions focused on HRU in the management of three chronic pacemaker complications (i.e. pacemaker infections requiring extraction, lead fractures/insulation breaches requiring replacement, and upper extremity deep venous thrombosis [DVT]). Panelists completed a maximum of two web-based surveys (iterative rounds). Mean, median values, and interquartile ranges were calculated and used to establish consensus. Overall, 32 and 29 panelists participated in the first and second rounds of the Delphi panel, respectively. Consensus was reached on treatment and HRU associated with a typical pacemaker implantation and complications. HRU was similar across regions, except for Japan, where panelists reported the longest duration of hospital stay in all scenarios. Infections were the most resource-intensive complications and were characterized by intravenous antibiotics days of 9.6?13.5 days and 21.3?29.2 days for pocket and lead infections respectively; laboratory and diagnostic tests, and system extraction and replacement procedures. DVT, on the other hand, was the least resource intensive complication. The results of the panel represent the views of the respondents who participated and may not be generalizable outside of this panel. The surveys were limited in scope and, therefore, did not include questions on management of acute complications (e.g. hematoma, pneumothorax). The Delphi technique provided a reliable and efficient approach to estimating resource utilization associated with chronic pacemaker complications. Estimates from the Delphi panel can be used to generate costs of pacemaker complications in various regions.

Low permanent pacemaker rates following Lotus device implantation for transcatheter aortic valve replacement due to modified implantation protocol.

PubMed

Krackhardt, Florian; Kherad, Behrouz; Krisper, Maximilian; Pieske, Burkert; Laule, Michael; Tschöpe, Carsten

2017-01-01

Conduction disturbances requiring permanent pacemaker implantation following transcatheter aortic valve replacement (TAVR) are a common problem. Pacemaker implantation rates after TAVR appear to be higher compared to conventional aortic valve replacement. The aim of this study was to analyze whether a high annulus implantation conveys the benefit of a decreased rate of permanent pacemaker implantation while being safe and successful according to Valve Academic Research Consortium 2 (VARC2)-criteria. A total of 23 patients with symptomatic severe aortic valve stenosis, an aortic annulus of 19-27 mm and at high risk for surgery were treated with the Lotus valve. In all patients the valve was implanted in a high annulus position via femoral access. The primary device performance endpoint was VARC2-defined device success after 30 days and the primary safety endpoint was the need for permanent pacemaker implantation. The mean age was 73.23 ± 7.65 years, 46% were female, 38% were New York Heart Association class III/IV at baseline. Thirty-day follow-up data were available for all patients. The VARC2-defined device success rate after 30 days was 22/23 (96%). 2/21 (10%) patients required a newly implanted pacemaker due to 3rd degree atrioventricular block. 25% of the patients developed a new left bundle branch block after valvuloplasty or device implantation. 21 of the 23 patients (96%) had no other signs of conduction disturbances after 30 days. The approach of the modified implantation technique of Lotus TAVR device was safe and effective. The incidence of need for a permanent pacemaker following TAVR could be significantly reduced due to adopted implantation protocol.

Quantum currents and pair correlation of electrons in a chain of localized dots

NASA Astrophysics Data System (ADS)

Morawetz, Klaus

2017-03-01

The quantum transport of electrons in a wire of localized dots by hopping, interaction and dissipation is calculated and a representation by an equivalent RCL circuit is found. The exact solution for the electric-field induced currents allows to discuss the role of virtual currents to decay initial correlations and Bloch oscillations. The dynamical response function in random phase approximation (RPA) is calculated analytically with the help of which the static structure function and pair correlation function are determined. The pair correlation function contains a form factor from the Brillouin zone and a structure factor caused by the localized dots in the wire.

Percutaneous Resection of Renal Urothelial Carcinoma Using Bipolar Electrocautery

PubMed Central

Kwan, Kevin G.; Chew, Ben H.; Luke, Patrick P.W.; Denstedt, John D.

2006-01-01

Percutaneous approaches to upper tract urothelial cancers have been performed in patients unsuitable for radical nephroureterectomy. We present the case of an 82-year-old man with significant comorbidities including dependency on a cardiac pacemaker. Without deactivating the pacemaker, we used bipolar cautery to percutaneously resect a large upper tract urothelial tumor in the renal pelvis. Bipolar cautery is a suitable method of percutaneous or transurethral resection in patients who are pacemaker dependent. PMID:17575777

Development of the cardiac pacemaker

PubMed Central

Liang, Xingqun; Evans, Sylvia M.

2017-01-01

The sinoatrial node (SAN) is the dominant pacemaker of the heart. Abnormalities in SAN formation and function can cause sinus arrhythmia, including sick sinus syndrome and sudden death. A better understanding of genes and signaling pathways that regulate SAN development and function is essential to develop more effective treatment to sinus arrhythmia, including biological pacemakers. In this review, we briefly summarize the key processes of SAN morphogenesis during development, and focus on the transcriptional network that drives SAN development. PMID:27770149

Circadian locomotor rhythms in the cricket, Gryllodes sigillatus. II. Interactions between bilaterally paired circadian pacemakers.

PubMed

Ushirogawa, H; Abe, Y; Tomioka, K

1997-10-01

The optic lobe is essential for circadian locomotor rhythms in the cricket, Gryllodes sigillatus. We examined potential interactions between the bilaterally paired optic lobes in circadian rhythm generation. When one optic lobe was removed, the free-running period of the locomotor rhythm slightly but significantly lengthened. When exposed to light-dark cycles (LD) with 26 hr period, intact and sham operated animals were clearly entrained to the light cycle, but a large number of animals receiving unilateral optic nerve severance showed rhythm dissociation. In the dissociation, two rhythmic components appeared; one was readily entrained to the given LD and the other free-ran with a period shorter than 24 hr, and activity was expressed only when they were inphase. The period of the free-running component was significantly longer than that of the animals with a single blinded pacemaker kept in LD13:13, suggesting that the pacemaker on the intact side had some influence on the blinded pacemaker even in the dissociated state. The ratio of animals with rhythm dissociation was greater with the lower light intensity of the LD. The results suggest that the bilaterally distributed pacemakers are only weakly coupled to one another but strongly suppress the activity driven by the partner pacemaker during their subjective day. The strong suppression of activity would be advantageous to keep a stable nocturnality for this cricket living indoors.

The effect of hyperkalaemia on cardiac rhythm devices.

PubMed

Barold, S Serge; Herweg, Bengt

2014-04-01

In patients with pacemakers, hyperkalaemia causes three important abnormalities that usually become manifest when the K level exceeds 7 mEq/L: (i) widening of the paced QRS complex from delayed intraventricular conduction velocity, (ii) Increased atrial and ventricular pacing thresholds that may cause failure to capture. In this respect, the atria are more susceptible to loss of capture than the ventricles, and (iii) Increased latency (usually with ventricular pacing) manifested by a greater delay of the interval from the pacemaker stimulus to the onset of depolarization. First-degree ventricular pacemaker exit block may progress to second-degree Wenckebach (type I) exit block characterized by gradual prolongation of the interval from the pacemaker stimulus to the onset of the paced QRS complex ultimately resulting in an ineffectual stimulus. The disturbance may then progress to 2 : 1, 3 : 1 pacemaker exit block, etc., and eventually to complete exit block with total lack of capture. Ventricular undersensing is uncommonly observed because of frequent antibradycardia pacing. During managed ventricular pacing, hyperkalaemia-induced marked first-degree atrioventricular block may induce a pacemaker syndrome. With implantable cardioverter-defibrillators (ICDs) oversensing of the paced or spontaneous T-wave may occur. The latter may cause inappropriate shocks. A raised impedance from the right ventricular coil to the superior vena cava coil may become an important sign of hyperkalaemia in the asymptomatic or the minimally symptomatic ICD patient.

Surgical outcome of Fontan conversion and arrhythmia surgery: Need a pacemaker?

PubMed

Terada, Takafumi; Sakurai, Hajime; Nonaka, Toshimichi; Sakurai, Takahisa; Sugiura, Junya; Taneichi, Tetsuyoshi; Ohtsuka, Ryohei

2014-07-01

Atrial tachyarrhythmias are frequent complications in the late period after the Fontan procedure, and important risk factors for a poor prognosis. The impact of Fontan conversion and arrhythmia surgery in failed Fontan patients has been described in many reports. We evaluated our experience with Fontan conversion procedures, concomitant arrhythmia surgery, and pacemaker implantation. We reviewed the hospital records of 25 consecutive patients who underwent a Fontan conversion procedure from January 2004 to March 2012. Twenty-four patients had arrhythmia surgery using cryoablation and radiofrequency ablation at the time of conversion. A bilateral atrial maze procedure was performed in 6 patients, right-side maze in 15, and isthmus block in 3. Three patients with a diagnosis of corrected transposition of the great arteries underwent simultaneous pacemaker implantation electively. There was no early death and one late death during a mean follow-up period of 21.2 months. Three tachyarrhythmia recurrences developed, and there were 4 occurrences of sinus bradycardia. Five of these patients required postoperative pacemaker implantation. The mid-term results of Fontan conversion and arrhythmia surgery in our institute were satisfactory. The occurrence of unexpected postoperative pacemaker requirement was high in the patients who underwent a right atrial or bilateral atrial maze procedure. Pacemaker or lead implantation is recommended for patients planned to undergo a right-side or full maze procedure. © The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Modeling and experimental verification of a fan-folded vibration energy harvester for leadless pacemakers

NASA Astrophysics Data System (ADS)

Ansari, M. H.; Karami, M. Amin

2016-03-01

This paper studies energy harvesting from heartbeat vibrations for powering leadless pacemakers. Unlike traditional pacemakers, leadless pacemakers are implanted inside the heart and the pacemaker is in direct contact with the myocardium. A leadless pacemaker is in the shape of a cylinder. Thus, in order to utilize the available 3-dimensional space for the energy harvester, we choose a fan-folded 3D energy harvester. The proposed device consists of several piezoelectric beams stacked on top of each other. The volume of the energy harvester is 1 cm3 and its dimensions are 2 cm × 0.5 cm × 1 cm. Although high natural frequency is generally a major concern with micro-scale energy harvesters, by utilizing the fan-folded geometry and adding tip mass and link mass to the configuration, we reduced the natural frequency to the desired range. This fan-folded design makes it possible to generate more than 10 μ W of power per cubic centimeter. The proposed device is compatible with Magnetic Resonance Imaging. Although the proposed device is a linear energy harvester, it is relatively insensitive to the heart rate. The natural frequencies and the mode shapes of the device are calculated analytically. The accuracy of the analytical model is verified by experimental investigations. We use a closed loop shaker system to precisely replicate heartbeat vibrations in vitro.

Comparison of DDD versus VVIR pacing modes in elderly patients with atrioventricular block.

PubMed

Kılıçaslan, Barış; Vatansever Ağca, Fahriye; Kılıçaslan, Esin Evren; Kınay, Ozan; Tigen, Kürşat; Cakır, Cayan; Nazlı, Cem; Ergene, Oktay

2012-06-01

Dual-chamber pacing is believed to have an advantage over single-chamber ventricular pacing. The aim of this study was to determine whether elderly patients who have implanted pacemakers for complete atrioventricular block gain significant benefits from dual-chamber (DDD) pacemakers compared with single chamber ventricular (VVIR) pacemakers. This study was designed as a randomized, two-period crossover study-each pacing mode was maintained for 1 month. Thirty patients (16 men, mean age 68.87 ± 6.89 years) with implanted DDD pacemakers were submitted to a standard protocol, which included an interview, pacemaker syndrome assessment, health related quality of life (HRQoL) questionnaires assessed by an SF-36 test, 6-minute walk test (6MWT), and transthoracic echocardiographic examinations. All of these parameters were obtained on both DDD and VVIR mode pacing. Paired data were compared. HRQoL scores were similar, and 6MWT results did not differ between the two groups. VVIR pacing elicited significant enlargement of the left atrium and impaired left ventricular diastolic functions as compared with DDD pacing. Two patients reported subclinical pacemaker syndrome, but this was not statistically significant. Our study revealed that in active elderly patients with complete heart block, DDD pacing and VVIR pacing yielded similar improvements in QoL and exercise performance. However, after a short follow-up period, we noted that VVIR pacing caused significant left atrial enlargement and impaired left ventricular diastolic functions.

Hebbian Wiring Plasticity Generates Efficient Network Structures for Robust Inference with Synaptic Weight Plasticity

PubMed Central

Hiratani, Naoki; Fukai, Tomoki

2016-01-01

In the adult mammalian cortex, a small fraction of spines are created and eliminated every day, and the resultant synaptic connection structure is highly nonrandom, even in local circuits. However, it remains unknown whether a particular synaptic connection structure is functionally advantageous in local circuits, and why creation and elimination of synaptic connections is necessary in addition to rich synaptic weight plasticity. To answer these questions, we studied an inference task model through theoretical and numerical analyses. We demonstrate that a robustly beneficial network structure naturally emerges by combining Hebbian-type synaptic weight plasticity and wiring plasticity. Especially in a sparsely connected network, wiring plasticity achieves reliable computation by enabling efficient information transmission. Furthermore, the proposed rule reproduces experimental observed correlation between spine dynamics and task performance. PMID:27303271

Wiring up pre-characterized single-photon emitters by laser lithography

NASA Astrophysics Data System (ADS)

Shi, Q.; Sontheimer, B.; Nikolay, N.; Schell, A. W.; Fischer, J.; Naber, A.; Benson, O.; Wegener, M.

2016-08-01

Future quantum optical chips will likely be hybrid in nature and include many single-photon emitters, waveguides, filters, as well as single-photon detectors. Here, we introduce a scalable optical localization-selection-lithography procedure for wiring up a large number of single-photon emitters via polymeric photonic wire bonds in three dimensions. First, we localize and characterize nitrogen vacancies in nanodiamonds inside a solid photoresist exhibiting low background fluorescence. Next, without intermediate steps and using the same optical instrument, we perform aligned three-dimensional laser lithography. As a proof of concept, we design, fabricate, and characterize three-dimensional functional waveguide elements on an optical chip. Each element consists of one single-photon emitter centered in a crossed-arc waveguide configuration, allowing for integrated optical excitation and efficient background suppression at the same time.

Efficiency of lithium pacemaker batteries as a function of discharge rate and iodine:P2VP cathode composition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Helgeson, W.D.; Fester, K.E.

1980-01-01

Electrochemical discharge data for Li/I/sub 2/-P2VP pacemaker batteries at various discharge currents show the efficiency of the battery to be a function of discharge current. Depending on the iodine:P2VP cathode composition, the optimum current drain occurs between discharge currents of 100 to 200 /mu/a. As current drain is reduced to pacemaker application drains, 15-25 /mu/a, the efficiency of the Li/I/sub 2/-P2VP battery decreases. The loss in efficiency at pacemaker rates is attributed primarily to self-discharge. The efficiency of Li/I/sub 2/-P2VP batteries is improved by increasing the percent of iodine in the cathode. I/sub 2/:P2VP weight ratios of 10:1, 15:1 andmore » 20:1 have been discharged at various currents and the data indicate that there is significant improvement in efficiency at pacemaker rate in going from 10:1 to 20:1 cathode weight ratio. 2 refs.« less

Mechanisms underlying the cardiac pacemaker: the role of SK4 calcium-activated potassium channels

PubMed Central

Weisbrod, David; Khun, Shiraz Haron; Bueno, Hanna; Peretz, Asher; Attali, Bernard

2016-01-01

The proper expression and function of the cardiac pacemaker is a critical feature of heart physiology. The sinoatrial node (SAN) in human right atrium generates an electrical stimulation approximately 70 times per minute, which propagates from a conductive network to the myocardium leading to chamber contractions during the systoles. Although the SAN and other nodal conductive structures were identified more than a century ago, the mechanisms involved in the generation of cardiac automaticity remain highly debated. In this short review, we survey the current data related to the development of the human cardiac conduction system and the various mechanisms that have been proposed to underlie the pacemaker activity. We also present the human embryonic stem cell-derived cardiomyocyte system, which is used as a model for studying the pacemaker. Finally, we describe our latest characterization of the previously unrecognized role of the SK4 Ca2+-activated K+ channel conductance in pacemaker cells. By exquisitely balancing the inward currents during the diastolic depolarization, the SK4 channels appear to play a crucial role in human cardiac automaticity. PMID:26725737

Mechanisms underlying the cardiac pacemaker: the role of SK4 calcium-activated potassium channels.

PubMed

Weisbrod, David; Khun, Shiraz Haron; Bueno, Hanna; Peretz, Asher; Attali, Bernard

2016-01-01

The proper expression and function of the cardiac pacemaker is a critical feature of heart physiology. The sinoatrial node (SAN) in human right atrium generates an electrical stimulation approximately 70 times per minute, which propagates from a conductive network to the myocardium leading to chamber contractions during the systoles. Although the SAN and other nodal conductive structures were identified more than a century ago, the mechanisms involved in the generation of cardiac automaticity remain highly debated. In this short review, we survey the current data related to the development of the human cardiac conduction system and the various mechanisms that have been proposed to underlie the pacemaker activity. We also present the human embryonic stem cell-derived cardiomyocyte system, which is used as a model for studying the pacemaker. Finally, we describe our latest characterization of the previously unrecognized role of the SK4 Ca(2+)-activated K(+) channel conductance in pacemaker cells. By exquisitely balancing the inward currents during the diastolic depolarization, the SK4 channels appear to play a crucial role in human cardiac automaticity.

Corrosion behavior and surface structure of orthodontic Ni-Ti alloy wires.

PubMed

Iijima, M; Endo, K; Ohno, H; Yonekura, Y; Mizoguchi, I

2001-03-01

The corrosion behaviors of a commercial Ni-Ti alloy orthodontic wire and a polished plate with same composition in 0.9% NaCl and 1% lactic acid solutions were examined using an electrochemical technique, an analysis of released ions, and a surface analysis by X-ray photoelectron spectroscopy (XPS). The effect of polishing the wire on the corrosion was also examined. The XPS analysis demonstrated the presence of a thick oxide film mainly composed of TiO2 with trace amounts of Ni hydroxide, which had formed on the wire surface during the heat treatment and subsequent pickling processes. This oxide layer contributed to the higher resistance of the as-received wire to both general and localized corrosion in 0.9% NaCl solution, compared with that of the polished plate and the polished wire. The thick oxide layer, however, was not stable and did not protect the orthodontic wire from corrosion in 0.1% lactic acid solution.

Bound states and propagating modes in quantum wires with sharp bends and/or constrictions

NASA Astrophysics Data System (ADS)

Razavy, M.

1997-06-01

A number of interesting problems of quantum wires with different geometries can be studied with the help of conformal mapping. These include crossed wires, twisting wires, conductors with constrictions, and wires with a bend. Here the Helmholz equation with Dirichlet boundary condition on the surface of the wire is transformed to a Schröautdinger-like equation with an energy-dependent nonseparable potential but with boundary conditions given on two straight lines. By expanding the wave function in terms of the Fourier series of one of the variables one obtains an infinite set of coupled ordinary differential equations. Only the propagating modes plus a few of the localized modes contribute significantly to the total wave function. Once the problem is solved, one can express the results in terms of the original variables using the inverse conformal mapping. As an example, the total wave function, the components of the current density, and the bound-state energy for a Γ-shaped quantum wire is calculated in detail.

Kirschner wire pin tract infection rates between percutaneous and buried wires in treating metacarpal and phalangeal fractures.

PubMed

Rafique, Atif; Ghani, Shahab; Sadiq, Moiz; Siddiqui, Intisar Ahmed

2006-08-01

To compare pin tract infection rate between percutaneous and buried placement of Kirschner (K-) wiring for hand fractures. Quasi--experimental study. Plastic, Reconstructive, Hand and Burn Surgery Unit, Liaquat National Hospital, Karachi, from September 2005--February 2006. Patients with fractures of metacarpals and phalanges of hand were selected by non-probability purposive method. Assessment of pin tract infection by clinical examination and pin tract scoring was done by modification of Oppenheim classification. Statistical analysis was done using Chi-square test. Ten out of 55 percutaneous and 2 out of 45 buried wires were infected. The difference in infection rates of two groups was statistically significant at p<0.05. Three percutaneous, but not buried Kirschner wires, had to be removed before 4 weeks because of failure to respond to local wound care and oral antibiotics. Percutaneous K- wires had significantly greater infection rate than wires which were buried deep to the skin.

The Modeling of Vibration Damping in SMA Wires

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reynolds, D R; Kloucek, P; Seidman, T I

Through a mathematical and computational model of the physical behavior of shape memory alloy wires, this study shows that localized heating and cooling of such materials provides an effective means of damping vibrational energy. The thermally induced pseudo-elastic behavior of a shape memory wire is modeled using a continuum thermodynamic model and solved computationally as described by the authors in [23]. Computational experiments confirm that up to 80% of an initial shock of vibrational energy can be eliminated at the onset of a thermally-induced phase transformation through the use of spatially-distributed transformation regions along the length of a shape memorymore » alloy wire.« less

Battery Malfunction of a Leadless Cardiac Pacemaker - A Worrisome Single-Center Experience.

