Sample records for cardiac pacemaker program

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

    SciTech Connect

    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; 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.

  2. 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

  3. Reuse of permanent cardiac pacemakers.

    PubMed Central

    Rosengarten, M D; Portnoy, D; Chiu, R C; Paterson, A K

    1985-01-01

    Cardiac pacemakers are part of a growing group of expensive implantable electronic devices; hospitals in which 100 pacemakers are implanted per year must budget over $300 000 for these devices. This cost represents a considerable burden to health care resources. Since the "life-span" of modern pacemakers often exceeds that of the patients who receive them, the recovery and reuse of these devices seems logical. Pacemakers can be resterilized and tested with current hospital procedures. Reuse should be acceptable under Canadian law, but the manner in which the pacemakers are recovered and the patients selected should follow careful guidelines. Every patient should provide written informed consent before receiving a recovered pacemaker. Properly executed, reuse of pacemakers should provide a high level of health care while maintaining or reducing the cost of these devices. PMID:4016637

  4. 21 CFR 870.5550 - External transcutaneous cardiac pacemaker (noninvasive).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 false External transcutaneous cardiac pacemaker (noninvasive). 870.5550...870.5550 External transcutaneous cardiac pacemaker (noninvasive). (a) Identification. An external transcutaneous cardiac pacemaker (noninvasive) is a...

  5. 21 CFR 870.5550 - External transcutaneous cardiac pacemaker (noninvasive).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 false External transcutaneous cardiac pacemaker (noninvasive). 870.5550...870.5550 External transcutaneous cardiac pacemaker (noninvasive). (a) Identification. An external transcutaneous cardiac pacemaker (noninvasive) is a...

  6. 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.

  7. Lithium iodide cardiac pacemakers: initial clinical experience.

    PubMed Central

    Burr, L. H.

    1976-01-01

    A new long-life cardiac pacemaker pulse generator powered by a lithium iodide fuel cell was introduced in Canada in 1973. The compact, hermetically sealed unit is easily implanted and reliable, has excellent patient acceptance and has an anticipated battery life of almost 14 years. Among 105 patients who received a lithium iodide pacemaker, complications occurred in 18. The lithium iodide pacemaker represents a significant advance in pacemaker generator technology and is recommended for long-term cardiac pacing; the manufacturer guarantees the pulse generator for 6 years. Images FIG. 1 PMID:974965

  8. Pacemaker interactions induce reentrant wave dynamics in engineered cardiac culture

    NASA Astrophysics Data System (ADS)

    Borek, Bart?omiej; Shajahan, T. K.; Gabriels, James; Hodge, Alex; Glass, Leon; Shrier, Alvin

    2012-09-01

    Pacemaker interactions can lead to complex wave dynamics seen in certain types of cardiac arrhythmias. We use experimental and mathematical models of pacemakers in heterogeneous excitable media to investigate how pacemaker interactions can be a mechanism for wave break and reentrant wave dynamics. Embryonic chick ventricular cells are cultured invitro so as to create a dominant central pacemaker site that entrains other pacemakers in the medium. Exposure of those cultures to a potassium channel blocker, E-4031, leads to emergence of peripheral pacemakers that compete with each other and with the central pacemaker. Waves emitted by faster pacemakers break up over the slower pacemaker to form reentrant waves. Similar dynamics are observed in a modified FitzHugh-Nagumo model of heterogeneous excitable media with two distinct sites of pacemaking. These findings elucidate a mechanism of pacemaker-induced reentry in excitable media.

  9. A new multiprogrammable isotopic powered cardiac pacemaker

    SciTech Connect

    Smyth, N.P.; Purdy, D.L.; Sager, D.; Keshishian, J.M.

    1982-09-01

    A new multiprogrammable, isotopic-powered cardiac pacemaker was implanted in six patients as a custom device. Five were initial implants and one was a replacement. The patients were studied for up to two years. In five of the six cases it was found advantageous to change one of the programmable parameters. Multiprogrammability is obviously as important in an isotopic pulse generator as in a lithium unit, if not more so, because of the unit's greater longevity. Further studies are continuing in an FDA approved clinical trial.

  10. Sexual dimorphism in the complexity of cardiac pacemaker activity

    NSDL National Science Digital Library

    Terry B. Kuo (Tzu Chi Buddhist General Hospital Department of Neurology)

    2007-10-03

    Journal article titled "Sexual Dimorphism in the Complexity of Cardiac Pacemaker Activity" from The American Journal of PhysiologyÂ?Heart and Circulatory Physiology, by Terry B. J. Kuo, and Cheryl C. H. Yang.

  11. Proton Beam Therapy Interference With Implanted Cardiac Pacemakers

    SciTech Connect

    Oshiro, Yoshiko [Department of Radiation Oncology, University of Tsukuba, Ibaraki (Japan)], E-mail: ooyoshiko@pmrc.tsukuba.ac.jp; Sugahara, Shinji [Department of Radiation Oncology, University of Tsukuba, Ibaraki (Japan); Noma, Mio; Sato, Masato; Sakakibara, Yuzuru [Department of Cardiovascular Surgery, University of Tsukuba, Ibaraki (Japan); Sakae, Takeji [Proton Medical Research Center, University of Tsukuba, Ibaraki (Japan); Hayashi, Yasutaka [Department of Radiation Oncology, University of Tsukuba, Ibaraki (Japan); Nakayama, Hidetsugu; Tsuboi, Koji; Fukumitsu, Nobuyoshi [Department of Radiation Oncology, University of Tsukuba, Ibaraki (Japan); Proton Medical Research Center, University of Tsukuba, Ibaraki (Japan); Kanemoto, Ayae [Department of Radiation Oncology, University of Tsukuba, Ibaraki (Japan); Hashimoto, Takayuki [Division of Radiation Oncology, Shizuoka Cancer Center Hospital, Shizuoka (Japan); Tokuuye, Koichi [Department of Radiation Oncology, University of Tsukuba, Ibaraki (Japan); Proton Medical Research Center, University of Tsukuba, Ibaraki (Japan)

    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 before 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.

  12. SHOX2 Overexpression Favors Differentiation of Embryonic Stem Cells into Cardiac Pacemaker Cells, Improving Biological Pacing Ability

    PubMed Central

    Ionta, Vittoria; Liang, Wenbin; Kim, Elizabeth H.; Rafie, Reza; Giacomello, Alessandro; Marbán, Eduardo; Cho, Hee Cheol

    2014-01-01

    Summary When pluripotency factors are removed, embryonic stem cells (ESCs) undergo spontaneous differentiation, which, among other lineages, also gives rise to cardiac sublineages, including chamber cardiomyocytes and pacemaker cells. Such heterogeneity complicates the use of ESC-derived heart cells in therapeutic and diagnostic applications. We sought to direct ESCs to differentiate specifically into cardiac pacemaker cells by overexpressing a transcription factor critical for embryonic patterning of the native cardiac pacemaker (the sinoatrial node). Overexpression of SHOX2 during ESC differentiation upregulated the pacemaker gene program, resulting in enhanced automaticity in vitro and induced biological pacing upon transplantation in vivo. The accentuated automaticity is accompanied by temporally evolving changes in the effectors and regulators of Wnt signaling. Our findings provide a strategy for enriching the cardiac pacemaker cell population from ESCs. PMID:25533636

  13. Generation of murine cardiac pacemaker cell aggregates based on ES-cell-programming in combination with Myh6-promoter-selection.

    PubMed

    Rimmbach, Christian; Jung, Julia J; David, Robert

    2015-01-01

    Treatment of the "sick sinus syndrome" is based on artificial pacemakers. These bear hazards such as battery failure and infections. Moreover, they lack hormone responsiveness and the overall procedure is cost-intensive. "Biological pacemakers" generated from PSCs may become an alternative, yet the typical content of pacemaker cells in Embryoid Bodies (EBs) is extremely low. The described protocol combines "forward programming" of murine PSCs via the sinus node inducer TBX3 with Myh6-promoter based antibiotic selection. This yields cardiomyocyte aggregates consistent of >80% physiologically functional pacemaker cells. These "induced-sinoatrial-bodies" ("iSABs") are spontaneously contracting at yet unreached frequencies (400-500 bpm) corresponding to nodal cells isolated from mouse hearts and are able to pace murine myocardium ex vivo. Using the described protocol highly pure sinus nodal single cells can be generated which e.g. can be used for in vitro drug testing. Furthermore, the iSABs generated according to this protocol may become a crucial step towards heart tissue engineering. PMID:25742394

  14. Materials aspects of implantable cardiac pacemaker leads.

    PubMed

    Bruck, S D; Mueller, E P

    1988-01-01

    The reliability of the leads of the entire pacemaker system is vital as the risks of failure include: (1) loss of pacing due to the deterioration of the polymeric insulator in the physiological environment; (2) thromboembolism due to inadequate blood compatibility of the insulator; (3) tissue reactions at the electrode/tissue interface; (4) general foreign body rejection phenomena; (5) perforation of the leads; and (6) excessive stress applied by sutures causing abrasion and stress cracking. Although silicone has been used widely, some years ago Pellethane (a segmented polyetherurethane-urea) has been introduced as an alternate lead insulator, chiefly because it can be extruded using additives into smooth and thin tubes. The additives (antioxidants), extrusion aids, and low molecular weight polymer chains (oligomers) together represent up to approximately 8% by weight of leachables, depending on the extraction medium. The in vivo degradation of Pellethane is biologic in nature and is most likely associated with the absorption and premeation of body fluids from the surrounding physiologic environment leading to stress cracking via the formation of microvoids. Thermally and biologically unstable biuret and allophonate groups in this polyurethane, exposure of the polymer to high extrusion temperatures, and stresses created within the polymer also play key roles in the degradation process. In the case of electrodes, some corrosion can occur even with noble metals and ions formed with the involvement of penetrating body fluids which may combine with the urethane and/or urea groups of the polyurethane, leading to its further degradation in vivo. The totality of the situation indicates a need for the development of a standard guideline for the uniform and consistent pre-clinical testing and evaluation of new materials and fabrication processes of implantable pacemaker leads. Such guidelines should take into consideration, among others, the physiological environment, species-differences between test animals and humans, and observe reliable statistical interpretations based on sufficient data. PMID:3285160

  15. PP2 prevents ?-adrenergic stimulation of cardiac pacemaker activity.

    PubMed

    Huang, Jianying; Lin, Yen-Chang; Hileman, Stan; Martin, Karen H; Hull, Robert; Yu, Han-Gang

    2014-06-01

    One of the main strategies for cancer therapy is to use tyrosine kinase inhibitors for inhibiting tumor proliferation. Increasing evidence has demonstrated the potential risks of cardiac arrhythmias (such as prolonged QT interval) of these drugs. We report here that a widely used selective inhibitor of Src tyrosine kinases, 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP2), can inhibit and prevent ?-adrenergic stimulation of cardiac pacemaker activity. First, in dissected rat sinus node, PP2 inhibited and prevented the isoproterenol-induced increase of spontaneous beating rate. Second, in isolated rat sinus node myocytes, PP2 suppressed the hyperpolarization-activated "funny" current (traditionally called cardiac pacemaker current, I(f)) by negatively shifting the activation curve and decelerating activation kinetics. Third, in isolated rat sinus node myocytes, PP2 decreased the Src kinase activity, the cell surface expression, and tyrosine phosphorylation of hyperpolarization-activated, cyclic nucleotide-modulated channel 4 (HCN4) channel proteins. Finally, in human embryonic kidney 293 cells overexpressing recombinant human HCN4 channels, PP2 reversed the enhancement of HCN4 channels by isoproterenol and inhibited 573x, a cyclic adenosine momophosphate-insensitive human HCN4 mutant. These results demonstrated that inhibition of Src kinase activity in heart by PP2 decreased and prevented ?-adrenergic stimulation of cardiac pacemaker activity. These effects are mediated, at least partially, by a cAMP-independent attenuation of channel activity and cell surface expression of HCN4, the main channel protein that controls the heart rate. PMID:24566462

  16. A Simulink Hybrid Heart Model for Quantitative Verification of Cardiac Pacemakers

    E-print Network

    Oxford, University of

    Mereacre Department of Computer Science University of Oxford, UK ABSTRACT We develop a novel hybrid heartA Simulink Hybrid Heart Model for Quantitative Verification of Cardiac Pacemakers Taolue Chen model in Simulink that is suitable for quantitative verification of implantable cardiac pacemakers

  17. Conceptual Design of GaN Betavoltaic Battery using in Cardiac Pacemaker

    Microsoft Academic Search

    M. Mohamadian; S. A. H. Feghhi; H. Afarideh

    Pacemaker is an electronic biomedical device which stimulates and regulates or amplify the human heartbeat by delivering weak electrical pulses to the cardiac muscle at regular intervals when its natural regulating mechanisms break down. The purpose of the present work is to introduce a kind of low power Betavoltaic battery using in nuclear powered cardiac pacemakers which have higher efficiency

  18. Clinical utility of a magnetic resonance-conditional pacemaker in a patient with cardiac sarcoidosis.

    PubMed

    Ishibashi, Kazuya; Takeda, Mitsuo; Yamahara, Yasuhiro

    2013-01-01

    We herein present a case of cardiac sarcoidosis with atrioventricular (AV) block that was evaluated using magnetic resonance imaging (MRI) before and after pacemaker implantation. An echocardiogram showed wall thinning in the basal septum. MRI showed late gadolinium enhancement in the interventricular septum and right ventricle. Fluorine-18-fluorodeoxyglucose positron emission tomography (PET) demonstrated abnormal uptake in the same area. An MR-conditional pacemaker was implanted to treat AV block. Steroid treatment resulted in the remission of the cardiac lesions and AV block, as confirmed by PET and MRI. MR-conditional pacemakers are thus considered to have great advantages in treating cardiac sarcoidosis with AV block. PMID:23774544

  19. 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.

  20. Experimental and theoretical investigation of implantable cardiac pacemaker exposed to low frequency magnetic field.

    PubMed

    Babouri, A; Hedjeidj, A; Guendouz, L

    2009-04-01

    This paper presents in vitro investigation of an implantable cardiac pacemaker exposed to low frequency magnetic fields. The method used in this study is based on the interaction by inductive coupling through the loop formed by the pacemaker and its loads and the surrounding medium. This interaction results in an induced electromotive force between the terminals of the pacemaker, which can potentially disturb its operation. The studied frequencies are 50/60 Hz and 10/25 kHz. The experimental tests were carried out on several cardiac pacemakers, single chamber, and dual chamber. The results show a window effect of the detection circuits of cardiac pacemakers for the four studied frequencies. The modelling of the test bed requires studying the effects of the induced currents generated by the application of a magnetic field. Analytical calculations and Numerical simulations were carried out. We modelled the interactions of the magnetic field with a simplified representation of pacemaker embedded in the medium. The comparison of the results in the air and in vitro enabled us to make an equivalent electric model. The results obtained in experimental and theoretical studies allowed us to validate the test bed. The method applied is valid for other medical implants such as cardiac defibrillators, implant hearing aids system...etc. PMID:19125341

  1. A model of cardiac tissue as a conductive system with interacting pacemakers and refractory time

    E-print Network

    Alexander Loskutov; Sergei Rybalko; Ekaterina Zhuchkova

    2002-12-10

    A model of the heart tissue as a conductive system with two interacting pacemakers and a refractory time, is proposed. In the parametric space of the model the phase locking areas are investigated in detail. Obtained results allow us to predict the behaviour of excitable systems with two pacemakers depending on the type and intensity of their interaction and the initial phase. Comparison of the described phenomena with intrinsic pathologies of cardiac rhythms is presented.

  2. Implanted cardiac pacemaker pulses as recorded from the body surface.

    PubMed

    Luo, Shen; Johnston, Paul; Macfarlane, Peter W

    2012-01-01

    This study investigates the characteristics of contemporary pacemaker pulses as recorded from the body surface. Twelve-lead paced ECGs from 140 patients (68 ± 12 years, 71% males) were collected at 32,000 samples per second. Pacer pulses were manually annotated based on the high-sampling rate data stream. The results show that durations of the various pulses are stable, while amplitudes exhibit large variations. Also, more than 50% of pulses have either durations <0.5 ms or amplitudes <2 mV, which are the AAMI/IEC thresholds for detection and marking of pacemaker pulses on an ECG report. Therefore the current standards for pacemaker pulse detection are not fit for purpose and require to be updated. Further, this study suggests that a high-sampling rate database should be used as a standard test for pacemaker annotation and detection from body surface ECGs. PMID:23034404

  3. Strategy for Safe Performance of Extrathoracic Magnetic Resonance Imaging at 1.5 Tesla in the Presence of Cardiac Pacemakers in Non-Pacemaker-Dependent Patients A Prospective Study With 115 Examinations

    Microsoft Academic Search

    Torsten Sommer; Claas P. Naehle; Alexander Yang; Volkert Zeijlemaker; Matthias Hackenbroch; Alexandra Schmiedel; Carsten Meyer; Katharina Strach; Dirk Skowasch; Christian Vahlhaus; Harold Litt; Hans Schild

    2011-01-01

    Background—The purpose of the present study was to evaluate a strategy for safe performance of extrathoracic magnetic resonance imaging (MRI) in non-pacemaker-dependent patients with cardiac pacemakers. Methods and Results—Inclusion criteria were presence of a cardiac pacemaker and urgent clinical need for an MRI examination. Pacemaker-dependent patients and those requiring examinations of the thoracic region were excluded. The study group consisted

  4. Benefits of the advances in cardiac pacemaker technology.

    PubMed

    Shakespeare, C F; Camm, A J

    1992-08-01

    Pacemaker technology has expanded rapidly in the last thirty years. Each phase of development has been marked by both improvements in clinical benefit and disadvantageous interactions of physiology and technology. Each phase of development has led to smaller, more reliable devices with greater programmability. Advances in generator technology and battery design have increased longevity of devices. The first devices used asynchronous pacing which had a significant effect in reducing the mortality of surgically induced complete heart block. Ventricular demand pacemakers overcame the problems of asynchronous competitive pacing, but exposed the pacemaker syndrome. Atrioventricular sequential pacing restored atrioventricular synchrony, resulting in hemodynamic improvement, but created the phenomenon of pacemaker-mediated tachycardia. Alternative dual chamber modes and algorithms have largely resolved this. Adaptive-rate devices have been of benefit to patients with chronotropic incompetence, and are now incorporating an increasing variety of biosensors. Almost all the problems of pacing have been overcome, but the increasing complexity of pacemaker technology is now a major limitation to its proper use. PMID:1499189

  5. Calculation of the induced voltage at the terminals of cardiac pacemakers submitted to conducted disturbances.

    PubMed

    Andretzko, J P; Hedjiedj, A; Guendouz, L

    2007-04-01

    This paper presents a method of numerical simulation based on the admittance method which allows us to calculate the induced tension at the terminals of a cardiac pacemaker subjected to conducted disturbances. The physical model used for simulation is an experimental test bed that makes it possible to study in vitro the behavior of pacemakers subjected to electromagnetic disturbances. The studied frequencies correspond to domestic and industrial applications of electricity (50 Hz-500 kHz). The experimental tests are carried out with two different single-chamber pacemakers implanted in a tissue-equivalent phantom and correlated to tests performed in air (without the phantom). Results obtained by numerical simulation are in good agreement with experimental values and that allows us to validate the computer model. Numerical results are used to determine the transfer function between the signal source and the signal induced between the distal lead tip and the case of the implanted device. PMID:17395992

  6. Pulsed Nd:YAG laser welding of cardiac pacemaker batteries with reduced heat input

    Microsoft Academic Search

    P. W. Fuerschbach; D. A. Hinkley

    1997-01-01

    The effects of Nd:YAG laser beam welding process parameters on the resulting heat input in 304L stainless steel cardiac pacemaker batteries have been studied. By careful selection of process parameters, the results can be used to reduce temperatures near glass-to-metal seals and assure hermeticity in laser beam welding of high reliability components. Three designed response surface experiments were used to

  7. Self-powered cardiac pacemaker enabled by flexible single crystalline PMN-PT piezoelectric energy harvester.

    PubMed

    Hwang, Geon-Tae; Park, Hyewon; Lee, Jeong-Ho; Oh, SeKwon; Park, Kwi-Il; Byun, Myunghwan; Park, Hyelim; Ahn, Gun; Jeong, Chang Kyu; No, Kwangsoo; Kwon, HyukSang; Lee, Sang-Goo; Joung, Boyoung; Lee, Keon Jae

    2014-07-23

    A flexible single-crystalline PMN-PT piezoelectric energy harvester is demonstrated to achieve a self-powered artificial cardiac pacemaker. The energy-harvesting device generates a short-circuit current of 0.223 mA and an open-circuit voltage of 8.2 V, which are enough not only to meet the standard for charging commercial batteries but also for stimulating the heart without an external power source. PMID:24740465

  8. Requirement of neuronal- and cardiac-type sodium channels for murine sinoatrial node pacemaking

    PubMed Central

    Lei, Ming; Jones, Sandra A; Liu, Jie; Lancaster, Matthew K; Fung, Simon S-M; Dobrzynski, Halina; Camelliti, Patrizia; Maier, Sebastian K G; Noble, Denis; Boyett, Mark R

    2004-01-01

    The majority of Na+ channels in the heart are composed of the tetrodotoxin (TTX)-resistant (KD, 2–6 ?m) Nav1.5 isoform; however, recently it has been shown that TTX-sensitive (KD, 1–10 nm) neuronal Na+ channel isoforms (Nav1.1, Nav1.3 and Nav1.6) are also present and functionally important in the myocytes of the ventricles and the sinoatrial (SA) node. In the present study, in mouse SA node pacemaker cells, we investigated Na+ currents under physiological conditions and the expression of cardiac and neuronal Na+ channel isoforms. We identified two distinct Na+ current components, TTX resistant and TTX sensitive. At 37°C, TTX-resistant iNa and TTX-sensitive iNa started to activate at ??70 and ??60 mV, and peaked at ?30 and ?10 mV, with a current density of 22 ± 3 and 18 ± 1 pA pF?1, respectively. TTX-sensitive iNa inactivated at more positive potentials as compared to TTX-resistant iNa. Using action potential clamp, TTX-sensitive iNa was observed to activate late during the pacemaker potential. Using immunocytochemistry and confocal microscopy, different distributions of the TTX-resistant cardiac isoform, Nav1.5, and the TTX-sensitive neuronal isoform, Nav1.1, were observed: Nav1.5 was absent from the centre of the SA node, but present in the periphery of the SA node, whereas Nav1.1 was present throughout the SA node. Nanomolar concentrations (10 or 100 nm) of TTX, which block TTX-sensitive iNa, slowed pacemaking in both intact SA node preparations and isolated SA node cells without a significant effect on SA node conduction. In contrast, micromolar concentrations (1–30 ?m) of TTX, which block TTX-resistant iNa as well as TTX-sensitive iNa, slowed both pacemaking and SA node conduction. It is concluded that two Na+ channel isoforms are important for the functioning of the SA node: neuronal (putative Nav1.1) and cardiac Nav1.5 isoforms are involved in pacemaking, although the cardiac Nav1.5 isoform alone is involved in the propagation of the action potential from the SA node to the surrounding atrial muscle. PMID:15254155

  9. 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.

  10. The beat goes on: Cardiac pacemaking in extreme conditions.

    PubMed

    Wilson, Christopher M; Cox, Georgina K; Farrell, Anthony P

    2015-08-01

    In order for an animal to survive, the heart beat must go on in all environmental conditions, or at least restart its beat. This review is about maintaining a rhythmic heartbeat under the extreme conditions of anoxia (or very severe hypoxia) and high temperatures. It starts by considering the primitive versions of the protein channels that are responsible for initiating the heartbeat, HCN channels, divulging recent findings from the ancestral craniate, the Pacific hagfish (Eptatretus stoutii). It then explores how a heartbeat can maintain a rhythm, albeit slower, for hours without any oxygen, and sometimes without autonomic innervation. It closes with a discussion of recent work on fishes, where the cardiac rhythm can become arrhythmic when a fish experiences extreme heat. PMID:25178563

  11. 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

  12. Improved quality of life after treatment of prolonged asystole during breath holding spells with a cardiac pacemaker

    PubMed Central

    Kolterer, Bruno; Gebauer, Roman Antonin; Janousek, Jan; Dähnert, Ingo; Riede, Frank Thomas; Paech, Christian

    2015-01-01

    Objectives: To validate the physical and psychological effectiveness of cardiac pacing in pediatric patients with breath-holding spells (BHS) and prolonged asystole. Materials and Methods: The records and clinical data of all the patients with BHS who presented to our center in the period of 2001–2013 were reviewed. All patients who received cardiac pacemaker implantation for prolonged asystole during BHS were included. In addition, the parents were asked to fill out a standardized quality of life (QOL) questionnaire. Results: Seven patients were identified. The mean onset of symptoms was 7 month (1–12 months) of age, documented asystole was 12–21 seconds, and a permanent cardiac pacemaker device was implanted at a mean age of 23 months (8 months–3.9 years). No pacemaker related adverse events were recorded. Follow up showed immediate resolution from spells in four cases (4/7). Two patients (2/7) showed significant reduction of frequency and severity of spells, with complete elimination of loss of consciousness (LOC). One patient (1/7) with an additional neurologic disorder continued to have minor pallid BHS and eventually switched from pallid to cyanotic spells without further detection of bradycardia or asystole in holter examination. QOL questionnaire revealed significant reduction in subjective stress levels of patients (P = 0.012) and parents (P = 0.007) after pacemaker implantation. Conclusion: Cardiac pacing using appropriate pacemaker settings seems effective in the prevention of LOC and reduction of the frequency of BHS. Our results imply a reduction of subjective stress levels of patients and parents as well as an increased quality of everyday life. After all, randomized controlled trials of the influence of cardiac pacemaker implantation on subjective stress levels in patients with BHS are needed.

  13. The interference threshold of unipolar cardiac pacemakers in extremely low frequency magnetic fields.

    PubMed

    Scholten, A; Silny, J

    2001-01-01

    The effective induction loop area of implanted cardiac pacemaker (CPM) systems in magnetic fields was determined. The results were verified in a tank model placed in the centre of a Helmholtz-coil-arrangement. Both a left and a right pectorally implanted unipolar dual chamber CPM system were simulated. On this basis and with the results of benchmark-tests the interference thresholds for a collection of modern CPMs in extremely low frequency (ELF) magnetic fields were estimated. The investigations clearly showed that there are two loops, the CPM-lead-tissue-loop and the body loop, responsible for the magnitude of the disturbance voltage on the input of a cardiac pacemaker. The effective induction loop areas rangedfrom 100 to 221 cm2. For a left pectorally implanted, atrially controlled CPM system the interference thresholds for the magnetic induction lay between 16 and 552 micro T (RMS) for frequencies of the magneticfield between 10 and 250 Hz. Thus, there is a limited possibility for an interference of implanted CPM by ELF magnetic fields in everyday life. PMID:11695658

  14. Immediate and 12 months follow up of function and lead integrity after cranial MRI in 356 patients with conventional cardiac pacemakers

    PubMed Central

    2014-01-01

    Background Conventional cardiac pacemakers are still often regarded as a contraindication to magnetic resonance imaging (MRI). We conducted this study to support the hypothesis that it is safe to scan patients with cardiac pacemakers in a 1.5 Tesla MRI, if close supervision and monitoring as well as adequate pre- and postscan programming is provided. Methods We followed up 356 patients (age 61.3?±?9.1 yrs., 229 men) with single (n?=?132) or dual chamber (n?=?224) cardiac pacemakers and urgent indication for a cranial MRI for 12 months. The scans were performed at 1.5T. During the scan patients were monitored with a 3-lead ECG and pulse oximetry. Prior to the scan pacemakers were programmed according to our own protocol. Results All 356 scans were completed without complications. No arrhythmias were induced, programmed parameters remained unchanged. No pacemaker dysfunction was identified. Follow-up examinations were performed immediately, 2 weeks, 2, 6, and 12 months after the scan. There was no significant change of pacing capture threshold (ventricular 0.9?±?0.4 V@0.4 ms, atrial 0.9?±?0.3 V@0.4 ms) immediately (ventricular 1.0?±?0.3 V@0.4 ms, atrial 0.9?±?0.4 V@0.4 ms) or at 12 months follow-up examinations (ventricular 0.9?±?0.2 V@0.4 ms, atrial 0.9?±?0.3 V@0.4 ms). There was no significant change in sensing threshold (8.0?±?4.0 mV vs. 8.1?±?4.2 mV ventricular lead, 2.0?±?0.9 mV vs. 2.1?±?1.0 mV atrial lead) or lead impedance (ventricular 584?±?179?? vs. 578?±?188??, atrial 534?±?176?? vs. 532?±?169??) after 12 months. Conclusions This supports the evidence that patients with conventional pacemakers can safely undergo cranial MRI in a 1.5T system with suitable preparation, supervision and precautions. Long term follow-up did not reveal significant changes in pacing capture nor sensing threshold. PMID:24903354

  15. Genetically engineered cardiac pacemaker: Stem cells transfected with HCN2 gene and myocytes—A model

    NASA Astrophysics Data System (ADS)

    Kanani, S.; Pumir, A.; Krinsky, V.

    2008-01-01

    One of the successfully tested methods to design genetically engineered cardiac pacemaker cells consists in transfecting a human mesenchymal stem cell (hMSC) with a HCN2 gene and connecting it to a myocyte. We develop and study a mathematical model, describing a myocyte connected to a hMSC transfected with a HCN2 gene. The cardiac action potential is described both with the simple Beeler Reuter model, as well as with the elaborate dynamic Luo Rudy model. The HCN2 channel is described by fitting electrophysiological records, in the spirit of Hodgkin Huxley. The model shows that oscillations can occur in a pair myocyte-stem cell, that was not observed in the experiments yet. The model predicted that: (1) HCN pacemaker channels can induce oscillations only if the number of expressed I channels is low enough. At too high an expression level of I channels, oscillations cannot be induced, no matter how many pacemaker channels are expressed. (2) At low expression levels of I channels, a large domain of values in the parameter space (n, N) exists, where oscillations should be observed. We denote N the number of expressed pacemaker channels in the stem cell, and n the number of gap junction channels coupling the stem cell and the myocyte. (3) The expression levels of I channels observed in ventricular myocytes, both in the Beeler Reuter and in the dynamic Luo Rudy models are too high to allow to observe oscillations. With expression levels below ˜1/4 of the original value, oscillations can be observed. The main consequence of this work is that in order to obtain oscillations in an experiment with a myocyte-stem cell pair, increasing the values of n, N is unlikely to be helpful, unless the expression level of I has been reduced enough. The model also allows us to explore levels of gene expression not yet achieved in experiments, and could be useful to plan new experiments, aimed at improving the robustness of the oscillations.

  16. Stochastic vagal modulation of cardiac pacemaking may lead to erroneous identification of cardiac ``chaos''

    NASA Astrophysics Data System (ADS)

    Zhang, J. Q.; Holden, A. V.; Monfredi, O.; Boyett, M. R.; Zhang, H.

    2009-06-01

    Fluctuations in the time interval between two consecutive R-waves of electrocardiogram during normal sinus rhythm may result from irregularities in the autonomic drive of the pacemaking sinoatrial node (SAN). We use a biophysically detailed mathematical model of the action potentials of rabbit SAN to quantify the effects of fluctuations in acetylcholine (ACh) on the pacemaker activity of the SAN and its variability. Fluctuations in ACh concentration model the effect of stochastic activity in the vagal parasympathetic fibers that innervate the SAN and produce varying rates of depolarization during the pacemaker potential, leading to fluctuations in cycle length (CL). Both the estimated maximal Lyapunov exponent and the noise limit of the resultant sequence of fluctuating CLs suggest chaotic dynamics. Apparently chaotic heart rate variability (HRV) seen in sinus rhythm can be produced by stochastic modulation of the SAN. The identification of HRV data as chaotic by use of time series measures such as a positive maximal Lyapunov exponent or positive noise limit requires both caution and a quantitative, predictive mechanistic model that is fully deterministic.

  17. Design of wavelet-based ECG detector for implantable cardiac pacemakers.

    PubMed

    Min, Young-Jae; Kim, Hoon-Ki; Kang, Yu-Ri; Kim, Gil-Su; Park, Jongsun; Kim, Soo-Won

    2013-08-01

    A wavelet Electrocardiogram (ECG) detector for low-power implantable cardiac pacemakers is presented in this paper. The proposed wavelet-based ECG detector consists of a wavelet decomposer with wavelet filter banks, a QRS complex detector of hypothesis testing with wavelet-demodulated ECG signals, and a noise detector with zero-crossing points. In order to achieve high detection accuracy with low power consumption, a multi-scaled product algorithm and soft-threshold algorithm are efficiently exploited in our ECG detector implementation. Our algorithmic and architectural level approaches have been implemented and fabricated in a standard 0.35 ?m CMOS technology. The testchip including a low-power analog-to-digital converter (ADC) shows a low detection error-rate of 0.196% and low power consumption of 19.02 ?W with a 3 V supply voltage. PMID:23893202

  18. Presentation of untreated systemic mastocytosis as recurrent, pulseless-electrical-activity cardiac arrests resistant to cardiac pacemaker.

    PubMed

    Butterfield, Joseph H; Weiler, Catherine R

    2014-01-01

    Recurrent, pulseless-electrical-activity (PEA) cardiac arrests were the novel presentation of untreated systemic mastocytosis in an 85-year-old woman who lacked cutaneous findings of mastocytosis. Despite prior implantation of a dual-chamber cardiac pacemaker 3 weeks previously for similar spells, she experienced a PEA arrest accompanied by flushing, increased urinary N-methylhistamine excretion and serum tryptase values on the day of presentation to our clinic. Bone marrow biopsy findings conducted to rule out breast cancer metastases showed 30% mast cell infiltration, aberrant expression of CD25 and a positive c-kit Asp816Val mutation. Treatment with a combination of H1 and H2 receptor blockers reduced flushing and eliminated hypotension. Maintenance medication included aspirin, cetirizine, ranitidine, montelukast, oral cromolyn sodium and an epinephrine autoinjector (as needed). At 6-month follow-up, the patient remained free of PEA arrests, flushing, or any clinical signs of mastocytosis or mast cell degranulation. PEA cardiac arrests may therefore be a presenting sign of untreated systemic mastocytosis. PMID:24335343

  19. Inhibition of cardiac pacemaker channel hHCN2 depends on intercalation of lipopolysaccharide into channel-containing membrane microdomains

    PubMed Central

    Klöckner, Udo; Rueckschloss, Uwe; Grossmann, Claudia; Matzat, Saskia; Schumann, Katja; Ebelt, Henning; Müller-Werdan, Ursula; Loppnow, Harald; Werdan, Karl; Gekle, Michael

    2014-01-01

    Depressed heart rate variability in severe inflammatory diseases can be partially explained by the lipopolysaccharide (LPS)-dependent modulation of cardiac pacemaker channels. Recently, we showed that LPS inhibits pacemaker current in sinoatrial node cells and in HEK293 cells expressing cloned pacemaker channels, respectively. The present study was designed to verify whether this inhibition involves LPS-dependent intracellular signalling and to identify structures of LPS responsible for pacemaker current modulation. We examined the effect of LPS on the activity of human hyperpolarization-activated cyclic nucleotide-gated channel 2 (hHCN2) stably expressed in HEK293 cells. In whole-cell recordings, bath application of LPS decreased pacemaker current (IhHCN2) amplitude. The same protocol had no effect on channel activity in cell-attached patch recordings, in which channels are protected from the LPS-containing bath solution. This demonstrates that LPS must interact directly with or close to the channel protein. After cleavage of LPS into lipid A and the polysaccharide chain, neither of them alone impaired IhHCN2, which suggests that modulation of channel activity critically depends on the integrity of the entire LPS molecule. We furthermore showed that ?-cyclodextrin interfered with LPS-dependent channel modulation predominantly via scavenging of lipid A, thereby abrogating the capability of LPS to intercalate into target cell membranes. We conclude that LPS impairs IhHCN2 by a local mechanism that is restricted to the vicinity of the channels. Furthermore, intercalation of lipid A into target cell membranes is a prerequisite for the inhibition that is suggested to depend on the direct interaction of the LPS polysaccharide chain with cardiac pacemaker channels. PMID:24366264

  20. 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

  1. Assessment of cardiac stroke volume in patients with implanted cardiac pacemaker using parametric electrical impedance tomography: a theoretical 2D study.

    PubMed

    Mhajna, Muhammad; Abboud, Shimon

    2013-05-01

    The present theoretical study examines the ability to estimate cardiac stroke volume (CSV) in patients with implanted cardiac pacemaker using parametric electrical impedance tomography (pEIT) in a 2D computerized model of the thorax. CSV is a direct indicator of the cardiac pumping efficiency. The commonly used methods for measuring CSV require the invasive procedure of right heart catheterization or use expensive imaging techniques (i.e., MRI). Hence, experience with these techniques for diagnosis and monitoring has been limited to hospitalized patients. In the present study, pEIT scheme was applied in a computerized 2D model of the human thorax with implanted cardiac device to determine the left ventricular (LV) volume at different cardiac cycle phases. The LV was simulated as a prolate ellipse with its axes' lengths as the reconstruction parameters while all other geometries and conductivity values remained constant. An optimization was carried out in order to ensure that the ellipse is the appropriate model for the LV at each cardiac cycle phase. LV volumes calculated by both the pEIT algorithm and the ellipsoid model are consistent. A high correlation (??=?0.99) between the true and reconstructed volumes was found. The SV calculation error was ?1%. The results suggest that the LV volume can be estimated using the pEIT method in a 2D computerized model, and that the method has the potential to be used for monitoring patients with implanted cardiac pacemaker. PMID:23606371

  2. Selective manipulation of neurohumoral control of the cardiac pacemaker by drugs given intrapericardially.

    PubMed

    Lew, M J; Ludbrook, J; Pavia, J M; Quail, A W; Rutter, P C

    1987-04-01

    A technique of intrapericardial administration of beta-adrenoceptor and muscarinic cholinergic receptor antagonist drugs has been tested in conscious rabbits. Intrapericardial propranolol or atenolol (50 micrograms/kg) had the same effect on isoprenaline heart rate dose-response curves and on the sympathetic component of the arterial baroreceptor-heart rate reflex as did conventional, 5-fold greater, intravenous doses of the drugs. The action of intrapericardial propranolol was attributable to its (-)isomer. Intrapericardial propranolol (50 micrograms/kg) had little effect on ventricular contractility. Plasma levels of propranolol and atenolol after intrapericardial administration were, respectively, 7- and 40-fold less than after the usual intravenous doses. Intrapericardial hyoscine methyl bromide (10 micrograms/kg) abolished baroreflex vagal effects on heart rate as effectively as did the conventional, 5-fold greater, intravenous dose. The duration of receptor blockade by both classes of drugs when given intrapericardially was at least 2 hr. We conclude that the rapid diffusion of beta-adrenoceptor and muscarinic cholinergic receptor blocking drugs from the pericardial sac to receptors on the sinoatrial cardiac pacemaker, and their prolonged actions, provides a useful technique for preventing the actions of the sympathetic and vagus nerves, and of circulating catecholamines, on the chronotropic functions of the heart. PMID:2884351

  3. Quantitative Verification of Implantable Cardiac Pacemakers Taolue Chen Marco Diciolla Marta Kwiatkowska Alexandru Mereacre

    E-print Network

    Oxford, University of

    the electrocardiogram model of Clifford et al, which generates realistic normal and abnormal heart beat behaviours a methodology for deriving the composition of the heart and the pacemaker, based on discretisation. The main correctness properties we consider include checking that the pacemaker corrects Bradycardia (slow heart beat

  4. Program Overview The Cardiac Sonography program prepares individuals to perform cardiac

    E-print Network

    Cheng, Mei-Fang

    and Physiology, Pathophysiology, Ultrasound Physics, Instrumentation and Applied Cardiac Sonography. ClinicalProgram Overview The Cardiac Sonography program prepares individuals to perform cardiac sonography hours. Program Description The Cardiac Sonography Program is located on the Scotch Plains campus

  5. Interference of programmed electromagnetic stimulation with pacemakers and automatic implantable cardioverter defibrillators.

    PubMed

    Gwechenberger, Marianne; Rauscha, Friedrich; Stix, Günter; Schmid, Gernot; Strametz-Juranek, Jeanette

    2006-07-01

    A commercially available magnetic therapy system, designed for clinical application as well as for private use without medical supervision, was examined with respect to its potential for causing electromagnetic interference with implantable pacemakers (PMs) and automatic implantable cardioverter defibrillators (AICDs). A sample of 15 PMs and 5 AICDs were experimentally investigated. Each of the implants was realistically positioned in a homogeneous, electrically passive torso phantom and exposed to the magnetic fields of the system's applicators (whole body mat, cushion, and bar applicator). The detection thresholds of the implants were programmed to maximum sensitivity and both unipolar as well as bipolar electrode configurations were considered. The evaluation of possible interferences was derived from the internal event storages and pacing statistics recorded by the implants during exposure. Any "heart activity" recorded by the implants during exposure was interpreted as a potential interference, because the implant obviously misinterpreted the external interference signal as a physiological signal. Only cases without any recorded "heart activity" and with nominal pacing rates (as expected from the program parameter settings) of the implants were rated as "interference-free." Exposure to the whole body mat (peak magnetic induction up to 265 microT) did not show an influence on PMs and AICD in any case. The cushion applicator at the highest field intensity (peak magnetic induction up to 360 microT) led to atrial sensing defects in four PM models with unipolar electrode configuration. Under bipolar electrode configuration no disturbances occurred. The bar applicator led to sensing problems and consecutively reduced pacing rates in all tested PM models under unipolar electrode configuration and maximum field intensity (peak magnetic induction up to 980 microT). Bipolar electrode configuration resolved the problem. The investigated AICDs did not show malfunctions under any investigated condition. In conclusion, the examined PEMF therapy system did not interfere with the investigated implantable cardiac devices with bipolar electrode configuration. However, unipolar electrode configuration in pacemakers seems to be potentially hazardous during application of the examined PEMF therapy system. PMID:16607622

  6. The Solid-State Lithium Battery: A New Improved Chemical Power Source for Implantable Cardiac Pacemakers

    Microsoft Academic Search

    Wilson Greatbatch; John H. Lee; Walter Mathias; Margery Eldridge; James R. Moser; Alan A. Schneider

    1971-01-01

    A new solid-state battery, designed for implantable prosthetics is described. Single cell voltage is 2.8 V. The anode is metallic lithium. The cathode is a proprietary iodide. The electrolyte is a crystal, lithium iodide. Cell impedance at 37°C for a typical pacemaker battery is under 1000¿ at beginning of life (BOL) and 16 000 ¿ at end of life (EOL).

  7. Cardiac pacemaker lead extraction using conventional techniques:a single centre experience

    Microsoft Academic Search

    Gita Mathur; Rodney H. Stables; David Heaven; Zarah Stack; Amy Lovegrove; Ann Ingram; Richard Sutton

    2003-01-01

    Background: New methods of lead extraction using laser sheath devices are under evaluation but these techinques are not available in the majority of centres and have cost implications. Furthermore, in the absence of comparative randomised trials, registry experience with new devices must be judged against contemporary data using conventional methods. We report a single centre series of pacemaker lead extraction

  8. Evaluation of patients' quality of life aspects after cardiac pacemaker implantation

    PubMed Central

    de Barros, Rubens Tofano; de Carvalho, Sebastião Marcos Ribeiro; Silva, Marcos Augusto de Moraes; Borges, Juliana Bassalobre Carvalho

    2014-01-01

    Objective To evaluate patients' quality of life aspects after pacemaker implantation, relating it to gender, age, and implantation timespan. Methods A total of 107 clinically stable patients of both genders (49.5% women and 50.5% men) over 18 years old (average 69.3±12.6 years) and presenting an implantation timespan of three to 12 months (average 6.36±2.99 months) were evaluated. The evaluation included personal, clinical, and implant data as well as quality of life questionnaires (AQUAREL and SF-36). Statistical analysis was conducted using the t test and Pearson correlation, with a 5% significance level. Results The lowest SF-36 score referred to physical aspects, and the highest score referred to social aspects. In AQUAREL, the lowest score referred to dyspnea, and the highest referred to discomfort. There was a significant association between gender and quality of life in SF-36 (physical functioning and emotional aspects) and in AQUAREL (dyspnea). A negative correlation was observed between age and quality of life (functional capacity in SF-36, and discomfort in AQUAREL) in relation to implantation timespan, a correlation with vitality from SF-36. Conclusion Lower quality of life scores were found in physical aspects and dyspnea; and higher scores in social aspects and discomfort. Men presented higher quality of life scores related to physical functioning, emotional aspects and dyspnea. As age increases, quality of life worsens regarding functional capacity and discomfort; and the longer the pacemaker implantation timespan, the worse quality of life when it comes to vitality. Gender, age, and implantation timespan influence quality of life; thus, these variables must be considered in strategies for improving quality of life of patients with pacemakers. PMID:24896161

  9. Relation between QT interval and heart rate. New design of physiologically adaptive cardiac pacemaker

    Microsoft Academic Search

    A F Rickards; J Norman

    1981-01-01

    The relation between QT interval and heart rate has been studied in a group of patients undergoing physiological exercise, in a group undergoing atrial pacing without exercise, and in a group with complete heart block undergoing exercise at a fixed ventricular rate controlled by cardiac pacing. The expected shortening in QT interval during physiological exercise is only in part the

  10. Do we need MR conditional pacemakers?

    Microsoft Academic Search

    Roger Luechinger; Firat Duru

    2010-01-01

    Summary Magnetic resonance imaging (MRI) is a widely accepted tool for the diagnosis of a variety of disease states. However, due to safety concerns the presence of an im- planted cardiac pacemaker is considered to be a con- traindication to MRI in most medical centres. The increasing number of implanted pacemakers and the estimated over 50% probability that a pacemaker

  11. Electromagnetic interference from lasers and intense light sources in the treatment of patients with artificial pacemakers and other implantable cardiac devices.

    PubMed

    Lister, Tom; Grant, Lindsay; Lee, Siu-Man; Cole, Richard P; Jones, Anthony; Taylor, Timothy; Mayo, Angela; Wright, Philip A

    2015-07-01

    Measurements of the electric and magnetic field strengths surrounding six laser systems and one intense pulsed light system were carried out. The results were compared to exposure limits published by cardiac device manufacturers to assess the risk of electromagnetic interference to implantable cardiac devices such as pacemakers or implantable cardioverter defibrillators. The majority of lasers assessed in this study were found to produce electric and magnetic field strengths below the published exposure limits for cardiac devices. However, the low-frequency electric field and static magnetic field of both the CO2 laser and the ruby laser were found to exceed these limits. Ensuring that a small separation is maintained at all times between the laser unit and any patient with a pacemaker or implantable cardioverter defibrillator appears to be a sensible expedient in avoiding overexposure of an implantable cardiac device to electromagnetic interference. Due to the single-shot fast discharge nature of the intense pulsed light system, changes in electromagnetic field strength were too fast for some of the measuring equipment used in this study to register accurate readings during operation. PMID:24162308

  12. Can Smartphones Interfere with Pacemakers?

    MedlinePLUS

    ... As the European researchers explained, pacemakers might "misinterpret" electromagnetic interference (EMI) emanating from nearby smartphones as a ... implanted cardiac device. Participants were exposed to the electromagnetic field of three common smartphones: the Samsung Galaxy ...

  13. Effect of Surgical Atrial Fibrillation Ablation at the Time of Cardiac Surgery on Risk of Postoperative Pacemaker Implantation.

    PubMed

    El-Chami, Mikhael F; Binongo, José Nilo G; Levy, Mathew; Merchant, Faisal M; Halkos, Michael; Thourani, Vinod; Lattouf, Omar; Guyton, Robert; Puskas, John; Leon, Angel R

    2015-07-01

    The aim of this study was to retrospectively investigate whether performing surgical atrial fibrillation (AF) ablation in conjunction with cardiac surgery (CS) increases the risk for postoperative permanent pacemaker (PPM) requirement. The 30-day risk for PPM requirement was analyzed in consecutive patients who underwent CS from January 2007 to August 27, 2013. Patients were divided into 3 groups: (1) those who underwent AF ablation concomitant with CS (AF ABL), (2) patients with any history of AF who underwent surgery who did not undergo ablation (AF NO ABL), and (3) those with no histories of AF who underwent surgery (NO AF). Logistic regression analysis was performed adjusting for age, gender, and surgery type. Of 13,453 CS patients, 353 (3%) were in the AF ABL group, 1,701 (12%) in the AF NO ABL group, and 11,399 (85%) in the NO AF group. A total of 7,651 patients (57%) underwent coronary artery bypass grafting, 4,384 (33%) underwent valve surgery, and 1,418 (10%) underwent coronary artery bypass grafting and valve surgery. The overall PPM risk was 1.6% (212 of 13,453); risk was 5.7% (20 of 353) in the AF ABL group, 3.1% (53 of 1,701) in the AF NO ABL group, and 1.2% (139 of 11,399) in the NO AF group. The unadjusted and adjusted odds of PPM were higher in the AF ABL and AF NO ABL groups than in the NO AF group (adjusted odds ratio [OR] 2.7, 95% confidence interval [CI] 1.7 to 4.4, and adjusted OR 1.7, 95% CI 1.2 to 2.4, respectively). The unadjusted OR comparing the AF ABL group and the AF NO ABL group was significant (unadjusted OR 1.9, 95% CI 1.9 to 3.2); however, the OR adjusted for surgery type, age, and gender showed a trend toward significance (adjusted OR 1.6, 95% CI 0.9 to 2.7). In conclusion, in this large cohort of patients who underwent CS, surgical AF ablation appeared to carry an increased risk for postoperative PPM implantation. PMID:25933731

  14. 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

  15. Preliminary clinical experience with a new radioisotope-powered cardiac pacemaker.

    PubMed

    Smyth, N P; Magovern, G J; Cushing, W J; Keshishian, J M; Kelly, L C; Dixon, M

    1976-02-01

    A small light-weight nuclear-powered pacer has been developed. The pulse generator weight 61 Gm. and occupies a volume of 33 sq. cm. It is a standard R-wave inhibited (VVI) demand pulse generator. The unit has met all United States and foreign atomic energy commission safety specifications including mechanical shock, industrial fire, accidental crush, cremation, impact, and corrosion. Its calculated life is in excess of 20 years. The unit has been shown to be insensitive to electromagnetic interference (EMI) over a wide range of commonly encountered sources of interference. An extensive dog testing program has been carried out and is continuing. The United States Atomic Energy Commission (AEC) has issued a license to conduct clinical trials. These began in October, 1974, and a total of 30 units of 30 units have been implanted so far. An equal number of chemical battery-powered pulse generators has been implanted in a control series of 30 patients. Preliminary results have been gratifying. PMID:1107679

  16. The behavior of dual-chamber pacemakers exposed to a conducted low-frequency disruptive signal.

    PubMed

    Babouri, A; Hedjiedj, A; Guendouz, L; Andretzko, J P

    2006-08-01

    This paper presents a study of the behavior of dual-chamber cardiac pacemakers submitted to low-frequency conducted disruptions. The disruptive signal is sinusoidal, operating at 50 Hz, 60 Hz, 10 kHz and 25 kHz. The behavior of the pacemakers is described by statistical data obtained with a telemetry system and by visualization of the pacemaker signal during the application of the interfering signal. The pacemakers were tested in two configurations. The first one consists of direct application of the interfering signal between the pacemaker terminals. In the second, these attempts are completed by in vitro tests using an electromagnetic model which allow us to take into account the interface which constitutes the human body. The pacemaker under test is inserted into a gelatine phantom mimicking the electrical conductivity of tissues. This study allowed us to define the pacemaker detection thresholds for the two test configurations. For the in vitro approach, which constitutes a complementary approach to a realistic implantation situation, oversensing is noticed for 10 kHz and 25 kHz interfering signal frequencies. Detection thresholds vary from a few tens to a few hundreds of mV, depending on the interfering signal frequency, the device and its programmed detection sensitivities. PMID:16772671

  17. Legal Aspects of Cardiac Rehabilitation Exercise Programs.

    ERIC Educational Resources Information Center

    Herbert, William; Herbert, David L.

    1988-01-01

    A medical model is used to examine liability issues related to cardiac rehabilitation programs. Obtaining effective informed consent from patients, standardizing policies and procedures, and exercise prescription and monitoring are among the proposed elements of a risk management model for developing safe and legally defensible programs. (IAH)

  18. 42 CFR 410.49 - Cardiac rehabilitation program and intensive cardiac rehabilitation program: Conditions of coverage.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...iv) Systolic blood pressure. (v) Diastolic blood pressure. (vi) The need for cholesterol, blood pressure, and diabetes medications. (3) A list of approved intensive cardiac rehabilitation programs, identified through the national...

  19. “The attack of the 52 cm lead”: An unusual case of late cardiac perforation by a passive-fixation permanent pacemaker lead

    Microsoft Academic Search

    Marcellus Francis Ramirez; Chi Keong Ching; Kah Leng Ho; Wee Siong Teo

    2007-01-01

    We report a case of right ventricular perforation by a passive-tined permanent pacemaker lead detected 1 month after implantation. The pacemaker lead was seen to perforate through the myocardium and pericardium and moving freely in the mediastinum with no evidence of pericardial effusion. Extraction was uneventful.

  20. Optogenetic Control of Cardiac Function

    Microsoft Academic Search

    Aristides B. Arrenberg; Didier Y. R. Stainier; Herwig Baier; Jan Huisken

    2010-01-01

    The cardiac pacemaker controls the rhythmicity of heart contractions and can be substituted by a battery-operated device as a last resort. We created a genetically encoded, optically controlled pacemaker by expressing halorhodopsin and channelrhodopsin in zebrafish cardiomyocytes. Using patterned illumination in a selective plane illumination microscope, we located the pacemaker and simulated tachycardia, bradycardia, atrioventricular blocks, and cardiac arrest. The

  1. Cardiac fiber unfolding by semidefinite programming.

    PubMed

    Li, Hongying; Robini, Marc C; Yang, Feng; Magnin, Isabelle; Zhu, Yuemin

    2015-02-01

    Diffusion-tensor imaging allows noninvasive assessment of the myocardial fiber architecture, which is fundamental in understanding the mechanics of the heart. In this context, tractography techniques are often used for representing and visualizing cardiac fibers, but their output is only qualitative. We introduce here a new framework toward a more quantitative description of the cardiac fiber architecture from tractography results. The proposed approach consists in taking three-dimensional (3-D) fiber tracts as inputs, and then unfolding these fibers in the Euclidean plane under local isometry constraints using semidefinite programming. The solution of the unfolding problem takes the form of a Gram matrix which defines the two-dimensional (2-D) embedding of the fibers and whose spectrum provides quantitative information on their organization. Experiments on synthetic and real data show that unfolding makes it easier to observe and to study the cardiac fiber architecture. Our conclusion is that 2-D embedding of cardiac fibers is a promising approach to supplement 3-D rendering for understanding the functioning of the heart. PMID:25291787

  2. Evaluation of Effects of the Microwave Oven (915 and 2450 MHz) and Radar (2810 and 3050 MHz) Electromagnetic Radiation on Noncompetitive Cardiac Pacemakers

    Microsoft Academic Search

    Charles H. Bonney; Gary E. Ford

    1973-01-01

    Using pacemakers implanted in canines with surgically induced atrioventricular blocks, the effects of the microwave-oven frequencies (915 and 2450 MHz) and two radar frequencies (2810 and 3050 MHz) were evaluated. Quantitative evaluation of these fields with respect to complete inhibition of pacemakers can be made. A narrow zone of inhibition during some exposures-a ``window'' effect-not previously described is reported. The

  3. Energy-conserving programming of VVI pacemakers: a telemetry-supported, long-term, follow-up study.

    PubMed

    Klein, H H; Knake, W

    1990-06-01

    Thirty patients with VVI pacemakers (Quantum 253-09, 253-19, Intermedics Inc., Freeport, TX) were observed for a mean of 65 months. Within 12 months after implantation, optimized output programming was performed in 29 patients. This included a decrease in pulse amplitude (22 patients), pulse width (4 patients), and/or pacing rate (11 patients). After 65 months postimplantation, telemetered battery voltage and battery impedance were compared with the predicted values expected when the pulse generator constantly stimulates at nominal program conditions (heart rate 72.3 beats/min, pulse amplitude 5.4 V, pulse width 0.61 ms). Instead of an expected cell voltage of 2.6 V and a cell impedance of 10 k omega mean telemetered values amounted to 2.78 V and 1.4 k omega, respectively. These data correspond to a battery age of 12-15 months at nominal program conditions. This long-term follow-up study suggests that adequate programming will extend battery longevity and thus pulse generator survival in many patients. PMID:2344702

  4. CHEMICAL PACEMAKERS

    PubMed Central

    Hadidian, Zareh; Hoagland, Hudson

    1939-01-01

    1. Iron spicules found in the brains of general paretic patients are formed from endogenous brain iron normally present in another form. This supports our earlier view that the µ value of 16,000 obtained in advanced paretics for alpha brain wave frequencies as a measure of cortical respiration comes about from the slowing of an iron catalyzed link in cortical respiration such as would result from the reduction of available cytochrome and its oxidase, thus making this step a chemical pacemaker. 2. To test the basic theory of chemical pacemakers, a study was made of the succinate-fumarate enzyme system containing succino-dehydrogenase and cytochrome-cytochrome oxidase acting sequentially. 3. The µ value for the unpoisoned system is 11,200 ± 200 calories. 4. According to theory, the addition of a critical amount of cyanide known to be a specific poison of the cytochrome-cytochrome oxidase system (and not of the dehydrogenase) should shift the µ cleanly to 16,000 calories, and it does. 5. According to theory, selenite, a specific poison for the dehydrogenase, should stop all respiration without shifting the µ. This also is found to be the case. 6. The theory also predicts that if the µ is shifted from 11,000 ± to 16,000 ± by cyanide, the subsequent addition of a critical amount of selenite should shift the µ back again to 11,000 ± calories, and this is found to occur. 7. It is concluded that approximately 11,000 calories is the energy of activation of the succino-dehydrogenase-catalyzed step and 16,000 calories is that for the cytochrome-cytochrome oxidase-catalyzed step. These two values are encountered more frequently than any others in physiological systems. It is to be recalled that a shift of µ for alpha brain wave frequencies from 11,000 to 16,000 calories occurs in the course of advancing syphilitic brain infection and is accompanied by a change in form of brain iron. PMID:19873142

  5. Pacemaker insertion

    PubMed Central

    Kotsakou, Maria; Kioumis, Ioannis; Lazaridis, George; Pitsiou, Georgia; Lampaki, Sofia; Papaiwannou, Antonis; Karavergou, Anastasia; Tsakiridis, Kosmas; Katsikogiannis, Nikolaos; Karapantzos, Ilias; Karapantzou, Chrysanthi; Baka, Sofia; Mpoukovinas, Ioannis; Karavasilis, Vasilis; Rapti, Aggeliki; Trakada, Georgia; Zissimopoulos, Athanasios; Zarogoulidis, Konstantinos

    2015-01-01

    A pacemaker (PM) (or artificial PM, so as not to be confused with the heart’s natural PM) is a medical device that uses electrical impulses, delivered by electrodes contracting the heart muscles, to regulate the beating of the heart. The primary purpose of this device is to maintain an adequate heart rate, either because the heart’s natural PM is not fast enough, or there is a block in the heart’s electrical conduction system. Modern PMs are externally programmable and allow the cardiologist to select the optimum pacing modes for individual patients. Some combine a PM and defibrillator in a single implantable device. PMs can be temporary or permanent. Temporary PMs are used to treat short-term heart problems, such as a slow heartbeat that’s caused by a heart attack, heart surgery, or an overdose of medicine. Permanent PMs are used to control long-term heart rhythm problems. A PM can relieve some arrhythmia symptoms, such as fatigue and fainting. A PM also can help a person who has abnormal HRs resume a more active lifestyle. In the current mini review we will focus on the insertion of a PM and the possible pneumothorax that can be caused. PMID:25815303

  6. Cardiac Bioelectricity and Arrhythmias

    NSDL National Science Digital Library

    Flavio Fenton (Cornell University; )

    2006-09-22

    Deep inside a human heart, its pacemaker sends out bursts of electrical signals that keep the heart pumping rhythmically, supplying life-giving oxygen to the body. When these electrical waves become disorganized, the heart starts beating irregularly or arrhythmically. Flavio Fenton and Elizabeth Cherry of Cornell University made this interactive program to provide education on arrhythmias. It presents detailed information on cardiac anatomy, normal cardiac electrophysiology, and different kinds of arrhythmias using a combination of words, pictures, and interactive, computer simulations and animations.

  7. CHEMICAL PACEMAKERS

    PubMed Central

    Hadidian, Zareh; Hoagland, Hudson

    1941-01-01

    1. In a previous paper it was found that 11,200 calories is obtained for the energy of activation in the oxidation of succinate to fumarate in the presence of crude beef heart extract when succino-dehydrogenase was made the limiting factor. 16,000 calories was obtained with this preparation when cytochrome-cytochrome oxidase was made the limiting factor. In the present paper activation energies of the components of this enzyme system are further studied. 2. Oxidation of p-phenylenediamine catalyzed by the extract and known not to involve the dehydrogenase component yields Arrhenius equation plots indicating a pacemaker reaction with a µ of 9,500 calories. 3. An activation energy of 17,500 calories is obtained for the oxidation of succinate to fumarate in the presence of the beef heart extract partially poisoned by pyrophosphate. Evidence is presented that this value corresponds to a link in the respiratory chain other than that of succino-dehydrogenase or cytochrome c-cytochrome oxidase. 4. Addition of a suitable amount of cresyl blue to a beef heart extract reaction mixture, completely inhibited by cyanide, restores the oxidation of succinate to normal in the presence of pure oxygen. In this system, in which the dye is substituted for the oxidase, when the enzyme extract (dehydrogenase) is made the limiting factor, a µ of 18,500 calories is obtained; when cresyl blue is made the limiting factor, the µ value is 22,000 calories. 5. Results of these experiments indicate that energies of activation are associated not with the enzyme as such, but with the particular reaction steps involving them as catalysts. PMID:19873220

  8. Localization of (-)-[125I]cyanopindolol binding in guinea-pig heart: characteristics of non-beta-adrenoceptor related binding in cardiac pacemaker and conducting regions.

    PubMed

    Molenaar, P; Kompa, A R; Roberts, S J; Pak, H S; Summers, R J

    1992-02-17

    Receptor autoradiography was used in guinea-pig heart to locate binding sites for the beta-adrenoceptor ligand (-)[125I]cyanopindolol (CYP) resistant to blockade by the beta-adrenoceptor antagonist (-)-propranolol (1 microM). Highly localized binding was observed to regions closely associated with the sinoatrial node, atrioventricular node and bundle of His but was not observed on myocardial, pacemaker, conducting cells or adipose tissue. Free [125I] also bound to identical sites. Binding was enhanced in the presence of ascorbic acid but was completely inhibited by (-)-isoprenaline (100 microM), serotonin (5-HT) (10 microM) and phentolamine (10 microM). PMID:1321964

  9. A patient with dizziness, tachycardia and a DDDR pacemaker

    PubMed Central

    Balt, J.C.; Dekker, P.; de Voogt, W.G.

