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1

Interference with cardiac pacemaker function.  

PubMed

A survey is given of the factors affecting cardiac pacemaker function. Whereas it was earlier considered that external interference was a frequent cause of a pacemaker failure, more recent studies indicate that this is of minor importance. It would appear that failure of pacemaker function due to changes in the QRS-complex, i.e. voltage change, intraventricular conduction defects and frequency changes, intraventricular conduction defects and frequency changes, are more important. A lesser known cause of failure in demand function is the inhibition which arises from skeletal muscle postentials. This appears to be a major problem in some types of pacemaker. Manufacturing defects are unavoidable, and it can still be assumed that electronic component defects may develop in 1 of 1000 pulse generators. Cases with the problem of early run-away pacemaker are still being reported and two such cases are discussed. In one of the patients the run-away phenomenon was intermittent, and was accompanied by a variation in run-away frequency. This possibility should thus always be taken into consideration in a pacemaker patient presenting with snycope. In a patient with a QRS-inhibited pacemaker a double stimulation phenomanen has been observed. PMID:1070234

Ohm, O J

1976-01-01

2

Space Derived Health Aids (Cardiac Pacemaker)  

NASA Technical Reports Server (NTRS)

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.

1981-01-01

3

The influence of elevated 50 Hz electric and magnetic fields on implanted cardiac pacemakers: the role of the lead configuration and programming of the sensitivity.  

PubMed

The influence of the electromagnetic interference (EMI) on performance of 15 implanted cardiac pacemakers (12 generator models) was tested during exposure at a high voltage substation. All patients had an adequate spontaneous heart rate during the study. Tests were performed in the ventricular inhibited mode with unipolar sensing in all pacemakers and repeated with bipolar sensing in four pacemakers. The sensitivity was set to a regular, functionally proper level and then to the highest available level. Exposure was done to moderate (1.2-1.7 kV/m) and strong (7.0-8.0 kV/m) electric fields, which correspond to the immediate vicinity of 110 and 400 kV power lines, respectively. In moderate electric fields the output was inhibited in one pacemaker at regular sensitivity (1.7-3.0 mV) and in five pacemakers at the highest sensitivity (0.5-1.25 mV). In strong electric fields the output was inhibited in five pacemakers at regular sensitivity and several pacemakers converted to noise reversion mode at the highest sensitivity. In bipolar mode only one of four pacemakers at high sensitivity (0.5-1.0 mV) was inhibited in the strongest electric field, whereas all four did so in the unipolar mode. One pacemaker with unipolar sensitivity at 0.5 mV was interfered by 63 microT magnetic field. The results confirm that the programmed sensitivity level and the lead configuration markedly influence pacemakers' vulnerability to EMI. Bipolar sensing mode is rather safe in the presence of EMI, which is encountered in public environments. The programmable features of today's pacemakers permit individualized, less stringent safety measures to avoid electromagnetic hazards. PMID:1723194

Toivonen, L; Valjus, J; Hongisto, M; Metso, R

1991-12-01

4

Mathematical Models of Cardiac Pacemaking Function  

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

5

Epithermal neutron beam interference with cardiac pacemakers.  

PubMed

In this paper, a phantom study was performed to evaluate the effect of an epithermal neutron beam irradiation on the cardiac pacemaker function. Severe malfunction occurred in the pacemakers after substantially lower dose from epithermal neutron irradiation than reported in the fast neutron or photon beams at the same dose rate level. In addition the pacemakers got activated, resulting in nuclides with half-lives from 25 min to 115 d. We suggest that BNCT should be administrated only after removal of the pacemaker from the vicinity of the tumor. PMID:21478029

Koivunoro, H; Serén, T; Hyvönen, H; Kotiluoto, P; Iivonen, P; Auterinen, I; Seppälä, T; Kankaanranta, L; Pakarinen, S; Tenhunen, M; Savolainen, S

2011-12-01

6

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

...FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Therapeutic Devices § 870.5550 External transcutaneous cardiac pacemaker (noninvasive)....

2014-04-01

7

On Quantitative Software Quality Assurance Methodologies for Cardiac Pacemakers  

E-print Network

On Quantitative Software Quality Assurance Methodologies for Cardiac Pacemakers Marta Kwiatkowska an overview of ongoing research aimed at providing software quality as- surance methodologies for pacemakers with a variety of heart and pacemaker models. The framework supports a range of quantitative verification

Oxford, University of

8

Proton Beam Therapy Interference With Implanted Cardiac Pacemakers  

Microsoft Academic Search

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

Yoshiko Oshiro; Shinji Sugahara; Mio Noma; Masato Sato; Yuzuru Sakakibara; Takeji Sakae; Yasutaka Hayashi; Hidetsugu Nakayama; Koji Tsuboi; Nobuyoshi Fukumitsu; Ayae Kanemoto; Takayuki Hashimoto; Koichi Tokuuye

2008-01-01

9

Testing of Common Electromagnetic Environments for Risk of Interference with Cardiac Pacemaker Function  

PubMed Central

Background Cardiac pacemakers are known to be susceptible to strong electromagnetic fields (EMFs). This in vivo study investigated occurrence of electromagnetic interference with pacemakers caused by common environmental sources of EMFs. Methods Eleven volunteers with a pacemaker were exposed to EMFs produced by two mobile phone base stations, an electrically powered commuter train, and an overhead high voltage transmission lines. All the pacemakers were programmed in normal clinically selected settings with bipolar sensing and pacing configurations. Results None of the pacemakers experienced interference in any of these exposure situations. However, often it is not clear whether or not strong EMFs exist in various work environments, and hence an individual risk assessment is needed. Conclusions Modern pacemakers are well shielded against external EMFs, and workers with a pacemaker can most often return to their previous work after having a pacemaker implanted. However, an appropriate risk assessment is still necessary after the implantation of a pacemaker, a change of its generator, or major modification of its programming settings. PMID:24106646

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

2013-01-01

10

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

PubMed Central

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

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

2014-01-01

11

Plethyzmography in assessment of hemodynamic results of pacemaker functions programming  

NASA Astrophysics Data System (ADS)

The paper presents potential role of plethyzmography in optimization of heart hemodynamic function during pacemaker programming. The assessment of optimal stroke volume in patients, with implanted dual chamber pacemaker (DDD), by plethyzmography was a goal of the study. The data were collected during pacing rhythm. 20 patients (8 female and 12 male, average 77.4+/-4.6 years) with dual chamber pacemaker (DDD) and with pacing rhythm during routine pacemaker control and study tests were incorporated in the study group. Hemodynamic parameters were assessed during modification of atrio-ventricular delay (AVD) for pacing rhythm of 70 bpm and 90 bpm. The time of atrioventricular was programmed with 20 ms steps within range 100-200 ms and data were recorded with two minutes delay between two consecutive measurements. Stroke volume (SV) and cardiac output (CO) were calculated from plethyzmographic signal by using Beatscope software (TNO Holand). Highest SV calculated for given pacing rhythm was named optimal stroke volume (OSV) and consequently highest cardiac output was named maximal cardiac output (MCO). The time of atrio-ventricular delay for OSV was named optimal atrioventricular delay (OAVD). The results have showed: mean values of OAVD for 70 bpm - 152+/-33 ms and for 90 bpm -149+/-35 ms, shortening of the mean OAVD time caused by increase of pacing rate from 70 bpm to 90 bpm what resulted in statistically significant decrease of OSV with not statistically significant increase of MCO. The analysis of consecutive patients revealed three types of response to increase of pacing rhythm: 1. typical-shortening of OAVD, 2. neutral-no change of OAVD and 3.atypical-lengthening of OAVD.

Wojciechowski, Dariusz; Sionek, Piotr; Peczalski, Kazimierz; Janusek, Dariusz

2011-01-01

12

Bilateral extracorporeal shock wave lithotripsy in a spinal cord injury patient with a cardiac pacemaker  

Microsoft Academic Search

Objectives: To review the precautions to be observed before and during extracorporeal shock wave lithotripsy (ESWL) in spinal cord injury (SCI) patients with a cardiac pacemaker and the safety of bilateral ESWL performed on the same day.Design: A case report of bilateral ESWL in a SCI patient with a permanent cardiac pacemaker.Setting: The Regional Spinal Injuries Centre, Southport, the Lithotripsy

S Vaidyanathan; R Hirst; KF Parsons; G Singh; BM Soni; T Oo; A Zaidi; JWH Watt; P Sett

2001-01-01

13

The effects of nuclear magnetic resonance on patients with cardiac pacemakers  

SciTech Connect

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

Pavlicek, W. (Cleveland Clinic Foundation, OH); Geisinger, M.; Castle, L.; Borkowski, G.P.; Meaney, T.F.; Bream, B.L.; Gallagher, J.H.

1983-04-01

14

Programmable Pacemaker  

NASA Technical Reports Server (NTRS)

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

1996-01-01

15

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

PubMed

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

Babouri, A; Hedjeidj, A; Guendouz, L

2009-04-01

16

Fatal cardiac thromboembolism in a patient with a pacemaker during ureteroscopic lithotripsy for ureter stone: a case report  

PubMed Central

Intracardiac thrombosis is an infrequent and fatal complication in patients with an inserted pacemaker. A patient with an inserted pacemaker scheduled for ureter stone removal experienced cardiac arrest and cardiopulmonary resuscitation under general anesthesia. Echocardiography showed multiple intracardiac thrombi. Preoperative diagnostic workup including echocardiography for the detection of pacemaker lead thrombus, and the need for anticoagulation should be considered in patients with an inserted pacemaker and high-risk factors for thrombosis.