PubMed

Richter, Sergio; Döring, Michael; Ebert, Micaela; Bode, Kerstin; Müssigbrodt, Andreas; Sommer, Philipp; Husser, Daniela; Hindricks, Gerhard

2018-03-14

Leadless cardiac pacemaker (LCP) therapy has been established clinically as a feasible and safe alternative to conventional transvenous pacemaker therapy for patients with an indication for single-chamber right-ventricular pacing. 1-3 However, reports on loss of telemetry and pacing output due to abrupt battery failure called the safety of one of the two commercially available systems seriously into question. The initial battery advisory with the Nanostim™ LCP was issued by the manufacturer in October 2016, who instantly called a global stop to Nanostim™ implants. To this day, similar battery issues have not been described for the Micra™ transcatheter pacing system. Therefore, we thought to analyze the long-term pacemaker performance and rate of battery malfunction of the Nanostim™ LCP in our patient population.

Ductal carcinoma of the breast in the pacemaker generator's pocket.

PubMed

Zonca, P; Herokova, J; Cambal, M; Jacobi, C A

2009-01-01

Authors present a case of a 78-year-old female patient with invasive ductal adenocarcinoma in the pacemaker, s pocket. A decubitus-like tumor had developed in this place, and has been missinterpretated as a benign lesion for 5 months. Diagnosis was done with a time delay. An excisional biopsy revealed annvasive ductal adenocarcinoma. The first step was the implantation of a new pacemaker generator performed on the opposite side. The second step was a modified radical mastectomy, according to Madden, and the removal of the originally implanted pacemaker generator. Radiotherapy and hormonal adjuvant therapy were applied after surgery. The patient was followed-up at an out-patient clinic, and died 25 months after diagnosis because of generalization of the disease (Fig. 2, Ref. 35). Full Text (Free, PDF) www.bmj.sk.

Spring Break: A Lesson in Circuits. "This Old House" College Style.

ERIC Educational Resources Information Center

Duch, Barbara

2001-01-01

Introduces students to the topics of electricity and circuits within the context of house wiring. Explores the properties of series and parallel circuits, researches local wiring codes, calculates the current used by appliances based on their power ratings, and designs circuits in a typical kitchen. (Author/ASK)

Breaking wire detection and strain distribution of seven-wire steel cables with acoustic emission and optical fiber sensors.

DOT National Transportation Integrated Search

2013-09-01

Cable-stayed bridges have been increasingly used as river-crossing links in highway and railway transportation networks. In the event : of an abnormal situation, they can not only impact the local and national economy but also threaten the safety of ...

Crystal-Phase Quantum Wires: One-Dimensional Heterostructures with Atomically Flat Interfaces.

PubMed

Corfdir, Pierre; Li, Hong; Marquardt, Oliver; Gao, Guanhui; Molas, Maciej R; Zettler, Johannes K; van Treeck, David; Flissikowski, Timur; Potemski, Marek; Draxl, Claudia; Trampert, Achim; Fernández-Garrido, Sergio; Grahn, Holger T; Brandt, Oliver

2018-01-10

In semiconductor quantum-wire heterostructures, interface roughness leads to exciton localization and to a radiative decay rate much smaller than that expected for structures with flat interfaces. Here, we uncover the electronic and optical properties of the one-dimensional extended defects that form at the intersection between stacking faults and inversion domain boundaries in GaN nanowires. We show that they act as crystal-phase quantum wires, a novel one-dimensional quantum system with atomically flat interfaces. These quantum wires efficiently capture excitons whose radiative decay gives rise to an optical doublet at 3.36 eV at 4.2 K. The binding energy of excitons confined in crystal-phase quantum wires is measured to be more than twice larger than that of the bulk. As a result of their unprecedented interface quality, these crystal-phase quantum wires constitute a model system for the study of one-dimensional excitons.

Effect of load deflection on corrosion behavior of NiTi wire.

PubMed

Liu, I H; Lee, T M; Chang, C Y; Liu, C K

2007-06-01

For dental orthodontic applications, NiTi wires are used under bending conditions in the oral environment for a long period. The purpose of this study was to investigate the effect of bending stress on the corrosion of NiTi wires using potentiodynamic and potentiostatic tests in artificial saliva. The results indicated that bending stress induces a higher corrosion rate of NiTi wires in passive regions. It is suggested that the passive oxide film of specimens would be damaged under bending conditions. Auger electron spectroscopic analysis showed a lower thickness of passive films on stressed NiTi wires compared with unstressed specimens in the passive region. By scanning electron microscopy, localized corrosion was observed on stressed Sentalloy specimens after a potentiodynamic test at pH 2. In conclusion, this study indicated that bending stress changed the corrosion properties and surface characteristics of NiTi wires in a simulated intra-oral environment.

A New Flying Wire System for the Tevatron

NASA Astrophysics Data System (ADS)

Blokland, Willem; Dey, Joseph; Vogel, Greg

1997-05-01

A new Flying Wires system replaces the old system to enhance the analysis of the beam emittance, improve the reliability, and handle the upcoming upgrades of the Tevatron. New VME data acquisition modules and timing modules allow for more bunches to be sampled more precisely. The programming language LabVIEW, running on a Macintosh computer, controls the VME modules and the nuLogic motion board that flies the wires. LabVIEW also analyzes and stores the data, and handles local and remote commands. The new system flies three wires and fits profiles of 72 bunches to a gaussian function within two seconds. A new console application operates the flying wires from any control console. This paper discusses the hardware and software setup, the capabilities and measurement results of the new Flying Wires system.

Extra Luminal Entrapment of Guide Wire; A Rare Complication of Central Venous Catheter Placement in Right Internal Jugular Vein.

PubMed

Ansari, Md Abu Masud; Kumar, Naveen; Kumar, Shailesh; Kumari, Sarita

2016-10-01

Central venous Catheterization (CVC) is a commonly performed procedure for venous access. It is associated with several complications. We report a rare case of extra luminal entrapment of guide wire during CVC placement in right jugular vein. We report a case of 28 years old female patient presented in our emergency with history of entrapped guide wire in right side of neck during CVC. X-ray showed coiling of guide wire in neck. CT Angiography showed guide wire coursing in between common carotid artery and internal jugular vein (IJV), closely abutting the wall of both vessels. The guide wire was coiled with end coursing behind the esophageal wall. Guide wire was removed under fluoroscopic guide manipulation under local anesthesia. We want to emphasize that even though CVC placement is common and simple procedure, serious complication can occur in hands of untrained operator. The procedure should be performed under supervision, if done by trainee. Force should never be applied to advance the guide wire if resistance is encountered.

-X Mixing in T- and V-Shaped Quantum Wires

NASA Astrophysics Data System (ADS)

di Carlo, A.; Pescetelli, S.; Kavokin, A.; Vladimirova, M.; Lugli, P.

1997-11-01

We have applied both tight-binding (TB) and multivalley envelope function (MEF) techniques to calculate the electronic states in T- and V-shaped realistic quantum wires taking into account -X mixing in the conduction band. Strong reduction of the electron quantization energy due to the off-resonant -X mixing has been found in all types of quantum wires. This effect appears to be tied to the localization of the electron wave function and to its overlap with atomic layers next to interfaces.

Effect of non-classical current paths in networks of 1-dimensional wires

NASA Astrophysics Data System (ADS)

Echternach, P. M.; Mikhalchuk, A. G.; Bozler, H. M.; Gershenson, M. E.; Bogdanov, A. L.; Nilsson, B.

1996-04-01

At low temperatures, the quantum corrections to the resistance due to weak localization and electron-electron interaction are affected by the shape and topology of samples. We observed these effects in the resistance of 2D percolation networks made from 1D wires and in a series of long 1D wires with regularly spaced side branches. Branches outside the classical current path strongly reduce the quantum corrections to the resistance and these reductions become a measure of the quantum lengths.

Implantable Medical Devices

MedlinePlus

... Also known as ICD ) - An ICD is a battery-powered device placed under the skin that keeps ... Pacemaker (Also known as Artificial Pacemaker) - A small battery-operated device that helps the heart beat in ...

Engineered Biological Pacemakers | NCI Technology Transfer Center | TTC

Cancer.gov

The National Institute on Aging's Cellular Biophysics Section is seeking statements of capability or interest from parties interested in collaborative research to further develop, evaluate, or commercialize biological pacemakers.

Sick Sinus Syndrome

MedlinePlus

... rhythm problems (arrhythmias) in which the heart's natural pacemaker (sinus node) doesn't work properly. The sinus ... people with sick sinus syndrome eventually need a pacemaker to keep the heart in a regular rhythm. ...

Sick sinus syndrome

MedlinePlus

... the heart (atria). This area is the heart's pacemaker. It may be called the sinoatrial node, sinus ... do so. You may need a permanent implanted pacemaker if your symptoms are related to bradycardia (slow ...

Impact of imaging landmark on the risk of MRI-related heating near implanted medical devices like cardiac pacemaker leads.

PubMed

Nordbeck, Peter; Ritter, Oliver; Weiss, Ingo; Warmuth, Marcus; Gensler, Daniel; Burkard, Natalie; Herold, Volker; Jakob, Peter M; Ertl, Georg; Ladd, Mark E; Quick, Harald H; Bauer, Wolfgang R

2011-01-01

Implanted medical devices such as cardiac pacemakers pose a potential hazard in magnetic resonance imaging. Electromagnetic fields have been shown to cause severe radio frequency-induced tissue heating in some cases. Imaging exclusion zones have been proposed as an instrument to reduce patient risk. The purpose of this study was to further assess the impact of the imaging landmark on the risk for unintended implant heating by measuring the radio frequency-induced electric fields in a body phantom under several imaging conditions at 1.5T. The results show that global radio frequency-induced coupling is highest with the torso centered along the superior-inferior direction of the transmit coil. The induced E-fields inside the body shift when changing body positioning, reducing both global and local radio frequency coupling if body and/or conductive implant are moved out from the transmit coil center along the z-direction. Adequate selection of magnetic resonance imaging landmark can significantly reduce potential hazards in patients with implanted medical devices. © 2010 Wiley-Liss, Inc.

Fatigue failure of regenerator screens in a high frequency Stirling engine

NASA Technical Reports Server (NTRS)

Hull, David R.; Alger, Donald L.; Moore, Thomas J.; Scheuermann, Coulson M.

1988-01-01

Failure of Stirling Space Power Demonstrator Engine (SPDE) regenerator screens was investigated. After several hours of operation the SPDE was shut down for inspection and on removing the regenator screens, debris of unknown origin was discovered along with considerable cracking of the screens in localized areas. Metallurgical analysis of the debris determined it to be cracked-off-deformed pieces of the 41 micron thickness Type 304 stainless steel wire screen. Scanning electron microscopy of the cracked screens revealed failures occurring at wire crossovers and fatigue striations on the fracture surface of the wires. Thus, the screen failure can be characterized as a fatigue failure of the wires. The crossovers were determined to contain 30 percent reduction in wire thickness and a highly worked microstructure occurring from the manufacturing process of the wire screens. Later it was found that reduction in wire thickness occurred because the screen fabricator had subjected it to a light cold-roll process after weaving. Installation of this screen left a clearance in the regenerator allowing the screens to move. The combined effects of the reduction in wire thickness, stress concentration (caused by screen movement), and highly worked microstructure at the wire crossovers led to the fatigue failure of the screens.

Complete removal of infected devices and simultaneous implantation of new devices for infective endocarditis after pacemaker implantation.

PubMed

Miura, Takuya; Inoue, Kazushige; Yokota, Takenori; Iwata, Takashi; Yoshitatsu, Masao

2017-02-01

Two cases of infective endocarditis after pacemaker implantation were reported. Complete removal of infected devices was performed under cardiopulmonary bypass, and simultaneous implantation of new devices was performed using epicardial leads and generator on the abdominal wall. The postoperative course was uneventful and recurrence was not recognized. These procedures may be suitable for the patients who depend on the pacemaker or who have repeat bacteremia with other infectious disease or conditions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Warne, Larry K.; Langston, William L.; Basilio, Lorena I.

The model for penetration of a wire braid is rigorously formulated. Integral formulas are developed from energy principles and reciprocity for both self and transfer immittances in terms of potentials for the fields. The detailed boundary value problem for the wire braid is also setup in a very efficient manner; the braid wires act as sources for the potentials in the form of a sequence of line multipoles with unknown coefficients that are determined by means of conditions arising from the wire surface boundary conditions. Approximations are introduced to relate the local properties of the braid wires to a simplifiedmore » infinite periodic planar geometry. This is used in a simplified application of reciprocity to be able to treat nonuniform coaxial geometries including eccentric interior coaxial arrangements and an exterior ground plane.« less

The chopstick-noodle twist: an easy technique of percutaneous patellar fixation in minimally displaced patellar fractures.

PubMed

Muzaffar, Nasir; Ahmad, Nawaz; Ahmad, Aejaz; Ahmad, Nissar

2012-01-01

We report six cases of minimally displaced two-part patellar fractures with skin injury over the patella that were treated with percutaneous K wire fixation and compression applied using stainless steel (SS) wire. This technique makes it possible to perform early operative treatment in cases where unhealthy skin is not amenable to conventional tension band wiring. The technique employs two K wires inserted through the two fracture fragments under local or regional anaesthesia. They are then compressed using simple SS wire knots at the two ends - making it look like noodles at the end of two chopsticks. The fixation is subsequently augmented with a cylindrical plaster-of-Paris cast. The technique is simple, cheap and does not cause soft tissue injury.

Pacemaker

MedlinePlus

... check for changes in your heart's electrical activity. Battery Replacement Pacemaker batteries last between 5 and 15 years (average 6 ... doctor will replace the generator along with the battery before the battery starts to run down. Replacing ...

Implantable cardioverter defibrillator - discharge

MedlinePlus

... defibrillation. This device can also work as a pacemaker. What to Expect at Home When you leave ... pubmed/23265327 . Swerdlow CD, Wang PL, Zipes DP. Pacemakers and implantable cardioverter-defibrillators. In: Mann DL, Zipes ...

Localized etching of an insulator film coated on a copper wire using an atmospheric-pressure microplasma jet.

PubMed

Yoshiki, Hiroyuki

2007-04-01

Atmospheric-pressure microplasma jets (APmicroPJs) of Ar and ArO(2) gases were generated from the tip of a stainless steel surgical needle having outer and inner diameters of 0.4 and 0.2 mm, respectively, with a rf excitation of 13.56 MHz. The steel needle functions both as a powered electrode and a gas nozzle. The operating power is 1.2-6 W and the corresponding peak-to-peak voltage Vp.p. is about 1.5 kV. The APmicroPJ was applied to the localized etching of a polyamide-imide insulator film (thickness of 10 microm) of a copper winding wire of 90 microm diameter. The insulator film around the copper wire was completely removed by the irradiated plasma from a certain direction without fusing the wire. The removal time under the Ar APmicroPJ irradiation was only 3 s at a rf power of 4 W. Fluorescence microscopy and scanning electron microscope images reveal that good selectivity of the insulator film to the copper wire was achieved. In the case of ArO(2) APmicroPJ irradiation with an O(2) concentration of 10% or more, the removed copper surface was converted to copper monoxide CuO.

Treatment of carcinoma of the penis by iridium 192 wire implant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daly, N.J.; Douchez, J.; Combes, P.F.

1982-07-01

Since 1971, a group of 22 adult patients with squamous cell carcinoma of the penis have been treated by iridium 192 wire implants. There were 6 T1 tumors, 14 T2 tumors and 2 T3; only one patient (T3) presented with local failure after implant. Local necrosis occurred in 2 patients without local tumoral recurrence, but was sufficient enough to warrant amputation. Thus 19/22 (86%) patients were locally cured with penile conservation. In these patients the most frequent posttherapeutic complication is chronic urethral stenosis (9/19 patients, 47%) requiring repeated instrumental dilations. Four patients presented with initial inguinal mestastatic nodes; only onemore » was cured by radiosurgical treatment. Among patients without metastatic nodes at the time of diagnosis, none had delayed metastatic nodes. Three patients died of nodal evolution, 5 patients died of intercurrent disease without evidence of disease and 14 are now alive and NED. It appears that iridium 192 wire implant is the most effective conservative treatment of invasive squamous cell carcinoma of the penis; however, these results confirm that no particular treatment is required for inguinal nodal areas for patients who initially present with no disease.« less

Prevention and Treatment of Arrhythmia

MedlinePlus

... your pulse – especially if you have an artificial pacemaker. Put the second and third fingers of one ... Ablation Devices for Arrhythmia - Implantable Cardioverter Defibrillator (ICD) - Pacemaker Treating Arrhythmias in Children • Arrhythmia Tools & Resources Watch, ...

[Hyperkalemia-induced failure of pacemaker capture and sensing: a case report].

PubMed

Wang, Y P; Chen, B X; Su, K J; Sun, L J; Zhang, Y; Guo, L J; Gao, W

2014-12-18

Hyperkalemia may induce serious cardiac arrhythmia, with possible life-threatening effects. It may cause cardiac pacemaker (PMK) malfunctioning due to a reduction of the electronegativity of the resting myocardial potential. We report the case of a 71-year-old woman who had a previous history of chronic heart failure, chronic renal failure and DDI pacemaker. She was admitted for disturbance of consciousness. During hospitalization, she was observed for extreme hypotension, acute hyperkalemia, ventricular escape rhythm, associated with failure of pacemaker capture and sensing. She was treated with calcium chloride injection, followed by insulin/glucose and sodium bicarbonate infusions; the electrocardiogram recordings showed an correction of the PMK malfunctioning and serial improvement of the intraventricular conduction. This case supports that hyperkalemia should be closely monitored in the chronic heart failure patients combined with chronic renal failure.

Signaling of Pigment-Dispersing Factor (PDF) in the Madeira Cockroach Rhyparobia maderae

PubMed Central

Funk, Nico W.; Giese, Maria; Baz, El-Sayed; Stengl, Monika

2014-01-01

The insect neuropeptide pigment-dispersing factor (PDF) is a functional ortholog of vasoactive intestinal polypeptide, the coupling factor of the mammalian circadian pacemaker. Despite of PDF's importance for synchronized circadian locomotor activity rhythms its signaling is not well understood. We studied PDF signaling in primary cell cultures of the accessory medulla, the circadian pacemaker of the Madeira cockroach. In Ca2+ imaging studies four types of PDF-responses were distinguished. In regularly bursting type 1 pacemakers PDF application resulted in dose-dependent long-lasting increases in Ca2+ baseline concentration and frequency of oscillating Ca2+ transients. Adenylyl cyclase antagonists prevented PDF-responses in type 1 cells, indicating that PDF signaled via elevation of intracellular cAMP levels. In contrast, in type 2 pacemakers PDF transiently raised intracellular Ca2+ levels even after blocking adenylyl cyclase activity. In patch clamp experiments the previously characterized types 1–4 could not be identified. Instead, PDF-responses were categorized according to ion channels affected. Application of PDF inhibited outward potassium or inward sodium currents, sometimes in the same neuron. In a comparison of Ca2+ imaging and patch clamp experiments we hypothesized that in type 1 cells PDF-dependent rises in cAMP concentrations block primarily outward K+ currents. Possibly, this PDF-dependent depolarization underlies PDF-dependent phase advances of pacemakers. Finally, we propose that PDF-dependent concomitant modulation of K+ and Na+ channels in coupled pacemakers causes ultradian membrane potential oscillations as prerequisite to efficient synchronization via resonance. PMID:25269074

Minimally Invasive Epicardial Pacemaker Implantation in Neonates with Congenital Heart Block.

PubMed

Costa, Roberto; Silva, Katia Regina da; Martinelli Filho, Martino; Carrillo, Roger

2017-10-01

Few studies have characterized the surgical outcomes following epicardial pacemaker implantation in neonates with congenital complete atrioventricular block (CCAVB). This study sought to assess the long-term outcomes of a minimally invasive epicardial approach using a subxiphoid access for pacemaker implantation in neonates. Between July 2002 and February 2015, 16 consecutive neonates underwent epicardial pacemaker implantation due to CCAVB. Among these, 12 (75.0%) had congenital heart defects associated with CCAVB. The patients had a mean age of 4.7 ± 5.3 days and nine (56.3%) were female. Bipolar steroid-eluting epicardial leads were implanted in all patients through a minimally invasive subxiphoid approach and fixed on the diaphragmatic ventricular surface. The pulse generator was placed in an epigastric submuscular position. All procedures were successful, with no perioperative complications or early deaths. Mean operating time was 90.2 ± 16.8 minutes. None of the patients displayed pacing or sensing dysfunction, and all parameters remained stable throughout the follow-up period of 4.1 ± 3.9 years. Three children underwent pulse generator replacement due to normal battery depletion at 4.0, 7.2, and 9.0 years of age without the need of ventricular lead replacement. There were two deaths at 12 and 325 days after pacemaker implantation due to bleeding from thrombolytic use and progressive refractory heart failure, respectively. Epicardial pacemaker implantation through a subxiphoid approach in neonates with CCAVB is technically feasible and associated with excellent surgical outcomes and pacing lead longevity.

Outcomes of cardiac pacing in adult patients after a Fontan operation.