    2006-01-01

    An 84-year-old female patient presented to the coronary care unit with dizziness. A DDD-R minute ventilation sensor pacemaker had been implanted eight years previously. The ECG showed an atrial and ventricular paced rhythm of 140 beats/min. After disconnecting the patient from the cardiac monitor the pacemaker rate dropped gradually to 90 beats/min. The cardiac rhythm monitoring system applies low-amplitude electrical pulses in order to measure respiration rate by transthoracic impedance (TTI) measurement. The minute ventilation pacemaker sensor is driven by the same TTI measurement for rate response. Inappropriate interference between these two systems caused a sensor-driven high pacemaker rate. The dizziness was not related to the sensor-driven high rate. ImagesFigure 1Figure 2 PMID:25696553

  10. MRI-conditional pacemakers: current perspectives

    PubMed Central

    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. PMID:24851058

  11. Perceptions of cardiac rehabilitation patients, specialists and rehabilitation programs regarding cardiac rehabilitation wait times

    PubMed Central

    2012-01-01

    Background In 2006, the Canadian Cardiovascular Society (CCS) Access to Care Working Group recommended a 30-day wait time benchmark for cardiac rehabilitation (CR). The objectives of the current study were to: (1) describe cardiac patient perceptions of actual and ideal CR wait times, (2) describe and compare cardiac specialist and CR program perceptions of wait times, as well as whether the recommendations are appropriate and feasible, and (3) investigate actual wait times and factors that CR programs perceive to affect these wait times. Methods Postal and online surveys to assess perceptions of CR wait times were administered to CR enrollees at intake into 1 of 8 programs, all CCS member cardiac specialists treating patients indicated for CR, and all CR programs listed in Canadian directories. Actual wait times were ascertained from the Canadian Cardiac Rehabilitation Registry. The design was cross-sectional. Responses were described and compared. Results Responses were received from 163 CR enrollees, 71 cardiac specialists (9.3% response rate), and 92 CR programs (61.7% response rate). Patients reported that their wait time from hospital discharge to CR initiation was 65.6?±?88.4?days (median, 42?days), while their ideal median wait time was 28?days. Most patients (91.5%) considered their wait to be acceptable, but ideal wait times varied significantly by the type of cardiac indication for CR. There were significant differences between specialist and program perceptions of the appropriate number of days to wait by most indications, with CR programs perceiving shorter waits as appropriate (p?programs reported that feasible wait times were significantly longer than what was appropriate for all indications (p?program initiation was 64?days (mean, 80.0?±?62.8?days), with no difference in wait by indication. Conclusions Wait times following access to cardiac rehabilitation are prolonged compared with consensus recommendations, and yet are generally acceptable to most patients. Wait times following percutaneous coronary intervention in particular may need to be shortened. Future research is required to provide an evidence base for wait time benchmarks. PMID:22897912

  12. Cardiac Fiber Unfolding by Semidefinite Programming

    E-print Network

    Robini, Marc - Pôle de Mathématiques, Institut National des Sciences Appliquées de Lyon

    of the unfolding problem takes the form of a Gram matrix which defines the two-dimensional embedding of the fibers. INTRODUCTION THe human myocardium is composed of branched my- ocytes which are approximately 25 µm in diameter. However, cardiac myocytes form elon- gated structures with a preferential local orientation, which

  13. Heart pacemaker - discharge

    MedlinePLUS

    ... blender, computers and fax machines, hair dryer, stove, CD player, remote controls, and microwave. You should keep ... Swerdlow CD, Hayes DL, Zipes DP. Pacemakers and implantable cardioverter-defibrillators. In: Mann DL, Zipes DP, Libby P, et ...

  14. Pacemaker lead endocarditis

    PubMed Central

    Scheffer, M.; van der Linden, E.; van Mechelen, R.

    2003-01-01

    We present a patient with a pacemaker lead endocarditis who showed no signs of pocket infection but with high fever and signs of infection in the routine laboratory tests. A diagnosis of pacemaker lead endocarditis must be considered in all patients with fever and infection parameters who have a pacemaker inserted, not only in the first weeks after implantation but also late after implantation, as long as no other cause of infection has been found. Transthoracal echocardiography alone is not sensitive enough to establish the correct diagnosis. Transoesophageal echocardiography (TEE) is mandatory to demonstrate the presence or absence of a vegetation on a pacemaker lead. ImagesFigure 1Figure 2Figure 3Figure 4 PMID:25696204

  15. Magnetic Resonance Imaging Conditional Pacemakers: Rationale, Development and Future Directions

    PubMed Central

    Cronin, Edmond M; Wilkoff, Bruce L

    2012-01-01

    Pacemakers and other cardiac implantable electronic devices (CIEDs) have long been considered an absolute contraindication to magnetic resonance imaging (MRI), a crucial and growing imaging modality. In the last 20 years, protocols have been developed to allow MR scanning of CIED patients with a low complication rate. However, this practice has remained limited to a relatively small number of centers, and many pacemaker patients continue to be denied access to clinically indicated imaging. The introduction of MRI conditional pacemakers has provided a widely applicable and satisfactory solution to this problem. Here, the interactions of pacemakers with the MR environment, the results of MR scanning in patients with conventional CIEDs, the development and clinical experience with MRI conditional devices, and future directions are reviewed. PMID:23071382

  16. [Cardiac manifestations of mitochondrial diseases].

    PubMed

    Ritzenthaler, Thomas; Luis, David; Hullin, Thomas; Fayssoil, Abdallah

    2015-05-01

    Mitochondrial diseases are multi-system disorders in relation with mitochondrial DNA and/or nuclear DNA abnormalities. Clinical pictures are heterogeneous, involving endocrine, cardiac, neurologic or sensory systems. Cardiac involvements are morphological and electrical disturbances. Prognosis is worsened in case of cardiac impairment. Treatments are related to the type of cardiac dysfunction including medication or pacemaker implantation. PMID:25890847

  17. Cardiac Rehabilitation

    MedlinePLUS

    ... from the NHLBI on Twitter. What Is Cardiac Rehabilitation? Cardiac rehabilitation (rehab) is a medically supervised program ... be designed to meet your needs. The Cardiac Rehabilitation Team Cardiac rehab involves a long-term commitment ...

  18. Delayed right-ventricular perforation by pacemaker lead; a rare complication in a 12-year-old girl.

    PubMed

    Aykan, Hayrettin Hakan; Ak?n, Alper; Ertu?rul, ?lker; Karagöz, Tevfik

    2015-03-01

    Developments in the diagnosis and treatment of congenital heart diseases have led to an increase in the need for intracardiac pacemaker and implantable cardioverter defibrillator (ICD) implantation. Various complications related to these interventions can be seen in the short term (pneumothorax, pericardial effusion, cardiac perforation, etc…) and in the long term (infection, subclavian vein thrombosis, sensing and pacing problems, battery erosion and cardiac perforation). In this report, we present a rare case of cardiac perforation occurring 2 years after pacemaker implantation. PMID:25782125

  19. Reuse Of Pacemakers In Ghana And Nigeria: Medical, Legal, Cultural And Ethical Perspectives.

    PubMed

    Ochasi, Aloysius; Clark, Peter

    2014-04-11

    According to the World Health Organization (WHO) cardiovascular disease (CVD) is the leading cause of death globally. Over 80% of CVD deaths take place in low- and middle-income countries (LMICs). It is estimated that 1 million to 2 million people worldwide die each year due to lack of access to an implantable cardiac defibrillator (ICD) or a pacemaker. Despite the medical, legal, cultural and ethical controversies surrounding the pacemaker reutilization, studies done so far on the reuse of postmortem pacemakers show it to be safe and effective with an infection rate of 1.97% and device malfunction rate of 0.68%. Pacemaker reutilization can be effectively and safely done and does not pose significant additional risk to the recipient. Heart patients with reused pacemakers have an improved quality of life compared to those without pacemakers. The thesis of this paper is that pacemaker reutilization is a life-saving initiative in LMICs of Nigeria and Ghana. It is cost effective; consistent with the principles of beneficence, nonmaleficence, and justice with a commitment to stewardship of resources and the Common Good. Used pacemakers with adequate battery life can be properly sterilized for use by patients in LMICs who cannot afford the cost of a new pacemaker. PMID:24720369

  20. The experiences of patients undertaking a 'virtual' cardiac rehabilitation program.

    PubMed

    Banner, Davina; Lear, Scott; Kandola, Daman; Singer, Joel; Horvat, Dan; Bates, Joanna; Ignaszewski, Andrew

    2015-01-01

    Cardiac rehabilitation programs (CRP) are medically supervised, multidisciplinary programs that provide secondary prevention aimed at addressing risk factors and improving lifestyle behaviours for patients following an acute cardiac event. CRPs have been demonstrated to be a cost-effective and evidence-based mechanism to improve patient outcomes, but despite the known benefits of these programs, uptake remains poor. Poor attendance has been linked to many factors, but geographical accessibility is a key concern, since many CRPs are limited to hospitals in urban areas. The widespread availability of the Internet has made it possible to provide virtual health services to populations that may have previously been hard to access. This paper examines the qualitative findings from a 16-month mixed methods randomized controlled trial examining the impact of a virtual CRP (vCRP). The vCRP was revealed to be an accessible, appropriate, convenient and effective way to deliver cardiac rehabilitation services, with patients experiencing both clinical improvements and a high level of satisfaction. To understand the experience of patients undertaking the vCRP, semi-structured interviews were undertaken with a purposive sample of 22 participants. An analysis of the qualitative interviews revealed that the vCRP improved participants' access to healthcare professionals, supported them to make healthy choices, and enhanced feelings of accountability due to greater surveillance. Barriers to participation, such as computer literacy, and general perceptions of a vCRP were also examined. Further investigation into the use and long-term effectiveness of virtual programs across a broader range of healthcare settings is warranted, particularly in those with multiple chronic diseases and those located in rural and remote communities. PMID:25980699

  1. Radiation safety program for the cardiac catheterization laboratory.

    PubMed

    Chambers, Charles E; Fetterly, Kenneth A; Holzer, Ralf; Lin, Pei-Jan Paul; Blankenship, James C; Balter, Stephen; Laskey, Warren K

    2011-03-01

    The Society of Cardiovascular Angiography and Interventions present a practical approach to assist cardiac catheterization laboratories in establishing a radiation safety program. The importance of this program is emphasized by the appropriate concerns for the increasing use of ionizing radiation in medical imaging, and its potential adverse effects. An overview of the assessment of radiation dose is provided with a review of basic terminology for dose management. The components of a radiation safety program include essential personnel, radiation monitoring, protective shielding, imaging equipment, and training/education. A procedure based review of radiation dose management is described including pre-procedure, procedure and post-procedure best practice recommendations. Specific radiation safety considerations are discussed including women and fluoroscopic procedures as well as patients with congenital and structural heart disease. PMID:21254324

  2. [Right heart failure resulting from pacemaker lead-induced tricuspid valve regurgitation].

    PubMed

    Schroeter, T; Strotdrees, E; Doll, N; Mohr, F W

    2011-06-01

    Pacemaker lead-induced tricuspid valve regurgitation is a severe and often underdiagnosed complication due to the widely variable time interval between implantation and the development of severe tricuspid valve insufficiency with ensuing right heart failure. Complete explantation of inactive pacemaker leads is necessary to avoid permanent damage to right heart structures. If performed in a timely fashion, regression of tricuspid insufficiency can be achieved without additional cardiac procedures. PMID:21547560

  3. In vitro investigation of eddy current effect on pacemaker operation generated by low frequency magnetic field.

    PubMed

    Babouri, A; Hedjeidj, A

    2007-01-01

    This paper presents in vitro investigation of the eddy current induction effects to the cardiac pacemaker exposed to low frequency magnetic fields. The method used in this study is based to the interaction by inductive coupling through the loop formed by the pacemaker and its leads and the surrounding medium. This interaction results in an induced electromotive force between the terminals of the pacemaker which can potentially disturb the operation of this last. In this article we present experimental results, analytical calculations and numerical simulations using the finite element method. PMID:18003302

  4. [Interstitial pacemaker cells].

    PubMed

    Niziaeva, N V; Shchegolev, A I; Mare?, M V; Sukhikh, G T

    2014-01-01

    This article is devoted to interstitial Cajal cells (syn. telocytes, interstitial pacemaker cells, IPC). First those cells were discovered by C.R Cajal in the muscle coat of the gut in 1893. Nowadays they have revealed in all parts of digestive systems (from esophagus to rectum), urinary and biliary tracts, prostate, liver, the walls of arteries and lymphatics, as well Fallopian tube, myometrium, mammary glands. Characteristic ultrastructural features are elongated spindle shape, length from 40 to 100 ?m, the thickness of 0.2-0.5 ?m, the presence of 2-5 processes. Length of them rangingfrom tens to hundreds of micrometers, some of them have secondary and tertiary branching, forming a three-dimensional network. IPC having spontaneous electrical (pacemaker) activity are cause to contraction of smooth muscle cells. Depending on the location of IPC have different morphological and ultrastructural characteristics. Characteristic immunohistochemical markers are CD117, CD34, S100, vimentin. IPC replay to acetylcholine, norepinephrine, estrogen, progesterone, and nitric oxide by influence ofcorresponding receptors. IPC have specific gap junctions with lymphocytes, basophiles, eosinophils, neutrophils, mast cells and dendritic cells. Grave pathology of those cells are forming gastrointestinal stromal tumors. PMID:25563000

  5. Review Article Gene Therapy in Cardiac Arrhythmias

    Microsoft Academic Search

    Johnson Francis

    Gene therapy has progressed from a dream to a bedside reality in quite a few human diseases. From its first application in adenosine deaminase deficiency, through the years, its application has evolved to vascular angiogenesis and cardiac arrhythmias. Gene based biological pacemakers using viral vectors or mesenchymal cells tested in animal models hold much promise. Induction of pacemaker activity within

  6. Pacemakers and Implantable Defibrillators - Multiple Languages: MedlinePlus

    MedlinePLUS

    ... Institute Pacemaker (Arabic) ??????? Bilingual PDF Health Information Translations Chinese - Simplified (????) Pacemaker ????? - ???? (Chinese - Simplified) Bilingual PDF Health Information Translations Chinese - Traditional (????) Pacemaker ????? - ???? (Chinese - Traditional) ...

  7. Ventricular pacing on the prognosis of patients with pacemaker implantation.

    PubMed

    Zheng, Liuying; Du, Xinping

    2014-06-01

    Excessive right ventricular apex pacing has significant adverse effects on the cardiac function and hence, it is necessary to clinically optimize pacing parameters and advocate suitable physiological pacing to safeguard the cardiac function after pacemaker implant. Minimizing ventricular pacing is an atrioventricular node priority function, to encourage ventricular self conduction and to reduce unnecessary right ventricular pacing. Minimized ventricular pacing reduces ventricular pacing by encouraging self atrioventricular conduction function and extending the AV interval. This study is a prospective cohort study to evaluate the changes of cardiac function in patients and serum amino-terminal natriuretic peptide (NT-proBNP) before and after pacing, and the risk of atrial fibrillation with different CUM% VP. The study has shown that the cardiac function will deteriorate with an increase in pacing rate. PMID:24242189

  8. 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. PMID:22673497

  9. Interference of apex locator, pulp tester and diathermy on pacemaker function

    PubMed Central

    Sriman, Narayanan; Prabhakar, V.; Bhuvaneswaran, J.S.; Subha, N.

    2015-01-01

    Aim: The purpose of this study was to evaluate the effects of three electronic apex locators (EAL), electric pulp tester (EPT) and diathermy on pacemaker function in vitro. Materials and Methods: Three EALs: Root ZX (J. Morita Co., Tustin, CA, U.S.A.), Propex (Dentsply), Mini Apex locator (SybronEndo, Anaheim, CA, USA), EPT (Parkell pulp vitality tester Farmingdale, NY, USA) and Diathermy (Neomed 250 B) were tested for any interference with one pacemaker (A medtronic kappa KVDD901-serial number: PLE734632S). Directly connecting the pacemaker lead with the EAL/EPT/diathermy operating on a flat bench top, the telemetry wand was held directly over the pacemaker to monitor the pacing pattern for a period of 30 s. Pacemaker activity was continuously recorded on the telemetric programmer and electro gram (EGM) readings examined for pacer inhibition, noise reversion or inappropriate pacemaker pulses. Results: All the three apex locators showed no pacing interference or background noise during its function or at rest. The EGM readings of EPT showed varying levels of background noise in between pacing however, this did not affect the normal pacing pattern and the pacing interval remained constant. EGM readings of diathermy showed an increase in the pacing interval (irregular pacing pattern) followed by complete inhibition of the pacing system. Conclusion: The tested EALs do not interfere with cardiac pacemaker function. The tested EPT showed varying levels of background noise but does not interfere with cardiac pacemaker function. Use of Diathermy interfered with the normal pacing, leading to complete inhibition of the pacing system. PMID:25657520

  10. Developing a Culturally Based Cardiac Rehabilitation Program: The HELA Study

    PubMed Central

    Look, Mele A; Kaholokula, Joseph Keawe‘aimoku; Carvahlo, Amy; Seto, Todd B.; de Silva, Mapuana

    2012-01-01

    Background Heart disease disproportionately affects Native Hawaiians and other Pacific people. In response, researchers proposed and communities endorsed, developing a cardiac rehabilitation (CR) program based on the hula, a Native Hawaiian dance form. The utilization of cultural practices in health interventions can improve outcomes and increase enrollment and retention, but requires sensitivity and understanding. Objective This paper provides the conceptual framework and methods used for integration of multiple communities’ perspectives to inform the design of a hula-based CR intervention. Methods Specific strategies and processes were established to ensure the equity of scientific—clinical and patient—cultural knowledge and perspectives. Multiple methods were used and a flow diagram defined steps for the intervention development. Results Patient and cultural consultations provided information about the multidimensional benefits of hula and its use in a CR intervention. Clinical and scientific consultations provided specific guidelines for exercise prescription and patient monitoring. Integrating findings from all consultations identified important direction and requirements. Conclusions Community-based participatory research (CBPR) principles guided a complex collaboration of multiple communities; although time consuming, inclusive consultations provided valuable information and relationships. PMID:22643794

  11. Pacemaking Kisspeptin Neurons

    PubMed Central

    Kelly, Martin J.; Zhang, Chunguang; Qiu, Jian; Rønnekleiv, Oline K.

    2013-01-01

    Kisspeptin (Kiss1) neurons are vital for reproduction. GnRH neurons express the kisspeptin receptor, GPR 54, and kisspeptins potently stimulate the release of GnRH by depolarising and inducing sustained action potential firing in GnRH neurons. As such Kiss1 neurons may be the pre-synaptic pacemaker neurons in the hypothalamic circuitry that controls reproduction. There are at least two different populations of Kiss1 neurons: one in the rostral periventricular area (RP3V) that is stimulated by oestrogens and the other in the arcuate nucleus that is inhibited by oestrogens. How each of these Kiss1 neuronal populations participate in the regulation of the reproductive cycle is currently under intense investigation. Based on electrophysiological studies in the guinea pig and mouse, Kiss1 neurons in general are capable of generating burst firing behavior. Essentially all Kiss1 neurons, which have been studied thus far in the arcuate nucleus, express the ion channels necessary for burst firing, which include hyperpolarization-activated, cyclic nucleotide gated cation (HCN) channels and the T-type calcium (Cav3.1) channels. Under voltage clamp conditions, these channels produce distinct currents that under current clamp conditions can generate burst firing behavior. The future challenge is to identify other key channels and synaptic inputs involved in the regulation of the firing properties of Kiss1 neurons and the physiological regulation of the expression of these channels and receptors by oestrogens and other hormones. The ultimate goal is to understand how Kiss1 neurons control the different phases of GnRH neurosecretion and hence reproduction. PMID:23884368

  12. [Pacemaker-Twiddler's Syndrome (author's transl)].

    PubMed

    Kolb, P; Kauffmann, P

    1978-11-24

    A case of Pacemaker-Twiddler's Syndrome is presented. Rotation of a permanent pacemaker can result in a capstan effect, and the lead is drawn out of the right ventricle. Fixing thouroughly the pacemaker and the lead should be an useful prophylactic measure. PMID:723748

  13. Ethical Dilemmas and End-of-Life Choices for Patients with Implantable Cardiac Devices: Decisions Regarding Discontinuation of Therapy

    Microsoft Academic Search

    Blair P. Grubb; Beverly Karabin

    Opinion statement  It is our belief that a well-designed cardiac device management program should include end-of-life patient and family planning,\\u000a addressing potential decisions regarding withdrawal of pacemaker and\\/or implantable cardioverter defibrillator therapy. Guided\\u000a by the basic ethical and legal principles outlined in the article, it is the responsibility of the electrophysiologist and\\u000a other involved health care providers to introduce this topic

  14. Placement of a temporary pacemaker electrode through a persistent left superior vena cava

    Microsoft Academic Search

    T. A. Cron; P. T. Buser; S. Osswald

    1998-01-01

    Perioperative temporary pacing was needed in a patient with congenital skeletal malformations and a cardiac conduction disturbance\\u000a with incomplete trifascicular block. We report the successful placement of the pacemaker electrode through a persistent left\\u000a superior vena cava (SVC).

  15. Hierarchy of the heart rhythmogenesis levels is a factor in increasing the reliability of cardiac activity

    Microsoft Academic Search

    Vladimir M Pokrovskii

    2006-01-01

    Summary Along with the existence of an intracardiac pacemaker a generator of cardiac rhythm exists in the central nervous system - in the efferent structures of the cardiovascular center of the medullar oblongata. Neural signals originating there in the form of bursts of impulses conduct to the heart along the vagus nerves and after interaction with cardiac pacemaker structures causegeneration

  16. Forward Programming of Cardiac Stem Cells by Homogeneous Transduction with MYOCD plus TBX5

    PubMed Central

    Belian, Elisa; Noseda, Michela; Abreu Paiva, Marta S.; Leja, Thomas; Sampson, Robert; Schneider, Michael D.

    2015-01-01

    Adult cardiac stem cells (CSCs) express many endogenous cardiogenic transcription factors including members of the Gata, Hand, Mef2, and T-box family. Unlike its DNA-binding targets, Myocardin (Myocd)—a co-activator not only for serum response factor, but also for Gata4 and Tbx5—is not expressed in CSCs. We hypothesised that its absence was a limiting factor for reprogramming. Here, we sought to investigate the susceptibility of adult mouse Sca1+ side population CSCs to reprogramming by supplementing the triad of GATA4, MEF2C, and TBX5 (GMT), and more specifically by testing the effect of the missing co-activator, Myocd. Exogenous factors were expressed via doxycycline-inducible lentiviral vectors in various combinations. High throughput quantitative RT-PCR was used to test expression of 29 cardiac lineage markers two weeks post-induction. GMT induced more than half the analysed cardiac transcripts. However, no protein was detected for the induced sarcomeric genes Actc1, Myh6, and Myl2. Adding MYOCD to GMT affected only slightly the breadth and level of gene induction, but, importantly, triggered expression of all three proteins examined (?-cardiac actin, atrial natriuretic peptide, sarcomeric myosin heavy chains). MYOCD + TBX was the most effective pairwise combination in this system. In clonal derivatives homogenously expressing MYOCD + TBX at high levels, 93% of cardiac transcripts were up-regulated and all five proteins tested were visualized. In summary: (1) GMT induced cardiac genes in CSCs, but not cardiac proteins under the conditions used. (2) Complementing GMT with MYOCD induced cardiac protein expression, indicating a more complete cardiac differentiation program. (3) Homogeneous transduction with MYOCD + TBX5 facilitated the identification of differentiating cells and the validation of this combinatorial reprogramming strategy. Together, these results highlight the pivotal importance of MYOCD in driving CSCs toward a cardiac muscle fate. PMID:26047103

  17. The cardiac implantable electronic device power source: evolution and revolution.

    PubMed

    Mond, Harry G; Freitag, Gary

    2014-12-01

    Although the first power source for an implantable pacemaker was a rechargeable nickel-cadmium battery, it was rapidly replaced by an unreliable short-life zinc-mercury cell. This sustained the small pacemaker industry until the early 1970s, when the lithium-iodine cell became the dominant power source for low voltage, microampere current, single- and dual-chamber pacemakers. By the early 2000s, a number of significant advances were occurring with pacemaker technology which necessitated that the power source should now provide milliampere current for data logging, telemetric communication, and programming, as well as powering more complicated pacing devices such as biventricular pacemakers, treatment or prevention of atrial tachyarrhythmias, and the integration of innovative physiologic sensors. Because the current delivery of the lithium-iodine battery was inadequate for these functions, other lithium anode chemistries that can provide medium power were introduced. These include lithium-carbon monofluoride, lithium-manganese dioxide, and lithium-silver vanadium oxide/carbon mono-fluoride hybrids. In the early 1980s, the first implantable defibrillators for high voltage therapy used a lithium-vanadium pentoxide battery. With the introduction of the implantable cardioverter defibrillator, the reliable lithium-silver vanadium oxide became the power source. More recently, because of the demands of biventricular pacing, data logging, and telemetry, lithium-manganese dioxide and the hybrid lithium-silver vanadium oxide/carbon mono-fluoride laminate have also been used. Today all cardiac implantable electronic devices are powered by lithium anode batteries. PMID:25387600

  18. 21 CFR 870.3730 - Pacemaker service tools.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 false Pacemaker service tools. 870.3730 Section 870.3730 Food...Devices § 870.3730 Pacemaker service tools. (a) Identification. Pacemaker service tools are devices such as screwdrivers and...

  19. 21 CFR 870.3730 - Pacemaker service tools.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 false Pacemaker service tools. 870.3730 Section 870.3730 Food...Devices § 870.3730 Pacemaker service tools. (a) Identification. Pacemaker service tools are devices such as screwdrivers and...

  20. 21 CFR 870.3730 - Pacemaker service tools.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 false Pacemaker service tools. 870.3730 Section 870.3730 Food...Devices § 870.3730 Pacemaker service tools. (a) Identification. Pacemaker service tools are devices such as screwdrivers and...

  1. 21 CFR 870.3730 - Pacemaker service tools.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 false Pacemaker service tools. 870.3730 Section 870.3730 Food...Devices § 870.3730 Pacemaker service tools. (a) Identification. Pacemaker service tools are devices such as screwdrivers and...

  2. 21 CFR 870.3730 - Pacemaker service tools.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 false Pacemaker service tools. 870.3730 Section 870.3730 Food...Devices § 870.3730 Pacemaker service tools. (a) Identification. Pacemaker service tools are devices such as screwdrivers and...

  3. Gene Therapy to Create Biological Pacemakers

    Microsoft Academic Search

    Gerard J. J. Boink; Jurgen Seppen; Jacques M. T. Bakker; Hanno L. Tan

    Old age and a variety of cardiovascular disorders may disrupt normal sinus node function. Currently, this is successfully\\u000a treated with electronic pacemakers, which, however, leave room for improvement. During the past decade, different strategies\\u000a to initiate pacemaker function by gene therapy were developed. In the search for a biological pacemaker, various approaches\\u000a were explored, including ?\\u000a 2-adrenergic receptor overexpression, down

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

    SciTech Connect

    Ch'ng, Julie; Chan, William; Lee, Paul; Joshi, Subodh; Grigg, Leanne E.; Ajani, Andrew E

    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 illustrates the risk of endocarditis in the population with congenital heart disease and an intracardiac device.

  5. Utility of a dedicated pediatric cardiac anticoagulation program: the Boston Children's Hospital experience.

    PubMed

    Murray, Jenna M; Hellinger, Amy; Dionne, Roger; Brown, Loren; Galvin, Rosemary; Griggs, Suzanne; Mittler, Karen; Harney, Kathy; Manzi, Shannon; VanderPluym, Christina; Baker, Annette; O'Brien, Patricia; O'Connell, Cheryl; Almond, Christopher S

    2015-04-01

    Congenital heart disease is the leading cause of stroke in children. Warfarin therapy can be difficult to manage safely in this population because of its narrow therapeutic index, multiple drug and dietary interactions, small patient size, high-risk cardiac indications, and lack of data to support anticoagulation recommendations. We sought to describe our institution's effort to develop a dedicated cardiac anticoagulation service to address the special needs of this population and to review the literature. In 2009, in response to Joint Commission National Patient Safety Goals for Anticoagulation, Boston Children's Hospital created a dedicated pediatric Cardiac Anticoagulation Monitoring Program (CAMP). The primary purpose was to provide centralized management of outpatient anticoagulation to cardiac patients, to serve as a disease-specific resource to families and providers, and to devise strategies to evolve clinical care with rapidly emerging trends in anticoagulation care. Over 5 years the CAMP Service, staffed by a primary pediatric cardiology attending, a full-time nurse practitioner, and administrative assistant with dedicated support from pharmacy and nutrition, has enrolled over 240 patients ranging in age from 5 months to 55 years. The most common indications include a prosthetic valve (34 %), Fontan prophylaxis (20 %), atrial arrhythmias (11 %), cardiomyopathy (10 %), Kawasaki disease (7 %), and a ventricular assist device (2 %). A patient-centered multi-disciplinary cardiac anticoagulation clinic was created in 2012. Overall program international normalized ratio (INR) time in therapeutic range (TTR) is favorable at 67 % (81 % with a 0.2 margin) and has improved steadily over 5 years. Pediatric-specific guidelines for VKOR1 and CYP2C9 pharmacogenomics testing, procedural bridging with enoxaparin, novel anticoagulant use, and quality metrics have been developed. Program satisfaction is rated highly among families and providers. A dedicated pediatric cardiac anticoagulation program offers a safe and effective strategy to standardize anticoagulation care for pediatric cardiology patients, is associated with high patient and provider satisfaction, and is capable of evolving care strategies with emerging trends in anticoagulation. PMID:25573076

  6. Environmental Effects on Cardiac Pacing Systems

    Microsoft Academic Search

    Louise Cohan; Fred M. Kusumoto; Nora F. Goldschlager

    Early artificial pacemakers delivered asynchronous pulses at a fixed rate regardless of the intrinsic activity of the heart.\\u000a As pacemaker technology improved, devices were developed that not only delivered pacing stimuli but also sensed intrinsic\\u000a cardiac electrical activity. However, the circuitry used to detect small amplitude (1–20 mV) intracardiac electrical signals\\u000a generated by the atrium and ventricle can also detect

  7. A DYNAMIC PROGRAMMING SOLUTION TO TRACKING AND ELASTICALLY MATCHING LEFT VENTRICULAR WALLS IN CARDIAC CINE MRI

    E-print Network

    Tsaftaris, Sotirios

    A DYNAMIC PROGRAMMING SOLUTION TO TRACKING AND ELASTICALLY MATCHING LEFT VENTRICULAR WALLS match the con- tours of the epicardial walls of the left ventricle (LV) in cardiac phase-resolved 2-D among different sets of cine MRI images. Future extensions include comparisons with contours hand

  8. Evaluating the Effectiveness of an Interactive Multimedia Computer-based Patient Education Program in Cardiac Rehabilitation.

    ERIC Educational Resources Information Center

    Jenny, Ng Yuen Yee; Fai, Tam Sing

    2001-01-01

    A study compared 48 cardiac patients who used an interactive multimedia computer-assisted patient education program and 48 taught by tutorial. The computer-assisted instructional method resulted in significantly better knowledge about exercise and self-management of chronic diseases. (Contains 29 references.) (JOW)

  9. [Diagnostic application of external electrical impulses in form of an overdrive for the influence of an implanted QRS inhibited demand pacemaker system (author's transl)].

    PubMed

    Rost, P; Pippig, L

    1976-03-01

    The possibility of influencing an implanted demand pacemaker system by means of an external electrical impulse has already been described by several authors. In this paper further clinical applications of this method are discussed in relationship to patients who have a pacemaker of the QRS inhibited type. Electrodes are applied externally over the regions of the pacemaker generator and the catheter tip. Electrical impulses are then given at a higher frequency than those of the implanted pacemaker, thus enabling the impulses of the internal pacemaker to be inhibited, and consequently the spontaneous action of the heart to be observed. Further possible clinical applications with the aid of examples are discussed: the identification of persistent arrhythmias, digitalis intoxication, fresh cardiac ischaemias, as well as evidence of the need for temporary stimulation during generator change. PMID:1263990

  10. Successful Treatment of Occipital Neuralgia with Implantable Peripheral Nerve Stimulation in a Pacemaker-Dependent Patient

    PubMed Central

    Chaiban, Gassan; Tolba, Reda; Eissa, Hazem; Lirette, Lesley Smallwood; Almualim, Mohammed; Malaty, Adham; Atallah, Joseph

    2014-01-01

    Background Peripheral nerve stimulation has been used to treat patients with occipital nerve–related chronic headaches who have been unsuccessful with less invasive therapeutic approaches. Patients with pacemaker-dependent cardiac conduction abnormalities require unique consideration prior to the implantation of peripheral nerve stimulators because the placement of the devices may lead to failure of the systems secondary to electromagnetic interference or crosstalk between the devices. Case Report An 86-year-old female who suffered from chronic right-sided cervicogenic headaches and neck pain had received only temporary relief from previous treatments. Additional comorbidities included longstanding pacemaker-dependent atrioventricular node conduction disease. Because the extent to which nerve stimulators electrically interact with pacemakers is unclear, we tunneled the leads to the lumbar region of the back and placed the generator on the contralateral side to the pacemaker to minimize the chance that the 2 devices would interfere. The patient has remained pain free for 1 year since implantation. Conclusion Although no current published trials evaluate the degree of interference between medical devices, case reports increasingly suggest that simultaneous implantation of a spinal cord stimulator and pacemaker is safe as long as precautions are taken and the devices are checked periodically, particularly when the devices are adjusted. PMID:24688344

  11. [State-of-the-art and prospects of high-tech medical aid to patients with cardiac arrhythmia based at military medical facilities].

    PubMed

    Steklov, V I

    2014-01-01

    Analysis of provision of high-tech medical aid to patients with cardiac arrhythmia based at military medical facilities showed that the available means and workforce are sufficient for the purpose. In order to facilitate access to high-tech medical aid it is necessary to equip arrhythmologic departments with up-to-date-instruments and set up cabinets of electrocardiostimulation in regional (naval) hospitals for implantation of temporary and permanent pacemakers. A program is pending for education (primary specialization) and advanced training of specialists in clinical cardiac electrophysiology, interventional and surgical arrhythmology. PMID:25269209

  12. Pacemakers charging using body energy.

    PubMed

    Bhatia, Dinesh; Bairagi, Sweeti; Goel, Sanat; Jangra, Manoj

    2010-01-01

    Life-saving medical implants like pacemakers and defibrillators face a big drawback that their batteries eventually run out and patients require frequent surgery to have these batteries replaced. With the advent of technology, alternatives can be provided for such surgeries. To power these devices, body energy harvesting techniques may be employed. Some of the power sources are patient's heartbeat, blood flow inside the vessels, movement of the body parts, and the body temperature (heat). Different types of sensors are employed, such as for sensing the energy from the heartbeat the piezoelectric and semiconducting coupled nanowires are used that convert the mechanical energy into electricity. Similarly, for sensing the blood flow energy, nanogenerators driven by ultrasonic waves are used that have the ability to directly convert the hydraulic energy in human body to electrical energy. Another consideration is to use body heat employing biothermal battery to generate electricity using multiple arrays of thermoelectric generators built into an implantable chip. These generators exploit the well-known thermocouple effect. For the biothermal device to work, it needs a 2°C temperature difference across it. But there are many parts of the body where a temperature difference of 5°C exists - typically in the few millimeters just below the skin, where it is planned to place this device. This study focuses on using body heat as an alternative energy source to recharge pacemaker batteries and other medical devices and prevent the possibility of life-risk during repeated surgery. PMID:21814432

  13. Pacemakers charging using body energy

    PubMed Central

    Bhatia, Dinesh; Bairagi, Sweeti; Goel, Sanat; Jangra, Manoj

    2010-01-01

    Life-saving medical implants like pacemakers and defibrillators face a big drawback that their batteries eventually run out and patients require frequent surgery to have these batteries replaced. With the advent of technology, alternatives can be provided for such surgeries. To power these devices, body energy harvesting techniques may be employed. Some of the power sources are patient's heartbeat, blood flow inside the vessels, movement of the body parts, and the body temperature (heat). Different types of sensors are employed, such as for sensing the energy from the heartbeat the piezoelectric and semiconducting coupled nanowires are used that convert the mechanical energy into electricity. Similarly, for sensing the blood flow energy, nanogenerators driven by ultrasonic waves are used that have the ability to directly convert the hydraulic energy in human body to electrical energy. Another consideration is to use body heat employing biothermal battery to generate electricity using multiple arrays of thermoelectric generators built into an implantable chip. These generators exploit the well-known thermocouple effect. For the biothermal device to work, it needs a 2°C temperature difference across it. But there are many parts of the body where a temperature difference of 5°C exists – typically in the few millimeters just below the skin, where it is planned to place this device. This study focuses on using body heat as an alternative energy source to recharge pacemaker batteries and other medical devices and prevent the possibility of life-risk during repeated surgery. PMID:21814432

  14. Atrio-ventricular block requiring pacemaker in patients with late onset Pompe disease.

    PubMed

    Sacconi, Sabrina; Wahbi, Karim; Theodore, Guillaume; Garcia, Jérémy; Salviati, Leonardo; Bouhour, Françoise; Vial, Christophe; Duboc, Denis; Laforêt, Pascal; Desnuelle, Claude

    2014-07-01

    Enzyme replacement therapy consistently improves cardiac function in infantile and juvenile onset patients with Pompe disease and cardiomyopathy, but is apparently not effective in preventing rhythm disorders, an emerging cardiac phenotype in long term survivors. In patients with late onset Pompe disease cardiomyopathy is an exceptional finding while heart rhythm disorders seem to be more frequent. We retrospectively identified, among a cohort of 131 French late onset Pompe disease patients, four patients with severe atrio-ventricular blocks requiring pacemaker implantation. These patients had no other risk factors for cardiovascular diseases or cardiomyopathy. In one patient the atrioventricular block was discovered while still asymptomatic. Cardiac conduction defects are relatively rare in late onset Pompe disease and may occur even in absence of cardiac symptoms or EKG abnormalities. However because of the possible life-threatening complications associated with these conduction defects, cardiac follow-up in patients with late onset Pompe disease should include periodical Holter-EKG monitoring. PMID:24844452

  15. Evaluation of bluetooth low power for physiological monitoring in a home based cardiac rehabilitation program.

    PubMed

    Martin, Timothy; Ding, Hang; D'Souza, Matthew; Karunanithi, Mohan

    2012-01-01

    Cardiovascular disease (CVD) is the leading cause of mortality in Australia, and places large burdens on the healthcare system. To assist patients with CVDs in recovering from cardiac events and mediating cardiac risk factors, a home based cardiac rehabilitation program, known as the Care Assessment Platform (CAP), was developed. In the CAP program, patients are required to manually enter health information into their mobile phones on a daily basis. The manual operation is often subject to human errors and is inconvenient for some elderly patients. To improve this, an automated wireless solution has been desired. The objectives of this paper are to investigate the feasibility of implementing the newly released Bluetooth 4.0 (BT4.0) for the CAP program, and practically evaluate BT4.0 communications between a developed mobile application and some emulated healthcare devices. The study demonstrated that BT4.0 addresses usability, interoperability and security for healthcare applications, reduces the power consumption in wireless communication, and improves the flexibility of interface for software development. This evaluation study provides an essential mobile BT4.0 framework to incorporate a large range of healthcare devices for clinical assessment and intervention in the CAP program, and hence it is useful for similar development and research work of other mobile healthcare solutions. PMID:22797030

  16. Alterations of field potentials in isotropic cardiomyocyte cell layers induced by multiple endogenous pacemakers under normal and hypothermal conditions.

    PubMed

    Kienast, R; Stöger, M; Handler, M; Hanser, F; Baumgartner, C

    2014-10-01

    The use of autonomous contracting randomly grown cardiomyocyte monolayers cultivated on microelectrode arrays (MEAs) represents an accepted experimental setting for preclinical experimental research in the field of cardiac electrophysiology. A dominant pacemaker forces a monolayer to adhere to a regular and synchronized contraction. Randomly distributed multiple pacemakers interfere with this dominant center, resulting in more or less frequent changes of propagation direction. This study aims to characterize the impact of changing propagation directions at single electrodes of the MEA on the four intrinsic parameters of registered field potentials (FPs) FPrise, FPMIN, FPpre, and FPdur and conduction velocity (CV) under normal and hypothermal conditions. Primary cultures of chicken cardiomyocytes (n = 18) were plated directly onto MEAs and FPs were recorded in a temperature range between 37 and 29°C. The number and spatiotemporal distribution of biological and artificial pacemakers of each cell layer inside and outside of the MEA registration area were evaluated using an algorithm developed in-house. In almost every second myocardial cell layer, interfering autonomous pacemakers were detected at stable temperatures, showing random spatial distributions with similar beating rates. Additionally, a temperature-dependent change of the dominant pacemaker center was observed in n = 16 experiments. A significant spread-direction-dependent variation of CV, FPrise, FPMIN, and FPpre up to 14% could be measured between different endogenous pacemakers. In conclusion, based on our results, disregarding the spatial origin of excitation may lead to misinterpretations and erroneous conclusions of FP parameters in the verification of research hypotheses in cellular electrocardiology. PMID:25085965

  17. Automatic detection of cardiac contours on MR images using fuzzy logic and dynamic programming.

    PubMed

    Lalande, A; Legrand, L; Walker, P M; Jaulent, M C; Guy, F; Cottin, Y; Brunotte, F

    1997-01-01

    This paper deals with the use of fuzzy logic and dynamic programming in the detection of cardiac contours in MR Images. The definition of two parameters for each pixel allows the construction of the fuzzy set of the cardiac contour points. The first parameter takes into account the grey level, and the second the presence of an edge. A corresponding fuzzy matrix is derived from the initial image. Finally, a dynamic programming with graph searching is performed on this fuzzy matrix. The method has been tested on several MR images and the results of the contouring were validated by an expert in the domain. This preliminary work clearly demonstrates the interest of this method, although a formal evaluation has to be done. PMID:9357671

  18. SU-D-18C-06: Initial Experience with Implementing MRI Safety Guidelines for Patients with Pacemakers - Medical Physicist Perspective

    SciTech Connect

    James, J; Place, V; Panda, A [Mayo Clinic, Scottsdale, AZ (United States); Edmonson, H [Mayo Clinic College of Medicine, Rochester, MN (United States); Felmlee, J [Mayo Clinic, Rochester, MN (United States); Pooley, R [Mayo Clinic, Jacksonville, FL (United States)

    2014-06-01

    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, 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.

  19. Upregulation of Programmed Death-1 and Its Ligand in Cardiac Injury Models: Interaction with GADD153

    PubMed Central

    Baban, Babak; Liu, Jun Yao; Qin, Xu; Weintraub, Neal L.; Mozaffari, Mahmood S.

    2015-01-01

    Purpose Programmed Death-1 (PD-1) and its ligand, PD-L1, are regulators of immune/ inflammatory mechanisms. We explored the potential involvement of PD-1/PD-L1 pathway in the inflammatory response and tissue damage in cardiac injury models. Experimental Design Ischemic-reperfused and cryoinjured hearts were processed for flow cytometry and immunohistochemical studies for determination of cardiac PD-1 and PD-L1 in the context of assessment of the growth arrest- and DNA damage-inducible protein 153 (GADD153) which regulates both inflammation and cell death. Further, we explored the potential ability of injured cardiac cells to influence proliferation of T lymphocytes. Results The isolated ischemic-reperfused hearts displayed marked increases in expression of PD-1 and PD-L1 in cardiomyocytes; however, immunofluorescent studies indicate that PD-1 and PD-L1 are not primarily co-expressed on the same cardiomyocytes. Upregulation of PD-1/PD-L1 was associated with a) marked increases in GADD153 and interleukin (IL)-17 but a mild increase in IL-10 and b) disruption of mitochondrial membrane potential (?m) as well as apoptotic and necrotic cell death. Importantly, while isotype matching treatment did not affect the aforementioned changes, treatment with the PD-L1 blocking antibody reversed those effects in association with marked cardioprotection. Further, ischemic-reperfused cardiac cells reduced proliferation of T lymphocytes, an effect partially reversed by PD-L1 antibody. Subsequent studies using the cryoinjury model of myocardial infarction revealed significant increases in PD-1, PD-L1, GADD153 and IL-17 positive cells in association with significant apoptosis/necrosis. Conclusions The data suggest that upregulation of PD-1/PD-L1 pathway in cardiac injury models mediates tissue damage likely through a paracrine mechanism. Importantly, inhibition of T cell proliferation by ischemic-reperfused cardiac cells is consistent with the negative immunoregulatory role of PD-1/PD-L1 pathway, likely reflecting an endogenous cardiac mechanism to curtail the deleterious impact of infiltrating immune cells to the damaged myocardium. The balance of these countervailing effects determines the extent of cardiac injury. PMID:25902191

  20. MGH West Cardiac Wellness Program Optimizing Health and Enhancing Resiliency

    E-print Network

    Mootha, Vamsi K.

    -healthy diet, assist in weight management and improve glucose and cholesterol levels · A comprehensive stress management program with an emphasis on learning relaxation techniques to help you reduce stress and increase and Mind Your Heart: A Mind Body Approach to Stress Management, Exercise and Nutrition for Heart Health

  1. Use of the automatic external defibrillator-pacemaker by ambulance personnel: the Stockport experience.

    PubMed Central

    Gray, A J; Redmond, A D; Martin, M A

    1987-01-01

    In an attempt to reduce the number of people who die from a cardiac arrest in the Stockport area ambulances were equipped with automatic external defibrillator-pacemakers, and ambulance personnel were trained in their use. Over an 18 month period ambulance personnel attended 113 patients in cardiac arrest with these devices. One patient subsequently survived, and three patients survived for up to three days. The reasons for these poor initial results include the failure of bystanders to provide cardiopulmonary resuscitation, a delay in calling for the ambulance, and too few defibrillators being available. PMID:3107727

  2. How Will a Pacemaker Affect My Lifestyle?

    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 ...

  3. Cardiac sarcoidosis: a comprehensive review

    PubMed Central

    Sekhri, Vishal; Sanal, Shireen; DeLorenzo, Lawrence J.; Aronow, Wilbert S.; Maguire, George P.

    2011-01-01

    Sarcoidosis is a multisystem granulomatous disease of unknown etiology characterized by noncaseating granulomas in involved organs. Organs involved with sarcoidosis include lymph nodes, skin, lung, central nervous system, and eye. Only 40-50% of patients with cardiac sarcoidosis diagnosed at autopsy have the diagnosis made during their lifetime. Cardiac sarcoidosis can manifest itself as complete heart block, ventricular arrhythmias, congestive heart failure, pericardial effusion, pulmonary hypertension, and ventricular aneurysms. Diagnostic tests such as the electrocardiogram, two-dimensional echocardiography, cardiac magnetic resonance imaging, positron emission tomography scan, radionuclide scan, and endomyocardial biopsy can be helpful in the early detection of cardiac sarcoidosis. Considering the increased risk of sudden death, cardiac sarcoidosis is an indication for early treatment with corticosteroids or other immunosuppressive agents. Other treatments include placement of a pacemaker or implantable defibrillator to prevent sudden death. In refractory cases, cardiac transplantation should be considered. PMID:22291785

  4. Management of recurrent pacemaker-related bacteraemia with small colony variant Staphylococcus aureus in a haemodialysis patient

    PubMed Central

    Nielsen, Xiaohui Chen; Nielsen, Finn Thomsen; Kurtzhals, Jørgen A L; Moser, Claus; Boye, Kit; Christensen, Jens Jørgen; Johansen, Ulla Rydal; Westh, Henrik

    2009-01-01

    A patient with chronic haemodialysis with a cardiac pacemaker was admitted for five episodes of bacteraemia with Staphylococcus during an 8-month period. The species identification was complicated since the morphological characters and biochemical reactions were unusual and differing. Molecular biological identification and typing methods revealed that the pathogens for all the episodes were the same strain of Staphylococcus aureus that had small colony variant characteristics. Continuous suppressive antibiotic treatment initiated after the last infection episode has been able to keep the patient free of bacteraemia relapse during the past 24 months without removing the pacemaker. PMID:21857872

  5. Deactivation of Pacemakers and Implantable Cardioverter-Defibrillators

    PubMed Central

    Kramer, Daniel B.; Mitchell, Susan L.; Brock, Dan W.

    2013-01-01

    Cardiac implantable electrical devices (CIEDs), including pacemakers (PMs) and implantable cardioverter-defibrillators (ICDs), are the most effective treatment for life-threatening arrhythmias. Patients or their surrogates may request device deactivation to avoid prolongation of the dying process or in other settings, such as after device-related complications or with changes in their health care goals. Despite published guidelines outlining theoretical and practical aspects of this common clinical scenario, significant uncertainty remains for both patients and health care providers regarding the ethical and legal status of CIED deactivation. This review outlines the ethical and legal principles supporting CIED deactivation at patients’ request, centered upon patient autonomy and authority over their own medical treatment. The empirical literature describing stakeholder views and experiences surrounding CIED deactivation is described, along with lessons for future research and practice guidance surrounding the care of patients with CIEDs. PMID:23217433

  6. Alternative view on the mechanism of cardiac rhythmogenesis

    Microsoft Academic Search

    Vladimir M. Pokrovskii

    2003-01-01

    Background: This article advances an hypothesis that there is duplication of the heart rhythmogenesis system.Methods and Results: The following article reviews available data and advances an hypothesis to suggest new ideas about the mechanisms of cardiac rhythm generation. The hypothesis is that along with the existence of an intracardiac pacemaker, the generator of cardiac rhythm exists in the central nervous

  7. The pacemaker activity generating the intrinsic myogenic contraction of the dorsal vessel of Tenebrio molitor (Coleoptera).

    PubMed

    Markou, T; Theophilidis, G

    2000-11-01

    Combined intracellular and extracellular recordings from various parts of the isolated dorsal vessel of Tenebrio molitor revealed some of the following electrophysiological properties of the heart and the aorta. (i) The wave of depolarization causing forward pulsation of the dorsal vessel was always transmitted from posterior to anterior, with a conduction velocity of 0.014 m s(-1) in the heart and 0.001 m s(-1) in the aorta when the heart rate was 60 beats min(-1). (ii) There was no pacemaker activity in the aorta. (iii) The duration of the compound action potential in the aortic muscle depended on the duration of the pacemaker action potential generated in the heart. (iv) Isolated parts of the heart continued to contract rhythmically for hours, indicating powerful pacemaker activity in individual cardiac segments. (v) There was a direct relationship between action potential duration and the length of the preceding diastolic interval. (vi) The rhythmic wave of depolarization was dependent on the influx of Ca(2+). (vii) The recovery of the electrical properties of myocardial cells that had been disrupted by sectioning was rapid. (viii) In hearts sectioned into two halves, the rhythmic pacemaker action potentials recorded simultaneously from the two isolated halves eventually drifted out of phase, but they had the same intrinsic frequency. In the light of these data, we discuss two alternative models for the generation of spontaneous rhythmic pumping movements of the heart and aorta. PMID:11044385

  8. The G-protein–gated K+ channel, IKACh, is required for regulation of pacemaker activity and recovery of resting heart rate after sympathetic stimulation

    PubMed Central

    Mesirca, Pietro; Marger, Laurine; Toyoda, Futoshi; Rizzetto, Riccardo; Audoubert, Matthieu; Dubel, Stefan; Torrente, Angelo G.; DiFrancesco, Mattia L.; Muller, Jana Christina; Leoni, Anne-Laure; Couette, Brigitte; Nargeot, Joël; Clapham, David E.; Wickman, Kevin

    2013-01-01

    Parasympathetic regulation of sinoatrial node (SAN) pacemaker activity modulates multiple ion channels to temper heart rate. The functional role of the G-protein–activated K+ current (IKACh) in the control of SAN pacemaking and heart rate is not completely understood. We have investigated the functional consequences of loss of IKACh in cholinergic regulation of pacemaker activity of SAN cells and in heart rate control under physiological situations mimicking the fight or flight response. We used knockout mice with loss of function of the Girk4 (Kir3.4) gene (Girk4?/? mice), which codes for an integral subunit of the cardiac IKACh channel. SAN pacemaker cells from Girk4?/? mice completely lacked IKACh. Loss of IKACh strongly reduced cholinergic regulation of pacemaker activity of SAN cells and isolated intact hearts. Telemetric recordings of electrocardiograms of freely moving mice showed that heart rate measured over a 24-h recording period was moderately increased (10%) in Girk4?/? animals. Although the relative extent of heart rate regulation of Girk4?/? mice was similar to that of wild-type animals, recovery of resting heart rate after stress, physical exercise, or pharmacological ?-adrenergic stimulation of SAN pacemaking was significantly delayed in Girk4?/? animals. We conclude that IKACh plays a critical role in the kinetics of heart rate recovery to resting levels after sympathetic stimulation or after direct ?-adrenergic stimulation of pacemaker activity. Our study thus uncovers a novel role for IKACh in SAN physiology and heart rate regulation. PMID:23858001

  9. The G-protein-gated K+ channel, IKACh, is required for regulation of pacemaker activity and recovery of resting heart rate after sympathetic stimulation.

    PubMed

    Mesirca, Pietro; Marger, Laurine; Toyoda, Futoshi; Rizzetto, Riccardo; Audoubert, Matthieu; Dubel, Stefan; Torrente, Angelo G; Difrancesco, Mattia L; Muller, Jana Christina; Leoni, Anne-Laure; Couette, Brigitte; Nargeot, Joël; Clapham, David E; Wickman, Kevin; Mangoni, Matteo E

    2013-08-01

    Parasympathetic regulation of sinoatrial node (SAN) pacemaker activity modulates multiple ion channels to temper heart rate. The functional role of the G-protein-activated K(+) current (IKACh) in the control of SAN pacemaking and heart rate is not completely understood. We have investigated the functional consequences of loss of IKACh in cholinergic regulation of pacemaker activity of SAN cells and in heart rate control under physiological situations mimicking the fight or flight response. We used knockout mice with loss of function of the Girk4 (Kir3.4) gene (Girk4(-/-) mice), which codes for an integral subunit of the cardiac IKACh channel. SAN pacemaker cells from Girk4(-/-) mice completely lacked IKACh. Loss of IKACh strongly reduced cholinergic regulation of pacemaker activity of SAN cells and isolated intact hearts. Telemetric recordings of electrocardiograms of freely moving mice showed that heart rate measured over a 24-h recording period was moderately increased (10%) in Girk4(-/-) animals. Although the relative extent of heart rate regulation of Girk4(-/-) mice was similar to that of wild-type animals, recovery of resting heart rate after stress, physical exercise, or pharmacological ?-adrenergic stimulation of SAN pacemaking was significantly delayed in Girk4(-/-) animals. We conclude that IKACh plays a critical role in the kinetics of heart rate recovery to resting levels after sympathetic stimulation or after direct ?-adrenergic stimulation of pacemaker activity. Our study thus uncovers a novel role for IKACh in SAN physiology and heart rate regulation. PMID:23858001

  10. 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. PMID:10089864

  11. Implementation of Ultraportable Echocardiography in an Adolescent Sudden Cardiac Arrest Screening Program

    PubMed Central

    Vanhecke, Thomas E; Weber, James E; Ebinger, Matthew; Bonzheim, Kimberly; Tilli, Frank; Rao, Sunilkumar; Osman, Abdulfatah; Silver, Marc; Fliegner, Karsten; Almany, Steve; Haines, David

    2014-01-01

    BACKGROUND Over a 12-month period, adolescent heart-screening programs were performed for identifying at-risk adolescents for sudden cardiac death (SCD) in our community. Novel to our study, all adolescents received an abbreviated, ultraportable echocardiography (UPE). In this report, we describe the use of UPE in this screening program. METHODS AND RESULTS Four hundred thirty-two adolescents underwent cardiac screening with medical history questionnaire, physical examination, 12-lead electrocardiogram (ECG), and an abbreviated transthoracic echocardiographic examination. There were 11 abnormalities identified with uncertain/varying clinical risk significance. In this population, 75 adolescents had a murmur or high ECG voltage, of which only three had subsequent structural abnormalities on echocardiography that may pose risk. Conversely, UPE discovered four adolescents who had a cardiovascular structural abnormality that was not signaled by the 12-lead ECG, medical history questionnaire, and/or physical examination. CONCLUSIONS The utilization of ultraportable, handheld echocardiography is feasible in large-scale adolescent cardiovascular screening programs. UPE appears to be useful for finding additional structural abnormalities and for risk-stratifying abnormalities of uncertain potential of adolescents’ sudden death. PMID:25249762

  12. World's Tiniest Pacemaker Seems Safe, Effective in Trial

    MedlinePLUS

    ... nlm.nih.gov/medlineplus/news/fullstory_152575.html World's Tiniest Pacemaker Seems Safe, Effective in Trial Device ... 2015 FRIDAY, May 15, 2015 (HealthDay News) -- The world's smallest pacemaker is safe and effective in patients ...

  13. Pacemakers handshake synchronization mechanism of mammalian respiratory rhythmogenesis

    Microsoft Academic Search

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

    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

  14. [New pacemaker functions: which ones represent real progress and which are only gadgets?].

    PubMed

    Dodinot, B

    2000-07-01

    Modern pacemakers, and particularly dual chamber models, include a broad array of therapeutic and diagnostic features. Some are designed to increase safety, whereas others are either designed to avoid unnecessary pacing, reduce the current drain and increase the pacemaker longevity, or to improve the hemodynamics. Diagnostic features are more elaborate, more or less automatic, and easier to extract from the pacemaker memory. Some of these new algorithms represent a real advantage, while others appear to be more like gadgets than real advances. Several new algorithms should be improved in order to avoid possibly dangerous side effects. Most of these new features are of little value in the absence of postoperative programming by a well trained physician. PMID:12555487

  15. Echo-driven V-V optimization determines clinical improvement in non responders to cardiac resynchronization treatment.

    PubMed

    Naqvi, Tasneem Z; Rafique, Asim M; Peter, C Thomas

    2006-01-01

    Echocardiography plays an integral role in the detection of mechanical dyssynchrony in patients with congestive heart failure and in predicting beneficial response to cardiac resynchronization treatment. In patients who derive sup-optimal benefit from biventricular pacing, optimization of atrioventricular delay post cardiac resynchronization treatment has been shown to improve cardiac output. Some recent reports suggest that sequential ventricular pacing may further improve cardiac output. The mechanism whereby sequential ventricular pacing improves cardiac output is likely improved inter and possibly intraventricular synchrony, however these speculations have not been confirmed. In this report we describe the beneficial effect of sequential V-V pacing on inter and intraventricular synchrony, cardiac output and mitral regurgitation severity as the mechanisms whereby sequential biventricular pacing improves cardiac output and functional class in 8 patients who had derived no benefit or had deteriorated after CRT. Online tissue Doppler imaging including tissue velocity imaging, tissue synchronization imaging and strain and strain rate imaging were used in addition to conventional pulsed wave and color Doppler during sequential biventricular pacemaker programming. PMID:17049099

  16. Automated Verification of Quantitative Properties of Cardiac Pacemaker Software

    E-print Network

    Oxford, University of

    Identifier 10.4230/OASIcs.MCPS.2014.137 1 Introduction Today's implantable medical devices are increasingly their safe operation and to avoid costly device recalls. The natural models for medical devices Commons License CC-BY Medical Cyber Physical Systems ­ Medical Device Interoperability, Safety

  17. A DIFFERENTIAL MODEL OF CONTROLLED CARDIAC PACEMAKER CELL

    E-print Network

    Paris-Sud XI, Université de

    that includes Ca2+ binding by myoplasmic proteins, and the intracellular concentrations of free Calcium, Sodium of the main ionic currents (inward sodium, L-type calcium and outward potassium), Na+ /Ca2+ exchangers and Na characteristics of isolated ion channels can now be measured. They are based on the ionic current model

  18. Delayed pacemaker erosion due to electrode seal defects.

    PubMed

    Cohn, J D; Santhanam, R; Rosenbloom, M A; Thorson, R F

    1979-11-01

    Over a 7-year period, follow-up data were available on 163 patients who underwent 209 pacemaker-related operations for initial insertion or revision of previously implanted units. During the follow-up period, 16 pacemaker generator units were remoaved from 16 pacemaker generator units were removed from 12 patients solely because of the development of local skin erosion. This represents a 7.7% incidence of pacemaker generator erosion. Tree units were removed within a 3-month interval following pacemaker implantation and were associated with positive bacterial cultures, theraby indicating an infectious cause. Findings at removal of the remaining 13 pacemaker generators included extensive fibrosis with chronic inflammation, fibroblastic proliferation, and granulation tissue, which was most prominent at the site of insertion of the pacemaker lead into the pacemaker generator unit. Granulation tissue frequently led from this area to the area of skin attenuation and erythema. Inspection of the pacemaker generator units and electrodes demonstrated fluid ingress and tissue ingrowth toward the electrode due to inadequate seal mechanisms. Inadequate seal design of the pacemaker generator and electrode junction leads to tissue ingrowth with fibroblastic proliferatiog chronic inflammation, and eventual pacemaker erosion. PMID:496497

  19. Cardiac arrest in kearns-sayre syndrome.

    PubMed

    van Beynum, Ingrid; Morava, Eva; Taher, Marjan; Rodenburg, Richard J; Karteszi, Judit; Toth, Kalman; Szabados, Eszter

    2012-01-01

    The prognosis of progressive ophthalmoplegia in patients with large-scale mitochondrial DNA deletions is highly variable and almost unpredictable. The risk to develop cardiac involvement and sudden cardiac death is strikingly high, especially in patients with Kearns-Sayre syndrome (KSS). The most typical cardiac complications of the disease are conduction defects, which usually begin with left anterior fascicular block with or without right bundle branch block (RBBB), progressing sometimes rapidly to complete atrioventricular block. Other cardiac manifestations reported are first or second degree of AV block, QT prolongation, torsades de pointes ventricular tachycardia, and rarely dilated cardiomyopathy. Most frequently syncope, sometimes even sudden cardiac death, is the first clinical sign of the cardiac disease in KSS. Due to these life-threatening cardiac conditions, patients should be carefully monitored for cardiac signs and symptoms and pacemaker implantation should be suggested early to avoid sudden cardiac arrest in KSS.Here, we present two cases of KSS with life-threatening syncope due to complete atrioventricular block. To emphasize the importance of an early pacemaker implantation, we review the literature on cardiac complications in KSS in the last 20 years. In almost all of the reviewed cases, ophthalmoplegia or ptosis was present before the cardiac manifestations. In most of the cases, syncope was the first symptom of the cardiac involvement. There was no correlation between the age of the onset of the disease and the onset of cardiac manifestations.With our current report, we increase awareness for life-threatening cardiac complications in patients with KSS. PMID:23430846

  20. Measuring pacemaker dose: a clinical perspective.

    PubMed

    Studenski, Matthew T; Xiao, Ying; Harrison, Amy S

    2012-01-01

    Recently in our clinic, we have seen an increased number of patients presenting with pacemakers and defibrillators. Precautions are taken to develop a treatment plan that minimizes the dose to the pacemaker because of the adverse effects of radiation on the electronics. Here we analyze different dosimeters to determine which is the most accurate in measuring pacemaker or defibrillator dose while at the same time not requiring a significant investment in time to maintain an efficient workflow in the clinic. The dosimeters analyzed here were ion chambers, diodes, metal-oxide-semiconductor field effect transistor (MOSFETs), and optically stimulated luminescence (OSL) dosimeters. A simple phantom was used to quantify the angular and energy dependence of each dosimeter. Next, 8 patients plans were delivered to a Rando phantom with all the dosimeters located where the pacemaker would be, and the measurements were compared with the predicted dose. A cone beam computed tomography (CBCT) image was obtained to determine the dosimeter response in the kilovoltage energy range. In terms of the angular and energy dependence of the dosimeters, the ion chamber and diode were the most stable. For the clinical cases, all the dosimeters match relatively well with the predicted dose, although the ideal dosimeter to use is case dependent. The dosimeters, especially the MOSFETS, tend to be less accurate for the plans, with many lateral beams. Because of their efficiency, we recommend using a MOSFET or a diode to measure the dose. If a discrepancy is observed between the measured and expected dose (especially when the pacemaker to field edge is <10 cm), we recommend analyzing the treatment plan to see whether there are many lateral beams. Follow-up with another dosimeter rather than repeating multiple times with the same type of dosimeter. All dosimeters should be placed after the CBCT has been acquired. PMID:21875785

  1. Measuring pacemaker dose: A clinical perspective

    SciTech Connect

    Studenski, Matthew T., E-mail: matthew.studenski@jeffersonhospital.org [Department of Radiation Oncology at the Jefferson Medical College and Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA (United States); Xiao Ying; Harrison, Amy S. [Department of Radiation Oncology at the Jefferson Medical College and Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA (United States)

    2012-07-01

    Recently in our clinic, we have seen an increased number of patients presenting with pacemakers and defibrillators. Precautions are taken to develop a treatment plan that minimizes the dose to the pacemaker because of the adverse effects of radiation on the electronics. Here we analyze different dosimeters to determine which is the most accurate in measuring pacemaker or defibrillator dose while at the same time not requiring a significant investment in time to maintain an efficient workflow in the clinic. The dosimeters analyzed here were ion chambers, diodes, metal-oxide-semiconductor field effect transistor (MOSFETs), and optically stimulated luminescence (OSL) dosimeters. A simple phantom was used to quantify the angular and energy dependence of each dosimeter. Next, 8 patients plans were delivered to a Rando phantom with all the dosimeters located where the pacemaker would be, and the measurements were compared with the predicted dose. A cone beam computed tomography (CBCT) image was obtained to determine the dosimeter response in the kilovoltage energy range. In terms of the angular and energy dependence of the dosimeters, the ion chamber and diode were the most stable. For the clinical cases, all the dosimeters match relatively well with the predicted dose, although the ideal dosimeter to use is case dependent. The dosimeters, especially the MOSFETS, tend to be less accurate for the plans, with many lateral beams. Because of their efficiency, we recommend using a MOSFET or a diode to measure the dose. If a discrepancy is observed between the measured and expected dose (especially when the pacemaker to field edge is <10 cm), we recommend analyzing the treatment plan to see whether there are many lateral beams. Follow-up with another dosimeter rather than repeating multiple times with the same type of dosimeter. All dosimeters should be placed after the CBCT has been acquired.