Chung, Mee Young; Chae, Su Min

2015-01-01

17

QUALITY OF LIFE OF PATIENTS WITH IMPLANTED CARDIAC PACEMAKERS IN NORTH WEST OF IRAN  

Microsoft Academic Search

INTRODUCTION: Introducing a foreign body into the heart, a part of the human anatomy that symbolically represents emotions, is a major life event which may result in a change in the body image, changes in physical and emotional wellbeing and quality of life. METHODS: In a descriptive study in Fall 2006, 78 out of 267 patients with implanted cardiac pacemakers

Fateme Ranjbar Kouchaksaraei; Fariborz Akbarzadeh; Mohammad Hashemi

2007-01-01

18

Capsule endoscopy in patients with cardiac pacemakers, implantable cardioverter defibrillators and left heart assist devices  

PubMed Central

According to the recommendations of the US Food and Drug Administration and manufacturers, capsule endoscopy should not be used in patients carrying implanted cardiac devices. For this review we considered studies indexed (until 30.06.2013) in Medline [keywords: capsule endoscopy, small bowel endoscopy, cardiac pacemaker, implantable cardioverter defibrillator, interference, left heart assist device], technical information from Given Imaging and one own publication (not listed in Medline). Several in vitro and in vivo studies included patients with implanted cardiac devices who underwent capsule endoscopy. No clinically relevant interference was noticed. Initial reports on interference with a simulating device were not reproduced. Furthermore technical data of PillCam (Given Imaging) demonstrate that the maximum transmission power is below the permitted limits for cardiac devices. Hence, impairment of cardiac pacemaker, defibrillator or left ventricular heart assist device function by capsule endoscopy is not expected. However, wireless telemetry can cause dysfunction of capsule endoscopy recording. Application of capsule endoscopy is feasible and safe in patients with implanted cardiac devices such as pacemakers, cardioverter defibrillators, and left heart assist devices. Development of new technologies warrants future re-evaluation. PMID:24714370

Bandorski, Dirk; Höltgen, Reinhard; Stunder, Dominik; Keuchel, Martin

2014-01-01

19

Popeye domain containing proteins are essential for stress-mediated modulation of cardiac pacemaking in mice  

PubMed Central

Cardiac pacemaker cells create rhythmic pulses that control heart rate; pacemaker dysfunction is a prevalent disorder in the elderly, but little is known about the underlying molecular causes. Popeye domain containing (Popdc) genes encode membrane proteins with high expression levels in cardiac myocytes and specifically in the cardiac pacemaking and conduction system. Here, we report the phenotypic analysis of mice deficient in Popdc1 or Popdc2. ECG analysis revealed severe sinus node dysfunction when freely roaming mutant animals were subjected to physical or mental stress. In both mutants, bradyarrhythmia developed in an age-dependent manner. Furthermore, we found that the conserved Popeye domain functioned as a high-affinity cAMP-binding site. Popdc proteins interacted with the potassium channel TREK-1, which led to increased cell surface expression and enhanced current density, both of which were negatively modulated by cAMP. These data indicate that Popdc proteins have an important regulatory function in heart rate dynamics that is mediated, at least in part, through cAMP binding. Mice with mutant Popdc1 and Popdc2 alleles are therefore useful models for the dissection of the mechanisms causing pacemaker dysfunction and could aid in the development of strategies for therapeutic intervention. PMID:22354168

Froese, Alexander; Breher, Stephanie S.; Waldeyer, Christoph; Schindler, Roland F.R.; Nikolaev, Viacheslav O.; Rinné, Susanne; Wischmeyer, Erhard; Schlueter, Jan; Becher, Jan; Simrick, Subreena; Vauti, Franz; Kuhtz, Juliane; Meister, Patrick; Kreissl, Sonja; Torlopp, Angela; Liebig, Sonja K.; Laakmann, Sandra; Müller, Thomas D.; Neumann, Joachim; Stieber, Juliane; Ludwig, Andreas; Maier, Sebastian K.; Decher, Niels; Arnold, Hans-Henning; Kirchhof, Paulus; Fabritz, Larissa; Brand, Thomas

2012-01-01

20

The interference threshold of cardiac pacemakers in electric 50 Hz fields.  

PubMed

The aim of the study was to determine a 'worst-case' and a 'real-case' interference threshold for implanted cardiac pace-makers (CPM) in electric 50 Hz fields as they appear in high-voltage plants, e.g. beneath high voltage overhead lines. For this purpose the resulting electrical potential distribution within the thorax area of volunteers from an external homogeneous electrical 50 Hz field was measured. Different factors such as different body geometries as well as inspiration and expiration of the lung were considered. Measurements showed that 1 per 1 kV m(-1) unimpaired electrical field strength (RMS) an interference voltage of about 180 microVpp as real-case value an 400 microVpp as worst-case value would occur at the input of a unipolar ventricularly controlled, left pectorally implanted cardiac pacemaker. Therefore, it is possible under worst-case conditions but unlikely under practice-relevant conditions that an implanted cardiac pacemaker is disturbed by present electric 50 Hz fields beneath high voltage overhead lines. PMID:11345094

Scholten, A; Silny, J

2001-01-01

21

Functional role of L-type Cav1.3 Ca2+ channels in cardiac pacemaker activity  

PubMed Central

The spontaneous activity of pacemaker cells in the sino-atrial node (SAN) controls the heart rhythm and rate under physiological conditions. Pacemaker activity in SAN cells is due to the presence of the diastolic depolarization, a slow depolarization phase that drives the membrane voltage from the end of an action potential to the threshold of a new action potential. SAN cells express a wide array of ionic channels, but we have limited knowledge about their functional role in pacemaker activity and we still do not know which channels play a prominent role in the generation of the diastolic depolarization. It is thus important to provide genetic evidence linking the activity of genes coding for ionic channels to specific alterations of pacemaker activity of SAN cells. Here, we show that target inactivation of the gene coding for ?1D (Cav1.3) Ca2+ channels in the mouse not only significantly slows pacemaker activity but also promotes spontaneous arrhythmia in SAN pacemaker cells. These alterations of pacemaker activity are linked to abolition of the major component of the L-type current (ICa,L) activating at negative voltages. Pharmacological analysis of ICa,L demonstrates that Cav1.3 gene inactivation specifically abolishes ICa,L in the voltage range corresponding to the diastolic depolarization. Taken together, our data demonstrate that Cav1.3 channels play a major role in the generation of cardiac pacemaker activity by contributing to diastolic depolarization in SAN pacemaker cells. PMID:12700358

Mangoni, Matteo E.; Couette, Brigitte; Bourinet, Emmanuel; Platzer, Josef; Reimer, Daniel; Striessnig, Jörg; Nargeot, Joël

2003-01-01

22

Analysis of complications of permanent transvenous implantable cardiac pacemaker related to operative and postoperative management in 717 consecutive patients.  

PubMed

A retrospective study on complications especially related to operative or postoperative management was carried out in 1000 pacemaker implantations in 717 patients between September, 1972 and December, 1986. In 33 of our series (4.8%), 24 pacing failure occurred within two weeks of implantation. Flange-type leads had the highest incidence of complications. Wedging the electrode close to the longitudinal axis of the heart was found to be the best placing, assuming that the tip of the electrode and the section immediately adjacent were pointing downward. There were 6 cases of diaphragmatic pacing which could not be corrected through programming. No relation with the position of the electrode could be found. We recommend using bipolar pacing to lower the incidence of diaphragmatic pacing. We also had 9 patients with lead fractures (1.3%); these included 3 cases with silicone insulation breaks and 6 cases with wire fractures which occurred closely proximal to the area where the lead was fixed to the vessels. No relationship between the ratio of lead fractures and their brand was found. Five patients developed infections, all of them late postoperatively, over a period of 8 months to 5 years postop. Of these, there were 3 cases with postoperative prolonged hematoma at the pocket site, and 4 cases which had required lead repositioning because of pacing failure. The incidence of infection in our series was low when compared to previous reports, probably due to local use of one gram of Kanamycin during the operation and active chemotherapy performed short term postoperatively. To manage infection of the skin pocket, the pacemaker was removed and a new pacemaker was implanted in the opposite side. There was 7 early postoperative deaths. One of them due to cardiac tamponade caused by perforation of the cardiac wall by temporary electrode lead. The resustation was unsuccessful. PMID:2086564

Matsuura, Y; Yamashina, H; Higo, M; Fujii, T

1990-12-01

23

Prevalence of diabetes in elderly patients requiring permanent cardiac pacemaker insertion.  