PubMed

Egbe, Alexander C; Huntley, Geoffery D; Connolly, Heidi M; Ammash, Naser M; Deshmukh, Abhishek J; Khan, Arooj R; Said, Sameh M; Akintoye, Emmanuel; Warnes, Carole A; Kapa, Suraj

2017-12-01

Cardiac pacing can be challenging after a Fontan operation, and limited data exist regarding pacing in adult Fontan patients. The objectives of our study were to determine risk factors for pacing and occurrence of device-related complications (DRCs) and pacemaker reinterventions. We performed a retrospective review of Fontan patients from 1994 through 2014. We defined DRCs as lead failure, lead recall, cardiac perforation, lead thrombus/vegetation, or device-related infection, and cardiovascular adverse events (CAEs) as venous thrombosis, stroke, death, or heart transplant. Pacemaker reintervention was defined as lead failure or recall. Of 439 patients, 166 (38%) had pacemakers implanted (79 during childhood; 87, adulthood); 114 patients (69%) received epicardial leads initially, and 52 (31%), endocardial leads. Pacing was initially atrial in 52 patients (31%); ventricular, 30 (18%); or dual chamber, 84 (51%). There were 37 reinterventions (1.9% per year) and 48 DRCs (2.4% per year). Pacemaker implantation during childhood was a risk factor for DRCs (hazard ratio, 2.01 [CI, 1.22-5.63]; P = .03). There were 70 CAEs (venous thrombosis, 5; stroke, 11; transplant, 8; and death, 46), yielding a rate of 3.5% per year. DRCs, CAEs, and reintervention rates were comparable for patients with epicardial or endocardial leads. More than one-third of adult Fontan patients referred to Mayo Clinic had pacemaker implantation. Epicardial leads were associated with high rate of pacemaker reinterventions but similar DRC rates in comparison to endocardial leads. Copyright © 2017 Elsevier Inc. All rights reserved.

Recovery of Ventriculo-Atrial Conduction after Adrenaline in Patients Implanted with Pacemakers.

PubMed

Cismaru, Gabriel; Gusetu, Gabriel; Muresan, Lucian; Rosu, Radu; Andronache, Marius; Matuz, Roxana; Puiu, Mihai; Mester, Petru; Miclaus, Maria; Pop, Dana; Mircea, Petru Adrian; Zdrenghea, Dumitru

2015-07-01

Ventriculo-atrial (VA) conduction can have negative consequences for patients with implanted pacemakers and defibrillators. There is concern whether impaired VA conduction could recover during stressful situations. Although the influence of isoproterenol and atropine are well established, the effect of adrenaline has not been studied systematically. The objective of this study was to determine if adrenaline can facilitate recovery of VA conduction in patients implanted with pacemakers. A prospective study was conducted on 61 consecutive patients during a 4-month period (April-July 2014). The presence of VA conduction was assessed during the pacemaker implantation procedure. In case of an impaired VA conduction, adrenaline infusio was used as a stress surrogate to test conduction recovery. The indications for pacemaker implantation were: sinus node dysfunction in 18 patients, atrioventricular (AV) block in 40 patients, binodal dysfunction (sinus node+ AV node) in two patients and other (carotid sinus syndrome) in one patient. In the basal state, 15/61 (24.6%) presented spontaneous VA conduction and 46/61 (75.4%) had no VA conduction. After administration of adrenaline, there was VA conduction recovery in 5/46 (10.9%) patients. Adrenaline infusion produced recovery of VA conduction in 10.9% of patients with absent VA conduction in a basal state. Recovery of VA conduction during physiological or pathological stresses could be responsible for the pacemaker syndrome, PMT episodes, or certain implantable cardiac defibrillator detection issues. © 2015 Wiley Periodicals, Inc.

Effect of sheath material and reaction overpressure on Ag protrusions into the TiO2 insulation coating of Bi-2212 round wire

NASA Astrophysics Data System (ADS)

Hossain, I.; Jiang, J.; Matras, M.; Trociewitz, U. P.; Lu, J.; Kametani, F.; Larbalestier, D.; Hellstrom, E.

2017-12-01

In order to develop a high current density in coils, Bi-2212 wires must be electrically discrete in tight winding packs. It is vital to use an insulating layer that is thin, fulfils the dielectric requirements, and can survive the heat treatment whose maximum temperature reaches 890 °C in oxygen. A thin (20-30 µm) ceramic coating could be better as the insulating layer compared to alumino-silicate braided fiber insulation, which is about 150 μm thick and reacts with the Ag sheathed Bi-2212 wire during heat treatment. At present, TiO2 seems to be the most viable ceramic material for such a thin insulation because it is chemically compatible with Ag and Bi-2212 and its sintering temperature is lower than the maximum temperature used for the Bi-2212 heat treatment. However, recent tests of a large Bi-2212 coil insulated only with TiO2 showed severe electrical shorting between the wires after over pressure heat treatment (OPHT). The origin of the shorting was frequent silver protrusions into the porous TiO2 layer that electrically connected adjacent Bi-2212 wires. To understand the mechanism of this unexpected behaviour, we investigated the effect of sheath material and hydrostatic pressure on Ag protrusions. We found that Ag protrusions occur only when TiO2-insulated Ag-0.2%Mg sheathed wire (Ag(Mg) wire) undergoes OPHT at 50 bar. No Ag protrusions were observed when the TiO2-insulated Ag(Mg) wire was processed at 1 bar. The TiO2-insulated wires sheathed with pure Ag that underwent 50 bar OPHT were also free from Ag protrusions. A key finding is that the Ag protrusions from the Ag(Mg) sheath actually contain no MgO, suggesting that local depletion of MgO facilitates local, heterogeneous deformation of the sheath under hydrostatic overpressure. Our study also suggests that predensifying the Ag(Mg) wire before insulating it with TiO2 and doing the final OPHT can potentially limit Ag protrusions.

Thermal Hydraulic Computational Fluid Dynamics Simulations and Experimental Investigation of Deformed Fuel Assemblies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mays, Brian; Jackson, R. Brian

2017-03-08

The project, Toward a Longer Life Core: Thermal Hydraulic CFD Simulations and Experimental Investigation of Deformed Fuel Assemblies, DOE Project code DE-NE0008321, was a verification and validation project for flow and heat transfer through wire wrapped simulated liquid metal fuel assemblies that included both experiments and computational fluid dynamics simulations of those experiments. This project was a two year collaboration between AREVA, TerraPower, Argonne National Laboratory and Texas A&M University. Experiments were performed by AREVA and Texas A&M University. Numerical simulations of these experiments were performed by TerraPower and Argonne National Lab. Project management was performed by AREVA Federal Services.more » The first of a kind project resulted in the production of both local point temperature measurements and local flow mixing experiment data paired with numerical simulation benchmarking of the experiments. The project experiments included the largest wire-wrapped pin assembly Mass Index of Refraction (MIR) experiment in the world, the first known wire-wrapped assembly experiment with deformed duct geometries and the largest numerical simulations ever produced for wire-wrapped bundles.« less

Fluorescence circadian imaging reveals a PDF-dependent transcriptional regulation of the Drosophila molecular clock.

PubMed

Sabado, Virginie; Vienne, Ludovic; Nunes, José Manuel; Rosbash, Michael; Nagoshi, Emi

2017-01-30

Circadian locomotor behaviour is controlled by a pacemaker circuit composed of clock-containing neurons. To interrogate the mechanistic relationship between the molecular clockwork and network communication critical to the operation of the Drosophila circadian pacemaker circuit, we established new fluorescent circadian reporters that permit single-cell recording of transcriptional and post-transcriptional rhythms in brain explants and cultured neurons. Live-imaging experiments combined with pharmacological and genetic manipulations demonstrate that the neuropeptide pigment-dispersing factor (PDF) amplifies the molecular rhythms via time-of-day- and activity-dependent upregulation of transcription from E-box-containing clock gene promoters within key pacemaker neurons. The effect of PDF on clock gene transcription and the known role of PDF in enhancing PER/TIM stability occur via independent pathways downstream of the PDF receptor, the former through a cAMP-independent mechanism and the latter through a cAMP-PKA dependent mechanism. These results confirm and extend the mechanistic understanding of the role of PDF in controlling the synchrony of the pacemaker neurons. More broadly, our results establish the utility of the new live-imaging tools for the study of molecular-neural interactions important for the operation of the circadian pacemaker circuit.

Fluorescence circadian imaging reveals a PDF-dependent transcriptional regulation of the Drosophila molecular clock

PubMed Central

Sabado, Virginie; Vienne, Ludovic; Nunes, José Manuel; Rosbash, Michael; Nagoshi, Emi

2017-01-01

Circadian locomotor behaviour is controlled by a pacemaker circuit composed of clock-containing neurons. To interrogate the mechanistic relationship between the molecular clockwork and network communication critical to the operation of the Drosophila circadian pacemaker circuit, we established new fluorescent circadian reporters that permit single-cell recording of transcriptional and post-transcriptional rhythms in brain explants and cultured neurons. Live-imaging experiments combined with pharmacological and genetic manipulations demonstrate that the neuropeptide pigment-dispersing factor (PDF) amplifies the molecular rhythms via time-of-day- and activity-dependent upregulation of transcription from E-box-containing clock gene promoters within key pacemaker neurons. The effect of PDF on clock gene transcription and the known role of PDF in enhancing PER/TIM stability occur via independent pathways downstream of the PDF receptor, the former through a cAMP-independent mechanism and the latter through a cAMP-PKA dependent mechanism. These results confirm and extend the mechanistic understanding of the role of PDF in controlling the synchrony of the pacemaker neurons. More broadly, our results establish the utility of the new live-imaging tools for the study of molecular-neural interactions important for the operation of the circadian pacemaker circuit. PMID:28134281

Pheochromocytoma-Induced Atrial Tachycardia Leading to Cardiogenic Shock and Cardiac Arrest: Resolution with Atrioventricular Node Ablation and Pacemaker Placement

PubMed Central

Bajaj, Mandeep; Cunningham, Glenn R.

2014-01-01

Pheochromocytoma should be considered in young patients who have acute cardiac decompensation, even if they have no history of hypertension. Atrioventricular node ablation and pacemaker placement should be considered for stabilizing pheochromocytoma patients with cardiogenic shock due to atrial tachyarrhythmias. A 38-year-old black woman presented with cardiogenic shock (left ventricular ejection fraction, <0.15) that did not respond to the placement of an intra-aortic balloon pump. A TandemHeart® Percutaneous Ventricular Assist Device was inserted emergently. After atrioventricular node ablation and placement of a temporary pacemaker, the TandemHeart was removed. Computed tomography of the abdomen revealed a pheochromocytoma. After placement of a permanent pacemaker, the patient underwent a right adrenalectomy. This is, to our knowledge, the first reported case of pheochromocytoma-induced atrial tachyarrhythmia that led to cardiogenic shock and cardiac arrest unresolved by the placement of 2 different ventricular assist devices, but that was completely reversed by radiofrequency ablation of the atrioventricular node and the placement of a temporary pacemaker. We present the patient's clinical, laboratory, and imaging findings, and we review the relevant literature. PMID:25593537

Effect of 1. 5 tesla nuclear magnetic resonance imaging scanner on implanted permanent pacemakers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayes, D.L.; Holmes, D.R. Jr.; Gray, J.E.

1987-10-01

Patients with a permanent pacemaker are currently restricted from diagnostic nuclear magnetic resonance (NMR) imaging because of potential adverse effects on the pacemaker by the magnet. Previous work has shown that NMR imaging will result in asynchronous pacing of the pulse generator within a given distance of the magnet. The radiofrequency signal generated by the system may also result in rapid cardiac pacing, which may have deleterious effects. This study utilized a 1.5 tesla unit in an in vivo laboratory animal to evaluate the unit's effects on eight different pulse generators from two manufacturers. All pacemakers functioned in an asynchronousmore » mode when placed within a certain distance of the magnet. In addition, transient reed switch inhibition was observed. Seven of the eight pulse generators paced rapidly when exposed to the radiofrequency signal and there was a dramatic decrease in arterial blood pressure. Whether effective rapid cardiac pacing would occur could not be predicted before exposure to the magnetic resonance unit. Nuclear magnetic resonance imaging with high magnetic fields in patients with a pacemaker should continue to be avoided until the mechanism of the rapid cardiac pacing can be further delineated and either predicted or prevented.« less

Optimal Pulse Configuration Design for Heart Stimulation. A Theoretical, Numerical and Experimental Study.

NASA Astrophysics Data System (ADS)

Hardy, Neil; Dvir, Hila; Fenton, Flavio

Existing pacemakers consider the rectangular pulse to be the optimal form of stimulation current. However, other waveforms for the use of pacemakers could save energy while still stimulating the heart. We aim to find the optimal waveform for pacemaker use, and to offer a theoretical explanation for its advantage. Since the pacemaker battery is a charge source, here we probe the stimulation current waveforms with respect to the total charge delivery. In this talk we present theoretical analysis and numerical simulations of myocyte ion-channel currents acting as an additional source of charge that adds to the external stimulating charge for stimulation purposes. Therefore, we find that as the action potential emerges, the external stimulating current can be reduced accordingly exponentially. We then performed experimental studies in rabbit and cat hearts and showed that indeed exponential truncated pulses with less total charge can still induce activation in the heart. From the experiments, we present curves showing the savings in charge as a function of exponential waveform and we calculated that the longevity of the pacemaker battery would be ten times higher for the exponential current compared to the rectangular waveforms. Thanks to Petit Undergraduate Research Scholars Program and NSF# 1413037.

Case studies on the effect of exercise and hot water submersion on intracardiac temperature and the performance of a pacemaker which varies pacing rate based on temperature.

PubMed

Fearnot, N E; Kitoh, O; Fujita, T; Okamura, H; Smith, H J; Calderini, M

1989-05-01

The effectiveness of using blood temperature change as an indicator to automatically vary heart rate physiologically was evaluated in 3 patients implanted with Model Sensor Kelvin 500 (Cook Pacemaker Corporation, Leechburg, PA, USA) pacemakers. Each patient performed two block-randomized treadmill exercise tests: one while programmed for temperature-based, rate-modulated pacing and the other while programmed without rate modulation. In 1 pacemaker patient and 4 volunteers, heart rates were recorded during exposure to a hot water bath. Blood temperature measured at 10 sec intervals and pacing rate measured at 1 min intervals were telemetered to a diagnostic programmer and data collector for storage and transfer to a computer. Observation comments and ECG-derived heart rates were manually recorded. The temperature-based pacemaker was shown to respond promptly not only to physical exertion but also to emotionally caused stress and submersion in a hot bath. These events cause increased heart rate in the normal heart. Using a suitable algorithm to process the measurement of blood temperature, it was possible to produce appropriate pacing rates in paced patients.

Decreased human circadian pacemaker influence after 100 days in space: a case study

NASA Technical Reports Server (NTRS)

Monk, T. H.; Kennedy, K. S.; Rose, L. R.; Linenger, J. M.

2001-01-01

OBJECTIVE: The objectives of this study were (1) to assess the circadian rhythms and sleep of a healthy, 42-year-old male astronaut experiencing microgravity (weightlessness) for nearly 5 months while living aboard Space Station Mir as it orbited Earth and (2) to determine the effects of prolonged space flight on the endogenous circadian pacemaker, as indicated by oral temperature and subjective alertness rhythms, and their ramifications for sleep, alertness, and performance. METHODS: For three 12- to 14-day blocks of time (spread throughout the mission), oral temperatures were taken and subjective alertness was self-rated five times per day. Sleep diaries and performance tests were also completed daily during each block. RESULTS: Examination of the subject's circadian alertness and oral temperature rhythms suggested that the endogenous circadian pacemaker seemed to function quite well up to 90 days in space. Thereafter (on days 110-122), the influence of the endogenous circadian pacemaker on oral temperature and subjective alertness circadian rhythms was considerably weakened, with consequent disruptions in sleep. CONCLUSIONS: Space missions lasting more than 3 months might result in diminished circadian pacemaker influence in astronauts, leading to eventual sleep problems.

Pacemakers and Implantable Defibrillators: MedlinePlus Health Topic

MedlinePlus

... pattern. Most arrhythmias result from problems in the electrical system of the heart. If your arrhythmia is ... pacemaker helps control abnormal heart rhythms. It uses electrical pulses to prompt the heart to beat at ...

42 CFR 410.10 - Medical and other health services: Included services.

Code of Federal Regulations, 2013 CFR

2013-10-01

... vaccinations. (m) Outpatient physical therapy and speech pathology services. (n) Cardiac pacemakers and pacemaker leads. (o) Additional services furnished to enrollees of HMOs or CMPs, as described in § 410.58...

42 CFR 410.10 - Medical and other health services: Included services.

Code of Federal Regulations, 2014 CFR

2014-10-01

... vaccinations. (m) Outpatient physical therapy and speech pathology services. (n) Cardiac pacemakers and pacemaker leads. (o) Additional services furnished to enrollees of HMOs or CMPs, as described in § 410.58...

42 CFR 410.10 - Medical and other health services: Included services.

Code of Federal Regulations, 2012 CFR

2012-10-01

... vaccinations. (m) Outpatient physical therapy and speech pathology services. (n) Cardiac pacemakers and pacemaker leads. (o) Additional services furnished to enrollees of HMOs or CMPs, as described in § 410.58...

Length-Dependent Nanotransport and Charge Hopping Bottlenecks in Long Thiophene-Containing π-Conjugated Molecular Wires.

PubMed

Smith, Christopher E; Odoh, Samuel O; Ghosh, Soumen; Gagliardi, Laura; Cramer, Christopher J; Frisbie, C Daniel

2015-12-23

Self-assembled conjugated molecular wires containing thiophene up to 6 nm in length were grown layer-by-layer using click chemistry. Reflection-absorption infrared spectroscopy, ellipsometry and X-ray photoelectron spectroscopy were used to follow the stepwise growth. The electronic structure of the conjugated wires was studied with cyclic voltammetry and UV-vis spectroscopy as well as computationally with density functional theory (DFT). The current-voltage curves (±1 V) of the conjugated molecular wires were measured with conducting probe atomic force microscopy (CP-AFM) in which the molecular wire film bound to a gold substrate was contacted with a conductive AFM probe. By systematically measuring the low bias junction resistance as a function of length for molecules 1-4 nm long, we extracted the structure dependent tunneling attenuation factor (β) of 3.4 nm(-1) and a contact resistance of 220 kΩ. The crossover from tunneling to hopping transport was observed at a molecular length of 4-5 nm with an activation energy of 0.35 eV extracted from Arrhenius plots of resistance versus temperature. DFT calculations revealed localizations of spin densities (polarons) on molecular wire radical cations. The calculations were employed to gauge transition state energies for hopping of polarons along wire segments. Individual estimated transition state energies were 0.2-0.4 eV, in good agreement with the experimental activation energy. The transition states correspond to flattening of dihedral angles about specific imine bonds. These results open up possibilities to further explore the influence of molecular architecture on hopping transport in molecular junctions, and highlight the utility of DFT to understand charge localization and associated hopping-based transport.

Bridge cable fracture detection with acoustic emission test (Conference Presentation)

NASA Astrophysics Data System (ADS)

Qu, Hongya; Li, Tiantian; Chen, Genda

2017-04-01

In this study, acoustic emission (AE) tests were conducted to detect and locate wire fracture in strands that are widely used in cable-stayed and suspension bridges. To effectively separate fracture signals from unwanted noises, distinct features of fracture, fracture-induced echo, and artificial tapping signals as well as their dependence on loading levels are characterized with short-time Fourier transform. To associate fracture scenarios with their acoustic features, two 20-foot-long ( 6.1 m) 270 ksi ( 1,862 MPa) steel strands of seven wires were tested with one wire notched off at center and support, respectively, up to 90% of its cross section area by 10% increment. Up to 80% reduction in cross section area of the notched wire, each strand was loaded to 20 kips ( 89 kN) corresponding to 35% of the minimum breaking strength and the acquired AE parameters such as hits, energy, and counts were found to change little. With a reduction of 90% of the section area of one wire, both strands were found to be fractured under approximately 16.5 kips ( 73.4 kN). The hits, energy, and counts of AE signals were all demonstrated to suddenly change with the fracture of the notched wire. However, only the counts of AE signals distributed over the length of the strands allow the localization of fracture point. The frequency band of fracture signals is significantly broader than that of either fracture-induced echo or artificial tapping noise. The time duration of artificial tapping noises is substantially longer than that of either fracture or fracture-induced echo. These distinct characteristics can be used to effectively separate fracture signals from noises for wire fracture detection and localization in practice.

Mechanisms of resistance change under pressure for AgNP-based conducting wires

NASA Astrophysics Data System (ADS)

Qian, Zhentao; Liu, Liping; Huang, Han; Cheng, Xiong; Zhu, Xiaobo; Gu, Wenhua

2018-02-01

The silver nanoparticle (AgNP) based conducting wire is a fundamental element of flexible electronic devices, especially in the printing electronics area. Its resistance change mechanisms under pressure is of both scientific interest and practical importance. AgNP-based conducting wires were fabricated on flexible substrates by electrospraying printing technology, and three possible resistance change mechanisms were studied: vertical deformation (VD) of the AgNP wire due to vertical pressure, horizontal wire elongation (HWE) along with the flexible substrate due to vertical pressure, and local micro deformation (LMD) at the touching edge. Analysis of the experiment data revealed that the resistance change due to VD was negligible, the resistance change due to PWE was one order of magnitude smaller than the measured value, and the resistance change due to PWE was the dominating mechanism.