  2. Magnetic resonance imaging safety in pacemaker and implantable cardioverter defibrillator patients: how far have we come?

    PubMed

    Nordbeck, Peter; Ertl, Georg; Ritter, Oliver

    2015-06-21

    Magnetic resonance imaging (MRI) has long been regarded a general contraindication in patients with cardiovascular implanted electronic devices such as cardiac pacemakers or cardioverter defibrillators (ICDs) due to the risk of severe complications and even deaths caused by interactions of the magnetic resonance (MR) surrounding and the electric devices. Over the last decade, a better understanding of the underlying mechanisms responsible for such potentially life-threatening complications as well as technical advances have allowed an increasing number of pacemaker and ICD patients to safely undergo MRI. This review lists the key findings from basic research and clinical trials over the last 20 years, and discusses the impact on current day clinical practice. With 'MR-conditional' devices being the new standard of care, MRI in pacemaker and ICD patients has been adopted to clinical routine today. However, specific precautions and specifications of these devices should be carefully followed if possible, to avoid patient risks which might appear with new MR technology and further increasing indications and patient numbers. PMID:25796053

  3. Magnetic resonance imaging safety in pacemaker and implantable cardioverter defibrillator patients: how far have we come?

    PubMed Central

    Nordbeck, Peter; Ertl, Georg; Ritter, Oliver

    2015-01-01

    Magnetic resonance imaging (MRI) has long been regarded a general contraindication in patients with cardiovascular implanted electronic devices such as cardiac pacemakers or cardioverter defibrillators (ICDs) due to the risk of severe complications and even deaths caused by interactions of the magnetic resonance (MR) surrounding and the electric devices. Over the last decade, a better understanding of the underlying mechanisms responsible for such potentially life-threatening complications as well as technical advances have allowed an increasing number of pacemaker and ICD patients to safely undergo MRI. This review lists the key findings from basic research and clinical trials over the last 20 years, and discusses the impact on current day clinical practice. With ‘MR-conditional’ devices being the new standard of care, MRI in pacemaker and ICD patients has been adopted to clinical routine today. However, specific precautions and specifications of these devices should be carefully followed if possible, to avoid patient risks which might appear with new MR technology and further increasing indications and patient numbers. PMID:25796053

  4. Creating cost-efficient initiatives in social work practice in the cardiac program of an acute care hospital.

    PubMed

    Kohm, C; Pollinger, D N; Sheriff, F

    2000-05-01

    All three cost-saving initiatives--the creation of a one-page application form to streamline the rehabilitation application process, the use of the resource specialist to assist with applications, and the development of an information package on cardiac rehabilitation--reflect a process whereby a creative idea, generating planning, activities, and follow-up resulted in a measurable effective change in practice. This process truly translated strategy into action (Kaplan, 1996) and is vital to the current rethinking in health care of how best to do our work (Coan, 1994). Because of this process, social workers in the cardiovascular surgical division of the cardiac program are better equipped to respond to the psychosocial needs of a growing cardiac population in a fiscally restrained environment. PMID:10845150

  5. 77 FR 39924 - Effective Date of Requirement for Premarket Approval for Cardiovascular Permanent Pacemaker...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-06

    ...for Premarket Approval for Cardiovascular Permanent Pacemaker Electrode...protocol (PDP) for the cardiovascular permanent pacemaker electrode...established a comprehensive system for the regulation of medical...completion of a PDP for the cardiovascular permanent pacemaker...

  6. Pacemaker lead erosion simulating "Loch Ness Monster": conservative management.

    PubMed

    Garg, Naveen; Moorthy, Nagaraja

    2012-12-01

    The majority of pacemaker pocket or lead erosions are due to either mechanical erosion by the bulky pulse generator or secondary to pacemaker pocket infection. We describe an unusual case of delayed pacemaker lead erosion causing extrusion of a portion of the pacing lead, with separate entry and exit points, with the gap filled with new skin formation, simulating the "Loch Ness Monster", which was successfully managed conservatively by surgical reinsertion. PMID:23284119

  7. Electrophysiology and pacemaker function of the developing sinoatrial node.

    PubMed

    Baruscotti, Mirko; Robinson, Richard B

    2007-11-01

    The sinoatrial node performs its task as a cardiac impulse generator throughout the life of the organism, but this important function is not a constant. Rather, there are significant developmental changes in the expression and function of ion channels and other cellular elements, which lead to a postnatal slowing of heart rate and may be crucial to the reliable functioning of the node during maturation. In this review, we provide an overview of current knowledge regarding these changes, with the main focus placed on maturation of the ion channel expression profile. Studies on Na(+) and pacemaker currents have shown that their contribution to automaticity is greater in the newborn than in the adult, but this age-dependent decrease is at least partially opposed by an increased contribution of L-type Ca(2+) current. Whereas information regarding age-dependent changes in other transmembrane currents within the sinoatrial node are lacking, there are data on other relevant parameters. These include an increase in the nodal content of fibroblasts and in the area of nonexpression of connexin43, considered a molecular marker of nodal tissue. Although much remains to be done before a comprehensive view of the developmental biology of the node is available, important evidence in support of a molecular interpretation of developmental slowing of the intrinsic sinoatrial rate is beginning to emerge. PMID:17827259

  8. Stochastic Aspects of Cardiac Arrhythmias

    NASA Astrophysics Data System (ADS)

    Lerma, Claudia; Krogh-Madsen, Trine; Guevara, Michael; Glass, Leon

    2007-07-01

    Abnormal cardiac rhythms (cardiac arrhythmias) often display complex changes over time that can have a random or haphazard appearance. Mathematically, these changes can on occasion be identified with bifurcations in difference or differential equation models of the arrhythmias. One source for the variability of these rhythms is the fluctuating environment. However, in the neighborhood of bifurcation points, the fluctuations induced by the stochastic opening and closing of individual ion channels in the cell membrane, which results in membrane noise, may lead to randomness in the observed dynamics. To illustrate this, we consider the effects of stochastic properties of ion channels on the resetting of pacemaker oscillations and on the generation of early afterdepolarizations. The comparison of the statistical properties of long records showing arrhythmias with the predictions from theoretical models should help in the identification of different mechanisms underlying cardiac arrhythmias.

  9. Metabolic aspects of the rhythmogenesis in Aplysia pacemaker neurons

    Microsoft Academic Search

    C. F. Chen; R. Baumgarten; O. Harth

    1973-01-01

    Completely isolatedAplysia pacemaker neurons were used to investigate mechanisms of endogenous electrical rhythmicity. This preparation allows the study of pure pacemaker activity free from synaptic, ephaptic and\\/or humoral influences from the surrounding cells. The effect of some substances quite different in their mode of biochemical action were tested: sodium iodoacetate, phloridzin, dinitrophenol, heavy water, and ouabain. Each of these substances

  10. Reentrainment of the Circadian Pacemaker through Three Distinct Stages

    Microsoft Academic Search

    Tiecheng Liu; Jimo Borjigin

    2005-01-01

    Circadian rhythms are endogenously generated by a central pacemaker and are synchronized to the environmental LD cycle. The rhythms can be resynchronized, or reentrained, after a shift of the LD cycle, as in traveling across time zones. The authors have performed high-resolution mapping of the pacemaker to analyze the reentrainment process using rat pineal melatonin onset (MTon) and melatonin offset

  11. Microgenerators for Energy Autarkic Pacemakers and Defibrillators: Fact or Fiction?

    Microsoft Academic Search

    Günter Görge; Michael Kirstein; Raimund Erbel

    2001-01-01

    Background: Implantable devices for medical use like permanent pacemakers, defibrillators, and fluid pumps depend on an energy provided by batteries. Unfortunately, the battery usually determines the duration of life of these devices, while technical problems occur infrequent. Device replacement for battery exhaustion requires surgical procedures and account for up to 1\\/3 of all pacemakers sold. Attempts to provide unlimited power

  12. Nonlinear dynamics, chaos and complex cardiac arrhythmias

    NASA Technical Reports Server (NTRS)

    Glass, L.; Courtemanche, M.; Shrier, A.; Goldberger, A. L.

    1987-01-01

    Periodic stimulation of a nonlinear cardiac oscillator in vitro gives rise to complex dynamics that is well described by one-dimensional finite difference equations. As stimulation parameters are varied, a large number of different phase-locked and chaotic rhythms is observed. Similar rhythms can be observed in the intact human heart when there is interaction between two pacemaker sites. Simplified models are analyzed, which show some correspondence to clinical observations.

  13. Investigation of the bnp level changes in blood stream in different modes and lead locations after pacemaker implementation.

    PubMed

    Dehnavi, Alireza Mehri; Fakhrpour, Afshin; Tavakoli, Mohamad Bagher; Nikoo, Mohamad Hossein

    2012-01-01

    As has been proven, increase of mechanical strain could result in an increase of brain natriuretic peptide (BNP) in the blood stream of implanted patient pacemakers. We measured the BNP concentration in blood due to different mode and lead implantation location of pacemaker in the time period of 3 months. The aim of this study was to investigate the changing trend of BNP level after pacemaker implantation. One hundred and three pacemaker implanted patients were monitored. Patients were in the age span of 54±12 years, including 48 men and 55 women. A group of 44 were programmed in Dual Chamber Rate Adaptive (DDDR) Pacemaker mode and a group of 59 were programmed in Ventricular Rate Modulated Pacing (VVIR) mode by the recommendation of the cardiologist. Between these two groups, the pacing levels of pacemakers was divided to under and above 50%. Some of these pacemaker leads were located at the apex of the right ventricle and the others were located in the septum wall in the right ventricle. To evaluate BNP changes during a period of 3 months, the BNPs were measured in pg/ml within 24 h of implantation (BNP1) and after 3 months (BNP2). For different classes of pacemaker implantations, the ratio of final measurement (BNP2) is divided to after implantation measurements (BNP1). Results showed that in VVIR mode, the ratio is 1.54±0.3 and in DDDR mode, the ratio is 0.38±0.17, with acceptable standard error means (<0.04). Also, comparisons are made for lead location at two modes of DDDR and VVIR separately. In the DDDR mode, the ratio for apex location is 0.49±0.12 and for septum location is 0.22±0.34, with acceptable standard error means (<0.02). In the VVIR mode, the ratio for apex location is 1.71±0.27 and for septum location is 1.28±0.09, with acceptable standard error means (<0.04). Therefore, BNP decrease in DDDR mode is more than in VVIR mode programming. In both cases of DDDR and VVIR modes, the septum location of the leads would result in a greater decrease of BNP. PMID:23492826

  14. Return to flight status after cardiac rehabilitation: three case histories.

    PubMed

    Dwyer, J

    2001-01-01

    A pilot's license to operate aircraft is not valid unless it is accompanied by a medical certificate. This certificate is revoked if a pilot is diagnosed with a cardiovascular illness. After a lengthy waiting period, the medical certificate may be reinstated if the pilot meets rigid standards. For many pilots, participation in a cardiac rehabilitation program is essential to achieve the minimal functional capacity in exercise testing (10.0 metabolic equivalents), document tolerance of medications, and achieve successful rehabilitation. Our staff has assisted 11 pilots in their quest to resume commercial or recreational flying after heart surgery, pacemaker implantation, or angioplasty. This article summarizes the case histories of three pilots who returned to fight status, in three Federal Aviation Administration categories (FAA), after a cardiac illness. The principle goals of our rehabilitation program for pilots are: (1) to achieve the highest possible outcome of the rehabilitation process; (2) to establish a safe and effective independent exercise program; (3) to obtain measures of compliance and success with the independent exercise program; (4) to document tolerance of medications and ensure that medications are acceptable to the FAA; (5) to document stability of the serum glucose in diabetic patients engaged in rigorous, prolonged exercise; and (6) prepare the patient for performance of a treadmill test in which 100% predicted maximum heart rate is achieved without symptoms of cardiovascular distress. An inherent effect of pursuing these goals is dramatic risk factor modification including improved blood pressure and lipid status and reduced body mass index. After resumption of flying, none of our pilot-patients have experienced cardiac symptoms during flight, nor have they required emergency department visits or hospitalization for any reason. PMID:11591042

  15. What Is Cardiac Rehabilitation?

    MedlinePLUS

    ... special help in making lifestyle changes. During your rehabilitation program you’ll… • Have a medical evaluation to ... rate, blood pressure and EKG monitored. A cardiac rehabilitation (rehab) program takes place in a hospital or ...

  16. Improved cardiac management with a disease management program incorporating comprehensive lipid profiling.

    PubMed

    McAna, John F; Goldfarb, Neil I; Couto, Joseph; Henry, Michelle A; Piefer, Gary; Rapier, George M

    2012-02-01

    The objective of this study was to evaluate the improved effectiveness of a disease management treatment protocol incorporating comprehensive lipid profiling and targeted lipid care based on lipid profile findings in patients with ischemic heart disease (IHD) or congestive heart failure (CHF) enrolled in a managed care plan. This retrospective cohort study, conducted over a 2-year period, compared outcomes between patients with a standard lipid profile to those evaluated with a comprehensive lipid profile. All adult members of the WellMed Medical Management, Inc. managed care health plan diagnosed with IHD or CHF, and continuously enrolled between July 1, 2006 and June 30, 2008, were included in the study. Cases were defined as those who had at least 1 comprehensive lipid test (the VAP [vertical auto profile] ultracentrifuge test) during this period (n=1767); they were compared to those who had no lipid testing or traditional standard lipid testing only (controls, n=289). Univariate statistics were analyzed to describe the groups, and bivariate t tests or chi-squares examined differences between the 2 cohorts. Multivariate regression analyses were performed to control for potential confounders. The results show that the case group had lower total costs ($4852.62 vs. $7413.18; P=0.0255), fewer inpatient stays (13.1% vs. 18.3% of controls; P=0.0175) and emergency department visits (11.9% vs. 15.6% of controls; P=0.0832). Prescription use and frequency of lipid measurement suggested improved control resulting from a targeted approach to managing specific dyslipidemias. A treatment protocol incorporating a comprehensive lipid profile appears to improve care and reduce utilization and costs in a disease management program for cardiac patients. PMID:22166083

  17. Preliminary experience with the use of a programmable pacemaker.

    PubMed

    Morse, D; Fernandez, J; Samuel, A; Lemole, G; Parsonnet, V

    1975-05-01

    One hundred sixty-four patients, in whom new externally programmable pacemakers had been inserted, were studied over a two year period, beginning July, 1972. Following implantation, the rate and current output of this pacemaker could be changed at any time by a non-invasive technique involving electromagnetic pulse trains emitted by an external "programmer". In 89 percent of the patients it was possible to reduce battery output by half, implying greater longevity of the pacer in these cases. In 15 percent of the patients, manipulative control of the pacemaker rate was employed and found beneficial. PMID:1126191

  18. Urinary tract pacemaker cells: current knowledge and insights from nonrenal pacemaker cells provide a basis for future discovery.

    PubMed

    Feeney, Meghan M; Rosenblum, Norman D

    2014-04-01

    Coordinated ureteric peristalsis propels urine from the kidney to the bladder. Cells in the renal pelvis and ureter spontaneously generate and propagate electrical activity to control this process. Recently, c-kit tyrosine kinase and hyperpolarization-activated cyclic nucleotide-gated channel 3 (HCN3) were identified in the upper urinary tract. Both of these proteins are required for coordinated proximal to distal contractions in the ureter. Alterations in pacemaker cell expression are present in multiple congenital kidney diseases, suggesting a functional contribution by these cells to pathologic states. In contrast to gut and heart pacemaker cells, the developmental biology of ureteric pacemaker cells, including cell lineage and signaling mechanisms, is undefined. Here, we review pacemaker cell identify and function in the urinary pelvis and ureter and the control of pacemaker function by Hedgehog-GLI signaling. Next, we highlight current knowledge of gut and heart pacemaker cells that is likely to provide insight into developmental mechanisms that could control urinary pacemaker cells. PMID:24129851

  19. Evaluation of a Standardized Patient Education Program for Inpatient Cardiac Rehabilitation: Impact on Illness Knowledge and Self-Management Behaviors up to 1 Year

    ERIC Educational Resources Information Center

    Meng, Karin; Seekatz, Bettina; Haug, Günter; Mosler, Gabriele; Schwaab, Bernhard; Worringen, Ulrike; Faller, Hermann

    2014-01-01

    Patient education is an essential part of the treatment of coronary heart disease in cardiac rehabilitation. In Germany, no standardized and evaluated patient education programs for coronary heart disease have been available so far. In this article, we report the evaluation of a patient-oriented program. A multicenter quasi-experimental,…

  20. Cardiac Rehabilitation After Acute Myocardial Infarction Resuscitated From Cardiac Arrest

    PubMed Central

    Kim, Chul; Choi, Hee Eun; Kang, Seong Hoon

    2014-01-01

    Objective To examine the safety and effectiveness of cardiac rehabilitation on patients resuscitated from cardiac arrest due to acute myocardial infarction. Methods The study included 23 subjects, including 8 with history of cardiac arrest and 15 without history of cardiac arrest. Both groups underwent initial graded exercise test (GXT) and subsequent cardiac rehabilitation for 6 weeks. After 6 weeks, both groups received follow-up GXT. Results Statistically significant (p<0.05) increase of VO2peak and maximal MVO2 but significant (p<0.05) decrease of submaximal MVO2 and resting heart rate were observed in both groups after 6 weeks of cardiac rehabilitation. An increasing trend of maximal heart rates was observed in both groups. However, the increase was not statistically significant (p>0.05). There was no statistically significant change of resting heart rate, maximal heart rate, maximal MVO2, or submaximal MVO2 in both groups after cardiac rehabilitation. Fatal cardiac complications, such as abnormal ECG, cardiac arrest, death or myocardial infarction, were not observed. All subjects finished the cardiac rehabilitation program. Conclusion Improvement was observed in the exercise capacity of patients after aerobic exercise throughout the cardiac rehabilitation program. Therefore, cardiac rehabilitation can be safely administered for high-risk patients with history of cardiac arrest. Similar improvement in exercise capacity can be expected in patients without cardiac arrest experience. PMID:25566479

  1. Intracardiac Origin of Heart Rate Variability, Pacemaker Funny Current and their Possible Association with Critical Illness

    PubMed Central

    Papaioannou, Vasilios E; Verkerk, Arie O; Amin, Ahmed S; de Bakker, Jaques MT

    2013-01-01

    Heart rate variability (HRV) is an indirect estimator of autonomic modulation of heart rate and is considered a risk marker in critical illness, particularly in heart failure and severe sepsis. A reduced HRV has been found in critically ill patients and has been associated with neuro-autonomic uncoupling or decreased baroreflex sensitivity. However, results from human and animal experimental studies indicate that intracardiac mechanisms might also be responsible for interbeat fluctuations. These studies have demonstrated that different membrane channel proteins and especially the so-called ‘funny’ current (If), an hyperpolarization-activated, inward current that drives diastolic depolarization resulting in spontaneous activity in cardiac pacemaker cells, are altered during critical illness. Furthermore, membrane channels kinetics seem to have significant impact upon HRV, whose early decrease might reflect a cellular metabolic stress. In this review article we present research findings regarding intracardiac origin of HRV, at the cellular level and in both isolated sinoatrial node and whole ex vivo heart preparations. In addition, we will review results from various experimental studies that support the interrelation between If and HRV during endotoxemia. We suggest that reduced HRV during sepsis could also be associated with altered pacemaker cell membrane properties, due to ionic current remodeling. PMID:22920474

  2. Properties of the pacemaker current (If) in latent pacemaker cells isolated from cat right atrium.

    PubMed Central

    Zhou, Z; Lipsius, S L

    1992-01-01

    1. Single latent pacemaker cells were isolated from the Eustachian ridge of cat right atrium using Langendorff perfusion and enzyme dispersion techniques. Whole-cell patch-clamp techniques were used to study the hyperpolarization-activated inward current (I(f)). 2. All cells studied beat rhythmically. Pacemaker activity was recorded in the voltage range -68 +/- 1 to -54 +/- 2 mV and its cycle length was 901 +/- 67 ms (72 +/- 5 beats min-1) at 34-36 degrees C. Cells were elongated with tapered ends, and appeared bent or crinkled without obvious striations. Mean cell diameter and length were 7.4 +/- 0.5 microns and 93.1 +/- 5.9 microns, respectively (n = 15). Input resistance and total membrane capacitance were 2.2 +/- 0.2 G omega and 27.8 +/- 3.1 pF, respectively. 3. Hyperpolarizing clamp steps more negative than -50 mV elicited a time-dependent increasing inward current that was maximally activated at -120 mV. Activation of I(f) was well within the pacemaker voltage range. Half-maximal activation voltage and slope factor were calculated, using a Boltzmann function, to be -80.5 mV and 8.4, respectively. 4. The fully activated current-voltage (I-V) relationship was approximately linear at voltages more negative than -30 mV and showed outward rectification at more positive voltages. The reversal potential of I(f) was -26 mV and the fully activated conductance was 1.75 +/- 0.14 nS (n = 21). Caesium (2 mM) blocked I(f) at voltages more negative than the reversal potential. Reducing extracellular Na+ or K+ shifted the reversal potential more negative, and increasing extracellular K+ exerted the opposite effect. Reducing extracellular Na+ decreased I(f) amplitude and the slope of the fully activated I-V relationship, and elevated extracellular K+ increased I(f) amplitude and the slope of the fully activated I-V relationship. 5. Some pacemaker cells exhibited a short delay in the onset of I(f) activation whereas other pacemaker cells exhibited little, if any, delay in activation. I(f) currents exhibiting no delay in activation were best fitted by a single exponential function with a mean time constant of 3.20 +/- 1.03 s at -70 mV (n = 4). 6. A nystatin-permeabilized patch recording method was used to record spontaneous pacemaker action potentials and I(f) from the same pacemaker cell. Caesium (2 mM) inhibited I(f) by more than 90% (at -70 mV), and decreased the slope of diastolic depolarization, resulting in a 48 +/- 5% decrease in spontaneous rate.(ABSTRACT TRUNCATED AT 400 WORDS) Images Fig. 1 PMID:1281505

  3. Treatment strategy for infections in patients with permanent pacemakers

    Microsoft Academic Search

    Atsushi Morishita; Tadayuki Shimakura; Masaki Nonoyama; Taiichi Takasaki

    2001-01-01

    Infection after pacemaker implantation can be the most lethal potential complication, although such infections occur infrequently.\\u000a In this report, we review our experience with patients who were infected after pacemaker implantation and assess their treatment.\\u000a The infection rate was 1.3% (9 patients) after 712 operations performed in 588 patients. Four men and five women were infected;\\u000a their mean age was

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

    PubMed Central

    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

    Background 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. Methods and Results 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). Conclusions 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. PMID:26075602

  5. Pacemaker endocarditis caused by Propionibacterium acnes in an adult patient with Ebstein's anomaly: a report of a rare case.

    PubMed

    Santo, Karla R E; Franceschi, Vinicius; Campos, André C B; Monteiro, Thaíssa S; Barbosa, Giovanna I F; Dantas, Angela; Lamas, Cristiane C

    2014-10-01

    We report a rare case of a Brazilian adult woman with Ebstein's Anomaly who presented with pacemaker endocarditis caused by Propionibacterium acnes. Ebstein's Anomaly is a rare congenital malformation of the heart. Infective endocarditis is defined as an infection of heart valves, of the mural endocardium, of a septal defect, or of a cardiac electronic implantable device. Propionibacterium acnes is a skin commensal bacterium, that is usually considered as a contaminant, but can, on rare occasions, cause serious infections including endocarditis of prosthetic valves, native valves and cardiac electronic implantable devices. Diagnosis was made after nearly two years of investigation by identification of the organism by the MALDI-TOF technique and transoesophageal echocardiogram. The patient was successfully treated with daptomycin and device removal. She remains free of endocarditis after 32 months of follow-up. PMID:25047281

  6. Surgical Management of the Patient with an Implanted Cardiac Device

    PubMed Central

    Madigan, John D.; Choudhri, Asim F.; Chen, Jonathan; Spotnitz, Henry M.; Oz, Mehmet C.; Edwards, Niloo

    1999-01-01

    Objective To identify the sources of electromagnetic interference (EMI) that may alter the performance of implanted cardiac devices and develop strategies to minimize their effects on patient hemodynamic status. Summary Background Data Since the development of the sensing demand pacemaker, EMI in the clinical setting has concerned physicians treating patients with such devices. Implanted cardiovertor defibrillators (ICDs) and ventricular assist devices (VADs) can also be affected by EMI. Methods All known sources of interference to pacemakers, ICDs, and VADs were evaluated and preventative strategies were devised. Results All devices should be thoroughly evaluated before and after surgery to make sure that its function has not been permanently damaged or changed. If electrocautery is to be used, pacemakers should be placed in a triggered or asynchronous mode; ICDs should have arrhythmia detection suspended before surgery. If defibrillation is to be used, the current flow between the paddles should be kept as far away from and perpendicular to the lead system as possible. Both pacemakers and ICDs should be properly shielded if magnetic resonance imaging, positron emission tomography, or radiation therapy is to be used. The effect of EMI on VADs depends on the model. Magnetic resonance imaging adversely affects all VADs except the Abiomed VAD, and therefore its use should be avoided in this population of patients. Conclusions The patient with an implanted cardiac device can safely undergo surgery as long as certain precautions are taken. PMID:10561087

  7. Radioisotope thermoelectric generators for implanted pacemakers

    SciTech Connect

    Pustovalov, A.A.; Bovin, A.V.; Fedorets, V.I.; Shapovalov, V.P.

    1986-08-01

    This paper discusses the development and application of long-life lithium batteries and the problems associated with miniature radioisotope thermoelectric generators (RITEG) with service lives of 10 years or longer. On eof the main problems encountered when devising a radioisotope heat source (RHS) for an RITEG is to obtain biomedical /sup 238/PuO/sub 2/ with a specific neutron yield of 3.10/sup 3/-4.10/sup 3/ (g /SUP ./ sec)/sup -1/, equivalent to metallic Pu 238, and with a content of gamma impurities sufficient to ensure a permissible exposure a permissible exposure does rate (EDR) of a mixture of neutron and gamma radiation. After carrying out the isotope exchange and purifying the initial sample of its gamma impurity elements, the authors obtain biomedical Pu 238 satisfying the indicated requirements king suitable for use in the power packs of medical devices. Taking the indicated specifications into account, the Ritm-1o and gamma radioisotope heat sources were designed, built, tested in models and under natural conditions, and then into production as radioisotope thermoelectric generators designed to power the electronic circuits of implanted pacemakers. The Ritm-MT and Gemma radioisotope thermoelectric generators described are basic units, which can be used as self-contained power supplies for electronic equipment with power requirements in the micromilliwatt range.

  8. A coupled SYSTEM of intracellular Ca2+ clocks and surface membrane voltage clocks controls the timekeeping mechanism of the heart’s pacemaker

    PubMed Central

    Lakatta, Edward G.; Maltsev, Victor A.; Vinogradova, Tatiana M.

    2010-01-01

    Ion channels on the surface membrane of sinoatrial nodal pacemaker cells (SANC) are the proximal cause of an action potential. Each individual channel type has been thoroughly characterized under voltage clamp, and the ensemble of the ion channel currents reconstructed in silico generates rhythmic action potentials. Thus, this ensemble can be envisioned as a surface “membrane clock” (M clock). Localized subsarcolemmal Ca2+ releases are generated by the sarcoplasmic reticulum via ryanodine receptors during late diastolic depolarization and are referred to as an intracellular “Ca2+ clock”, because their spontaneous occurrence is periodic during voltage clamp or in detergent-permeabilized SANC, and in silico as well. In spontaneously firing SANC, the M and Ca2+ clocks do not operate in isolation, but work together via numerous interactions modulated by membrane voltage, subsarcolemmal Ca2+, and PKA and CaMKII-dependent protein phosphorylation. Through these interactions the two subsystem clocks become mutually entrained to form a robust, stable, coupled-clock system that drives normal cardiac pacemaker cell automaticity. G-protein coupled-receptors signaling creates pacemaker flexibility, i.e. effects changes in the rhythmic action potential firing rate, by impacting on these very same factors that regulate robust basal coupled-clock system function. This review examines evidence that forms the basis of this coupled-clock system concept in cardiac SANC. PMID:20203315

  9. Signature Program/Landmark Research Programs

    E-print Network

    owned animals with naturally occurring heart disease (e.g., Doberman pinschers with dilated of the Michael E. DeBakey Institute that was created in 1999 to formalize programmatic relationship between units interventional cardiac studies (e.g., coronary stents, pacemakers). The importance of using animals

  10. An Evaluation of Technologies for Identifying Acute Cardiac Ischemia in the Emergency Department: A Report from a National Heart Attack Alert Program Working Group

    Microsoft Academic Search

    Harry P Selker; Robert J Zalenski; Elliott M Antman; Tom P Aufderheide; Sheilah Ann Bernard; Robert O Bonow; W. Brian Gibler; Michael D Hagen; Paula Johnson; Joseph Lau; Robert A McNutt; Joseph Ornato; J. Sanford Schwartz; Jane D Scott; Paul A Tunick; W. Douglas Weaver

    1997-01-01

    [Selker HP, Zalenski RJ, Antman EM, Aufderheide TP, Bernard SA, Bonow RO, Gibler WB, Hagen MD, Johnson P, Lau J, McNutt RA, Ornato J, Schwartz JS, Scott JD, Tunick PA, Weaver WD: An evaluation of technologies for identifying acute cardiac ischemia in the emergency department: A report from a National Heart Attack Alert Program Working Group. Ann Emerg Med January

  11. An Evaluation of Technologies for Identifying Acute Cardiac Ischemia in the Emergency Department: Executive Summary of a National Heart Attack Alert Program Working Group Report

    Microsoft Academic Search

    Harry P Selker; Robert J Zalenski; Elliott M Antman; Tom P Aufderheide; Sheilah Ann Bernard; Robert O Bonow; W. Brian Gibler; Michael D Hagen; Paula Johnson; Joseph Lau; Robert A McNutt; Joseph Ornato; J. Sanford Schwartz; Jane D Scott; Paul A Tunick; W. Douglas Weaver

    1997-01-01

    [Selker HP, Zalenski RJ, Antman EM, Aufderheide TP, Bernard SA, Bonow RO, Gibler WB, Hagen MD, Johnson P, Lau J, McNutt RA, Ornato J, Schwartz JS, Scott JD, Tunick PA, Weaver WD: An evaluation of technologies for identifying acute cardiac ischemia in the emergency department: Executive Summary of a National Heart Attack Alert Program Working Group report. Ann Emerg Med

  12. The Effects of a Cardiac Rehabilitation Program Tailored for Women on Their Perceptions of Health: A Randomized Clinical Trial

    PubMed Central

    Beckie, Theresa M.; Beckstead, Jason W.

    2010-01-01

    PURPOSE The aim of this study was to compare the effects of a cardiac rehabilitation (CR) program tailored for women to a traditional program on perceptions of health among women with coronary heart disease. METHODS This 2-group randomized clinical trial compared the perceptions of health among 92 women completing a traditional 12-week CR program to 133 women completing a tailored program that included motivational interviewing guided by the Transtheoretical model of behavior change. Perceptions of health were measured using the SF-36 health survey at baseline, post-intervention, and at 6-month follow-up. ANOVA was used to compare changes in SF-36 subscale scores over time. RESULTS The group by time interaction was significant for the general health (F(2,446) = 3.80, P=.023), social functioning (F(2,446) = 4.85, P=.008), vitality (F(2,446) = 5.85, P=.003), and mental health (F(2,446) = 3.61, P=.028), subscales indicating that the pattern of change was different between the 2 groups. Of the 4 subscales on which there were significant group by time interactions, the tailored group demonstrated improved scores over time on all 4 while the traditional group improved on only the emotional role limitations and vitality subscales. CONCLUSIONS A tailored CR program improved general health perceptions, mental health, vitality, and social functioning in women when compared to traditional CR. To the extent that perceptions of health contribute to healthy behaviors fostered in CR programs, tailoring CR programs to alter perceptions of health may improve adherence. PMID:21037482

  13. 76 FR 44872 - Effective Date of Requirement for Premarket Approval for an Implantable Pacemaker Pulse Generator

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-27

    ...8. Other Complications Other risks of pacemaker implantation include...myopotential sensing, and additional surgery for replacement. Risks are also associated with pacemaker...the Federal Food, Drug, and Cosmetic Act and under authority...

  14. Preliminary Test of a New Haemodynamic Pacemaker: Evaluation of Sensor Safety

    Microsoft Academic Search

    N. Galizio; J. Gonzalez; H. Fraguas; J. Barra; S. Graf; E. Forteza; R. Chirife; F. Gregorio

    In the present animal model study, the pacemaker Sophós 100 proved fully reliable in a 1 month follow-up period. TVI sensor operation did not interfere with conventional pacemaker functions, opening the way to its implantation in human beings.

  15. 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.

  16. Economic implications of infections of implantable cardiac devices in a single institution

    Microsoft Academic Search

    Christian Kuehn; Karolin Graf; Wieland Heuer; Andres Hilfiker; Iris F. Chaberny; Meike Stiesch; Axel Haverich

    2010-01-01

    Introduction: The use of medical devices, such as cardiac pacemakers, prosthetic heart valves and vascular prostheses, has become a routine treatment procedure in cardiovascular medicine. Unfortunately, bacterial infections of these devices are a serious and sometimes life-threatening for the patient, necessitating explantation. Despite implementing different prophylactic strategies to avoid contamination of the device, infections do occur. This study analysed the

  17. VDD pacing from the middle cardiac vein via a persistent left superior vena cava

    Microsoft Academic Search

    John A. Chiladakis; Dimitris Siablis; Antonis S. Manolis

    2001-01-01

    We report a combination of unusual features demonstrating a permanent pacemaker implantation of a single-pass VDD lead by way of an anomalous persistent left superior vena cava in the middle cardiac vein. The ventricular stimulation resembled a right bundle branch block QRS morphology and was successfully synchronized by spontaneous atrial activity. This case illustrates an alternative approach of effective VDD

  18. Sudden, unexpected death due to cardiac fibroma. Report of a case and review of the literature.

    PubMed

    Amr, S S; Al-Ragheb, S Y; Soleiman, N A; Al-Debs, N R

    1987-06-01

    A case of cardiac fibroma in a 58-year-old woman with a history of atrioventricular block is described. The patient died suddenly at home 6 days following the insertion of a pacemaker. Review of the pertinent literature is presented. PMID:3605010

  19. Cardiac asystole associated with epileptic seizures: a case report with simultaneous EEG and ECG.

    PubMed Central

    Howell, S J; Blumhardt, L D

    1989-01-01

    Cardiac arrhythmias occurring in association with epileptic seizures are a potential source of diagnostic confusion and a possible cause of sudden unexpected death in epilepsy. A case is described in which simultaneous ambulatory electroencephalography and electrocardiography revealed periods of asystole coinciding with epileptic seizures. The aystole appeared to precede obvious changes in the scalp recorded electroencephalogram (EEG), but clinical attacks and EEG seizure activity were not altered by pacemaker correction of the cardiac arrhythmias. PMID:2501457

  20. Concerns about sources of electromagnetic interference in patients with pacemakers.

    PubMed

    Sakakibara, Y; Mitsui, T

    1999-11-01

    Electromagnetic noise is rapidly increasing in our environment so electromagnetic interference (EMI) with pacemakers (PM) may become a more important problem despite technological improvements in PM. The aim of this study was to evaluate the kinds of EMI which affect the quality of life of PM patients. The participants (1,942 Japanese Association for Pacemaker Patients: Pacemaker-Tomonokai) were asked to respond to a questionnaire about their major EMI troubles, and 1,567 patients (80.7%) responded by mail. The main concerns were from mobile telephones (MT) (39%), magnetic resonance imaging (MRI) (17%), electronic kitchen appliances, automobile engines and high voltage power lines. If possible, PM implantation sites should be carefully selected not only according to the physician's convenience but also considering information on each patient's habits and physical limitations. PMID:10737557

  1. [Development and research of temporary demand pacemaker with electrocardiosignal display].

    PubMed

    Fan, Shounian; Jiang, Chenxi; Cai, Yunchang; Pan, Yangzhong; Yang, Tianhe; Wu, Qiang; Zheng, Yaxi; Liu, Xiaoqiao; Li, Shiying

    2004-08-01

    A temporary demand pacemaker with electrocardiosignal display is introduced in this paper. Double way low-noise electrocardiosignal preamplifier, amplitude limiter, high and low pass filter, 50 Hz notch filter, TTL level generator and stimulating pulse formation circuit are components of the hardware electrocircuit. The demand pacing and the electrocardiosignal display are separately controlled by the software in which the double microcontrollers communications technique is used. In this study, liquid crystal display is firstly used in body surface electrocardiosignal display or intracardial electrophysiologic signal display when the temporary demand pacemaker is installed and put into use. The machine has proven clinically useful and can be of wide appliation. PMID:15357453

  2. Measurement of functional capacity requirements of police officers to aid in development of an occupation-specific cardiac rehabilitation training program

    PubMed Central

    Schneider, Jonna; Hubbard, Matthew; McCullough-Shock, Tiffany; Cheng, Dunlei; Simms, Kay; Hartman, Julie; Hinton, Paul; Strauss, Danielle

    2010-01-01

    This study was designed to measure the functional capacity of healthy subjects during strenuous simulated police tasks, with the goal of developing occupation-specific training for cardiac rehabilitation of police officers. A calibrated metabolic instrument and an oxygen consumption data collection mask were used to measure the oxygen consumption and heart rates of 30 Dallas Police Academy officers and cadets as they completed an 8-event obstacle course that simulated chasing, subduing, and handcuffing a suspect. Standard target heart rates (85% of age-predicted maximum heart rate, or 0.85 × [220 – age]) and metabolic equivalents (METs) were calculated; a matched-sample t test based on differences between target and achieved heart rate and MET level was used for statistical analysis. Peak heart rates during the obstacle course simulation were significantly higher than the standard target heart rates (those at which treadmill stress tests in physicians' offices are typically stopped) (t29 = 12.81, P < 0.001) and significantly higher than the suggested maximum of 150 beats/min during cardiac rehabilitation training (t29 = 17.84, P < 0.001). Peak MET levels during the obstacle course simulation were also significantly higher than the goal level (8 METs) that patients typically achieve in a cardiac rehabilitation program (t29 = 14.73, P < 0.001). We conclude that police work requires a functional capacity greater than that typically attained in traditional cardiac rehabilitation programs. Rehabilitation professionals should consider performing maximal stress tests and increasing the intensity of cardiac rehabilitation workouts to effectively train police officers who have had a cardiac event. PMID:20157495

  3. Diabetes mellitus activates fetal gene program and intensifies cardiac remodeling and oxidative stress in aged spontaneously hypertensive rats

    PubMed Central

    2013-01-01

    Background The combination of systemic arterial hypertension and diabetes mellitus (DM) induces greater cardiac remodeling than either condition alone. However, this association has been poorly addressed in senescent rats. Therefore, this study aimed to analyze the influence of streptozotocin-induced DM on ventricular remodeling and oxidative stress in aged spontaneously hypertensive rats (SHR). Methods Fifty 18 month old male SHR were divided into two groups: control (SHR, n?=?25) and diabetic (SHR-DM, n?=?25). DM was induced by streptozotocin (40 mg/kg, i.p.). After nine weeks, the rats underwent echocardiography and myocardial functional study in left ventricular (LV) isolated papillary muscle preparations. LV samples were obtained to measure myocyte diameters, interstitial collagen fraction, and hydroxyproline concentration. Gene expression of atrial natriuretic peptide (ANP) and ?- and ?-myosin heavy chain (MyHC) isoforms was evaluated by RT-PCR. Serum oxidative stress was assessed by measuring lipid hydroperoxide concentration and superoxide dismutase and glutathione peroxidase activities. Statistics: Student’s t test or Mann-Whitney test, p?cardiac dilation and functional impairment, increases oxidative stress and activates fetal gene program in aged spontaneously hypertensive rats. PMID:24134628

  4. Bursting in Cellular Automata and Cardiac Arrhythmias

    NASA Astrophysics Data System (ADS)

    Bub, Gil; Shrier, Alvin; Glass, Leon

    2013-01-01

    The mechanisms underlying the initiation and continuation of abnormal cardiac arrhythmias are incompletely understood. In this chapter, we summarize work that shows how simple cellular automata models of excitable media can display a range of interesting dynamical behavior including spontaneous bursts of reentrant spiral activity. Since the model incorporates basic physiological properties of excitability, heterogeneity, localized pacemakers, and fatigue in a schematic way, the model captures generic physiological dynamics that should be broadly observed in experimental and clinical settings as well as in more realistic mathematical models.

  5. Clinical testing of a new pacemaker function to monitor ventricular capture.

    PubMed

    Alonso, Christine; Savouré, Arnaud; Jauvert, Gael; Casset, Cyrille; Ranaivoson, Hanta; Cazeau, Serge; Anselme, Frédéric

    2005-01-01

    Automatic beat-by-beat capture functions are designed to minimize the pacing energy delivered, while maintaining the highest safety by delivering an immediate back-up stimulus in case of loss of capture. The objective of this study was to estimate the lowering of ventricular pacing amplitude allowed by such a function, compared to amplitudes usually set manually in routine practice. An automatic ventricular pacing threshold test is launched every 6 hours to measure the automatic capture threshold (AT). From AT the function calculates: (1) the"capture amplitude"(V(c)) = AT + 0.5 V at a minimum output of 1 V and (2) the"safety amplitude" (V(s)) = twice AT at a minimum output of 2.5 V. The function preferentially uses V(c) and verifies capture after each paced beat. In case of loss of capture, a back-up spike is delivered and V(s) is implemented until the next threshold measurement. We estimated the ventricular amplitude delivered by the pacemaker from data stored in the pacemaker memory. We compared these values with the pacing amplitude typically programmed manually (MPA) by physicians at twice AT and a minimum of 2.5 V. Data from 57 recipients of Talent 3 DR pacemakers were analyzed. Complete data sets were available in 25 patients at 1 day, 28 at 1 month, and 39 between 1 day and 1 month. No loss of capture or ventricular pause was observed on 53 ambulatory electrocardiograms (ECG); and pulse amplitude automatically delivered by the device was significantly lower than the MPA at each of the three time points analyzed. This new beat-by-beat capture function allows a significant lowering of the pacing amplitude compared to manual settings, while preserving a 100% safety. PMID:15683521

  6. Properties of ivabradine-induced block of HCN1 and HCN4 pacemaker channels

    PubMed Central

    Bucchi, A; Tognati, A; Milanesi, R; Baruscotti, M; DiFrancesco, D

    2006-01-01

    Ivabradine is a ‘heart rate-reducing’ agent able to slow heart rate, without complicating side-effects. Its action results from a selective and specific block of pacemaker f-channels of the cardiac sinoatrial node (SAN). Investigation has shown that block by ivabradine requires open f-channels, is use dependent, and is affected by the direction of current flow. The constitutive elements of native pacemaker channels are the hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, of which four isoforms (HCN1–4) are known; in rabbit SAN tissue HCN4 is expressed strongly, and HCN1 weakly. In this study we have investigated the blocking action of ivabradine on mouse (m) HCN1 and human (h) HCN4 channels heterologously expressed in HEK 293 cells. Ivabradine blocked both channels in a dose-dependent way with half-block concentrations of 0.94 ? m for mHCN1 and 2.0 ? m for hHCN4. Properties of block changed substantially for the two channels. Block of hHCN4 required open channels, was strengthened by depolarization and was relieved by hyperpolarization. Block of mHCN1 did not occur, nor was it relieved, when channels were in the open state during hyperpolarization; block required channels to be either closed, or in a transitional state between open and closed configurations. The dependence of block upon current flow was limited for hHCN4, and not significant for mHCN1 channels. In summary our results indicate that ivabradine is an ‘open-channel’ blocker of hHCN4, and a ‘closed-channel’ blocker of mHCN1 channels. The mode of action of ivabradine on the two channels is discussed by implementing a simplified version of a previously developed model of f-channel kinetics. PMID:16484306

  7. Atypical pattern of lung involvement in pacemaker endocarditis.

    PubMed

    Ampatzidou, Fotini C; Sileli, Maria N; Koutsogiannidis, Charilaos-Panagiotis C; Ananiadou, Olga G; Madesis, Athanasios A; Michaelidis, Vassilis G; Drossos, George E

    2014-08-01

    Pacemaker endocarditis has a high rate of morbidity and mortality and is associated with substantial health-care cost. To maximize the effectiveness of treatment, diagnosis of pacemaker endocarditis should be made as early as possible. Medical treatment alone is not successful, and the removal of the entire artificial pacing system is often required. We present a case of a female patient with a permanent transvenous pacemaker, recurring episodes of fever and chills, general malaise, and a computed tomography image of a solitary tumor-like lesion indicating pneumonia. The symptoms subsided with empirical antibiotics but without improvement in the radiologic images. A wedge resection of the lesion by thoracotomy was performed, revealing a necrotic lung lesion compatible with pulmonary infarct. Transesophageal echocardiography showed a mass that was adherent to the pacemaker lead. The therapeutic approach consisted of surgical removal of the complete pacing system along with long-term antibiotic therapy and implantation of a new device with an epicardial lead. Serial follow-up echocardiograms for a 1-y period did not show any recurrence, and the subsequent course was uneventful. PMID:24194574

  8. A model of respiration rhythmogenesis bridging network and pacemaker theories

    Microsoft Academic Search

    Efstratios K. Kosmidis; Jean-françois Vibert

    2001-01-01

    Respiration generation occurs at the brainstem. It is still unclear if it relies on pacemaker units or on network properties. Using a computational model we show that the two theories are not mutually exclusive. Based on experimental data we propose a network architecture that takes advantage of noise to ignite and maintain the respiratory rhythm. We show that a population

  9. Cellular circadian pacemaking and the role of cytosolic rhythms.

    PubMed

    Hastings, Michael H; Maywood, Elizabeth S; O'Neill, John S

    2008-09-01

    The daily rhythms that adapt organisms to the solar cycle are driven by internal circadian clocks. The hypothesis that the core pacemakers of these clocks consist of auto-regulatory transcriptional/post-translational feedback loops (TTFLs) was first developed in flies and fungi and has now been extended successfully to describe circadian timing mechanisms in mammals and plants. TTFL models revolve around the protein products of 'clock' genes that feedback periodically to regulate their own expression. From this simple beginning, the models have been expanded to encompass multiple, interlinked loops. However, experimental data now highlight the limitations of the TTFL model. Until recently, the focus on transcription caused rhythms in cytosolic signalling pathways to be viewed as outputs of the 'core' transcriptional clockwork, or else as a mechanism for its entrainment by extra-cellular stimuli. Recent work in Arabidopsis thaliana, Drosophila melanogaster and mammals now reveals that cytosolic rhythms in small signalling molecules have a central role within the circadian pacemaker. The logic is consistent across taxa: oscillatory cytoplasmic elements integrate with transcriptional feedback loops to sustain them and determine their rhythmic properties. Thus, clock outputs can constitute inputs to subsequent cycles and so become indistinguishable from a core mechanism. This emphasises the interdependence of nuclear and cytoplasmic processes in circadian pacemaking, such that the pacemakers of some species might encompass the entire cell and its intercellular environment. PMID:18786386

  10. Pacemaker Related Infective Endocarditis from Staphylococcus Lugdunensis: A Case Report

    PubMed Central

    Ward, Michael; Boehm, Kevin M.

    2013-01-01

    Staphylococcus lugdunensis is a common skin flora not typically associated with infection. There are, however, several cases reported in the literature of Staphylococcus lugdunensis as a causative bacterium of various infections. This paper reports an additional case of pacemaker associated endocarditis with Staphylococcus lugdunensis as the causative bacterium. PMID:24829817

  11. Pacemaker lead infection: echocardiographic features, management, and outcome

    PubMed Central

    Victor, F; De Place, C; Camus, C; Le Breton, H; Leclercq, C; Pavin, D; Mabo, P; Daubert, C

    1999-01-01

    Objective—To compare transthoracic and transoesophageal echocardiography (TTE, TOE) in patients with permanent pacemaker lead infection and to evaluate the safety of medical extraction in cases of large vegetations.?Methods—TTE and TOE were performed in 23 patients with definite pacemaker lead infection. Seventeen patients without previous infection served as a TOE reference for non-infected leads.?Results—TTE was positive in seven cases (30%) whereas with TOE three different types of vegetations attached to the leads were visualised in 21 of the 23 cases (91%). Of the 20 patients with vegetations and lead culture, 17 (85%) had bacteriologically active infection. Left sided valvar endocarditis was diagnosed in two patients. In the control group, strands were visualised by TOE in five patients, and vegetations in none. Medical extraction of vegetations ? 10 mm was performed in 12 patients and was successful in nine (75%) without clinical pulmonary embolism. After 31.2 (19.1) months of follow up (mean (SD)), all patients except one were cured of infection; three died from other causes.?Conclusions—Combined with bacteriological data, vegetations seen on TOE strongly suggest pacemaker lead infection. Normal TTE examinations do not exclude this diagnosis because of its poor sensitivity. Medical extraction of even large vegetations appeared to be safe.?? Keywords: pacemaker lead infection;  transoesophageal echocardiography PMID:10220550

  12. Differentially timed extracellular signals synchronize pacemaker neuron clocks.

    PubMed

    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

    2014-09-01

    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

  13. 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

  14. A semi-automatic device for pacemaker function analysis.

    PubMed

    Behar, S; Fischler, H; Feldman, S; Neufeld, H N

    1980-01-01

    An external semi-automatic Pacemaker Function Analyzer (PFA) has been designed for routine examination (screening) of ambulatory-paced patients in general medical practice. The evaluation of the pacemaker (PM) function is based on recognition, decoding, and measurement of the occurrence of QRS complexes and pacing artifacts, and on logic processing of the decoded data. In this way, the state of the batteries and the integrity of the electronic circuitry and the electrodes can be determined. Other PFA applications concern supervision of hospitalized patients by interfacing the analyzer with the monitoring system of a Coronary Care Unit (CCU), transtelephone checking, and adaptation for use in specialized pacemaker clinics. The performance of the PFA was checked on 92 ambulatory patients. The PFA system recognized all but 0.29% of the QRS complexes and 0.21% of the pacing artifacts. Thirty-two of these patients were tested simultaneously by the PFA and the pacemaker clinic physician, both arriving at the same results. Twelve hospitalized patients were monitored in the CCU, after permanent PM implantation, for an average of 4 hours per patient. Although the PFA indicated 5% false-negative alarms for the hospitalized patients, it should be stressed that every true PM failure was promptly detected. It is anticipated that routine use of the PFA for management of paced patients will reduce the expenses incurred by frequent visits, as well as simplify the follow-up and surveillance of ambulatory and hospitalized patients, thereby facilitating the work of the medical staff. PMID:6160494

  15. Cellular Cardiomyoplasty and Cardiac Regeneration

    PubMed Central

    Pendyala, Lakshmana; Goodchild, Traci; Gadesam, Radhika R.; Chen, Jack; Robinson, Keith; Chronos, Nicolas; Hou, Dongming

    2008-01-01

    Despite of vast improvements in treatment, myocardial infarction often leads to heart failure (HF) which remains the leading cause of death in developed countries. Other than heart transplantation, therapeutic options have a limited role in improving out comes in patients with severe HF. It is therefore no surprise that cardiac cell therapy has raised many hopes as a novel therapeutic approach aimed at cardiac myocyte replacement/regeneration termed “cellular cardiomyoplasty”. However, the ideal source, cell type, critical cell number, and mode of application for optimal therapeutic effect have not been defined thus far. Recent observations of the beneficial effect of cell transplantation in animal experiments have generated tremendous excitement and stimulated clinical studies suggesting that this approach is feasible, safe, and potentially effective in humans. Cell-based myocardial regeneration is currently being explored for a wide range of cardiac disease states, including acute and chronic ischemic myocardial damage, cardiomyopathy and as biological heart pacemakers. The main purpose of this article is to review recent literature on the use of various cells for the examination of their in vitro cardiogenic potential and their in vivo capacity to engraft and improve the functional properties of the infarcted heart. PMID:19936280

  16. Exercise Programming for Cardiacs--A New Direction for Physical Therapists.

    ERIC Educational Resources Information Center

    Gutin, Bernard

    This speech begins with the presentation of a conceptual scheme of the physical working capacity of a person starting a training program. The scheme shows that after exercise, when recovery begins and sufficient time elapses, the individual recovers and adapts to a level of physical working capacity which is higher than his starting level. From…

  17. Flexibility and Strength Measures in Children Participating in a Cardiac Rehabilitation Exercise Program.

    ERIC Educational Resources Information Center

    Koch, Barbara M.; And Others

    1988-01-01

    A 12-week structured rehabilitation program featuring warm-up exercises, increased aerobic exercise, cool down, and home-based continuation of exercise helped 12 children with surgically corrected congenital heart disease improve lower extremity strength and flexibility. (Author/CB)

  18. Transcatheter aortic valve replacement: establishing a comprehensive program model for hybrid cardiac catheterization laboratories in the Department of Veterans Affairs.

    PubMed

    Speiser, Bernadette; Dutra-Brice, Cynthia

    2014-01-01

    Aortic valve disease, especially aortic stenosis, becomes progressively debilitating and carries a high mortality risk if it is categorized as severe and symptomatic (J Thorac Cardiovas Surg. 2012;144(3):e29-e84). In the past, the only treatment for aortic stenosis was surgical aortic valve replacement. Surgical treatment may require several hours of cardioplegia, and if the patient has comorbidities, such as renal failure or chronic obstructive pulmonary disease, their operative mortality percentage increases.In 2011, the US Food and Drug Administration approved the use of a transcatheter aortic valve replacement (TAVR) procedure for patients who were deemed high risk or inoperative for the routine surgical aortic valve replacement surgery. More than 20,?000 TAVRs have been performed in patients worldwide since 2002 when Dr Alain Cribier performed the first-in-man TAVR (Arch Cardiovasc Dis. 2012;105(3):145-152). The Edwards Lifesciences SAPIEN XT valve and the Medtronic CoreValve are commercially available.The clinical findings and economic statistic have supported the expansion of the TAVR procedure. However, there has been considerable controversy over where the procedure is to occur and who is directly responsible for directing the TAVR care. This debate has identified barriers to the implementation of a TAVR program. The operating rooms and a cardiac catheterization laboratory are underprepared for the hybrid valve replacement therapy. Because of the barriers identified, the Department of Veterans Affairs determined a need for a systematic approach to review the programs that applied for this structural heart disease program. A centralized team was developed to ensure room readiness and staff competency. The use of the Health Failure Mode and Effects Analysis can define high-risk clinical processes and conduct a hazard analysis. Worksheets can show potential failure modes and their probabilities, along with actions and outcome measures, team collaboration, extensive screening, and selection process. The TAVR program begins implementation with data entry with each case into CART-CL (Cardiovascular Assessment, Reporting and Tracking System for Cath Labs, Veteran Administration database for interventional cardiology procedures). If an untoward event occurs, within 24 hours the CART-CL Quality Assessment Team is activated to begin the review process. This provides real-time review and feedback to the local facility in an expeditious manner. Cardiac catheterization laboratories have been inundated with rapidly changing technological advances in the past decade. The era for structural heart repair is rapidly mobilizing from a surgical/operating room setting to a transcatheter/hybrid catheterization laboratory suite. The use of the new hybrid catheterization laboratories will continue to expand as the approval of future transcatheter therapies evolve. Editor's note: Due to the volume of important information presented in each table, only the first table is included in the print version of the article, however, all tables may be viewed in their entirety free of charge on the online version of this article: http://journals.lww.com/dccnjournal/pages/default.aspx. PMID:25144213

  19. Impact of the Training Program on Lipid Profile and Cardiac Health

    Microsoft Academic Search

    REGINA COELI BURNEIKO; YEDA SANT'ANA DINIZ; LUCIANE APARECIDA FAINE; CRISTIANO MACHADO GALHARDI; CARLOS ROBERTO PADOVANI; ETHEL LOURENZI B. NOVELLI; ANTONIO CARLOS CICOGNA

    2004-01-01

    The aim of this study was to investigate the effects of training programs on serum lipid profile and myocardial oxidative stress. Male Wistar rats (2 mo-old) were divided into three groups (n=8): sedentary (S), loadless trained (T) and trained-overload 2% body weight (TL). T and TL were trained through swimming for 9 weeks. T and TL rats had increased myocardial

  20. National Heart Attack Alert Program Position Paper: Chest Pain Centers and Programs for the Evaluation of Acute Cardiac Ischemia

    Microsoft Academic Search

    Robert J. Zalenski; Harry P. Selker; Christopher P. Cannon; Helke M. Farin; W. Brian Gibler; Robert J. Goldberg; Costas T. Lambrew; Joseph P. Ornato; Robert J. Rydman; Pamela Steele

    2000-01-01

    The National Heart Attack Alert Program (NHAAP), which is coordinated by the National Heart, Lung, and Blood Institute (NHLBI), promotes the early detection and optimal treatment of patients with acute myocardial infarction and other acute coronary ischemic syndromes. The NHAAP, having observed the development and growth of chest pain centers in emergency departments with special interest, created a task force

  1. Mechanisms of clock output in the Drosophila circadian pacemaker system.

    PubMed

    Taghert, Paul H; Shafer, Orie T

    2006-12-01

    Molecular oscillations that underlie the circadian clock are coupled to different output signals by which daily rhythms in downstream events are evoked and/or synchronized. Here the authors review the literature that describes circadian output mechanisms in Drosophila. They begin at the most proximal level, within oscillator cells themselves, by surveying studies of rhythmic gene expression within Drosophila heads. Next the authors describe the several neuron groups that compose the circadian pacemaker network underlying rhythmic locomotor activity, and they detail current models of how that network is organized and coordinated. The authors outline the body of evidence that describes a role for the neuropeptide pigment dispersing factor (PDF) as a circadian transmitter in the fly brain. Finally, in the context of PDF, they consider studies that address mechanisms of signaling from the circadian pacemaker network to downstream neurons and nonneuronal cells that directly control rhythmic outputs. PMID:17107935

  2. A Spatially-Ordered Pacemaker Observed in Squid Giant Axons

    NASA Astrophysics Data System (ADS)

    Matsumoto, Gen; Aihara, Kazuyuki; Utsunomiya, Toshio

    1982-03-01

    It was both theoretically and experimentally demonstrated that a spatially-ordered pacemaker generating action potentials at a constant rhythm was formed at a restricted region on the squid giant axon in the state of self-sustained oscillation of the action potentials. The dynamics of the Hodgkin-Huxley equations with one-dimensional diffusion were analysed to study the spatially-ordered pacemaker under the following conditions; (1) the rate constants of sodium activation and inactivation, and potassium activation changed with the effective calcium concentration in the external medium, according to Frankenhaeuser and Hodgkin (J. Physiol. 137 (1957) 218), and (2) the membrane potentials at both ends of the axon were fixed to be zero. These experiments and calculation show that the repetitive firing state is spatially well organized and integrated, and that it could be called as the dissipative structure of Glansdorff and Prigogine macroscopically

  3. Endovascular extraction techniques for pacemaker and ICD lead extraction

    PubMed Central

    Bracke, F.A.; Meijer, A.; van Gelder, B.

    2001-01-01

    In the last few years, comprehensive endovascular techniques have been developed to extract chronically implanted pacemaker and defibrillator leads. It is important that referring physician have knowledge of the advantages and limitations of the different techniques. In this paper we discuss the techniques and results of the currently used endovascular extraction techniques. ImagesFigure 1Figure 2Figure 3Figure 4Figure 5Figure 6Figure 7 PMID:25696690

  4. Teaching cardiac electrophysiology modeling to undergraduate students: laboratory exercises and GPU programming for the study of arrhythmias and spiral wave dynamics

    NSDL National Science Digital Library

    Ezio Bartocci (Stony Brook University)

    2011-12-01

    As part of a 3-wk intersession workshop funded by a National Science Foundation Expeditions in Computing award, 15 undergraduate students from the City University of New York collaborated on a study aimed at characterizing the voltage dynamics and arrhythmogenic behavior of cardiac cells for a broad range of physiologically relevant conditions using an in silico model. The primary goal of the workshop was to cultivate student interest in computational modeling and analysis of complex systems by introducing them through lectures and laboratory activities to current research in cardiac modeling and by engaging them in a hands-on research experience. Results from these simulations, as well as some of the background and methodology taught during the workshop, is presented in this article along with the programming code and the explanations of simulation results in an effort to allow other teachers and students to perform their own demonstrations, simulations, and studies.

  5. Haemophilus parainfluenzae bacteremia associated with a pacemaker wire localized by gallium scan

    SciTech Connect

    Rosenbaum, G.S.; Calubiran, O.; Cunha, B.A. (Winthrop-Univ. Hospital, Mineola, NY (USA))

    1990-05-01

    A young woman with a history of sick sinus syndrome and placement of a permanent pacemaker 6 months before admission had fever and Haemophilus parainfluenzae bacteremia. A gallium scan localized the infection to the site of the pacemaker wire. Echocardiograms were negative for any vegetations. The patient responded to cefotaxime and trimethoprim-sulfamethoxazole therapy. We believe that this is the first case of H. parainfluenzae bacteremia associated with a pacemaker wire and localized by gallium scan.

  6. Physiological effects of light on the human circadian pacemaker

    NASA Technical Reports Server (NTRS)

    Shanahan, T. L.; Czeisler, C. A.

    2000-01-01

    The physiology of the human circadian pacemaker and its influence and on the daily organization of sleep, endocrine and behavioral processes is an emerging interest in science and medicine. Understanding the development, organization and fundamental properties underlying the circadian timing system may provide insight for the application of circadian principles to the practice of clinical medicine, both diagnostically (interpretation of certain clinical tests are dependent on time of day) and therapeutically (certain pharmacological responses vary with the time of day). The light-dark cycle is the most powerful external influence acting upon the human circadian pacemaker. It has been shown that timed exposure to light can both synchronize and reset the phase of the circadian pacemaker in a predictable manner. The emergence of detectable circadian rhythmicity in the neonatal period is under investigation (as described elsewhere in this issue). Therefore, the pattern of light exposure provided in the neonatal intensive care setting has implications. One recent study identified differences in both amount of sleep time and weight gain in infants maintained in a neonatal intensive care environment that controlled the light-dark cycle. Unfortunately, neither circadian phase nor the time of day has been considered in most clinical investigations. Further studies with knowledge of principles characterizing the human circadian timing system, which governs a wide array of physiological processes, are required to integrate these findings with the practice of clinical medicine.