PubMed

Diabetes mellitus increases the rate of atrioventricular block after a myocardial infarction; right bundle branch block is more common than expected in the diabetic outpatient population. We decided to assess whether diabetic subjects were more likely to need permanent cardiac pacemaker insertion. Data from patients in Leicestershire who had undergone permanent cardiac pacemaker insertion during a 4-year period were analysed. The capture recapture technique was used: Hospital Activity Analysis data as capture, ward admission book and case note confirmation as recapture. Diabetes coding accuracy was confirmed from the central register and from an analysis of 100 sets of case notes. The number of these patients with diabetes was then recorded. Data for the reference population was obtained using a survey of a market town in Leicestershire. There were 688 patients, most (79%) aged over 65 years. Our analysis was performed on this group. Of this age group undergoing pacemaker insertion. 11.1% was diabetic. In the same age group, 8.3% of the controls were diabetic: a relative risk of 1.34 (P < 0.01, 95% confidence interval 1.25-1.44). This relative risk is likely to be an underestimate. The aetiology of this excess risk is uncertain: it is most likely due to ischaemic heart disease, but microangiopathy or increased cholinergic sensitivity may play a role. PMID:8870822

Lear, J T; Lawrence, I G; Burden, A C

1996-07-01

24

Tricuspid regurgitation in patients with pacemakers and implantable cardiac defibrillators: a comprehensive review.  

PubMed

Implantable cardiac devices, including defibrillators and pacemakers, may be the cause of tricuspid regurgitation (TR) or may worsen existing TR. This review of the literature suggests that TR usually occurs over time after lead implantation. Diagnosis by clinical exam and 2-dimensional echocardiography may be augmented by 3-dimensional echocardiography and/or computed tomography. The mechanism may be mechanical perforation or laceration of leaflets, scarring and restriction of leaflets, or asynchronized activation of the right ventricle. Pacemaker-related TR might cause severe right-sided heart failure, but data regarding associated mortality are lacking. This comprehensive review summarizes the data regarding incidence, mechanism, and treatment of lead-related TR. PMID:23529935

Al-Bawardy, Rasha; Krishnaswamy, Amar; Bhargava, Mandeep; Dunn, Justin; Wazni, Oussama; Tuzcu, E Murat; Stewart, William; Kapadia, Samir R

2013-05-01

25

Prevention of hemodynamic instability in extra-cranial carotid angioplasty and stenting using temporary transvenous cardiac pacemaker.  

PubMed

Hemodynamic instability is a common condition during extra-cranial carotid angioplasty and stenting (CAS). We evaluated the safety and efficacy of prophylactic placement of temporary cardiac pacemaker during extra-cranial CAS for the prevention of hemodynamic instability. For this, forty-seven carotid artery stents were deployed in 41 high-risk patients. Temporary transvenous cardiac pacemakers were inserted before CAS procedure. The pacers were set to capture a heart rate <60 bpm. Clinical symptoms, blood pressure, heart rate, and pacing activation were monitored and data were collected. We found that pacing occurred in 25 carotid lesions during balloon predilatation; pacemakers were activated transiently in 25 patients. The longest pacing continued for 1 day. Among cases with pacemaker activation, 1 patient developed post-procedural symptomatic hypotension that lasted for 4 days. No related complications were observed. It was, therefore, concluded that pacing was technically effective in producing electrical ventricular responses and was hemodynamically effective in 25 carotid lesions which underwent balloon predilatation. The prophylactic use of a temporary transvenous cardiac pacemaker during CAS was rapid and effective in controlling peri-operative hemodynamic instability and preventing stroke and other complications. The prophylactic use of temporary pacemaker is particularly recommended for patients at high risk for developing hemodynamic instability. PMID:23090784

Liu, Juan; Yao, Guo-en; Zhou, Hua-dong; Jiang, Xiao-jiang; Chen, Qiao

2013-03-01

26

A model for predicting electromagnetic interference of implanted cardiac pacemakers by mobile telephones  

Microsoft Academic Search

A prediction of the electromagnetic interference (EMI) of pacemakers due to mobile phones is significant in improving the immunity of pacemakers. The Pacemaker Committee of Japan recently conducted immunity tests of pacemakers for mobile phones, and consequently concluded that the connector between the pacemaker housing and the lead wire of the electrode plays a major role for the EMI due

Jianqing Wang; Osamu Fujiwara; Toshio Nojima

2000-01-01

27

Trends in the incidence and prevalence of cardiac pacemaker insertions in an ageing population  

PubMed Central

Objectives To determine contemporary population estimates of the prevalence of cardiac permanent pacemaker (PPM) insertions. Methods A population-based observational study using linked hospital morbidity and death registry data from Western Australia (WA) to identify all incident cases of PPM insertion for adults aged 18?years or older. Prevalence rates were calculated by age and sex for the years 1995–2009 for the WA population. Results There were 9782 PPMs inserted during 1995–2009. Prevalence rose across the study period, exceeding 1 in 50 among people aged 75 or older from 2005. This was underpinned by incidence rates which rose with age, being highest in those 85?years or older; over 500/100?000 for men throughout, and over 200/100?000 for women. Rates for patients over 75 were more than double the rates for those aged 65–74?years. Women were around 40% of cases overall. The use of dual-chamber and triple-chamber pacing increased across the study period. A cardiac resynchronisation defibrillator was implanted for 58% of patients treated with cardiac resynchronisation therapy. Conclusions Rates of insertion and prevalence of PPM continue to rise with the ageing population in WA. As equilibrium has probably not been reached, the demand for pacing services in similarly well-developed economies is likely to continue to grow. PMID:25512875

Bradshaw, Pamela J; Stobie, Paul; Knuiman, Matthew W; Briffa, Thomas G; Hobbs, Michael S T

2014-01-01

28

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

PubMed

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

Butterfield, Joseph H; Weiler, Catherine R

2014-01-01

29

Pheochromocytoma-Induced Atrial Tachycardia Leading to Cardiogenic Shock and Cardiac Arrest: Resolution with Atrioventricular Node Ablation and Pacemaker Placement  

PubMed Central

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.

Bajaj, Mandeep; Cunningham, Glenn R.

2014-01-01

30

SK4 Ca2+ activated K+ channel is a critical player in cardiac pacemaker derived from human embryonic stem cells  

PubMed Central

Proper expression and function of the cardiac pacemaker is a critical feature of heart physiology. Two main mechanisms have been proposed: (i) the “voltage-clock,” where the hyperpolarization-activated funny current If causes diastolic depolarization that triggers action potential cycling; and (ii) the “Ca2+ clock,” where cyclical release of Ca2+ from Ca2+ stores depolarizes the membrane during diastole via activation of the Na+–Ca2+ exchanger. Nonetheless, these mechanisms remain controversial. Here, we used human embryonic stem cell-derived cardiomyocytes (hESC-CMs) to study their autonomous beating mechanisms. Combined current- and voltage-clamp recordings from the same cell showed the so-called “voltage and Ca2+ clock” pacemaker mechanisms to operate in a mutually exclusive fashion in different cell populations, but also to coexist in other cells. Blocking the “voltage or Ca2+ clock” produced a similar depolarization of the maximal diastolic potential (MDP) that culminated by cessation of action potentials, suggesting that they converge to a common pacemaker component. Using patch-clamp recording, real-time PCR, Western blotting, and immunocytochemistry, we identified a previously unrecognized Ca2+-activated intermediate K+ conductance (IKCa, KCa3.1, or SK4) in young and old stage-derived hESC-CMs. IKCa inhibition produced MDP depolarization and pacemaker suppression. By shaping the MDP driving force and exquisitely balancing inward currents during diastolic depolarization, IKCa appears to play a crucial role in human embryonic cardiac automaticity. PMID:23589888

Weisbrod, David; Peretz, Asher; Ziskind, Anna; Menaker, Nataly; Oz, Shimrit; Barad, Lili; Eliyahu, Sivan; Itskovitz-Eldor, Joseph; Dascal, Nathan; Khananshvili, Daniel; Binah, Ofer; Attali, Bernard

2013-01-01

31

Effects of Epinephrine on the Pacemaker Potassium Current of Cardiac Purkinje Fibers  

PubMed Central

Epinephrine promotes spontaneous activity in cardiac Purkinje fibers through its action on the pacemaker potassium current (iKK2). The mechanism of the acceleratory effect was studied by means of a voltage clamp technique. The results showed that the hormone speeds the deactivation of iKK2 during pacemaker activity by displacing the kinetic parameters of iKK2 toward less negative potentials. This depolarizing voltage shift is the sole explanation of the acceleratory effect since epinephrine did not alter the rectifier properties of iKK2, or the underlying inward leakage current, or the threshold for iNNa. The dose dependence of the voltage shift in the iKK2 activation curve was similar in 1.8 and 5.4 mM [Ca]o. The maximal voltage shift (usually ?20 mV) was produced by epinephrine concentrations of > 10-6 M. The half-maximal effect was evoked by 60 nM epinephrine, nearly an order of magnitude lower than required for half-maximal effect on the secondary inward current (Carmeliet and Vereecke, 1969). The ?-blocker propranolol (10-6 M) prevented the effect of epinephrine (10-7M) but by itself gave no voltage shift. Epinephrine shifted the activation rate coefficient ?8 to a greater extent than the deactivation rate coefficient ?8, and often steepened the voltage dependence of the steady-state activation curve. These deviations from simple voltage shift behavior were discussed in terms of possible mechanisms of epinephrine's action on the iKK2 channel. PMID:4413132

Tsien, Richard W.