Induced Pluripotent Stem Cell–Derived Cardiomyocytes Provide In Vivo Biological Pacemaker Function

PubMed Central

Chauveau, Samuel; Anyukhovsky, Evgeny P.; Ben-Ari, Meital; Naor, Shulamit; Jiang, Ya-Ping; Danilo, Peter; Rahim, Tania; Burke, Stephanie; Qiu, Xiaoliang; Potapova, Irina A.; Doronin, Sergey V.; Brink, Peter R.; Binah, Ofer

2017-01-01

Background— Although multiple approaches have been used to create biological pacemakers in animal models, induced pluripotent stem cell–derived cardiomyocytes (iPSC-CMs) have not been investigated for this purpose. We now report pacemaker function of iPSC-CMs in a canine model. Methods and Results— Embryoid bodies were derived from human keratinocytes, their action potential characteristics determined, and their gene expression profiles and markers of differentiation identified. Atrioventricular blocked dogs were immunosuppressed, instrumented with VVI pacemakers, and injected subepicardially into the anterobasal left ventricle with 40 to 75 rhythmically contracting embryoid bodies (totaling 1.3–2×106 cells). ECG and 24-hour Holter monitoring were performed biweekly. After 4 to 13 weeks, epinephrine (1 μg kg−1 min−1) was infused, and the heart removed for histological or electrophysiological study. iPSC-CMs largely lost the markers of pluripotency, became positive for cardiac-specific markers. and manifested If-dependent automaticity. Epicardial pacing of the injection site identified matching beats arising from that site by week 1 after implantation. By week 4, 20% of beats were electronically paced, 60% to 80% of beats were matching, and mean and maximal biological pacemaker rates were 45 and 75 beats per minute. Maximum night and day rates of matching beats were 53±6.9 and 69±10.4 beats per minute, respectively, at 4 weeks. Epinephrine increased rate of matching beats from 35±4.3 to 65±4.0 beats per minute. Incubation of embryoid bodies with the vital dye, Dil, revealed the persistence of injected cells at the site of administration. Conclusions— iPSC-CMs can integrate into host myocardium and create a biological pacemaker. Although this is a promising development, rate and rhythm of the iPSC-CMs pacemakers remain to be optimized. PMID:28500172

DOE Office of Scientific and Technical Information (OSTI.GOV)

James, J; Place, V; Panda, A

Purpose: Several institutions have developed MRI guidelines for patients with MR-unsafe or MR-conditional pacemakers. Here we highlight the role of a medical physicist in implementing these guidelines for non-pacemaker dependent patients. Guidelines: Implementing these guidelines requires involvement from several medical specialties and a strong collaboration with the site MRI supervisor to develop a structured workflow. A medical physicist is required to be present during the scan to supervise the MR scanning and to maintain a safety checklist that ensures: 1) uninterrupted patient communication with the technologist, 2) continuous patient physiologic monitoring (e.g. blood pressure and electrocardiography) by a trained nurse,more » 3) redundant patient vitals monitoring (e.g. pulse oximetry) due to the possibility of in vivo electrocardiography reading fluctuations during image acquisition. A radiologist is strongly recommended to be available to review the images before patients are discharged from the scanner. Pacemaker MRI should be restricted to 1.5T field strength. The MRI sequences should be optimized by the physicist with regards to: a) SAR: limited to <1.5 W/Kg for MR-unsafe pacemakers in normal operating mode, b) RF exposure time: <30 min, c) Coils: use T/R coils but not restricted to such, d) Artifacts: further optimization of sequences whenever image quality is compromised due to the pacemaker. In particular, cardiac, breast and left-shoulder MRIs are most susceptible to these artifacts. Possible strategies to lower the SAR include: a) BW reduction, 2) echo-train-length reduction, 3) increase TR, 4) decrease number of averages, 5) decrease flip angle, 6) reduce slices and/or a combination of all the options. Conclusion: A medical physicist in collaboration with the MR supervisor plays an important role in the supervision/implementation of safe MR scanning of pacemaker patients. Developing and establishing a workflow has enabled our institution to scan over 30 patients with pacemakers without complications, including 3 cardiac MR exams.« less

Pacemaker replacement in nonagenarians: Procedural safety and long-term follow-up.

PubMed

Loirat, Aurélie; Fénéon, Damien; Behaghel, Albin; Behar, Nathalie; Le Helloco, Alain; Mabo, Philippe; Daubert, Jean-Claude; Leclercq, Christophe; Martins, Raphaël P

2015-01-01

The rate of pacemaker implantation is rising. Given that the life expectancy of the population is projected to increase, a large number of elderly patients are likely to be implanted in the future. As pacemaker batteries can last for 8-10years, an increasing number of pacemaker recipients will require replacement of their devices when they become nonagenarians. To analyse the short- and long-term outcomes after device replacement in nonagenarians. Patients aged≥90years referred to a tertiary centre for pacemaker replacement from January 2004 to July 2014 were included retrospectively. Clinical follow-up data were obtained from clinical visits or telephone interviews with patients or their families. The primary clinical endpoint was total mortality. Secondary endpoints included early and delayed procedure-related complications and predictive risk factors for total mortality. Sixty-two patients were included (mean age 93.3±2.9years at time of pacemaker replacement). Mean procedure duration was 35.7±17.2minutes. Mean hospital stay was 2.2±1.1days. One patient died from a perioperative complication. Thirty-seven patients (59.7%) died during a median follow-up of 22.1months (interquartile range, 11.8-39.8months). Survival rates were 84.2% (95% confidence interval [CI] 71.8-91.5%) at 1year, 66.9% (95% CI 51.8-78.2%) at 2years and 22.7% (95% CI 10.6-37.7%) at 5years. Atrial fibrillation (hazard ratio 2.47, 95% CI 1.1-5.6) and non-physiological pacing (i.e. VVI pacing in patients in sinus rhythm) (hazard ratio 2.20, 95% CI 1.0-4.9) were predictors of mortality. Pacemaker replacement in nonagenarians is a safe and straightforward procedure. These data suggest that procedures can be performed securely in this old and frail population, with patients living for a median of 30months afterwards. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Runtime Verification of Pacemaker Functionality Using Hierarchical Fuzzy Colored Petri-nets.

PubMed

Majma, Negar; Babamir, Seyed Morteza; Monadjemi, Amirhassan

2017-02-01

Today, implanted medical devices are increasingly used for many patients and in case of diverse health problems. However, several runtime problems and errors are reported by the relevant organizations, even resulting in patient death. One of those devices is the pacemaker. The pacemaker is a device helping the patient to regulate the heartbeat by connecting to the cardiac vessels. This device is directed by its software, so any failure in this software causes a serious malfunction. Therefore, this study aims to a better way to monitor the device's software behavior to decrease the failure risk. Accordingly, we supervise the runtime function and status of the software. The software verification means examining limitations and needs of the system users by the system running software. In this paper, a method to verify the pacemaker software, based on the fuzzy function of the device, is presented. So, the function limitations of the device are identified and presented as fuzzy rules and then the device is verified based on the hierarchical Fuzzy Colored Petri-net (FCPN), which is formed considering the software limits. Regarding the experiences of using: 1) Fuzzy Petri-nets (FPN) to verify insulin pumps, 2) Colored Petri-nets (CPN) to verify the pacemaker and 3) To verify the pacemaker by a software agent with Petri-network based knowledge, which we gained during the previous studies, the runtime behavior of the pacemaker software is examined by HFCPN, in this paper. This is considered a developing step compared to the earlier work. HFCPN in this paper, compared to the FPN and CPN used in our previous studies reduces the complexity. By presenting the Petri-net (PN) in a hierarchical form, the verification runtime, decreased as 90.61% compared to the verification runtime in the earlier work. Since we need an inference engine in the runtime verification, we used the HFCPN to enhance the performance of the inference engine.

Right bundle branch block without overt heart disease predicts higher risk of pacemaker implantation: the study of atomic-bomb survivors.

PubMed

Kusumoto, Saburo; Kawano, Hiroaki; Makita, Naomasa; Ichimaru, Shinichiro; Kaku, Takashi; Haruta, Daisuke; Hida, Ayumi; Sera, Nobuko; Imaizumi, Misa; Nakashima, Eiji; Maemura, Koji; Akahoshi, Masazumi

2014-06-01

We investigated the clinical course of complete right bundle branch block (RBBB) or RBBB with axis deviation (AD) in terms of subsequent pacemaker implantation for high-degree atrioventricular (AV) block or sick sinus syndrome (SSS). Among the 16,170 atomic-bomb survivors in our biennial health examination between July 1967 and December 2010, we detected 520 newly-acquired RBBB subjects with no organic heart disease, and selected 1038 age- (at RBBB diagnosis) and sex-matched subjects without RBBB to serve as comparison subjects. Multivariate Cox regression analysis was used to estimate the hazard ratios (HRs) for the risk of pacemaker implantation due to all causes, AV block or SSS between RBBB and comparison subjects and between RBBB subjects with and without AD. The risk of pacemaker implantation for RBBB was 4.79 (95% confidence interval [CI] 1.89-12.58; P=0.001), 3.77 (95% CI, 1.09-13.07; P=0.036), and 6.28 (95% CI, 1.24-31.73, P=0.026) when implantation was for all causes, AV block and SSS, respectively. RBBB subjects with AD had a higher risk for all-cause pacemaker implantation than subjects without AD (HR, 3.03; 95% CI, 1.00-9.13, P=0.049). RBBB subjects with AD were younger than subjects without AD at the time of RBBB diagnosis (59.4±7.6 vs 74.4±3.1 years old, P=0.019), and their progression from diagnosis to pacemaker implantation took longer (15.1±6.6 vs 6.4±3.0 years, P=0.032). RBBB, especially with AD, progresses to AV block and SSS that requires pacemaker implantation; the mechanisms by which the conduction defect progresses differ among patients with and without AD. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Surface characteristics and damage distributions of diamond wire sawn wafers for silicon solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sopori, Bhushan; Devayajanam, Srinivas; Basnyat, Prakash

2016-01-01

This paper describes surface characteristics, in terms of its morphology, roughness and near-surface damage of Si wafers cut by diamond wire sawing (DWS) of Si ingots under different cutting conditions. Diamond wire sawn Si wafers exhibit nearly-periodic surface features of different spatial wavelengths, which correspond to kinematics of various movements during wafering, such as ingot feed, wire reciprocation, and wire snap. The surface damage occurs in the form of frozen-in dislocations, phase changes, and microcracks. The in-depth damage was determined by conventional methods such as TEM, SEM and angle-polishing/defect-etching. However, because these methods only provide local information, we have alsomore » applied a new technique that determines average damage depth over a large area. This technique uses sequential measurement of the minority carrier lifetime after etching thin layers from the surfaces. The lateral spatial damage variations, which seem to be mainly related to wire reciprocation process, were observed by photoluminescence and minority carrier lifetime mapping. Our results show a strong correlation of damage depth on the diamond grit size and wire usage.« less

Mapping the Galvanic Corrosion of Three Metals Coupled with a Wire Beam Electrode: The Influence of Temperature and Relative Geometrical Position.

PubMed

Ju, Hong; Yang, Yuan-Feng; Liu, Yun-Fei; Liu, Shu-Fa; Duan, Jin-Zhuo; Li, Yan

2018-02-28

The local electrochemical properties of galvanic corrosion for three coupled metals in a desalination plant were investigated with three wire-beam electrodes as wire sensors: aluminum brass (HAl77-2), titanium (TA2), and 316L stainless steel (316L SS). These electrodes were used with artificial seawater at different temperatures. The potential and current-density distributions of the three-metal coupled system are inhomogeneous. The HAl77-2 wire anodes were corroded in the three-metal coupled system. The TA2 wires acted as cathodes and were protected; the 316L SS wires acted as secondary cathodes. The temperature and electrode arrangement have important effects on the galvanic corrosion of the three-metal coupled system. The corrosion current of the HAl77-2 increased with temperature indicating enhanced anode corrosion at higher temperature. In addition, the corrosion of HAl77-2 was more significant when the HAl77-2 wires were located in the middle of the coupled system than with the other two metal arrangement styles.

Mapping the Galvanic Corrosion of Three Metals Coupled with a Wire Beam Electrode: The Influence of Temperature and Relative Geometrical Position

PubMed Central

Liu, Yun-Fei; Liu, Shu-Fa; Duan, Jin-Zhuo

2018-01-01

The local electrochemical properties of galvanic corrosion for three coupled metals in a desalination plant were investigated with three wire-beam electrodes as wire sensors: aluminum brass (HAl77-2), titanium (TA2), and 316L stainless steel (316L SS). These electrodes were used with artificial seawater at different temperatures. The potential and current–density distributions of the three-metal coupled system are inhomogeneous. The HAl77-2 wire anodes were corroded in the three-metal coupled system. The TA2 wires acted as cathodes and were protected; the 316L SS wires acted as secondary cathodes. The temperature and electrode arrangement have important effects on the galvanic corrosion of the three-metal coupled system. The corrosion current of the HAl77-2 increased with temperature indicating enhanced anode corrosion at higher temperature. In addition, the corrosion of HAl77-2 was more significant when the HAl77-2 wires were located in the middle of the coupled system than with the other two metal arrangement styles. PMID:29495617

Electrophoretic-like gating used to control metal-insulator transitions in electronically phase separated manganite wires.

PubMed

Guo, Hangwen; Noh, Joo H; Dong, Shuai; Rack, Philip D; Gai, Zheng; Xu, Xiaoshan; Dagotto, Elbio; Shen, Jian; Ward, T Zac

2013-08-14

Electronically phase separated manganite wires are found to exhibit controllable metal-insulator transitions under local electric fields. The switching characteristics are shown to be fully reversible, polarity independent, and highly resistant to thermal breakdown caused by repeated cycling. It is further demonstrated that multiple discrete resistive states can be accessed in a single wire. The results conform to a phenomenological model in which the inherent nanoscale insulating and metallic domains are rearranged through electrophoretic-like processes to open and close percolation channels.

First-principles Theory of Inelastic Transport and Local Heating in Atomic Gold Wires

NASA Astrophysics Data System (ADS)

Frederiksen, Thomas; Paulsson, Magnus; Brandbyge, Mads; Jauho, Antti-Pekka

2007-04-01

We present theoretical calculations of the inelastic transport properties in atomic gold wires. Our method is based on a combination of density functional theory and non-equilibrium Green's functions. The vibrational spectra for extensive series of wire geometries have been calculated using SIESTA, and the corresponding effects in the conductance are analyzed. In particular, we focus on the heating of the active vibrational modes. By a detailed comparison with experiments we are able to estimate an order of magnitude for the external damping of the active vibrations.

A Parametric Computational Model of the Action Potential of Pacemaker Cells.

PubMed

Ai, Weiwei; Patel, Nitish D; Roop, Partha S; Malik, Avinash; Andalam, Sidharta; Yip, Eugene; Allen, Nathan; Trew, Mark L

2018-01-01

A flexible, efficient, and verifiable pacemaker cell model is essential to the design of real-time virtual hearts that can be used for closed-loop validation of cardiac devices. A new parametric model of pacemaker action potential is developed to address this need. The action potential phases are modeled using hybrid automaton with one piecewise-linear continuous variable. The model can capture rate-dependent dynamics, such as action potential duration restitution, conduction velocity restitution, and overdrive suppression by incorporating nonlinear update functions. Simulated dynamics of the model compared well with previous models and clinical data. The results show that the parametric model can reproduce the electrophysiological dynamics of a variety of pacemaker cells, such as sinoatrial node, atrioventricular node, and the His-Purkinje system, under varying cardiac conditions. This is an important contribution toward closed-loop validation of cardiac devices using real-time heart models.

The dynamics of GABA signaling: Revelations from the circadian pacemaker in the suprachiasmatic nucleus

PubMed Central

Albers, H. Elliott; Walton, James C.; Gamble, Karen L.; McNeill, John K.; Hummer, Daniel L.

2016-01-01

Virtually every neuron within the suprachiasmatic nucleus (SCN) communicates via GABAergic signaling. The extracellular levels of GABA within the SCN are determined by a complex interaction of synthesis and transport, as well as synaptic and non-synaptic release. The response to GABA is mediated by GABAA receptors that respond to both phasic and tonic GABA release and that can produce excitatory as well as inhibitory cellular responses. GABA also influences circadian control through the exclusively inhibitory effects of GABAB receptors. Both GABA and neuropeptide signaling occur within the SCN, although the functional consequences of the interactions of these signals are not well understood. This review considers the role of GABA in the circadian pacemaker, in the mechanisms responsible for the generation of circadian rhythms, in the ability of non-photic stimuli to reset the phase of the pacemaker, and in the ability of the day-night cycle to entrain the pacemaker. PMID:27894927

The ethics of deactivating a pacemaker in a pacing-dependent patient: reflections on a case study.

PubMed

Malpas, Phillipa J; Cooper, Lisa

2012-11-01

The decision to deactivate a pacemaker in a pacing-dependent patient is troubling for some health professionals who may regard such interventions as hastening death and therefore ethically impermissible. This may be especially concerning in situations where a patient is unable to clearly state what their preferences may be and the decision--were it to be made--will almost certainly result in the patient's immediate death. In this discussion, we reflect on some of the ethical aspects that arise when JP, a 75-year-old woman who is pacing dependent, suffers a significant brain injury, and the family request that her pacemaker be deactivated. Taking into account the clinical reality of her situation, the united wishes and loving concern of her husband and family, and their substituted judgment regarding her likely preferences, we claim that the decision to deactivate her pacemaker was ethically sound.

Fifty years of pacemaker advancements.

PubMed

Steinhaus, David

2008-12-01

A 1957 power blackout in Minnesota prompted C. Walton Lillehei, MD, a pioneer in open heart surgery, to ask Earl Bakken, the co-founder of Medtronic, Inc., to create a battery-operated pacemaker for pediatric patients. That conversation led to the development of the first external battery-operated pacemaker. That first bulky device is far removed from the tiny implantable computers available to heart patients today. Now, the size of two silver dollars stacked on top of one another, a pacemaker is prescribed for a person whose heart beats too slowly or pauses irregularly. Slightly larger devices have more recently evolved from pacing and regulating the heartbeat to being able to provide therapeutic high voltage shocks when needed to stop runaway fast heart rates, recording heart activity, and other physiologic functions, even resynchronizing the heart's chambers-all while providing information on the patient's condition and device performance to the doctor remotely or in the office.

The influence of anatomical and physiological parameters on the interference voltage at the input of unipolar cardiac pacemakers in low frequency electric fields.

PubMed

Joosten, S; Pammler, K; Silny, J

2009-02-07

The problem of electromagnetic interference of electronic implants such as cardiac pacemakers has been well known for many years. An increasing number of field sources in everyday life and occupational environment leads unavoidably to an increased risk for patients with electronic implants. However, no obligatory national or international safety regulations exist for the protection of this patient group. The aim of this study is to find out the anatomical and physiological worst-case conditions for patients with an implanted pacemaker adjusted to unipolar sensing in external time-varying electric fields. The results of this study with 15 volunteers show that, in electric fields, variation of the interference voltage at the input of a cardiac pacemaker adds up to 200% only because of individual factors. These factors should be considered in human studies and in the setting of safety regulations.

[The computer assisted pacemaker clinic at the regional hospital of Udine (author's transl)].

PubMed

Feruglio, G A; Lestuzzi, L; Carminati, D

1978-01-01

For a close follow-up of large groups of pacemaker patients and for evaluation of long term pacing on a reliable statistical basis, many pacemaker centers in the world are now using computer systems. A patient data system with structured display records, designed to give complete, comprehensive and surveyable information and which are immediately retrievable 24 hours a day, on display or printed sets, seems to offer an ideal solution. The pacemaker clinic at the Regional Hospital of Udine has adopted this type of system. The clinic in linked to a live, on-line patient data system (G/3, Informatica Friuli-Venezia Giulia). The input and retrieval of information are made through a conventional keyboard. The input formats have fixed headings with coded alternatives and a limited space for comments in free text. The computer edits the coded information to surveyable reviews. Searches can be made on coded information and data of interest.

A Full-Visible-Spectrum Invisibility Cloak for Mesoscopic Metal Wires.

PubMed

Kim, Sang-Woo; An, Byeong Wan; Cho, Eunjin; Hyun, Byung Gwan; Moon, Yoon-Jong; Kim, Sun-Kyung; Park, Jang-Ung

2018-06-13

Structured metals can sustain a very large scattering cross-section that is induced by localized surface plasmons, which often has an adverse effect on their use as transparent electrodes in displays, touch screens, and smart windows due to an issue of low clarity. Here, we report a broadband optical cloaking strategy for the network of mesoscopic metal wires with submicrometer to micrometer diameters, which is exploited for manufacturing and application of high-clarity metal-wires-based transparent electrodes. We prepare electrospun Ag wires with 300-1800 nm in diameter and perform a facile surface oxidation process to form Ag/Ag 2 O core/shell heterogeneous structures. The absorptive Ag 2 O shell, together with the coating of a dielectric cover, leads to the cancellation of electric multipole moments in Ag wires, thereby drastically suppressing plasmon-mediated scattering over the full visible spectrum and rendering Ag wires to be invisible. Simultaneously with the effect of invisibility, the transmittance of Ag/Ag 2 O wires is significantly improved compared to bare Ag wires, despite the formation of an absorptive Ag 2 O shell. As an application example, we demonstrate that these invisible Ag wires serve as a high-clarity, high-transmittance, and high-speed defroster for automotive windshields.