  7. The value of redundancy in chronic bipolar pacemaker electrode systems.

    PubMed

    Holmes, D R; Gersh, B J; Shub, C; Maloney, J D; Merideth, J

    1980-07-01

    Bipolar pacing systems, because of the presence of two intracardiac electrodes, provide lead redundancy. This allows conversion of bipolar to unipolar pacing or the reversal of lead polarity. During a 3-year period, this redundancy was utilized in 34 (13.7%) of 248 patients with chronic bipolar lead systems during follow-up pacemaker surgery. Of the 34 patients, elective pulse generator change was the most frequent indication for surgery (23 patients) and in this group redundancy was used most often to select the lead configuration with the highest R-wave amplitude and lowest stimulation threshold, or to solve the problem of weld defects of the connector pins or frayed insulation. The remaining 11 patients underwent surgery for pacemaker system malfunction and in this group redundancy was used to avoid the need for lead repositioning or placement of a new catheter system. Lead redundancy in those patients in whom bipolar pacing has been selected provides flexibility at the time of additional pacemaker surgery, and its use may obviate the need for a change in catheter system when stimulation thresholds are excessive, wire fraction is irreparable, or bipolar sensing signals are inadequate. PMID:6160536

  8. Isolating Neural Correlates of the Pacemaker for Food Anticipation

    PubMed Central

    Blum, Ian David; Waddington Lamont, Elaine; Rodrigues, Trevor; Abizaid, Alfonso

    2012-01-01

    Mice fed a single daily meal at intervals within the circadian range exhibit food anticipatory activity. Previous investigations strongly suggest that this behaviour is regulated by a circadian pacemaker entrained to the timing of fasting/refeeding. The neural correlate(s) of this pacemaker, the food entrainable oscillator (FEO), whether found in a neural network or a single locus, remain unknown. This study used a canonical property of circadian pacemakers, the ability to continue oscillating after removal of the entraining stimulus, to isolate activation within the neural correlates of food entrainable oscillator from all other mechanisms driving food anticipatory activity. It was hypothesized that continued anticipatory activation of central nuclei, after restricted feeding and a return to ad libitum feeding, would elucidate a neural representation of the signaling circuits responsible for the timekeeping component of the food entrainable oscillator. Animals were entrained to a temporally constrained meal then placed back on ad libitum feeding for several days until food anticipatory activity was abolished. Activation of nuclei throughout the brain was quantified using stereological analysis of c-FOS expressing cells and compared against both ad libitum fed and food entrained controls. Several hypothalamic and brainstem nuclei remained activated at the previous time of food anticipation, implicating them in the timekeeping mechanism necessary to track previous meal presentation. This study also provides a proof of concept for an experimental paradigm useful to further investigate the anatomical and molecular substrates of the FEO. PMID:22558352

  9. Mitigation of postischemic cardiac contractile dysfunction by CaMKII inhibition: effects on programmed necrotic and apoptotic cell death.

    PubMed

    Szobi, Adrian; Rajtik, Tomas; Carnicka, Slavka; Ravingerova, Tana; Adameova, Adriana

    2014-03-01

    While Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) has been suggested to be an important protein regulating heart function upon ischemia/reperfusion (I/R), the mechanisms responsible are not fully known. Furthermore, it is not known whether CaMKII activation can modulate necroptosis, a recently described form of programmed cell death. In order to investigate these issues, Langendroff-perfused rat hearts were subjected to global ischemia and reperfusion, and CaMKII inhibition was achieved by adding the CaMKII inhibitor KN-93 (0.5 ?mol/dm(3)) to the perfusion solution before the induction of ischemia. Immunoblotting was used to detect changes in expression of proteins modulating both necroptotic and apoptotic cell death. CaMKII inhibition normalized I/R induced increases in expression of necroptotic RIP1 and caspase-8 along with proteins of the intrinsic apoptotic pathway, namely cytochrome c and caspase-9. In addition, it increased the Bcl-2/Bax ratio and reduced caspase-3 and cleaved PARP1 content suggesting reduction of cell death. These changes coexisted with improvement of postischemic contractile function. On the other hand, there was no correlation between levels of pT287-CaMKII? and LVDP recovery after I/R. These results demonstrate for the first time that CaMKII inhibition may mitigate cardiac contractile dysfunction, at least partially, by limiting the contents of not only apoptotic, but also necroptotic proteins. Phosphorylation of CaMKII seems unlikely to determine the degree of postischemic recovery of contractile function. PMID:24347176

  10. Radiation therapy planning of a breast cancer patient with in situ pacemaker--challenges and lessons.

    PubMed

    Munshi, Anusheel; Wadasadawala, Tabassum; Sharma, Pramod Kumar; Sharma, Dayananda; Budrukkar, Ashwini; Jalali, Rakesh; Dinshaw, Ketayun A

    2008-01-01

    A postmenopausal lady with an in situ pacemaker developed a lump in the left breast and was diagnosed to have breast cancer. The patient underwent breast conservative surgery and was planned for post operative radiotherapy. The location of the tumor relative to the pacemaker provided a unique challenge in planning radiotherapy and the patient had an uneventful post radiotherapy course. A literature review revealed that modern generation pacemakers are very sensitive to radiation compared to their older counterparts. The present article makes suggestions towards reducing dose in radiotherapy planning in pacemaker patients. PMID:17943474

  11. Powering pacemakers from heartbeat vibrations using linear and nonlinear energy harvesters

    NASA Astrophysics Data System (ADS)

    Amin Karami, M.; Inman, Daniel J.

    2012-01-01

    Linear and nonlinear piezoelectric devices are introduced to continuously recharge the batteries of the pacemakers by converting the vibrations from the heartbeats to electrical energy. The power requirement of a pacemaker is very low. However, after few years, patients require another surgical operation just to replace their pacemaker battery. Linear low frequency and nonlinear mono-stable and bi-stable energy harvesters are designed according to the especial signature of heart vibrations. The proposed energy harvesters are robust to variation of heart rate and can meet the power requirement of pacemakers.

  12. Rescue of a Trafficking Defective Human Pacemaker Channel via a Novel Mechanism

    PubMed Central

    Lin, Yen-Chang; Huang, Jianying; Kan, Hong; Frisbee, Jefferson C.; Yu, Han-Gang

    2009-01-01

    Therapeutic strategies such as using channel blockers and reducing culture temperature have been used to rescue some long QT-associated voltage-gated potassium Kv trafficking defective mutant channels. A hyperpolarization-activated cyclic nucleotide-gated HCN4 pacemaker channel mutant (D553N) has been recently found in a patient associated with cardiac arrhythmias including long QT. D553N showed the defective trafficking to the cell surface, leading to little ionic current expression (loss-of-function). We show in this report that enhanced tyrosine phosphorylation mediated by Src, Fyn, and Yes kinases was able to restore the surface expression of D553N for normal current expression. Src or Yes, but not Fyn, significantly increased the current density and surface expression of D553N. Fyn accelerated the activation kinetics of the rescued D553N. Co-expression of D553N with Yes exhibited the slowest activation kinetics of D553N. Src, Fyn, and Yes significantly enhanced the tyrosine phosphorylation of D553N. A combination of Src, Fyn, and Yes rescued the current expression and the gating of D553N comparable with those of wild-type HCN4. In conclusion, we demonstrate a novel mechanism using three endogenous Src kinases to rescue a trafficking defective HCN4 mutant channel (D553N) by enhancing the tyrosine phosphorylation of the mutant channel protein. PMID:19748888

  13. Bleeding complications after pacemaker or cardioverter-defibrillator implantation in patients receiving dual antiplatelet therapy

    PubMed Central

    Przybylski, A.; Derejko, P.; Kwa?niewski, W.; Urba?czyk-?wi?, D.; Zakrzewska, J.; Orszulak, W.; Orczykowski, M.; Filipecki, A.; Szumowski, ?; Walczak, F.; Trusz-Gluza, M.

    2010-01-01

    Introduction. The aim of the study was to define the prevalence of bleeding events in patients treated with dual antiplatelet therapy (DAT) in comparison with patients receiving only acetylsalicylic acid (ASA). Methods. Prospective two-centre registry of all first implantations of pacemakers, cardioverter-defibrillators and cardiac resynchronisation therapy units in patients receiving ASA (n=194) or DAT (n=53). Results. Bleeding complications were detected in 27 (16.2%) patients in the ASA group and in 13 (24.5%) in the DAT group. There was no significant difference in the overall number of complications between the patients receiving ASA or DAT, although there was a trend towards a higher incidence of overall complication rates in the DAT group (p=0.0637). The incidence of major complications (requiring blood transfusion or surgical intervention or prolonging hospital stay) was low (3.6%), and similar in both groups (3.6 and 3.8% respectively, ns). The rate of minor complications (subcutaneous haematomas) was greater in the DAT group (p=0.015). Conclusions. Treatment with DAT does not increase the risk of major bleeding complications as a result of device implantation; however, minor complications are significantly more frequent. Our results suggest that DAT could be continued in patients undergoing device implantation with a moderate risk of bleeding complications. (Neth Heart J 2010;18:230–5.20505795) PMID:20505795

  14. [Newer treatment of epilepsy--brain pacemakers and transcranial magnetic stimulation].

    PubMed

    Akamatsu, Naoki

    2005-11-01

    The antiepileptic medication and surgical treatment had brought many patients with epilepsy to be seizure free, however, one third of the patients continue to experience seizures. There has recently been an explosion of research into brain stimulation for treating these intractable epilepsy patients. This is largely due to the success of deep brain stimulation of movement disorders. The intelligent cardiac pacemakers also stimulated the neurosurgeons to utilize the implantable devices. In this paper, brain stimulations with vagus nerve stimulator (VNS), depth electrodes, subdural electrodes, external responsive neuro-stimulator, implantable brain stimulator and transcranial magnetic stimulator are reviewed. The VNS had been approved in Europe and United States for clinical use. The efficacy of the VNS has already proven by the controlled trials. Stimulation of the thalamus, subthalamic nucleus and hippocampus showed some efficacy in a small number of patients, however, large scale traials remains to be undertaken. External responsive neurostimulator has shown efficacy and safety to justify further studies with implantable brain stimulators. The multi-center cooperative study is ongoing in the US to examine the usefulness of the implantable stimulator. Animal studies showed efficacy of the transcranial magnetic stimulation for the treatment and prevention of the seizures and status epilepticus. PMID:16447765

  15. "Subclinical" pacemaker syndrome: a randomised study of symptom free patients with ventricular demand (VVI) pacemakers upgraded to dual chamber devices.

    PubMed Central

    Sulke, N; Dritsas, A; Bostock, J; Wells, A; Morris, R; Sowton, E

    1992-01-01

    OBJECTIVE--To determine whether symptom free patients with single chamber pacemakers benefit from dual chamber pacing. DESIGN--A randomised double blind crossover comparison of ventricular demand (VVI), dual chamber demand (DDI), and dual chamber universal (DDD) modes after upgrading from a VVI device. SETTING--Cardiology outpatient department. PATIENTS--Sixteen patients aged 41-84 years who were symptom free during VVI mode pacing for three or more years. INTERVENTION--Pacemaker upgrade during routine generator change. MAIN OUTCOME MEASURES--Change in subjective (general health perception, symptoms) and objective (clinical assessment, treadmill exercise, and radiological and echocardiographic indices) results between pacing modes before and after upgrading. RESULTS--75% preferred DDD, 68% found VVI least acceptable with 12% expressing no preference. Perceived general well-being and exercise capacity (p less than 0.01) and treadmill times (p less than 0.05) were improved in DDD mode but VVI and DDI modes were similar. Clinical, echocardiographic, radiological, and electrophysiological indices confirmed the absence of overt pacemaker syndrome, although mitral and tricuspid regurgitation was greatest in VVI mode (p less than 0.01). CONCLUSIONS--Most patients who were satisfied with long term pacing in VVI mode benefited from upgrading to DDD mode pacing suggesting the existence of "subclinical" pacemaker syndrome in up to 75% of such patients. The DDI mode offered little subjective or objective benefit over VVI mode in this population and should be reserved for patients with paroxysmal atrial arrhythmias. VVI mode pacing should be used only for patients with very intermittent symptomatic bradycardia or atrial fibrillation with a good chronotropic response during exercise. PMID:1739528

  16. From syncitium to regulated pump: a cardiac muscle cellular update

    NSDL National Science Digital Library

    PhD Donna H. Korzick (Pennsylvania State University Dept. of Physiology and Kinesiology)

    2011-03-01

    The primary purpose of this article is to present a basic overview of some key teaching concepts that should be considered for inclusion in an six- to eight-lecture introductory block on the regulation of cardiac performance for graduate students. Within the context of cardiac excitation-contraction coupling, this review incorporates information on Ca2+ microdomains and local control theory, with particular emphasis on the role of Ca2+ sparks as a key regulatory component of ventricular myocyte contraction dynamics. Recent information pertaining to local Ca2+ cycling in sinoatrial nodal cells (SANCs) as a mechanism underlying cardiac automaticity is also presented as part of the recently described coupled-clock pacemaker system. The details of this regulation are emerging; however, the notion that the sequestration and release of Ca2+ from internal stores in SANCs (similar to that observed in ventricular myocytes) regulates the rhythmic excitation of the heart (i.e., membrane ion channels) is an important advancement in this area. The regulatory role of cardiac adrenergic receptors on cardiac rate and function is also included, and fundamental concepts related to intracellular signaling are discussed. An important point of emphasis is that whole organ cardiac dynamics can be traced back to cellular events regulating intracellular Ca2+ homeostasis and, as such, provides an important conceptual framework from which students can begin to think about whole organ physiology in health and disease. Greater synchrony of Ca2+-regulatory mechanisms between ventricular and pacemaker cells should enhance student comprehension of complex regulatory phenomenon in cardiac muscle.

  17. Optimizing the programation of cardiac resynchronization therapy devices in patients with heart failure and left bundle branch block.

    PubMed

    Vidal, Bàrbara; Sitges, Marta; Marigliano, Alba; Delgado, Victoria; Díaz-Infante, Ernesto; Azqueta, Manel; Tamborero, David; Tolosana, José María; Berruezo, Antonio; Pérez-Villa, Félix; Paré, Carles; Mont, Lluís; Brugada, Josep

    2007-09-15

    This study was conducted to investigate the clinical impact of cardiac resynchronization device optimization. A series of 100 consecutive patients received cardiac resynchronization therapy. In the first 49 patients, an empirical atrioventricular delay of 120 ms was set, with simultaneous biventricular stimulation (interventricular [VV] interval=0 ms). In the next 51 patients, systematic atrioventricular optimization was performed. VV optimization was also performed, selecting 1 VV delay: right or left ventricular preactivation (+30 or -30 ms) or simultaneous (VV interval=0 ms), according to the best synchrony obtained by tissue Doppler-derived wall displacement. At follow-up, patients who were alive without cardiac transplantation and showed improvement of >or=10% in the distance walked in the 6-minute walking test were considered responders. There were no differences between the 2 groups at baseline. Left ventricular ejection fraction improved in the 2 groups, but left ventricular cardiac output improved only in the optimized group. At 6 months, patients with optimized devices walked slightly further in the 6-minute walking test (497+/-167 vs 393+/-123 m, p<0.01), with no differences in New York Heart Association functional class or quality of life compared with nonoptimized patients. Overall, the number of nonresponders were similar in the 2 groups (27% vs 23%, p=NS). In conclusion, the echocardiographic optimization of cardiac resynchronization devices provided a slight incremental clinical benefit at midterm follow-up. Simple and rapid methods to routinely optimize the devices are warranted. PMID:17826387

  18. Sudden unexpected death in epilepsy: a series from an epilepsy surgery program and speculation on the relationship to sudden cardiac death.

    PubMed

    Dasheiff, R M

    1991-04-01

    Sudden unexpected death represents a significant cause of mortality in people with epilepsy. It derives this significance not because it is the most frequent cause of death but because it is apparently a direct consequence of a seizure. The implication is that epilepsy is an inherently lethal disorder. Seven patients who were studied in an epilepsy surgery program died a sudden unexpected death. This incidence of sudden unexpected death was five times higher than the 1-2/1,000 per year reported in the general epilepsy population. Sudden unexpected death shares some of the characteristics associated with sudden cardiac death, which kills 300,000 people in the United States each year. A cardiac arrhythmia, usually ventricular fibrillation, is the most common terminal event for sudden cardiac death and is the leading candidate as the mechanism for sudden unexpected death. Despite this knowledge, little is known on how to identify a high-risk group of patients for sudden death or how these deaths might be prevented. PMID:2050822

  19. Pacemaker extrusion in a severely demented patient. Device reimplantation via the femoral approach

    PubMed Central

    Pavlidis, Antonios N; Orfanidis, Zaharias; Giannakopoulos, Andreas; Poulimenos, Leonidas E; Kallistratos, Manolis S; Mpampageorgakas, Prodromos; Manolis, Athanasios J

    2011-01-01

    Extrusion of the generator is an infrequent complication following pacemaker implantation. Occlusion or stenosis of the deep venous system is common in elderly patients and can cause significant difficulties in transvenous pacing. The present study reports a rare case of pacemaker extrusion in an elderly patient with an inaccessible upper extremities deep venous system, requiring device reimplantation via the femoral route. PMID:21747659

  20. 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

    2015-06-01

    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. PMID:26041931

  1. Using the Virtual Heart Model to validate the mode-switch pacemaker operation

    Microsoft Academic Search

    Zhihao Jiang; Allison Connolly; Rahul Mangharam

    2010-01-01

    Artificial pacemakers are one of the most widely-used implantable devices today, with millions implanted worldwide. The main purpose of an artificial pacemaker is to treat bradycardia, or slow heart beats, by pacing the atrium and ventricles at a faster rate. While the basic functionality of the device is fairly simple, there are many documented cases of death and injury due

  2. Effect of 1. 5 tesla nuclear magnetic resonance imaging scanner on implanted permanent pacemakers

    Microsoft Academic Search

    David L. Hayes; David R. Holmes Jr.; Joel E. Gray

    1987-01-01

    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

  3. Cardiac Catheterization

    MedlinePLUS

    ... done during a cardiac catheterization include: closing small holes inside the heart repairing leaky or narrow heart ... bandage. It's normal for the site to be black and blue, red, or slightly swollen for a ...

  4. Cardiac Sarcoidosis

    MedlinePLUS

    ... do at National Jewish Health? We provide comprehensive cardiology evaluation and consultation and non-invasive cardiac testing. ... the whole person, not just the disease. Our cardiology team works with healthcare providers from all areas ...

  5. Nuclear cardiac

    SciTech Connect

    Slutsky, R.; Ashburn, W.L.

    1982-01-01

    The relationship between nuclear medicine and cardiology has continued to produce a surfeit of interesting, illuminating, and important reports involving the analysis of cardiac function, perfusion, and metabolism. To simplify the presentation, this review is broken down into three major subheadings: analysis of myocardial perfusion; imaging of the recent myocardial infarction; and the evaluation of myocardial function. There appears to be an increasingly important relationship between cardiology, particularly cardiac physiology, and nuclear imaging techniques. (KRM)

  6. Cellular mechanisms of circadian pacemaking: beyond transcriptional loops.

    PubMed

    O'Neill, John S; Maywood, Elizabeth S; Hastings, Michael H

    2013-01-01

    Circadian clocks drive the daily rhythms in our physiology and behaviour that adapt us to the 24-h solar and social worlds. Because they impinge upon every facet of metabolism, their acute or chronic disruption compromises performance (both physical and mental) and systemic health, respectively. Equally, the presence of such rhythms has significant implications for pharmacological dynamics and efficacy, because the fate of a drug and the state of its therapeutic target will vary as a function of time of day. Improved understanding of the cellular and molecular biology of circadian clocks therefore offers novel approaches for therapeutic development, for both clock-related and other conditions. At the cellular level, circadian clocks are pivoted around a transcriptional/post-translational delayed feedback loop (TTFL) in which the activation of Period and Cryptochrome genes is negatively regulated by their cognate protein products. Synchrony between these, literally countless, cellular clocks across the organism is maintained by the principal circadian pacemaker, the suprachiasmatic nucleus (SCN) of the hypothalamus. Notwithstanding the success of the TTFL model, a diverse range of experimental studies has shown that it is insufficient to account for all properties of cellular pacemaking. Most strikingly, circadian cycles of metabolic status can continue in human red blood cells, devoid of nuclei and thus incompetent to sustain a TTFL. Recent interest has therefore focused on the role of oscillatory cytosolic mechanisms as partners to the TTFL. In particular, cAMP- and Ca²?-dependent signalling are important components of the clock, whilst timekeeping activity is also sensitive to a series of highly conserved kinases and phosphatases. This has led to the view that the 'proto-clock' may have been a cytosolic, metabolic oscillation onto which evolution has bolted TTFLs to provide robustness and amplify circadian outputs in the form of rhythmic gene expression. This evolutionary ascent of the clock has culminated in the SCN, a true pacemaker to the innumerable clock cells distributed across the body. On the basis of findings from our own and other laboratories, we propose a model of the SCN pacemaker that synthesises the themes of TTFLs, intracellular signalling, metabolic flux and interneuronal coupling that can account for its unique circadian properties and pre-eminence. PMID:23604476

  7. Heart Rate Reduction by Ivabradine Reduces Diastolic Dysfunction and Cardiac Fibrosis

    Microsoft Academic Search

    David Busseuil; Yanfen Shi; Mélanie Mecteau; Geneviève Brand; Marc-Antoine Gillis; Eric Thorin; Caroline Asselin; Philippe Roméo; Tack Ki Leung; Jean-Gilles Latour; Christine Des Rosiers; Muriel Bouly; Eric Rhéaume; Jean-Claude Tardif

    2010-01-01

    Objectives: To determine if heart rate (HR) reduction with ivabradine (IVA), a selective inhibitor of the pacemaker If current, prevents cardiac dysfunction associated with dyslipidemia. Methods: New Zealand White rabbits received either a standard diet, a 0.5% cholesterol-enriched diet only (CD), or a 0.5% CD with IVA (17 mg\\/kg\\/day) for 12 weeks. HR, left ventricular (LV) systolic function, diastolic function

  8. A Model of Cardiac Electrical Activity Incorporating Ionic Pumps and Concentration Changes

    Microsoft Academic Search

    D. Difrancesco; D. Noble

    1985-01-01

    Equations have been developed to describe cardiac action potentials and pacemaker activity. The model takes account of extensive developments in experimental work since the formulation of the M.N.T. (R. E. McAllister, D. Noble and R. W. Tsien, J. Physiol., Lond. 251, 1-59 (1975)) and B.R. (G. W. Beeler and H. Reuter, J. Physiol., Lond. 268, 177-210 (1977)) equations. The current

  9. Cardiac resynchronization therapy in patients with absent right but persistent left superior vena cava.

    PubMed

    Kortner, A; Keyser, A; Schmid, C

    2009-06-01

    Abnormalities of the vena cava system are usually asymptomatic and are found incidentally during pacemaker implantation or catherization. We report a case of dilative cardiomyopathy requiring cardiac resynchronization defibrillator therapy (CRT-D). During the operation, a persistent left superior vena cava with an absent right vena cava was discovered. During open chest surgery, we implanted a CRT-D with epicardial patches and pacing leads, which is a simple technique for safe and reliable biventricular defibrillator therapy in these patients. PMID:19670119

  10. Computational Model of Electrically Coupled, Intrinsically Distinct Pacemaker Neurons

    PubMed Central

    Soto-Treviño, Cristina; Rabbah, Pascale; Marder, Eve; Nadim, Farzan

    2005-01-01

    Electrical coupling between neurons with similar properties is often studied. Nonetheless, the role of electrical coupling between neurons with widely different intrinsic properties also occurs, but is less well understood. Inspired by the pacemaker group of the crustacean pyloric network, we developed a multicompartment, conductance-based model of a small network of intrinsically distinct, electrically coupled neurons. In the pyloric network, a small intrinsically bursting neuron, through gap junctions, drives 2 larger, tonically spiking neurons to reliably burst in-phase with it. Each model neuron has 2 compartments, one responsible for spike generation and the other for producing a slow, large-amplitude oscillation. We illustrate how these compartments interact and determine the dynamics of the model neurons. Our model captures the dynamic oscillation range measured from the isolated and coupled biological neurons. At the network level, we explore the range of coupling strengths for which synchronous bursting oscillations are possible. The spatial segregation of ionic currents significantly enhances the ability of the 2 neurons to burst synchronously, and the oscillation range of the model pacemaker network depends not only on the strength of the electrical synapse but also on the identity of the neuron receiving inputs. We also compare the activity of the electrically coupled, distinct neurons with that of a network of coupled identical bursting neurons. For small to moderate coupling strengths, the network of identical elements, when receiving asymmetrical inputs, can have a smaller dynamic range of oscillation than that of its constituent neurons in isolation. PMID:15728775

  11. [Early and late complications of endocardial pacemaker wires (author's transl)].

    PubMed

    Bücking, J; Voss, H; Stein, J; Hahner, U

    1980-06-01

    Comparison of early and late complications of 769 endocardial pacemaker wires implanted in the period between 1969 and 1973 with 861 wires implanted between 1974 and 1978 revealed a decline of the complication rate from 17% to 7.6%. The dislocation rate could be lowered from 6.2% to 1.6%. Other early complications (exist and entrance block) were not effected (3.5% as compared with 3.2%). Late complications declined from 6.2% to 2.9%. Of these the number of intravascular wire breakages constitutes a high proportion. The main reason for this improvement is the use of a flexible Flange-tip lead. A variation of testing the positional stability of the wire is described.--The indications for pacemaker implantation shifted from 3rd degree AV-Block to the diagnoses "pathological bradycardia" and "hypersensitive carotis sinus". The comparatively low complication rate permits the application of new types of wires only in a few selected patients until a sufficient number of cases and an adequate follow-up period have been reached for clinical evaluation of these wires. PMID:7445644

  12. Pacemaker dynamics in the full Morris-Lecar model

    NASA Astrophysics Data System (ADS)

    González-Miranda, J. M.

    2014-09-01

    This article reports the finding of pacemaker dynamics in certain region of the parameter space of the three-dimensional version of the Morris-Lecar model for the voltage oscillations of a muscle cell. This means that the cell membrane potential displays sustained oscillations in the absence of an external electrical stimulation. The development of this dynamic behavior is shown to be tied to the strength of the leak current contained in the model. The approach followed is mostly based on the use of linear stability analysis and numerical continuation techniques. In this way it is shown that the oscillatory dynamics is associated to the existence of two Hopf bifurcations, one subcritical and other supercritical. Moreover, it is explained that in the region of parameter values most commonly studied for this model such pacemaker dynamics is not displayed because of the development of two fold bifurcations, with the increase of the strength of the leak current, whose interaction with the Hopf bifurcations destroys the oscillatory dynamics.

  13. Method to Detect Cardiac Abnormalities Based on Electrocardiography and Sinoatrial Pacemaker Model

    E-print Network

    Wu, Mingshen

    multiple sensors. The work derives for the first time the thresholds of poles and zeros to diagnose deadly of a patient. One of the proven ways to diagnose heart diseases is to use electrocardiogram (ECG) signals

  14. Cardiac Action and Pacemaker Potentials based on the Hodgkin-Huxley Equations

    Microsoft Academic Search

    D. Noble

    1960-01-01

    SINCE the equations describing the nerve action potential were formulated by Hodgkin and Huxley1, the range of phenomena to which they have been shown to apply has been greatly extended. Huxley2has applied them to the influence of temperature on the propagated response and to the repetitive firing observed in low calcium concentrations. More recently, Fitzhugh3 has shown that the long

  15. Pericarditis-Induced Hyponatremia after Cardiac Electronic Implantable Device (CEID) Procedures

    PubMed Central

    Rakhshan, Elnaz; Mirabbasi, Seyed Abbas; Khalighi, Bahar; Khalighi, Koroush

    2015-01-01

    Case series Patient: Female, 87 • Female, 83 Final Diagnosis: Hyponatremia induced by pericardial effusion Symptoms: Shortness of breath Medication: Colchicine Clinical Procedure: Cardiac Electronic Implantable Device (CEID) Specialty: Cardiology • Cardiac Electrophysiology Objective: Unusual clinical course Background: Pericardial effusion along with pleural effusion is one of the rare complications of permanent pacemaker placement. Although extremely uncommon, it is more prevalent in elderly patients and may be complicated with hyponatremia. Case Report: We observed development of hyponatremia in association with pericardial effusion and pleural effusion, within one month after pacemaker placement in two women with BMI of <20. Case 1: An 87-year-old woman underwent implantation of a transvenous AV sequential pacemaker because of severe bradycardia and complete heart block. Three weeks later, she complained of progressive left-sided rib cage pain and poor oral intake. Her echocardiography showed a moderately large amount of pericardial ef-fusion, but no evidence of tamponade. She also had hyponatremia (Na=119 mEq/dl). Extensive work-up suggested hyponatremia presumably due to SIADH, caused by pericardial/pleural effusion. Case 2: An 83-year-old woman with history of severe sick sinus syndrome required a transvenous Av sequential pacemaker 3 weeks before. She then presented with generalized weakness, fatigue, and poor oral intake of over one week. There was a small-moderate pericardial effusion echocardiographically, and her serum sodium was 116 mEq/dl. Conclusions: Although extremely uncommon, pericarditis can develop following transvenous pacemaker insertion, which may result in hyponatremia, likely due to SIADH. The most common scenario is an elderly, petite woman with low BMI (<20), usually after using a helical screw/active fixation pacing leads, several weeks post-implant. Early recognition and therapy can significantly improve outcome and morbidity. PMID:25913010

  16. Regional Difference in Dynamical Property of Sinoatrial Node Pacemaking: Role of Na+ Channel Current

    PubMed Central

    Kurata, Yasutaka; Matsuda, Hiroyuki; Hisatome, Ichiro; Shibamoto, Toshishige

    2008-01-01

    To elucidate the regional differences in sinoatrial node pacemaking mechanisms, we investigated 1), bifurcation structures during current blocks or hyperpolarization of the central and peripheral cells, 2), ionic bases of regional differences in bifurcation structures, and 3), the role of Na+ channel current (INa) in peripheral cell pacemaking. Bifurcation analyses were performed for mathematical models of the rabbit sinoatrial node central and peripheral cells; equilibrium points, periodic orbits, and their stability were determined as functions of parameters. Structural stability against applications of acetylcholine or electrotonic modulations of the atrium was also evaluated. Blocking L-type Ca2+ channel current (ICa,L) stabilized equilibrium points and abolished pacemaking in both the center and periphery. Critical acetylcholine concentration and gap junction conductance for pacemaker cessation were higher in the periphery than in the center, being dramatically reduced by blocking INa. Under hyperpolarized conditions, blocking INa, but not eliminating ICa,L, abolished peripheral cell pacemaking. These results suggest that 1), ICa,L is responsible for basal pacemaking in both the central and peripheral cells, 2), the peripheral cell is more robust in withstanding hyperpolarizing loads than the central cell, 3), INa improves the structural stability to hyperpolarizing loads, and 4), INa-dependent pacemaking is possible in hyperpolarized peripheral cells. PMID:18390617

  17. Glycinergic pacemaker neurons in preBötzinger complex of neonatal mouse.

    PubMed

    Morgado-Valle, Consuelo; Baca, Serapio M; Feldman, Jack L

    2010-03-10

    The preBötzinger complex (preBötC) is essential for normal respiratory rhythm generation in rodents, for which the underlying mechanisms remain unknown. Excitatory preBötC pacemaker neurons are proposed to be necessary for rhythm generation. Here we report the presence of a population of preBötC glycinergic pacemaker neurons. We used rhythmic in vitro transverse slice preparations from transgenic mice where neurons expressing the glycine transporter 2 (GlyT2) gene coexpress enhanced green fluorescent protein (EGFP). We combined epifluorescence and whole-cell patch-clamp recording to study preBötC EGFP-labeled, i.e., glycinergic, inspiratory-modulated neurons with pacemaker properties. We defined glycinergic pacemaker neurons as those preBötC EGFP neurons that exhibited the following: (1) ectopic bursting in rhythmic slices when depolarized during their normally silent period and (2) bursting when depolarized in nonrhythmic slices (following AMPA receptor blockade). Forty-two percent of EGFP-labeled neurons were inspiratory (n = 48 of 115), of which 23% (n = 11 of 48 inspiratory; 10% of the total recorded) were pacemakers. We conclude that there is a population of preBötC inspiratory-modulated glycinergic, presumably inhibitory, pacemaker neurons that constitute a substantial fraction of all preBötC pacemaker neurons. These findings challenge contemporary models for respiratory rhythmogenesis that assume the excitatory nature of preBötC pacemaker neurons. Testable and nontrivial predictions of the functional role of excitatory and inhibitory pacemaker neurons need to be proposed and the necessary experiments performed. PMID:20219997

  18. Cardiac amyloidosis.

    PubMed

    Kingman, A; Pereira, N L

    2001-05-01

    Cardiac amyloidosis should be considered in a patient with heart failure, who is normotensive with decreased left ventricular systolic function and marked left ventricular hypertrophy by echocardiogram and has decreased voltage by ECG. Furthermore, when the diagnosis of cardiac amyloid is made, it is important to classify the subtype of disease to be able to offer appropriate treatment. Contrary to traditional belief that the prognosis for patients with amyloidosis is dismal, some forms of this disease are curable and other forms are characterized by slow progression of disease. PMID:11381776

  19. Cardiac sarcoidosis

    PubMed Central

    Smedema, J.P.; Zondervan, P.E.; van Hagen, P.; ten Cate, F.J.; Bresser, P.; Doubell, A.F.; Pattynama, P.; Hoogsteden, H.C.; Balk, A.H.M.M.

    2002-01-01

    Sarcoidosis is a multi-system granulomatous disorder of unknown aetiology. Symptomatic cardiac involvement occurs in approximately 5% of patients. The prevalence of sarcoidosis in the Netherlands is unknown, but estimated to be approximately 20 per 100,000 population (3200 patients). We report on five patients who presented with different manifestations of cardiac sarcoidosis, and give a brief review on the current management of this condition. Magnetic Resonance Imaging (MRI) can be of great help in diagnosing this condition as well as in the follow-up of the response to therapy. ImagesFigure 1Figure 2Figure 3Figure 4Figure 5Figure 6 PMID:25696121

  20. Left Ventricular Synchrony and Function in Pediatric Patients with Definitive Pacemakers

    PubMed Central

    Ortega, Michel Cabrera; Morejón, Adel Eladio Gonzales; Ricardo, Giselle Serrano

    2013-01-01

    Background Chronic right ventricular pacing (RVP) induces a dyssynchronous contraction pattern, producing interventricular and intraventricular asynchrony. Many studies have shown the relationship of RVP with impaired left ventricular (LV) form and function. Objective The aim of this study was to evaluate LV synchrony and function in pediatric patients receiving RVP in comparison with those receiving LV pacing (LVP). Methods LV systolic and diastolic function and synchrony were evaluated in 80 pediatric patients with either nonsurgical or postsurgical complete atrioventricular block, with pacing from either the RV endocardium (n = 40) or the LV epicardium (n = 40). Echocardiographic data obtained before pacemaker implantation, immediately after it, and at the end of a mean follow-up of 6.8 years were analyzed. Results LV diastolic function did not change in any patient during follow-up. LV systolic function was preserved in patients with LVP. However, in children with RVP the shortening fraction and ejection fraction decreased from medians of 41% ± 2.6% and 70% ± 6.9% before implantation to 32% ± 4.2% and 64% ± 2.5% (p < 0.0001 and p < 0.0001), respectively, at final follow-up. Interventricular mechanical delay was significantly larger with RVP (66 ± 13 ms) than with LVP (20 ± 8 ms). Similarly, the following parameters were significantly different in the two groups: LV mechanical delay (RVP: 69 ± 6 ms, LVP: 30 ± 11 ms, p < 0.0001); septal to lateral wall motion delay (RVP: 75 ± 19 ms, LVP: 42 ± 10 ms, p < 0.0001); and, septal to posterior wall motion delay (RVP: 127 ± 33 ms, LVP: 58 ± 17 ms, p < 0.0001). Conclusion Compared with RV endocardium, LV epicardium is an optimal site for pacing to preserve cardiac synchrony and function. PMID:24061683

  1. Liénard-type models for the simulation of the action potential of cardiac nodal cells

    NASA Astrophysics Data System (ADS)

    Podziemski, P.; ?ebrowski, J. J.

    2013-10-01

    Existing models of cardiac cells which include multi-variable cardiac transmembrane current are too complex to simulate the long time dynamical properties of the heart rhythm. The large number of parameters that need to be defined and set for such models make them not only cumbersome to use but also require a large computing power. Consequently, the application of such models for the bedside analysis of heart rate of a specific patient may be difficult. Other ways of modelling need to be investigated. We consider the general problem of developing a model of cardiac pacemaker tissue that allows to combine the investigation of phenomena at a time scale of thousands of heart beats with the ability to reproduce realistic tissue-level characteristics of cell dynamics. We propose a modified van der Pol-Duffing equation-a Liénard-type oscillator-as a phenomenological model for cardiac nodal tissue, with certain important physiological similarities to ion-channel models of cardiac pacemaker cells. The model presented here is specifically designed to qualitatively reproduce mesoscopic characteristics of cell dynamics, including action potential duration (APD) restitution properties, phase response characteristics, and phase space structure. We show that these characteristics agree qualitatively with the extensive ionic models and experimental results in the literature [Anumonwo et al., 1991, [33], Cao et al., 1999, [49], Coster and Celler, 2003, [31], Qu, 2004, [45], Tsalikakis et al., 2007, [32], Inada et al., 2009, [14], Qu et al., 2010, [50

  2. SU-E-I-42: Normalized Embryo/fetus Doses for Fluoroscopically Guided Pacemaker Implantation Procedures Calculated Using a Monte Carlo Technique

    SciTech Connect

    Damilakis, J; Stratakis, J; Solomou, G [University of Crete, Heraklion (Greece)

    2014-06-01

    Purpose: It is well known that pacemaker implantation is sometimes needed in pregnant patients with symptomatic bradycardia. To our knowledge, there is no reported experience regarding radiation doses to the unborn child resulting from fluoroscopy during pacemaker implantation. The purpose of the current study was to develop a method for estimating embryo/fetus dose from fluoroscopically guided pacemaker implantation procedures performed on pregnant patients during all trimesters of gestation. Methods: The Monte Carlo N-Particle (MCNP) radiation transport code was employed in this study. Three mathematical anthropomorphic phantoms representing the average pregnant patient at the first, second and third trimesters of gestation were generated using Bodybuilder software (White Rock science, White Rock, NM). The normalized embryo/fetus dose from the posteroanterior (PA), the 30° left-anterior oblique (LAO) and the 30° right-anterior oblique (RAO) projections were calculated for a wide range of kVp (50–120 kVp) and total filtration values (2.5–9.0 mm Al). Results: The results consist of radiation doses normalized to a) entrance skin dose (ESD) and b) dose area product (DAP) so that the dose to the unborn child from any fluoroscopic technique and x-ray device used can be calculated. ESD normalized doses ranged from 0.008 (PA, first trimester) to 2.519 ?Gy/mGy (RAO, third trimester). DAP normalized doses ranged from 0.051 (PA, first trimester) to 12.852 ?Gy/Gycm2 (RAO, third trimester). Conclusion: Embryo/fetus doses from fluoroscopically guided pacemaker implantation procedures performed on pregnant patients during all stages of gestation can be estimated using the method developed in this study. This study was supported by the Greek Ministry of Education and Religious Affairs, General Secretariat for Research and Technology, Operational Program ‘Education and Lifelong Learning’, ARISTIA (Research project: CONCERT)

  3. False inhibition of an atrial demand pacemaker caused by an insulation defect in a polyurethane lead.

    PubMed

    van Gelder, L M; El Gamal, M I

    1983-09-01

    A patient who had an atrial demand pacemaker (AAI) presented with irregular pacing at a routine examination 5 months after implantation. When a magnet was applied over the pulse generator regular fixed rate pacing was obtained, thus proving oversensing in the system. Reprogramming the input sensitivity level to 2.5 and 5.0 mV did not solve the problem. Programming the pulse generator to the triggered mode (AAT) showed acceleration of the stimulation rate but also inhibition of the system. An S-S interval of 1260 ms was measured at a programmed interval of 857 ms (70 bpm). The pulse generator was disconnected and the intra-atrial electrogram was recorded. This showed different spurious signals varying in morphology and amplitude. Fortunately we were able to remove the lead (Medtronic 6991-U) from the atrial appendage. Subsequently a Helifix 12 mm AT lead was successfully implanted in the right atrial appendage and the same pulse generator was connected to the newly implanted lead. When the removed lead was examined by the manufacturer, a small tear in the insulation of the wire was detected. The dimensions of the tear were 0.1 X 0.7 mm. The tear was caused by stress corrosion cracking in the polyurethane tubing of the lead. PMID:6195601

  4. LVEDGE: A Knowledge-Based Heuristic Program For Border Finding Of The Left Ventricular Cavity In Cardiac Digital X-Ray Images

    NASA Astrophysics Data System (ADS)

    Fozzard, Richard; Gustafson, David

    1988-07-01

    Traditional edge-detection methods have involved grey-level thresholding and pixel neighborhood operations, as well as tracking algorithms. These purely mathematical aroaches have a tendency to generate many extra edges not relevant to the desired edge and are often fooled by artifacts such as catheters or rib boundaries. LVEDGE utilizes several techniques from artificial intelligence to deal with these difficulties. It has a user trainable knowledge-base to constrain the search to an expected left ventricular (LV) shape. A structure likelihood matrix is created based onprobabilities that pixels are on the actual edge. This matrix is then dynamically searched incorporating both local and global information to generate the most likely continuous single edge of the ventricle. The program has been run on digital LV images (some quite poor) and has compared favorably to human generated edges. The generated edges can be input to standard cardiac function analysis software (ejection fraction, regional wall motion, etc.)

  5. [Preoperative prophylactic pacemakers: apropos of their indication in a disputed case].

    PubMed

    Fuentes Rodríguez, R; Sebastianes Marfil, M C; Mato Ponce, M; Morales Guerrero, J; Torres Morera, L M

    2001-01-01

    The criteria for preoperative use of pacemakers are not unanimously agreed upon. Certain cases require careful assessment to weigh potential benefits against inherent risks in placing the device. Although external transcutaneous pacemakers, whose use circumvents the risks of transvenous insertion, have been available for years, such devices are not always appropriate, depending on the flow disorder involved or the type of surgery that will be performed. We report the case of a 75-year-old woman who was a candidate for surgery requiring general anesthesia (lumboperitoneal shunt due to chronic adult hydrocephaly). Although her condition did not initially call for prophylactic use of a pacemaker before surgery, changes soon developed that necessitated insertion of a temporary transvenous device for surgery and insertion of a permanent pacemaker the day after surgery. PMID:11234605

  6. Computational Modeling of the Regulation of Pacemaker Frequency in Dopamine Neurons Marco Huertas and Carmen Canavier

    E-print Network

    Ullmer, Brygg

    the electrical activity of dopamine neurons with spatially extended dendritic processes the native fast sodium conductance and replacing it with a virtual conductance using that the subthreshold component of the sodium current contributes to setting the pacemaking rate

  7. Torsade de pointes in a patient with complete atrioventricular block and pacemaker failure, misdiagnosed with epilepsy.

    PubMed

    Cai, Si-Yu; Ye, Shen-Feng; Wu, Xiang; Xiang, Mei-Xiang; Wang, Jian-An

    2015-01-01

    A case of torsade de pointes (TdP) with complete atrioventricular block and pacemaker failure that was misdiagnosed as epilepsy is presented herein. An 82-year-old female with recurrent seizure-like attacks showed epileptiform discharge during an electroencephalogram recording. A long QT interval and severe hypokalemia induced runs of TdP, which was related to pacemaker lead fracture, was detected during Holter recording and accompanied with episodes of seizures. After a DDD pacemaker with a new ventricular lead was replaced, there was no recurrence of any seizure-like attacks. Bradycardia-mediated TdP associated with complete atrioventricular block should not be missed in patients with recurrent seizure-like attacks even after pacemaker implantation. PMID:25771702

  8. Safety precautions in the management of patients with pacemakers when electrocautery operations are performed.

    PubMed

    Erdman, S; Levinsky, L; Servadio, C; Stoupel, E; Levy, M J

    1988-10-01

    The hazards related to ten patients who underwent 11 urologic surgical procedures during a 36 month period were taken into consideration. Electrocautery was used in all instances and there were no complications. All of the pacemakers were preset for ventricular pacing and sensing inhibited or multiprogrammable and were reprogrammed during the operation to ventricular pacing fixed rate mode or magnet mode, with very satisfactory outcome. To avoid life-threatening situations arising from pacemaker inhibition or ventricular fibrillation during cautery for transuretheral resection, three basic factors were considered: 1, appropriate type of pacemaker; 2, the proper grounding of all medical electronic equipment used during the procedure, and 3, the directing of the complete flow of the electrocautery circuits substantially below the level of the pacemaker unit. PMID:2458629

  9. 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

  10. Initial Experience of Implanted Pacemakers with Intracardiac Haemodynamic Sensor: Evaluation of Sensor Safety

    Microsoft Academic Search

    N. Galizio; J. Gonzalez; R. Chirife; H. Fraguas; J. Barra; S. Graf; E. Forteza; F. Gregorio

    In the present animal model study, TVI sensor operation did not interfere with conventional pacemaker functions of implanted\\u000a Sophós pacemakers. These results look promising since this sensor could play an important part in haemodynamic monitoring:\\u000a for physiological rate adaptation, for beat-tobeat capture confirmation, in patients with neurocardiogenic syncope, for the\\u000a follow-up of patients with heart failure, to indicate the best

  11. 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

  12. Simplified Interpretation of the Pacemaker Potential as a Tool For Teaching Membrane Potentials

    NSDL National Science Digital Library

    Sven Kurbel (Osijek Medical Faculty Department of Physiology)

    2003-09-01

    Most courses of physiology start by teaching about membrane potentials in different cells. Many of our students find these ideas difficult to understand. Often they try to memorize facts rather than understand mechanisms. The most difficult task may be interpretation of the pacemaker potential generation in sinoatrial (SA) cells. This illumination attempts to improve studentsÂ? understanding of membrane potentials by giving them a simplified interpretation of pacemaker potential generation before they have group discussions.

  13. Identification of the location of the colonic pacemakers: a histologic study.

    PubMed

    Shafik, Ahmed; El-Sibai, Olfat; Shafik, Ismail A; Shafik, Ali A

    2005-01-01

    A recent electrophysiologic study has suggested the existence of 4 pacemakers in the colon which generate the electric waves that are responsible for the colonic motor activity. These pacemakers are located at the cecal pole, the cecocolonic junction, the mid third of the transverse colon and at the colosigmoid junction. We investigated the hypothesis that these pacemaker sites contain ICCs in great numbers and that the electric waves generated from these sites are transmitted by a chain of ICCs to the remaining colon. Specimens were taken from the 4 electrophysiologically defined pacemaker sites and the remaining colon of 24 cadavers. They were subjected to c-kit immunohistochemistry tests. Controls for antisera specificity consisted of tissue incubation with normal rabbit serum substituted for the primary antiserum. The morphometric study was performed by submitting the immunohistochemically-stained sections to image analysis in order to determine the area percent of immuno-reactivity in comparison to the total area of fields examined in the sections. Data obtained from the image analyzer were statistically analyzed. Immunohistochemical and morphometric studies have shown that the 4 electrophysiologically defined pacemaker sites contained a significantly higher proportion of ICCs than the remaining colon, the ICCs at these sites being multipolar and forming a network surrounded by a fibrous tissue wall. In the remaining colon, the ICCs were bipolar and arranged in a linear fashion. The study revealed the existence of a network of ICCs at the 4 pacemaker sites forming the 'pacemaker nodes' (PMNs). In the rest of the colon, a chain of ICCs extended in the colonic wall in a linear fashion forming the 'pacemaker bundles' (PMBs). We postulate that the colonic electric waves start at the PMNs and spread in the colon along the PMBs. PMID:15769656

  14. Disseminated Mycobacterium chelonae infection causing pacemaker lead endocarditis in an immunocompetent host.

    PubMed

    Hooda, Amit; Pati, Purinder K; John, Bobby; George, Paul V; Michael, Joy Sarojini

    2014-01-01

    Pacemaker infection with Mycobacterium chelonae has not been reported previously. We report the first case of pacemaker lead endocarditis due to M. chelonae, which was successfully treated with multidrug regimen. M. chelonae is regarded as an environmental bacterium and its pathogenicity has been recognised recently. The present case illustrates its ability as a primary invader should not be underestimated, especially in an immunocompetent patient with indwelling devices. Epidemiology and management of this rare cause of culture-negative endocarditis is discussed. PMID:25535221

  15. Membrane resonance in bursting pacemaker neurons of an oscillatory network is correlated with network frequency

    PubMed Central

    Tohidi, Vahid; Nadim, Farzan

    2009-01-01

    Network oscillations typically span a limited range of frequency. In pacemaker-driven networks, including many Central Pattern Generators (CPGs), this frequency range is determined by the properties of bursting pacemaker neurons and their synaptic connections; thus, factors that affect the burst frequency of pacemaker neurons should play a role in determining the network frequency. We examine the role of membrane resonance of pacemaker neurons on the network frequency in the crab pyloric CPG. The pyloric oscillations (freq ~1 Hz) are generated by a group of pacemaker neurons: the Anterior Burster (AB) and the Pyloric Dilator (PD). We examine the impedance profiles of the AB and PD neurons in response to sinusoidal current injections with varying frequency and find that both neuron types exhibit membrane resonance, i.e. demonstrate maximal impedance at a given preferred frequency. The membrane resonance frequencies of the AB and PD neurons fall within the range of the pyloric network oscillation frequency. Experiments with pharmacological blockers and computational modeling show that both calcium currents ICa and the hyperpolarization-activated inward current Ih, are important in producing the membrane resonance in these neurons. We then demonstrate that both the membrane resonance frequency of the PD neuron and its supra-threshold bursting frequency can be shifted in the same direction by either DC current injection or by using the dynamic clamp technique to inject artificial conductances for Ih or ICa. Together, these results suggest that membrane resonance of pacemaker neurons can be strongly correlated with the CPG oscillation frequency. PMID:19458214

  16. Pacemaker rate and depolarization block in nigral dopamine neurons: a somatic sodium channel balancing act

    PubMed Central

    Tucker, Kristal R.; Huertas, Marco A.; Horn, John P.; Canavier, Carmen C.; Levitan, Edwin S.

    2012-01-01

    Midbrain dopamine (DA) neurons are slow intrinsic pacemakers that undergo depolarization (DP) block upon moderate stimulation. Understanding DP block is important because it has been correlated with the clinical efficacy of chronic antipsychotic drug treatment. Here we describe how voltage-gated sodium (NaV) channels regulate DP block and pacemaker activity in DA neurons of the substantia nigra using rat brain slices. The distribution, density and gating of NaV currents were manipulated by blocking native channels with tetrodotoxin and by creating virtual channels and anti-channels with dynamic clamp. Although action potentials initiate in the axon initial segment (AIS) and NaV channels are distributed in multiple dendrites, selective reduction of NaV channel activity in the soma was sufficient to decrease pacemaker frequency and increase susceptibility to DP block. Conversely, increasing somatic NaV current density raised pacemaker frequency and lowered susceptibility to DP block. Finally, when NaV currents were restricted to the soma, pacemaker activity occurred at abnormally high rates due to excessive local subthreshold NaV current. Together with computational simulations, these data show that both the slow pacemaker rate and the sensitivity to DP block that characterizes DA neurons result from the low density of somatic NaV channels. More generally, we conclude that the somatodendritic distribution of NaV channels is a major determinant of repetitive spiking frequency. PMID:23077037

  17. The East Asian Summer Monsoon in pacemaker experiments driven by ENSO

    NASA Astrophysics Data System (ADS)

    Ding, Hui; Greatbatch, Richard J.; Lu, Jian; Cash, Ben

    2015-03-01

    The variability of the East Asian summer monsoon (EASM) is studied using a pacemaker technique driven by ENSO in an atmospheric general circulation model (AGCM) coupled to a slab mixed layer model. In the pacemaker experiments, sea surface temperature (SST) is constrained to observations in the eastern equatorial Pacific through a q- flux that measures the contribution of ocean dynamics to SST variability, while the AGCM is coupled to the slab model. An ensemble of pacemaker experiments is analyzed using a multivariate EOF analysis to identify the two major modes of variability of the EASM. The results show that the pacemaker experiments simulate a substantial amount (around 45 %) of the variability of the first mode (the Pacific-Japan pattern) in ERA40 from 1979 to 1999. Different from previous work, the pacemaker experiments also simulate a large part (25 %) of the variability of the second mode, related to rainfall variability over northern China. Furthermore, we find that the lower (850 hPa) and the upper (200 hPa) tropospheric circulation of the first mode display the same degree of reproducibility whereas only the lower part of the second mode is reproducible. The basis for the success of the pacemaker experiments is the ability of the experiments to reproduce the observed relationship between El Niño Southern Oscillation (ENSO) and the EASM.

  18. Stochastic resonance on a modular neuronal network of small-world subnetworks with a subthreshold pacemaker.

    PubMed

    Yu, Haitao; Wang, Jiang; Liu, Chen; Deng, Bin; Wei, Xile

    2011-12-01

    We study the phenomenon of stochastic resonance on a modular neuronal network consisting of several small-world subnetworks with a subthreshold periodic pacemaker. Numerical results show that the correlation between the pacemaker frequency and the dynamical response of the network is resonantly dependent on the intensity of additive spatiotemporal noise. This effect of pacemaker-driven stochastic resonance of the system depends extensively on the local and the global network structure, such as the intra- and inter-coupling strengths, rewiring probability of individual small-world subnetwork, the number of links between different subnetworks, and the number of subnetworks. All these parameters play a key role in determining the ability of the network to enhance the noise-induced outreach of the localized subthreshold pacemaker, and only they bounded to a rather sharp interval of values warrant the emergence of the pronounced stochastic resonance phenomenon. Considering the rather important role of pacemakers in real-life, the presented results could have important implications for many biological processes that rely on an effective pacemaker for their proper functioning. PMID:22225376

  19. Cardiac Arrhythmias

    Microsoft Academic Search

    William J. Bonney; Ra-id Abdulla

    \\u000a An initial and crucial step in managing any child with a cardiac arrhythmia is to determine the hemodynamic stability of the\\u000a child. A healthy pink color of skin\\/mucosa, brisk capillary refill, good peripheral pulses, normal blood pressure, and absence\\u000a of respiratory distress are all reassuring signs that the hemodynamic status of the child is normal or near normal. Stable\\u000a hemodynamics

  20. Long-term clinical effects of ventricular pacing reduction with a changeover mode to minimize ventricular pacing in a general pacemaker population

    PubMed Central

    Stockburger, Martin; Boveda, Serge; Moreno, Javier; Da Costa, Antoine; Hatala, Robert; Brachmann, Johannes; Butter, Christian; Garcia Seara, Javier; Rolando, Mara; Defaye, Pascal

    2015-01-01

    Aim Right ventricular pacing (VP) has been hypothesized to increase the risk in heart failure (HF) and atrial fibrillation (AF). The ANSWER study evaluated, whether an AAI-DDD changeover mode to minimize VP (SafeR) improves outcome compared with DDD in a general dual-chamber pacemaker population. Methods and results ANSWER was a randomized controlled multicentre trial assessing SafeR vs. standard DDD in sinus node disease (SND) or AV block (AVB) patients. After a 1-month run-in period, they were randomized (1 : 1) and followed for 3 years. Pre-specified co-primary end-points were VP and the composite of hospitalization for HF, AF, or cardioversion. Pre-specified secondary end-points were cardiac death or HF hospitalizations and cardiovascular hospitalizations. ANSWER enrolled 650 patients (52.0% SND, 48% AVB) at 43 European centres and randomized in SafeR (n = 314) or DDD (n = 318). The SafeR mode showed a significant decrease in VP compared with DDD (11.5 vs. 93.6%, P < 0.0001 at 3 years). Deaths and syncope did not differ between randomization arms. No significant difference between groups [HR = 0.78; 95% CI (0.48–1.25); P = 0.30] was found in the time to event of the co-primary composite of hospitalization for HF, AF, or cardioversion, nor in the individual components. SafeR showed a 51% risk reduction (RR) in experiencing cardiac death or HF hospitalization [HR = 0.49; 95% CI (0.27–0.90); P = 0.02] and 30% RR in experiencing cardiovascular hospitalizations [HR = 0.70; 95% CI (0.49–1.00); P = 0.05]. Conclusion SafeR safely and significantly reduced VP in a general pacemaker population though had no effect on hospitalization for HF, AF, or cardioversion, when compared with DDD. PMID:25179761

  1. Capacity of dental equipment to interfere with cardiac implantable electrical devices.

    PubMed

    Lahor-Soler, Eduard; Miranda-Rius, Jaume; Brunet-Llobet, Lluís; Sabaté de la Cruz, Xavier

    2015-06-01

    Patients with cardiac implantable electrical devices should take precautions when exposed to electromagnetic fields. Possible interference as a result of proximity to electromagnets or electricity flow from electronic tools employed in clinical odontology remains controversial. The objective of this study was to examine in vitro the capacity of dental equipment to provoke electromagnetic interference in pacemakers and implantable cardioverter defibrillators. Six electronic dental instruments were tested on three implantable cardioverter defibrillators and three pacemakers from different manufacturers. A simulator model, submerged in physiological saline, with elements that reproduced life-size anatomic structures was used. The instruments were analyzed at differing distances and for different time periods of application. The dental instruments studied displayed significant differences in their capacity to trigger electromagnetic interference. Significant differences in the quantity of registered interference were observed with respect to the variables manufacturer, type of cardiac implant, and application distance but not with the variable time of application. The electronic dental equipment tested at a clinical application distance (20 cm) provoked only slight interference in the pacemakers and implantable cardioverter defibrillators employed, irrespective of manufacturer. PMID:25913780

  2. Circadian Pacemaking in Cells and Circuits of the Suprachiasmatic Nucleus

    PubMed Central

    Hastings, M H; Brancaccio, M; Maywood, E S

    2014-01-01

    The suprachiasmatic nucleus (SCN) of the hypothalamus is the principal circadian pacemaker of the brain. It co-ordinates the daily rhythms of sleep and wakefulness, as well as physiology and behaviour, that set the tempo to our lives. Disturbance of this daily pattern, most acutely with jet-lag but more insidiously with rotational shift-work, can have severely deleterious effects for mental function and long-term health. The present review considers recent developments in our understanding of the properties of the SCN that make it a robust circadian time-keeper. It first focuses on the intracellular transcriptional/ translational feedback loops (TTFL) that constitute the cellular clockwork of the SCN neurone. Daily timing by these loops pivots around the negative regulation of the Period (Per) and Cryptochrome (Cry) genes by their protein products. The period of the circadian cycle is set by the relative stability of Per and Cry proteins, and this can be controlled by both genetic and pharmacological interventions. It then considers the function of these feedback loops in the context of cytosolic signalling by cAMP and intracellular calcium ([Ca2+]i), which are both outputs from, and inputs to, the TTFL, as well as the critical role of vasoactive intestinal peptide (VIP) signalling in synchronising cellular clocks across the SCN. Synchronisation by VIP in the SCN is paracrine, operating over an unconventionally long time frame (i.e. 24 h) and wide spatial domain, mediated via the cytosolic pathways upstream of the TTFL. Finally, we show how intersectional pharmacogenetics can be used to control G-protein-coupled signalling in individual SCN neurones, and how manipulation of Gq/[Ca2+]i-signalling in VIP neurones can re-programme the circuit-level encoding of circadian time. Circadian pacemaking in the SCN therefore provides an unrivalled context in which to understand how a complex, adaptive behaviour can be organised by the dynamic activity of a relatively few gene products, operating in a clearly defined neuronal circuit, with both cell-autonomous and emergent, circuit-level properties. PMID:24329967

  3. Percutaneous coronary intervention delays pacemaker implantation in coronary artery disease patients with established bradyarrhythmias

    PubMed Central

    Zhong, Lihua; Gao, Yanhui; Xia, Hongyuan; Li, Xueqi; Wei, Shipeng

    2013-01-01

    BACKGROUND: Pacemakers have long been used to assist the heart under pathological conditions, and they are the first choice in the treatment of systematic bradyarrhythmias. However, the effect of percutaneous coronary intervention (PCI) in patients with coronary artery disease as well as bradyarrhythmias remains unknown. METHODS: In the present study, 42 patients with chest pain and/or abnormal stress test results were surveyed. Before coronary angiography, patients underwent complete examination, including a 24 h dynamic electrocardiogram, which was used to diagnose bradyarrhythmias that were not suitable for pacemaker implantation due to a lack of arrhythmia-related symptoms. All patients underwent PCI but did not undergo pacemaker implantation. Forty-one patients with chest pain and/or abnormal stress test results, as well as symptom-free bradyarrhythmias, were selected as the control group. All of the patients in the control group were committed to treatments without PCI. RESULTS: During a mean (±SD) of 3.3±0.5 years of follow-up (range 2.5 to 4.5 years), 24 of 42 patients who received PCI underwent pacemaker implantation for arrhythmia-related symptoms, eight were shown by Holter monitoring to have worsened but still exhibited no symptoms, and the remainder did not show any changes according to the examinations performed. In the control group, 31 patients underwent pacemaker implantation for arrhythmia-related symptoms, eight were shown by Holter monitoring to have worsened but still exhibited no symptoms, and two did not show any changes according to the examinations performed. Nevertheless, the rates of pacemaker implantation each year (from the first to the third year) between the two groups were 7.1% versus 39.0% (P=0.001); 33.3% versus 63.4% (P=0.006); and 57.1% versus 75.6%, (P=0.075), respectively. CONCLUSIONS: The present study found that PCI delayed the demand for pacemaker implantation among coronary artery disease patients. PMID:24294031

  4. Ectopic jejunal pacemakers and gastric emptying after Roux gastrectomy: Effect of intestinal pacing

    SciTech Connect

    Karlstrom, L.; Kelly, K.A. (Mayo Clinic, Rochester, MN (USA))

    1989-11-01

    The aims of this study were to determine whether ectopic pacemakers are present after meals in the Roux limbs of dogs after vagotomy and Roux gastrectomy, whether these pacemakers slow gastric emptying of liquids or solids, and whether abolishing the pacemakers with electric pacing might speed any slow emptying that occurs. In six dogs that underwent vagotomy and Roux gastrectomy and in four dogs that underwent vagotomy and Billroth gastrectomy (controls), myoelectric activity of the Roux limb or duodenum was measured during gastric emptying of a 500 kcal mixed meal of 99mTc-labeled cooked egg and 111In-labeled milk. Roux dogs were tested with and without pacing of the Roux limb. Roux dogs showed ectopic pacemaker in the Roux limb that drove the pacesetter potentials of the limb in a reverse, or orad, direction during 57% of the postprandial recordings. Billroth dogs had no ectopic pacemakers (p less than 0.05). Liquids emptied more slowly in Roux dogs (half-life (t1/2) = 121 +/- 15 minutes) than in Billroth dogs (t1/2 = 43 +/- 9 minutes; p less than 0.05), but solids emptied similarly in both groups of dogs (t1/2 approximately 8 hours). Pacing the Roux limb abolished the ectopic pacemakers, restored the slow emptying of liquids to the more rapid rate found in the Billroth dogs (t1/2: paced Roux, 72 +/- 15 minutes; Billroth, 43 +/- 9 minutes; p greater than 0.05) and did not change emptying of solids. The conclusion was that ectopic pacemakers present in the Roux limb after vagotomy and Roux gastrectomy drove the limb in a reverse direction and slowed emptying of liquids after the operation. The defect was corrected by pacing the Roux limb in a forward direction.