1974-01-01

32

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

E-print Network

of safety and reliability. Unfortunately, according to the US Food and Drug Administration (FDA) [1], errors.lastname}@cs.ox.ac.uk Abstract--Implantable medical devices, such as cardiac pace- makers, must be designed and programmed to the highest levels of safety and reliability. Recently, errors in embedded software have led to a substantial

Oxford, University of

33

Analysis of the coupling of electromagnetic interference to unipolar cardiac pacemakers  

Microsoft Academic Search

A theoretical analysis is developed to determine the behaviour of the unipolar pacemaker catheter as a receiving aerial. The\\u000a theory is used to predict the effect of parameters such as the frequency and the length of the catheter on the coupling of\\u000a electromagnetic interference to the pacemaker. The results are presented in terms of an equivalent circuit which is useful

G. S. Smith; J. C. Toler

1981-01-01

34

A Simulink Hybrid Heart Model for Quantitative Verification of Cardiac Pacemakers  

E-print Network

ECG signals. We validate the model by demonstrating that its composition with a pacemaker model can pumps [8] and continuous glucose monitors [16], are stochastic hybrid systems: they involve discrete and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post

Oxford, University of

35

Clinical impact of surface electrocardiography of cardiac arrhythmias in pacemaker-ICD patients  

Microsoft Academic Search

Cardiologists often are called to explain electrocardiograms of pacemaker\\/ implantable cardioverter (PMK\\/ICD) patients during arrhythmic events. The most frequent arrhythmia is atrial fibrillation (AF) whether in PMK or in ICD patients. Generally, it is not difficult to diagnose, it can affect the quality of life of this subgroup because it can generate inappropriate and painful therapies. Arrhythmias as atrioventricular block

Massimo Santini; Stefano Aquilani; Renato Pietro Ricci

36

Clinical Utility and Safety of a Protocol for Noncardiac and Cardiac Magnetic Resonance Imaging of Patients With Permanent Pacemakers and Implantable-Cardioverter Defibrillators at 1.5 Tesla  

PubMed Central

Background Magnetic resonance imaging (MRI) is an important diagnostic modality currently unavailable for millions of patients because of the presence of implantable cardiac devices. We sought to evaluate the diagnostic utility and safety of noncardiac and cardiac MRI at 1.5T using a protocol that incorporates device selection and programming and limits the estimated specific absorption rate of MRI sequences. Methods and Results Patients with no imaging alternative and with devices shown to be MRI safe by in vitro phantom and in vivo animal testing were enrolled. Of 55 patients who underwent 68 MRI studies, 31 had a pacemaker, and 24 had an implantable defibrillator. Pacing mode was changed to “asynchronous” for pacemaker-dependent patients and to “demand” for others. Magnet response and tachyarrhythmia functions were disabled. Blood pressure, ECG, oximetry, and symptoms were monitored. Efforts were made to limit the system-estimated whole-body average specific absorption rate to 2.0 W/kg (successful in >99% of sequences) while maintaining the diagnostic capability of MRI. No episodes of inappropriate inhibition or activation of pacing were observed. There were no significant differences between baseline and immediate or long-term (median 99 days after MRI) sensing amplitudes, lead impedances, or pacing thresholds. Diagnostic questions were answered in 100% of nonthoracic and 93% of thoracic studies. Clinical findings included diagnosis of vascular abnormalities (9 patients), diagnosis or staging of malignancy (9 patients), and assessment of cardiac viability (13 patients). Conclusions Given appropriate precautions, noncardiac and cardiac MRI can potentially be safely performed in patients with selected implantable pacemaker and defibrillator systems. PMID:16966586

Nazarian, Saman; Roguin, Ariel; Zviman, Menekhem M.; Lardo, Albert C.; Dickfeld, Timm L.; Calkins, Hugh; Weiss, Robert G.; Berger, Ronald D.; Bluemke, David A.; Halperin, Henry R.

2011-01-01

37

Small bowel capsule endoscopy in patients with cardiac pacemakers and implantable cardioverter defibrillators: Outcome analysis using telemetry review  

PubMed Central

AIM: To determine if there were any interactions between cardiac devices and small bowel capsules secondary to electromagnetic interference (EMI) in patients who have undergone small bowel capsule endoscopy (SBCE). METHODS: Authors conducted a chart review of 20 patients with a cardiac pacemaker (CP) or implantable cardioverter defibrillator (ICD) who underwent continuous electrocardiographic monitoring during their SBCE from 2003-2008. authors searched for unexplained electrocardiogram (ECG) findings, changes in CP and ICD set parameters, any abnormality in transmitted capsule data, and adverse clinical events. RESULTS: There were no adverse events or hemodynamically significant arrhythmias reported. CP and ICD set parameters were preserved. The majority of ECG abnormalities were also found in pre- or post- SBCE ECG tracings and the CP behavior during arrhythmias appeared appropriate. Two patients seemed to have episodes of undersensing by the CP. However, similar findings were documented in ECGs taken outside the time frame of the SBCE. One patient was observed to have a low signal encountered from the capsule resulting in lack of localization, but no images were lost. CONCLUSION: Capsule-induced EMI remains a possibility but is unlikely to be clinically important. CP-induced interference of SBCE is also possible, but is infrequent and does not result in loss of images transmitted by the capsule. PMID:22442746

Cuschieri, Justin R; Osman, Mohammed N; Wong, Richard CK; Chak, Amitabh; Isenberg, Gerard A

2012-01-01

38

Capsule Endoscopy in Patients with Cardiac Pacemakers and Implantable Cardioverter Defibrillators: (Re)evaluation of the Current State in Germany, Austria, and Switzerland 2010.  

PubMed

Background and Aims. The study was a repeated evaluation of the experience of capsule endoscopy (CE) in patients with cardiac pacemaker or implantable cardioverter defibrillator (ICD). Patients and Methods. A standardized questionnaire was sent by the manufactors Given Imaging and Olympus to all centers in Germany, Austria, and Switzerland providing capsule endoscopy service. The questionnaire covers the number of examined patients, monitoring during CE, check of the electric implants before and after CE, occurrence of arrhythmia, quality of CE video, complications, indication of CE, and type of institution. Results. Overall 580 questionnaires were sent to the users. 26/5% (Germany/Austria + Switzerland) of the questionnaires were sent back anonymously to the authors. 114 centers (82 hospitals, 11 surgeries, 21 without specification) replied. In 58 centers (51%), patients with cardiac pacemaker (n = 300) and ICDs (n = 80) underwent uneventful capsule endoscopy. The predominant indication (patients with CP 97%, patients with ICD 100%) was mid gastrointestinal bleeding. Conclusion. The results of our inquiry show that in spite of formal contraindication CE is increasingly applied in bleeding patients with cardiac pacemakers/ICDs and seems to be safe even in a large cohort. PMID:22253620

Bandorski, Dirk; Jakobs, Ralf; Brück, Martin; Hoeltgen, Reinhard; Wieczorek, Marcus; Keuchel, Martin

2012-01-01

39

AN ULTRA LOW-POWER DYNAMIC TRANSLINEAR CARDIAC SENSE AMPLIFIER FOR PACEMAKERS  

E-print Network

Email:{s.haddad,w.a.serdijn}@its.tudelft.nl 2 Bakken Research Center Medtronic Endepolsdomein 5, 6229 GW Maastricht, The Netherlands Email: richard.houben@medtronic.com ABSTRACT In this paper, a cardiac sense

Serdijn, Wouter A.

40

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

SciTech Connect

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

Sung, Wonmo; Kim, Siyong; Kim, Jung-in; Lee, Jae-gi; Shin, Young-Joo; Jung, Jae-Yong; Ye, Sung-Joon [Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul 110-799, South Korea and Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul 110-744 (Korea, Republic of); Department of Radiation Oncology, Mayo Clinic, Jacksonville, Florida 32224 (United States); Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul 110-799, South Korea and Department of Radiation Oncology, Kangbuk Samsung Medical Center, Seoul 110-746 (Korea, Republic of); Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul 110-744, South Korea and Department of Biomedical Radiation Sciences, Seoul National University, Seoul 151-742 (Korea, Republic of); Department of Radiation Oncology, Sanggye Paik Hospital, Inje University, Seoul 139-707 (Korea, Republic of); Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul 110-799 (Korea, Republic of); Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul 110-744 (Korea, Republic of); Department of Biomedical Radiation Sciences, Seoul National University, Seoul 151-742 (Korea, Republic of); Department of Radiation Oncology, Seoul National University, Seoul 110-799 (Korea, Republic of) and Advanced Institutes of Convergence Technology, Seoul National University, Suwon 443-270 (Korea, Republic of)

2012-10-15

41

Pacemaker current inhibition in experimental human cardiac sympathetic activation: a double-blind, randomized, crossover study.  