Fatigue failure of regenerator screens in a high frequency Stirling engine

NASA Technical Reports Server (NTRS)

Hull, David R.; Alger, Donald L.; Moore, Thomas J.; Scheuermann, Coulson M.

1987-01-01

Failure of Stirling Space Power Demonstrator Engine (SPDE) regenerator screens was investigated. After several hours of operation the SPDE was shut down for inspection and on removing the regenerator screens, debris of unknown origin was discovered along with considerable cracking of the screens in localized areas. Metallurgical analysis of the debris determined it to be cracked-off-deformed pieces of the 41 micron thickness Type 304 stainless steel wire screen. Scanning electron microscopy of the cracked screens revealed failures occurring at wire crossovers and fatigue striations on the fracture surface of the wires. Thus, the screen failure can be characterized as a fatigue failure of the wires. The crossovers were determined to contain a 30 percent reduction in wire thickness and a highly worked microstructure occurring from the manufacturing process of the wire screens. Later it was found that reduction in wire thickness occurred because the screen fabricator had subjected it to a light cold-roll process after weaving. Installation of this screen left a clearance in the regenerator allowing the screens to move. The combined effects of the reduction in wire thickness, stress concentration (caused by screen movement), and highly worked microstructure at the wire crossovers led to the fatigue failure of the screens.

Comparison of X-ray Radiation Process in Single and Nested Wire Array Implosions

NASA Astrophysics Data System (ADS)

Li, Z. H.; Xu, Z. P.; Yang, J. L.; Xu, R. K.; Guo, C.; Grabovsky, E. V.; Oleynic, G. M.; Smirnov, V. P.

2006-01-01

In order to understanding the difference between tungsten single-wire-array and tungsten nested-wire-array Z-pinches, we have measured the x-ray power, the temporal-spatial distributions of x-ray radiation from each of the two loads. The measurements were performed with 0.1mm spatial and 1 ns temporal resolutions at 2.5- and 3.5-MA currents. The experimental conditions, including wire material, number of wires, wire-array length, electrode design, and implosion time, remained unchanged from shot to shot. Analysis of the radiation power profiles suggests that the nested-wire-array radiate slightly less x-ray energy in relatively shorter time interval than the single wire-array, leading to a much greater x-ray power in nested-wire-array implosion. The temporal-spatial distributions of x-ray power show that in both cases, plasmas formed by wire-array ablation radiate not simultaneously along load axis. For nested-wire-array Z-pinch, plasmas near the anode begin to radiate in 2ns later than that near the cathode. As a contrast, the temporal divergence of radiation among different plasma zones of single-wire-array Z-pinch along Z-axis is more than 6ns. Measurements of the x-ray emissions from small segments of pinch (2mm length along axis) indicate that local radiation power profiles almost do not vary for the two loads. Photographs taken by X-ray framing camera give a same description about the radiation process of pinch. One may expect that, as a result of this study, if the single-wire-array can be redesigned so ingeniously that the x-rays are emitted at the same time all over the pinch zone, the radiation power of single wire array Z-pinch may be much greater than what have been achieved.

Hopkins installs wire harnesses

NASA Image and Video Library

2013-11-24

ISS038-E-008291 (24 Nov. 2013) --- NASA astronaut Michael Hopkins, Expedition 38 flight engineer, installs wire harnesses in the International Space Station?s Harmony node to support the installation of Ethernet video cables for the station?s local area network. These new cables will provide Ethernet connectivity to the visiting vehicles that dock to Harmony?s Earth-facing port.

Signaling of pigment-dispersing factor (PDF) in the Madeira cockroach Rhyparobia maderae.

PubMed

Wei, Hongying; Yasar, Hanzey; Funk, Nico W; Giese, Maria; Baz, El-Sayed; Stengl, Monika

2014-01-01

The insect neuropeptide pigment-dispersing factor (PDF) is a functional ortholog of vasoactive intestinal polypeptide, the coupling factor of the mammalian circadian pacemaker. Despite of PDF's importance for synchronized circadian locomotor activity rhythms its signaling is not well understood. We studied PDF signaling in primary cell cultures of the accessory medulla, the circadian pacemaker of the Madeira cockroach. In Ca²⁺ imaging studies four types of PDF-responses were distinguished. In regularly bursting type 1 pacemakers PDF application resulted in dose-dependent long-lasting increases in Ca²⁺ baseline concentration and frequency of oscillating Ca²⁺ transients. Adenylyl cyclase antagonists prevented PDF-responses in type 1 cells, indicating that PDF signaled via elevation of intracellular cAMP levels. In contrast, in type 2 pacemakers PDF transiently raised intracellular Ca²⁺ levels even after blocking adenylyl cyclase activity. In patch clamp experiments the previously characterized types 1-4 could not be identified. Instead, PDF-responses were categorized according to ion channels affected. Application of PDF inhibited outward potassium or inward sodium currents, sometimes in the same neuron. In a comparison of Ca²⁺ imaging and patch clamp experiments we hypothesized that in type 1 cells PDF-dependent rises in cAMP concentrations block primarily outward K⁺ currents. Possibly, this PDF-dependent depolarization underlies PDF-dependent phase advances of pacemakers. Finally, we propose that PDF-dependent concomitant modulation of K⁺ and Na⁺ channels in coupled pacemakers causes ultradian membrane potential oscillations as prerequisite to efficient synchronization via resonance.

Mechanism underlying impaired cardiac pacemaking rhythm during ischemia: A simulation study

NASA Astrophysics Data System (ADS)

Bai, Xiangyun; Wang, Kuanquan; Yuan, Yongfeng; Li, Qince; Dobrzynski, Halina; Boyett, Mark R.; Hancox, Jules C.; Zhang, Henggui

2017-09-01

Ischemia in the heart impairs function of the cardiac pacemaker, the sinoatrial node (SAN). However, the ionic mechanisms underlying the ischemia-induced dysfunction of the SAN remain elusive. In order to investigate the ionic mechanisms by which ischemia causes SAN dysfunction, action potential models of rabbit SAN and atrial cells were modified to incorporate extant experimental data of ischemia-induced changes to membrane ion channels and intracellular ion homeostasis. The cell models were incorporated into an anatomically detailed 2D model of the intact SAN-atrium. Using the multi-scale models, the functional impact of ischemia-induced electrical alterations on cardiac pacemaking action potentials (APs) and their conduction was investigated. The effects of vagal tone activity on the regulation of cardiac pacemaker activity in control and ischemic conditions were also investigated. The simulation results showed that at the cellular level ischemia slowed the SAN pacemaking rate, which was mainly attributable to the altered Na+-Ca2+ exchange current and the ATP-sensitive potassium current. In the 2D SAN-atrium tissue model, ischemia slowed down both the pacemaking rate and the conduction velocity of APs into the surrounding atrial tissue. Simulated vagal nerve activity, including the actions of acetylcholine in the model, amplified the effects of ischemia, leading to possible SAN arrest and/or conduction exit block, which are major features of the sick sinus syndrome. In conclusion, this study provides novel insights into understanding the mechanisms by which ischemia alters SAN function, identifying specific conductances as contributors to bradycardia and conduction block.

Ten-year Survival and Its Associated Factors in the Patients Undergoing Pacemaker Implantation in Hospitals Affiliated to Shiraz University of Medical Sciences During 2002 - 2012

PubMed Central

Rajaeefard, Abdolreza; Ghorbani, Mohammad; Babaee Baigi, Mohammad Ali; Tabatabae, Hamidreza

2015-01-01

Background: Heart failure is a prevalent disease affecting about 4.9 million people in the U.S. and more than 22 million individuals worldwide. Using electric pacemaker is the most common treatment for the patients with heart conduction problems. The present study aimed to determine the factors affecting survival in the patients undergoing pacemaker implantation in the hospitals affiliated to Shiraz University of Medical Sciences. Objectives: The aim of the present study was to identify the factors affecting the survival of the patients suffering from arrhythmia. Patients and Methods: This retrospective survival analysis was conducted on all 1207 patients with heart failure who had undergone permanent pacemaker implantation in the hospitals affiliated to Shiraz University of Medical Sciences from 2002 to 2012. The data were analyzed using non-parametric methods such as Kaplan-Meier method, life table, and Cox regression model. The risk factors of mortality were determined using multivariate Cox proportional hazards method. Results: Survival data were available for 1030 (80%) patients (median age = 71 years [5th to 95th percentile range: 26 - 86 years]) and follow-up was completed for 84.28% of them. According to the results, 56% of the patients had received dual-chamber systems, while 44% had been implanted by single-chamber ventricular systems. Moreover, sick sinus syndrome and pacemaker mode were independent predictors of increased mortality. Conclusions: In this study, sick sinus syndrome and pacemaker mode followed by syncope were independently associated with increased mortality. PMID:26734484

Incidence of Bradycardia and Outcomes of Patients Who Underwent Orbital Atherectomy Without a Temporary Pacemaker.

PubMed

Lee, Michael S; Nguyen, Heajung; Shlofmitz, Richard

2017-02-01

We analyzed the incidence of bradycardia and the safety of patients with severely calcified coronary lesions who underwent orbital atherectomy without the insertion of a temporary pacemaker. The presence of severely calcified coronary lesions can increase the complexity of percutaneous coronary intervention due to the difficulty in advancing and optimally expanding the stent. High-pressure inflations to predilate calcified lesions may cause angiographic complications like perforation and dissection. Suboptimal stent expansion is associated with stent thrombosis and restenosis. Orbital atherectomy safely and effectively modifies calcified plaque to facilitate optimal stent expansion. The incidence of bradycardia in orbital atherectomy is unknown. Fifty consecutive patients underwent orbital atherectomy from February 2014 to September 2016 at our institution, none of whom underwent insertion of a temporary pacemaker. The final analysis included 47 patients in this retrospective study as 3 patients were excluded because of permanent pacemaker implantation. The primary endpoint was significant bradycardia, defined as bradycardia requiring emergent pacemaker placement or a heart rate <50 bpm at the end of atherectomy. The primary endpoint occurred in 4% of all patients, all driven by patients who experienced a heart rate decreasing to <50 bpm. The major adverse cardiac and cerebral event rate was 6%, driven by death (2%) and myocardial infarction (4%). No patient experienced target-vessel revascularization, stroke, or stent thrombosis. Angiographic complications included perforation in 2%, slow-flow in 4%, and flow-limiting dissection in 0%. Significant bradycardia was uncommon during orbital atherectomy. Performing orbital atherectomy without a temporary pacemaker appears to be safe.

Incidence of ventricular tachyarrhythmias during permanent pacemaker therapy in low-risk patients results from the German multicentre EVENTS study.

PubMed

Faber, Thomas S; Gradinger, Robert; Treusch, Sven; Morkel, Carsten; Brachmann, Johannes; Bode, Christoph; Zehender, Manfred

2007-09-01

Current studies found an incidence of 12-31% ventricular tachyarrhythmias and sudden cardiac death during cardiac pacing months or even years after pacemaker insertion. MADIT(12) and MUSTT(13) demonstrated that patients with poor LV function after Myocardial infarction (MI) showing non-sustained ventricular tachycardia (nsVT) and inducibility during electrophysiologic testing benefit from an ICD. The present study was dedicated to assess the global incidence of non-sustained ventricular arrhythmias in a general population of pacemaker patients. Special regard was on patients with a potential ICD indication, e.g. those matching the MADIT/MUSTT criteria. Two hundred and thirty-one patients (72 +/- 11 years; 134 men) with an indication for dual chamber pacing entered the study. In all patients pacemaker systems capable of automatic storing of intracardiac electrocardiograms were implanted (Pulsar, Discovery, Guidant). Follow-up time was 15 months after inclusion. In 54 (25.7%) of 210 patients with at least one follow-up, episodes of nsVT were documented by stored electrocardiograms (up to >30 beats, >200 b.p.m.). Multiple-up to nine-episodes of ventricular tachycardia were retrieved in 31 of these patients. Three out of 14 patients with an LVEF <40% after MI presented nsVT during the follow-up. One of these patients received an ICD. A significant number of pacemaker patients present with ventricular tachycardia. Intracardiac electrocardiograms and alert functions from pacemakers may enhance physicians' awareness of the patient's intrinsic arrhythmic profile and help uncover underlying mechanisms of arrhythmias by storing the initiation of the arrhythmia.

Action potential processing in a detailed Purkinje cell model reveals a critical role for axonal compartmentalization

PubMed Central

Masoli, Stefano; Solinas, Sergio; D'Angelo, Egidio

2015-01-01

The Purkinje cell (PC) is among the most complex neurons in the brain and plays a critical role for cerebellar functioning. PCs operate as fast pacemakers modulated by synaptic inputs but can switch from simple spikes to complex bursts and, in some conditions, show bistability. In contrast to original works emphasizing dendritic Ca-dependent mechanisms, recent experiments have supported a primary role for axonal Na-dependent processing, which could effectively regulate spike generation and transmission to deep cerebellar nuclei (DCN). In order to account for the numerous ionic mechanisms involved (at present including Nav1.6, Cav2.1, Cav3.1, Cav3.2, Cav3.3, Kv1.1, Kv1.5, Kv3.3, Kv3.4, Kv4.3, KCa1.1, KCa2.2, KCa3.1, Kir2.x, HCN1), we have elaborated a multicompartmental model incorporating available knowledge on localization and gating of PC ionic channels. The axon, including initial segment (AIS) and Ranvier nodes (RNs), proved critical to obtain appropriate pacemaking and firing frequency modulation. Simple spikes initiated in the AIS and protracted discharges were stabilized in the soma through Na-dependent mechanisms, while somato-dendritic Ca channels contributed to sustain pacemaking and to generate complex bursting at high discharge regimes. Bistability occurred only following Na and Ca channel down-regulation. In addition, specific properties in RNs K currents were required to limit spike transmission frequency along the axon. The model showed how organized electroresponsive functions could emerge from the molecular complexity of PCs and showed that the axon is fundamental to complement ionic channel compartmentalization enabling action potential processing and transmission of specific spike patterns to DCN. PMID:25759640

Accurate means of detecting and characterizing abnormal patterns of ventricular activation by phase image analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Botvinick, E.H.; Frais, M.A.; Shosa, D.W.

1982-08-01

The ability of scintigraphic phase image analysis to characterize patterns of abnormal ventricular activation was investigated. The pattern of phase distribution and sequential phase changes over both right and left ventricular regions of interest were evaluated in 16 patients with normal electrical activation and wall motion and compared with those in 8 patients with an artificial pacemaker and 4 patients with sinus rhythm with the Wolff-Parkinson-White syndrome and delta waves. Normally, the site of earliest phase angle was seen at the base of the interventricular septum, with sequential change affecting the body of the septum and the cardiac apex andmore » then spreading laterally to involve the body of both ventricles. The site of earliest phase angle was located at the apex of the right ventricle in seven patients with a right ventricular endocardial pacemaker and on the lateral left ventricular wall in one patient with a left ventricular epicardial pacemaker. In each case the site corresponded exactly to the position of the pacing electrode as seen on posteroanterior and left lateral chest X-ray films, and sequential phase changes spread from the initial focus to affect both ventricles. In each of the patients with the Wolff-Parkinson-White syndrome, the site of earliest ventricular phase angle was located, and it corresponded exactly to the site of the bypass tract as determined by endocardial mapping. In this way, four bypass pathways, two posterior left paraseptal, one left lateral and one right lateral, were correctly localized scintigraphically. On the basis of the sequence of mechanical contraction, phase image analysis provides an accurate noninvasive method of detecting abnormal foci of ventricular activation.« less

Cardiac Sarcoidosis: The Impact of Age and Implanted Devices on Survival.

PubMed

Zhou, Ying; Lower, Elyse E; Li, Hui-Ping; Costea, Alexandru; Attari, Mehran; Baughman, Robert P

2017-01-01

To assess the clinical characteristics, diagnosis, and outcome of cardiac sarcoidosis in a single institution sarcoidosis clinic. Patients with cardiac sarcoidosis were identified using refined World Association of Sarcoidosis and Other Granulomatous Diseases (WASOG) criteria of highly probable and probable. Patient demographics, local and systemic treatments, and clinical outcome were collected. Of the 1,815 patients evaluated over a 6-year period, 73 patients met the WASOG criteria for cardiac sarcoidosis. The median age at diagnosis was 46 years, with a median follow-up of 8.8 years. Reduced left ventricular ejection fraction (LVEF) was the most common manifestation (54.8%). Patients with arrhythmias experienced ventricular tachycardia or severe heart block, (35.6% and 19.2%, respectively) with or without reduced LVEF. A total of 45 (61.6%) patients underwent cardiac PET scan and/or MRI, with 41 (91.1%) having a positive study. During follow-up, 10 patients (13.7%) either underwent transplant (n = 3) or died (n = 7) from sarcoidosis. Kaplan-Meier survival curves revealed 5- and 10-year survival rates of 95.5% and 93.4%, respectively. Univariate factors of age at diagnosis < 46 years, implantation of pacemaker or defibrillator, mycophenolate treatment, or LVEF > 40% were associated with improved survival. Cox regression analysis demonstrated that age ≥ 46 years and lack of an implanted pacemaker or defibrillator were the only independent predictors of mortality. The new WASOG criteria were able to characterize cardiac involvement in our sarcoidosis clinic. Age and lack of pacemaker or defibrillator were the significant predictors of mortality for cardiac sarcoidosis, and reduced LVEF < 40% was associated with worse prognosis. ClinicalTrials.gov; No.: NCT02356445; URL: www.clinicaltrials.gov. Copyright © 2016 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

Transcatheter leadless cardiac pacing: The new alternative solution.

PubMed

Da Costa, Antoine; Axiotis, Amandine; Romeyer-Bouchard, Cécile; Abdellaoui, Loucif; Afif, Zahi; Guichard, Jean Baptiste; Gerbay, Antoine; Isaaz, Karl

2017-01-15

A lack of information about the feasibility and safety of leadless pacemaker (LPMs) exists in a fragile population of patients with limited venous anatomy access or conventional pacemaker (PM) contraindication. Accordingly, the goal of this prospective observational study was to report our experience with this new leadless technology in a subset of patients with contraindication or limited venous access. Between May 2015 and July 2016, 14 patients were consecutively included. The indications for initial PM implantation were atrioventricular (AV) block in 10/14 patients (71%), bradyarrhythmia in one (7%), and uncontrolled atrial fibrillation (AFib) requiring AV-node ablation in three (21.5%). AFib was observed in 9 of the 14 patients (64.3%) and 3 were completely dependent with no escape rhythm (21.5%). Normal access pathways via the right or left subclavian veins were occluded due to previous PM implantations and revisions in 4 patients (28.6%) and total vena cava occlusion in 3 (21.4%). End-stage renal disease with hemodialysis was present in 8 (57%) with either local-device infections or presence of long-term implanted dialysis catheters. Evidence of previous bilaterally-infected pectoral tissue was present in 3 patients (21.5%). All procedures were successful (100%) and electrical parameters remained stable over time. No direct pacemaker-related adverse events were reported, including mechanical complications, except for one ventricular fibrillation one day post-implantation under very specific conditions. This series demonstrated very stable performance and reassuring safety results during mid-term follow-up in a very fragile population requiring a PM. The Micra LPM constitutes an excellent alternative to the epicardial surgical approach in this very fragile population. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Use of Microcomputers and Personal Computers in Pacing

PubMed Central

Sasmor, L.; Tarjan, P.; Mumford, V.; Smith, E.

1983-01-01

This paper describes the evolution from the early discrete circuit pacemaker of the past to the sophisticated microprocessor based pacemakers of today. The necessary computerized supporting instrumentation is also described. Technological and economical reasons for this evolution are discussed.

[Long-term effects of permanent pacemaker implantation on tricuspid valve regurgitation].