  5. Cardiac natriuretic peptides act via p38 MAPK to induce the brown fat thermogenic program in mouse and human adipocytes

    PubMed Central

    Bordicchia, Marica; Liu, Dianxin; Amri, Ez-Zoubir; Ailhaud, Gerard; Dessì-Fulgheri, Paolo; Zhang, Chaoying; Takahashi, Nobuyuki; Sarzani, Riccardo; Collins, Sheila

    2012-01-01

    The ability of mammals to resist body fat accumulation is linked to their ability to expand the number and activity of “brown adipocytes” within white fat depots. Activation of ?-adrenergic receptors (?-ARs) can induce a functional “brown-like” adipocyte phenotype. As cardiac natriuretic peptides (NPs) and ?-AR agonists are similarly potent at stimulating lipolysis in human adipocytes, we investigated whether NPs could induce human and mouse adipocytes to acquire brown adipocyte features, including a capacity for thermogenic energy expenditure mediated by uncoupling protein 1 (UCP1). In human adipocytes, atrial NP (ANP) and ventricular NP (BNP) activated PPAR? coactivator-1? (PGC-1?) and UCP1 expression, induced mitochondriogenesis, and increased uncoupled and total respiration. At low concentrations, ANP and ?-AR agonists additively enhanced expression of brown fat and mitochondrial markers in a p38 MAPK–dependent manner. Mice exposed to cold temperatures had increased levels of circulating NPs as well as higher expression of NP signaling receptor and lower expression of the NP clearance receptor (Nprc) in brown adipose tissue (BAT) and white adipose tissue (WAT). NPR-C–/– mice had markedly smaller WAT and BAT depots but higher expression of thermogenic genes such as Ucp1. Infusion of BNP into mice robustly increased Ucp1 and Pgc-1? expression in WAT and BAT, with corresponding elevation of respiration and energy expenditure. These results suggest that NPs promote “browning” of white adipocytes to increase energy expenditure, defining the heart as a central regulator of adipose tissue biology. PMID:22307324

  6. A mechanism for circadian control of pacemaker neuron excitability

    PubMed Central

    Ruben, Marc; Drapeau, Mark D.; Mizrak, Dogukan; Blau, Justin

    2014-01-01

    Although the intracellular molecular clocks that regulate circadian (~24 hr) behavioral rhythms are well-understood, it remains unclear how molecular clock information is transduced into rhythmic neuronal activity that in turn drives behavioral rhythms. To identify potential clock outputs, we generated expression profiles from a homogeneous population of purified pacemaker neurons (LNvs) from wild type and clock mutant Drosophila. We identified a group of genes with enriched expression in LNvs and a second group of genes rhythmically expressed in LNvs in a clock-dependent manner. Only 10 genes fell into both groups: four core clock genes including period and timeless, and six genes previously unstudied in circadian rhythms. We focused on one of these six genes, Ir, which encodes an Inward rectifier K+ channel likely to regulate resting membrane potential and whose expression peaks around dusk. Reducing Ir expression in LNvs increased larval light avoidance and lengthened the period of adult locomotor rhythms, consistent with increased LNv excitability. In contrast, increased Ir expression made adult flies largely arrhythmic and strongly dampened Period protein oscillations. We propose that rhythmic Ir expression contributes to daily rhythms in LNv neuronal activity, which in turn feed back to regulate molecular clock oscillations. PMID:23010658

  7. Effects of cardiac rehabilitation program on exercise capacity and chronotropic variables in patients with orthotopic heart transplant

    Microsoft Academic Search

    Hale Karapolat; Sibel Eyigor; Mehdi Zoghi; Tahir Yagdi; Sanem Nalbantgil; Berrin Durmaz; Mustafa Ozbaran

    2008-01-01

    Aim  To evaluate the effects of home- and hospital-exercise programs on exercise capacity and chronotropic variables in patients\\u000a with heart transplantation.\\u000a \\u000a \\u000a \\u000a Methods  Forty patients were randomized into two groups either hospital- or home-based exercise program. The patients were compared,\\u000a before and after the rehabilitation program, with respect to maximal oxygen uptake (pVO2), chronotropic variables [heart rate reserve (HRRe), heart rate recovery (HRR1),

  8. Improving outcomes for acute coronary syndrome patients in the hospital setting: successful implementation of the American Heart Association "Get With The Guidelines" program by Phase I cardiac rehabilitation nurses.

    PubMed

    Flynn, Frances M; Cafarelli, Mary; Petrakos, Karen; Christophersen, Patricia

    2007-01-01

    A treatment gap exists between published guidelines for secondary prevention of cardiovascular disease and application of these guidelines in clinical practice. The "Get With The Guidelines" program is a quality initiative developed by the American Heart Association to help acute care providers bridge this gap, thereby decreasing morbidity and mortality from cardiovascular disease. This article describes how cardiac rehabilitation nurses successfully implemented the program using a prospective case-management model in the acute care setting. An overview of the program including purpose, benefits, tools, and resources is provided along with start-up considerations, potential barriers, training needs, and keys to success. PMID:17545819

  9. An off-the-shelf plasma-based material to prevent pacemaker pocket infection.

    PubMed

    Schwartzman, David; Pasculle, A William; Ceceris, Kyra D; Smith, Jason D; Weiss, Lee E; Campbell, Phil G

    2015-08-01

    Bacterial infection of subcutaneous "pockets" housing cardiovascular implantable electronic devices is a significant clinical complication. In this study, pacemakers encapsulated in a blood plasma-based material (PBM) composited with antibiotics were investigated for use as prophylactics against such infections. PBMs, which are made from pooled allogeneic plasma and platelets, are off-the-shelf biomaterials that can be manufactured in the form of complex 3D shapes, extrudable putties, or injectable pastes. In vitro studies with PBM pastes formulated with rifampicin and minocycline demonstrated antibiotic release over 6 days, activity against Escherichia coli, and reduced cytotoxic effects of the antibiotics on fibroblasts. The materials were also evaluated in vivo in a rabbit model in which pacemaker pockets were inoculated with methicillin-resistant Staphylococcus aureus (S. aureus) strain and examined 1 week later. The pockets containing the pacemaker plus S. aureus were grossly purulent and culture positive, whereas pockets into which PBM with antibiotics were injected around the pacemaker were free of purulence and culture negative (p < 0.001). None of the pockets into which PBM without antibiotics were placed demonstrated purulence, but 60% were culture positive. These results demonstrate the potential of PBMs to deliver antibiotics to diminish the incidence of pocket infections for pacemakers and other implantable devices. PMID:25965281

  10. Starting and Stopping a Bistable Pacemaker: Stochastic Stimulation Identifies Critical Perturbations

    NASA Astrophysics Data System (ADS)

    Paydarfar, David; Forger, Daniel B.; Clay, John R.

    2005-08-01

    Bistable pacemakers exhibit highly nonlinear properties, such as abrupt transitions between repetitive firing and quiescence in response to small perturbing stimuli. We describe a search method for estimating optimum stimulus shapes and intensities for starting or stopping the repetitive firing of a bistable pacemaker. A large library of randomly generated stimuli is used to perturb the pacemaker, and a library of responses is recorded. From these two libraries, a rank order of desirability of the stimulus is generated to arrive at an estimate of the optimum stimulus shape. The search method was validated by calculus of variations applied to the Bonhoeffer-van der Pol (Fitzhugh-Nagumo) model of a bistable pacemaker. We found that the optimum stimulus for inducing a switch from one stable attractor to the other is a critically timed oscillatory stimulus. While the optimum stimulus shape for stopping the oscillator is similar to that for starting the oscillator, they differ in that stopping the oscillator requires that the stimulus is in antiphase to the natural rhythm, while the optimum stimulus for starting the oscillator is in phase with the natural rhythm. These theoretical predictions can be tested in real biological pacemakers, such as a recently described squid giant axon preparation that exhibits membrane bistability. Elucidation of optimum stimulus shapes may be useful for studying many periodic phenomena in biology and medicine. Our findings also suggest a novel approach to understanding how bistable membranes encode information over long time scales using fast noisy transients.

  11. Reexposure to nicotine during withdrawal increases the pacemaking activity of cholinergic habenular neurons

    PubMed Central

    Görlich, Andreas; Antolin-Fontes, Beatriz; Ables, Jessica L.; Frahm, Silke; ?limak, Marta A.; Dougherty, Joseph D.; Ibañez-Tallon, Inés

    2013-01-01

    The discovery of genetic variants in the cholinergic receptor nicotinic CHRNA5-CHRNA3-CHRNB4 gene cluster associated with heavy smoking and higher relapse risk has led to the identification of the midbrain habenula–interpeduncular axis as a critical relay circuit in the control of nicotine dependence. Although clear roles for ?3, ?4, and ?5 receptors in nicotine aversion and withdrawal have been established, the cellular and molecular mechanisms that participate in signaling nicotine use and contribute to relapse have not been identified. Here, using translating ribosome affinity purification (TRAP) profiling, electrophysiology, and behavior, we demonstrate that cholinergic neurons, but not peptidergic neurons, of the medial habenula (MHb) display spontaneous tonic firing of 2–10 Hz generated by hyperpolarization-activated cyclic nucleotide-gated (HCN) pacemaker channels and that infusion of the HCN pacemaker antagonist ZD7288 in the habenula precipitates somatic and affective signs of withdrawal. Further, we show that a strong, ?3?4-dependent increase in firing frequency is observed in these pacemaker neurons upon acute exposure to nicotine. No change in the basal or nicotine-induced firing was observed in cholinergic MHb neurons from mice chronically treated with nicotine. We observe, however, that, during withdrawal, reexposure to nicotine doubles the frequency of pacemaking activity in these neurons. These findings demonstrate that the pacemaking mechanism of cholinergic MHb neurons controls withdrawal, suggesting that the heightened nicotine sensitivity of these neurons during withdrawal may contribute to smoking relapse. PMID:24082085

  12. Cardiac aquaporins.

    PubMed

    Rutkovskiy, Arkady; Valen, Guro; Vaage, Jarle

    2013-11-01

    Aquaporins are a group of proteins with high-selective permeability for water. A subgroup called aquaglyceroporins is also permeable to glycerol, urea and a few other solutes. Aquaporin function has mainly been studied in the brain, kidney, glands and skeletal muscle, while the information about aquaporins in the heart is still scarce. The current review explores the recent advances in this field, bringing aquaporins into focus in the context of myocardial ischemia, reperfusion, and blood osmolarity disturbances. Since the amount of data on aquaporins in the heart is still limited, examples and comparisons from better-studied areas of aquaporin biology have been used. The human heart expresses aquaporin-1, -3, -4 and -7 at the protein level. The potential roles of aquaporins in the heart are discussed, and some general phenomena that the myocardial aquaporins share with aquaporins in other organs are elaborated. Cardiac aquaporin-1 is mostly distributed in the microvasculature. Its main role is transcellular water flux across the endothelial membranes. Aquaporin-4 is expressed in myocytes, both in cardiac and in skeletal muscle. In addition to water flux, its function is connected to the calcium signaling machinery. It may play a role in ischemia-reperfusion injury. Aquaglyceroporins, especially aquaporin-7, may serve as a novel pathway for nutrient delivery into the heart. They also mediate toxicity of various poisons. Aquaporins cannot influence permeability by gating, therefore, their function is regulated by changes of expression-on the levels of transcription, translation (by microRNAs), post-translational modification, membrane trafficking, ubiquitination and subsequent degradation. Studies using mice genetically deficient for aquaporins have shown rather modest changes in the heart. However, they might still prove to be attractive targets for therapy directed to reduce myocardial edema and injury caused by ischemia and reperfusion. PMID:24158693

  13. Restoration of cardio-circulatory regulation by rate-adaptive pacemaker systems: the bioengineering view of a clinical problem

    Microsoft Academic Search

    J. Werner; M. Hexamer; M. Meine; B. Lemke

    1999-01-01

    In the past, the development of rate-adaptive (sensor-controlled) pacemaker systems seems to have been determined primarily by the availability, compatibility and other properties of the technical sensor. This paper, however, focuses on the system physiological aspect in an attempt to answer the question to what extent physiological cardiovascular control is restored by the pacemaker system. This is a question which

  14. 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

  15. Permanent Pacemaker-Induced Superior Vena Cava Syndrome: Successful Treatment by Endovascular Stent

    SciTech Connect

    Lanciego, Carlos [Hospital Virgen de la Salud, Hospital Virgen del Valle, Complejo Hospitalario de Toledo, Toledo, Unit of Interventional Radiology (Spain)], E-mail: clanciego@eresmas.com; Rodriguez, Mario [Hospital Virgen de la Salud, Hospital Virgen del Valle, Complejo Hospitalario de Toledo, Toledo, Unit of Intensive Care (Spain); Rodriguez, Adela; Carbonell, Miguel A. [Hospital Virgen de la Salud, Hospital Virgen del Valle, Complejo Hospitalario de Toledo, Toledo, Unit of Geriatrics (Spain); Garcia, Lorenzo Garcia [Hospital Virgen de la Salud, Hospital Virgen del Valle, Complejo Hospitalario de Toledo, Toledo, Unit of Interventional Radiology (Spain)

    2003-11-15

    The use of metallic stents in the management of benign and malignant superior vena cava syndrome (SVCS) is well documented. Symptomatic stenosis or occlusion of the SVC is a rare complication of a transvenous permanent pacemaker implant. Suggested treatments have included anticoagulation therapy, thrombolysis, balloon angioplasty and surgery. More recently, endovascular stenting has evolved as an attractive alternative but the data available in the literature are limited. We describe a case in which venous stenting with a Wallstent endoprosthesis was used successfully. The patient remains symptom free and with normal pacemaker function 36 months later.

  16. Properties of pacemaker potentials recorded from myenteric interstitial cells of Cajal distributed in the mouse small intestine

    PubMed Central

    Kito, Yoshihiko; Suzuki, Hikaru

    2003-01-01

    Recording of electrical responses from isolated small intestine of mice using conventional microelectrodes revealed two types of potential, a pacemaker potential and a slow wave, both with rapid rising primary components and following plateau components. The rate of rise and peak amplitude were greater for pacemaker potentials than for slow waves, and the plateau component was smaller in slow waves than in pacemaker potentials. Both potentials oscillated at a similar frequency (20–30 min?1). Unitary potentials often discharged during the interval between pacemaker potentials. Infusion of Lucifer Yellow allowed visualization of the recorded cells; pacemaker potentials were recorded from myenteric interstitial cells of Cajal (ICC-MY) while slow waves were recorded from circular smooth muscle cells. Pacemaker potentials were characterized as follows: the primary component was inhibited by Ni2+, Ca2+-free solution or depolarization with high-K+ solution, the plateau component was inhibited by 4,4?-diisothiocyanostilbene-2,2?-disulphonic acid (DIDS), an inhibitor of Ca2+-activated Cl? channels, low [Cl?]o solution or Ca2+-free solution, and the generation of potentials was abolished by co-application of Ni2+and DIDS or by chelating intracellular Ca2+ with 1,2-bis(2-aminophenoxy)ethane-N,N,N’,N’-tetraacetic acid acetoxymethyl ester (BAPTA-AM). These results indicate that in the mouse small intestine ICC-MY generate pacemaker potentials with two components in situ; the primary and plateau components may be generated by activation of voltage-dependent Ca2+-permeable channels and Ca2+-activated Cl? channels, respectively. Slow waves are generated in circular smooth muscles via electrotonic spread of pacemaker potentials. These properties of intestinal pacemaker potentials are considered essentially similar to those of gastric pacemaker potentials. PMID:14565995

  17. "Caged Calcium" in Aplysia Pacemaker Neurons Characterization of Calcium-activated Potassium and

    E-print Network

    Zucker, Robert S.

    "Caged Calcium" in Aplysia Pacemaker Neurons Characterization of Calcium-activated Potassium-Anatomy, Universityof California, Berkeley, California 94720 ABSTRACT We have studied calcium-activated potassium neurons, using photolysis of a calcium chelator (nitr-5 or nitr-7) to release "caged calcium

  18. Millimeter waves thermally alter the firing rate of the Lymnaea pacemaker neuron

    Microsoft Academic Search

    S. I. Alekseev; N. V. Kochetkova; M. C. Ziskin; M. A. Bolshakov

    1997-01-01

    The effects of millimeter waves (mm-waves, 75 GHz) and temperature elevation on the firing rate of the BP-4 pacemaker neuron of the pond snail Lymnaea stagnalis were studied by using microelectrode techniques. The open end of a rectangular waveguide covered with a thin Teflon film served as a radiator. Specific absorption rates (SARs), measured in physiological solution at the radiator

  19. Initial experience in the extraction of chronically implanted pacemaker leads using the Excimer laser sheath

    PubMed Central

    Levy, T; Walker, S; Paul, V

    1999-01-01

    OBJECTIVE—To assess the safety and efficiency of the Excimer laser sheath in extracting chronically implanted pacemaker leads.?PATIENTS—Eight patients were studied (one female, mean age 62 years, range 34 to 77) with 17 pacemaker leads (five atrial, 10 ventricular, two implantable defibrillator). The mean implantation time was 65 months (range 23 to 188). The indications for lead extraction were chronic infection (7), superior vena cava obstruction (4), lead malfunction (4), and pain (2).?METHODS—A prospective analysis of the use of the Excimer laser sheath in extracting chronically implanted pacemaker leads. Laser sheath extraction was undertaken if conventional extraction techniques with simple traction or traction with a locking stylet had failed. If laser sheath extraction was unsuccessful, basket retrieval of the lead from the groin was performed.?RESULTS—Complete lead removal was achieved in 16 leads (94%). In one case the electrode tip was left behind without complication. Extraction was achieved with the laser sheath alone in 16 leads. Basket retrieval was required in one case after laser failure. There were no complications.?CONCLUSIONS—The Excimer laser sheath appears to be an effective and safe technique for extracting chronically implanted pacemaker leads. It can be used in combination with the currently available techniques for successful lead extraction.???Keywords: Excimer laser sheath; lead extraction; pacing PMID:10377320

  20. CaV3.1 is a tremor rhythm pacemaker in the inferior olive

    E-print Network

    Kim, Daesoo

    CaV3.1 is a tremor rhythm pacemaker in the inferior olive Young-Gyun Parka,1 , Hye-Yeon Parka,1 , C+ channels in the inferior olive contributes to the onset of the tremor in a pharmacological model that the CaV3.1-deficient inferior olive neurons lacked the subthreshold os- cillation of membrane potentials

  1. Diagnostic Dilemma: A Pacemaker Lead Inside the Left Atrium or an Echocardiographic Beam Width Artifact?

    Microsoft Academic Search

    Nikolaos Skubas; Natalia Ivascu Brown; Rakesh Mishra

    2006-01-01

    71-yr-old man with a permanent dual chamber pacemaker (pm), chronic atrial fibrillation with a slow ventricular response and symptomatic mi- tral regurgitation presented for mitral valve surgery. His intraoperative monitoring included, among oth- ers, a pulmonary artery catheter (PAC) and trans- esophageal echocardiography. The surgical approach was from the right atrium via an atrial septotomy, and the mitral valve was

  2. Activation of three types of membrane currents by various divalent cations in identified molluscan pacemaker neurons

    Microsoft Academic Search

    T. H. Muller; D. SWANDULLA; H. D. Lux

    1989-01-01

    We investigated membrane currents activated by intracellular diva- lent cations in two types of molluscan pacemaker neurons. A fast and quantitative pressure injection technique was used to apply Ca ~+ and other divalent cations. Ca 2§ was most effective in activating a nonspecific cation current and two types of K § currents found in these cells. One type of outward

  3. 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, individuals…

  4. Recurrent pericardial effusion caused by pacemaker lead perforation and warfarin therapy at seven years after implantation.

    PubMed

    Nakanishi, Hiroyuki; Kashiwase, Kazunori; Nishio, Mayu; Wada, Mitsuru; Hirata, Akio; Ueda, Yasunori

    2012-02-01

    A 66-year-old man was implanted with a pacemaker. Seven years after implantation he was admitted due to cardiogenic cerebral embolism and warfarin therapy was introduced. After that, he suffered recurrent pericardial effusion for unexplained reasons. An exploratory thoracotomy revealed that the screw of the atrial lead had penetrated through the right auricular appendage wall. PMID:22266846

  5. Successful Implantation of a Permanent Pacemaker through a Persistent Left Superior Vena cava

    Microsoft Academic Search

    Ali H. Al-Sayegh; Fawziah Al-Kandari

    2002-01-01

    We present a case of successful implantation of a permanent pacemaker through an unusual course of a persistent left superior vena cava (PLSVC). A young male patient presented with symptomatic bradycardia and a heart rate of 35 beats per minute. The pacing lead was introduced through the standard left subclavian vein approach and was found to pass through an unusual

  6. W\\/kit gene required for interstitial cells of Cajal and for intestinal pacemaker activity

    Microsoft Academic Search

    Jan D. Hulzinga; Lars Thuneberg; Michael Klüppel; John Malysz; Hanne B. Mikkelsen; Alan Bernstein

    1995-01-01

    THE pacemaker activity in the mammalian gut is responsible for generating anally propagating phasic contractions. The cellular basis for this intrinsic activity is unknown. The smooth muscle cells of the external muscle layers and the innervated cellular network of interstitial cells of Cajal, which is closely associated with the external muscle layers of the mammalian gut, have both been proposed

  7. 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 ?V; 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

  8. Shengmaisan Regulates Pacemaker Potentials in Interstitial Cells of Cajal in Mice

    PubMed Central

    Kim, Byung Joo

    2013-01-01

    Objectives: Shengmaisan (SMS) is a traditional Chinese medicine prescription widely used for the treatment of diverse organs in Korea. The interstitial cells of Cajal (ICCs) are pacemaker cells that play an important role in the generation of coordinated gastrointestinal (GI) motility. We have aimed to investigate the effects of SMS in the ICCs in the mouse small intestine. Methods: To dissociate the ICCs, we used enzymatic digestions from the small intestine in a mouse. After that, the ICCs were identified immunologically by using the anti-c-kit antibody. In the ICCs, the electrophysiological whole-cell patch-clamp configuration was used to record pacemaker potentials in the cultured ICCs. Results: The ICCs generated pacemaker potentials in the mouse small intestine. SMS produced membrane depolarization with concentration-dependent manners in the current clamp mode. Pretreatment with a Ca2+ free solution and thapsigargin, a Ca2+-ATPase inhibitor in the endoplasmic reticulum, stopped the generation of the pacemaker potentials. In the case of Ca2+-free solutions, SMS induced membrane depolarizations. However, when thapsigargin in a bath solution was applied, the membrane depolarization was not produced by SMS. The membrane depolarizations produced by SMS were inhibited by U-73122, an active phospholipase C (PLC) inhibitors. Furthermore, chelerythrine and calphostin C, a protein kinase C (PKC) inhibitors had no effects on SMS-induced membrane depolarizations. Conclusions: These results suggest that SMS might affect GI motility by modulating the pacemaker activity through an internal Ca2+- and PLC-dependent and PKC-independent pathway in the ICCs. PMID:25780681

  9. Cardiac Operations for North American Children with Rheumatic Diseases: 1985–2005

    PubMed Central

    Stingl, Cory; Moller, James H.

    2010-01-01

    Certain pediatric rheumatic diseases are known to affect the heart, sometimes requiring surgical intervention. The Pediatric Cardiac Care Consortium database was used to characterize cardiac surgical intervention among children with rheumatic diseases from 1985 to 2005. From this large database, the records for patients younger than 21 years who underwent cardiac surgery for any rheumatic disorder were extracted. The data collected included the type of procedure performed, the age at the time of the procedure, and the year the procedure was performed. The 261 pediatric patients identified underwent 361 cardiac surgical procedures for complications of rheumatic heart disease (RHD; 160 patients), neonatal lupus (NLE; 53 patients), Kawasaki disease (KD; 28 patients), systemic lupus erythematosus (SLE; 13 patients), and juvenile rheumatoid arthritis (JRA; 7 patients). Multiple procedures were performed for 23% of the patients. The most common procedures included pacemaker implantations among infants with NLE, coronary artery bypass grafts for KD primarily in 5- to 15-year-olds, and cardiac valve operations among adolescents with RHD, SLE, and JRA. Six perioperative deaths occurred. The proportion of annual pediatric cardiac surgical volume attributable to rheumatic diseases did not change during the period studied. Despite advances in their medical care, children with rheumatic diseases continue to sustain measurable morbidity and mortality due to the cardiovascular manifestations of their disease. PMID:19967351

  10. Cardiac arrest management

    Microsoft Academic Search

    Richard V. Aghababian; Gregory Mears; Joseph P. Ornato; Peter J. Kudenchuk

    2001-01-01

    Approximately 1,000 people in the United States suffer cardiac arrest each day, most often as a complication of acute myocardial infarction (AMI) with accompanying ventricular fibrillation or unstable ventricular tachycardia. Increasing the number of patients who survive cardiac arrest and minimizing the clinical sequelae associated with cardiac arrest in those who do survive are the objectives of emergency medical personnel.

  11. Baf250a orchestrates an epigenetic pathway to repress the Nkx2.5-directed contractile cardiomyocyte program in the sinoatrial node

    PubMed Central

    Wu, Meng; Peng, Siwu; Yang, Jialiang; Tu, Zhidong; Cai, Xiaoqiang; Cai, Chen-Leng; Wang, Zhong; Zhao, Yong

    2014-01-01

    The sinoatrial node (SAN) is essential for rhythmic beating of the heart; however, our understanding of what controls proper functioning of the SAN remains primitive. To explore molecular control of SAN function, we specifically deleted Baf250a, a key regulatory component of the ATP-dependent chromatin remodeling complex SWI/SNF, in the SAN. Deletion of Baf250a in the SAN led to sinus bradycardia. Time series analysis of dysregulated genes after deletion of Baf250a reveals a transcriptional hierarchy maintaining pacemaker cell identity, i.e., Baf250a activates the expression of Tbx3, and Baf250a, Tbx3 and histone deacetylase 3 coordinately repress the expression of Nkx2.5. Disruption of this repressive pathway switches on expression of Nkx2.5, which stimulates expression of Gata4 and Tbx5. These three cardiac transcription factors further turn on a contractile cardiomyocyte program in the SAN, which eventually leads to sick sinus disease (SSD). Our study suggests that disruption of key genetic pathways regulating cardiac lineage segregation may cause SSD and cardiac arrhythmias in general. PMID:25145359

  12. Temperate Drosophila preserve cardiac function at low temperature.

    PubMed

    Andersen, Jonas Lembcke; MacMillan, Heath Andrew; Overgaard, Johannes

    2015-06-01

    Most insects are chill susceptible and will enter a coma if exposed to sufficiently low temperature. This chill coma has been associated with a failure of the neuromuscular system. Insect heart rate (HR) is determined by intrinsic regulation (muscle pacemaker) with extrinsic (nervous and humoral) input. By examining the continually active heart of five Drosophila species with markedly different cold tolerance, we investigated whether cardiac performance is related to the whole animal critical thermal minimum (CTmin). Further, to separate the effects of cold on extrinsic and intrinsic regulators of HR, we measured HR under similar conditions in decapitated flies as well as amputated abdomens of Drosophila montana. Cardiac performance was assessed from break points in HR-temperature relationship (Arrhenius break point, ABP) and from the HR cessation temperature. Among the five species, we found strong relationships for both the HR-ABP and HR cessation temperatures to whole animal CTmin, such that temperate Drosophila species maintained cardiac function at considerably lower temperatures than their tropical congeners. Hearts of amputated abdomens, with reduced extrinsic input, had a higher thermal sensitivity and a significantly lower break point temperature, suggesting that central neuronal input is important for stimulating HR at low temperatures. PMID:25871726

  13. [Development and importance of outpatient cardiac rehabilitation in German-speaking countries].

    PubMed

    Benzer, W

    2014-07-01

    Cardiac rehabilitation is a coordinated treatment approach. The interdisciplinary team aims to provide the best possible physical and psychological outcomes for patients with cardiac diseases. Patients should be enable to independently resume work and and social life. Furthermore cardiac rehabilitation wants to limit or reverse the progress of cardiac disease through sustained health-related life habits. Cardiac rehabilitation significantly contributes to long-term success based on comprehensive care of cardiac patients. Outpatient cardiac rehabilitation has shown to be effective after myocardial infarction, coronary artery bypass grafting and chronic heart failure. However randomized controlled trials were performed only in Anglo-American countries. In these trials effects were observed mainly for exercise-based cardiac rehabilitation programs. Because the results have been derived from different program settings they cannot simply be translated to German-speaking countries. However, several cohort studies predominantly performed in Germany also revealed effects of inpatient and outpatient cardiac rehabilitation programs for German-speaking countries. The most recent results demonstrated a significant reduction of recurrent events in patients after inpatient cardiac rehabilitation. Following the current evidence concerning the effect of inpatient and outpatient cardiac rehabilitation programs particularly after myocardial infarction international guidelines provide Class I (USA) and IIa (Europe) recommendation for this treatment intervention.In contrast to Anglo-American countries cardiac rehabilitation in Austria, Germany and Switzerland was established at its beginning exclusively for inpatient programs. In addition more and more outpatient programs were introduced in the last decades. Nevertheless inpatient cardiac rehabilitation is still the most common program in German-speaking countries.Future challenges of cardiac rehabilitation should not address the competition between inpatient and outpatient programs but provide answers to the question "which patient needs which program?" Future cardiac rehabilitation will offer patient-tailored programs. In German-speaking countries inpatient cardiac rehabilitation has long been well established whereas treatment potential of outpatient programs have increased. Outpatient cardiac rehabilitation is more flexible, close to home and it can be done part-time. Furhtermore, outpatient cardiac rehabilitation programs can take on important tasks in long-term cardiac care and thus provide relief to inpatient programs. The initiation of such programs is a challenge and can add to better future development of comprehensive cardiac rehabilitation. PMID:24937081

  14. Temporary cardiac pacing for fatal arrhythmia in living-donor liver transplantation: three case reports.

    PubMed

    Kobayashi, T; Sato, Y; Yamamoto, S; Oya, H; Takeishi, T; Kokai, H; Hatakeyama, K

    2008-10-01

    Cardiac pacing often turns out to be the only effective treatment of severe, life-threatening arrhythmias. We performed 77 living-donor liver transplantations (LDLT) from 1999 to 2007. In these cases, three recipients experienced fatal arrhythmia and required temporary cardiac pacing during the perioperative period. The first case was a 68-year-old woman diagnosed with liver cirrhosis and hepatocellular carcinoma (HCC). Her Model for End-Stage Liver Disease (MELD) score was 34. We performed LDLT using a right lobe graft. She showed complete atrioventricular block with cardiac arrest at postoperative day (POD) 42 after a bacterial infection. We performed a resuscitation and instituted temporary cardiac pacing. However, she was dead at POD 43. Pathologic findings at autopsy showed a diffuse myocardial abscess, which caused the fatal arrhythmia. The second case was a 58-year-old man diagnosed with HCC and liver cirrhosis; his MELD score was 9. We performed LDLT using a right lobe graft. He showed atrial fibrillation after septic shock. He also showed sinus bradycardia with a cardiac arrest at POD 10. We performed resuscitation and emergent temporary pacing. He recovered and was alive without recurrence of arrhythmia or infection. The third case was a 58-year-old woman diagnosed with multiple HCC. During preoperative regular check-up, she was diagnosed to have cardiac hypertrophy and was started on beta-blockers as treatment for cardiac hypertrophy. However, severe bradycardia necessitated temporary cardiac pacing. LDLT was performed safely after implantation of a pacemaker. Early use of temporary cardiac pacing for severe arrhythmias may be effective to maintain the hemodynamic state in LDLT. PMID:18929869

  15. Controlled Cardiac Computed Tomography

    PubMed Central

    Wang, Chenglin; Liu, Ying; Wang, Ge

    2006-01-01

    Cardiac computed tomography (CT) has been a hot topic for years because of the clinical importance of cardiac diseases and the rapid evolution of CT systems. In this paper, we propose a novel strategy for controlled cardiac CT that may effectively reduce image artifacts due to cardiac and respiratory motions. Our approach is radically different from existing ones and is based on controlling the X-ray source rotation velocity and powering status in reference to the cardiac motion. We theoretically show that by such a control-based intervention the data acquisition process can be optimized for cardiac CT in the cases of periodic and quasiperiodic cardiac motions. Specifically, we formulate the corresponding coordination/control schemes for either exact or approximate matches between the ideal and actual source positions, and report representative simulation results that support our analytic findings. PMID:23165017

  16. Modes of induced cardiac arrest: hyperkalemia and hypocalcemia - Literature review

    PubMed Central

    de Oliveira, Marcos Aurélio Barboza; Brandi, Antônio Carlos; dos Santos, Carlos Alberto; Botelho, Paulo Henrique Husseini; Cortez, José Luis Lasso; Braile, Domingo Marcolino

    2014-01-01

    The entry of sodium and calcium play a key effect on myocyte subjected to cardiac arrest by hyperkalemia. They cause cell swelling, acidosis, consumption of adenosine triphosphate and trigger programmed cell death. Cardiac arrest caused by hypocalcemia maintains intracellular adenosine triphosphate levels, improves diastolic performance and reduces oxygen consumption, which can be translated into better protection to myocyte injury induced by cardiac arrest. PMID:25372919

  17. Review of radiation safety in the cardiac catheterization laboratory

    SciTech Connect

    Johnson, L.W.; Moore, R.J.; Balter, S. (St. Joseph's Hospital Health Center, Syracuse, NY (United States))

    1992-03-01

    With the increasing use of coronary arteriography and interventional procedures, radiation exposure to patients and personnel working in cardiac catheterization laboratories has increased. Proper technique to minimize both patient and operator exposure is necessary. A practical approach to radiation safety in the cardiac catheterization laboratory is presented. This discussion should be useful to facilities with well-established radiation safety programs as well as facilities that require restructuring to cope with the radiation environment in a modern cardiac catheterization laboratory.

  18. Measuring cardiac waste: the premier cardiac waste measures.

    PubMed

    Lowe, Timothy J; Partovian, Chohreh; Kroch, Eugene; Martin, John; Bankowitz, Richard

    2014-01-01

    The authors developed 8 measures of waste associated with cardiac procedures to assist hospitals in comparing their performance with peer facilities. Measure selection was based on review of the research literature, clinical guidelines, and consultation with key stakeholders. Development and validation used the data from 261 hospitals in a split-sample design. Measures were risk adjusted using Premier's CareScience methodologies or mean peer value based on Medicare Severity Diagnosis-Related Group assignment. High variability was found in resource utilization across facilities. Validation of the measures using item-to-total correlations (range = 0.27-0.78), Cronbach ? (.88), and Spearman rank correlation (0.92) showed high reliability and discriminatory power. Because of the level of variability observed among hospitals, this study suggests that there is opportunity for facilities to design successful waste reduction programs targeting cardiac-device procedures. PMID:23719033

  19. Usefulness of clinical and electrocardiographic data for predicting adverse cardiac events in patients with myotonic dystrophy

    PubMed Central

    Breton, Robert; Mathieu, Jean

    2009-01-01

    BACKGROUND: Myotonic dystrophy type 1 (DM1) has been associated with an increased risk of sudden death, either by heart block or malignant ventricular arrhythmias. Identifying patients at risk remains difficult and no consensus has been reached regarding the best approach for follow-up and prevention of sudden death. OBJECTIVES: To identify noninvasive clinical and electrocardiographic predictors of adverse cardiac events in patients with DM1. METHODS: Clinical and serial electrocardiographic data on 428 patients with a DNA-proven diagnosis of DM1, followed during a mean period of 11.7 years, were reviewed. Variables associated with adverse cardiac events were identified. RESULTS: Eleven patients (2.6%) experienced sudden death and 13 (3.0%) required implantation of a pacemaker. On univariate analysis, adverse events were associated with advancing age, prolongation of the PR, QRS and corrected QT (QTc) intervals, as well as the degree of neuromuscular impairment. No such relationship was found with the extent of genetic anomaly (number of cytosine-thymine-guanine repeats). However, multivariate analysis using Cox proportional hazards models showed that only baseline PR and QTc intervals were significantly linked to the end points of sudden death or pacemaker implantation; the age-adjusted RR was 3.7 (95% CI 1.5 to 8.6) if baseline PR was 200 ms or longer (P=0.003), and 3.0 (95% CI 1.0 to 8.8) if the baseline QTc was 450 ms or longer (P=0.047). CONCLUSIONS: In a large unselected cohort of 428 patients with DM1, the cumulative incidence of sudden death was relatively low, and the delayed conduction on surface electrocardiogram was found to be potentially helpful for identifying patients at risk for sudden death or pacemaker implantation. PMID:19214296

  20. Effects of ibutilide on canine cardiac pacing threshold and on induction rates of atrial fibrillation.

    PubMed

    Sun, Jian-ling; Han, Rong; Guo, Ji-hong; Li, Xiao-ying; Ma, Xian-lin; Wang, Chong-yu

    2012-12-01

    This study aims to observe the effects of ibutilide on canine cardiac pacing threshold and on induction rates of atrial fibrillation. Eighteen mongrel dogs were anesthetized and administrated with ibutilide. The pacing thresholds and induction rates of atrial fibrillation were measured with and without ibutilide (10-min infusion dose was 0.10 mg kg(-1), followed by a maintaining dose of 0.01 mg min(-1) 30 min later). This study found that ibutilide increases pacing thresholds in dogs. Moreover, there were significant differences between pacing thresholds with and without ibutilide (P < 0.05). Further, ibutilide significantly reduces the induction rates of atrial fibrillation (P < 0.05). Our findings indicate that pacing voltage changes should be closely monitored in patients taking anti-arrhythmic drugs, who are treated with cardiac stimulation or have undergone pacemaker implantation. We also found that ibutilide is an effective drug in preventing or controlling atrial fibrillation. PMID:22740072

  1. Towards an atrio-ventricular delay optimization assessed by a computer model for cardiac resynchronization therapy

    NASA Astrophysics Data System (ADS)

    Ojeda, David; Le Rolle, Virginie; Tse Ve Koon, Kevin; Thebault, Christophe; Donal, Erwan; Hernández, Alfredo I.

    2013-11-01

    In this paper, lumped-parameter models of the cardiovascular system, the cardiac electrical conduction system and a pacemaker are coupled to generate mitral ow pro les for di erent atrio-ventricular delay (AVD) con gurations, in the context of cardiac resynchronization therapy (CRT). First, we perform a local sensitivity analysis of left ventricular and left atrial parameters on mitral ow characteristics, namely E and A wave amplitude, mitral ow duration, and mitral ow time integral. Additionally, a global sensitivity analysis over all model parameters is presented to screen for the most relevant parameters that a ect the same mitral ow characteristics. Results provide insight on the in uence of left ventricle and atrium in uence on mitral ow pro les. This information will be useful for future parameter estimation of the model that could reproduce the mitral ow pro les and cardiovascular hemodynamics of patients undergoing AVD optimization during CRT.

  2. Cardiac innervation and sudden cardiac death.

    PubMed

    Fukuda, Keiichi; Kanazawa, Hideaki; Aizawa, Yoshiyasu; Ardell, Jeffrey L; Shivkumar, Kalyanam

    2015-06-01

    Afferent and efferent cardiac neurotransmission via the cardiac nerves intricately modulates nearly all physiological functions of the heart (chronotropy, dromotropy, lusitropy, and inotropy). Afferent information from the heart is transmitted to higher levels of the nervous system for processing (intrinsic cardiac nervous system, extracardiac-intrathoracic ganglia, spinal cord, brain stem, and higher centers), which ultimately results in efferent cardiomotor neural impulses (via the sympathetic and parasympathetic nerves). This system forms interacting feedback loops that provide physiological stability for maintaining normal rhythm and life-sustaining circulation. This system also ensures that there is fine-tuned regulation of sympathetic-parasympathetic balance in the heart under normal and stressed states in the short (beat to beat), intermediate (minutes to hours), and long term (days to years). This important neurovisceral/autonomic nervous system also plays a major role in the pathophysiology and progression of heart disease, including heart failure and arrhythmias leading to sudden cardiac death. Transdifferentiation of neurons in heart failure, functional denervation, cardiac and extracardiac neural remodeling has also been identified and characterized during the progression of disease. Recent advances in understanding the cellular and molecular processes governing innervation and the functional control of the myocardium in health and disease provide a rational mechanistic basis for the development of neuraxial therapies for preventing sudden cardiac death and other arrhythmias. Advances in cellular, molecular, and bioengineering realms have underscored the emergence of this area as an important avenue of scientific inquiry and therapeutic intervention. PMID:26044253

  3. Cardiac safety of high voltage TASER X26 waveform

    Microsoft Academic Search

    R. Stracbucker; R. Roeder; M. Nerheim

    2003-01-01

    This paper covers the cardiac safety studies of a high voltage (TASER) less-lethal weapon, and outlines the safety margin of the Taser X26. The cardiac safety test protocol was based on the rigorous safety protocol required by the Office of Naval Research for government funded basic science oriented research program.

  4. Lack of intestinal pacemaker (C-KIT-positive) cells in infantile hypertrophic pyloric stenosis

    Microsoft Academic Search

    Atsuyuki Yamataka; Toshio Fujiwara; Yoshifumi Kato; Tadaharu Okazaki; Masakatsu Suhagawa; Takeshi Miyano

    1996-01-01

    The pathogenesis of infantile hypertrophic pyloric stenosis (IHPS) is not well understood. Recent studies have shown that the protooncogene c-kit is essential for the development or maintenance of autonomic gut motility, and also show that the c-kit gene protein product (C-KIT) positive cells in the mammalian gut are responsible for intestinal pacemaker activity. This study examines cells in the pyloric

  5. Safety and cost-effectiveness of same day permanent pacemaker implantation.

    PubMed

    Osman, Faizel; Krishnamoorthy, Suresh; Nadir, Adnan; Mullin, Phillip; Morley-Davies, Adrian; Creamer, John

    2010-08-01

    An overnight stay after permanent pacemaker implantation has major cost implications for healthcare systems. Same day pacing could be effective in alleviating this. We evaluated our elective same day pacing practice to determine safety and cost-effectiveness. A total of 780 patients were scheduled for elective new permanent pacemaker implantation as a same day procedure at the University Hospital, North Staffordshire, from April 2001 to December 2006. The mean age +/- SEM of the cohort was 73.8 +/- 0.4 years (464 men and 316 women). Single-chamber devices were implanted in 272 (27 atrial and 245 ventricular) and dual chamber in 508 patients. Vascular access was by the subclavian vein in 431 patients and the cephalic vein in 349. Preimplant intravenous antibiotics were administered to 28% and perioperative antibiotics to the remainder; all patients received oral antibiotics after implantation. Of the 780 patients, 41 (5.3%) required an in-hospital stay after implantation because of hematoma formation in 12, pneumothorax in 3, social reasons for 7, observation at the physicians request but no complication for 13, angina in 3, arrhythmia in 1, and warfarin therapy in 2. Immediate complications (<24 hours) occurred in 6 patients and early complications (>24 hours to 6 weeks) developed in 17. Of the 780 patients, 94 had died at mean follow-up of 2.4 +/- 0.1 years; none were related to pacemaker implantation. An overnight stay at our hospital costs pound203.60 ( approximately US$305). From November 2005 to November 2006, 109 patients underwent same day implantation, resulting in a cost saving of pound22,192.40 ( approximately US$34,500). In conclusion, same day permanent pacemaker implantation was feasible, safe, and cost-effective. It was associated with a low prevalence of complications and only a few patients required an overnight stay. PMID:20643250

  6. Phase-shifting of a neuronal circadian pacemaker in Bulla gouldiana by pentylenetetrazol.

    PubMed

    Khalsa, S B; Block, G D

    1992-04-01

    1. The convulsant agent pentylenetetrazol generates compound action potential activity from the circadian pacemaker cells in the Bulla retina. 2. The phase response curve to 3 hr pulses of pentylenetetrazol consists of only phase delays which occur following pulses delivered in the early subjective night. 3. Phase shifts to pentylenetetrazol are independent of extracellular calcium since they persist in a low-calcium EGTA solution. PMID:1354133

  7. Spontaneous displacement of a pacemaker electrode and its subsequent successful reimplantation.

    PubMed Central

    Gialafos, J; Theophilis, A; Siamas, G

    1989-01-01

    A case of what was assumed to be twiddler's syndrome was caused by spontaneous twisting and displacement of the electrode on the fortieth postoperative day. The pacemaker had not been manipulated by the patient, the pocket was tight, and the proximal electrode was well secured. The complication was managed successfully by reimplanting the same electrode after stiffening the lead near the generator with a portion of the stylet. Images Fig 1 Fig 2 PMID:2590595

  8. Modulation of pacemaker activity by IPSP and brief length perturbations in the crayfish stretch receptor.

    PubMed

    Buño, W; Fuentes, J; Barrio, L

    1987-03-01

    We have studied the influences of brief stretches and releases and of inhibitory postsynaptic potentials (IPSPs) on pacemaker activity of the crayfish stretch receptor (RM1). Stimuli shift or reset the ongoing rhythm. Resettings were different if evaluated in interspike intervals containing perturbations, or in succeeding ones, and are referred to as early and late, respectively. Early resetting revealed that stretches and releases or IPSPs advance and delay, respectively, the next spike. With small stretches and releases or IPSPs, effects depend on the timing of the perturbation relative to the previous spike or phase, but above a characteristic mechanical perturbation amplitude the next spike fires at a fixed latency, invariant with the phase. Of particular interest was the finding that during late resetting the first successive intervals following stretches and releases or IPSPs were longer and shorter, respectively, than the period. This led, in approximately 50% of the cases, to a gradual recovery of the original pacemaker beat in the sense that spikes fire timed as if the early rhythm shift had not occurred. In conclusion, the recent firing history is essential in determining the RM1's response. The receptor's sensitivity is a complex nonlinear and periodic function of the pacemaker activity, and the response is due to interactions between pacemaker- and perturbation-induced transmembrane ionic currents. Although several alternative mechanisms may underly beat recovery, the results suggest that at least two coupled oscillators, one perturbable and the other not, provide a better explanation than a single oscillator. The physiological significance of resettings is unknown, but the early rhythm shift may synchronize RM1s in several segments when the animal's tail is moved, and conversely recovery would reduce synchrony, with obvious influences on shared postsynaptic neurons. PMID:3031234

  9. Taser-Induced Rapid Ventricular Myocardial Capture Demonstrated by Pacemaker Intracardiac Electrograms

    Microsoft Academic Search

    MICHAEL CAO; JEROLD S. SHINBANE; JEFFREY M. GILLBERG; LESLIE A. SAXON

    2007-01-01

    Taser-Induced Myocardial Capture. Introduction :A Taser weapon is designed to incapacitate vio- lent individuals by causing temporary neuromuscular paralysis due to current application. We report the first case of a Taser application in a person with a dual-chamber pacemaker demonstrating evidence of Taser-induced myocardial capture. Methods and Results :D evice interrogation was performed in a 53-year-old man with a dual-chamber

  10. Traveling waves and dynamical formation of autonomous pacemakers in a bistable medium with periodic boundary conditions

    NASA Astrophysics Data System (ADS)

    Shepelev, Igor A.; Vadivasova, Tatiana E.; Postnov, Dmitry E.

    2015-03-01

    The problem of spatiotemporal pattern formation in the wall of arterial vesselsmay be reduced to 1D or 2D models of nonlinear active medium. We address this problem using the discrete array of non-oscillating (bistable) active units. We show how the specific choice of initial conditions in a 1D model with periodic boundary conditions triggers the self-sustained behaviour. We reveal the core of observed effects being the dynamical formation of localized (few-element size) autonomous pacemakers.

  11. Lability of circadian pacemaker amplitude in chick pineal cells: a temperature-dependent process.

    PubMed

    Barrett, R K; Takahashi, J S

    1997-08-01

    Temperature is a major regulator of circadian rhythms. The authors report here three lines of evidence that temperature modulates the amplitude of the circadian pacemaker that drives rhythmic melatonin production in chick pineal cells. (1) The melatonin rhythm persists longer in constant conditions at 40 degrees C than at 37 degrees C. (2) the phase response curve to low-intensity (0.15 microW/cm2) light pulses of 6-h duration has a higher amplitude at 37 degrees C than at 40 degrees C; a nonphotic stimulus, anisomycin, also causes larger shifts at 37 degrees C than at 40 degrees C. These results suggest a general increase in sensitivity to phase-shifting stimuli as temperature decreases. (3) The light intensity necessary for a critical pulse that causes arrhythmicity is lower at 37 degrees C than at 40 degrees C. All three of these effects of temperature can be explained in a unified manner by a limit cycle model in which temperature increases circadian pacemaker amplitude. The use of critical pulse experiments provides a novel method for estimating relative circadian pacemaker amplitude under different conditions. PMID:9438879

  12. 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

  13. Pacemaker-guided noise-induced spatial periodicity in excitable media

    NASA Astrophysics Data System (ADS)

    Gosak, Marko; Marhl, Marko; Perc, Matjaž

    2009-03-01

    We study the impact of subthreshold periodic pacemaker activity and internal noise on the spatial dynamics of excitable media. For this purpose, we examine two systems that both consist of diffusively coupled units. In the first case, the local dynamics of the units is driven by a simple one-dimensional model of excitability with a piece-wise linear potential. In the second case, a more realistic biological system is studied, and the local dynamics is driven by a model for calcium oscillations. Internal noise is introduced via the ?-leap stochastic integration procedure and its intensity is determined by the finite size of each constitutive system unit. We show that there exists an intermediate level of internal stochasticity for which the localized pacemaker activity maps best into coherent periodic waves, whose spatial frequency is uniquely determined by the local subthreshold forcing. Via an analytical treatment of the simple minimal model for the excitable spatially extended system, we explicitly link the pacemaker activity with the spatial dynamics and determine necessary conditions that warrant the observation of the phenomenon in excitable media. Our results could prove useful for the understanding of interplay between local and global agonists affecting the functioning of tissue and organs.

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

    PubMed

    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 "Ca(2+)-clock" rhythmically discharges diastolic local Ca(2+) releases (LCRs) beneath the cell surface membrane. LCRs activate an inward current (likely that of the Na(+)/Ca(2+) 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

  15. Cardiac Device Implantation in the United States from 1997 through 2004: A Population-based Analysis

    PubMed Central

    Baine, William B.; Sedrakyan, Artyom; Steiner, Claudia

    2007-01-01

    OBJECTIVE Use of cardiac devices has been increasing rapidly along with concerns over their safety and effectiveness. This study used hospital administrative data to assess cardiac device implantations in the United States, selected perioperative outcomes, and associated patient and hospital characteristics. METHODS We screened hospital discharge abstracts from the 1997–2004 Healthcare Cost and Utilization Project Nationwide Inpatient Samples. Patients who underwent implantation of pacemaker (PM), automatic cardioverter/defibrillator (AICD), or cardiac resynchronization therapy pacemaker (CRT-P) or defibrillator (CRT-D) were identified using ICD-9-CM procedure codes. Outcomes ascertainable from these data and associated hospital and patient characteristics were analyzed. MEASUREMENTS AND MAIN RESULTS Approximately 67,000 AICDs and 178,000 PMs were implanted in 2004 in the United States, increasing 60% and 19%, respectively, since 1997. After FDA approval in 2001, CRT-D and CRT-P reached 33,000 and 7,000 units per year in the United States in 2004. About 70% of the patients were aged 65 years or older, and more than 75% of the patients had 1 or more comorbid diseases. There were substantial decreases in length of stay, but marked increases in charges, for example, the length of stay of AICD implantations halved (from 9.9 days in 1997 to 5.2 days in 2004), whereas charges nearly doubled (from $66,000 in 1997 to $117,000 in 2004). Rates of in-hospital mortality and complications fluctuated slightly during the period. Overall, adverse outcomes were associated with advanced age, comorbid conditions, and emergency admissions, and there was no consistent volume–outcome relationship across different outcome measures and patient groups. CONCLUSIONS The numbers of cardiac device implantations in the United States steadily increased from 1997 to 2004, with substantial reductions in length of stay and increases in charges. Rates of in-hospital mortality and complications changed slightly over the years and were associated primarily with patient frailty. PMID:18095038

  16. Hyperplastic cardiac sarcoma recurrence.

    PubMed

    Shariff, Masood A; Abreu, Juan A; Durrani, Farida; Daniele, Eddie; Bowman, Kimberly C; Sadel, Scott; Asgarian, Kourosh T; McGinn, Joseph T; Nabagiez, John P

    2015-01-01

    Primary cardiac sarcomas are rare tumors with a median survival of 6-12 months. Data suggest that an aggressive multidisciplinary approach may improve patient outcome. We present the case of a male who underwent resection of cardiac sarcoma three times from the age of 32 to 34. This report discusses the malignant nature of cardiac sarcoma and the importance of postoperative multidisciplinary care. PMID:25861508

  17. Favourable cost-benefit in an early defibrillation program using dual dispatch of ambulance and fire services in out-of-hospital cardiac arrest

    Microsoft Academic Search

    Björn Sund; Leif Svensson; Mårten Rosenqvist; Jacob Hollenberg

    2010-01-01

    Aims: Out-of-hospital cardiac arrest (OHCA) is fatal without treatment and time to defibrillation is an extremely important factor in relation to survival. We performed a cost-benefit analysis of dual dispatch defibrillation by ambulance and fire services in the County of Stockholm, Sweden. Methods and Results: A cost-benefit analysis was performed to evaluate the effects of dual dispatch defibrillation. The increased

  18. Cardiac risk telemonitoring

    Microsoft Academic Search

    H. Hutten; M. Hribernigg; G. Rauchegger

    2001-01-01

    Utilization of advanced information, telecommunication and implant technology for cardiac risk stratification and management is one of the greatest challenges for modern health care provision. Sudden cardiac death is the major contributor to overall cardiovascular mortality with approximately 60% of all coronary heart disease fatalities occurring annually. Although some high-risk patient groups have been identified with reasonable sensitivity and specificity

  19. Garfinkel Cardiac Data

    NSDL National Science Digital Library

    Alan Garfinkel (University of California Los Angeles; Physiological Sci/Med-Cardio)

    2009-01-10

    Cardiac data on multiple variables for a selected population of 220 men and 338 women participating in a drug treatment study of dobutamine for heart attack prevention. Garfinkel, Alan, et. al. "Prognostic Value of Dobutamine Stress Echocardiography in Predicting Cardiac Events in Patients With Known or Suspected Coronary Artery Disease." Journal of the American College of Cardiology 33.3 (1999) 708-16.

  20. Pacemaker phase shift in the absence of neural activity in guinea-pig stomach: a microelectrode array study

    PubMed Central

    Nakayama, Shinsuke; Shimono, Ken; Liu, Hong-Nian; Jiko, Hideyasu; Katayama, Noburu; Tomita, Tadao; Goto, Kazunori

    2006-01-01

    Gastrointestinal (GI) motility is well organized. GI muscles act as a functional syncytium to achieve physiological functions under the control of neurones and pacemaker cells, which generate basal spontaneous pacemaker electrical activity. To date, it is unclear how spontaneous electrical activities are coupled, especially within a micrometre range. Here, using a microelectrode array, we show a spatio-temporal analysis of GI spontaneous electrical activity. The muscle preparations were isolated from guinea-pig stomach, and fixed in a chamber with an array of 8 × 8 planar multielectrodes (with 300 ?m in interpolar distance). The electrical activities (field potentials) were simultaneously recorded through a multichannel amplifier system after high-pass filtering at 0.1 Hz. Dihydropyridine Ca2+ channel antagonists are known to differentiate the electrical pacemaker activity of interstitial cells of Cajal (ICCs) by suppressing smooth muscle activity. In the presence of nifedipine, we observed spontaneous electrical activities that were well synchronized over the array area, but had a clear phase shift depending on the distance. The additional application of tetrodotoxin (TTX) had little effect on the properties of the electrical activity. Furthermore, by constructing field potential images, we visualized the synchronization of pacemaker electrical activities resolving phase shifts that were measurable over several hundred micrometres. The results imply a phase modulation mechanism other than neural activity, and we postulate that this mechanism enables smooth GI motility. In addition, some preparations clearly showed plasticity of the pacemaker phase shift. PMID:16990400

  1. Modeling inherited cardiac disorders.

    PubMed

    Sallam, Karim; Kodo, Kazuki; Wu, Joseph C

    2014-01-01

    Advances in the understanding and treatment of cardiac disorders have been thwarted by the inability to study beating human cardiac cells in vitro. Induced pluripotent stem cells (iPSCs) bypass this hurdle by enabling the creation of patient-specific iPSC-derived cardiomyocytes (iPSC-CMs). These cells provide a unique platform to study cardiac diseases in vitro, especially hereditary cardiac conditions. To date, iPSC-CMs have been used to successfully model arrhythmic disorders, showing excellent recapitulation of cardiac channel function and electrophysiologic features of long QT syndrome types 1, 2, 3, and 8, and catecholaminergic polymorphic ventricular tachycardia (CPVT). Similarly, iPSC-CM models of dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM) have shown robust correlation of predicted morphologic, contractile, and electrical phenotypes. In addition, iPSC-CMs have shown some features of the respective phenotypes for arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C), LEOPARD syndrome, Pompe's disease, and Friedriech's ataxia. In this review, we examine the progress of utilizing iPSC-CMs as a model for cardiac conditions and analyze the potential for the platform in furthering the biology and treatment of cardiac disorders.?? PMID:24632794

  2. Surgical management of superior vena cava syndrome following pacemaker lead infection: a case report and review of the literature.

    PubMed

    Kokotsakis, John; Chaudhry, Umar A R; Tassopoulos, Dimitris; Harling, Leanne; Ashrafian, Hutan; Vernandos, Michail; Kanakis, Meletis; Athanasiou, Thanos

    2014-01-01

    Superior vena cava (SVC) syndrome is a known but rare complication of pacemaker lead implantation, accounting for approximately less than 0.5% of cases. Its pathophysiology is due to either infection or endothelial mechanical stress, causing inflammation and fibrosis leading to thrombosis, and therefore stenosis of the SVC. Due to the various risks including thrombo-embolic complications and the need to provide symptomatic relief, medical and surgical interventions are sought early. We present the case of a 48-year Caucasian male who presented with localised swelling and pain at the site of pacemaker implantation. Inflammatory markers were normal, but diagnostic imaging revealed three masses along the pacemaker lead passage. A surgical approach using cardiopulmonary bypass and circulatory arrest was used to remove the vegetations. Culture from the vegetations showed Staphylococcus epidermidis. The technique presented here allowed for safe and effective removal of both the thrombus and infected pacing leads, with excellent exposure and minimal post-procedure complications. PMID:24947452

  3. Identification of Bacteriology and Risk Factor Analysis of Asymptomatic Bacterial Colonization in Pacemaker Replacement Patients

    PubMed Central

    Chu, Xian-Ming; Yu, Hua; Sun, Xue-Xia; An, Yi; Li, Bing; Li, Xue-Bin

    2015-01-01

    Background Recent researches revealed that asymptomatic bacterial colonization on PMs might be ubiquitous and increase the risk of clinical PM infection. Early diagnosis of patients with asymptomatic bacterial colonization could provide opportunity for targeted preventive measures. Objective The present study explores the incidence of bacterial colonization of generator pockets in pacemaker replacement patients without signs of infection, and to analyze risk factors for asymptomatic bacterial colonization. Methods From June 2011 to December 2013, 118 patients underwent pacemaker replacement or upgrade. Identification of bacteria was carried out by bacterial culture and 16S rRNA sequencing. Clinical risk characteristics were analyzed. Results The total bacterial positive rate was 37.3% (44 cases), and the coagulase-negative Staphylococcus aureus detection rate was the highest. Twenty two (18.6%) patients had positive bacterial culture results, of which 50% had coagulase-negative staphylococcus. The bacterial DNA detection rate was 36.4 % (43 cases). Positive bacterial DNA results from pocket tissues and the surface of the devices were 22.0% and 29.7%, respectively. During follow-up (median, 27.0 months), three patients (6.8%, 3/44) became symptomatic with the same genus of microorganism, S. aureus (n=2) and S. epidermidis (n=1). Multivariable logistic regression analysis showed that history of bacterial infection, use of antibiotics, application of antiplatelet drugs, replacement frequency were independent risk factors for asymptomatic bacterial colonization. Conclusion There was a high incidence of asymptomatic bacterial colonization in pacemaker patients with independent risk factors. Bacterial culture combined genetic testing could improve the detection rate. PMID:25768661

  4. The emergence of subcellular pacemaker sites for calcium waves and oscillations

    PubMed Central

    Nivala, Michael; Ko, Christopher Y; Nivala, Melissa; Weiss, James N; Qu, Zhilin

    2013-01-01

    Calcium (Ca2+) waves generating oscillatory Ca2+ signals are widely observed in biological cells. Experimental studies have shown that under certain conditions, initiation of Ca2+ waves is random in space and time, while under other conditions, waves occur repetitively from preferred locations (pacemaker sites) from which they entrain the whole cell. In this study, we use computer simulations to investigate the self-organization of Ca2+ sparks into pacemaker sites generating Ca2+ oscillations. In both ventricular myocyte experiments and computer simulations of a heterogeneous Ca2+ release unit (CRU) network model, we show that Ca2+ waves occur randomly in space and time when the Ca2+ level is low, but as the Ca2+ level increases, waves occur repetitively from the same sites. Our analysis indicates that this transition to entrainment can be attributed to the fact that random Ca2+ sparks self-organize into Ca2+ oscillations differently at low and high Ca2+ levels. At low Ca2+, the whole cell Ca2+ oscillation frequency of the coupled CRU system is much slower than that of an isolated single CRU. Compared to a single CRU, the distribution of interspike intervals (ISIs) of the coupled CRU network exhibits a greater variation, and its ISI distribution is asymmetric with respect to the peak, exhibiting a fat tail. At high Ca2+, however, the coupled CRU network has a faster frequency and lesser ISI variation compared to an individual CRU. The ISI distribution of the coupled network no longer exhibits a fat tail and is well-approximated by a Gaussian distribution. This same Ca2+ oscillation behaviour can also be achieved by varying the number of ryanodine receptors per CRU or the distance between CRUs. Using these results, we develop a theory for the entrainment of random oscillators which provides a unified explanation for the experimental observations underlying the emergence of pacemaker sites and Ca2+ oscillations. PMID:24042497

  5. Beam Profile Disturbances from Implantable Pacemakers or Implantable Cardioverter-Defibrillator Interactions

    SciTech Connect

    Gossman, Michael S., E-mail: mgossman@tsrcc.com [Tri-State Regional Cancer Center, Medical Physics Section, Ashland, KY (United States); Comprehensive Heart and Vascular Associates, Heart and Vascular Center, Ashland, KY (United States); Medtronic, Inc., External Research Program, Mounds View, MN (United States); Nagra, Bipinpreet; Graves-Calhoun, Alison; Wilkinson, Jeffrey [Tri-State Regional Cancer Center, Medical Physics Section, Ashland, KY (United States); Comprehensive Heart and Vascular Associates, Heart and Vascular Center, Ashland, KY (United States); Medtronic, Inc., External Research Program, Mounds View, MN (United States)

    2011-01-01

    The medical community is advocating for progressive improvement in the design of implantable cardioverter-defibrillators and implantable pacemakers to accommodate elevations in dose limitation criteria. With advancement already made for magnetic resonance imaging compatibility in some, a greater need is present to inform the radiation oncologist and medical physicist regarding treatment planning beam profile changes when such devices are in the field of a therapeutic radiation beam. Treatment plan modeling was conducted to simulate effects induced by Medtronic, Inc.-manufactured devices on therapeutic radiation beams. As a continuation of grant-supported research, we show that radial and transverse open beam profiles of a medical accelerator were altered when compared with profiles resulting when implantable pacemakers and cardioverter-defibrillators are placed directly in the beam. Results are markedly different between the 2 devices in the axial plane and the sagittal planes. Vast differences are also presented for the therapeutic beams at 6-MV and 18-MV x-ray energies. Maximum changes in percentage depth dose are observed for the implantable cardioverter-defibrillator as 9.3% at 6 MV and 10.1% at 18 MV, with worst distance to agreement of isodose lines at 2.3 cm and 1.3 cm, respectively. For the implantable pacemaker, the maximum changes in percentage depth dose were observed as 10.7% at 6 MV and 6.9% at 18 MV, with worst distance to agreement of isodose lines at 2.5 cm and 1.9 cm, respectively. No differences were discernible for the defibrillation leads and the pacing lead.