PubMed

Hyperpolarization-activated, cyclic nucleotide-gated 4 (HCN4) channels comprise the final pathway for autonomic heart rate (HR) regulation. We hypothesized that HCN4 inhibition could reverse autonomic imbalance in a human model of cardiac sympathetic activation. Nineteen healthy men ingested oral metoprolol+reboxetine, ivabradine+reboxetine, or placebo+reboxetine in a double-blind, randomized, crossover fashion. We assessed HR, blood pressure (BP), stroke volume, and cardiac output during rest and profound orthostatic stress. HR variability, BP variability, and baroreflex sensitivity were analyzed. Metoprolol, but not ivabradine, decreased resting HR and BP. Ivabradine attenuated the HR increase to orthostatic stress, albeit to a lesser extent than metoprolol. Stroke volume and cardiac output at a given HR were significantly lower with metoprolol. Unlike metoprolol, ivabradine did not affect HR variability, BP variability, or baroreflex sensitivity. Ivabradine attenuates sympathetic influences on HR at the sinus node level, leaving myocardial sympathetic activation unopposed. Reversal of parasympathetic dysfunction by ivabradine appears limited. PMID:24509430

Schroeder, C; Heusser, K; Zoerner, A A; Großhennig, A; Wenzel, D; May, M; Sweep, F C G J; Mehling, H; Luft, F C; Tank, J; Jordan, J

2014-06-01

42

[The pacemaker and implantable cardioverter-defibrillator registry of the italian association of arrhythmology and cardiac pacing - annual report 2013].  

PubMed

Background. The pacemaker (PM) and implantable cardioverter-defibrillator (ICD) Registry of the Italian Association of Arrhythmology and Cardiac Pacing (AIAC) monitors the main epidemiological data in real-world practice. The survey for the 2013 activity collects information about demographics, clinical characteristics, main indications for PM/ICD therapy and device types from the Italian collaborating centers. Methods. The Registry collects prospectively national PM and ICD implantation activity on the basis of European cards. Results. PM Registry: data about 25 419 PM implantations were collected (19 134 first implant and 6285 replacements). The number of collaborating centers was 275. Median age of treated patients was 80 years (74 quartile I; 86 quartile III). ECG indications included atrioventricular conduction disorders in 43.6% of first PM implants, sick sinus syndrome in 24.7%, atrial fibrillation plus bradycardia in 12.9%, other in 18.8%. Among atrioventricular conduction defects, third-degree atrioventricular block was the most common type (23.2% of first implants). Use of single-chamber PMs was reported in 27.2% of first implants, of dual-chamber PMs in 62.6%, of PMs with cardiac resynchronization therapy (CRT) in 1.8%, and of single lead atrial-synchronized ventricular stimulation (VDD/R PMs) in 8.4%. ICD Registry: data about 16 519 ICD implantations were collected (11 474 first implants and 5045 replacements). The number of collaborating centers was 430. Median age of treated patients was 71 years (63 quartile I; 77 quartile III). Primary prevention indication was reported in 76% of first implants, secondary prevention in 24.0% (cardiac arrest in 7.8%). A single-chamber ICD was used in 27.2% of first implants, dual-chamber in 35.9% and biventricular in 36.8%. Conclusions. The PM and ICD Registry appears fundamental for monitoring PM and ICD utilization on a large national scale with rigorous examination of demographics and clinical indications. The PM Registry showed stable electrocardiographic and symptom indications, with an important prevalence of dual-chamber pacing. The use of CRT-PM regards a very limited number of patients. The ICD Registry documented a constant increase in prophylactic and biventricular ICD use, reflecting a favorable adherence to trials and guidelines in clinical practice. PMID:25424143

Proclemer, Alessandro; Zecchin, Massimo; D'Onofrio, Antonio; Botto, Giovanni Luca; Rebellato, Luca; Ghidina, Marco; Bianco, Giulia; Bernardelli, Emanuela; Pucher, Elsa; Gregori, Dario

2014-11-01

43

Novel cardiac pacemaker-based human model of periodic breathing to develop real-time, pre-emptive technology for carbon dioxide stabilisation  

PubMed Central

Background Constant flow and concentration CO2 has previously been efficacious in attenuating ventilatory oscillations in periodic breathing (PB) where oscillations in CO2 drive ventilatory oscillations. However, it has the undesirable effect of increasing end-tidal CO2, and ventilation. We tested, in a model of PB, a dynamic CO2 therapy that aims to attenuate pacemaker-induced ventilatory oscillations while minimising CO2 dose. Methods First, pacemakers were manipulated in 12 pacemaker recipients, 6 with heart failure (ejection fraction (EF)=23.7±7.3%) and 6 without heart failure, to experimentally induce PB. Second, we applied a real-time algorithm of pre-emptive dynamic exogenous CO2 administration, and tested different timings. Results We found that cardiac output alternation using pacemakers successfully induced PB. Dynamic CO2 therapy, when delivered coincident with hyperventilation, attenuated 57% of the experimentally induced oscillations in end-tidal CO2: SD/mean 0.06±0.01 untreated versus 0.04±0.01 with treatment (p<0.0001) and 0.02±0.01 in baseline non-modified breathing. This translated to a 56% reduction in induced ventilatory oscillations: SD/mean 0.19±0.09 untreated versus 0.14±0.06 with treatment (p=0.001) and 0.10±0.03 at baseline. Of note, end-tidal CO2 did not significantly rise when dynamic CO2 was applied to the model (4.84±0.47 vs 4.91± 0.45?kPa, p=0.08). Furthermore, mean ventilation was also not significantly increased by dynamic CO2 compared with untreated (7.8±1.2 vs 8.4±1.2?L/min, p=0.17). Conclusions Cardiac pacemaker manipulation can be used to induce PB experimentally. In this induced PB, delivering CO2 coincident with hyperventilation, ventilatory oscillations can be substantially attenuated without a significant increase in end-tidal CO2 or ventilation. Dynamic CO2 administration might be developed into a clinical treatment for PB. Trial Registration number ISRCTN29344450. PMID:25332798

Baruah, Resham; Giannoni, Alberto; Willson, Keith; Manisty, Charlotte H; Mebrate, Yoseph; Kyriacou, Andreas; Yadav, Hemang; Unsworth, Beth; Sutton, Richard; Mayet, Jamil; Hughes, Alun D; Francis, Darrel P

2014-01-01

44

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

PubMed Central

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

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

2014-01-01

45

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

PubMed

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

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

1976-02-01

46

Heart pacemaker  

MedlinePLUS

... ounce. A pacemaker usually has 2 parts: The generator contains the battery and the information to control ... are wires that connect the heart to the generator and carry the electrical messages to the heart. ...

47

[Heart pacemaker with lithium batteries. 2 years' clinical experience].  

PubMed

102 lithium-powered cardiac pacemakers manufactured by Cardiac Pacemakers Inc. (CPI 301 UD, 101 UA and 501 UD) were implanted in 94 patients. During the observation time (25 months) the following complications were registered: 2 pulse generator failures, 4 failures of the demand-function, anodic muscle-twitching in 2 patients, 2 erosions of the pacemaker-pocket and 1 hematoma of the pocket. 5 pulse generators were exchanged without malfunction of the pacemaker. In 4 patients reinterventions on the electrode had, to be performed. 4 deaths occurred, none of them related to malfunction of the pacemaker. 2 lithium-powered pacemakers were explanted in other hospitals, for reasons not known to us and 1 patient left the German Federal Republic. 83 patients are under control with well working lithium-powered pacemakers. PMID:964900

Präuer, H W; Lampadius, M; Wirtzfeld, A; Schmück, L

1976-03-11

48

Cardiac fiber unfolding by semidefinite programming.  

PubMed

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

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

2015-02-01

49

Optogenetic Control of Cardiac Function  

Microsoft Academic Search

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

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

2010-01-01

50

A Programmable Implantable Microstimulator SoC With Wireless Telemetry: Application in Closed-Loop Endocardial Stimulation for Cardiac Pacemaker.  

PubMed

A low-power, wireless, and implantable microstimulator system on chip with smart powering management, immediate neural signal acquisition, and wireless rechargeable system is proposed. A system controller with parity checking handles the adjustable stimulus parameters for the stimulated objective. In the current paper, the rat's intra-cardiac electrogram is employed as the stimulated model in the animal study, and it is sensed by a low-voltage and low-power monitoring analog front end. The power management unit, which includes a rectifier, battery charging and detection, and a regulator, is used for the power control of the internal circuits. The stimulation data and required clock are extracted by a phase-locked-loop-based phase shift keying demodulator from an inductive AC signal. The full chip, which consumes 48 ?W only, is fabricated in a TSMC 0.35 ?m 2P4M standard CMOS process to perform the monitoring and pacing functions with inductively powered communication in the in vivo study. PMID:23852549

Shuenn-Yuh Lee; Su, M Y; Ming-Chun Liang; You-Yin Chen; Cheng-Han Hsieh; Chung-Min Yang; Hsin-Yi Lai; Jou-Wei Lin; Qiang Fang

2011-12-01

51

Effects of Lifestyle Modification Programs on Cardiac Risk Factors  

PubMed Central

Medicare conducted a payment demonstration to evaluate the effectiveness of two intensive lifestyle modification programs in patients with symptomatic coronary artery disease: the Dr. Dean Ornish Program for Reversing Heart Disease (Ornish) and Cardiac Wellness Program of the Benson-Henry Mind Body Institute. This report describes the changes in cardiac risk factors achieved by each program during the active intervention year and subsequent year of follow-up. The demonstration enrolled 580 participants who had had an acute myocardial infarction, had undergone coronary artery bypass graft surgery or percutaneous coronary intervention within 12 months, or had documented stable angina pectoris. Of these, 98% completed the intense 3-month intervention, 71% the 12-month intervention, and 56% an additional follow-up year. Most cardiac risk factors improved significantly during the intense intervention period in both programs. Favorable changes in cardiac risk factors and functional cardiac capacity were maintained or improved further at 12 and 24 months in participants with active follow-up. Multivariable regressions found that risk-factor improvements were positively associated with abnormal baseline values, Ornish program participation for body mass index and systolic blood pressure, and with coronary artery bypass graft surgery. Expressed levels of motivation to lose weight and maintain weight loss were significant independent predictors of sustained weight loss (p?=?0.006). Both lifestyle modification programs achieved well-sustained reductions in cardiac risk factors. PMID:25490202

Razavi, Moaven; Fournier, Stephen; Shepard, Donald S.; Ritter, Grant; Strickler, Gail K.; Stason, William B.