PubMed

Ren, Chong-lei; Wang, Yao; Wang, Rong; Li, Bo-jun; Geng, Ren-yi; Gao, Chang-qing

2012-08-14

To explore the long-term effects of permanent pacemaker implantation (PPI) on tricuspid valve regurgitation (TR) in Chinese patients so as to determine the incidence and related factors, evaluate its effects on heart structure and function and ascertain the exact mechanism of TR after PPI. A total of 430 patients undergoing permanent pacemaker replacement at our hospital between January 2000 and June 2011 were recruited. The patients with isolated atrial lead implantation procedures, significant heart valve disease or chronic obstructive pulmonary disease were excluded. The data of 108 patients who had Doppler echocardiograms performed before the first pacemaker implantation procedure and this pacemaker replacement procedure were obtained and retrospectively analyzed. According to the post-implant grade of TR, the patients were divided into two groups: normal tricuspid (n = 79) and abnormal tricuspid (n = 29). Their clinical characteristics and echocardiographic data between two groups were analyzed and compared. The mean follow-up time (from the first pacemaker implantation) was (13 ± 6) years (range: 4 - 34). Among 108 patients with initially normal tricuspid post-implant, 29 patients (26.9%) developed significant TR during the follow-up. In comparison to those in normal tricuspid group, the patients in abnormal tricuspid group had a longer time from the first pacemaker implantation ((16 ± 7) vs (12 ± 5) years, P = 0.003), more transtricuspid leads (1.31 ± 0.66 vs 1.10 ± 0.30, P = 0.026), larger right atrial size ((38 ± 7) vs (35 ± 4) mm, P = 0.028) and higher prevalence of mild TR and mitral valve regurgitation (MR) pre-implantation (TR: 21% vs 4%, P = 0.015, MR: 28% vs 5%, P = 0.003). The size of right atrium, right ventricle and left atrium in abnormal tricuspid group were more than those in normal tricuspid group. The prevalence of significant MR post-implantation in abnormal tricuspid group was higher than that in normal tricuspid group. The ejection fraction in abnormal tricuspid group was lower than that in normal tricuspid group during the follow-up. Abnormal TR after PPI during a long-term follow-up is quite common. The related factors include the time interval from the first pacemaker implantation, number of transtricuspid lead, right atrial size, mild TR and MR pre-implantation.

Electric-field-induced magnetic domain writing in a Co wire

NASA Astrophysics Data System (ADS)

Tanaka, Yuki; Hirai, Takamasa; Koyama, Tomohiro; Chiba, Daichi

2018-05-01

We have demonstrated that the local magnetization in a Co microwire can be switched by an application of a gate voltage without using any external magnetic fields. The electric-field-induced reversible ferromagnetic phase transition was used to realize this. An internal stray field from a ferromagnetic gate electrode assisted the local domain reversal in the Co wire. This new concept of electrical domain switching may be useful for dramatically reducing the power consumption of writing information in a magnetic racetrack memory, in which a shift of a magnetic domain by electric current is utilized.

Entanglement Properties and Quantum Phases for a Fermionic Disordered One-Dimensional Wire with Attractive Interactions.

PubMed

Berkovits, Richard

2015-11-13

A fermionic disordered one-dimensional wire in the presence of attractive interactions is known to have two distinct phases, a localized and superconducting, depending on the strength of interaction and disorder. The localized region may also exhibit a metallic behavior if the system size is shorter than the localization length. Here we show that the superconducting phase has a distribution of the entanglement entropy distinct from the metallic regime. The entanglement entropy distribution is strongly asymmetric with a Lévy α-stable distribution (compared to the Gaussian metallic distribution), as is seen also for the second Rényi entropy distribution. Thus, entanglement properties may reveal properties which cannot be detected by other methods.

Magnetic field effect on photoionization cross-section of hydrogen-like impurity in cylindrical quantum wire

NASA Astrophysics Data System (ADS)

Mughnetsyan, V. N.; Barseghyan, M. G.; Kirakosyan, A. A.

2008-01-01

We consider the photoionization of a hydrogen-like impurity centre in a quantum wire approximated by a cylindrical well of finite depth in a magnetic field directed along the wire axis. The ground state energy and the wave function of the electron localized on on-axis impurity centre are calculated using the variational method. The wave functions and energies of the final states in an one-dimensional conduction subband are also presented. The dependences of photoionization cross-section of a donor centre on magnetic field and frequency of incident radiation both for parallel and perpendicular polarizations and corresponding selection rules for the allowed transitions are found in the dipole approximation. The estimates of photoionization cross-section for various values of wire radius and magnetic field induction for GaAs quantum wire embedded in Ga 1-xAl 1-xAs matrix are given.

Intralesional copper wire retention and pingyangmycin injection: an effective combinational therapy for complex venous malformation in soft tissue.

PubMed

Yuan, S-M; Hong, Z-J; Jiang, H-Q; Wang, J; Hu, X-B

2014-04-01

Complex venous malformations (VMs) may extensively involve the soft tissue. The treatment remains a challenge till now. Here we introduce a combinational therapy of copper wires and pingyangmycin (bleomycin A5,PYM). Copper wires were retained in VMs by repeated penetration with a straight needle. Subsequently, PYM solution was injected into the lesion. Eight to 10 days later, copper wires were removed. The dressing was changed every day until the puncture pores healed. Magnetic resonance imaging scanning was performed to observe the change of VMs. From January 2001 to December 2011, 56 patients were treated. During the follow-up period, most of the VMs shrunk obviously. The symptoms were relieved or disappeared. The complications included local pain, temporary paraesthesia and moderate fever, which disappeared quickly after the removal of copper wires. This combinational therapy is a safe and effective approach for the complex VMs in soft tissue.

Ventricular fibrillation induced by coagulating mode bipolar electrocautery during pacemaker implantation in Myotonic Dystrophy type 1 patient.

PubMed

Russo, Vincenzo; Rago, Anna; DI Meo, Federica; Cioppa, Nadia Della; Papa, Andrea Antonio; Russo, Maria Giovanna; Nigro, Gerardo

2014-12-01

The occurrence of ventricular fibrillation, induced by bipolar electrocautery during elective dual chamber pacemaker implantation, is reported in a patient affected by Myotonic Distrophy type 1 with normal left ventricular ejection fraction.

[Management of surgery patients with implanted cardiac pacemakers].

PubMed

Ugljen, R; Dadić, D; Ferek-Petrić, B; Jelić, I; Letica, D; Anić, D; Husar, J

1995-01-01

Patients having cardiac pacemaker implanted may be subjected to various general surgery procedures. Application of electrosurgery for the purpose of resection and coagulation, provides a high frequency electric field which produces electric voltage on the electrodes of the pacing system. This voltage may be detected within the pacing system, and various arrhythmias can be provoked in correlation with underlying rhythm and mode of pacing. Preoperative patient control and proper pacemaker programming can prevent the pacing malfunctions due to the electrosurgery application. Appropriate positioning of the neutral electrode in relation to the pacing system avoids the electric fields intersection and decreases their interference.

Runaway pacemaker: a forgotten phenomenon?

PubMed

Ortega, Daniel F; Sammartino, M Victoria; Pellegrino, Graciela M M; Barja, Luis D; Albina, Gaston; Segura, Eliseo V; Balado, Roberto; Laiño, Ruben; Giniger, Alberto G

2005-11-01

Runaway is an uncommon pacemaker dysfunction, characterized by fast and erratic spikes at non-physiological rates. This infrequent but potentially lethal failure mode may be related to low battery voltage. Four single chamber pacemaker patients were analyzed (Medtronic Minix ST 8330, Minneapolis, MN, had been implanted in two patients and two CPI Triumph VR 1124, St Paul, MN, in the other two). They had been admitted because of presyncopal episodes. Typical high rate stimuli at 2000 ppm alternating with pacing at 60-65 ppm were recorded in all ECGs. Lead system tests were normal. The pulse generators had to be replaced.

Nuclear-powered pacemaker fuel cladding study. [Difficulty of dissolving cladding and /sup 238/PuO/sub 2/ for obtaining materials for acts of terrorism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shoup, R.L.

1976-07-01

The fabrication of fuel capsules with refractory metal and alloy clads used in nuclear-powered cardiac pacemakers precludes the expedient dissolution of the clad in inorganic acid solutions. An experiment to measure penetration rates of acids on commonly used fuel pellet clads indicated that it is not impossible, but that it would be very difficult to dissolve the multiple cladding. This work was performed because of a suggestion that a /sup 238/PuO/sub 2/-powered pacemaker could be transformed into a terrorism weapon.

Pacemaker mediated tachycardia as a complication of the autointrinsic conduction search function.

PubMed

Dennis, Malcolm J; Sparks, Paul B

2004-06-01

The autointrinsic conduction search (AICS) option, featured on some DDD pacemakers, performs periodic assessments of atrioventricular (AV) conduction capability during a single beat AV delay extension. Demonstration of ventricular conduction during the prolonged AV delay, permits ongoing AV delay extension if the patient's intrinsic conduction is preferred to ventricular pacing. A case is presented where the wide separation of atrial and ventricular pacing during the conduction search permitted retrograde ventriculoatrial conduction, precipitating pacemaker mediated tachycardia (PMT) on seven occasions in one patient. Two onset patterns are reported, both attributable to the AICS option. Recommendations for prevention strategies are made.

Popeye domain containing proteins are essential for stress-mediated modulation of cardiac pacemaking in mice

PubMed Central

Froese, Alexander; Breher, Stephanie S.; Waldeyer, Christoph; Schindler, Roland F.R.; Nikolaev, Viacheslav O.; Rinné, Susanne; Wischmeyer, Erhard; Schlueter, Jan; Becher, Jan; Simrick, Subreena; Vauti, Franz; Kuhtz, Juliane; Meister, Patrick; Kreissl, Sonja; Torlopp, Angela; Liebig, Sonja K.; Laakmann, Sandra; Müller, Thomas D.; Neumann, Joachim; Stieber, Juliane; Ludwig, Andreas; Maier, Sebastian K.; Decher, Niels; Arnold, Hans-Henning; Kirchhof, Paulus; Fabritz, Larissa; Brand, Thomas

2012-01-01

Cardiac pacemaker cells create rhythmic pulses that control heart rate; pacemaker dysfunction is a prevalent disorder in the elderly, but little is known about the underlying molecular causes. Popeye domain containing (Popdc) genes encode membrane proteins with high expression levels in cardiac myocytes and specifically in the cardiac pacemaking and conduction system. Here, we report the phenotypic analysis of mice deficient in Popdc1 or Popdc2. ECG analysis revealed severe sinus node dysfunction when freely roaming mutant animals were subjected to physical or mental stress. In both mutants, bradyarrhythmia developed in an age-dependent manner. Furthermore, we found that the conserved Popeye domain functioned as a high-affinity cAMP-binding site. Popdc proteins interacted with the potassium channel TREK-1, which led to increased cell surface expression and enhanced current density, both of which were negatively modulated by cAMP. These data indicate that Popdc proteins have an important regulatory function in heart rate dynamics that is mediated, at least in part, through cAMP binding. Mice with mutant Popdc1 and Popdc2 alleles are therefore useful models for the dissection of the mechanisms causing pacemaker dysfunction and could aid in the development of strategies for therapeutic intervention. PMID:22354168

Selective vibration sensing: a new concept for activity-sensing rate-responsive pacing.

PubMed

Lau, C P; Stott, J R; Toff, W D; Zetlein, M B; Ward, D E; Camm, A J

1988-09-01

A clinically available model of an activity-sensing, rate-responsive pacemaker (Activitrax, Medtronic) utilizes body vibration during exercise as an indicator of the need for a rate increase. Although having the advantage of rapid onset of rate response, this system lacks specificity and the rate response does not closely correlate with the level of exertion. In addition, this pacemaker is susceptible to the effects of extraneous vibration. In this study involving 20 normal subjects fitted with an external Activitrax pacemaker, the rate responses to a variety of exercises were studied and were compared with the corresponding sinus rates. The vibration generated at the level of the pacemaker was also measured by accelerometers in three axes. Only a fair correlation (r = 0.51) was achieved between the pacemaker rate and the sinus rate. The total root mean square value of acceleration in either the anteroposterior or the vertical axes was found to have a better correlation (r = 0.8). As the main accelerations during physical activities were in the lower frequency range (0.1-4 Hz), a low-pass filter was used to reduce the influence of extraneous vibration. Selective sensing of the acceleration level may be usefully implemented in an algorithm for activity pacing.

Differentially Timed Extracellular Signals Synchronize Pacemaker Neuron Clocks

PubMed Central

Collins, Ben; Kaplan, Harris S.; Cavey, Matthieu; Lelito, Katherine R.; Bahle, Andrew H.; Zhu, Zhonghua; Macara, Ann Marie; Roman, Gregg; Shafer, Orie T.; Blau, Justin

2014-01-01

Synchronized neuronal activity is vital for complex processes like behavior. Circadian pacemaker neurons offer an unusual opportunity to study synchrony as their molecular clocks oscillate in phase over an extended timeframe (24 h). To identify where, when, and how synchronizing signals are perceived, we first studied the minimal clock neural circuit in Drosophila larvae, manipulating either the four master pacemaker neurons (LNvs) or two dorsal clock neurons (DN1s). Unexpectedly, we found that the PDF Receptor (PdfR) is required in both LNvs and DN1s to maintain synchronized LNv clocks. We also found that glutamate is a second synchronizing signal that is released from DN1s and perceived in LNvs via the metabotropic glutamate receptor (mGluRA). Because simultaneously reducing Pdfr and mGluRA expression in LNvs severely dampened Timeless clock protein oscillations, we conclude that the master pacemaker LNvs require extracellular signals to function normally. These two synchronizing signals are released at opposite times of day and drive cAMP oscillations in LNvs. Finally we found that PdfR and mGluRA also help synchronize Timeless oscillations in adult s-LNvs. We propose that differentially timed signals that drive cAMP oscillations and synchronize pacemaker neurons in circadian neural circuits will be conserved across species. PMID:25268747

MRI-conditional pacemakers: current perspectives.

PubMed

Ferreira, António M; Costa, Francisco; Tralhão, António; Marques, Hugo; Cardim, Nuno; Adragão, Pedro

2014-01-01

Use of both magnetic resonance imaging (MRI) and pacing devices has undergone remarkable growth in recent years, and it is estimated that the majority of patients with pacemakers will need an MRI during their lifetime. These investigations will generally be denied due to the potentially dangerous interactions between cardiac devices and the magnetic fields and radio frequency energy used in MRI. Despite the increasing reports of uneventful scanning in selected patients with conventional pacemakers under close surveillance, MRI is still contraindicated in those circumstances and cannot be considered a routine procedure. These limitations prompted a series of modifications in generator and lead engineering, designed to minimize interactions that could compromise device function and patient safety. The resulting MRI-conditional pacemakers were first introduced in 2008 and the clinical experience gathered so far supports their safety in the MRI environment if certain conditions are fulfilled. With this technology, new questions and controversies arise regarding patient selection, clinical impact, and cost-effectiveness. In this review, we discuss the potential risks of MRI in patients with electronic cardiac devices and present updated information regarding the features of MRI-conditional pacemakers and the clinical experience with currently available models. Finally, we provide some guidance on how to scan patients who have these devices and discuss future directions in the field.

High sensitivity of spontaneous spike frequency to sodium leak current in a Lymnaea pacemaker neuron.

PubMed

Lu, T Z; Kostelecki, W; Sun, C L F; Dong, N; Pérez Velázquez, J L; Feng, Z-P

2016-12-01

The spontaneous rhythmic firing of action potentials in pacemaker neurons depends on the biophysical properties of voltage-gated ion channels and background leak currents. The background leak current includes a large K + and a small Na + component. We previously reported that a Na + -leak current via U-type channels is required to generate spontaneous action potential firing in the identified respiratory pacemaker neuron, RPeD1, in the freshwater pond snail Lymnaea stagnalis. We further investigated the functional significance of the background Na + current in rhythmic spiking of RPeD1 neurons. Whole-cell patch-clamp recording and computational modeling approaches were carried out in isolated RPeD1 neurons. The whole-cell current of the major ion channel components in RPeD1 neurons were characterized, and a conductance-based computational model of the rhythmic pacemaker activity was simulated with the experimental measurements. We found that the spiking rate is more sensitive to changes in the Na + leak current as compared to the K + leak current, suggesting a robust function of Na + leak current in regulating spontaneous neuronal firing activity. Our study provides new insight into our current understanding of the role of Na + leak current in intrinsic properties of pacemaker neurons. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Acute exposure to 2G phase shifts the rat circadian timing system

NASA Technical Reports Server (NTRS)

Hoban-Higgins, T. M.; Murakami, D. M.; Tandon, T.; Fuller, C. A.

1995-01-01

The circadian timing system (CTS) provides internal and external temporal coordination of an animal's physiology and behavior. In mammals, the generation and coordination of these circadian rhythms is controlled by a neural pacemaker, the suprachiasmatic nucleus (SCN), located within the hypothalamus. The pacemaker is synchronized to the 24 hour day by time cures (zeitgebers) such as the light/dark cycle. When an animal is exposed to an environment without time cues, the circadian rhythms maintain internal temporal coordination, but exhibit a 'free-running' condition in which the period length is determined by the internal pacemaker. Maintenance of internal and external temporal coordination are critical for normal physiological and psychological function in human and non-human primates. Exposure to altered gravitational environments has been shown to affect the amplitude, mean, and timing of circadian rhythms in species ranging from unicellular organisms to man. However, it has not been determined whether altered gravitational fields have a direct effect on the neural pacemaker, or affect peripheral parameters. In previous studies, the ability of a stimulus to phase shift circadian rhythms was used to determine whether a stimulus has a direct effect on the neural pacemaker. The present experiment was performed in order to determine whether acute exposure to a hyperdynamic field could phase shift circadian rhythms.

The Use of Ultrasound to Improve Axillary Vein Access and Minimize Complications during Pacemaker Implantation.

PubMed

Esmaiel, Abdullah; Hassan, Jeremy; Blenkhorn, Fay; Mardigyan, Vartan

2016-05-01

The Agency for Healthcare Research and Quality in the United States recommends the use of ultrasound (US) for central venous access to improve patient outcomes. However, in a recent publication, US is still underutilized for axillary vein access during pacemaker implantation. We sought to describe a technique for US-guided axillary vein access during pacemaker implantation and to report complication rates and success rate. Retrospective data collection included success rate and complications on all pacemaker implants by one operator since implementing the systematic use of US at our institution, from November 2012 to January 2015. For the last 59 cases, data were collected prospectively to include time of venous access and number of attempts. A total of 403 consecutive patients were included in the analysis. Two leads were implanted in 255 cases and one lead was implanted in 148 cases. The rate of successful US-guided access was 99.25%. There were no access-related complications. The average number of venipuncture attempts was 1.18 per patient. The average time to obtain venous access was 2.24 minutes including the time to apply the sterile US sleeve. The described technique has the potential to improve the success rate of axillary vein access and minimize complications during pacemaker implantation. ©2016 Wiley Periodicals, Inc.

Spontaneous activity of isolated dopaminergic periglomerular cells of the main olfactory bulb.

PubMed

Puopolo, Michelino; Bean, Bruce P; Raviola, Elio

2005-11-01

We examined the electrophysiological properties of a population of identified dopaminergic periglomerular cells of the main olfactory bulb using transgenic mice in which catecholaminergic neurons expressed human placental alkaline phosphatase (PLAP) on the outer surface of the plasma membrane. After acute dissociation, living dopaminergic periglomerular cells were identified by a fluorescently labeled monoclonal antibody to PLAP. In current-clamp mode, dopaminergic periglomerular cells spontaneously generated action potentials in a rhythmic fashion with an average frequency of 8 Hz. The hyperpolarization-activated cation current (Ih) did not seem important for pacemaking because blocking the current with ZD 7288 or Cs+ had little effect on spontaneous firing. To investigate what ionic currents do drive pacemaking, we performed action-potential-clamp experiments using records of pacemaking as voltage command in voltage-clamp experiments. We found that substantial TTX-sensitive Na+ current flows during the interspike depolarization. In addition, substantial Ca2+ current flowed during the interspike interval, and blocking Ca2+ current hyperpolarized the neurons and stopped spontaneous firing. These results show that dopaminergic periglomerular cells have intrinsic pacemaking activity, supporting the possibility that they can maintain a tonic release of dopamine to modulate the sensitivity of the olfactory system during odor detection. Calcium entry into these neurons provides electrical drive for pacemaking as well as triggering transmitter release.

Conduction Abnormalities and Permanent Pacemaker Implantation After Transcatheter Aortic Valve Replacement Using the Repositionable LOTUS Device: The United Kingdom Experience.