  6. Association of sleep-wake habits in older people with changes in output of circadian pacemaker

    NASA Technical Reports Server (NTRS)

    Czeisler, C. A.; Dumont, M.; Duffy, J. F.; Steinberg, J. D.; Richardson, G. S.; Brown, E. N.; Sanchez, R.; Rios, C. D.; Ronda, J. M.

    1992-01-01

    Many elderly people complain of disturbed sleep patterns but there is not evidence that the need to sleep decreases with age; it seems rather that the timing and consolidation of sleep change. We tried to find out whether there is a concurrent change in the output of the circadian pacemaker with age. The phase and amplitude of the pacemaker's output were assessed by continuous measurement of the core body temperature during 40 h of sustained wakefulness under constant behavioural and environmental conditions. 27 young men (18-31 years) were compared with 21 older people (65-85 years; 11 men, 10 women); all were healthy and without sleep complaints. The mean amplitude of the endogenous circadian temperature oscillation (ECA) was 40% greater in young men than in the older group. Older men had a lower mean temperature ECA than older women. The minimum of the endogenous phase of the circadian temperature oscillation (ECP) occurred 1 h 52 min earlier in the older than in the young group. Customary bedtimes and waketimes were also earlier in the older group, as was their daily alertness peak. There was a close correlation between habitual waketime and temperature ECP in young men, which may lose precision with age, especially among women. These findings provide evidence for systematic age-related changes in the output of the human circadian pacemaker. We suggest that these changes may underlie the common complaints of sleep disturbance among elderly people. These changes could reflect the observed age-related deterioration of the hypothalamic nuclei that drive mammalian circadian rhythms.

  7. Electrograms from the canine sinoatrial pacemaker recorded in vitro and in situ.

    PubMed

    Cramer, M; Hariman, R J; Boxer, R; Hoffman, B F

    1978-12-01

    We have identified extracell potential changes associated with the electrical activity of the canine sinoatrial pacemaker. Small nonpolarizable electrodes and low frequency high gain amplification were used to record unipolar electrograms from both the epicardial and the endocardial surfaces of the canine sinus node. Initially in vitro studies were performed so that transmembrane action potential changes could be recorded simultaneously with the extracell potentials. The sinus nodal electrogram showed two characteristic potentials when the electrode was in immediate proximity to pacemaking cells: (1) During phase 4 there was a steady slope of about -30 to -100 muv/sec, and (2) during the transition from phase 4 to phase 0 of the transmembrane action potential the slope of the electrogram increased smoothly to approximately -400 to -1,000 muv/sec. These potentials were followed by high frequency deflections as cells in the surrounding atrium depolarized. Tetrodotoxin (5 mg/liter) rendered the atrial muscle inexcitable and delayed and then abolished the high frequency activity in the sinus electrogram, which then appeared as a continuous smooth tracing similar to the sinus pacemaker action potential but reversed in polarity. We then recorded these small localized potentials from the in situ canine heart. Sinus nodal electrograms could be obtained from beating hearts with hand held probes on the epicardial surface and with conventional recording catheters on the endocardial surface. The results demonstrate that the canine sinus node gives rise to detectable and characteristic changes in extracell potential and suggest that similar potentials can be recorded from man to evaluate sinus nodal function. PMID:727145

  8. Molecular Basis of Cardiac Myxomas

    PubMed Central

    Singhal, Pooja; Luk, Adriana; Rao, Vivek; Butany, Jagdish

    2014-01-01

    Cardiac tumors are rare, and of these, primary cardiac tumors are even rarer. Metastatic cardiac tumors are about 100 times more common than the primary tumors. About 90% of primary cardiac tumors are benign, and of these the most common are cardiac myxomas. Approximately 12% of primary cardiac tumors are completely asymptomatic while others present with one or more signs and symptoms of the classical triad of hemodynamic changes due to intracardiac obstruction, embolism and nonspecific constitutional symptoms. Echocardiography is highly sensitive and specific in detecting cardiac tumors. Other helpful investigations are chest X-rays, magnetic resonance imaging and computerized tomography scan. Surgical excision is the treatment of choice for primary cardiac tumors and is usually associated with a good prognosis. This review article will focus on the general features of benign cardiac tumors with an emphasis on cardiac myxomas and their molecular basis. PMID:24447924

  9. Advanced cardiac life support in out-of-hospital cardiac arrest

    Microsoft Academic Search

    Ian G. Stiell; George A. Wells; B. Field

    2004-01-01

    background The Ontario Prehospital Advanced Life Support (OPALS) Study tested the incremental effect on the rate of survival after out-of-hospital cardiac arrest of adding a program of advanced life support to a program of rapid defibrillation. methods This multicenter, controlled clinical trial was conducted in 17 cities before and after ad- vanced-life-support programs were instituted and enrolled 5638 patients who

  10. Pacemaker lead extraction and recapture of venous access: technical problems arising from extensive venous obstruction.

    PubMed

    Kutarski, Andrzej; Pietura, Rados?aw; M?ynarczyk, Krzysztof; Ma?ecka, Barbara; G?owniak, Andrzej

    2012-01-01

    We report the case of the extraction of 18 year-old leads in a patient with a DDD pacemaker, and chronic obstruction of the left subclavian and innominate veins coexisting with extensive stenoses in the upper caval vein. After removal of pacing leads, angiographic guidewires were introduced via the Byrd dilatators and new pacing leads introduced with the use of long sheaths originally dedicated for transvenous left ventricular leads implantation. With this case, we discuss the problems arising during reimplantation of pacing leads in patients with chronic venous occlusion. PMID:23042316

  11. Corrosion and degradation of a polyurethane/Co-Ni-Cr-Mo pacemaker lead

    SciTech Connect

    Sung, P.; Fraker, A.C.

    1987-12-01

    An investigation to study changes in the metal surfaces and the polyurethane insulation of heart pacemaker leads under controlled in vitro conditions was conducted. A polyurethane (Pellethane 2363-80A)/Co-Ni-Cr-Mo (MP35N) wire lead was exposed in Hanks' physiological saline solution for 14 months and then analyzed using scanning electron microscopy, x-ray energy dispersive analysis, and small angle x-ray scattering. Results showed that some leakage of solution into the lead had occurred and changes were present on both the metal and the polyurethane surfaces.

  12. Corrosion and degradation of a polyurethane/Co-Ni-Cr-Mo pacemaker lead.

    PubMed

    Sung, P; Fraker, A C

    1987-12-01

    An investigation to study changes in the metal surfaces and the polyurethane insulation of heart pacemaker leads under controlled in vitro conditions was conducted. A polyurethane (Pellethane 2363-80A)/Co-Ni-Cr-Mo (MP35N) wire lead was exposed in Hanks' physiological saline solution for 14 months and then analyzed using scanning electron microscopy, x-ray energy dispersive analysis, and small angle x-ray scattering. Results showed that some leakage of solution into the lead had occurred and changes were present on both the metal and the polyurethane surfaces. PMID:3429467

  13. Recalls of Cardiac Implants in the Last Decade: What Lessons Can We Learn?

    PubMed Central

    Schaller, Sandra; Kolominsky-Rabas, Peter L.

    2015-01-01

    Background Due to an ageing population and demographic changes worldwide, a higher prevalence of heart disease is forecasted, which causes an even higher demand for cardiac implants in future. The increasing high incidence of clinical adverse events attributed especially to high-risk medical devices has led an advocated change from many stakeholders. This holds especially true for devices like cardiac implants, with their high-risk nature and high complication rates associated with considerable mortality, due to their frequent use in older populations with frequent co-morbidities. To ensure patients’ safety, the objective of this study is to analyze different cardiac implants recall reasons and different recall systems, based on an overview of the recalls of cardiac implant medical devices in the last decade. On the basis of the results from this structured analysis, this study provides recommendations on how to avoid such recalls from a manufacturer perspective, as well as how to timely react to an adverse event from a post-surveillance system perspective. Methods and Findings A systematic search of cardiac implant recalls information has been performed in the PubMed, ScienceDirect and Scopus databases, as well as data sources in regulatory authorities from 193 UN Member States. Data has been extracted for the years 2004-2014 with the following criteria applied: cardiac implant medical device recalls and reasons for recall, associated harm or risk to patients. From the data sources described above, eleven regulatory authorities and 103 recall reports have been included in this study. The largest cardiac implant categories include ICDs 40.8%, pacemakers 14.5% and stents 14.5%. Regarding the recall reasons, the majority of reports were related to device battery problems (33.0%) and incorrect therapy delivery (31.1%). From a total of 103 recall reports, five reported death and serious injuries. Our review highlights weaknesses in the current cardiac implant recall system, including data reporting and management issues and provides recommendations for the improvement of safety information and management. Conclusion Due to the mortality associated with the nature of cardiac implants, the traceability and transparency of safety hazards information is crucial. By a structured analysis of recall reasons and their efficient management, important knowledge is gained to inform an effective safety-reporting system for monitoring the safety of cardiac implanted patients, ideally by building up cardiac implant registries worldwide in the future. PMID:25962074

  14. Acute Beneficial Hemodynamic Effects of a Novel 3D-Echocardiographic Optimization Protocol in Cardiac Resynchronization Therapy

    PubMed Central

    Hauck, Simon; Lesevic, Hasema; Barthel, Petra; Michalk, Fabian; Hoppe, Katharina; Hausleiter, Jörg; Kolb, Christof

    2012-01-01

    Background Post-implantation therapies to optimize cardiac resynchronization therapy (CRT) focus on adjustments of the atrio-ventricular (AV) delay and ventricular-to-ventricular (VV) interval. However, there is little consensus on how to achieve best resynchronization with these parameters. The aim of this study was to examine a novel combination of doppler echocardiography (DE) and three-dimensional echocardiography (3DE) for individualized optimization of device based AV delays and VV intervals compared to empiric programming. Methods 25 recipients of CRT (male: 56%, mean age: 67 years) were included in this study. Ejection fraction (EF), the primary outcome parameter, and left ventricular (LV) dimensions were evaluated by 3DE before CRT (baseline), after AV delay optimization while pacing the ventricles simultaneously (empiric VV interval programming) and after individualized VV interval optimization. For AV delay optimization aortic velocity time integral (AoVTI) was examined in eight different AV delays, and the AV delay with the highest AoVTI was programmed. For individualized VV interval optimization 3DE full-volume datasets of the left ventricle were obtained and analyzed to derive a systolic dyssynchrony index (SDI), calculated from the dispersion of time to minimal regional volume for all 16 LV segments. Consecutively, SDI was evaluated in six different VV intervals (including LV or right ventricular preactivation), and the VV interval with the lowest SDI was programmed (individualized optimization). Results EF increased from baseline 23±7% to 30±8 (p<0.001) after AV delay optimization and to 32±8% (p<0.05) after individualized optimization with an associated decrease of end-systolic volume from a baseline of 138±60 ml to 115±42 ml (p<0.001). Moreover, individualized optimization significantly reduced SDI from a baseline of 14.3±5.5% to 6.1±2.6% (p<0.001). Conclusions Compared with empiric programming of biventricular pacemakers, individualized echocardiographic optimization with the integration of 3-dimensional indices into the optimization protocol acutely improved LV systolic function and decreased ESV and can be used to select the optimal AV delay and VV interval in CRT. PMID:22319598

  15. Cardiac muscle cells

    NSDL National Science Digital Library

    Nathanael Reveal (None; )

    2007-07-02

    Cardiac muscles are found only in the heart. They work together to bring deoxygenated blood in and push oxygenated blood out into the body. Essentially, they keep your heart pumping and your body alive.

  16. Serial lead impedance measurements confirm fixation of helical screw electrodes during pacemaker implantation.

    PubMed

    Roelke, M; Bernstein, A D; Parsonnet, V

    2000-04-01

    The purpose of this study was to determine whether serial measurements of helical screw pacemaker lead impedance could reliably confirm electrode fixation in the right atrium and right ventricle. Fixation is generally assessed fluoroscopically, which can be misleading because the myocardium is radiolucent. Alternatively, because the electrical conductivity of blood is greater than that of myocardium, serial measurements of the lead impedance might be expected to show an impedance increase with appropriate fixation of the pacemaker electrode when the electrode becomes embedded in myocardial tissue. Impedance measurements were made during the placement of 23 atrial and 28 ventricular active fixation electrodes in 31 consecutive patients. Impedance measurements were recorded in unipolar and bipolar electrode configurations with the electrode free floating in the chamber, unfixed (with exposed screws) but touching the endocardial surface, and after fixation. No significant impedance differences were found between free-floating and unfixed electrode positions. With fixation, the lead impedance increased significantly in the ventricle (P = 0.0001, unipolar and bipolar) and the atrium (P = 0.0069 unipolar and 0.0052 bipolar). Typical increases, reflected by median values, were 197 ohms unipolar and 203 ohms bipolar in the ventricle and 47 ohms unipolar and 53 ohms bipolar in the atrium for electrodes with permanently exposed or retractable screw designs. Comparing serial measurements of lead impedance before and after electrode fixation is a valid electrical method of confirming appropriate fixation of helical screw electrodes. PMID:10793439

  17. Membrane currents underlying delayed rectification and pace-maker activity in frog atrial muscle

    PubMed Central

    Brown, Hilary F.; Noble, Susan J.

    1969-01-01

    1. A double sucrose gap method has been used to polarize and voltage clamp frog atrial muscle strips. 2. In response to steady depolarizing currents, normally quiescent strips often show pace-maker activity, and long lasting depolarization occurs when the current is terminated. 3. Voltage clamp experiments reveal the presence of two current components underlying delayed rectification. 4. The first of these components has a time constant which varies with potential and is approximately 500 msec at -90 mV. Its reversal potential usually lies between -70 and -40 mV and has always been found to be positive to the resting potential of normally quiescent fibres. 5. The time constant of the second component is extremely slow (? [unk] 5 sec at -90 mV). Its reversal potential is much more positive than that of the faster component. 6. The results confirm the presence of a component of inward current which is insensitive to tetrodotoxin (TTX), having an activation threshold about 20 mV positive to the sodium threshold. This current differs from the two components underlying delayed rectification both in its greater speed of activation and in showing inactivation. The inactivation of this TTX-insensitive current is also a fairly rapid process. 7. It is suggested that pace-making in sino-atrial muscle may depend upon the deactivation of the faster component of delayed rectification and that the TTX-insensitive inward current is also involved. PMID:5824109

  18. [Infectious endocarditis on permanent endocavitary pacemakers: value of echocardiography and review of the literature].

    PubMed

    Kugener, H; Rey, J L; Tribouilloy, C; Hermida, J S; Jarry, G; Avinée, P; Maingourd, Y

    1993-06-01

    Infectious endocarditis around indwelling pacemakers is rare (0.15% of all implantations). They have a gloomy prognosis with a global mortality rate of nearly 34% as emerges from this review of the literature concerning 58 cases of infectious endocarditis published within the past 16 years. On the basis of the 6 cases which the authors report, they stress the importance and sometimes difficulty of using ultrasound in a positive diagnosis. Cardiographic ultrasound, which can determine the size and emboligenic nature of vegetations is capital in choosing how to remove the pacemakers. Percutaneous ablation by simply pulling or by catheterization currently gives the best results, but it may be necessary to resort to surgery involving right atriotomy if emboligenic vegetations are present. By combining antibiotic treatment and ablation of the intracavitary material, a cure is obtained in 92% of cases. These figures should be compared with the lack of success of using antibiotic treatment alone which results in a high level of mortality (84%). PMID:8363322

  19. Three-dimensional autonomous pacemaker in the photosensitive Belousov-Zhabotinsky medium

    NASA Astrophysics Data System (ADS)

    Azhand, A.; Totz, J. F.; Engel, H.

    2014-10-01

    In experiments with the photosensitive Belousov-Zhabotinsky reaction (PBZR) we found a stable three-dimensional organizing center that periodically emits trigger waves of chemical concentration. The experiments are performed in a parameter regime with negative line tension using an open gel reactor to maintain stationary non-equilibrium conditions. The observed periodic wave source is formed by a scroll ring stabilized due to its interaction with a no-flux boundary. Sufficiently far from the boundary, the scroll ring expands and undergoes the negative line tension instability before it finally develops into scroll wave turbulence. Our experimental results are reproduced by numerical integration of the modified Oregonator model for the PBZR. Stationary and breathing self-organized pacemakers have been found in these numerical simulations. In the latter case, both the radius of the scroll ring and the distance of its filament plane to the no-flux boundary after some transient undergo undamped stable limit cycle oscillations. So far, contrary to their stationary counterpart, the numerically predicted breathing autonomous pacemaker has not been observed in the chemical experiment.

  20. Explanted Pacemakers: Observations of the Long-term Foreign Body Response

    Microsoft Academic Search

    Lora Perry; Floyd Karp; Kip Hauch; Buddy D. Ratner

    Implanted cardiac pacing systems are widely used medical devices for the treatment of electrophysiological disorders. This study examines morphological and histological characteristics of the foreign body response observed in postmortem human subjects with long term implanted cardiac pacing devices. Four implanted pacing systems were retrieved from cadavers. Tissues were fixed, sectioned and stained with Hæmatoxylin and Eosin, Wright-Giemsa, and Masson's

  1. Direct Cardiac Reprogramming: Advances in Cardiac Regeneration

    PubMed Central

    Chen, Olivia; Qian, Li

    2015-01-01

    Heart disease is one of the lead causes of death worldwide. Many forms of heart disease, including myocardial infarction and pressure-loading cardiomyopathies, result in irreversible cardiomyocyte death. Activated fibroblasts respond to cardiac injury by forming scar tissue, but ultimately this response fails to restore cardiac function. Unfortunately, the human heart has little regenerative ability and long-term outcomes following acute coronary events often include chronic and end-stage heart failure. Building upon years of research aimed at restoring functional cardiomyocytes, recent advances have been made in the direct reprogramming of fibroblasts toward a cardiomyocyte cell fate both in vitro and in vivo. Several experiments show functional improvements in mouse models of myocardial infarction following in situ generation of cardiomyocyte-like cells from endogenous fibroblasts. Though many of these studies are in an early stage, this nascent technology holds promise for future applications in regenerative medicine. In this review, we discuss the history, progress, methods, challenges, and future directions of direct cardiac reprogramming.

  2. Computational modeling of anoctamin 1 calcium-activated chloride channels as pacemaker channels in interstitial cells of Cajal

    PubMed Central

    Gibbons, Simon J.; Farrugia, Gianrico; Sneyd, James; Cheng, Leo K.

    2014-01-01

    Interstitial cells of Cajal (ICC) act as pacemaker cells in the gastrointestinal tract by generating electrical slow waves to regulate rhythmic smooth muscle contractions. Intrinsic Ca2+ oscillations in ICC appear to produce the slow waves by activating pacemaker currents, currently thought to be carried by the Ca2+-activated Cl? channel anoctamin 1 (Ano1). In this article we present a novel model of small intestinal ICC pacemaker activity that incorporates store-operated Ca2+ entry and a new model of Ano1 current. A series of simulations were carried out with the ICC model to investigate current controversies about the reversal potential of the Ano1 Cl? current in ICC and to predict the characteristics of the other ion channels that are necessary to generate slow waves. The model results show that Ano1 is a plausible pacemaker channel when coupled to a store-operated Ca2+ channel but suggest that small cyclical depolarizations may still occur in ICC in Ano1 knockout mice. The results predict that voltage-dependent Ca2+ current is likely to be negligible during the slow wave plateau phase. The model shows that the Cl? equilibrium potential is an important modulator of slow wave morphology, highlighting the need for a better understanding of Cl? dynamics in ICC. PMID:24481603

  3. Symptomatic upper-extremity deep venous thrombosis after pacemaker placement in a pediatric patient: how to treat?

    PubMed

    Spar, David S; Anderson, Jeffrey B; Palumbo, Joseph S; Kukreja, Kamlesh U; Czosek, Richard J

    2013-06-01

    Symptomatic upper-extremity deep venous thrombosis (UEDVT) after pacemaker placement in adults has been reported, but the occurrence of UEDVT in pediatric patients is poorly defined, and no treatment guidelines exist. This report describes a 14-year old girl with a history of complete atrioventricular block who experienced a symptomatic UEDVT 8 months after placement of a transvenous pacemaker. The girl was treated initially with anticoagulation including subcutaneous enoxaparin and a heparin drip, which did not resolve the venous obstruction. In the interventional laboratory, a venogram demonstrated complete obstruction of the left subclavian vein, which was treated successfully with catheter-directed alteplase, direct thrombus removal by manual suctioning, and balloon angioplasty. Warfarin therapy was continued for an additional 6 months, with follow-up venous ultrasounds demonstrating left subclavian vein patency. Soon after completing warfarin therapy, the girl presented with minimal edema of her left distal extremity and was thought to have post-thrombotic syndrome, which resolved quickly. She continued to receive aspirin therapy, with no recurrence of symptoms. In conclusion, symptomatic UEDVT after pacemaker placement in a pediatric patient can be treated successfully with both anticoagulation and interventional therapies. Further studies are needed to evaluate the incidence of thrombus formation among children with transvenous pacemaker placement together with the development of guidelines based on the safety and effectiveness of differing treatments. PMID:22618585

  4. Do electrical stun guns (TASER-X26w) affect the functional integrity of implantable pacemakers and defibrillators?

    Microsoft Academic Search

    Dhanunjaya Lakkireddy; Atul Khasnis; Jennifer Antenacci; Kay Ryshcon; Mina K. Chung; Donald Wallick; William Kowalewski; Dimpi Patel; Hanka Mlcochova; Ashok Kondur; James Vacek; David Martin; Andrea Natale; Patrick Tchou

    Aims High voltage electric current can adversely affect pacemakers (PM) and implantable cardioverter- defibrillator (ICD). The standard shock from an electrical stun gun (TASER- X26w, TASER International, Scottsdale, AZ) consists of a 5-s long application of high voltage, low current pulses at 19 pulses per second. Its effect on the functional integrity of PM and ICDs is unknown. Methods and

  5. Self-Organized Pacemakers in a Coupled Reaction-Diffusion-Mechanics System A. V. Panfilov and R. H. Keldermann

    E-print Network

    Utrecht, Universiteit

    ], which in turn affects the spiral wave dynamics [6]. Furthermore, a ``chain reaction'' of spiral waveSelf-Organized Pacemakers in a Coupled Reaction-Diffusion-Mechanics System A. V. Panfilov and R. H of a coupled reaction-diffusion-mechanics system, we find that me- chanical deformation can induce automatic

  6. A model for determining the induced voltage at the terminals of a pacemaker exposed to a low frequency magnetic field.

    PubMed

    Andretzko, J P; Hedjiedj, A; Guendouz, L

    2008-09-01

    This paper presents a method for calculating induced voltage, in vitro, at the terminals of a unipolar pacemaker (PM) subjected to a low frequency magnetic field. We propose a theoretical model which has been experimentally verified by using a homogeneous phantom model placed at the centre of the source generating a homogeneous magnetic field. The levels of the magnetic field used in our experiment are in accordance with the European Directive 2004/40/EC, which sets the occupational electromagnetic field exposure limits. The voltage induced at the terminals of an implanted pacemaker results in the superimposition of two different voltage sources. The first is due to the presence of the loop formed by the PM system and the second is due to the induced currents circulating in the coupling medium. The influence of the induced currents, calculated by the impedance method, is weak compared to the voltage of the loop. The theoretical results obtained agree with the experimental value. Thus, the proposed model can be used to predict the behaviour of a pacemaker subjected to a low frequency magnetic field as well as to those fields within the accepted exposure limits for a patient with a pacemaker. PMID:18784392

  7. Involvement of actin microfilament in regulation of pacemaking activity increased by hypotonic stress in cultured ICCs of murine intestine.

    PubMed

    Wang, Z Y; Huang, X; Liu, D H; Lu, H L; Kim, Y C; Xu, W X

    2015-06-11

    Distension is a regular mechanical stimulus in gastrointestinal (GI) tract. This study was designed to investigate the effect of hypotonic stress on pacemaking activity and determine whether actin microfilament is involved in its mechanism in cultured murine intestinal interstitial cells of Cajal (ICCs) by using whole-cell patch-clamp and calcium imaging techniques. Hypotonic stress induced sustained inward holding current from the baseline to -650+/-110 pA and significantly decreased amplitudes of pacemaker current. Hypotonic stress increased the intensity of basal fluorescence ratio (F/F0) from baseline to 1.09+/-0.03 and significantly increased Ca(2+) oscillation amplitude. Cytochalasin-B (20 microM), a disruptor of actin microfilaments, significantly suppressed the amplitudes of pacemaker currents and calcium oscillations, respectively. Cytochalasin-B also blocked hypotonic stress-induced sustained inward holding current and hypotonic stress-induced increase of calcium oscillations. Phalloidin (20 microM), a stabilizer of actin microfilaments, significantly enhanced the amplitudes of pacemaker currents and calcium oscillations, respectively. Despite the presence of phalloidin, hypotonic stress was still able to induce an inward holding current and increased the basal fluorescence intensity. These results suggest that hypotonic stress induces sustained inward holding current via actin microfilaments and the process is mediated by alteration of intracellular basal calcium concentration and calcium oscillation in cultured intestinal ICCs. PMID:25536314

  8. Ambulatory Holter monitoring in asymptomatic patients with DDD pacemakers – do we need ACC/AHA Guidelines revision?

    PubMed Central

    Klimczak, Artur; Wranicz, Jerzy Krzysztof

    2013-01-01

    Introduction We sought to determine the usefulness of ambulatory 24-hour Holter monitoring in detecting asymptomatic pacemaker (PM) malfunction episodes in patients with dual-chamber pacemakers whose pacing and sensing parameters were proper, as seen in routine post-implantation follow-ups. Material and methods Ambulatory 24-hour Holter recordings (HM) were performed in 100 patients with DDD pacemakers 1 day after the implantation. Only asymptomatic patients with proper pacing and sensing parameters (assessed on PM telemetry on the first day post-implantation) were enrolled in the study. The following parameters were assessed: failure to pace, failure to sense (both oversensing and undersensing episodes) as well as the percentage of all PM disturbances. Results Despite proper sensing and pacing parameters, HM revealed PM disturbances in 23 patients out of 100 (23%). Atrial undersensing episodes were found in 12 patients (p < 0.005) with totally 963 episodes and failure to capture in 1 patient (1%). T wave oversensing was the most common ventricular channel disorder (1316 episodes in 9 patients, p < 0.0005). Malfunction episodes occurred sporadically, leading to pauses of up to 1.6 s or temporary bradycardia, which were, nevertheless, not accompanied by clinical symptoms. No ventricular pacing disturbances were found. Conclusions Asymptomatic pacemaker dysfunction may be observed in nearly 25% of patients with proper DDD parameters after implantation. Thus, ambulatory HM during the early post-implantation period may be a useful tool to detect the need to reprogram PM parameters. PMID:24273562

  9. Dynamical Mechanisms of Pacemaker Generation in IK1-Downregulated Human Ventricular Myocytes: Insights from Bifurcation Analyses of a Mathematical Model

    PubMed Central

    Kurata, Yasutaka; Hisatome, Ichiro; Matsuda, Hiroyuki; Shibamoto, Toshishige

    2005-01-01

    Dynamical mechanisms of the biological pacemaker (BP) generation in human ventricular myocytes were investigated by bifurcation analyses of a mathematical model. Equilibrium points (EPs), periodic orbits, stability of EPs, and bifurcation points were determined as functions of bifurcation parameters, such as the maximum conductance of inward-rectifier K+ current (IK1), for constructing bifurcation diagrams. Stable limit cycles (BP activity) abruptly appeared around an unstable EP via a saddle-node bifurcation when IK1 was suppressed by 84.6%. After the bifurcation at which a stable EP disappears, the IK1-reduced system has an unstable EP only, which is essentially important for stable pacemaking. To elucidate how individual sarcolemmal currents contribute to EP instability and BP generation, we further explored the bifurcation structures of the system during changes in L-type Ca2+ channel current (ICa,L), delayed-rectifier K+ currents (IK), or Na+/Ca2+ exchanger current (INaCa). Our results suggest that 1), ICa,L is, but IK or INaCa is not, responsible for EP instability as a requisite to stable BP generation; 2), IK is indispensable for robust pacemaking with large amplitude, high upstroke velocity, and stable frequency; and 3), INaCa is the dominant pacemaker current but is not necessarily required for the generation of spontaneous oscillations. PMID:16040746

  10. [Obesity and cardiac failure].

    PubMed

    Galinier, M; Pathak, A; Roncalli, J; Massabuau, P

    2005-01-01

    Obesity alone is the cause of 11% of cases of cardiac failure in men and 14% of cases in women in the United States. The frequency of obesity continues to rise in our country, 41% of our compatriots being obese or overweight. It is expected that obesity will become an important cause of cardiac failure in the coming years. The Framingham study showed that, after correction for other risk factors, for every point increase in body mass index, the increase in risk of developing cardiac failure was 5% in men and 7% in women. There are three physiopathological mechanisms to explain the adverse effects of obesity on left ventricular function: an increase in ventricular preload secondary to increased plasma volume induced by the high fatty mass; an increase in left ventricular afterload due to the common association of hypertension generated by activation of the sympathetic nervous system by hyperinsulinism; and systolic and diastolic dysfunction due to changes in the myocardial genome and coronary artery disease induced by risk factors of atherosclerosis aggravated by obesity. The adipocyte also secretes a number of hormones which act directly or indirectly on the myocardium: angiotensin II, leptin, resistin, adrenomedulin, cytokines. These haemodynamic and hormonal changes profoundly modify the genetic expression of the myocardium in obesity, favourising hypertrophy of the myocyte and the development of interstitial fibrosis. Whether it be eccentric in the absence of hypertension or concentric when hypertension is associated with obesity, left ventricular hypertrophy, although normalising left ventricular wall stress, has adverse consequences causing abnormal relaxation and decreased left ventricular compliance. Therefore, in obese patients, two forms of cardiac failure may be observed. The more common is due to diastolic dysfunction, obesity being one of the principal causes of cardiac failure with preserved systolic function. Cardiac failure due to systolic dysfunction is less common and may be observed in cases with inappropriate left ventricular hypertrophy which does not normalise abnormal left ventricular wall stress leading to cardiomyopathy, and in cases with associated coronary artery disease. Whatever the underlying mechanism, the diagnosis of cardiac failure is made more difficult by obesity. From the prognostic point of view, in the global population of patients with cardiac failure, obesity improves survival because it counteracts the adverse effect of cachexia; however, obesity increases the risk of sudden death. In fact, obesity is associated with dynamic change in QT interval. In cases of cardiac failure secondary to obesity-related cardiomyopathy, loss of weight leads to an improved functional status and a reduction of left ventricular remodelling and an increase of the ejection fraction. PMID:15724418

  11. Perspectives on Withdrawing Pacemaker and Implantable Cardioverter-Defibrillator Therapies at End of Life: Results of a Survey of Medical and Legal Professionals and Patients

    PubMed Central

    Kapa, Suraj; Mueller, Paul S.; Hayes, David L.; Asirvatham, Samuel J.

    2010-01-01

    OBJECTIVE: To determine the opinions of medical professionals, legal professionals, and patients regarding the withdrawal of implantable cardioverter-defibrillator (ICD) and pacemaker therapy at the end of life. PARTICIPANTS AND METHODS: A survey regarding 5 cases that focused on withdrawal of ICD or pacemaker therapy at the end of life was constructed and sent to 5270 medical professionals, legal professionals, and patients. The survey was administered from March 1, 2008, to March 1, 2009. RESULTS: Of the 5270 recipients of the survey, 658 (12%) responded. In a terminally ill patient requesting that his ICD be turned off, most legal professionals (90% [63/70]), medical professionals (98% [330/336]), and patients (85% [200/236]) agreed the ICD should be turned off. Most legal professionals (89%), medical professionals (87%), and patients (79%) also considered withdrawal of pacemaker therapy in a non–pacemaker-dependent patient appropriate. However, significantly more legal (81%) than medical professionals (58%; P<.001) or patients (68%, P=.02) agreed with turning off a pacemaker in the pacemaker-dependent patient. A similar number of legal professionals thought turning off a device was legal regardless of whether it was an ICD or pacemaker (45% vs 38%; P=.50). However, medical professionals were more likely to perceive turning off an ICD as legal than turning off a pacemaker (85% vs 41%; P<.001). CONCLUSION: Most respondents thought device therapy should be withdrawn if the patient requested its withdrawal at the end of life. However, opinions of medical professionals and patients tended to be dependent on the type of device, with turning off ICDs being perceived as more acceptable than turning off pacemakers, whereas legal professionals tended to perceive all devices as similar. Thus, education and discussion regarding managing devices at the end of life are important when having end-of-life discussions and making end-of-life decisions to better understand patients' perceptions and expectations. PMID:20843982

  12. Atrial Fibrosis Quantified Using Late Gadolinium Enhancement MRI is Associated With Sinus Node Dysfunction Requiring Pacemaker Implant

    PubMed Central

    Akoum, Nazem; Mcgann, Christopher; Vergara, Gaston; Badger, Troy; Ranjan, Ravi; Mahnkopf, Christian; Kholmovski, Eugene; Macleod, Rob; Marrouche, Nassir

    2015-01-01

    Introduction Sinus node dysfunction (SND) commonly manifests with atrial arrhythmias alternating with sinus pauses and sinus bradycardia. The underlying process is thought to be because of atrial fibrosis. We assessed the value of atrial fibrosis, quantified using Late Gadolinium Enhanced-MRI (LGE-MRI), in predicting significant SND requiring pacemaker implant. Methods Three hundred forty-four patients with atrial fibrillation (AF) presenting for catheter ablation underwent LGE-MRI. Left atrial (LA) fibrosis was quantified in all patients and right atrial (RA) fibrosis in 134 patients. All patients underwent catheter ablation with pulmonary vein isolation with posterior wall and septal debulking. Patients were followed prospectively for 329 ± 245 days. Ambulatory monitoring was instituted every 3 months. Symptomatic pauses and bradycardia were treated with pacemaker implantation per published guidelines. Results The average patient age was 65 ± 12 years. The average wall fibrosis was 16.7 ± 11.1% in the LA, and 5.3 ± 6.4% in the RA. RA fibrosis was correlated with LA fibrosis (R2 = 0.26; P < 0.01). Patients were divided into 4 stages of LA fibrosis (Utah I: <5%, Utah II: 5–20%, Utah III: 20–35%, Utah IV: >35%). Twenty-two patients (mean atrial fibrosis, 23.9%) required pacemaker implantation during follow-up. Univariate and multivariate analysis identified LA fibrosis stage (OR, 2.2) as a significant predictor for pacemaker implantation with an area under the curve of 0.704. Conclusions In patients with AF presenting for catheter ablation, LGE-MRI quantification of atrial fibrosis demonstrates preferential LA involvement. Significant atrial fibrosis is associated with clinically significant SND requiring pacemaker implantation. PMID:21806700

  13. [The evaluation of the adaptation of pupils starting instruction at 6 years old to new academic programs by using a computer analysis of cardiac variability].

    PubMed

    Semova, N; Manolova, A; Miteva, B

    1990-01-01

    Examination of the pulse variability of 6 years old (experimental group) and 7 years old control group schoolchildren is performed for establishing their adaptation capability to the educational process at the end of VI and VII class. 76 schoolchildren are comprised in the investigation. The analysis of the pulse variability is made on the basis of 10 min. ECG record on telemeter "Biomedica". A computer processing is made on the records by complex programmes for receiving indices related to the statistical characteristic of the dynamic order of cardiac intervals and to such giving their distribution. The receiving statistically significant differences for most of the indices between both groups of schoolchildren from VI class show an expressed activation of the adrenergic mechanisms with EG as well as higher "physiological value" of adaptation to the educational process. In VII the class the indices of the heart variability with EG practically show no differences from those of CG. This ascertainment proves, that at the age of 13 the potentialities for studies of those children starting school at 6 years are compensated with the children starting school at 7 years. This imposes the studies and the organization of the educative process for both 6 and 7 years old schoolchildren to be taken into consideration, to the completion of 7th class, with their age adaptive potentialities. PMID:2099449

  14. Drug Treatment of Cardiac Failure

    PubMed Central

    Achong, M. R.; Kumana, C. R.

    1982-01-01

    Treatment of cardiac failure should first be aimed at reversing or ameliorating the underlying pathological processes. This review highlights the common problems and pitfalls in the use of digoxin, diuretics and vasodilators in patients with cardiac failure. PMID:21289849

  15. Drug treatment of cardiac failure.

    PubMed

    Achong, M R; Kumana, C R

    1982-01-01

    Treatment of cardiac failure should first be aimed at reversing or ameliorating the underlying pathological processes. This review highlights the common problems and pitfalls in the use of digoxin, diuretics and vasodilators in patients with cardiac failure. PMID:21289849

  16. Sudden cardiac death.

    PubMed

    Kuriachan, Vikas P; Sumner, Glen L; Mitchell, L Brent

    2015-04-01

    Sudden death accounts for 300,000-400,000 deaths annually in the United States. Most sudden deaths are cardiac, and most sudden cardiac deaths are related to arrhythmias secondary to structural heart disease or primary electrical abnormalities of the heart. The most common structural disease leading to sudden death is ischemic heart disease. Nonischemic cardiomyopathy and other structural abnormalities such as arrhythmogenic ventricular dysplasia and hypertrophic cardiomyopathy may also be causative. Patients without structural disease have a primary electrical abnormality, such as long-QT syndrome or Brugada syndrome. Severe left ventricular systolic dysfunction is the main marker for sudden death in patients with ischemic or nonischemic cardiomyopathy. In other conditions, other markers for structural heart disease and electrical abnormalities need to be considered. It is seen that ?-blocker therapy is associated with a reduction in sudden cardiac death across a broad range of disorders. Nevertheless, the implantable cardioverter defibrillator remains the most effective treatment strategy in selected patients. PMID:25813838

  17. Primary cardiac tumors.

    PubMed Central

    Silverman, N A

    1980-01-01

    Cardiac tumors are a rare, but potentially curably form of heart disease. A high index of clinical suspicion is necessary for diagnosis as these tumors have protean manifestations that mimic a variety of other cardiac and noncardiac diseases. Presently, M-mode and two-dimensional echocardiography are utilized as safe, reliable, and noninvasive imaging modalities. Seventy-five per cent of these tumors are benign, with myxoma accounting for 50% and rhabodomyoma comprising 20% of lesions. Various histologic types of sarcoma are the predominant malignant cardiac neoplasms. With strict attention to avoiding perioperative tumor embolization, surgical resection of these lesions can be accomplished with minimal morbidity and mortality. Sixteen consecutive primary tumors of the heart have been surgically treated at Duke University Medical Center since 1966 with no perioperative deaths and no late recurrences. Images Figs. 2A and B. Fig. 3. Fig. 4. Figs. 5A and B Fig. 6. PMID:7362282

  18. Cardiac Device Therapy in Children

    Microsoft Academic Search

    George F. Van Hare

    It is ironic that the first transistorized, wearable pacemaker was designed by Earl Bakken specifically to make open heart\\u000a surgery in children possible (1). Despite their pediatric origins, however, current heart rhythm control devices and leads\\u000a are not designed or manufactured for children. Instead, they are designed with adults in mind, with respect to device size\\u000a and lead length, as

  19. Cardiac Response and Personality Organization

    ERIC Educational Resources Information Center

    Blatt, Sidney J.; Feirstein, Alan

    1977-01-01

    This study examines the level and variability of cardiac response during complex problem-solving and interposed rest periods and their differing relationships to estimates of personality integration on the Rorschach. Findings suggest cardiac variability may be a more differentiated measure than level of cardiac response. (Author)

  20. Cardiac Xenotransplantation: Future and Limitations

    Microsoft Academic Search

    Kiyoshi Ogata; Jeffrey L. Platt

    2004-01-01

    Despite improvements in pharmacological therapies, the outlook for patients with severe cardiac disease remains poor. At present, only transplantation can ‘cure’ end-stage cardiac failure. However, fewer than 5% of those who need a cardiac transplant receive one in the United States each year. To address this problem, some propose using animals as a source of organs for transplantation, that is,

  1. Thoracic epidural infusion with chloroprocaine for postoperative analgesia following epicardial pacemaker placement in an infant

    PubMed Central

    Kamata, Mineto; Corridore, Marco; Tobias, Joseph D

    2014-01-01

    In critically ill neonates and infants, major interventions, including thoracotomy, may result in significant postoperative respiratory insufficiency and pain leading to the need for postoperative mechanical ventilation. Although there are many potential options for providing postoperative analgesia, there continues to be expanding use of regional anesthesia in this population. One of the many reported advantages is the provision of postoperative analgesia while avoiding the deleterious effects on respiratory function that may be seen with systemic opioids. We report the use of thoracic epidural anesthesia using a continuous infusion of chloroprocaine to provide analgesia following thoracotomy and epicardial pacemaker placement in an infant. The perioperative plan was complicated by comorbid conditions including congenital complete heart block, recent rhinovirus infection with residual respiratory involvement, and prematurity. PMID:25364272

  2. Stability, precision, and near-24-hour period of the human circadian pacemaker

    NASA Technical Reports Server (NTRS)

    Czeisler, C. A.; Duffy, J. F.; Shanahan, T. L.; Brown, E. N.; Mitchell, J. F.; Rimmer, D. W.; Ronda, J. M.; Silva, E. J.; Allan, J. S.; Emens, J. S.; Dijk, D. J.; Kronauer, R. E.

    1999-01-01

    Regulation of circadian period in humans was thought to differ from that of other species, with the period of the activity rhythm reported to range from 13 to 65 hours (median 25.2 hours) and the period of the body temperature rhythm reported to average 25 hours in adulthood, and to shorten with age. However, those observations were based on studies of humans exposed to light levels sufficient to confound circadian period estimation. Precise estimation of the periods of the endogenous circadian rhythms of melatonin, core body temperature, and cortisol in healthy young and older individuals living in carefully controlled lighting conditions has now revealed that the intrinsic period of the human circadian pacemaker averages 24.18 hours in both age groups, with a tight distribution consistent with other species. These findings have important implications for understanding the pathophysiology of disrupted sleep in older people.

  3. [Superior vena cava syndrome induced by pacemaker probes, 12 years after introduction].

    PubMed

    Espitia, O; Guerin, P; Néel, A; Espitia-Thibault, A; Pottier, P; Planchon, B; Pistorius, M-A

    2013-05-01

    Superior vena cava syndrome is a rare disease, most often found to result from a malignant process, which causes extrinsic compression of the superior vena cava. In recent years, there has been an increase of superior vena cava syndrome related to medical devices (implantable site, pacemaker [PM], central venous line for parenteral nutrition...). We report the case of a 37-year-old patient who developed a superior vena cava syndrome 12 years after implantation of a PM. The diagnosis was established on venography after two negative venous-CT focused on the superior vena cava. The superior vena cava syndrome improved immediately after angioplasty and stenting covering the PM probes at the superior vena cava/brachiocephalic venous trunk junction. PMID:23433510

  4. Do pacemakers drive the central pattern generator for locomotion in mammals?

    PubMed

    Brocard, Frédéric; Tazerart, Sabrina; Vinay, Laurent

    2010-04-01

    Locomotor disorders profoundly impact quality of life of patients with spinal cord injury. Understanding the neuronal networks responsible for locomotion remains a major challenge for neuroscientists and a fundamental prerequisite to overcome motor deficits. Although neuronal circuitry governing swimming activities in lower vertebrates has been studied in great details, determinants of walking activities in mammals remain elusive. The manuscript reviews some of the principles relevant to the functional organization of the mammalian locomotor network and mainly focuses on mechanisms involved in rhythmogenesis. Based on recent publications supplemented with new experimental data, the authors will specifically discuss a new working hypothesis in which pacemakers, cells characterized by inherent oscillatory properties, might be functionally integrated in the locomotor network in mammals. PMID:20400712

  5. Circadian pacemakers in lizards: phase-response curves and effects of pinealectomy.

    PubMed

    Underwood, H

    1983-06-01

    Phase-response curves (PRCs) for 6-h fluorescent light pulses are described for both intact (sham-pinealectomized) and pinealectomized iguanid lizards (Sceloporus occidentalis). Although strongly diurnal in habit the PRC for intact lizards is more typical of those seen in nocturnal rodents. Other "nocturnal" characteristics of this lizard include the fact that the average free-running period (tau) is less than 24 h and the average tau in continuous light is longer than that observed in continuous darkness. The PRC for pinealectomized lizards is greatly distorted relative to that obtained from intact lizards. This "distortion" is discussed in terms of the role of the pineal as a coupling device or as a pacemaker within a multioscillator circadian system. In some individuals pinealectomy was also associated with 1) increased instability in free-running activity rhythms or arrhythmicity and 2) nocturnal entrainment to LD 12:12. PMID:6859292

  6. Usefulness of Hemodynamic Sensors for Physiologic Cardiac Pacing in Heart Failure Patients

    PubMed Central

    Occhetta, Eraldo; Bortnik, Miriam; Marino, Paolo

    2011-01-01

    The rate adaptive sensors applied to cardiac pacing should respond as promptly as the normal sinus node with an highly specific and sensitive detection of the need of increasing heart rate. Sensors operating alone may not provide optimal heart responsiveness: central venous pH sensing, variations in the oxygen content of mixed venous blood, QT interval, breathing rate and pulmonary minute ventilation monitored by thoracic impedance variations, activity sensors. Using sensors that have different attributes but that work in a complementary manners offers distinct advantages. However, complicated sensors interactions may occur. Hemodynamic sensors detect changes in the hemodynamic performances of the heart, which partially depends on the autonomic nervous system-induced inotropic regulation of myocardial fibers. Specific hemodynamic sensors have been designed to measure different expression of the cardiac contraction strength: Peak Endocardial Acceleration (PEA), Closed Loop Stimulation (CLS) and TransValvular Impedance (TVI), guided by intraventricular impedance variations. Rate-responsive pacing is just one of the potential applications of hemodynamic sensors in implantable pacemakers. Other issues discussed in the paper include: hemodynamic monitoring for the optimal programmation and follow up of patients with cardiac resynchronization therapy; hemodynamic deterioration impact of tachyarrhythmias; hemodynamic upper rate limit control; monitoring and prevention of vasovagal malignant syncopes. PMID:21461359

  7. Second degree AV block and severely impaired contractility in cardiac myxedema: a case report.

    PubMed

    Chatzitomaris, Apostolos; Scheeler, Michael; Gotzmann, Michael; Köditz, Roland; Schildroth, Janice; Knyhala, Kathy Miriam; Nicolas, Volkmar; Heyer, Christoph; Mügge, Andreas; Klein, Harald H; Dietrich, Johannes W

    2015-01-01

    The heart is a major target organ for thyroid hormone action. Severe overt hypothyroidism can result in diastolic hypertension, lowered cardiac output, impaired left ventricular contractility and diastolic relaxation, pericardial effusion and bradycardia. However, the function of the atrial pacemaker is usually normal and the degree by which the heart rate slows down is often modest. Here we report the case of a 20 year old male Caucasian with severe overt hypothyroidism. He presented with syncopation due to second degree atrioventricular block type Mobitz 2 and heart failure with reduced ejection fraction (38 %). Laboratory testing revealed a severe overt hypothyroidism with markedly elevated TSH (>100 mIU/L) and reduced fT3 and fT4 levels. The condition was caused by hypothyroid Graves' disease (Graves' disease with Hashimoto component). Although magnetic resonance imaging of the heart demonstrated decreased cardiac contractility and pericardial effusion, suggesting peri-myocarditis, plasma levels for BNP and troponin I were low. A possible infectious cause was unlikely, since testing for cardiotropic viruses was negative. The patient was treated with intravenous levothyroxine and after peripheral euthyroidism had been achieved, left ventricular ejection fraction returned to normal and pericardial effusion dissolved. Additionally, bradycardiac episodes abated, although intermittent second degree AV block was still occasionally present during the night. In conclusion, overt hypothyroidism may be associated by cardiac myxedema affecting both electrophysiology and contractility, observations that underscore the necessity of thyroid testing in different phenotypes of heart failure. PMID:26000037

  8. Cardiac memory during rather than after termination of left bundle branch block.

    PubMed

    Littmann, Laszlo; Proctor, Patrick A; Givens, Priscilla M

    2014-01-01

    An 83-year-old woman with chronic left bundle branch block and remote history of pacemaker implantation for intermittent AV block was hospitalized for fatigue and leg swelling. She had no cardiac complaints. Routine 12-lead electrocardiogram showed sinus rhythm with left bundle branch block. There were diffuse negative T waves in the inferior and anterolateral leads that were concordant with the QRS complexes. Echocardiogram was normal and nuclear perfusion heart scan showed no abnormality. It was noted that the negative T waves during left bundle branch block were in the exact same leads as were the deep negative QRS complexes during ventricular pacing. The electrocardiographic changes were consistent with cardiac memory. This case is unique because cardiac memory in patients with intermittent left bundle branch block typically occurs when the QRS complexes normalize and not during left bundle branch block itself. Our findings indicate that memory Ts can develop not only after normalization of wide complex rhythms but also with alternating wide complex rhythms as in the presented case where a ventricular paced rhythm was replaced by left bundle branch block. PMID:25172185

  9. Inhibitory effects of sevoflurane on pacemaking activity of sinoatrial node cells in guinea-pig heart

    PubMed Central

    Kojima, Akiko; Kitagawa, Hirotoshi; Omatsu-Kanbe, Mariko; Matsuura, Hiroshi; Nosaka, Shuichi

    2012-01-01

    BACKGROUND AND PURPOSE The volatile anaesthetic sevoflurane affects heart rate in clinical settings. The present study investigated the effect of sevoflurane on sinoatrial (SA) node automaticity and its underlying ionic mechanisms. EXPERIMENTAL APPROACH Spontaneous action potentials and four ionic currents fundamental for pacemaking, namely, the hyperpolarization-activated cation current (If), T-type and L-type Ca2+ currents (ICa,T and ICa,L, respectively), and slowly activating delayed rectifier K+ current (IKs), were recorded in isolated guinea-pig SA node cells using perforated and conventional whole-cell patch-clamp techniques. Heart rate in guinea-pigs was recorded ex vivo in Langendorff mode and in vivo during sevoflurane inhalation. KEY RESULTS In isolated SA node cells, sevoflurane (0.12–0.71 mM) reduced the firing rate of spontaneous action potentials and its electrical basis, diastolic depolarization rate, in a qualitatively similar concentration-dependent manner. Sevoflurane (0.44 mM) reduced spontaneous firing rate by approximately 25% and decreased If, ICa,T, ICa,L and IKs by 14.4, 31.3, 30.3 and 37.1%, respectively, without significantly affecting voltage dependence of current activation. The negative chronotropic effect of sevoflurane was partly reproduced by a computer simulation of SA node cell electrophysiology. Sevoflurane reduced heart rate in Langendorff-perfused hearts, but not in vivo during sevoflurane inhalation in guinea-pigs. CONCLUSIONS AND IMPLICATIONS Sevoflurane at clinically relevant concentrations slowed diastolic depolarization and thereby reduced pacemaking activity in SA node cells, at least partly due to its inhibitory effect on If, ICa,T and ICa,L. These findings provide an important electrophysiological basis of alterations in heart rate during sevoflurane anaesthesia in clinical settings. PMID:22356456

  10. Erbb2 Is Required for Cardiac Atrial Electrical Activity during Development

    PubMed Central

    Tenin, Gennadiy; Clowes, Christopher; Wolton, Kathryn; Krejci, Eliska; Wright, Jayne A.; Lovell, Simon C.; Sedmera, David; Hentges, Kathryn E.

    2014-01-01

    The heart is the first organ required to function during embryonic development and is absolutely necessary for embryo survival. Cardiac activity is dependent on both the sinoatrial node (SAN), which is the pacemaker of heart's electrical activity, and the cardiac conduction system which transduces the electrical signal though the heart tissue, leading to heart muscle contractions. Defects in the development of cardiac electrical function may lead to severe heart disorders. The Erbb2 (Epidermal Growth Factor Receptor 2) gene encodes a member of the EGF receptor family of receptor tyrosine kinases. The Erbb2 receptor lacks ligand-binding activity but forms heterodimers with other EGF receptors, stabilising their ligand binding and enhancing kinase-mediated activation of downstream signalling pathways. Erbb2 is absolutely necessary in normal embryonic development and homozygous mouse knock-out Erbb2 embryos die at embryonic day (E)10.5 due to severe cardiac defects. We have isolated a mouse line, l11Jus8, from a random chemical mutagenesis screen, which carries a hypomorphic missense mutation in the Erbb2 gene. Homozygous mutant embryos exhibit embryonic lethality by E12.5-13. The l11Jus8 mutants display cardiac haemorrhage and a failure of atrial function due to defects in atrial electrical signal propagation, leading to an atrial-specific conduction block, which does not affect ventricular conduction. The l11Jus8 mutant phenotype is distinct from those reported for Erbb2 knockout mouse mutants. Thus, the l11Jus8 mouse reveals a novel function of Erbb2 during atrial conduction system development, which when disrupted causes death at mid-gestation. PMID:25269082

  11. Multiple mechanisms of spiral wave breakup in a model of cardiac electrical activity

    NASA Astrophysics Data System (ADS)

    Fenton, Flavio H.; Cherry, Elizabeth M.; Hastings, Harold M.; Evans, Steven J.

    2002-09-01

    It has become widely accepted that the most dangerous cardiac arrhythmias are due to reentrant waves, i.e., electrical wave(s) that recirculate repeatedly throughout the tissue at a higher frequency than the waves produced by the heart's natural pacemaker (sinoatrial node). However, the complicated structure of cardiac tissue, as well as the complex ionic currents in the cell, have made it extremely difficult to pinpoint the detailed dynamics of these life-threatening reentrant arrhythmias. A simplified ionic model of the cardiac action potential (AP), which can be fitted to a wide variety of experimentally and numerically obtained mesoscopic characteristics of cardiac tissue such as AP shape and restitution of AP duration and conduction velocity, is used to explain many different mechanisms of spiral wave breakup which in principle can occur in cardiac tissue. Some, but not all, of these mechanisms have been observed before using other models; therefore, the purpose of this paper is to demonstrate them using just one framework model and to explain the different parameter regimes or physiological properties necessary for each mechanism (such as high or low excitability, corresponding to normal or ischemic tissue, spiral tip trajectory types, and tissue structures such as rotational anisotropy and periodic boundary conditions). Each mechanism is compared with data from other ionic models or experiments to illustrate that they are not model-specific phenomena. Movies showing all the breakup mechanisms are available at http://arrhythmia.hofstra.edu/breakup and at ftp://ftp.aip.org/epaps/chaos/E-CHAOEH-12-039203/ INDEX.html. The fact that many different breakup mechanisms exist has important implications for antiarrhythmic drug design and for comparisons of fibrillation experiments using different species, electromechanical uncoupling drugs, and initiation protocols.

  12. Distal balloon occlusion allows epicardial lead placement in a tortuous branch of the great cardiac vein.

    PubMed

    Patel, Parag; Banchs, Javier E; Stevenson, Robert T; Patel, Nehal D; Naccarelli, Gerald V; Wolbrette, Deborah L; Samii, Soraya M; Penny-Peterson, Erica D; Gonzalez, Mario D

    2009-08-01

    Cardiac resynchronization therapy (CRT) is a well established treatment modality in heart failure. Using standard techniques, placement of the left ventricular (LV) lead is usually successful; however LV lead placement failure remains a clinical problem. In the present report, the standard over-the-wire technique was not successful due to absence of the necessary support to place the lead into a tortuous vein. This was achieved using balloon occlusion of the great cardiac vein distal to the target vessel. An 81 year old female candidate for CRT presented for biventricular pacemaker implantation. After placement of the right ventricular lead, the CS was cannulated and an occlusive venogram was performed. A lateral branch was selected as the target vessel. Initial attempts at cannulating the vessel were unsuccessful due to the guidewire and telescoping delivery system prolapsing into the great cardiac vein. The acute angle prevented instrumentation of the branch with the tools available. A second parallel CS sheath was advanced to drive a balloon catheter used to occlude the great cardiac vein distal to the target vessel. This provided support for the guidewire and lead allowing their advancement through the tortuous vessel. Consecutive traction on the balloon during also helped to reflect the lead towards the vessel. The lead remained stable in its final position on the lateral wall of the LV with appropriate thresholds and no diaphragmatic stimulation. We report a case where balloon occlusion of the great cardiac vein distal to the target branch aided in advancing the LV lead into the desired position. This approach can be used in navigating lead placement to branches thought to be unreachable. Techniques such as this can decrease the failure rate of CRT implants. PMID:19184387

  13. The cardiac muscle cell

    Microsoft Academic Search

    Nicholas J. Severs

    2000-01-01

    Summary The cardiac myocyte is the most physically energetic cell in the body, contracting constantly, without tiring, 3 billion times or more in an average human lifespan. By coordinating its beating activity with that of its 3 billion neighbours in the main pump of the human heart, over 7,000 litres of blood are pumped per day, without con- scious effort,

  14. Cardiac and Pulmonary Injury

    Microsoft Academic Search

    George C. Velmahos; Muhammad U. Butt

    2008-01-01

    Cardiac and pulmonary injuries present major chal- lenges in diagnosis and treatment. Distinct differences between penetrating and blunt trauma of these or- gans exist. Outcomes for severe injuries are still grave. Organized trauma systems can provide optimal care by minimizing prehospital time, allowing easy access to imaging modalities, and offering state-of-the-art treatment strategies. A multidisciplinary approach, including surgeons, intensivists, and

  15. Cardiac Physiology of Pregnancy.

    PubMed

    May, Linda

    2015-07-01

    Although the physiology of the heart and vascular system has not changed, there are many things we have learned and are still learning today. Research related to heart adaptations during pregnancy has been performed since the 1930s. Since the mid-1950s, researchers began to look at changes in the maternal cardiovascular system during exercise while pregnant. Research related to exercise during pregnancy and offspring heart development began and has continued since the 1970s. We will review the normal female cardiovascular system adaptations to pregnancy in general. Additionally, topics related to maternal cardiac adaptations to pregnancy during acute exercise, as well as the chronic conditioning response from exercise training will be explored. Since physical activity during pregnancy influences fetal development, the fetal cardiac development will be discussed in regards to acute and chronic maternal exercise. Similarly, the influence of various types of maternal exercise on acute and chronic fetal heart responses will be described. Briefly, the topics related to how and if there is maternal-fetal synchrony will be explained. Lastly, the developmental changes of the fetal cardiovascular system that persist after birth will be explored. Overall, the article will discuss maternal cardiac physiology related to changes with normal pregnancy, and exercise during pregnancy, as well as fetal cardiac physiology related to changes with normal development, and exercise during pregnancy as well as developmental changes in offspring after birth. © 2015 American Physiological Society. Compr Physiol 5:1325-1344, 2015. PMID:26140720

  16. Hepato-cardiac disorders

    PubMed Central

    Fouad, Yasser Mahrous; Yehia, Reem

    2014-01-01

    Understanding the mutual relationship between the liver and the heart is important for both hepatologists and cardiologists. Hepato-cardiac diseases can be classified into heart diseases affecting the liver, liver diseases affecting the heart, and conditions affecting the heart and the liver at the same time. Differential diagnoses of liver injury are extremely important in a cardiologist’s clinical practice calling for collaboration between cardiologists and hepatologists due to the many other diseases that can affect the liver and mimic haemodynamic injury. Acute and chronic heart failure may lead to acute ischemic hepatitis or chronic congestive hepatopathy. Treatment in these cases should be directed to the primary heart disease. In patients with advanced liver disease, cirrhotic cardiomyopathy may develop including hemodynamic changes, diastolic and systolic dysfunctions, reduced cardiac performance and electrophysiological abnormalities. Cardiac evaluation is important for patients with liver diseases especially before and after liver transplantation. Liver transplantation may lead to the improvement of all cardiac changes and the reversal of cirrhotic cardiomyopathy. There are systemic diseases that may affect both the liver and the heart concomitantly including congenital, metabolic and inflammatory diseases as well as alcoholism. This review highlights these hepatocardiac diseases PMID:24653793

  17. Advanced Cardiac Life Support.

    ERIC Educational Resources Information Center

    Kirkwood Community Coll., Cedar Rapids, IA.

    This document contains materials for an advanced college course in cardiac life support developed for the State of Iowa. The course syllabus lists the course title, hours, number, description, prerequisites, learning activities, instructional units, required text, six references, evaluation criteria, course objectives by units, course…

  18. The Pathogenesis of Cardiac Fibrosis

    PubMed Central

    Kong, Ping; Christia, Panagiota; Frangogiannis, Nikolaos G

    2013-01-01

    Cardiac fibrosis is characterized by net accumulation of extracellular matrix proteins in the cardiac interstitium and contributes to both systolic and diastolic dysfunction in many cardiac pathophysiologic conditions. This review manuscript discusses the cellular effectors and molecular pathways implicated in the pathogenesis of cardiac fibrosis. Although activated myofibroblasts are the main effector cells in the fibrotic heart, monocytes/macrophages, lymphocytes, mast cells, vascular cells and cardiomyocytes may also contribute to the fibrotic response by secreting key fibrogenic mediators. Inflammatory cytokines and chemokines, reactive oxygen species, mast cell-derived proteases, endothelin-1, the renin/angiotensin/aldosterone system, matricellular proteins and growth factors (such as TGF-? and PDGF) are some of the best-studied mediators implicated in cardiac fibrosis. Both experimental and clinical evidence suggests that cardiac fibrotic alterations may be reversible. Understanding the mechanisms responsible for initiation, progression and resolution of cardiac fibrosis is crucial to design anti-fibrotic treatment strategies for patients with heart disease. PMID:23649149

  19. Genetics of sudden cardiac death.

    PubMed

    Bezzina, Connie R; Lahrouchi, Najim; Priori, Silvia G

    2015-06-01

    Sudden cardiac death occurs in a broad spectrum of cardiac pathologies and is an important cause of mortality in the general population. Genetic studies conducted during the past 20 years have markedly illuminated the genetic basis of the inherited cardiac disorders associated with sudden cardiac death. Here, we review the genetic basis of sudden cardiac death with a focus on the current knowledge on the genetics of the primary electric disorders caused primarily by mutations in genes encoding ion channels, and the cardiomyopathies, which have been attributed to mutations in genes encoding a broader category of proteins, including those of the sarcomere, the cytoskeleton, and desmosomes. We discuss the challenges currently faced in unraveling genetic factors that predispose to sudden cardiac death in the setting of sequela of coronary artery disease and present the genome-wide association studies conducted in recent years on electrocardiographic parameters, highlighting their potential in uncovering new biological insights into cardiac electric function. PMID:26044248

  20. A Home-Based Care Model of Cardiac Rehabilitation Using Digital Technology

    Microsoft Academic Search

    Mohanraj Karunanithi; Antti Sarela

    Cardiovascular disease (CVD) is the number one cause of death globally. There already exists a structured guideline to cardiac\\u000a rehabilitation for CVD patients as a means of preventing recurrence(s) of any cardiac events and return to an active, healthy\\u000a and satisfying lifestyle. Despite the availability of cardiac rehabilitation programs, utilisation among eligible patients\\u000a has been less than 20%. The barriers

  1. HCN Channels—Modulators of Cardiac and Neuronal Excitability

    PubMed Central

    Herrmann, Stefan; Schnorr, Sabine; Ludwig, Andreas

    2015-01-01

    Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels comprise a family of cation channels activated by hyperpolarized membrane potentials and stimulated by intracellular cyclic nucleotides. The four members of this family, HCN1–4, show distinct biophysical properties which are most evident in the kinetics of activation and deactivation, the sensitivity towards cyclic nucleotides and the modulation by tyrosine phosphorylation. The four isoforms are differentially expressed in various excitable tissues. This review will mainly focus on recent insights into the functional role of the channels apart from their classic role as pacemakers. The importance of HCN channels in the cardiac ventricle and ventricular hypertrophy will be discussed. In addition, their functional significance in the peripheral nervous system and nociception will be examined. The data, which are mainly derived from studies using transgenic mice, suggest that HCN channels contribute significantly to cellular excitability in these tissues. Remarkably, the impact of the channels is clearly more pronounced in pathophysiological states including ventricular hypertrophy as well as neural inflammation and neuropathy suggesting that HCN channels may constitute promising drug targets in the treatment of these conditions. This perspective as well as the current therapeutic use of HCN blockers will also be addressed. PMID:25580535

  2. The Physics of Cardiac Fibrillation: Strings that kill

    NASA Astrophysics Data System (ADS)

    Bodenschatz, Eberhard

    2009-03-01

    Fibrillation is a state of spatio-temporal chaos in a 3d-biological excitable medium, namely the heart muscle. The building blocks are wave-emitting three-dimensional topological singularities in the electric excitation field of the tissue. These string like singularities send out a rotating wave fields with very fast frequencies (up to 10 times normal heart rate) and thus dominate over the pacemaker. The incoherent electrical excitation of the spatio-temporal chaotic dynamics leads to an unsynchronized contraction of the cardiac muscle and to the loss of the pumping action, and if untreated to death. Due to the topological nature of the spatio-temporal chaotic state it is very difficult to control. Current defibrillation technologies use strong electric field pulses (1 kV, 30 A, 12 ms) to reset the whole muscle. Here we report that natural muscle heterogeneities act as wave emitting sites when a weak electric field pulse is applied across the tissue. We report theoretical predictions on the physics and support the findings by results from experiment. This work was conducted in collaboration with Stefan Luther (MPIDS), Falvio Fenton ( Cornell), Amgad Squires (Cornell), Robert Gilmour (Cornell), Valentin Krinsky (MPIDS), Alain Pumir (NIce).