2014-01-01

52

The management of exposed cardiac pacemaker pulse generator and electrode using restricted local surgical interventions; subcapsular relocation and vertical-to-horizontal bow transposition techniques.  

PubMed

This paper describes an approach to the treatment of exposed pacemaker generator and electrode. Local infection is controlled by the administration of systemic antibiotics and topical antibacterial solutions. Because the generator and lead are enveloped by an inert synthetic coating, it is possible to eradicate an infection without their removal if it is due to a weak opportunist pathogen fully sensitive to antibiotics. Thereafter, subcapsular relocation of the exposed generator or vertical-to-horizontal transposition of the exteriorised lead is carried out. These surgical interventions are designed to overcome the vertical force which tends to cause the extrusion of the pacing hardware. PMID:2350636

Har-Shai, Y; Amikam, S; Ramon, Y; Kahir, G; Hirshowitz, B

1990-05-01

53

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

Code of Federal Regulations, 2011 CFR

... (v) Percutaneous transluminal coronary angioplasty (PTCA) or coronary stenting; (vi) A heart or heart-lung transplant. (vii) For cardiac rehabilitation only, other cardiac conditions as specified through a national coverage...

2011-10-01

54

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

... (v) Percutaneous transluminal coronary angioplasty (PTCA) or coronary stenting; (vi) A heart or heart-lung transplant. (vii) For cardiac rehabilitation only, other cardiac conditions as specified through a national coverage...

2014-10-01

55

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

Code of Federal Regulations, 2013 CFR

... (v) Percutaneous transluminal coronary angioplasty (PTCA) or coronary stenting; (vi) A heart or heart-lung transplant. (vii) For cardiac rehabilitation only, other cardiac conditions as specified through a national coverage...

2013-10-01

56

Common pitfalls in interpreting pacemaker electrocardiograms in the emergency department.  

PubMed

The number of patients receiving pacemakers and defibrillators has grown substantially over the last 20 years. In addition, the complexity and sophistication of these devices have increased, making diagnosis of pacemaker problems using the electrocardiogram (ECG) more difficult for clinicians in the emergency department. This article will focus on a few of the pitfalls to be avoided when interpreting paced ECGs. Pacemaker algorithms designed to minimize right ventricular pacing may be confused with pathologic failure to output. Automatic capture threshold detection schemes may be misinterpreted as failure to capture as well as undersensing due to the extra "backup" pacemaker spikes noted on rhythm strips. Device testing done in the emergency department may produce waveforms on monitor resembling ventricular tachycardia if pacemaker-mediated tachycardia is produced accidentally. Ventricular safety pacing algorithms may also be misinterpreted as failure to sense appropriately, triggering questions about pacemaker malfunction. Certain types of true undersensing may resemble morphologies consistent with pacemaker lead dislodgment. In addition, sophisticated programming features designed to mimic normal physiology could be misconstrued as pacemaker malfunction. These include pacemaker hysteresis and sleep mode. The presence of frequent premature ventricular complexes would cause a pacemaker to inhibit ventricular pacing appropriately. However, this could produce a palpated heart rate that is substantially lower than the programmed lower rate of the device due to reduced perfusion by the premature ventricular complexes, again raising questions about the appropriate functioning of the pacemaker. All of these situations will be discussed in detail along with approaches to systematically examining the paced ECGs to minimize the risk of misinterpretation. Pacemaker timing cycles as they relate to troubleshooting of the paced ECG will also be introduced. PMID:21907995

Venkatachalam, K L

2011-01-01

57

Engineered Biological Pacemakers  

Cancer.gov

The National Institute on Aging's Cellular Biophysics Section is seeking statements of capability or interest from parties interested in collaborative research to further develop, evaluate, or commercialize biological pacemakers.

58

Heart pacemaker - discharge  

MedlinePLUS

... pacemaker is placed under your skin. These include: Battery powered cordless tools (such as screwdrivers and drills) Plug-in power tools (such as drills and table saws) Electric lawn mowers and leaf blowers Slot machines Stereo ...

59

A Matlab program to quantify low-SNR pacemaker signals M. Lipphardt, F. Eberhardt*, U.K.H. Wiegand* and U.G. Hofmann  

E-print Network

with a DDDR-type pacemaker (DR 353, Medtronic Inc., Minneapolis) were asked to perform a simple ergometric walking exercise, while the sensing head of the programmer unit (Type 9790, Medtronic Inc., Minneapolis

Lübeck, Universität zu

60

Mastering temporary invasive cardiac pacing.  

PubMed

Competent management of patients with an invasive temporary pacemaker is an important skill for nurses who provide care for critically ill patients with cardiac disease. Such management requires familiarity with normal cardiovascular anatomy and physiology, conduction system defects, and rhythm interpretation. With an understanding of the basic concepts of rate, output, chambers, sensitivity, and capture, pacing can be done with ease. Care of patients with a temporary invasive pacemaker requires monitoring cardiac tissue and hemodynamic status, observing for changes that would indicate the need for modifications in the pacemaker settings. Nursing interventions include physical assessment, care of the insertion site, routine threshold testing, and management of the pulse generator. PMID:15206293

Overbay, Devorah; Criddle, Laura

2004-06-01

61

Effect of cardiac resynchronization therapy with implantable cardioverter defibrillator versus cardiac resynchronization therapy with pacemaker on mortality in heart failure patients: results of a high-volume, single-centre experience  

PubMed Central

Aims There are limited and contradictory data on the effects of CRT with implantable cardioverter defibrillator (CRT-D) on mortality as compared with CRT with pacemaker (CRT-P). Methods and results We evaluated the long-term outcome of patients implanted with a CRT-D or CRT-P device in our high-volume single-centre experience. Data on all-cause mortality were derived from clinic visits and the Hungarian National Healthcare Fund Death Registry. Kaplan–Meier survival analyses and multivariate Cox regression models were used to evaluate all-cause mortality in patients with CRT-D vs. CRT-P, stratified by the aetiology of cardiomyopathy. From 2000 to 2011, 1122 CRT devices, 693 CRT-P (LVEF 28.2?±?7.4%) and 429 CRT-D (LVEF 27.6?±?6.4%), were implanted at our centre. During the median follow-up of 28 months, 379 patients died from any cause, 250 patients (36%) with an implanted CRT-P and 129 patients (30%) with an implanted CRT-D. There was no evidence of mortality benefit in patients implanted with a CRT-D compared with a CRT-P in the total cohort [hazard ratio (HR) 0.98, 95% confidence interval (CI) 0.73–1.32, P?=?0.884]. In patients with ischaemic cardiomyopathy, CRT-D treatment was associated with a significant 30% risk reduction in all-cause mortality compared with an implanted CRT-P (HR 0.70, 95% CI 0.51–0.97, P?=?0.03). In non-ischaemic patients, there was no mortality benefit of CRT-D over CRT-P (HR 0.98, 95% CI 0.73–1.32, P?=?0.894, interaction P-value?=?0.15). Conclusions In heart failure patients with ischaemic cardiomyopathy, CRT-D was associated with a mortality benefit compared with CRT-P, but no benefit of CRT-D over CRT-P in mortality was observed in non-ischaemic cardiomyopathy. PMID:25379962

Kutyifa, Valentina; Geller, Laszlo; Bogyi, Peter; Zima, Endre; Aktas, Mehmet K; Ozcan, Emin Evren; Becker, David; Nagy, Vivien Klaudia; Kosztin, Annamaria; Szilagyi, Szabolcs; Merkely, Bela

2014-01-01

62

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

PubMed

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

Babouri, A; Hedjeidj, A

2007-01-01

63

Pacemaker patients' perception of unsafe activities: a survey  

PubMed Central

Background Cardiac pacing is a recognized and widely used treatment for patients presenting with bradycardia. Physicians expect patients to return to normal activities almost immediately post implantation. However, patients themselves may perceive interference to pacemaker function by various routine activities and devices, and hence continue to lead restricted, disabled lives. The aim of this study is to determine if routine activities are perceived by pacemaker patients to interfere with their device function. Methods A descriptive cross sectional survey was carried out on consecutive patients at the pacemaker clinic at a public hospital in Karachi, Pakistan. A 47-question tool was developed and tested. Patients' perceptions of safety of performing various routine activities, along with socio-demographic data were recorded. Results The final sample included 93 adult patients (45% males). 41% were illiterate. 77.4% recalled receiving counselling at implantation, predominantly from the implanting physician and house staff. A considerable proportion of patients considered many routine activities unsafe including driving automobiles (28%), passing through metal detectors (31%), bending over (37%), and sleeping on the side of the pacemaker (30%). Also considered unsafe were operation of household appliances- TV/VCR (television/video cassette recorders) (53%), irons (55%)) and electrical wall switches (56%). For nearly all variables neither literacy nor history of counselling improved incorrect perceptions. Conclusion This study shows that our pacemaker patients perceive many routine activities as unsafe, potentially leading to disabling life style modifications. The tremendous investment in pacemaker technology to improve patient performance is not going to pay dividends if patients continue to remain disabled due to incorrect perceptions. Further studies are required to determine the reasons for these misperceptions, and to determine if these problems also exist in, and hinder, other patient populations. PMID:19014563

Aqeel, Masooma; Shafquat, Azam; Salahuddin, Nawal

2008-01-01

64

[Anesthetic management of a patient with Fontan circulation with pacemaker failure].  