PubMed

Rampat, Rajiv; Khawaja, M Zeeshan; Hilling-Smith, Roland; Byrne, Jonathan; MacCarthy, Philip; Blackman, Daniel J; Krishnamurthy, Arvindra; Gunarathne, Ashan; Kovac, Jan; Banning, Adrian; Kharbanda, Raj; Firoozi, Sami; Brecker, Stephen; Redwood, Simon; Bapat, Vinayak; Mullen, Michael; Aggarwal, Suneil; Manoharan, Ganesh; Spence, Mark S; Khogali, Saib; Dooley, Maureen; Cockburn, James; de Belder, Adam; Trivedi, Uday; Hildick-Smith, David

2017-06-26

The authors report the incidence of pacemaker implantation up to hospital discharge and the factors influencing pacing rate following implantation of the LOTUS bioprosthesis (Boston Scientific, Natick, Massachusetts) in the United Kingdom. Transcatheter aortic valve replacement (TAVR) is associated with a significant need for permanent pacemaker implantation. Pacing rates vary according to the device used. The REPRISE II (Repositionable Percutaneous Replacement of Stenotic Aortic Valve Through Implantation of Lotus Valve System) trial reported a pacing rate of 29% at 30 days after implantation of the LOTUS device. Data were collected retrospectively on 228 patients who had the LOTUS device implanted between March 2013 and February 2015 across 10 centers in the United Kingdom. Twenty-seven patients (12%) had pacemakers implanted pre-procedure and were excluded from the analysis. Patients were aged 81.2 ± 7.7 years; 50.7% were male. The mean pre-procedural QRS duration was 101.7 ± 20.4 ms. More than one-half of the cohort (n = 111, 55%) developed new left bundle branch block (LBBB) following the procedure. Permanent pacemakers were implanted in 64 patients (32%) with a median time to insertion of 3.0 ± 3.4 days. Chief indications for pacing were atrioventricular (AV) block (n = 46, 72%), or LBBB with 1st degree AV block (n = 11, 17%). Amongst those who received a pacemaker following TAVR the pre-procedural electrocardiogram findings included: No conduction disturbance (n = 41, 64%); 1st degree AV block (n = 10, 16%); right bundle branch block (n = 6, 9%) and LBBB (n = 5, 8%). LBBB (but not permanent pacemaker) occurred more frequently in patients who had balloon aortic valvuloplasty before TAVR (odds ratio [OR]: 1.25; p = 0.03). Pre-procedural conduction abnormality (composite of 1st degree AV block, hemiblock, right bundle branch block, LBBB) was independently associated with the need for permanent pacemaker (OR: 2.54; p = 0.048). The absence of aortic valve calcification was also associated with a higher pacing rate (OR: 0.55; p = 0.031). Multivariate regression analysis did not show an independent association between depth of implant, valve oversizing, balloon post-dilatation, and the need for pacing post-procedure. Following implantation of the repositionable LOTUS valve, 55% of patients developed LBBB and 32% of patients required a pacemaker during their index hospital admission. Patients with pre-procedural conduction disturbance and non-calcified aortic valves were more likely to need pacing. No other anatomic features were identified with increased pacing requirement with the LOTUS device. Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.

Financial audit of antitachycardia pacing for the control of recurrent supraventricular tachycardia.

PubMed Central

Griffith, M J; Bexton, R S; McComb, J M

1993-01-01

OBJECTIVE--To assess the financial implications of antitachycardia pacing in patients with frequent supraventricular tachycardia. PATIENTS--Intertach pacemakers were implanted in 25 patients (mean age 47 years, five men): 22 had atrioventricular nodal reentry tachycardia. The patients had failed a mean of 4.9 (range zero to eight) drugs and had been admitted to hospital 3.7 (zero to 31) times over a symptomatic period of 13.9 years (two months to 54 years). RESULTS--The mean admission time for implantation was 2.8 (two to seven) days. One patient with Wolff-Parkinson-White syndrome subsequently underwent surgery. Infection occurred in two patients, and pain over the pacemaker required its resiting in two. Two patients have had one admission each for tachycardia. Six patients remain on anti-arrhythmic drugs. Costs were calculated including value added tax, capital charges, and allocated overheads. The cost a year before pacing was 1174 pounds including drug costs, clinic visits, and hospital admissions. The mean cost of pacemaker implantation was 3364.22 pounds, including the pacemaker and lead, admission and procedure, readmissions and first pacing check. Subsequent annual follow up cost was 73.72 pounds including annual clinic visits and drug costs. The cost of pacing is 4241 pounds whereas medical management costs 7044 pounds assuming pacemaker life of six years: with a 10 year life the cost is 4537 pounds compared with 11,740 pounds: with a 12 year life the cost is 4685 pounds compared with 14,088 pounds. CONCLUSION--The excess cost of implantation of an antitachycardia pacemaker is minimal in patients with frequent supraventricular tachycardia despite drug treatment and is justified by excellent control of symptoms and reduction of drug use and hospital admissions. PMID:8461232

Financial audit of antitachycardia pacing for the control of recurrent supraventricular tachycardia.

PubMed

Griffith, M J; Bexton, R S; McComb, J M

1993-03-01

To assess the financial implications of antitachycardia pacing in patients with frequent supraventricular tachycardia. Intertach pacemakers were implanted in 25 patients (mean age 47 years, five men): 22 had atrioventricular nodal reentry tachycardia. The patients had failed a mean of 4.9 (range zero to eight) drugs and had been admitted to hospital 3.7 (zero to 31) times over a symptomatic period of 13.9 years (two months to 54 years). The mean admission time for implantation was 2.8 (two to seven) days. One patient with Wolff-Parkinson-White syndrome subsequently underwent surgery. Infection occurred in two patients, and pain over the pacemaker required its resiting in two. Two patients have had one admission each for tachycardia. Six patients remain on anti-arrhythmic drugs. Costs were calculated including value added tax, capital charges, and allocated overheads. The cost a year before pacing was 1174 pounds including drug costs, clinic visits, and hospital admissions. The mean cost of pacemaker implantation was 3364.22 pounds, including the pacemaker and lead, admission and procedure, readmissions and first pacing check. Subsequent annual follow up cost was 73.72 pounds including annual clinic visits and drug costs. The cost of pacing is 4241 pounds whereas medical management costs 7044 pounds assuming pacemaker life of six years: with a 10 year life the cost is 4537 pounds compared with 11,740 pounds: with a 12 year life the cost is 4685 pounds compared with 14,088 pounds. The excess cost of implantation of an antitachycardia pacemaker is minimal in patients with frequent supraventricular tachycardia despite drug treatment and is justified by excellent control of symptoms and reduction of drug use and hospital admissions.

Early Performance and Safety of the Micra Transcatheter Pacemaker in Pigs.

PubMed

Bonner, Matthew; Eggen, Michael; Haddad, Tarek; Sheldon, Todd; Williams, Eric

2015-11-01

The Micra® Transcatheter Pacing System (TPS; Medtronic Inc., Minneapolis, MN, USA) is a miniaturized single-chamber pacemaker system that is delivered via catheter through the femoral vein. In this study, the electrical performance was compared between the TPS and a traditional leaded pacemaker. In addition, the safety profile of the two systems was compared by thorough monitoring for a number of adverse events. The TPS was implanted in the right ventricular apex of 10 Yucatan mini pigs and a Medtronic single-lead pacemaker (SLP) was implanted in the right ventricular apex of another 10 pigs and connected to a traditional pacemaker. The electrical performance of all devices was monitored for 12 weeks. The safety profile of each system was characterized using x-ray, computed tomography, ultrasound, blood work, and necropsy to monitor for a variety of adverse events. At implant the mean pacing thresholds were 0.58 ± 0.17 V @0.24 ms and 0.75 ± 0.29 V @0.21 ms for the TPS and the SLP respectively. After 12 weeks, mean thresholds were 0.94 ± 0.46 V and 1.85 ± 0.75 V (P < 0.0001). There were two pulmonary emboli that were small and past the tertiary branch, and one occurred in each arm. There were also two infections with one in each arm. There were no dislodgements (macro or micro), tissue injury, tamponade, or valve injury. Overall, despite the 10-fold size reduction of the Micra TPS, it appears to perform similarly and have a similar safety profile to a traditional pacemaker system. © 2015 Medtronic PLC. Pacing and Clinical Electrophysiology published by Wiley Periodicals, Inc.

Transfemoral access when superior venous approach is not feasible equals overall success of permanent pacemaker implantation. Ten-year series.

PubMed

García Guerrero, Juan J; Fernández de la Concha Castañeda, Joaquín; Doblado Calatrava, Manuel; Redondo Méndez, Ángel; Lázaro Medrano, Manuel; Merchán Herrera, Antonio

2017-06-01

When permanent pacemaker implantation is not possible or advisable via superior venous access (i.e., axillary or subclavian veins), safe and feasible surgical alternatives are required. The femoral approach is relatively unknown and seldom studied. This single-center study analyzed 10-year outcomes of a femoral implantation approach. Data about the implantation procedure (indication, approach, lead and pacemaker models, complications), patient characteristics (age, sex, medications, comorbidities), and follow-up were analyzed for all permanent pacemaker implantations using the femoral approach between June 2001 and June 2011. A permanent pacemaker was implanted with the femoral approach in 50 patients (mean age, 76 years [range: 45-96], 31 [61%] men). The most frequent indication was atrioventricular block, associated with sinus rhythm in 30 patients and with atrial fibrillation in eight patients. Overall, 20 patients (40%) were treated with oral anticoagulants postimplantation. Mean implantation time was 64 minutes (range: 20-210) and mean fluoroscopy time was 6.7 minutes (range: 0.2-50). Minimum follow-up window was 1 year (June 2012), with a mean of 50 months [range: 1-113]). No deaths, septic episodes, or severe complications were associated with the procedure, acute or long-term. Follow-up data were available for 46 patients, of who 21 (46%) died during follow-up (mean age, 87 years [range: 73-101]). No cause of death was associated with the femoral technique. Permanent pacemaker implantation through femoral access is not difficult for an experienced implant surgeon. Outcomes were comparable to systems implanted by superior venous approach, and no severe complications were observed at 10-year follow-up. © 2017 Wiley Periodicals, Inc.

Twenty-Seven Years Experience With Transvenous Pacemaker Implantation in Children Weighing <10 kg.

PubMed

Konta, Laura; Chubb, Mark Henry; Bostock, Julian; Rogers, Jan; Rosenthal, Eric

2016-02-01

Epicardial pacemaker implantation is the favored approach in children weighing <10 kg in many units. The high incidence of premature failure and fractures with earlier epicardial leads led our unit to undertake transvenous pacemaker implantation in neonates and infants from 1987. To date there have been no long-term follow-up reports of what is for many a controversial strategy. Between 1987 and 2003, 37 neonates and infants-median age 6.7 months (1 day to 3 years) and median weight 4.6 kg (2.7-10 kg)-had a permanent transvenous pacing system implanted. Pacing leads were placed into the right ventricular apex/outflow tract through a subclavian vein puncture with a redundant loop in the atrium. Three patients were lost to follow-up, 4 patients died from complications of cardiac surgery, and 2 patients had their system removed. At long-term follow-up in 28 patients at a median of 17.2 (range, 11.2-27.4) years, 10 patients have a single chamber ventricular pacemaker, 14 a dual chamber pacemaker, 3 a biventricular pacemaker, and 1 has a single chamber implantable cardioverter defibrillator. Subclavian vein patency was assessed in 26 patients. The overall subclavian vein occlusion rate was 10 of 13 (77%) <5 kg and 2 of 13 (15%) >5 kg during long-term follow-up. After a median of 14.3 (range, 13.4-17.6) years of pacing, 7 patients continue with their original lead. Transvenous pacing in infants <10 kg results in encouraging short- and long-term clinical outcomes. Subclavian vein occlusion remains an important complication, occurring predominantly in those weighing <5 kg. © 2016 American Heart Association, Inc.

Novel approach to epicardial pacemaker implantation in patients with limited venous access.

PubMed

Costa, Roberto; Scanavacca, Mauricio; da Silva, Kátia Regina; Martinelli Filho, Martino; Carrillo, Roger

2013-11-01

Limited venous access in certain patients increases the procedural risk and complexity of conventional transvenous pacemaker implantation. The purpose of this study was to determine a minimally invasive epicardial approach using pericardial reflections for dual-chamber pacemaker implantation in patients with limited venous access. Between June 2006 and November 2011, 15 patients underwent epicardial pacemaker implantation. Procedures were performed through a minimally invasive subxiphoid approach and pericardial window with subsequent fluoroscopy-assisted lead placement. Mean patient age was 46.4 ± 15.3 years (9 male [(60.0%], 6 female [40.0%]). The new surgical approach was used in patients determined to have limited venous access due to multiple abandoned leads in 5 (33.3%), venous occlusion in 3 (20.0%), intravascular retention of lead fragments from prior extraction in 3 (20.0%), tricuspid valve vegetation currently under treatment in 2 (13.3%), and unrepaired intracardiac defects in 2 (13.3%). All procedures were successful with no perioperative complications or early deaths. Mean operating time for isolated pacemaker implantation was 231.7 ± 33.5 minutes. Lead placement on the superior aspect of right atrium, through the transverse sinus, was possible in 12 patients. In the remaining 3 patients, the atrial lead was implanted on the left atrium through the oblique sinus, the postcaval recess, or the left pulmonary vein recess. None of the patients displayed pacing or sensing dysfunction, and all parameters remained stable throughout the follow-up period of 36.8 ± 25.1 months. Epicardial pacemaker implantation through pericardial reflections is an effective alternative therapy for those patients requiring physiologic pacing in whom venous access is limited. © 2013 Heart Rhythm Society. All rights reserved.

Significant and safe reduction of propofol sedation dose for geriatric population undergoing pacemaker implantation: randomized clinical trial.

PubMed

Hernandez-Perez, Ana Luisa; Gallardo-Hernandez, Ana Gabriela; Ordoñez-Espinosa, German; Martinez-Carrillo, Beatriz; Bermudez-Ochoa, Manuel Gerardo; Revilla-Monsalve, Cristina; Sanchez-Lopez, Jose Antonio; Saturno-Chiu, Guillemo; Leder, Ronald

2018-02-21

A previous multidisciplinary pilot study based on computer simulations for the geriatric population showed that a dose of 0.5 mg/kg/h of propofol could sedate patients older than 65 for pacemaker implantation. The present study validates that the pacemaker implantation can be done in the elderly using 0.5-1 mg/kg/h of propofol with hemodynamic stability. 66 patients from 65 to 88 years old scheduled for pacemaker implantation were randomly assigned one of three doses of propofol. The first group received 2 mg/kg/h of propofol (P2) that is within normal range of the sedation dose. The second group received 1 mg/kg/h (P1) dose and the third group received the dose of 0.5 mg/kg/h (P0.5) according to the simulation-predicted dose for geriatric populations. All patients kept MAP between 76 and 85 mmHg, with no hypotension episodes in any of the groups; therefore, they were all hemodynamically stable during the procedure. BIS was between 80 and 65 during the pacemaker implantation for the three groups, BIS of group P2 was significantly lower than the other groups. BIS in groups P1 and P0.5 was within the appropriated range for moderate sedation. Brice was positive for auditory recalls only when there was arousing noise in the operating room. Moderate sedation, adequate for pacemaker implantation, can be achieved infusing 0.5-1 mg/kg/h of propofol in elderly patients when the patient has proper analgesia management at the device implantation site. The second important condition is to avoid unnecessary and alerting auditory and mechanical stimuli in the operating room, so that the patient will remain calm.

Safety evaluation of a leadless transcatheter pacemaker for magnetic resonance imaging use.

PubMed

Soejima, Kyoko; Edmonson, Jonathan; Ellingson, Michael L; Herberg, Ben; Wiklund, Craig; Zhao, Jing

2016-10-01

Increased magnetic resonance imaging (MRI) adoption and demand are driving the need for device patients to have safe access to MRI. The aim of this study was to address the interactions of MRI with the Micra transcatheter pacemaker system. A strategy was developed to evaluate potential MRI risks including device heating, unintended cardiac stimulation, force, torque, vibration, and device malfunction. Assessment of MRI-induced device heating was conducted using a phantom containing gelled saline, and Monte Carlo simulations incorporating these results were conducted to simulate numerous combinations of human body models, position locations in the MRI scanner bore, and a variety of coil designs. Lastly, a patient with a Micra pacemaker who underwent a clinically indicated MRI scan is presented. Compared to traditional MRI conditional pacemakers, the overall risk with Micra was greatly reduced because of the small size of the device and the absence of a lead. The modeling results predicted that the nonperfused temperature rise of the device would be less than 0.4°C at 1.5 T and 0.5°C at 3 T and that the risk of device heating with multiple device implants was not increased as compared with a single device. The clinical case study revealed no MRI-related complications. The MRI safety assessment tests conducted for the Micra pacemaker demonstrate that patients with a single device or multiple devices can safely undergo MRI scans in both 1.5- and 3-T MRI scanners. No MRI-related complications were observed in a patient implanted with a Micra pacemaker undergoing a clinically indicated scan. Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Are pacemaker properties required for respiratory rhythm generation in adult turtle brain stems in vitro?

PubMed

Johnson, Stephen M; Wiegel, Liana M; Majewski, David J

2007-08-01

The role of pacemaker properties in vertebrate respiratory rhythm generation is not well understood. To address this question from a comparative perspective, brain stems from adult turtles were isolated in vitro, and respiratory motor bursts were recorded on hypoglossal (XII) nerve rootlets. The goal was to test whether burst frequency could be altered by conditions known to alter respiratory pacemaker neuron activity in mammals (e.g., increased bath KCl or blockade of specific inward currents). While bathed in artificial cerebrospinal fluid (aCSF), respiratory burst frequency was not correlated with changes in bath KCl (0.5-10.0 mM). Riluzole (50 microM; persistent Na(+) channel blocker) increased burst frequency by 31 +/- 5% (P < 0.05) and decreased burst amplitude by 42 +/- 4% (P < 0.05). In contrast, flufenamic acid (FFA, 20-500 microM; Ca(2+)-activated cation channel blocker) reduced and abolished burst frequency in a dose- and time-dependent manner (P < 0.05). During synaptic inhibition blockade with bicuculline (50 microM; GABA(A) channel blocker) and strychnine (50 muM; glycine receptor blocker), rhythmic motor activity persisted, and burst frequency was directly correlated with extracellular KCl (0.5-10.0 mM; P = 0.005). During synaptic inhibition blockade, riluzole (50 microM) did not alter burst frequency, whereas FFA (100 microM) abolished burst frequency (P < 0.05). These data are most consistent with the hypothesis that turtle respiratory rhythm generation requires Ca(2+)-activated cation channels but not pacemaker neurons, which thereby favors the group-pacemaker model. During synaptic inhibition blockade, however, the rhythm generator appears to be transformed into a pacemaker-driven network that requires Ca(2+)-activated cation channels.

Cardiac pacing for severe childhood neurally mediated syncope with reflex anoxic seizures

PubMed Central

McLeod, K; Wilson, N; Hewitt, J; Norrie, J; Stephenson, J

1999-01-01

OBJECTIVE—To determine whether permanent cardiac pacing could prevent syncope and seizures in children with frequent severe neurally mediated syncope, and if so whether dual chamber pacing was superior to single chamber ventricular pacing.
METHODS—Dual chamber pacemakers were implanted into 12 children (eight male, four female) aged 2-14 years (median 2.8 years) with frequent episodes of reflex anoxic seizures and a recorded prolonged asystole during an attack. The pacemaker was programmed to sensing only (ODO), single chamber ventricular pacing with hysteresis (VVI), and dual chamber pacing with rate drop response (DDD) for four month periods, with each patient allocated to one of the six possible sequences of these modes, according to chronological order of pacemaker implantation. The parent and patient were blinded to the pacemaker mode and asked to record all episodes of syncope or presyncope ("near miss" events). The doctor analysing the results was blinded to the patient and pacemaker mode.
RESULTS—One patient was withdrawn from the study after the pacemaker was removed because of infection. In the remaining children, both dual chamber and single chamber pacing significantly reduced the number of syncopal episodes compared with sensing only (p = 0.0078 for both). VVI was as effective as DDD for preventing syncope, but DDD was superior to VVI in reducing near miss events (p = 0.016).
CONCLUSIONS—Permanent pacing is an effective treatment for children with severe neurally mediated syncope and reflex anoxic seizures. VVI is as effective as DDD in preventing syncope and seizures, but DDD is superior in preventing overall symptoms.


Keywords: syncope; reflex anoxic seizures; pacing; paediatric cardiology PMID:10573501

Plasticity-Driven Self-Organization under Topological Constraints Accounts for Non-random Features of Cortical Synaptic Wiring

PubMed Central

Miner, Daniel; Triesch, Jochen

2016-01-01

Understanding the structure and dynamics of cortical connectivity is vital to understanding cortical function. Experimental data strongly suggest that local recurrent connectivity in the cortex is significantly non-random, exhibiting, for example, above-chance bidirectionality and an overrepresentation of certain triangular motifs. Additional evidence suggests a significant distance dependency to connectivity over a local scale of a few hundred microns, and particular patterns of synaptic turnover dynamics, including a heavy-tailed distribution of synaptic efficacies, a power law distribution of synaptic lifetimes, and a tendency for stronger synapses to be more stable over time. Understanding how many of these non-random features simultaneously arise would provide valuable insights into the development and function of the cortex. While previous work has modeled some of the individual features of local cortical wiring, there is no model that begins to comprehensively account for all of them. We present a spiking network model of a rodent Layer 5 cortical slice which, via the interactions of a few simple biologically motivated intrinsic, synaptic, and structural plasticity mechanisms, qualitatively reproduces these non-random effects when combined with simple topological constraints. Our model suggests that mechanisms of self-organization arising from a small number of plasticity rules provide a parsimonious explanation for numerous experimentally observed non-random features of recurrent cortical wiring. Interestingly, similar mechanisms have been shown to endow recurrent networks with powerful learning abilities, suggesting that these mechanism are central to understanding both structure and function of cortical synaptic wiring. PMID:26866369

Performing magnetic resonance imaging in patients with implantable pacemakers and defibrillators: results of a European Heart Rhythm Association survey.