  3. Critical appraisal of cardiac implantable electronic devices: complications and management

    PubMed Central

    Padeletti, Luigi; Mascioli, Giosuè; Perini, Alessandro Paoletti; Grifoni, Gino; Perrotta, Laura; Marchese, Procolo; Bontempi, Luca; Curnis, Antonio

    2011-01-01

    Population aging and broader indications for the implant of cardiac implantable electronic devices (CIEDs) are the main reasons for the continuous increase in the use of pacemakers (PMs), implantable cardioverter-defibrillators (ICDs) and devices for cardiac resynchronization therapy (CRT-P, CRT-D). The growing burden of comorbidities in CIED patients, the greater complexity of the devices, and the increased duration of procedures have led to an augmented risk of infections, which is out of proportion to the increase in implantation rate. CIED infections are an ominous condition, which often implies the necessity of hospitalization and carries an augmented risk of in-hospital death. Their clinical presentation may be either at pocket or at endocardial level, but they can also manifest themselves with lone bacteremia. The management of these infections requires the complete removal of the device and subsequent, specific, antibiotic therapy. CIED failures are monitored by competent public authorities, that require physicians to alert them to any failures, and that suggest the opportune strategies for their management. Although the replacement of all potentially affected devices is often suggested, common practice indicates the replacement of only a minority of devices, as close follow-up of the patients involved may be a safer strategy. Implantation of a PM or an ICD may cause problems in the patients’ psychosocial adaptation and quality of life, and may contribute to the development of affective disorders. Clinicians are usually unaware of the psychosocial impact of implanted PMs and ICDs. The main difference between PM and ICD patients is the latter’s dramatic experience of receiving a shock. Technological improvements and new clinical evidences may help reduce the total burden of shocks. A specific supporting team, providing psychosocial help, may contribute to improving patient quality of life. PMID:22915942

  4. Classification of cardiac arrhythmias using competitive networks.

    PubMed

    Leite, Cicilia R M; Martin, Daniel L; Sizilio, Glaucia R A; Dos Santos, Keylly E A; de Araujo, Bruno G; Valentim, Ricardo A M; Neto, Adriao D D; de Melo, Jorge D; Guerreiro, Ana M G

    2010-01-01

    Information generated by sensors that collect a patient's vital signals are continuous and unlimited data sequences. Traditionally, this information requires special equipment and programs to monitor them. These programs process and react to the continuous entry of data from different origins. Thus, the purpose of this study is to analyze the data produced by these biomedical devices, in this case the electrocardiogram (ECG). Processing uses a neural classifier, Kohonen competitive neural networks, detecting if the ECG shows any cardiac arrhythmia. In fact, it is possible to classify an ECG signal and thereby detect if it is exhibiting or not any alteration, according to normality. PMID:21096338

  5. EMI model of automatic implantable medical devices (AIMDs)

    Microsoft Academic Search

    Malik Mazhar Mahmood

    2008-01-01

    Due to increase of cardiac diseases, the use of Implantable Pacemakers has been increased which is an artificial source to provide the pacing pulse to heart. This therapy has improved the quality of thousands of people and in some cases provides the life sustaining therapy. Biotelemetry provides wireless communication links between implanted pacemaker and outside equipment for programming its pacing

  6. Phase resetting of the mammalian circadian clock relies on a rapid shift of a small population of pacemaker neurons.

    PubMed

    Rohling, Jos H T; vanderLeest, Henk Tjebbe; Michel, Stephan; Vansteensel, Mariska J; Meijer, Johanna H

    2011-01-01

    The circadian pacemaker of the suprachiasmatic nuclei (SCN) contains a major pacemaker for 24 h rhythms that is synchronized to the external light-dark cycle. In response to a shift in the external cycle, neurons of the SCN resynchronize with different pace. We performed electrical activity recordings of the SCN of rats in vitro following a 6 hour delay of the light-dark cycle and observed a bimodal electrical activity pattern with a shifted and an unshifted component. The shifted component was relatively narrow as compared to the unshifted component (2.2 h and 5.7 h, respectively). Curve fitting and simulations predicted that less than 30% of the neurons contribute to the shifted component and that their phase distribution is small. This prediction was confirmed by electrophysiological recordings of neuronal subpopulations. Only 25% of the neurons exhibited an immediate shift in the phase of the electrical activity rhythms, and the phases of the shifted subpopulations appeared significantly more synchronized as compared to the phases of the unshifted subpopulations (p<0.05). We also performed electrical activity recordings of the SCN following a 9 hour advance of the light-dark cycle. The phase advances induced a large desynchrony among the neurons, but consistent with the delays, only 19% of the neurons peaked at the mid of the new light phase. The data suggest that resetting of the central circadian pacemaker to both delays and advances is brought about by an initial shift of a relatively small group of neurons that becomes highly synchronized following a shift in the external cycle. The high degree of synchronization of the shifted neurons may add to the ability of this group to reset the pacemaker. The large desynchronization observed following advances may contribute to the relative difficulty of the circadian system to respond to advanced light cycles. PMID:21966529

  7. Two-oscillator structure of the pacemaker controlling the circadian rhythm of N-acetyltransferase in the rat pineal gland

    Microsoft Academic Search

    Helena Illnerová; Ji?í Van??ek

    1982-01-01

    1.The organization of the pacemaker driving the circadian rhythm of N-acetyltransferase activity in the rat pineal gland was studied by observing changes of the rhythm caused by 1 min light pulses applied at night. These pulses proved to be effective phase-shifting signals.2.After 1 min light pulses applied in the first half of the night. N-acetyltransferase activity began to increase anew

  8. Cardiac arrest in children

    PubMed Central

    Tress, Erika E; Kochanek, Patrick M; Saladino, Richard A; Manole, Mioara D

    2010-01-01

    Major advances in the field of pediatric cardiac arrest (CA) were made during the last decade, starting with the publication of pediatric Utstein guidelines, the 2005 recommendations by the International Liaison Committee on Resuscitation, and culminating in multicenter collaborations. The epidemiology and pathophysiology of in-hospital and out-of-hospital CA are now well described. Four phases of CA are described and the term “post-cardiac arrest syndrome” has been proposed, along with treatment goals for each of its four phases: immediate post-arrest, early post-arrest, intermediate and recovery phase. Hypothermia is recommended to be considered as a therapy for post-CA syndrome in comatose patients after CA, and large multicenter prospective studies are underway. We reviewed landmark articles related to pediatric CA published during the last decade. We present the current knowledge of epidemiology, pathophysiology and treatment of CA relevant to pre-hospital and acute care health practitioners. PMID:20930971

  9. Cardiac Resynchronization Therapy

    PubMed Central

    Owen, Joseph S.; Khatib, Sammy; Morin, Daniel P.

    2009-01-01

    Systolic heart failure is a major problem for Americans today, with 550,000 new cases diagnosed per year, and ultimately contributes to 287,000 deaths annually. While pharmacologic therapy has drastically improved outcomes in patients with systolic heart failure, hospitalizations from systolic heart failure continue to increase and remain a major cost burden. In response to this unmet need, recent years have seen dramatic improvements in device-based therapy targeting one cause of systolic dysfunction: dyssynchronous ventricular contraction. Cardiac resynchronization therapy aims to restore mechanical synchrony by electrically activating the heart in a synchronized manner. This review summarizes the rationale for cardiac resynchronization therapy, evidence for its use, current guidelines, and ongoing and future directions for research. PMID:21603451

  10. Cardiac muscle tissue engineering

    Microsoft Academic Search

    Maria Papadaki

    2003-01-01

    Cell-based therapy has emerged as a novel approach for replacing heart muscle, which is known not to regenerate after injury such as that caused by infarction or reconstructive surgery. Two types of cell-based therapies have been employed: injection of isolated cells or the implantation of in-vitro-grown cardiac muscle tissue equivalents In the first case, several cell types - including skeletal

  11. Cardiac Arrest in Pregnancy

    Microsoft Academic Search

    Alison A. Rodriguez; Gary A. Dildy

    Cardiac arrest (CA) in pregnancy is an uncommon occurrence with an incidence of about 1 in every 30,000 deliveries (1). The causes are quite numerous, but the management is essentially the same with the exception of a few modifications regarding\\u000a the fetus. In this chapter, causes of maternal mortality are reviewed along with potential interventions to decrease its incidence.\\u000a A

  12. Delirium After Cardiac Surgery

    Microsoft Academic Search

    James L. Rudolph

    \\u000a Delirium is an acute change in cognitive functioning, characterized by inattention and associated with disorganized thinking\\u000a or altered level of consciousness, which preferentially affects the older patients (Diagnostic and statistical manual of mental\\u000a disorders, fourth edition, text revision. Washington: American Psychiatric Association; 2000). After cardiac surgery, the\\u000a incidence of delirium has been reported between 2 and 73%, depending on the

  13. Inflammation and Cardiac Outcome

    PubMed Central

    Hohensinner, P.J.; Niessner, A.; Huber, K.; Weyand, C.M.; Wojta, J

    2015-01-01

    Purpose of Review Inflammation is a key component in cardiovascular disease. Controlling inflammatory events and their subsequent processes hold the potential for novel therapeutic options. Cytokines are the propagators of inflammation. In this review we will discuss important cytokines, including IL-6, TNF-alpha, MCP-1, M-CSF and GDF-15 and their effect on cardiac outcome. Recent findings IL-6 is a useful biomarker in patients with coronary artery disease. Summary PMID:21378564

  14. Hypothermic Cardiac Arrest

    Microsoft Academic Search

    Daniel F. Danzl

    The contemporary allure of hypothermia is regularly sparked by the apparent “reanimations” of profoundly cold patients in\\u000a prolonged cardiac arrest (CA). Recently, a physician who was resuscitated from 13.7°C presented her own case report at an\\u000a international conference (1). There are also promising ongoing investigations of mild therapeutic hypothermia for traumatic intracranial hypertension\\u000a and stroke (2–4). Nevertheless, hypothermia remains more

  15. Cardiac regenerative medicine.

    PubMed

    Yuasa, Shinsuke; Fukuda, Keiichi

    2008-01-01

    Severe heart failure is associated with damage to the myocardium that is irreversible with current medical therapies. Recent experimental and clinical studies, however, have opened the possibility of solving many of the associated problems, making this an exciting and tangible goal. There are many potential cell sources for regenerative cardiac medicine, including bone marrow stem cells, endothelial progenitor cells, skeletal myocytes, adult cardiac stem cells, and embryonic stem (ES) cells. Although ES cells are highly proliferative and suitable for mass production, they are not autologous, and an efficient protocol is yet to be established to ensure selective cardiomyocyte induction. Recent studies have successfully established inducible pluripotent stem (iPS) cells from mouse and human fibroblasts by the gene transfer of 4 transcription factors that are strongly expressed in ES cells: Oct3/4, Sox2, Klf4 and c-Myc. iPS cells can differentiate into all 3 germ layer-derived cells and are syngeneic, indicating that they can become an ideal cell source for regenerative medicine. Despite these successes, the accumulating evidence from fields as diverse as developmental biology, stem cell biology and tissue engineering must be integrated to achieve the full potential of cardiac regenerative medicine. PMID:18772528

  16. Sudden cardiac death and obesity.

    PubMed

    Plourde, Benoit; Sarrazin, Jean-François; Nault, Isabelle; Poirier, Paul

    2014-09-01

    For individuals and the society as a whole, the increased risk of sudden cardiac death in obese patients is becoming a major challenge, especially since obesity prevalence has been increasing steadily around the globe. Traditional risk factors and obesity often coexist. Hypertension, diabetes, obstructive sleep apnea and metabolic syndrome are well-known risk factors for CV disease and are often present in the obese patient. Although the bulk of evidence is circumstantial, sudden cardiac death and obesity share common traditional CV risk factors. Structural, functional and metabolic factors modulate and influence the risk of sudden cardiac death in the obese population. Other risk factors such as left ventricular hypertrophy, increased number of premature ventricular complexes, altered QT interval and reduced heart rate variability are all documented in both obese and sudden cardiac death populations. The present review focuses on out-of-hospital sudden cardiac death and potential mechanisms leading to sudden cardiac death in this population. PMID:25160995

  17. Cardiac Emergencies in Neurosurgical Patients

    PubMed Central

    Petropolis, Andrea; Cappellani, Ronald B.

    2015-01-01

    Perioperative safety concerns are a major area of interest in recent years. Severe cardiac perturbation such as cardiac arrest is one of the most dreaded complications in the intraoperative period; however, little is known about the management of these events in the patients undergoing elective neurosurgery. This special group needs further attention, as it is often neither feasible nor appropriate to apply conventional advanced cardiac life support algorithms in patients undergoing neurosurgery. Factors such as neurosurgical procedure and positioning can also have a significant effect on the occurrence of cardiac arrest. Therefore, the aim of this paper is to describe the various causes and management of cardiac emergencies with special reference to cardiac arrest during elective neurosurgical procedures, including discussion of position-related factors and resuscitative considerations in these situations. This will help to formulate possible guidelines for management of such events. PMID:25692145

  18. Sudden cardiac death – Historical perspectives

    PubMed Central

    Abhilash, S.P.; Namboodiri, Narayanan

    2014-01-01

    Sudden cardiac death (SCD) is an unexpected death due to cardiac causes that occurs in a short time period (generally within 1 h of symptom onset) in a person with known or unknown cardiac disease. It is believed to be involved in nearly a quarter of human deaths, with ventricular fibrillation being the most common mechanism. It is estimated that more than 7 million lives per year are lost to SCD worldwide. Historical perspectives of SCD are analyzed with a brief description on how the developments in the management of sudden cardiac arrest evolved over time. PMID:24568828

  19. Cardiac risk stratification and protection.

    PubMed

    Halub, Meghan E; Sidwell, Richard A

    2015-04-01

    The goal of preoperative cardiac evaluation is to screen for undiagnosed cardiac disease or to find evidence of known conditions that are poorly controlled to allow management that reduces the risk of perioperative cardiac complications. A careful history and physical examination combined with the procedure-specific risk is the cornerstone of this assessment. This article reviews a brief history of prior cardiac risk stratification indexes, explores current practice guidelines by the American College of Cardiology and the American Heart Association Task Force, reviews current methods for preoperative evaluation, discusses revascularization options, and evaluates perioperative medication recommendations. PMID:25814103

  20. Registry of Unexplained Cardiac Arrest

    ClinicalTrials.gov

    2015-04-13

    Cardiac Arrest; Long QT Syndrome; Brugada Syndrome; Catecholaminergi Polymorphic Ventricular Tachycardia; Idiopathic VentricularFibrillation; Early Repolarization Syndrome; Arrhythmogenic Right Ventricular Cardiomyopathy

  1. Usefulness of cardiac arrest centers?- extending lifesaving post-resuscitation therapies: the Arizona experience.

    PubMed

    Kern, Karl B

    2015-05-25

    The post-cardiac arrest syndrome is a complex, multisystems response to the global ischemia and reperfusion injury that occurs with the onset of cardiac arrest, its treatment (cardiopulmonary resuscitation) and the re-establishment of spontaneous circulation. Regionalization of post-cardiac arrest care, utilizing specified cardiac arrest centers (CACs), has been proposed as the best solution to providing optimal care for those successfully resuscitated after out-of-hospital cardiac arrest. A multidisciplinary team of intensive care specialists, including critical care/pulmonologists, cardiologists (general, interventional, and electrophysiology), neurologists, and physical medicine/rehabilitation experts, is crucial for such centers. Particular attention to the timely initiation of targeted temperature management and early coronary angiography/percutaneous coronary intervention is best provided by such CACs. A State-wide program of CACs was started in Arizona in 2007. This is a voluntary program, whereby medical centers agree to provide all resuscitated cardiac arrest patients brought to their facility with state-of-the-art post-resuscitation care, including targeted temperature management for comatose patients and strong consideration for emergent coronary angiography for all patients with a likely cardiac etiology for their cardiac arrest. Survival improved by more than 50% at facilities that became CACs with a commitment to provide aggressive post-resuscitation care to all such patients. Providing aggressive, post-resuscitation care is the next real opportunity to increase long-term survival for cardiac arrest patients. (Circ J 2015; 79: 1156-1163). PMID:25877829

  2. What to Expect during Cardiac Rehabilitation

    MedlinePLUS

    ... NHLBI on Twitter. What To Expect During Cardiac Rehabilitation During cardiac rehabilitation (rehab), you'll learn how to: Increase your ... Rate This Content: NEXT >> December 24, 2013 Cardiac Rehabilitation Clinical Trials Clinical trials are research studies that ...

  3. Correlates of objectively measured physical activity in cardiac patients.

    PubMed

    Byun, Wonwoo; Ozemek, Cemal; Riggin, Katrina; Strath, Scott; Kaminsky, Leonard

    2014-10-01

    Cardiac patients would benefit from increasing their physical activity (PA) levels. Understanding of factors that influence cardiac patients' PA participation would benefit the development of effective interventions. Therefore, the purpose of this study was to determine correlates of objectively-measured PA in cardiac patients. Participants were 65 cardiac patients (74% male, 95% white), age 58.6±10.6 years. The amount of time spent in PA was measured by ActiGraph GT3X accelerometers for 7 days prior to joining cardiac rehabilitation programs (CRP). A total of 25 potential determinants of PA across multiple domains (demographic, clinical, psychosocial, and behavioral) were measured via self-reported questionnaire and clinical examinations. Backward elimination model selection procedures were performed to examine associations of potential determinants with total PA (min/day) and moderate-to-vigorous PA (MVPA) (min/day). Patients spent 153.8±62.8 and 8.4±8.1 min/day in total PA and MVPA, respectively. Across four domains, ten and five potential correlates were found to be significant in univariate analyses for MVPA and total PA, respectively. In the final model, functional capacity, PA readiness, and participation in regular exercise were positively associated with MVPA (R(2) =26.6%). Functional capacity and PA readiness were also positively associated with total PA (R(2) =15.9%). Future initiatives to increase PA levels in cardiac patients could be improved by considering patients' functional capacity, PA readiness, and exercise history in designing interventions. PMID:25414828

  4. Correlates of objectively measured physical activity in cardiac patients

    PubMed Central

    Ozemek, Cemal; Riggin, Katrina; Strath, Scott; Kaminsky, Leonard

    2014-01-01

    Cardiac patients would benefit from increasing their physical activity (PA) levels. Understanding of factors that influence cardiac patients’ PA participation would benefit the development of effective interventions. Therefore, the purpose of this study was to determine correlates of objectively-measured PA in cardiac patients. Participants were 65 cardiac patients (74% male, 95% white), age 58.6±10.6 years. The amount of time spent in PA was measured by ActiGraph GT3X accelerometers for 7 days prior to joining cardiac rehabilitation programs (CRP). A total of 25 potential determinants of PA across multiple domains (demographic, clinical, psychosocial, and behavioral) were measured via self-reported questionnaire and clinical examinations. Backward elimination model selection procedures were performed to examine associations of potential determinants with total PA (min/day) and moderate-to-vigorous PA (MVPA) (min/day). Patients spent 153.8±62.8 and 8.4±8.1 min/day in total PA and MVPA, respectively. Across four domains, ten and five potential correlates were found to be significant in univariate analyses for MVPA and total PA, respectively. In the final model, functional capacity, PA readiness, and participation in regular exercise were positively associated with MVPA (R2 =26.6%). Functional capacity and PA readiness were also positively associated with total PA (R2 =15.9%). Future initiatives to increase PA levels in cardiac patients could be improved by considering patients’ functional capacity, PA readiness, and exercise history in designing interventions. PMID:25414828

  5. Electromagnetic immunity of implantable pacemakers exposed to wi-fi devices.

    PubMed

    Mattei, Eugenio; Censi, Federica; Triventi, Michele; Calcagnini, Giovanni

    2014-10-01

    The purpose of this study is to evaluate the potential for electromagnetic interference (EMI) and to assess the immunity level of implantable pacemakers (PM) when exposed to the radiofrequency (RF) field generated by Wi-Fi devices. Ten PM from five manufacturers, representative of what today is implanted in patients, have been tested in vitro and exposed to the signal generated by a Wi-Fi transmitter. An exposure setup that reproduces the actual IEEE 802.11b/g protocol has been designed and used during the tests. The system is able to amplify the Wi-Fi signal and transmits at power levels higher than those allowed by current international regulation. Such approach allows one to obtain, in case of no EMI, a safety margin for PM exposed to Wi-Fi signals, which otherwise cannot be derived if using commercial Wi-Fi equipment. The results of this study mitigate concerns about using Wi-Fi devices close to PM: none of the PM tested exhibit any degradation of their performance, even when exposed to RF field levels five times higher than those allowed by current international regulation (20 W EIRP). In conclusion, Wi-Fi devices do not pose risks of EMI to implantable PM. The immunity level of modern PM is much higher than the transmitting power of RF devices operating at 2.4 GHz. PMID:25162422

  6. Oxidant stress evoked by pacemaking in dopaminergic neurons is attenuated by DJ-1

    PubMed Central

    Guzman, Jaime N.; Sanchez-Padilla, Javier; Wokosin, David; Kondapalli, Jyothisri; Ilijic, Ema; Schumacker, Paul T.; Surmeier, D. James

    2015-01-01

    Parkinson's disease (PD) is a pervasive, aging-related neurodegenerative disease whose cardinal motor symptoms reflect the loss of a small group of neurons – dopaminergic neurons in the substantia nigra pars compacta (SNc)1. Mitochondrial oxidant stress is widely viewed as responsible for this loss2, but why these particular neurons should be stressed is a mystery. Using transgenic mice that expressed a redox-sensitive variant of green fluorescent protein targeted to the mitochondrial matrix, it was discovered that the unusual engagement of plasma membrane L-type calcium channels during normal autonomous pacemaking created an oxidant stress that was specific to vulnerable SNc dopaminergic neurons. This stress engaged defenses that induced transient, mild mitochondrial depolarization or uncoupling. The mild uncoupling was not affected by deletion of cyclophilin D, a component of the permeability transition pore, but was attenuated by genipin and purine nucleotides, antagonists of cloned uncoupling proteins. Knocking out DJ-1, a gene associated with an early onset form of PD, down-regulated the expression of two uncoupling proteins (UCP4, 5), compromised calcium-induced uncoupling and increased oxidation of matrix proteins specifically in SNc dopaminergic neurons. Because drugs approved for human use can antagonize calcium entry through L-type channels, these results point to a novel neuroprotective strategy for both idiopathic and familial forms of PD. PMID:21068725

  7. Clone mixtures and a pacemaker: new facets of Red-Queen theory and ecology.

    PubMed Central

    Sasaki, A; Hamilton, W D; Ubeda, F

    2002-01-01

    Host-parasite antagonistic interaction has been proposed as a potential agent to promote genetic polymorphism and to favour sex against asex, despite its twofold cost in reproduction. However, the host-parasite gene-for-gene dynamics often produce unstable cycles that tend to destroy genetic diversity. Here, we examine such diversity destroying coevolutionary dynamics of host and parasite, which is coupled through local or global migration, or both, between demes in a metapopulation structure. We show that, with global migration in the island model, peculiar out-of-phase islands spontaneously arise in the cluster of islands converging to a global synchrony. Such asynchrony induced by the 'pacemaker islands' serves to restore genetic variation. With increasing fraction of local migration, spots of asynchrony are converted into loci or foci of spiral and target patterns, whose rotating arms then cover the majority of demes. A multi-locus analogue of the model reproduces the same tendency toward asynchrony, and the condition arises for an advantage of asexual clones over their sexual counterpart when enough genetic diversity is maintained through metapopulation storage-migration serves as a cheap alternative to sex. PMID:11958707

  8. Melatonin marks circadian phase position and resets the endogenous circadian pacemaker in humans.

    PubMed

    Lewy, A J; Sack, R L; Blood, M L; Bauer, V K; Cutler, N L; Thomas, K H

    1995-01-01

    Measuring the dim light melatonin onset (DLMO) is a useful and practical way to assess circadian phase position in humans. As a marker for the phase and period of the endogenous circadian pacemaker, the DLMO has been shown to advance with exposure to bright light in the morning and to delay with exposure to bright light in the evening. This 'phase response curve' (PRC) to light has been applied in the treatment of winter depression, jet lag and shift work, as well as circadian phase sleep disorders. Exogenous melatonin has phase-shifting effects described by a PRC that is about 12 h out of phase with the PRC to light. That is, melatonin administration in the morning causes phase delays and in the afternoon causes phase advances. All of the circadian phase disorders that have been successfully treated with appropriately timed exposure to bright light can be treated with appropriately scheduled melatonin administration. Melatonin administration is more convenient and therefore may be the preferred treatment. PMID:7656692

  9. Epigenetic regulation of axonal growth of Drosophila pacemaker cells by histone acetyltransferase tip60 controls sleep.

    PubMed

    Pirooznia, Sheila K; Chiu, Kellie; Chan, May T; Zimmerman, John E; Elefant, Felice

    2012-12-01

    Tip60 is a histone acetyltransferase (HAT) enzyme that epigenetically regulates genes enriched for neuronal functions through interaction with the amyloid precursor protein (APP) intracellular domain. However, whether Tip60-mediated epigenetic dysregulation affects specific neuronal processes in vivo and contributes to neurodegeneration remains unclear. Here, we show that Tip60 HAT activity mediates axonal growth of the Drosophila pacemaker cells, termed "small ventrolateral neurons" (sLNvs), and their production of the neuropeptide pigment-dispersing factor (PDF) that functions to stabilize Drosophila sleep-wake cycles. Using genetic approaches, we show that loss of Tip60 HAT activity in the presence of the Alzheimer's disease-associated APP affects PDF expression and causes retraction of the sLNv synaptic arbor required for presynaptic release of PDF. Functional consequence of these effects is evidenced by disruption of the sleep-wake cycle in these flies. Notably, overexpression of Tip60 in conjunction with APP rescues these sleep-wake disturbances by inducing overelaboration of the sLNv synaptic terminals and increasing PDF levels, supporting a neuroprotective role for dTip60 in sLNv growth and function under APP-induced neurodegenerative conditions. Our findings reveal a novel mechanism for Tip60 mediated sleep-wake regulation via control of axonal growth and PDF levels within the sLNv-encompassing neural network and provide insight into epigenetic-based regulation of sleep disturbances observed in neurodegenerative diseases like Alzheimer's disease. PMID:22982579

  10. 76 FR 64223 - Cardiovascular Devices; Reclassification of External Pacemaker Pulse Generator Devices

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-17

    ...Food, Drug, and Cosmetic Act (the FD&C...consideration of risks involved with the...following cardiac surgery or a myocardial infarction...FD&C Act. V. Risks to Health After considering...Food, Drug, and Cosmetic Act and under...

  11. Antifibrinolytics in cardiac surgery.

    PubMed

    Dhir, Achal

    2013-01-01

    Cardiac surgery exerts a significant strain on the blood bank services and is a model example in which a multi-modal blood-conservation strategy is recommended. Significant bleeding during cardiac surgery, enough to cause re-exploration and/or blood transfusion, increases morbidity and mortality. Hyper-fibrinolysis is one of the important contributors to increased bleeding. This knowledge has led to the use of anti-fibrinolytic agents especially in procedures performed under cardiopulmonary bypass. Nothing has been more controversial in recent times than the aprotinin controversy. Since the withdrawal of aprotinin from the world market, the choice of antifibrinolytic agents has been limited to lysine analogues either tranexamic acid (TA) or epsilon amino caproic acid (EACA). While proponents of aprotinin still argue against its non-availability. Health Canada has approved its use, albeit under very strict regulations. Antifibrinolytic agents are not without side effects and act like double-edged swords, the stronger the anti-fibrinolytic activity, the more serious the side effects. Aprotinin is the strongest in reducing blood loss, blood transfusion, and possibly, return to the operating room after cardiac surgery. EACA is the least effective, while TA is somewhere in between. Additionally, aprotinin has been implicated in increased mortality and maximum side effects. TA has been shown to increase seizure activity, whereas, EACA seems to have the least side effects. Apparently, these agents do not differentiate between pathological and physiological fibrinolysis and prevent all forms of fibrinolysis leading to possible thrombotic side effects. It would seem prudent to select the right agent knowing its risk-benefit profile for a given patient, under the given circumstances. PMID:23545866

  12. Cardiac tamponade in Taiwan.

    PubMed

    Wang, M L; Liao, W B; Bullard, M J; Lin, F C; Lin, P J; Chiang, C W; Liaw, S J; Chiang, C H

    1997-09-01

    We retrospectively reviewed all of the patients who were treated for cardiac tamponade at Linkou Chang Gung Memorial Hospital between January 1991 and December 1995. There were a total of 112 patients (57 males, 55 females) with a mean age of 51 +/- 14 years (53 +/- 15, 49 +/- 13, respectively). Dyspnea was the most common complaint (85%). The mean blood pressure was 129 +/- 24/78 +/- 17 mmHg, and only 8% had a systolic blood pressure of less than 90 mmHg. Sinus tachycardia was the most frequent electrocardiographic finding (72%, 62/86). Diffuse low voltage was noted in 35% (30/86) of the patients and electrical alternans was seen in 17% (15/86). The mean volume of pericardial effusion was 610 +/- 263 ml. Sixty-five percent of the pericardial effusions were bloody, 31% were serosanguineous, 2% were purulent and 2% were chylous. Overall, 54.5% of the patients had malignant diseases. Of the 61 patients who died, 79% had malignancies. Thirty-five (57%) of these 48 patients had lung cancer. The mean survival time from emergent pericardiocentesis was 3.4 months. In conclusion, non-traumatic cardiac tamponade had a poor prognosis because most patients had malignant etiologies. There is still no definitive treatment for recurrent malignant pericardial effusion-induced cardiac tamponade. Percutaneous pericardiocentesis as clinically required may be the most appropriate treatment, since it is questionable whether such subjects should be subjected to the unnecessary pain and suffering associated with an operative procedure, considering their short mean survival time. PMID:9293407

  13. Genetic determinants of cardiac hypertrophy

    PubMed Central

    Marian, Ali J.

    2009-01-01

    Purpose of review Cardiac hypertrophy is a common phenotypic response of the heart to stimulants. It is associated with increased morbidity and mortality in various cardiovascular disorders. Genetic factors are important determinants of phenotypic expression of cardiac hypertrophy, whether in single-gene disorders or in complex traits. We focus on the molecular genetics of cardiac hypertrophy in various conditions with an emphasis on hypertrophic cardiomyopathy, a genetic paradigm of cardiac hypertrophic response. Recent findings The molecular genetic basis of cardiac hypertrophy in single-gene disorders has been partially elucidated. Likewise, the impact of genetics on the expression of cardiac hypertrophy in the general population has been demonstrated. Identification of mutations in the Z disk proteins has expanded the spectrum of causal mutations beyond the thin and thick filaments of the sarcomeres. In addition, modifier loci have been mapped and shown to impart considerable effects on the expression of cardiac hypertrophy in hypertrophic cardiomyopathy. Elucidation of the molecular genetics of sarcomeric hypertrophic cardiomyopathy and many of the phenocopies has highlighted the limitations of clinical diagnosis as a determinant of management and prognostic advice. The findings have raised the importance of diagnosis and treatment algorithms, which are based on both genotype and phenotype information. Summary Cardiac hypertrophy, regardless of the cause, is the phenotypic consequence of complex interactions between genetic and nongenetic factors. PMID:18382207

  14. Health Instruction Packages: Cardiac Anatomy.

    ERIC Educational Resources Information Center

    Phillips, Gwen; And Others

    Text, illustrations, and exercises are utilized in these five learning modules to instruct nurses, students, and other health care professionals in cardiac anatomy and functions and in fundamental electrocardiographic techniques. The first module, "Cardiac Anatomy and Physiology: A Review" by Gwen Phillips, teaches the learner to draw and label…

  15. The Chemotherapy of Cardiac Arrest

    PubMed Central

    Minuck, Max

    1965-01-01

    Direct-air ventilation, external cardiac compression, and external defibrillation are established techniques for patients who unexpectedly develop cardiac arrest. The proper use of drugs can increase the incidence of successful resuscitation. Intracardiac adrenaline (epinephrine) acts as a powerful stimulant during cardiac standstill and, in addition, converts fine ventricular fibrillation to a coarser type, more responsive to electrical defibrillation. Routine use of intravenous sodium bicarbonate is recommended to combat the severe metabolic acidosis accompanying cardiac arrest. Lidocaine is particularly useful when ventricular fibrillation or ventricular tachycardia tends to recur. Analeptics are contraindicated, since they invariably increase oxygen requirements of already hypoxic cerebral tissues. The following acrostic is a useful mnemonic for recalling the details of the management of cardiac arrest in their proper order: A (Airway), B (Breathing), C (Circulation), D (Diagnosis of underlying cause), E (Epinephrine), F (Fibrillation), G (Glucose intravenously), pH (Sodium bicarbonate), I (Intensive care). ImagesFig. 1Fig. 3Fig. 4 PMID:14216141

  16. ECG Monitoring in Cardiac Rehabilitation: Is It Needed?

    ERIC Educational Resources Information Center

    Greenland, Philip; Pomilla, Paul V.

    1989-01-01

    Discusses the controversial use of continuous electrocardiogram (ECG) monitoring as a safety measure in cardiac rehabilitation exercise programs. Little evidence substantiates its value for all patients during exercise. In the absence of empirical evidence documenting the worth of this expensive procedure, it is recommended for use with high-risk…

  17. Best Practices for Counseling in Cardiac Rehabilitation Settings

    ERIC Educational Resources Information Center

    Sheikh, Alia I.; Marotta, Sylvia A.

    2008-01-01

    Heart disease is the leading cause of death in the United States and can affect individuals of all ages, gender, ethnicity, and socioeconomic status. This article reviews the research on psychosocial interventions in cardiac rehabilitation programs and discusses the evolving set of best practices for counselors working in a new setting with people…

  18. Multipotent embryonic isl1+ progenitor cells lead to cardiac, smooth muscle, and endothelial cell diversification.

    PubMed

    Moretti, Alessandra; Caron, Leslie; Nakano, Atsushi; Lam, Jason T; Bernshausen, Alexandra; Chen, Yinhong; Qyang, Yibing; Bu, Lei; Sasaki, Mika; Martin-Puig, Silvia; Sun, Yunfu; Evans, Sylvia M; Laugwitz, Karl-Ludwig; Chien, Kenneth R

    2006-12-15

    Cardiogenesis requires the generation of endothelial, cardiac, and smooth muscle cells, thought to arise from distinct embryonic precursors. We use genetic fate-mapping studies to document that isl1(+) precursors from the second heart field can generate each of these diverse cardiovascular cell types in vivo. Utilizing embryonic stem (ES) cells, we clonally amplified a cellular hierarchy of isl1(+) cardiovascular progenitors, which resemble the developmental precursors in the embryonic heart. The transcriptional signature of isl1(+)/Nkx2.5(+)/flk1(+) defines a multipotent cardiovascular progenitor, which can give rise to cells of all three lineages. These studies document a developmental paradigm for cardiogenesis, where muscle and endothelial lineage diversification arises from a single cell-level decision of a multipotent isl1(+) cardiovascular progenitor cell (MICP). The discovery of ES cell-derived MICPs suggests a strategy for cardiovascular tissue regeneration via their isolation, renewal, and directed differentiation into specific mature cardiac, pacemaker, smooth muscle, and endothelial cell types. PMID:17123592

  19. Cardiac Remodeling in Obesity

    PubMed Central

    ABEL, E. DALE; LITWIN, SHELDON E.; SWEENEY, GARY

    2010-01-01

    The dramatic increase in the prevalence of obesity and its strong association with cardiovascular disease have resulted in unprecedented interest in understanding the effects of obesity on the cardiovascular system. A consistent, but puzzling clinical observation is that obesity confers an increased susceptibility to the development of cardiac disease, while at the same time affording protection against subsequent mortality (termed the obesity paradox). In this review we focus on evidence available from human and animal model studies and summarize the ways in which obesity can influence structure and function of the heart. We also review current hypotheses regarding mechanisms linking obesity and various aspects of cardiac remodeling. There is currently great interest in the role of adipokines, factors secreted from adipose tissue, and their role in the numerous cardiovascular complications of obesity. Here we focus on the role of leptin and the emerging promise of adiponectin as a cardioprotective agent. The challenge of understanding the association between obesity and heart failure is complicated by the multifaceted interplay between various hemodynamic, metabolic, and other physiological factors that ultimately impact the myocardium. Furthermore, the end result of obesity-associated changes in the myocardial structure and function may vary at distinct stages in the progression of remodeling, may depend on the individual pathophysiology of heart failure, and may even remain undetected for decades before clinical manifestation. Here we summarize our current knowledge of this complex yet intriguing topic. PMID:18391168

  20. 40 years of cardiac rehabilitation and secondary prevention in post-cardiac ischaemic patients. Are we still in the wilderness?

    PubMed

    Jelinek, Michael V; Thompson, David R; Ski, Chantal; Bunker, Stephen; Vale, Margarite J

    2015-01-20

    Cardiac rehabilitation (CR) is the sum of interventions required to ensure the best physical, psychological and social conditions so that patients with cardiac disease may assume their place in society and slow the progression of the disease. Exercise testing (ET) early after MI has been shown to result in earlier return to work than the non-performance of ET. Research quality CR has resulted in lower cardiovascular mortality and lower recurrent hospitalisation and has been shown to be cost-effective. However, the content of cardiac rehabilitation programmes varies considerably. The only randomised trial of CR as usually performed in the 'real world' showed that CR had no impact on cardiac death rates or any other outcome. Only 20-50% of eligible patients attend CR programmes and attendance at CR has not improved in the last 20 years despite major attempts to increase participation in CR. Alternative methods for provision of CR have been sought. These include home-based CR, case management approaches, and nurse coordinated prevention programmes. Telephone based programmes, such as The COACH Program, have been introduced to coach patients and improve behavioural and biomedical risk factors. These have been shown to improve risk factors better than usual patient care and to reduce recurrences of cardiac events after discharge from hospital due to MI. Expansion of novel approaches such as The COACH Program may help to counteract the non-attendance at CR. PMID:25464436

  1. Moderate physical exercise increases cardiac autonomic nervous system activity in children with low heart rate variability

    Microsoft Academic Search

    Narumi Nagai; Taku Hamada; Tetsuya Kimura; Toshio Moritani

    2004-01-01

    Object Our objective was to investigate the effect of a long-term moderate exercise program on cardiac autonomic nervous system (ANS) activity in healthy children. Methods Three hundred and five children aged 6–11 years participated in a 12-month school-based exercise training program (130–140 bpm, 20 min\\/day, 5 days\\/week). Cardiac ANS activities were measured using heart rate variability (HRV) power spectral analysis in resting conditions. Following

  2. Mandatory CPR training for students may improve cardiac-arrest survival rate, MDs say.

    PubMed Central

    Lyttle, J

    1996-01-01

    A mandatory cardiopulmonary resuscitation (CPR) program that started as a pilot project in Ottawa-area high schools is expanding to other Canadian schools. Besides CPR techniques, Grade 9 students are being taught about healthy lifestyles and how to recognize cardiac arrest. Emergency physician Justin Maloney, the program's principal architect, believes that in a decade this mandatory training will translate into increased bystander-initiated CPR and improved chances of survival for victims of cardiac arrest. Images p1173-a PMID:8873645

  3. Cardiac Surgery in Germany during 2014: A Report on Behalf of the German Society for Thoracic and Cardiovascular Surgery.

    PubMed

    Beckmann, Andreas; Funkat, Anne-Kathrin; Lewandowski, Jana; Frie, Michael; Ernst, Markus; Hekmat, Khosro; Schiller, Wolfgang; Gummert, Jan F; Cremer, Joachim Thomas

    2015-06-01

    Based on a voluntary registry of the German Society for Thoracic and Cardiovascular Surgery (GSTCVS), data of all heart surgery procedures performed in 78 German cardiac surgical units during the year 2014 are presented. In 2014, a total of 100,398 cardiac surgical procedures (implantable cardioverter-defibrillator and pacemaker procedures excluded) were submitted to the registry. More than 14.2% of the patients were older than 80 years, describing an increase of 0.4% compared with the previous year. The unadjusted in-hospital mortality for 40,006 isolated coronary artery bypass grafting procedures (84.7% on-pump, 15.3% off-pump) was 2.6%. In 31,359 isolated valve procedures (including 9,194 catheter-based procedures), an in-hospital mortality of 4.4% was observed. This annual updated registry of the GSTCVS is published since 1989. It is an important tool for quality assurance and voluntary public reporting by illustrating current standards and actual developments for nearly all cardiac surgical procedures in Germany. PMID:26011675

  4. Responsiveness of Health-Related Quality of Life Outcome Measures in Cardiac Rehabilitation: Comparison of Cardiac Rehabilitation Outcome Measures

    ERIC Educational Resources Information Center

    Hevey, David; McGee, Hannah M.; Horgan, John

    2004-01-01

    Assessment instruments that are not responsive to change are unsuitable as outcome tools in cardiac rehabilitation because they underestimate the psychosocial benefits of program attendance. Nine questionnaires were assessed for responsiveness with the standardized response mean (SRM). Questionnaires were allocated into 3 batteries, and each…

  5. Community-Based Responses to Impending or Actual Cardiac Arrest and Advances in Post-Cardiac Arrest Care

    Microsoft Academic Search

    Robert J. Myerburg; Mauricio Velez; Jeffrey Fenster; Donald G. Rosenberg; Agustin Castellanos

    2003-01-01

    Out-of-hospital cardiac arrest remains a major epidemiologic, clinical, scientific, and public health challenge. Emergency rescue systems (EMS) based in fire departments initially demonstrated encouraging outcomes as new strategies were developed in communities led by people committed to such programs, but the overall impact on survival has been modest. With improvement in automated external defibrillator (AED) technology in recent years, there

  6. Cardiac Nonmyocytes in the Hub of Cardiac Hypertrophy.

    PubMed

    Kamo, Takehiro; Akazawa, Hiroshi; Komuro, Issei

    2015-06-19

    Cardiac hypertrophy is characterized by complex multicellular alterations, such as cardiomyocyte growth, angiogenesis, fibrosis, and inflammation. The heart consists of myocytes and nonmyocytes, such as fibroblasts, vascular cells, and blood cells, and these cells communicate with each other directly or indirectly via a variety of autocrine or paracrine mediators. Accumulating evidence has suggested that nonmyocytes actively participate in the development of cardiac hypertrophy. In this review, recent progress in our understanding of the importance of nonmyocytes as a hub for induction of cardiac hypertrophy is summarized with an emphasis of the contribution of noncontact communication mediated by diffusible factors between cardiomyocytes and nonmyocytes in the heart. PMID:26089366

  7. Computational Reconstruction of Pacemaking and Intrinsic Electroresponsiveness in Cerebellar Golgi Cells

    PubMed Central

    Solinas, Sergio; Forti, Lia; Cesana, Elisabetta; Mapelli, Jonathan; De Schutter, Erik; D'Angelo, Egidio

    2007-01-01

    The Golgi cells have been recently shown to beat regularly in vitro (Forti et al., 2006. J. Physiol. 574, 711–729). Four main currents were shown to be involved, namely a persistent sodium current (I Na-p), an h current (I h), an SK-type calcium-dependent potassium current (I K-AHP), and a slow M-like potassium current (I K-slow). These ionic currents could take part, together with others, also to different aspects of neuronal excitability like responses to depolarizing and hyperpolarizing current injection. However, the ionic mechanisms and their interactions remained largely hypothetical. In this work, we have investigated the mechanisms of Golgi cell excitability by developing a computational model. The model predicts that pacemaking is sustained by subthreshold oscillations tightly coupled to spikes. I Na-p and I K-slow emerged as the critical determinants of oscillations. I h also played a role by setting the oscillatory mechanism into the appropriate membrane potential range. I K-AHP, though taking part to the oscillation, appeared primarily involved in regulating the ISI following spikes. The combination with other currents, in particular a resurgent sodium current (I Na-r) and an A-current (I K-A), allowed a precise regulation of response frequency and delay. These results provide a coherent reconstruction of the ionic mechanisms determining Golgi cell intrinsic electroresponsiveness and suggests important implications for cerebellar signal processing, which will be fully developed in a companion paper (Solinas et al., 2008. Front. Neurosci. 2:4). PMID:18946520

  8. Sustaining cyborgs: sensing and tuning agencies of pacemakers and implantable cardioverter defibrillators.

    PubMed

    Oudshoorn, Nelly

    2015-02-01

    Recently there has been a renewed interest in cyborgs, and particularly in new and emerging fusions of humans and technologies related to the development of human enhancement technologies. These studies reflect a trend to follow new and emerging technologies. In this article, I argue that it is important to study 'older' and more familiar cyborgs as well. Studying 'the old' is important because it enables us to recognize hybrids' embodied experiences. This article addresses two of these older hybrids: pacemakers and implantable cardioverter defibrillators inserted in the bodies of people suffering from heart-rhythm disturbances. My concern with hybrid bodies is that internal devices seem to present a complex and neglected case if we wish to understand human agency. Their 'users' seem to be passive because they cannot exert any direct control over the working of their devices. Technologies inside bodies challenge a longstanding tradition of theorizing human-technology relations only in terms of technologies external to the body. Cyborg theory is problematic as well because most studies tend to conceptualize the cyborg merely as a discursive entity and silence the voices of people living as cyborgs. Inspired by feminist research that foregrounds the materiality of the lived and intimate relations between bodies and technologies, I argue that creating these intimate relations requires patients' active involvement in sustaining their hybrid bodies. Based on observations of these monitoring practices in a Dutch hospital and interviews with patients and technicians, the article shows that heart cyborgs are far from passive. On the contrary, their unique experience in sensing the entangled agencies of technologies and their own heart plays a crucial role in sustaining their hybrid bodies. PMID:25803917

  9. Optimization of Density and Radiated Power Evolution Control using Magnetic ELM Pace-making in NSTX

    SciTech Connect

    Canik, John [ORNL; Maingi, Rajesh [ORNL; Sontag, Aaron C [ORNL; Bell, R. E. [Princeton Plasma Physics Laboratory (PPPL); Gates, D.A. [Princeton Plasma Physics Laboratory (PPPL); Gerhardt, S.P. [Princeton Plasma Physics Laboratory (PPPL); Kugel, H. [Princeton Plasma Physics Laboratory (PPPL); LaBlanc, B. P. [Princeton Plasma Physics Laboratory (PPPL); Menard, J. [Princeton Plasma Physics Laboratory (PPPL); Paul, S.F. [Princeton Plasma Physics Laboratory (PPPL); Sabbagh, S. A. [Columbia University; Soukhanovskii, V. A. [Lawrence Livermore National Laboratory (LLNL)

    2010-01-01

    Recent experiments at the National Spherical Torus Experiment (NSTX) have shown that lithium coating of the plasma facing components leads to improved energy confinement, and also the complete suppression of edge-localized modes (ELMs). Due to the lack of ELMs, however, such plasmas suffer from density and radiated power that increase throughout the discharge, often leading to a radiative collapse. Previous experiments have shown that ELMs can be controllably restored into these lithium-conditioned discharges using 3D magnetic perturbations, which reduces impurity accumulation. The use of magnetic ELM pace-making has been optimized to control the evolution of the density and impurity content. Short duration large amplitude 3D field pulses are used, so that the threshold field for destabilization is reached and ELMs triggered quickly, and the field is then removed. A second improvement was made by adding a negative-going pulse to each of the triggering pulses to counteract the vessel eddy currents and reduce time-averaged rotation braking. With these improvements to the triggering waveform, the frequency of the triggered ELMs was increased to over 60 Hz, reducing the average ELM size. The optimum frequency for attaining impurity control while minimizing energy confinement reduction was determined: fairly low frequency ELMs (20 Hz triggering) are sufficient to keep the total radiation fraction below 25% throughout the discharge and avoid radiative collapse, with little reduction in the plasma stored energy. When combined with improved particle fueling, the ELM-pacing technique has been successful in achieving stationary conditions in the line-averaged electron density and total radiated power.

  10. Minimally Invasive Catheter Procedures to Assist Complicated Pacemaker Lead Extraction and Implantation in the Operating Room

    SciTech Connect

    Kroepil, Patric; Lanzman, Rotem S., E-mail: rotemshlomo@yahoo.de; Miese, Falk R.; Blondin, Dirk [University Hospital Duesseldorf, Department of Radiology (Germany); Winter, Joachim [University Hospital Duesseldorf, Department of Cardiovascular Surgery (Germany); Scherer, Axel; Fuerst, Guenter [University Hospital Duesseldorf, Department of Radiology (Germany)

    2011-04-15

    We report on percutaneous catheter procedures in the operating room (OR) to assist complicated manual extraction or insertion of pacemaker (PM) and implantable cardioverter defibrillator leads. We retrospectively reviewed complicated PM revisions and implantations performed between 2004 and 2009 that required percutaneous catheter procedures performed in the OR. The type of interventional procedure, catheter and retrieval system used, venous access, success rates, and procedural complications were analyzed. In 41 (12 female and 29 male [mean age 62 {+-} 17 years]) of 3021 (1.4%) patients, standard manual retrieval of old leads or insertion of new leads was not achievable and thus required percutaneous catheter intervention for retrieval of misplaced leads and/or recanalisation of occluded central veins. Thirteen of 18 (72.2%) catheter-guided retrieval procedures for misplaced (right atrium [RA] or ventricle [RV; n = 3], superior vena cava [n = 2], brachiocephalic vein [n = 5], and subclavian vein [n = 3]) lead fragments in 16 patients were successful. Percutaneous catheter retrieval failed in five patients because there were extremely fixed or adhered lead fragments. Percutaneous transluminal angiography (PTA) of central veins for occlusion or high-grade stenosis was performed in 25 patients. In 22 of 25 patients (88%), recanalization of central veins was successful, thus enabling subsequent lead replacement. Major periprocedural complications were not observed. In the case of complicated manual PM lead implantation or revision, percutaneous catheter-guided extraction of misplaced lead fragments or recanalisation of central veins can be performed safely in the OR, thus enabling subsequent implantation or revision of PM systems in the majority of patients.

  11. [Return to work of a pacemaker bearing worker: the relationship between health problems and electromagnetic interferences].

    PubMed

    Taino, G; Frigerio, F

    2004-01-01

    The potential effects of electromagnetic fields is a problem that interest the public opinion, as the modern society expose all people to electromagnetic non ionizing radiations. The problem has a particular and important meaning facing the return to normal life and work conditions of a cardiopatic subject bearing a pacemaker (PM) or implantable cardioverter defibrillator (ICD). Electromagnetic interferences can produce temporary or permanent malfunctions in these devices. Checking for the absence of electromagnetic interferences is necessary considering that correct functioning of these medical devices is essential for the life of the bearer. Precautions normally adopted by these subjects are generally adequate to ensure protection from interferences present in life environment; for occupational environment, there is often lack of adequate information, also due to late involving of the doctor specialist in occupational health. This work intends to study in depth a specific job, a carpentry-workshop with welding activities, starting with a case of a PM bearer who asked a doctor specialist in occupational health to evaluate the problems involved in his return to work. Electric and magnetic fields produced by equipments present in the workshop were measured and compared to data supplied by the literature to evaluate the possibility of interactions in the normally functioning of implanted electronic devices. On the basis of our experience, we have found some criterions for specific risk assessement to adopt for the definition of operative protocols for return to work of PM or ICD carriers, also considering the lack of specific procedures and indications for the doctor specialist in occupational health. The collected information and data from the literature suggest that welding can be a risk for a subject with PM; as observed in experimental conditions, electromagnetic radiations can alter particular sensitive devices and those with uncorrected settings. PMID:15270435

  12. [Mechanism of outercellular [K+] in generation of pacemaker action potentials in sinoatrial valve of the rabbit].

    PubMed

    Golovko, V A

    2012-02-01

    In a control solution (solution I; 3 mM K+, 35 degrees C) the amplitude of APs of cells in the valve centre was 81 +/- 6 mV (Mean +/- SEM), the maximal upstroke velocity (dV/dtmax) was 19 +/- 4 V/s, velocity slow diastolic depolarization (DD) - 65 +/- 8 mV/s, the rate of spontaneous AP generation was 135 +/- 14 bpm. Hypo K+ (50 %) solution (solution II) decreased slow DD by - 22 % and dV/dtmax by -58 % and the rate of AP generation by 15 % compared to the control solution. In saline solution, decrease of Emax from -68 to -45 mV and four-fold decrease of slow DD and dV/dtmax were registered at the 8th of exposure. After that the Emax noise and origin of early (EADs) and delay (DADs) afterdepolarizations were observed. Comparative analysis of the main AP parameters of SA valve latent pacemaker cells in solution III (without K+) and solution IV (without KC1 and CaCl2) exposure demonstrated that changes of this parameters in solution IV were less then in solution III. It is interesting that in solution IV exposure the phase of the early repolarization (phase 1) was differentiated, dV/dtmax was increased by 21%. The frequency of AP generation decreased by 18 % as in solution with 50% K+. At the same time, EADs were not registered. It seems that the decreasing of the transsarcolemal gradient of K+ depolarized Emax despite Nernst equation. At the same time permeability was decreased for K+ and Na+ ions. That could involve Ca2+ overload and origin of EADs and DADs. PMID:22650070

  13. Left-sided biventricular pacemaker implantation in the presence of persistent left superior vena cava.

    PubMed

    Sankhla, Vineet; Vajifdar, Bhavesh; Shah, Mandar; Lokhandwala, Yash

    2010-01-01

    Persistent Left Superior Vena Cava (PLSVC) is the most common thoracic venous anomaly encountered during device implantation. The most common problems related to the unusual anatomic access to the heart are reaching a convenient pacing site and ensuring stable lead placement. This report describes left sided implantation of RA, RV and LV leads in a patient with a PLSVC who was referred for cardiac resynchronizaiton therapy. The literature regarding the interventional approach for device implantation in patients with PLSVC is reviewed. PMID:21280477

  14. Shox2 mediates Tbx5 activity by regulating Bmp4 in the pacemaker region of the developing heart.

    PubMed

    Puskaric, Sandra; Schmitteckert, Stefanie; Mori, Alessandro D; Glaser, Anne; Schneider, Katja U; Bruneau, Benoit G; Blaschke, Rüdiger J; Steinbeisser, Herbert; Rappold, Gudrun

    2010-12-01

    Heart formation requires a highly balanced network of transcriptional activation of genes. The homeodomain transcription factor, Shox2, is essential for the formation of the sinoatrial valves and for the development of the pacemaking system. The elucidation of molecular mechanisms underlying the development of pacemaker tissue has gained clinical interest as defects in its patterning can be related to atrial arrhythmias. We have analyzed putative targets of Shox2 and identified the Bmp4 gene as a direct target. Shox2 interacts directly with the Bmp4 promoter in chromatin immunoprecipitation assays and activates transcription in luciferase-reporter assays. In addition, ectopic expression of Shox2 in Xenopus embryos stimulates transcription of the Bmp4 gene, and silencing of Shox2 in cardiomyocytes leads to a reduction in the expression of Bmp4. In Tbx5(del/+) mice, a model for Holt-Oram syndrome, and Shox2(-/-) mice, we show that the T-box transcription factor Tbx5 is a regulator of Shox2 expression in the inflow tract and that Bmp4 is regulated by Shox2 in this compartment of the embryonic heart. In addition, we could show that Tbx5 acts cooperatively with Nkx2.5 to regulate the expression of Shox2 and Bmp4. This work establishes a link between Tbx5, Shox2 and Bmp4 in the pacemaker region of the developing heart and thus contributes to the unraveling of the intricate interplay between the heart-specific transcriptional machinery and developmental signaling pathways. PMID:20858598

  15. Shox2 mediates Tbx5 activity by regulating Bmp4 in the pacemaker region of the developing heart

    PubMed Central

    Puskaric, Sandra; Schmitteckert, Stefanie; Mori, Alessandro D.; Glaser, Anne; Schneider, Katja U.; Bruneau, Benoit G.; Blaschke, Rüdiger J.; Steinbeisser, Herbert; Rappold, Gudrun

    2010-01-01

    Heart formation requires a highly balanced network of transcriptional activation of genes. The homeodomain transcription factor, Shox2, is essential for the formation of the sinoatrial valves and for the development of the pacemaking system. The elucidation of molecular mechanisms underlying the development of pacemaker tissue has gained clinical interest as defects in its patterning can be related to atrial arrhythmias. We have analyzed putative targets of Shox2 and identified the Bmp4 gene as a direct target. Shox2 interacts directly with the Bmp4 promoter in chromatin immunoprecipitation assays and activates transcription in luciferase-reporter assays. In addition, ectopic expression of Shox2 in Xenopus embryos stimulates transcription of the Bmp4 gene, and silencing of Shox2 in cardiomyocytes leads to a reduction in the expression of Bmp4. In Tbx5del/+ mice, a model for Holt-Oram syndrome, and Shox2?/? mice, we show that the T-box transcription factor Tbx5 is a regulator of Shox2 expression in the inflow tract and that Bmp4 is regulated by Shox2 in this compartment of the embryonic heart. In addition, we could show that Tbx5 acts cooperatively with Nkx2.5 to regulate the expression of Shox2 and Bmp4. This work establishes a link between Tbx5, Shox2 and Bmp4 in the pacemaker region of the developing heart and thus contributes to the unraveling of the intricate interplay between the heart-specific transcriptional machinery and developmental signaling pathways. PMID:20858598

  16. Multithreaded cardiac CT

    SciTech Connect

    Kachelriess, Marc; Knaup, Michael; Kalender, Willi A. [Institute of Medical Physics, University of Erlangen, Nuernberg (Germany)

    2006-07-15

    Phase-correlated CT, as it is used for cardiac imaging, is the most popular and the most important but also the most demanding special CT application in the clinical routine, today. Basically, it fulfills the four-dimensional imaging task of depicting a quasiperiodically moving object at any desired motion phase with significantly reduced motion artifacts. Although image quality with phase-correlated reconstruction is far better than with standard reconstruction, there are motion artifacts remaining and improvements of temporal resolution are required. As a well-known alternative to simply decreasing rotation time, we consider a spiral cone-beam CT scanner that has G x-ray guns and detectors mounted. We call this a multisource or a multithreaded CT scanner. Aiming for improved temporal resolution the relative temporal resolution {tau}, which measures the fraction of a motion period that enters the image, is studied as a function of the motion rate (heart rate) and the degree of scan overlap (pitch value) for various configurations. The parameters to optimize are the number of threads G and the interthread parameters {delta}{alpha} and {delta}z, which are the angular and the longitudinal separation between adjacent threads, respectively. To demonstrate the improvements approximate image reconstruction of multithreaded raw data is performed by using a generalization of the extended parallel back projection cone-beam reconstruction algorithm [Med. Phys. 31(6), 1623-1641 (2004)] to the case of multithreaded CT. Reconstructions of a simulated cardiac motion phantom and of simulated semi-antropomorphic phantoms are presented for two and three threads and compared to the single-threaded case to demonstrate the potential of multithreaded cardiac CT. Patient data were acquired using a clinical double-threaded CT scanner to validate the theoretical results. The optimum angle {delta}{alpha} between the tubes is 90 deg.for a double-threaded system, and for triple-threaded scanners it is 60 deg.or 120 deg.. In all cases, {delta}z=0 results as an optimum, which means that the threads should be mounted in the same transversal plane. However, the dependency of the temporal resolution on {delta}z is very weak and a longitudinal separation {delta}z{ne}0 would not deteriorate image quality. The mean temporal resolution achievable with an optimized multithreaded CT scanner is a factor of G better than the mean temporal resolution obtained with a single-threaded scanner. The standard reconstructions showed decreased cone-beam artifacts with multithreaded CT compared to the single-threaded case. Our phase-correlated reconstructions demonstrate that temporal resolution is significantly improved with multithreaded CT. The clinical patient data confirm our results.

  17. Stretch-activated nonselective cation channels in urinary bladder myocytes: importance for pacemaker potentials and myogenic response.

    PubMed

    Wellner, M C; Isenberg, G

    1993-01-01

    Filling of the bladder with urine stretches the myocytes in the wall. Stretch activates nonselective cation channels (SACs) thereby constituting a pacemaking mechanism. Once action potentials are triggered, Ca2+ influx through nifedipine-sensitive Ca2+ channels provides activator Ca2+ for the stretch-induced increase in wall tension (myogenic response). An additional component of myogenic response is independent of nifedipine and membrane potential; Ca2+ influx through SACs is large enough to induce Ca2+ release from intracellular stores. PMID:7505666

  18. The Nonlinear Phase Response Curve of the Human Circadian Pacemaker and How Complex Behaviors Might Arise in Nature

    NASA Astrophysics Data System (ADS)

    Leder, Ron S.

    2002-08-01

    Our example from nature is two groups of about 10,000 cells in the brain called Suprachiasmatic Nuclei (SCN) and how light can entrain free running endogenous periodic behavior via the retina's connection to the SCN. Our major question is how a complex behavior like this can arise in nature. Finally presented is a mathematical model and simulation showing how simple periodic signals can be coupled to produce spatio-temporal chaotic behavior and how two complex signals can combine to produce simple coherent behavior with a hypothetical analogy to phase resetting in biological circadian pacemakers.