PubMed

We describe the anesthetic management of a 23-year-old female patient with severe bradycardia due to pacemaker lead disconnection. The pacemaker had been placed due to complete AV block following an extracardiac Fontan operation. She was scheduled for lead repair under general anesthesia. The preoperative HR was only 37 beats x min(-1) of idioventricular rhythm. As further bradycardia was a major concern, we prepared a percutaneous cardiac pacemaker and the catheterization laboratory for transatrial cardiac pacing. After placement of transcutaneous cardiac pacing pads on the chest, we administered isoproterenol at 0.01 microg x kg(-1) x min(-1). We confirmed an increase in HR to 50 beats x min(-1) and induced anesthesia, after which isoproterenol was administered at 0.015 microg x kg(-1) x min(-1). No bradycardia was observed perioperatively. Transvenous cardiac pacing, part of the last step in the ACLS bradycardia algorithm, is inappropriate except in patients with anatomic Fontan circulation. Furthermore, in the case of bradycardia, percutaneous or transesophageal cardiac pacing can be used; however, these are not always effective. Transatrial cardiac pacemakers are probably most effective for bradycardia with Fontan circulation but they should be placed by a catheter specialist, and emergency placement can be difficult. As described here, a special management protocol is necessary to control bradycardia in the face of Fontan circulation. PMID:24364280

Kamata, Mineto; Horimoto, Yoh

2013-11-01

65

How Does a Pacemaker Work?  

MedlinePLUS

... A pacemaker consists of a battery, a computerized generator, and wires with sensors at their tips. (The sensors are called electrodes.) The battery powers the generator, and both are surrounded by a thin metal ...

66

VideoLab: Optogenetic Pacemaker  

NSDL National Science Digital Library

In mammals, the heart's primary pacemaker lies in a specialized group of cells -- but do non-mammalian vertebrates have a similar control system? To find out, Arrenberg et al. genetically engineered zebrafish to express light-sensitive proteins, and then used light beams generated with a digital micromirror device to locate and manipulate the function of the pacemaker cells in the hearts of zebrafish embryos -- capturing the action on high-speed video.

Aristides B. Arrenberg (University of California; University of Freiburg;Department of Physiology; Institute of Biology); Didier Y. R. Stainier (University of California;Department of Biochemistry and Biophysics and Cardiovascular Research Institute); Herwig Baier (University of California;Department of Physiology); Jan Huisken (University of California; Max Planck Institute of Molecular Cell Biology and Genetics;Department of Biochemistry and Biophysics and Cardiovascular Research Institute)

2010-11-12

67

Sinus venosus atrial septal defect: a rare cause of misplacement of pacemaker leads  

PubMed Central

Routine implantation of pacemakers and implantable cardioverter defibrillators is not commonly associated with complications. However, in some cases we see misplacement of pacemaker leads which is most often related to the presence of underlying cardiac anomalies. We report the case of misplacement of a pacemaker lead into the left ventricle of a 56-year-old patient paced in VVI/R mode and with a tined type pacemaker lead because of a symptomatic complete atrioventricular block. Electrocardiogram showed a pacemaker-generated rhythm with a right bundle branch block pattern. Chest X-ray showed the pacemaker lead located relatively high in relation to the diaphragm. Echocardiography visualized the pacemaker lead in the left heart chambers (atrium and ventricle), hence confirming its aberrant course. Further, the defect causing its passage to the left heart chambers was a sinus venosus atrial septal defect. The patient reported no complication related to the misplacement of the lead. After a brief period of oral anticoagulation, the lead was inserted into the right ventricle by percutaneous technique. PMID:23847433

Bodian, Malick; Aw, Fatou; Bamba, Mouhamadou Ndiaye; Kane, Adama; Jobe, Modou; Tabane, Alioune; Mbaye, Alassane; Sarr, Simon Antoine; Diao, Maboury; Sarr, Moustapha; Bâ, Serigne Abdou

2013-01-01

68

Hydrogen-induced microelectronic capacitor failure in pacemakers.  

PubMed

Ceramic chip capacitors used in hybrid microelectronics for cardiac pacemakers are usually highly reliable. However, under certain conditions of capacitor construction, capacitor materials, mounting techniques, and environmental conditions, high failure rates may occur. A specific example is presented in which a ceramic capacitor used in an implanted pacemaker delaminated and failed approximately 30 days after being implanted. The failed capacitor caused a pulse rate rise, but due to circuit design techniques, the rate increase was limited to an acceptable value. The capacitor that failed was from an isolated lot of capacitors that was manufactured using pure palladium plates. The circuit containing this capacitor was hermetically sealed within a titanium case by welding. During the welding, a small amount of hydrogen was released from the titanium which, over a period of 2 to 4 weeks, was absorbed by the palladium plates in the capacitor. By absorbing the hydrogen, the palladium plates exhibit a volumetric expansion of sufficient magnitude to crack and delaminate the capacitor to the point of failure. Subsequently, the recurrence of this failure mode has been avoided by using capacitors containing special palladium alloys that cannot absorb hydrogen. This phenomenon is of interest to pacemaker designers since mercury batteries used in conventional pacemakers generate large amounts of hydrogen and potentially may be responsible for complications when used in conjunction with capacitors containing palladium. PMID:958043

Rainer, W G; Kolenik, S A; Whittaker, R E; Sadler, T R; Lapin, E S

1976-01-01

69

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

PubMed Central

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.

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

2015-01-01

70

How Will a Pacemaker Affect My Lifestyle?  

MedlinePLUS

... this page from the NHLBI on Twitter. How Will a Pacemaker Affect My Lifestyle? Once you have ... are safe for you. Ongoing Care Your doctor will want to check your pacemaker regularly (about every ...

71

Design and Testing of a Percutaneously Implantable Fetal Pacemaker  

PubMed Central

We are developing a cardiac pacemaker with a small, cylindrical shape that permits percutaneous implantation into a fetus to treat complete heart block and consequent hydrops fetalis, which can otherwise be fatal. The device uses off-the-shelf components including a rechargeable lithium cell and a highly efficient relaxation oscillator encapsulated in epoxy and glass. A corkscrew electrode made from activated iridium can be screwed into the myocardium, followed by release of the pacemaker and a short, flexible lead entirely within the chest of the fetus to avoid dislodgement from fetal movement. Acute tests in adult rabbits demonstrated the range of electrical parameters required for successful pacing and the feasibility of successfully implanting the device percutaneously under ultrasonic imaging guidance. The lithium cell can be recharged inductively as needed, as indicated by a small decline in the pulsing rate. PMID:22855119

Loeb, Gerald E.; Zhou, Li; Zheng, Kaihui; Nicholson, Adriana; Peck, Raymond A.; Krishnan, Anjana; Silka, Michael; Pruetz, Jay; Chmait, Ramen; Bar-Cohen, Yaniv

2012-01-01

72

Ventricular perforation by pacemaker lead repaired with two hemostatic devices  

PubMed Central

INTRODUCTION Cardiac perforation is a rare, but potentially serious, complication of pacemaker implantation that may develop days or weeks after implantation. PRESENTATION OF CASE In the current case, 92-year-old man underwent permanent pacemaker implantation, but he presented 3 weeks later with severe symptoms. Computed tomography showed protrusion of the tip of the ventricular electrode through the right ventricle and into the chest wall. During an urgent surgical intervention, the lead was disconnected and extracted. A sealing hemostatic device and an hemostatic patch were applied to repair the ventricle; the procedure was uneventfull. DISCUSSION This case demonstrates how the correct diagnosis of ventricular perforation is crucial, and should be followed immediately by surgical planning. CONCLUSION The hemostatic patch is a valuable alternative to sutures in patients with thin and fragile ventricular wall, unable to undergo stitching. PMID:25460433

Prestipino, Filippo; Nenna, Antonio; Casacalenda, Adele; Chello, Massimo

2014-01-01

73

Comparison of the normal sinus node with seven types of rate responsive pacemaker during everyday activity.  