PubMed

Marinskis, Germanas; Bongiorni, Maria Grazia; Dagres, Nikolaos; Dobreanu, Dan; Lewalter, Thorsten; Blomström-Lundqvist, Carina

2012-12-01

The purpose of our survey was to evaluate the experience, current practice and attitudes of performing magnetic resonance imaging (MRI) studies in patients with cardiac implantable electronic devices. Fifty-one centre-members of European Heart Rhythm Association Research network have responded to the survey. According to the obtained data, 55.2% of responding centres do not perform MRI scans in patients with non-MRI-certified pacemakers and 65.8% in patients with such implantable cardioverter defibrillators (ICDs). Reported complication rate in patients with non-MRI-certified devices is low and conforms to the literature data. Experience with newer MRI-compatible pacemakers and ICDs is limited to single cases in most centres. This survey shows limited experience with performing MRI studies in patients with implanted pacemakers and ICDs. In concordance with available guidelines, most centres limit MRI scans in patients with non-MRI-certified devices. The implant numbers for MRI-certified devices and experience with performing MRI scans in these patients are still low.

A SERIES OF SUPPRESSIVE SIGNALS WITHIN THE DROSOPHILA CIRCADIAN NEURAL CIRCUIT GENERATES SEQUENTIAL DAILY OUTPUTS

PubMed Central

Liang, Xitong; Holy, Timothy E; Taghert, Paul H

2017-01-01

Summary We studied the Drosophila circadian neural circuit using whole brain imaging in vivo. Five major groups of pacemaker neurons display synchronized molecular clocks, yet each exhibits a distinct phase of daily Ca2+ activation. Light and neuropeptide PDF from morning cells (s-LNv) together delay the phase of the evening (LNd) group by ~12 h; PDF alone delays the phase of the DN3 group, by ~17 h. Neuropeptide sNPF, released from s-LNv and LNd pacemakers, produces latenight Ca2+ activation in the DN1 group. The circuit also features negative feedback by PDF to truncate the s-LNv Ca2+ wave and terminate PDF release. Both PDF and sNPF suppress basal Ca2+ levels in target pacemakers with long durations by cell autonomous actions. Thus, light and neuropeptides act dynamically at distinct hubs of the circuit to produce multiple suppressive events that create the proper tempo and sequence of circadian pacemaker neuronal activities. PMID:28552314

Different Classes of Glutamate Receptors Mediate Distinct Behaviors in a Single Brainstem Nucleus

NASA Astrophysics Data System (ADS)

Dye, John; Heiligenberg, Walter; Keller, Clifford H.; Kawasaki, Masashi

1989-11-01

We have taken advantage of the increasing understanding of glutamate neuropharmacology to probe mechanisms of well-defined vertebrate behaviors. Here we report a set of experiments that suggests distinct roles for two major classes of glutamate receptors in a discrete premotor nucleus of the brainstem. The medullary pacemaker nucleus of weakly electric fish is an endogenous oscillator that controls the electric organ discharge (EOD). Its regular frequency of firing is modulated during several distinct behaviors. The pacemaker nucleus continues firing regularly when isolated in vitro, and modulatory behaviors can be reproduced by stimulating the descending input pathway. Glutamate agonists applied to the pacemaker in vitro produced increases in frequency, while glutamate antagonists selectively blocked stimulus-induced modulations. Experiments with glutamate antagonists in the intact animal resulted in specific effects on two well-characterized behaviors. Our data indicate that these behaviors are separately mediated in the pacemaker by receptors displaying characteristics of the kainate/quisqualate and N-methyl-D-aspartate subtypes of glutamate receptor, respectively.

Leadless cardiac pacemakers: present and the future.

PubMed

Chew, Derek S; Kuriachan, Vikas

2018-01-01

Pacing technology for many decades has been composed of a generator attached to leads that are usually transvenous. Recently, leadless pacemakers have been studied in clinical settings and now available for use in many countries. This includes the single-component Nanostim Leadless Cardiac Pacemaker and Micra Transcatheter Pacing System, as well as the multicomponent Wireless Stimulation Endocardial system. Clinical studies in single-component leadless pacing technology has shown that they can be successfully implanted with minimal complications. The follow-up studies also seem to confirm the findings from the initial clinical trials. These systems offer some advantages over a traditional pacing system comprised of a subcutaneous generator and transvenous leads. In many ways, these leadless systems are disruptive technologies that are changing the traditional pacemaker concept and preferred for some patients. Ongoing research is needed to better assess their long-term function, safety, and end-of-life strategies. In the future, multichamber leadless pacing is expected to be developed and perhaps obviating the need for transvenous leads and their associated complications.

Substance P modulation of TRPC3/7 channels improves respiratory rhythm regularity and ICAN-dependent pacemaker activity

PubMed Central

Ben-Mabrouk, Faiza; Tryba, Andrew Kieran

2011-01-01

Neuromodulators, such as Substance P (SubP) play an important role in modulating many rhythmic activities driven by central pattern generators (e.g., locomotion, respiration). However, the mechanism by which SubP enhances breathing regularity has not been determined. Here, we used mouse brainstem slices containing the pre-Bötzinger Complex (Pre-BötC) to demonstrate, for the first time, that SubP activates transient receptor protein canonical (TRPC) channels to enhance respiratory rhythm regularity. Moreover, SubP enhancement of network regularity is accomplished via selective enhancement of ICAN-dependent intrinsic bursting properties. In contrast to INaP-dependant pacemakers, ICAN-dependant pacemaker bursting activity is TRPC dependent. Western Blots reveal TRPC3 and TRPC7 channels are expressed in rhythmically active ventral respiratory group (VRG) island preparations. Taken together, these data suggest that SubP-mediated activation of TRPC3/7 channels underlies rhythmic ICAN-dependent pacemaker activity and enhances the regularity of respiratory rhythm activity. PMID:20345918

Substance P modulation of TRPC3/7 channels improves respiratory rhythm regularity and ICAN-dependent pacemaker activity.

PubMed

Ben-Mabrouk, Faiza; Tryba, Andrew K

2010-04-01

Neuromodulators, such as substance P (SubP), play an important role in modulating many rhythmic activities driven by central pattern generators (e.g. locomotion, respiration). However, the mechanism by which SubP enhances breathing regularity has not been determined. Here, we used mouse brainstem slices containing the pre-Bötzinger complex to demonstrate, for the first time, that SubP activates transient receptor protein canonical (TRPC) channels to enhance respiratory rhythm regularity. Moreover, SubP enhancement of network regularity is accomplished via selective enhancement of ICAN (inward non-specific cation current)-dependent intrinsic bursting properties. In contrast to INaP (persistent sodium current)-dependent pacemakers, ICAN-dependent pacemaker bursting activity is TRPC-dependent. Western Blots reveal TRPC3 and TRPC7 channels are expressed in rhythmically active ventral respiratory group island preparations. Taken together, these data suggest that SubP-mediated activation of TRPC3/7 channels underlies rhythmic ICAN-dependent pacemaker activity and enhances the regularity of respiratory rhythm activity.

Membrane currents underlying activity in frog sinus venosus

PubMed Central

Brown, Hilary F.; Giles, Wayne; Noble, Susan J.

1977-01-01

1. The spontaneous electrical activity of small strips of muscle from the sinus venosus region of the heart of Rana catesbeiana was investigated using the double sucrose gap technique. The voltage clamp was used to record the ionic currents underlying the pace-maker depolarization and the action potential. 2. The records of spontaneous electrical activity are very similar to those obtained from the sinus venosus using micro-electrodes. Moreover, the pace-maker activity is almost completely insensitive to tetrodotoxin (TTX) at 2·0 × 10-6 g/ml., which suggests that the pace-maker responses can be classified as primary, as opposed to follower pacing. 3. In response to short rectangular depolarizing voltage clamp pulses, only one inward current is activated. This current is almost completely insensitive to TTX but can be blocked by manganese ions. It appears, therefore, to be equivalent to the slow inward (Ca2+/Na+) current, Isi, of other cardiac tissues. The threshold for Isi is near to the maximum diastolic potential, indicating that it must be activated during the pace-maker depolarization. 4. Interruption of the normal pace-maker depolarization by rapid activation of the voltage clamp circuit reveals the time-dependent decay of outward current. This current reverses between -75 and -90 mV and, therefore, is probably carried mainly by potassium ions. 5. Outward current decay is not a simple exponential, and Hodgkin—Huxley analysis suggests that two distinct components of outward current may be present. One of these is activated in the potential range of the pace-maker depolarization and the other at more positive potentials. Both outward currents reach full, steady-state activation at about zero mV, i.e. within the `plateau' range of the sinus action potential. 6. These results are compared with other recently published voltage clamp data from the rabbit sino—atrial node. 7. A hypothesis for the generation of pace-maker activity is presented which involves (i) decay of outward current and (ii) activation of the slow inward current, Isi. PMID:303699

Small functional If current in sinoatrial pacemaker cells of the brown trout (Salmo trutta fario) heart despite strong expression of HCN channel transcripts.

PubMed

Hassinen, Minna; Haverinen, Jaakko; Vornanen, Matti

2017-12-01

Funny current ( I f ), formed by hyperpolarization-activated cyclic nucleotide-gated channels (HCN channels), is supposed to be crucial for the membrane clock regulating the cardiac pacemaker mechanism. We examined the presence and activity of HCN channels in the brown trout ( Salmo trutta fario ) sinoatrial (SA) pacemaker cells and their putative role in heart rate ( f H ) regulation. Six HCN transcripts (HCN1, HCN2a, HCN2ba, HCN2bb, HCN3, and HCN4) were expressed in the brown trout heart. The total HCN transcript abundance was 4.0 and 4.9 times higher in SA pacemaker tissue than in atrium and ventricle, respectively. In the SA pacemaker, HCN3 and HCN4 were the main isoforms representing 35.8 ± 2.7 and 25.0 ± 1.5%, respectively, of the total HCN transcripts. Only a small I f with a mean current density of -1.2 ± 0.37 pA/pF at -140 mV was found in 4 pacemaker cells out of 16 spontaneously beating cells examined, despite the optimization of recording conditions for I f activity. I f was not found in any of the 24 atrial myocytes and 21 ventricular myocytes examined. HCN4 coexpressed with the MinK-related peptide 1 (MiRP1) β-subunit in CHO cells generated large I f currents. In contrast, HCN3 (+MiRP1) failed to produce I f in the same expression system. Cs + (2 mM), which blocked 84 ± 12% of the native I f , reversibly reduced f H 19.2 ± 3.6% of the excised multicellular pacemaker tissue from 53 ± 5 to 44 ± 5 beats/min ( P < 0.05). However, this effect was probably due to the reduction of I Kr , which was also inhibited (63.5 ± 4.6%) by Cs + These results strongly suggest that f H regulation in the brown trout heart is largely independent on I f . Copyright © 2017 the American Physiological Society.

Troponin T elevation after permanent pacemaker implantation.

PubMed

Chen, Xueying; Yu, Ziqing; Bai, Jin; Hu, Shulan; Wang, Wei; Qin, Shengmei; Wang, Jingfeng; Sun, Zhe; Su, Yangang; Ge, Junbo

2017-08-01

The objective of the study is to study the incidence, significance, and factors associated with cardiac troponin T (CTNT) elevation after pacemaker implantation. Three hundred seventy-four patients (104 single-chamber pacemakers or ICD, 243 dual-chamber pacemakers, and 27 cardiac resynchronization therapy/cardiac resynchronization therapy defibrillator) who had normal levels of CTNT at baseline and underwent implantation of a permanent pacemaker system were included in this study. Serum levels of CTNT were measured at baseline, 6 and 24 h after the implantation procedure. The median of CTNT levels increased from 0.012 ng/mL at baseline to 0.032 and 0.019 ng/mL at 6 and 24 h after the procedure, respectively (all p < 0.0001). Elevated CTNT levels were noted in 208 patients (55.6%) at 6 h after the implantation, among which 29 patients (7.8%) had CTNT levels exceeding the range of minimal myocardial damage (>0.09 ng/mL). After 1-year follow-up, the incidence of complications including dislodgement of the lead, pocket infection, pneumothorax, hemothorax, and vein thrombus and cardiac outcomes including hospitalization of heart failure, coronary artery disease, arrhythmia, and cardiovascular mortality was not significantly different between the normal and elevated CTNT groups at 6 h after the procedure. By logistic regression analysis, gender, N-terminal pro-B type natriuretic peptide (NT-pro-BNP) at baseline, left ventricular ejection fractions (LVEF), estimated glomerular filtration rate (eGFR), and fluoroscopy time were independently associated with CTNT elevation after adjusted for age, pacemaker types, right ventricle lead location (RVA or RVOT), heart function, and left ventricular end systolic dimension. Pacemaker implantation was found to be accompanied with CTNT elevation in 55.6% of the patients at 6 h after the procedure, and its kinetics were fast, which might not be related to the complications and adverse cardiac outcomes within 1 year of follow-up. Moreover, gender, NT-pro-BNP at baseline, LVEF, eGFR, and fluoroscopy time were found to be independent predictors of CTNT elevation.

Permanent epicardial pacing in pediatric patients: 12-year experience at a single center.

PubMed

Kwak, Jae Gun; Kim, Soo-Jin; Song, Jin Young; Choi, Eun Young; Lee, Sang Yoon; Shim, Woo Sup; Lee, Chang-Ha; Lee, Cheul; Park, Chun Soo

2012-02-01

Permanent cardiac pacing is not often done in children, and when done is usually accomplished through epicardial pacing. We reviewed a 12-year experience with the implantation of epicardial pacemakers by our clinical group. Fifty-three patients who underwent their first implantation of an epicardial pacemaker before the age of 18 years and between 1997 and 2009 were included in our study. The mean age of the patients at the time of first pacemaker implantation was 5.7±4.8 years. Indications for pacemaker implantation included postoperative or congenital atrioventricular block and sinus node dysfunction. The patients underwent 105 operations for the replacement of pacemaker pulse generators and 75 operations for the replacement of pacemaker leads. The most commonly used generator mode was the rate-responsive accelerometer-based (DDDR) mode, which was used in 40.9% of the patients. We used more non-steroid-eluting leads (70.1%) than steroid-eluting leads (29.1%). The overall duration of follow-up in the study was 8.0±4.5 years (range, 2.1 months to approximately 17.0 years). Freedom from the need for generator replacement was 98.0%, 60.7%, and 11.1% at 1, 5, and 8 years, respectively. A tendency toward early generator exhaustion was observed among younger patients (p=0.058). The generator mode used for pacing did not significantly affect generator longevity. Freedom from the need for lead replacement was 98.3%, 83.8%, and 63.6% at 1, 5, and 10 years, respectively. The mean longevity of the leads used in the study was 10.8±0.8 years. Neither patient age at the time of lead implantation nor type of lead significantly affected lead longevity. Lead longevity was sufficiently long and did not vary significantly according to type of lead. Generator longevity was not affected by lead type, generator mode, or patient age at the time of pacemaker implantation. Copyright © 2012 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

A model of optical trapping cold atoms using a metallic nano wire with surface plasmon effect

NASA Astrophysics Data System (ADS)

Thi Phuong Lan, Nguyen; Thi Nga, Do; Viet, Nguyen Ai

2016-06-01

In this work, we construct a new model of optical trapping cold atoms with a metallic nano wire by using surface plasmon effect generated by strong field of laser beams. Using the skin effect, we send a strong oscillated electromagnetic filed through the surface of a metallic nano wire. The local field generated by evanescent effect creates an effective attractive potential near the surface of metallic nano wires. The consideration of some possible boundary and frequency conditions might lead to non-trivial bound state solution for a cold atom. We discus also the case of the laser reflection optical trap with shell-core design, and compare our model with another recent schemes of cold atom optical traps using optical fibers and carbon nanotubes.

Myopotential inhibition of a bipolar pacemaker caused by electrode insulation defect.

PubMed Central

Amikam, S; Peleg, H; Lemer, J; Riss, E

1977-01-01

A patient is described in whom myopotentials orginating from the anterior abdominal wall muscle suppressed the implanted demand pacemaker despite its bipolar mode of action. This phenomenon was shown by simultaneous recording of the electrocardiogram the electromyogram. At operation, a defect in the insulation of a previously repaired epicardial electrode was found lying in close proximity to these muscles. After repair of the insulation defect, normal pacemaker function was restored. It is suggested that the myopotentials leaked into the pacing system through the insulation defect, thereby suppressing the demand unit, which maintained its bipolar mode of pacing throughout. Images PMID:145229

Medial subclavicular musculotendinous complex and insulation break: Rare cause of late pacemaker lead malfunction

PubMed Central

Bhattacharyya, Pranab Jyoti; Agrawal, Shweta; Barkataky, Jogesh Chandra; Bhattacharyya, Anjan Kumar

2015-01-01

Insulation break in a permanent pacemaker lead is a rare long-term complication. We describe an elderly male with a VVIR pacemaker, who presented with an episode of presyncope more than 3 years after the initial implantation procedure, attributed to insulation break possibly caused by lead entrapment in components of the medial subclavicular musculotendinous complex (MSMC) and repeated compressive damage over time during ipsilateral arm movement requiring lead replacement. The differential diagnosis of a clinical presentation when pacing stimuli are present with failure to capture and the role of the MSMC in causing lead damage late after implantation are discussed. PMID:26995445

Failure of communication and capture: The perils of temporary unipolar pacing system.

PubMed

Sahinoglu, Efe; Wool, Thomas J; Wool, Kenneth J

2015-06-01

We present a case of a patient with pacemaker dependence secondary to complete heart block who developed loss of capture of her temporary pacemaker. Patient developed torsades de pointes then ventricular fibrillation, requiring CPR and external cardioversion. After patient was stabilized, it was noticed that loss of capture of pacemaker corresponded with nursing care, when the pulse generator was lifted off patient׳s chest wall, and that patient׳s temporary pacing system had been programmed to unipolar mode without knowledge of attending cardiologist. This case highlights the importance of communication ensuring all caregivers are aware of mode of the temporary pacing system.

Regulation of Drosophila Brain Wiring by Neuropil Interactions via a Slit-Robo-RPTP Signaling Complex.

PubMed

Oliva, Carlos; Soldano, Alessia; Mora, Natalia; De Geest, Natalie; Claeys, Annelies; Erfurth, Maria-Luise; Sierralta, Jimena; Ramaekers, Ariane; Dascenco, Dan; Ejsmont, Radoslaw K; Schmucker, Dietmar; Sanchez-Soriano, Natalia; Hassan, Bassem A

2016-10-24

The axonal wiring molecule Slit and its Round-About (Robo) receptors are conserved regulators of nerve cord patterning. Robo receptors also contribute to wiring brain circuits. Whether molecular mechanisms regulating these signals are modified to fit more complex brain wiring processes is unclear. We investigated the role of Slit and Robo receptors in wiring Drosophila higher-order brain circuits and identified differences in the cellular and molecular mechanisms of Robo/Slit function. First, we find that signaling by Robo receptors in the brain is regulated by the Receptor Protein Tyrosine Phosphatase RPTP69d. RPTP69d increases membrane availability of Robo3 without affecting its phosphorylation state. Second, we detect no midline localization of Slit during brain development. Instead, Slit is enriched in the mushroom body, a neuronal structure covering large areas of the brain. Thus, a divergent molecular mechanism regulates neuronal circuit wiring in the Drosophila brain, partly in response to signals from the mushroom body. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Microstructure study of direct laser fabricated Ti alloys using powder and wire

NASA Astrophysics Data System (ADS)

Wang, Fude; Mei, J.; Wu, Xinhua

2006-11-01

A compositionally graded material has been fabricated using direct laser fabrication (DFL). Two types of feedstock were fed simultaneously into the laser focal point, a burn resistant (BurTi) alloy Ti-25V-15Cr-2Al-0.2C powder and a Ti-6Al-4V wire. The local composition of the alloy was changed by altering the ratio of powder to wire by varying the feed rate of the powder whilst maintaining a fixed feed rate of wire-feed. For the range of compositions between about 20% and 100% BurTi only the beta phase was observed and the composition and lattice parameter varied monotonically. The grain size was found to be much finer in these functionally graded samples than in laser fabricated Ti64. Some samples were made using the wire-feed alone, where it was found that the microstructure is different from that found when using powder feed alone. The results are discussed in terms of the power requirements for laser fabrication of powder and wire samples.

Safety of Electromagnetic Articulography in Patients with Pacemakers and Implantable Cardioverter-Defibrillators

ERIC Educational Resources Information Center

Joglar, Jose A.; Nguyen, Carol; Garst, Diane M.; Katz, William F.

2009-01-01

Purpose: "Electromagnetic articulography (EMA)" uses a helmet to create alternating magnetic fields for tracking speech articulator movement. An important safety consideration is whether EMA magnetic fields interfere with the operation of speakers' pacemakers or implantable cardioverter-defibrillators (ICDs). In this investigation,…

Bioinstrumentation: A Project-Based Engineering Course

ERIC Educational Resources Information Center

Kyle, Aaron M.; Jangraw, David C.; Bouchard, Matthew B.; Downs, Matthew E.

2016-01-01

This paper presents the development, implementation, and assessment of a project-based Bioinstrumentation course. All course lectures and hands-on laboratory activities are related to a central project theme: a cardiac pacemaker. The students create a benchtop cardiac pacemaker by applying instrumentation knowledge acquired in the course to each…

21 CFR 870.3640 - Indirect pacemaker generator function analyzer.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Indirect pacemaker generator function analyzer. 870.3640 Section 870.3640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3640...