  19. Cardiac neurones of autonomic ganglia.

    PubMed

    Wallis, D; Watson, A H; Mo, N

    1996-09-01

    The properties of the postganglionic sympathetic neurones supplying the heart and arising in the stellate and adjacent paravertebral ganglia of various species are discussed with respect to their location, morphology, synaptic input and membrane characteristics. Results from our laboratory on the morphology of rat stellate neurones projecting to the heart were obtained either by intracellular injection of hexammine cobaltic (III) chloride or by retrograde labelling of cells using cobalt-lysine complex. Intracellular recordings were made from cells using electrodes filled either with potassium chloride plus hexammine cobaltic chloride or potassium acetate. Neurones which projected axons into cardiac nerve branches arising from the stellate ganglion were termed putative cardiac neurones, because of the possibility that some supply pulmonary targets. Putative cardiac neurones had unbranched axons and were ovoid or polygonal in shape, but showed considerable variation in soma size and in the complexity of dendritic trees. The mean two-dimensional surface area was 463 microns2 and the mean number of primary dendrites was seven. Other studies have found that the morphology of rat stellate ganglion neurones is similar to that of superior cervical ganglion cells. However, in strains of rat displaying spontaneous hypertension, dendritic length may be increased. Histochemical studies do not, as yet, seem to have demonstrated a distinctive neurochemical profile for stellate cardiac neurones, but various types of peptide-containing intraganglionic nerve fibres have been identified in the guinea pig. In our electrophysiological studies, putative cardiac neurones were found to receive a complex presynaptic input arising from the caudal sympathetic trunk and from T1 and T2 thoracic rami. In addition, 16% of cardiac neurones received a synaptic input from the cardiac nerve. The properties of postganglionic parasympathetic neurones distributed in the cardiac plexus and termed intrinsic cardiac neurones are discussed, including the results of studies on cultures of these neurones. PMID:8873060

  20. Cardiac cone-beam CT

    SciTech Connect

    Manzke, Robert [University of London (King's College) (United Kingdom)]. E-mail: robert.manzke@philips.com

    2005-10-15

    This doctoral thesis addresses imaging of the heart with retrospectively gated helical cone-beam computed tomography (CT). A thorough review of the CT reconstruction literature is presented in combination with a historic overview of cardiac CT imaging and a brief introduction to other cardiac imaging modalities. The thesis includes a comprehensive chapter about the theory of CT reconstruction, familiarizing the reader with the problem of cone-beam reconstruction. The anatomic and dynamic properties of the heart are outlined and techniques to derive the gating information are reviewed. With the extended cardiac reconstruction (ECR) framework, a new approach is presented for the heart-rate-adaptive gated helical cardiac cone-beam CT reconstruction. Reconstruction assessment criteria such as the temporal resolution, the homogeneity in terms of the cardiac phase, and the smoothness at cycle-to-cycle transitions are developed. Several reconstruction optimization approaches are described: An approach for the heart-rate-adaptive optimization of the temporal resolution is presented. Streak artifacts at cycle-to-cycle transitions can be minimized by using an improved cardiac weighting scheme. The optimal quiescent cardiac phase for the reconstruction can be determined automatically with the motion map technique. Results for all optimization procedures applied to ECR are presented and discussed based on patient and phantom data. The ECR algorithm is analyzed for larger detector arrays of future cone-beam systems throughout an extensive simulation study based on a four-dimensional cardiac CT phantom. The results of the scientific work are summarized and an outlook proposing future directions is given. The presented thesis is available for public download at www.cardiac-ct.net.

  1. Videoscope-assisted cardiac surgery

    PubMed Central

    Chen, Robert Jeen-Chen

    2014-01-01

    Videoscope-assisted cardiac surgery (VACS) offers a minimally invasive platform for most cardiac operations such as coronary and valve procedures. It includes robotic and thoracoscopic approaches and each has strengths and weaknesses. The success depends on appropriate hardware setup, staff training, and troubleshooting efficiency. In our institution, we often use VACS for robotic left-internal-mammary-artery takedown, mitral valve repair, and various intra-cardiac operations such as tricuspid valve repair, combined Maze procedure, atrial septal defect repair, ventricular septal defect repair, etc. Hands-on reminders and updated references are provided for reader’s further understanding of the topic. PMID:24455172

  2. Cardiac surgery in a fixed-reimbursement environment.

    PubMed

    Scully, H E

    1996-02-01

    Hospital and physician services in Canada are funded by public (government) sources. This article will describe the practice of cardiac surgery in this setting. Federal legislation has prescribed the principles of accessibility, universality, comprehensiveness, portability, and public administration for essential healthcare services in Canada. Provincial and territorial governments are responsible for the provision of services, receiving federal tax and cash transfers that supplement provincial/territorial funds for hospital, physician, and community health services. Hospitals negotiate annually for global budgets. Physicians work as independent contractors in hospitals (and communities) and are usually paid as specified by fee-for-service contracts negotiated at intervals with governments. Cardiac surgical services have been planned conjointly with government. Forty-two centers in Canada serve a population of 28 million. All but three of these centers are located in tertiary teaching hospitals; all but one do more than 200 pumps annually. The rate of cardiac operations is 80 per 100,000 population. In Ontario, the Provincial Adult Cardiac Care Network makes recommendations to governments about the distribution of the 7,600 pumps annually (population, 11 million), rationalizing waiting lists based on an urgency rating scale. Patients requiring emergent/urgent operations are well served. The average waiting time for an elective cardiac operation is 10.5 weeks. The waiting list mortality is less than 0.5%. The Provincial Adult Cardiac Care Network also determines the placement of new programs and participates in creating hospital funding formulas developed from a combination of resource and acuity intensity weighting. Most surgeons hold full-time academic appointments but are funded largely by practice income. Surgical fees average $2,000 (Canada) per case. Overhead, including malpractice insurance, is approximately 45%. All Canadian patients enjoy reasonably timely access to good cardiac surgical care. Further constraints on physician compensation and (academic) hospital funding will compromise this balance. PMID:8572826

  3. Predicting cardiac complications in patients undergoing non-cardiac surgery

    Microsoft Academic Search

    Allan S. Detsky; Howard B. Abrams; John R. McLaughlin; Daniel J. Drucker; Zion Sasson; Nancy Johnston; J. Gerald Scott; Nicholas Forbath; Joseph R. Hilliard

    1986-01-01

    The authors prospectively studied 455 consecutive patients referred to the general medical consultation service for cardiac\\u000a risk assessment prior to non-cardiac surgery, in order to validate a previously derived multifactorial index in their clinical\\u000a setting. They also tested a version of the index that they had modified to reflect factors they believed to be important.\\u000a For patients undergoing major surgery,

  4. Fetal cardiac hypertrophy and cardiac function in diabetic pregnancies

    Microsoft Academic Search

    Jyotsna A. Gandhi; Xiao Yang Zhang; Jack E. Maidman

    1995-01-01

    OBJECTIVE: Our purpose was to evaluate the relationship between fetal cardiac wall hypertrophy and ventricular function in fetuses of metabolically controlled, insulin-requiring diabetics.STUDY DESIGN: M-mode directed fetal echocardiography included measurements of left and right ventricular free wall and interventricular septal thickness and ventricular diastolic and systolic dimensions. Fetal measurements included biparietal diameter, estimation of fetal weight, and cardiac area\\/thoracic area.

  5. Dosimetric review of cardiac implantable electronic device patients receiving radiotherapy.

    PubMed

    Prisciandaro, Joann I; Makkar, Akash; Fox, Colleen J; Hayman, James A; Horwood, Laura; Pelosi, Frank; Moran, Jean M

    2015-01-01

    A formal communication process was established and evaluated for the management of patients with cardiac implantable electronic devices (CIEDs) receiving radiation therapy (RT). Methods to estimate dose to the CIED were evaluated for their appropriateness in the management of these patients. A retrospective, institutional review board (IRB) approved study of 69 patients with CIEDs treated with RT between 2005 and 2011 was performed. The treatment sites, techniques, and the estimated doses to the CIEDs were analyzed and compared to estimates from published peripheral dose (PD) data and three treatment planning systems(TPSs) - UMPlan, Eclipse's AAA and Acuros algorithms. When measurements were indicated, radiation doses to the CIEDs ranged from 0.01-5.06 Gy. Total peripheral dose estimates based on publications differed from TLD measurements by an average of 0.94 Gy (0.05-4.49 Gy) and 0.51 Gy (0-2.74 Gy) for CIEDs within 2.5 cm and between 2.5 and 10 cm of the treatment field edge, respectively. Total peripheral dose estimates based on three TPSs differed from measurements by an average of 0.69 Gy (0.02-3.72 Gy) for CIEDs within 2.5 cm of the field edge. Of the 69 patients evaluated in this study, only two with defibrillators experienced a partial reset of their device during treatment. Based on this study, few CIED-related events were observed during RT. The only noted correlation with treatment parameters for these two events was beam energy, as both patients were treated with high-energy photon beams (16 MV). Differences in estimated and measured CIED doses were observed when using published PD data and TPS calculations. As such, we continue to follow conservative guidelines and measure CIED doses when the device is within 10 cm of the field or the estimated dose is greater than 2 Gy for pacemakers or 1 Gy for defibrillators. PMID:25679176

  6. Is Cardiac Rehabilitation Exercise Feasible for People with Mild Cognitive Impairment?

    PubMed Central

    Intzandt, Brittany; Black, Sandra E.; Lanctôt, Krista L.; Herrmann, Nathan; Oh, Paul; Middleton, Laura E.

    2015-01-01

    Background Exercise is a promising strategy to prevent dementia, but no clinically supervised exercise program is widely available to people with mild cognitive impairment (MCI). The objective was to survey health professionals to assess the feasibility of using cardiac rehabilitation exercise programs for MCI populations. Methods We distributed surveys to: 1) health professionals working in cardiac rehabilitation exercise programs (36/72 responded); and 2) physicians who treat MCI (22/32 responded). Questions addressed clinician and clinic characteristics and feasibility of referring and accommodating people with MCI. Results Most cardiac rehabilitation exercise programs currently treat people with MCI (61.1%). Nearly all were willing and able to accept people with MCI and comorbid vascular risk (91.7%), though only a minority could accept MCI without vascular risk (16.7%). Although most physicians recommend exercise to people with MCI (63.6%), few referred patients with MCI to programs or people to guide exercise (27.3%). However, all physicians (100%) would refer patients with MCI to a cardiac rehabilitation exercise program. Conclusions Our study supports cardiac rehabilitation exercise programs as a feasible model of exercise for patients with MCI with vascular risk. Patients with and without vascular risk could likely be accommodated if program mandates were expanded. PMID:26180562

  7. BET acetyl-lysine binding proteins control pathological cardiac hypertrophy.

    PubMed

    Spiltoir, Jessica I; Stratton, Matthew S; Cavasin, Maria A; Demos-Davies, Kim; Reid, Brian G; Qi, Jun; Bradner, James E; McKinsey, Timothy A

    2013-10-01

    Cardiac hypertrophy is an independent predictor of adverse outcomes in patients with heart failure, and thus represents an attractive target for novel therapeutic intervention. JQ1, a small molecule inhibitor of bromodomain and extraterminal (BET) acetyl-lysine reader proteins, was identified in a high throughput screen designed to discover novel small molecule regulators of cardiomyocyte hypertrophy. JQ1 dose-dependently blocked agonist-dependent hypertrophy of cultured neonatal rat ventricular myocytes (NRVMs) and reversed the prototypical gene program associated with pathological cardiac hypertrophy. JQ1 also blocked left ventricular hypertrophy (LVH) and improved cardiac function in adult mice subjected to transverse aortic constriction (TAC). The BET family consists of BRD2, BRD3, BRD4 and BRDT. BRD4 protein expression was increased during cardiac hypertrophy, and hypertrophic stimuli promoted recruitment of BRD4 to the transcriptional start site (TSS) of the gene encoding atrial natriuretic factor (ANF). Binding of BRD4 to the ANF TSS was associated with increased phosphorylation of local RNA polymerase II. These findings define a novel function for BET proteins as signal-responsive regulators of cardiac hypertrophy, and suggest that small molecule inhibitors of these epigenetic reader proteins have potential as therapeutics for heart failure. PMID:23939492

  8. Cardiac Rehabilitation: Then and Now.

    ERIC Educational Resources Information Center

    Wilson, Philip K.

    1988-01-01

    As more and more patients survive a coronary event, the need for cardiac rehabilitation will increase. The author reviews the history and current status of this field and predicts what lies ahead. (JD)

  9. Cardiac manifestations in systemic sclerosis

    PubMed Central

    Lambova, Sevdalina

    2014-01-01

    Primary cardiac involvement, which develops as a direct consequence of systemic sclerosis (SSc), may manifest as myocardial damage, fibrosis of the conduction system, pericardial and, less frequently, as valvular disease. In addition, cardiac complications in SSc may develop as a secondary phenomenon due to pulmonary arterial hypertension and kidney pathology. The prevalence of primary cardiac involvement in SSc is variable and difficult to determine because of the diversity of cardiac manifestations, the presence of subclinical periods, the type of diagnostic tools applied, and the diversity of patient populations. When clinically manifested, cardiac involvement is thought to be an important prognostic factor. Profound microvascular disease is a pathognomonic feature of SSc, as both vasospasm and structural alterations are present. Such alterations are thought to predict macrovascular atherosclerosis over time. There are contradictory reports regarding the prevalence of atherosclerosis in SSc. According to some authors, the prevalence of atherosclerosis of the large epicardial coronary arteries is similar to that of the general population, in contrast with other rheumatic diseases such as rheumatoid arthritis and systemic lupus erythematosus. However, the level of inflammation in SSc is inferior. Thus, the atherosclerotic process may not be as aggressive and not easily detectable in smaller studies. Echocardiography (especially tissue Doppler imaging), single-photon emission computed tomography, magnetic resonance imaging and cardiac computed tomography are sensitive techniques for earlier detection of both structural and functional scleroderma-related cardiac pathologies. Screening for subclinical cardiac involvement via modern, sensitive tools provides an opportunity for early diagnosis and treatment, which is of crucial importance for a positive outcome. PMID:25276300

  10. CT-guided cardiac electrophysiology

    Microsoft Academic Search

    Farhood Saremi; Trien Dang

    2009-01-01

    Recent advances in cardiac electrophysiology with revolutionary development of transcutaneous procedures have required electrophysiologists\\u000a to have precise knowledge of the spatial anatomy of the heart, and thus, led to the increasing use of cardiac imaging procedures\\u000a such as multidetector CT (MDCT). The introduction of 64-detector (and higher) scanners has made it possible to visualize the\\u000a anatomic landmarks that are essential

  11. NADPH oxidases and cardiac remodelling

    Microsoft Academic Search

    Adam Nabeebaccus; Min Zhang; Ajay M. Shah

    2011-01-01

    A heart under chronic stress undergoes cardiac remodelling, a process that comprises structural and functional changes including\\u000a cardiomyocyte hypertrophy, interstitial fibrosis, contractile dysfunction, cell death and ventricular dilatation. Reactive\\u000a oxygen species (ROS)-dependent modulation of intracellular signalling is implicated in the development of cardiac remodelling.\\u000a Among the different ROS sources that are present in the heart, NADPH oxidases (NOXs) are particularly

  12. Overview of cardiac computed tomography

    Microsoft Academic Search

    Matthew J. Budoff

    2008-01-01

    Cardiac CT (CCT) has evolved rapidly over the past 20 years. Initially designed as a test for myocardial perfusion, CCT has\\u000a developed into a potent screening test for atherosclerosis and a surrogate for invasive angiography (CT angiography). CT angiography,\\u000a with high correlation to invasive angiography, is now being increasingly used in clinical practice as an alternative to cardiac\\u000a catheterization or

  13. Cardiac assessment of veteran endurance athletes: a 12 year follow up study

    PubMed Central

    Hood, S.; Northcote, R. J.

    1999-01-01

    OBJECTIVES: Sustained aerobic dynamic exercise is beneficial in preventing cardiovascular disease. The effect of lifelong endurance exercise on cardiac structure and function is less well documented, however. A 12 year follow up of 20 veteran athletes was performed, as longitudinal studies in such cohorts are rare. METHODS: Routine echocardiography was repeated as was resting, exercise, and 24 hour electrocardiography. RESULTS: Nineteen returned for screening. Mean (SD) age was 67 (6.2) years (range 56-83). Two individuals had had permanent pacemakers implanted (one for symptomatic atrial fibrillation with complete heart block, the other for asystole lasting up to 15 seconds). Only two athletes had asystolic pauses in excess of two seconds compared with seven athletes in 1985. Of these seven, five had no asystole on follow up. Two of these five had reduced their average running distance by about 15-20 miles a week. One athlete sustained an acute myocardial infarction during a competitive race in 1988. Three athletes had undergone coronary arteriography during the 12 years of follow up but none had obstructive coronary artery disease. Ten of 19 (53%) had echo evidence of left ventricular hypertrophy in 1997 but only two (11%) had left ventricular dilatation. Ten athletes had ventricular couplets on follow up compared with only two in 1985. CONCLUSIONS: Although the benefits of moderate regular exercise are undisputed, high intensity lifelong endurance exercise may be associated with altered cardiac structure and function. These adaptations to more extreme forms of exercise merit caution in the interpretation of standard cardiac investigations in the older athletic population. On rare occasions, these changes may be deleterious. ??? PMID:10450477

  14. Intrinsic near-24-h pacemaker period determines limits of circadian entrainment to a weak synchronizer in humans

    NASA Technical Reports Server (NTRS)

    Wright, K. P. Jr; Hughes, R. J.; Kronauer, R. E.; Dijk, D. J.; Czeisler, C. A.

    2001-01-01

    Endogenous circadian clocks are robust regulators of physiology and behavior. Synchronization or entrainment of biological clocks to environmental time is adaptive and important for physiological homeostasis and for the proper timing of species-specific behaviors. We studied subjects in the laboratory for up to 55 days each to determine the ability to entrain the human clock to a weak circadian synchronizing stimulus [scheduled activity-rest cycle in very dim (approximately 1.5 lux in the angle of gaze) light-dark cycle] at three approximately 24-h periods: 23.5, 24.0, and 24.6 h. These studies allowed us to test two competing hypotheses as to whether the period of the human circadian pacemaker is near to or much longer than 24 h. We report here that imposition of a sleep-wake schedule with exposure to the equivalent of candle light during wakefulness and darkness during sleep is usually sufficient to maintain circadian entrainment to the 24-h day but not to a 23.5- or 24.6-h day. Our results demonstrate functionally that, in normally entrained sighted adults, the average intrinsic circadian period of the human biological clock is very close to 24 h. Either exposure to very dim light and/or the scheduled sleep-wake cycle itself can entrain this near-24-h intrinsic period of the human circadian pacemaker to the 24-h day.

  15. Indeterminacy of spatiotemporal cardiac alternans

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaopeng

    2008-07-01

    Cardiac alternans, a beat-to-beat alternation in action potential duration (at the cellular level) or in electrocardiogram morphology (at the whole heart level), is a marker of ventricular fibrillation, a fatal heart rhythm that kills hundreds of thousands of people in the United States each year. Investigating cardiac alternans may lead to a better understanding of the mechanisms of cardiac arrhythmias and eventually better algorithms for the prediction and prevention of such dreadful diseases. In paced cardiac tissue, alternans develops under increasingly shorter pacing period. Existing experimental and theoretical studies adopt the assumption that alternans in homogeneous cardiac tissue is exclusively determined by the pacing period. In contrast, we find that, when calcium-driven alternans develops in cardiac fibers, it may take different spatiotemporal patterns depending on the pacing history. Because there coexist multiple alternans solutions for a given pacing period, the alternans pattern on a fiber becomes unpredictable. Using numerical simulation and theoretical analysis, we show that the coexistence of multiple alternans patterns is induced by the interaction between electrotonic coupling and an instability in calcium cycling.

  16. Global availability of cardiac rehabilitation

    PubMed Central

    Turk-Adawi, Karam; Sarrafzadegan, Nizal; Grace, Sherry L.

    2015-01-01

    Cardiovascular disease (CVD) is the most-prevalent noncommunicable disease and leading cause of death globally. Over 80% of deaths from CVD occur in low-income and middle-income countries (LMICs). To limit the socioeconomic impact of CVD, a comprehensive approach to health care is needed. Cardiac rehabilitation delivers a cost-effective and structured exercise, education, and risk reduction programme, which can reduce mortality by up to 25% in addition to improving a patient’s functional capacity and lowering rehospitalization rates. Despite these benefits and recommendations in clinical practice guidelines, cardiac rehabilitation programmes are grossly under-used compared with revascularization or medical therapy for patients with CVD. Worldwide, only 38.8% of countries have cardiac rehabilitation programmes. Specifically, 68.0% of high-income and 23% of LMICs (8.3% for low-income and 28.2% for middle-income countries) offer cardiac rehabilitation programmes to patients with CVD. Cardiac rehabilitation density estimates range from one programme per 0.1 to 6.4 million inhabitants. Multilevel strategies to augment cardiac rehabilitation capacity and availability at national and international levels, such as supportive public health policies, systematic referral strategies, and alternative models of delivery are needed. PMID:25027487

  17. Intracellular signaling of cardiac fibroblasts.

    PubMed

    Roche, Patricia L; Filomeno, Krista L; Bagchi, Rushita A; Czubryt, Michael P

    2015-03-01

    Long regarded as a mere accessory cell for the cardiomyocyte, the cardiac fibroblast is now recognized as a critical determinant of cardiac function in health and disease. A recent renaissance in fibroblast-centered research has fostered a better understanding than ever before of the biology of fibroblasts and their contractile counterparts, myofibroblasts. While advanced methodological approaches, including transgenics, lineage fate mapping, and improved cell marker identification have helped to facilitate this new work, the primary driver is arguably the contribution of myofibroblasts to cardiac pathophysiology including fibrosis and arrhythmogenesis. Fibrosis is a natural sequel to numerous common cardiac pathologies including myocardial infarction and hypertension, and typically exacerbates cardiovascular disease and progression to heart failure, yet no therapies currently exist to specifically target fibrosis. The regulatory processes and intracellular signaling pathways governing fibroblast and myofibroblast behavior thus represent important points of inquiry for the development of antifibrotic treatments. While steady progress is being made in uncovering the signaling pathways specific for cardiac fibroblast function (including proliferation, phenotype conversion, and matrix synthesis), much of what is currently known of fibroblast signaling mechanisms is derived from noncardiac fibroblast populations. Given the heterogeneity of fibroblasts across tissues, this dearth of information further underscores the need for progress in cardiac fibroblast biological research. © 2015 American Physiological Society. Compr Physiol 5: 721-760, 2015. PMID:25880511

  18. Drosophila Models of Cardiac Disease

    PubMed Central

    Piazza, Nicole; Wessells, R.J.

    2013-01-01

    The fruit fly Drosophila melanogaster has emerged as a useful model for cardiac diseases, both developmental abnormalities and adult functional impairment. Using the tools of both classical and molecular genetics, the study of the developing fly heart has been instrumental in identifying the major signaling events of cardiac field formation, cardiomyocyte specification, and the formation of the functioning heart tube. The larval stage of fly cardiac development has become an important model system for testing isolated preparations of living hearts for the effects of biological and pharmacological compounds on cardiac activity. Meanwhile, the recent development of effective techniques to study adult cardiac performance in the fly has opened new uses for the Drosophila model system. The fly system is now being used to study long-term alterations in adult performance caused by factors such as diet, exercise, and normal aging. The fly is a unique and valuable system for the study of such complex, long-term interactions, as it is the only invertebrate genetic model system with a working heart developmentally homologous to the vertebrate heart. Thus, the fly model combines the advantages of invertebrate genetics (such as large populations, facile molecular genetic techniques, and short lifespan) with physiological measurement techniques that allow meaningful comparisons with data from vertebrate model systems. As such, the fly model is well situated to make important contributions to the understanding of complicated interactions between environmental factors and genetics in the long-term regulation of cardiac performance. PMID:21377627

  19. Thrombolysis and cardiac arrest.

    PubMed

    Maca, J; Kula, R; Jahoda, J; Chylek, V; Gumulec, J

    2010-01-01

    Cardiac arrest (CA) is a serious clinical condition that might be responsible in many cases for death, in other at least for development of irreversible multiple organ dysfunctions. During and after the CA a significant coagulopathy develops causing a decrease in proper tissue perfusion even if an early return of spontaneous circulation (ROSC) is achieved (no-reflow phenomenon). Administration of thrombolytics can solve the problem by destructing the blood clot in both macrocirculation and microcirculation. Results of some clinical trials proving an effectiveness of thrombolysis were published in the literature. Generally, it was done by describing its positive influence on some important clinical outcome measures (24hour survival, number of hospital admissions, better neurological status etc.) without significant increase in the number of bleeding complications. However, recent pivotal evidence based medicine (EBM) trial represented by TROICA study did not confirm the expected positive results. Because of that and also for other reasons (cost, fear of adverse effects, little practice etc.) thrombolysis, although theoretically promising therapeutical intervention, is not overly recommended and used in routine clinical practice in both out-of-hospital and in-hospital settings (Fig. 2, Tab. 4, Ref. 24). Full Text in free PDF www.bmj.sk. PMID:21384750

  20. Cardiac Imaging System

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Although not available to all patients with narrowed arteries, balloon angioplasty has expanded dramatically since its introduction with an estimated further growth to 562,000 procedures in the U.S. alone by 1992. Growth has fueled demand for higher quality imaging systems that allow the cardiologist to be more accurate and increase the chances of a successful procedure. A major advance is the Digital Cardiac Imaging (DCI) System designed by Philips Medical Systems International, Best, The Netherlands and marketed in the U.S. by Philips Medical Systems North America Company. The key benefit is significantly improved real-time imaging and the ability to employ image enhancement techniques to bring out added details. Using a cordless control unit, the cardiologist can manipulate images to make immediate assessment, compare live x-ray and roadmap images by placing them side-by-side on monitor screens, or compare pre-procedure and post procedure conditions. The Philips DCI improves the cardiologist's precision by expanding the information available to him.

  1. Cardiogenic Genes Expressed in Cardiac Fibroblasts Contribute to Heart Development and Repair

    PubMed Central

    Furtado, Milena B.; Costa, Mauro W.; Pranoto, Edward Adi; Salimova, Ekaterina; Pinto, Alex; Lam, Nicholas T.; Park, Anthony; Snider, Paige; Chandran, Anjana; Harvey, Richard P.; Boyd, Richard; Conway, Simon J.; Pearson, James; Kaye, David M.; Rosenthal, Nadia A.

    2014-01-01

    Rationale Cardiac fibroblasts are critical to proper heart function through multiple interactions with the myocardial compartment but appreciation of their contribution has suffered from incomplete characterization and lack of cell-specific markers. Objective To generate an unbiased comparative gene expression profile of the cardiac fibroblast pool, identify and characterize the role of key genes in cardiac fibroblast function, and determine their contribution to myocardial development and regeneration. Methods and Results High-throughput cell surface and intracellular profiling of cardiac and tail fibroblasts identified canonical MSC and a surprising number of cardiogenic genes, some expressed at higher levels than in whole heart. Whilst genetically marked fibroblasts contributed heterogeneously to interstitial but not cardiomyocyte compartments in infarcted hearts, fibroblast-restricted depletion of one highly expressed cardiogenic marker, Tbx20, caused marked myocardial dysmorphology and perturbations in scar formation upon myocardial infarction. Conclusions The surprising transcriptional identity of cardiac fibroblasts, the adoption of cardiogenic gene programs and direct contribution to cardiac development and repair provokes alternative interpretations for studies on more specialized cardiac progenitors, offering a novel perspective for reinterpreting cardiac regenerative therapies. PMID:24650916

  2. [Cardiac rehabilitation in Austria. A need to treat analysis].

    PubMed

    Benzer, Werner; Mayr, Karl; Abbühl, Brigitt

    2003-11-28

    The aim of this analysis is to survey the general demand and current supply of cardiac rehabilitation in Austria on the basis of best evidence practice and to produce recommendations for a cost-effective structure of the entire cardiac rehabilitation system. Following the standards of indication of the Austrian Society of Cardiology an analysis of demand of cardiac rehabilitation has been carried out and juxtaposed with the current supply of facilities for cardiac rehabilitation. According to hospitalizations in the year 2000, 11,630 patients per annum would require inpatient phase II rehabilitation, 6,270 patients institutional based outpatient phase II rehabilitation and 14,319 patients institutional based phase III rehabilitation. In the year 2000, 14,746 patients received treatment in the 9 Austrian inpatient cardiac rehabilitation centres. This number is compared with an annual demand of 11,630 admissions for phase-II treatment. It follows that an equilibrium can be argued for the supply of and demand for inpatient cardiac rehabilitation in Austria. At present, 10 approved institutions in Austria offer outpatient cardiac rehabilitation services. The maximum number of positions for treatment per institution is currently 200-250. Consequently, maximally 2,000-2,500 patients per annum can be treated. In comparison, there exists a calculated demand for 6,270 patients in institutional based outpatient phase II rehabilitation and 14,319 patients in institutional based phase III rehabilitation. Altogether this amounts to a demand for 20,588 positions for treatment per annum. In Austria, the expenditures for inpatient phase II rehabilitation of a patient given an average duration of stay of 28 days, are [symbol: see text] 4,774.-. Presuming 100% compliance, the institutional based outpatient phase II rehabilitation program costs [symbol: see text] 2,760.- per patient. The costs for institutional based phase III rehabilitation services are [symbol: see text] 2,990.- per patient. This number is accompanied by a potential effective reduction of risks for the patients and a potential effective reduction of costs for the carrier as the number of rehospitalizations and recurrent procedures would decrease significantly. At present, the supply of cardiac rehabilitation in Austria is sufficient for inpatient phase II, but insufficient for the institutional based outpatient phase II and mainly phase III. Thus, a striking asymmetry exists between supply and demand. In view of the enduring effects of institutional based phase III rehabilitation, the individual and social use and finally the expected efficiency in terms of costs, this program should at least be offered without limits to all eligible patients. PMID:14743582

  3. Cardiac Workup of Ischemic Stroke

    PubMed Central

    Ustrell, Xavier; Pellisé, Anna

    2010-01-01

    Stroke is the leading cause of disability in developed countries and the third cause of mortality. Up to 15-30% of ischemic strokes are caused by cardiac sources of emboli being associated with poor prognosis and high index of fatal recurrence. In order to establish an adequate preventive strategy it is crucial to identify the cause of the embolism. After a complete diagnostic workup up to 30% of strokes remain with an undetermined cause, and most of them are attributed to an embolic mechanism suggesting a cardiac origin. There is no consensus in the extent and optimal approach of cardiac workup of ischemic stroke. Clinical features along with brain imaging and the study of the cerebral vessels with ultrasonography or MRI/CT based angiography can identify other causes or lead to think about a possible cardioembolic origin. Atrial fibrillation is the most common cause of cardioembolic stroke. Identification of occult atrial fibrillation is essential. Baseline ECG, serial ECG(’s), cardiac monitoring during the first 48 hours, and Holter monitoring have detection rates varying from 4 to 8% each separately. Extended cardiac monitoring with event loop recorders has shown higher rates of detection of paroxysmal atrial fibrillation. Cardiac imaging with echocardiography is necessary to identify structural sources of emboli. There is insufficient data to determine which is the optimal approach. Transthoracic echocardiography has an acceptable diagnostic yield in patients with heart disease but transesophageal echocardiography has a higher diagnostic yield and is necessary if no cardiac sources have been identified in patients with cryptogenic stroke with embolic mechanism. PMID:21804776

  4. Malfunctions of Implantable Cardiac Devices in Patients Receiving Proton Beam Therapy: Incidence and Predictors

    SciTech Connect

    Gomez, Daniel R., E-mail: dgomez@mdanderson.org [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Poenisch, Falk [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Pinnix, Chelsea C. [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Sheu, Tommy [Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Chang, Joe Y. [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Memon, Nada [Department of Cardiology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Mohan, Radhe [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Rozner, Marc A. [Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Dougherty, Anne H. [Department of Cardiology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)

    2013-11-01

    Purpose: Photon therapy has been reported to induce resets of implanted cardiac devices, but the clinical sequelae of treating patients with such devices with proton beam therapy (PBT) are not well known. We reviewed the incidence of device malfunctions among patients undergoing PBT. Methods and Materials: From March 2009 through July 2012, 42 patients with implanted cardiac implantable electronic devices (CIED; 28 pacemakers and 14 cardioverter-defibrillators) underwent 42 courses of PBT for thoracic (23, 55%), prostate (15, 36%), liver (3, 7%), or base of skull (1, 2%) tumors at a single institution. The median prescribed dose was 74 Gy (relative biological effectiveness; range 46.8-87.5 Gy), and the median distance from the treatment field to the CIED was 10 cm (range 0.8-40 cm). Maximum proton and neutron doses were estimated for each treatment course. All CIEDs were checked before radiation delivery and monitored throughout treatment. Results: Median estimated peak proton and neutron doses to the CIED in all patients were 0.8 Gy (range 0.13-21 Gy) and 346 Sv (range 11-1100 mSv). Six CIED malfunctions occurred in 5 patients (2 pacemakers and 3 defibrillators). Five of these malfunctions were CIED resets, and 1 patient with a defibrillator (in a patient with a liver tumor) had an elective replacement indicator after therapy that was not influenced by radiation. The mean distance from the proton beam to the CIED among devices that reset was 7.0 cm (range 0.9-8 cm), and the mean maximum neutron dose was 655 mSv (range 330-1100 mSv). All resets occurred in patients receiving thoracic PBT and were corrected without clinical incident. The generator for the defibrillator with the elective replacement indicator message was replaced uneventfully after treatment. Conclusions: The incidence of CIED resets was about 20% among patients receiving PBT to the thorax. We recommend that PBT be avoided in pacing-dependent patients and that patients with any type of CIED receiving thoracic PBT be followed closely.

  5. Direct Cardiac Reprogramming: From Developmental Biology to Cardiac Regeneration

    PubMed Central

    Qian, Li; Srivastava, Deepak

    2013-01-01

    Heart disease affects millions worldwide and is a progressive condition involving loss of cardiomyocytes. The human heart has limited endogenous regenerative capacity and is thus an important target for novel regenerative medicine approaches. While cell-based regenerative therapies hold promise, cellular reprogramming of endogenous cardiac fibroblasts, which represent more than half of the cells in the mammalian heart, may be an attractive alternative strategy for regenerating cardiac muscle. Recent advances leveraging years of developmental biology point to the feasibility of generating de novo cardiomyocyte-like cells from terminally differentiated non-myocytes in the heart in situ after ischemic damage. Here, we review the progress in cardiac reprogramming methods and consider the opportunities and challenges that lie ahead in refining this technology for regenerative medicine. PMID:24030021

  6. A randomized control trial of cardiac rehabilitation.

    PubMed

    Burgess, A W; Lerner, D J; D'Agostino, R B; Vokonas, P S; Hartman, C R; Gaccione, P

    1987-01-01

    A randomized trial using controls tested whether psycho-social rehabilitation of acute myocardial infarction (MI) patients would improve significantly their return to work rate and assessed the importance of various psychological, social, occupational, socio-demographic, and medical factors in facilitating or impeding rapid return to work. Eighty-nine patients were assigned randomly to participate in an experimental cardiac rehabilitation program (rehab care), and 91 patients were controls who received conventional hospital rehabilitation (usual care). By the first follow-up interview at three months, patients assigned to experimental treatment were significantly less distressed psychologically and less dependent on family support than controls (P = 0.04 and P = 0.05, respectively). By the final follow-up interview at 13 months, there was a marginally significant difference in favor of the experimental group in the frequency of reported deterrents to work resumption (P = 0.07). However, the intervention did not result in a statistically significant difference in the return to work rate (P greater than 0.10). In each group, 88% were back at work by approximately the first year after infarction. In addition, the two groups were similar in the amount of time patients remained out of the workforce (median days rehab care = 75, usual care = 81; P greater than 0.10). A multi-stage data analysis procedure utilizing the Cox regression technique indicated that while several independent variables had significant univariate associations with the length of time patients convalesced, outcome was most influenced by the patient's initial cardiological status and clinical course, by the patterns of family support, and by the several variables measuring the presence of obstacles to resuming work. Our findings suggest that rehabilitation programs intervening on multiple levels (psychological, social, occupational, and physical) may best meet the needs of chronically ill cardiac patients. Results indicate that implementing measures addressing the patient's general psycho-social adjustment to MI may improve existing programs. PMID:3551088

  7. Cardiac memory in humans: vectocardiographic quantification in cardiac resynchronization therapy

    Microsoft Academic Search

    Luigi PadelettiChiara; Chiara Fantappiè; Laura Perrotta; Giuseppe Ricciardi; Paolo Pieragnoli; Marco Chiostri; Sergio Valsecchi; Maria Cristina Porciani; Antonio Michelucci; Fabio Fantini

    2011-01-01

    Background  “Cardiac memory” (CM) refers to a change in repolarization induced by an altered pathway of activation. The effects of biventricular\\u000a pacing on CM induction have not been investigated.\\u000a \\u000a \\u000a \\u000a \\u000a Objective  To investigate the development of CM during cardiac resynchronization therapy (CRT) through vectorcardiography (VCG).\\u000a \\u000a \\u000a \\u000a Methods  Eleven patients undergoing CRT were enrolled. VCG was acquired during spontaneous ventricular activation at baseline and during\\u000a AAI

  8. Cardiac Complications in Acute Ischemic Stroke

    E-print Network

    2011-01-01

    of cardiac function and complications with AIS. EmergencyAIS patients. 50,51 Regarding structural systolic functionAIS (ie, the ischemic penumbra) intrinsic autoregulation of the vasculature is lost, rendering cerebral blood ?ow directly dependent on cardiac function.

  9. CARDIAC SURGERY MORTALITY RATES UK cardiac surgeons have shown the best way to

    E-print Network

    Aickelin, Uwe

    CARDIAC SURGERY MORTALITY RATES UK cardiac surgeons have shown the best way to ensure good clinical cardiac surgeons through the Society for Cardiothoracic Surgery in Great Britain and Ireland offers, UCL. Publishing cardiac surgery mortality rates: lessons for other specialties. BMJ 2013;346:f1139

  10. Cardiac Metastasis from Invasive Thymoma Via the Superior Vena Cava: Cardiac MRI Findings

    SciTech Connect

    Dursun, Memduh, E-mail: memduhdursun@yahoo.com; Sarvar, Sadik; Cekrezi, Bledi [Istanbul University, Istanbul Faculty of Medicine, Department of Radiology (Turkey); Kaba, Erkan [Istanbul University, Istanbul Faculty of Medicine, Department of Thoracic Surgery (Turkey); Bakir, Baris [Istanbul University, Istanbul Faculty of Medicine, Department of Radiology (Turkey); Toker, Alper [Istanbul University, Istanbul Faculty of Medicine, Department of Thoracic Surgery (Turkey)

    2008-07-15

    Cardiac tumors are rare, and metastatic deposits are more common than primary cardiac tumors. We present cardiac magnetic resonance imaging (MRI) findings of a 50-year-old woman with invasive thymoma. Cardiac MRI revealed a heterogeneous, lobulated anterior mediastinal mass invading the superior vena cava and extending to the right atrium. In cine images there was no invasion to the right atrial wall.

  11. Cardiac manifestations in Behcet's disease

    PubMed Central

    Demirelli, Selami; Degirmenci, Husnu; Inci, Sinan; Arisoy, Arif

    2015-01-01

    Summary Behcet's disease (BD) is a chronic inflammatory disorder, with vasculitis underlying the pathophysiology of its multisystemic effects. Venous pathology and thrombotic complications are hallmarks of BD. However, it has been increasingly recognised that cardiac involvement and arterial complications are also important aspects of the course of the disease. Cardiac lesions include pericarditis, endocarditis, intracardiac thrombosis, myocardial infarction, endomyocardial fibrosis, and myocardial aneurysm. Treatment of cardiovascular involvement in BD is largely empirical, and is aimed towards suppressing the vasculitis. The most challenging aspect seems to be the treatment of arterial aneurysms and thromboses due to the associated risk of bleeding. When the prognosis of cardiac involvement in BD is not good, recovery can be achieved through oral anticoagulation, immunosuppressive therapy, and colchicine use. In this review, we summarise the cardiovascular involvement, different manifestations, and treatment of BD. PMID:25984424

  12. Cardiac manifestations in Behcet's disease.

    PubMed

    Demirelli, Selami; Degirmenci, Husnu; Inci, Sinan; Arisoy, Arif

    2015-05-01

    Behcet's disease (BD) is a chronic inflammatory disorder, with vasculitis underlying the pathophysiology of its multisystemic effects. Venous pathology and thrombotic complications are hallmarks of BD. However, it has been increasingly recognised that cardiac involvement and arterial complications are also important aspects of the course of the disease. Cardiac lesions include pericarditis, endocarditis, intracardiac thrombosis, myocardial infarction, endomyocardial fibrosis, and myocardial aneurysm. Treatment of cardiovascular involvement in BD is largely empirical, and is aimed towards suppressing the vasculitis. The most challenging aspect seems to be the treatment of arterial aneurysms and thromboses due to the associated risk of bleeding. When the prognosis of cardiac involvement in BD is not good, recovery can be achieved through oral anticoagulation, immunosuppressive therapy, and colchicine use. In this review, we summarise the cardiovascular involvement, different manifestations, and treatment of BD. PMID:25984424

  13. Mechanical regulation of cardiac development

    PubMed Central

    Lindsey, Stephanie E.; Butcher, Jonathan T.; Yalcin, Huseyin C.

    2014-01-01

    Mechanical forces are essential contributors to and unavoidable components of cardiac formation, both inducing and orchestrating local and global molecular and cellular changes. Experimental animal studies have contributed substantially to understanding the mechanobiology of heart development. More recent integration of high-resolution imaging modalities with computational modeling has greatly improved our quantitative understanding of hemodynamic flow in heart development. Merging these latest experimental technologies with molecular and genetic signaling analysis will accelerate our understanding of the relationships integrating mechanical and biological signaling for proper cardiac formation. These advances will likely be essential for clinically translatable guidance for targeted interventions to rescue malforming hearts and/or reconfigure malformed circulations for optimal performance. This review summarizes our current understanding on the levels of mechanical signaling in the heart and their roles in orchestrating cardiac development. PMID:25191277

  14. Cardiac myofilaments: mechanics and regulation

    NASA Technical Reports Server (NTRS)

    de Tombe, Pieter P.; Bers, D. M. (Principal Investigator)

    2003-01-01

    The mechanical properties of the cardiac myofilament are an important determinant of pump function of the heart. This report is focused on the regulation of myofilament function in cardiac muscle. Calcium ions form the trigger that induces activation of the thin filament which, in turn, allows for cross-bridge formation, ATP hydrolysis, and force development. The structure and protein-protein interactions of the cardiac sarcomere that are responsible for these processes will be reviewed. The molecular mechanism that underlies myofilament activation is incompletely understood. Recent experimental approaches have been employed to unravel the mechanism and regulation of myofilament mechanics and energetics by activator calcium and sarcomere length, as well as contractile protein phosphorylation mediated by protein kinase A. Central to these studies is the question whether such factors impact on muscle function simply by altering thin filament activation state, or whether modulation of cross-bridge cycling also plays a part in the responses of muscle to these stimuli.

  15. Bifid cardiac apex in a 25-year-old male with sudden cardiac death.

    PubMed

    Wu, Annie; Kay, Deborah; Fishbein, Michael C

    2014-01-01

    Although a bifid cardiac apex is common in certain marine animals, it is an uncommon finding in humans. When present, bifid cardiac apex is usually associated with other congenital heart anomalies. We present a case of bifid cardiac apex that was an incidental finding in a 25-year-old male with sudden cardiac death from combined drug toxicity. On gross examination, there was a bifid cardiac apex with a 2-cm long cleft. There were no other significant gross or microscopic abnormalities. This case represents the very rare occurrence of a bifid cardiac apex as an isolated cardiac anomaly. PMID:23928367

  16. Cardiac Crises and the Family Physician Robert

    PubMed Central

    Galliver, Robert H. L.

    1980-01-01

    Family physicians involved in pre-hospital emergency cardiac care need training in basic cardiac life support (BCLS) and advanced cardiac life support (ACLS). They should also become involved in mobilizing community resources to provide necessary equipment and training for the public in CPR. The article outlines the procedure to be followed in cardiac arrest, the contents of a critical care bag, and the administration of various drugs. PMID:21293702

  17. The Treatment of Obesity in Cardiac Rehabilitation

    PubMed Central

    Ades, Philip A.; Savage, Patrick D.; Harvey-Berino, Jean

    2010-01-01

    Obesity is an independent risk factor for the development of coronary heart disease (CHD). At entry into cardiac rehabilitation (CR) over 80% of patients are overweight and over 50% have the metabolic syndrome. Yet, CR programs do not generally include weight loss programs as a programmatic component and weight loss outcomes in CR have been abysmal. A recently published study outlines a template for weight reduction based upon a combination of behavioral weight loss counseling and an approach to exercise that maximized exercise-related caloric expenditure. This approach to exercise optimally includes walking as the primary exercise modality and eventually requires almost daily longer distance exercise to maximize caloric expenditure. Additionally, lifestyle exercise such as stair climbing and avoidance of energy-saving devices should be incorporated into the daily routine. Risk factor benefits of weight loss and exercise training in overweight patients with coronary heart disease are broad and compelling. Improvements in insulin resistance, lipid profiles, blood pressure, clotting abnormalities, endothelial-dependent vasodilatory capacity, and measures of inflammation such as C-reactive protein have all been demonstrated. CR/secondary prevention programs can no longer ignore the challenge of obesity management in patients with CHD. Individual programs need to develop clinically effective and culturally sensitive approaches to weight control. Finally, multicenter randomized clinical trials of weight loss in CHD patients with assessment of long-term clinical outcomes need to be performed. PMID:20436355

  18. The visual input stage of the mammalian circadian pacemaking system: I. Is there a clock in the mammalian eye?

    PubMed

    Remé, C E; Wirz-Justice, A; Terman, M

    1991-01-01

    Threads of evidence from recent experimentation in retinal morphology, neurochemistry, electrophysiology, and visual perception point toward rhythmic ocular processes that may be integral components of circadian entrainment in mammals. Components of retinal cell biology (rod outer-segment disk shedding, inner-segment degradation, melatonin and dopamine synthesis, electrophysiological responses) show self-sustaining circadian oscillations whose phase can be controlled by light-dark cycles. A complete phase response curve in visual sensitivity can be generated from light-pulse-induced phase shifting. Following lesions of the suprachiasmatic nuclei, circadian rhythms of visual detectability and rod outer-segment disk shedding persist, even though behavioral activity becomes arrhythmic. We discuss the converging evidence for an ocular circadian timing system in terms of interactions between rhythmic retinal processes and the central suprachiasmatic pacemaker, and propose that retinal phase shifts to light provide a critical input signal. PMID:1773080

  19. Neurological complications of cardiac surgery.

    PubMed

    McDonagh, David L; Berger, Miles; Mathew, Joseph P; Graffagnino, Carmelo; Milano, Carmelo A; Newman, Mark F

    2014-05-01

    As increasing numbers of elderly people undergo cardiac surgery, neurologists are frequently called upon to assess patients with neurological complications from the procedure. Some complications mandate acute intervention, whereas others need longer term observation and management. A large amount of published literature exists about these complications and guidance on best practice is constantly changing. Similarly, despite technological advances in surgical intervention and modifications in surgical technique to make cardiac procedures safer, these advances often create new avenues for neurological injury. Accordingly, rapid and precise neurological assessment and therapeutic intervention rests on a solid understanding of the evidence base and procedural variables. PMID:24703207

  20. Cardiac Syndrome X: update 2014.

    PubMed

    Agrawal, Shilpa; Mehta, Puja K; Bairey Merz, C Noel

    2014-08-01

    Cardiac Syndrome X (CSX), characterized by angina-like chest discomfort, ST segment depression during exercise, and normal epicardial coronary arteries at angiography, is highly prevalent in women. CSX is not benign, and linked to adverse cardiovascular outcomes and a poor quality of life. Coronary microvascular and endothelial dysfunction and abnormal cardiac nociception have been implicated in the pathogenesis of CSX. Treatment includes life-style modification, anti-anginal, anti-atherosclerotic, and anti-ischemic medications. Non-pharmacological options include cognitive behavioral therapy, enhanced external counterpulsation, neurostimulation, and stellate ganglionectomy. Studies have shown the efficacy of individual treatments but guidelines outlining the best course of therapy are lacking. PMID:25091971

  1. Evaluation of quasi periodicity in cardiac rhythm

    Microsoft Academic Search

    Ravindra Sheth; Christopher Druzgalski

    2009-01-01

    Summary form only given. Variability of cardiac activity reflected in electrocardiograms has been of considerable interest and the subject of different studies. In particular, the presented project included development of a scheme for presentation of cardiac activity and a comparative evaluation of heart rate variability. The graphical representation of cardiac rhythm variability is demonstrated in a form of circular displays,

  2. Cardiac Anatomy and Physiology: A Review

    Microsoft Academic Search

    Mary Gavaghan

    1998-01-01

    This article reviews the normal anatomy and physiology of the heart. Understanding the normal anatomic and physiologic relationships described in this article will help perioperative nurses care for patients who are undergoing cardiac procedures. Such knowledge also assists nurses in educating patients about cardiac procedures and about activities that can prevent, reverse, or improve cardiac illness. AORN J 67 (April

  3. Segmentation and Visualization for Cardiac Ablation Procedures

    E-print Network

    Golland, Polina

    present novel medical image analysis methods to improve planning and outcome evaluation of cardiacSegmentation and Visualization for Cardiac Ablation Procedures by Michal Depa B.S., Mc and Visualization for Cardiac Ablation Procedures by Michal Depa Submitted to the Department of Electrical

  4. Advanced Imaging Applications to Cardiac Resynchronization Therapy

    E-print Network

    Zanibbi, Richard

    D ultrasound, and electron paramagnetic imaging. His research includes the development of novelAdvanced Imaging Applications to Cardiac Resynchronization Therapy Justin D. Pearlman Professor of the Center for Imaging Science For Cardiac Resynchronization Therapy the goal is to identify where cardiac

  5. Mathematics and the Heart: Understanding Cardiac Output

    ERIC Educational Resources Information Center

    Champanerkar, Jyoti

    2013-01-01

    This paper illustrates a biological application of the concepts of relative change and area under a curve, from mathematics. We study two biological measures "relative change in cardiac output" and "cardiac output", which are predictors of heart blockages and other related ailments. Cardiac output refers to the quantity of…

  6. The cardiac sodium pump: structure and function

    Microsoft Academic Search

    Alicia A. McDonough; Jeffrey B. Velotta; Robert H. G. Schwinger; Kenneth D. Philipson; Robert A. Farley

    2002-01-01

    Cardiac sodium pumps (Na,K-ATPase) influence cell calcium and contractility by generating the Na + gradient driving Ca ++ extrusion via the Na +\\/Ca ++ exchanger (NCX), and are the receptors for cardiac glycosides such as digitalis which increases cardiac contractility by decreasing the Na + gradient driving Ca ++ extrusion. There are multiple isoforms of the sodium pump expressed in

  7. Cardiac rehabilitation and risk reduction: time to "rebrand and reinvigorate".

    PubMed

    Sandesara, Pratik B; Lambert, Cameron T; Gordon, Neil F; Fletcher, Gerald F; Franklin, Barry A; Wenger, Nanette K; Sperling, Laurence

    2015-02-01

    Atherosclerotic cardiovascular disease (ASCVD) continues to increase annually in the United States along with its associated enormous costs. A multidisciplinary cardiac rehabilitation (CR) and risk reduction program is an essential component of ASCVD prevention and management. Despite the strong evidence for CR in the secondary prevention of ASCVD, it remains vastly underutilized due to significant barriers. The current model of CR delivery is unsustainable and needs significant improvement to provide cost-effective, patient-centered, comprehensive secondary ASCVD prevention. PMID:25634839

  8. Particular Utility of Cardiac Rehabilitation in Relation to Age

    Microsoft Academic Search

    Carl J. Lavie; Richard V. Milani; Ross A. Arena

    Considerable evidence indicates that physical activity, exercise training, and cardio-respiratory fitness provide protection\\u000a in primary and secondary coronary heart disease (CHD) prevention, including in the elderly population. However, cardiac rehabilitation\\u000a and exercise training (CRET) programs have been greatly under-utilized in patients with CHD, and this has been especially\\u000a noted in populations of elderly patients, where CRET services have been covered

  9. Cardiac torsion and electromagnetic fields: the cardiac bioinformation hypothesis.

    PubMed

    Burleson, Katharine O; Schwartz, Gary E

    2005-01-01

    Although in physiology the heart is often referred to as a simple piston pump, there are in fact two additional features that are integral to cardiac physiology and function. First, the heart as it contracts in systole, also rotates and produces torsion due to the structure of the myocardium. Second, the heart produces a significant electromagnetic field with each contraction due to the coordinated depolarization of myocytes producing a current flow. Unlike the electrocardiogram, the magnetic field is not limited to volume conduction and extends outside the body. The therapeutic potential for interaction of this cardioelectromagnetic field both within and outside the body is largely unexplored. It is our hypothesis that the heart functions as a generator of bioinformation that is central to normative functioning of body. The source of this bioinformation is based on: (1) vortex blood flow in the left ventricle; (2) a cardiac electromagnetic field and both; (3) heart sounds; and (4) pulse pressure which produce frequency and amplitude information. Thus, there is a multidimensional role for the heart in physiology and biopsychosocial dynamics. Recognition of these cardiac properties may result in significant implications for new therapies for cardiovascular disease based on increasing cardiac energy efficiency (coherence) and bioinformation from the cardioelectromagnetic field. Research studies to test this hypothesis are suggested. PMID:15823696

  10. Cardiac myxoma with oncocytic change--cardiac oncocytoma?

    PubMed

    Puskarz-Thomas, Skye; Dettrick, Andrew; Pohlner, Peter G

    2012-01-01

    We report the case of an incidental cardiac myxoma that was remarkable for the presence of extensive oncocytic change, a feature that has not be reported previously. The oncocytes most likely represent part of a spectrum of degenerative changes present in the tumor, but the possibility that they are neoplastic is also discussed. PMID:22104003

  11. Health Literacy Predicts Cardiac Knowledge Gains in Cardiac Rehabilitation Participants

    ERIC Educational Resources Information Center

    Mattson, Colleen C.; Rawson, Katherine; Hughes, Joel W.; Waechter, Donna; Rosneck, James

    2015-01-01

    Objective: Health literacy is increasingly recognised as a potentially important patient characteristic related to patient education efforts. We evaluated whether health literacy would predict gains in knowledge after completion of patient education in cardiac rehabilitation. Method: This was a re-post observational analysis study design based on…

  12. Cardiac output monitoring by pressure recording analytical method in cardiac surgery

    Microsoft Academic Search

    Pierpaolo Giomarelli; Bonizella Biagioli; Sabino Scolletta

    2004-01-01

    Objective: A less-invasive method has been developed that may provide an alternative to monitor cardiac output from arterial pressure: beat-to-beat values of cardiac output can be obtained by pressure recording analytical method (PRAM). The purpose of this study was to assess the reliability of cardiac output determination by PRAM in cardiac surgery. Methods: Cardiac output was measured in 28 patients

  13. Cardiac output monitoring by pressure recording analytical method in cardiac surgery

    Microsoft Academic Search

    Pierpaolo Giomarelli; Bonizella Biagioli; Sabino Scolletta; Viale Bracci

    2010-01-01

    Objective: A less-invasive method has been developed that may provide an alternative to monitor cardiac output from arterial pressure: beat-to-beat values of cardiac output can be obtained by pressure recording analytical method (PRAM). The purpose of this study was to assess the reliability of cardiac output determination by PRAM in cardiac surgery. Methods: Cardiac output was measured in 28 patients

  14. Cost-benefit analysis of screening for esophageal and gastric cardiac cancer

    PubMed Central

    Wei, Wen-Qiang; Yang, Chun-Xia; Lu, Si-Han; Yang, Juan; Li, Bian-Yun; Lian, Shi-Yong; Qiao, You-Lin

    2011-01-01

    In 2005, a program named “Early Detection and Early Treatment of Esophageal and Cardiac Cancer” (EDETEC) was initiated in China. A total of 8279 residents aged 40–69 years old were recruited into the EDETEC program in Linzhou of Henan Province between 2005 and 2008. Howerer, the cost-benefit of the EDETEC program is not very clear yet. We conducted herein a cost-benefit analysis of screening for esophageal and cardiac cancer. The assessed costs of the EDETEC program included screening costs for each subject, as well as direct and indirect treatment costs for esophageal and cardiac severe dysplasia and cancer detected by screening. The assessed benefits of this program included the saved treatment costs, both direct and indirect, on esophageal and cardiac cancer, as well as the value of prolonged life due to screening, as determined by the human capital approach. The results showed the screening cost of finding esophageal and cardiac severe dysplasia or cancer ranged from ¥2707 to ¥4512, and the total cost on screening and treatment was ¥13 115–¥14 920. The cost benefit was ¥58 944–¥155 110 (the saved treatment cost, ¥17 730, plus the value of prolonged life, ¥41 214–¥137 380). The ratio of benefit-to-cost (BCR) was 3.95–11.83. Our results suggest that EDETEC has a high benefit-to-cost ratio in China and could be instituted into high risk areas of China. PMID:21352699

  15. Payment of hospital cardiac services.

    PubMed

    Unger, W J

    1991-01-01

    This report describes how acute-care community hospitals in the United States get paid for services when their patients either are entitled to Medicare or Medicaid benefits or subscribe to a Blue Cross or Blue Shield plan, a commercial insurance plan, a health maintenance organization, a preferred provider organization, or some other third-party payment mechanism. The focus of this report is on cardiac services, which are the most common type of inpatient services provided by acute-care community hospitals. Over the past three decades, extraordinary advances in medical and surgical technologies as well as healthier life-styles have cut the annual death rate for coronary heart disease in half. Despite this progress, cardiovascular disease remains the number one cause of hospitalization. On average nationwide, diseases and disorders of the circulatory system are the primary reason for 17 percent of all patient admissions, and among the nation's 35 million Medicare beneficiaries they are the primary reason for 25 percent of all admissions. In the United States heart disease is the leading cause of death and a major cause of morbidity. Its diagnosis and treatment are often complex and costly, often requiring multiple hospitalizations and years of medical management. To focus management attention and resources on the immense cardiology marketplace, many hospitals have hired individuals with strong clinical backgrounds to manage their cardiology programs. These "front-line" managers play a key role in coordinating a hospital's services for patients with cardiovascular disease. Increasingly, these managers are being asked to become active participants in the reimbursement process. This report was designed to meet their needs. Because this report describes common reimbursement principles and practices applicable to all areas of hospital management and because it provides a "tool kit" of analytical, planning, and forecasting techniques, it could also be useful to hospital marketing, planning, finance, and accounting personnel. In addition, the rich reservoir of data contained in the appendixes to this report may be of interest to hospital chief executive officers, cardiologists, and cardiovascular surgeons. In addition to the introduction and summary sections, this report contains five main sections. Sequentially, these deal with: the ways hospitals get paid for what they do; ICD-9 coding DRGs, PPS, and Medicare claims administration; ways to analyze how well your hospital is doing; planning and forecasting; the new Resource-Based Relative Value Scale.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:10115896

  16. A portable cadmium telluride multidetector probe for cardiac function monitoring

    NASA Astrophysics Data System (ADS)

    Arntz, Y.; Chambron, J.; Dumitresco, B.; Eclancher, B.; Prat, V.

    1999-06-01

    A new nuclear stethoscope based on a matrix of small CdTe semiconductor detectors has been developed for studying the cardiac performance by gamma ventriculography at the equilibrium, in rest and stress conditions, in the early and recovery phases of the coronary disease and to follow the long-term therapy. The light-weight probe consists of an array of 64 detectors 5×5×2 mm grouped in 16 independent units in a lead shielded aluminum box including 16 preamplifiers. The probe is connected to an electronic box containing DC power supply, 16 channel amplifiers, discriminators and counters, two analog-triggering ECG channels, and interface to a PC. The left ventricle activity is, preferentially, detected by using a low-resolution matching convergent collimator. A physical evaluation of the probe has been performed, both with static tests and dynamically with a hydraulic home-built model of beating heart ventricle paced by a rhythm simulator. The sum of the 16 detectors activity provided a radiocardiogram (RCG) which well depicted the filling and ejection of the cardiac beats, allowing to compare the clinically relevant parameters of the cardiac performance, proportional variables of the stroke volume (SV), ejection fraction (EF) and ventricular flow-rate with the known absolute values programmed on the model. The portable system is now in operation for clinical assessment of cardiac patients.

  17. Noninvasive Cardiac Screening in Young Athletes With Ventricular Arrhythmias

    PubMed Central

    Steriotis, Alexandros Klavdios; Nava, Andrea; Rigato, Ilaria; Mazzotti, Elisa; Daliento, Luciano; Thiene, Gaetano; Basso, Cristina; Corrado, Domenico; Bauce, Barbara

    2013-01-01

    The aim of this study was to analyze using noninvasive cardiac examinations a series of young athletes discovered to have ventricular arrhythmias (VAs) during the preparticipation screening program for competitive sports. One hundred forty-five athletes (mean age 17 ± 5 years) were evaluated. The study protocol included electrocardiography (ECG), exercise testing, 2-dimensional and Doppler echocardiography, 24-hour Holter monitoring, signal-averaged ECG, and in selected cases contrast-enhanced cardiac magnetic resonance imaging. Results of ECG were normal in most athletes (85%). VAs were initially detected prevalently during exercise testing (85%) and in the remaining cases on ECG and Holter monitoring. Premature ventricular complexes disappeared during exercise in 56% of subjects. Premature ventricular complexes during Holter monitoring averaged 4,700 per day, predominantly monomorphic (88%), single, and/or in couplets (79%). The most important echocardiographic findings were mitral valve prolapse in 29 patients (20%), congenital heart disease in 4 (3%), and right ventricular regional kinetic abnormalities in 5 (3.5%). On cardiac magnetic resonance imaging, right ventricular regional kinetic abnormalities were detected in 9 of 30 athletes and were diagnostic of arrhythmogenic right ventricular cardiomyopathy in only 1 athlete. Overall, 30% of athletes were judged to have potentially dangerous VAs. In asymptomatic athletes with prevalently normal ECG, most VAs can be identified by adding an exercise test during preparticipation screening. In conclusion, cardiac screening with noninvasive examinations remains a fundamental tool for the identification of a possible pathologic substrate and for the characterization of electrical instability. PMID:23219000

  18. Fabrication and characterization of bio-engineered cardiac pseudo tissues

    PubMed Central

    Xu, Tao; Baicu, Catalin; Aho, Michael; Zile, Michael; Boland, Thomas

    2014-01-01

    We report to fabricate functional three-dimensional (3D) tissue constructs by using an inkjet based bio-prototyping method. With the use of the modified inkjet printers, contractile cardiac hybrids that exhibit the forms of the 3D rectangular sheet and even the “half heart” (with two connected ventricles) have been fabricated by arranging alternate layers of biocompatible alginate hydrogels and mammalian cardiac cells according to pre-designed 3D patterns. In this study, primary feline adult and H1 cardiomyocytes were used as model cardiac cells. Alginate hydrogels with controlled micro-shell structures were built by spraying cross-linkers in micro drops onto un-gelled alginic acid. The cells remained viable in constructs as thick as 1 cm due to the programmed porosity. Microscopic and macroscopic contractile functions of these cardiomyocytes constructs were observed in vitro. These results suggest that the inkjet bio-prototyping method could be used for hierarchical design of functional cardiac pseudo tissues, balanced with porosity for mass transport and structural support. PMID:20811105

  19. Congenital cardiac disease in dogs.

    PubMed

    Aronson, E; McCaw, D

    1984-09-01

    Aortic stenosis is a heritable cardiac anomaly most common in German Shepherds, Boxers and Newfoundlands, and less common in Pugs, English Bulldogs, Boston Terriers, Fox Terriers, Schnauzers and Bassets. Clinical signs are associated with secondary left-sided heart failure and include coughing, moist rales, exercise intolerance, arrhythmias and a weak femoral pulse. It causes an ejection-type crescendo-decrescendo, systolic murmur best heard on the left side near the elbow. The ECG may be normal or may show signs of left ventricular hypertrophy, including an axis of less than 40 degrees, a QRS complex of greater than 60 seconds in duration, R waves greater than 3 mv in amplitude, ST segment slurring or depression, or T waves of an amplitude greater than 25% of that of R waves. A LAT radiograph usually reveals an enlarged cardiac silhouette, loss of the cranial cardiac waist, and normal pulmonary vasculature, while DV projections show an elongated cardiac silhouette, rounding of the left ventricular border, and a normal descending aorta. Nonselective angiocardiography reveals poststenotic dilatation of the aorta. Treatment of severely affected dogs involves surgical correction. PMID:6482869

  20. Reninoma presenting as cardiac syncope

    PubMed Central

    Tak, Shahid I; Wani, Mohd Lateef; Khan, Khursheed A; Alai, Mohd Sultan; Shera, Altaf Hussain; Ahangar, Abdul G; Khan, Yasir Bashir; Nayeem-ul-Hassan; Irshad, Ifat

    2011-01-01

    Reninoma, a renin-secreting tumor of the juxta-glomerular cells of the kidney, is a rare but surgically treatable cause of secondary hypertension in children. We report a case of reninoma presenting as cardiac syncope with long QTc on electrocardiogram due to hypokalemia. PMID:21677812