PubMed Central

The heart rate response of 59 patients aged 17-79 years implanted with seven different types of rate responsive pacemakers was evaluated during graded exercise treadmill testing and during standardised daily activities. The heart rate response in patients with pacemakers was compared with the chronotropic response in 20 healthy controls of similar age and sex distribution who performed identical protocols. All pacemaker types adequately simulated the control heart rate response during the graded exercise treadmill test except during the early stages of exercise. However, during everyday activities, the response of ventricular rate responsive (VVIR) pacemakers was varied. Activity sensing systems rapidly overresponded to staircase descent, to changes in walking speed, and to suitcase lifting with the pacemaker arm, and these systems did not respond to mental stress. "Physiological" sensors (QT and minute ventilation units) responded slowly to rapid changes in physiological demand. The QT pacemaker patients did respond to mental stress but showed a paradoxical increase in rate during the recovery phases of burst exercise protocols such as staircase ascent/descent and walking deceleration. Dual chamber pacemakers in VDD, DDD, and DDDR modes most closely simulated the normal chronotropic response during everyday activities. Graded exercise treadmill testing, in isolation, may not be the best way to asses or program the heart rate response in patients with the heart rate adaptive pacemakers because changes in heart rate during everyday activities may deviate considerably from the normal sinus response despite satisfactory simulation of the normal chronotropic response during treadmill testing. PMID:2390399

Sulke, A N; Pipilis, A; Henderson, R A; Bucknall, C A; Sowton, E

1990-01-01

74

Clinical experience with a new multiprogrammable dual chamber pacemaker.  

PubMed

We evaluated the clinical performance of a new dual chamber pacemaker, ELA Chorus, in 35 patients. This device incorporates linear rate adaptive AV delay (AVDR), rate smoothing, fallback, impedance telemetry, pacemaker mediated tachycardia (PMT) recognition and reprogramming software, intracardiac electrogram displays, autothreshold testing, diagnostic data, battery depletion curves, and laptop computer programming. Mean patient age was 68 years; 18 patients had AV block, six had sinus node dysfunction (one with AV block), nine had carotid sinus hypersensitivity (three with AV block), and two had vagally mediated syncope. At hospital discharge, programming was DDD with a mean low rate of 60 (50-70) beats/min, mean high rate of 126 (120-154) beats/min; AVDR was ON in 21 patients, rate smoothing ON in six patients, fallback ON in six patients, and PMT reprogramming algorithm ON in 27 patients. Pacemaker follow-up involved 500 clinic visits over 14.3 months (1-36). Three patients developed atrial fibrillation, reprogrammed to DDI mode (two patients) or fallback (one patient). Fallback was used 617 times. PMT occurred 427 times in six patients; the PMT algorithm reprogrammed AV delay and postventricular atrial refractory period (PVARP) automatically, a function unique to the Chorus. Intracardiac electrograms and autothreshold testing improved follow-up efficiency. This new dual chamber pacemaker enhances programming flexibility and improves diagnostic accuracy at follow-up. PMID:1279556

Kutalek, S P; Schuster, M M; Hessen, S E; Sheppard, R; Maquilan, M; Nydegger, C

1992-11-01

75

Unusual Treatment of Pacemaker Pocket Infection: A Case Report  

PubMed Central

Pocket infection of a cardiac device is usually treated by removing the device and re-implanting it in a new site after complete treatment of the infection. This report illustrates a complicated case of pocket infection in the wake of the implantation of a permanent pacemaker (cardiac resynchronization therapy). The patient was treated conservatively through daily irrigation and dressing, broad-spectrum antibiotics, and debridement without the device being removed; the generator was kept out of the pocket for 5 weeks and then re-implanted in the same location successfully. The method of treatment presented herein can be of value, not least in the elderly population who might experience life-threatening events following the replacement of their cardiac devices. PMID:23074594

Kazemisaeed, Ali; Moezzi, Ali; Shafiee, Akbar; Ghazanchai, Fatemeh

2010-01-01

76

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

PubMed

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

Mond, Harry G; Freitag, Gary

2014-12-01

77

[Anesthetic management for nephrectomy using a monopolar electrocautery in a patient implanted with a biventricular pacemaker].  

PubMed

A 72-year-old man implanted with a biventricular pacemaker was diagnosed pyonephrosis, and left nephrectomy was performed under general and epidural anesthesia. Urologists were going to use a monopolar electrocautery during the operation. Before the operation, we attempted to convert the pacemaker from DDD mode to DOO mode with a precordial magnet because we wanted to know the effect of DOO mode in this patient implanted with a biventricular pacemaker and how a monopolar electrocautery interfered the biventricular pacemaker. His blood pressure and heart rate were stable during DOO mode by a precordial magnet, but the stroke volume was reduced a little. Then, we suggested surgeons the minimal use of the monopolar electrocautery. Actually, intraoperative use of the monopolar electrocautery did not interfere his pacemaker, and the operation was completed uneventfully. Recently in Japan, cardiac resynchronization therapy (CRT) becomes more common and operations in the patients implanted with biventricular pacemakers will become more frequent. The surgeons and anesthesiologists should take in mind that the monopolar electrocautery is appropriate or not depending on the individual patient. PMID:19175023

Takimoto, Kayo; Arai, Fumio; Kita, Takashi; Sasaki, Shigeta

2009-01-01

78

Electrical interference in non-competitive pacemakers.  

PubMed

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

Sowton, E; Gray, K; Preston, T

1970-09-01

79

[Clinical practice guidelines of the Spanish Society of Cardiology on pacemakers].  

PubMed

Following a brief introduction on the history and generic codification of the different cardiac stimulation methods available, the implantation techniques are described and the requisites, such as human resources, their qualifications and the materials required, which are essential in the organization of a Pacemaker Unit are discussed. The current indications for permanent cardiac stimulation are reported and are classified by sections in tales following the 1998 norms of the ACC/AHA. In another section, the indications in special situations such as hypertrophic or dilated cardiomyopathy are described. Stimulation frequency modulation with the incorporation of biodetectors in modern pacemakers or in the probes are commented upon as is atriosynchronic ventricular stimulation with a single electrode (VDD). The recent automatisms which have been implemented in the current pacemakers are discussed and the most adequate selection of the stimulation mode for each patient is analyzed and demonstrated in a table which may be easily interpreted. On establishing the recommendable protocol for undertaking the follow up of the patient with a pacemaker, the criteria accepted as replacement indicators are discussed. In a brief section some legal aspects (drivers license, informed consent) are commented upon and the possible sources of interference with the function of the system implanted, whether medical or environmental or laboral, have been analyzed more in depth. The chapter ends with a brief discussion on the survival of patients with pacemakers. PMID:10944994

Oter Rodríguez, R; Montiel, J J; Roldán Pascual, T; Bardají Ruiz, A; Molinero de Miguel, E

2000-07-01

80

Herbal, Vitamin, and Mineral Supplement Use in Patients Enrolled in a Cardiac Rehabilitation Program  

PubMed Central

PURPOSE The use of complementary and alternative medicine is common and continues to rise each year, both in the general population and among those with cardiovascular disease. While some supplements may incur risk, particularly when used concomitantly with cardiovascular medications, others have proven benefits. However, supplements such as antioxidants and many herbs can have significant interactions with cardiovascular medications. This study aimed to identify the percentage of patients enrolled in a cardiac rehabilitation program taking herbal, vitamin, and mineral supplements. METHODS Electronic and paper charts of 235 patients enrolled in a phase 3 cardiac rehabilitation program were reviewed. Their demographics, medical history, and medications were stratified in an Excel chart, using a large matrix from which data were imported into Matlab for analysis. Custom Matlab programs were created and compiled to determine variables of interest, including percentages of patients with a specific medical condition taking certain supplements. RESULTS Sixty-seven percent of patients enrolled in the cardiac rehabilitation program were taking vitamins, with or without minerals (67%, 158 of 235). Multivitamin is the most common form of supplement (51%, 119 of 235), followed by fish oil/omega-3 polyunsaturated fatty acids (27%, 64 of 235). CONCLUSION The majority of patients in a phase 3 cardiac rehabilitation program are taking some form of herbal, vitamin, or mineral supplement. Given frequent, complicated patient medication regimens, it is important to educate patients on the potential benefits as well as lack of evidence and possible dangers of supplements. PMID:22878561

Nieva, Reynaria; Safavynia, Seyed A.; Bishop, Kathy Lee; Sperling, Laurence

2015-01-01

81

Interference between mobile phones and pacemakers: a look inside.  

PubMed

In this study we analyzed the problem of electromagnetic interference (EMI) between mobile telephones and cardiac pacemakers (PM), by looking at the mechanisms by which the radiated radio frequency (RF) GSM signal may affect the pacemaker function. From a literature review on this topic, we noticed that older pacemakers had a higher rate of being affected by mobile phones when compared to newer ones. This is probably due to the fact that new generation of PM are more protected against electromagnetic field, being equipped with RF feedthrough filters incorporated to the internal PM circuitry. In some experiments conducted by our group, we found that modulated RF signals are somehow demodulated by the PM internal non-linear circuit elements, if no feedthrough assembly is incorporated inside the PM. Such demodulation phenomenon poses a critical problem because digital cellular phones use extremely low-frequency modulation (as low as 2 Hz), that can be mistaken for normal heartbeat. The feedthrough assembly seems instead to prevents the RF signals from accessing the PM enclosure, thus attenuating EMI signals over a broad range of frequencies. PMID:17938456

Censi, Federica; Calcagnini, Giovanni; Triventi, Michele; Mattei, Eugenio; Bartolini, Pietro

2007-01-01

82

T-type channels in the sino-atrial and atrioventricular pacemaker mechanism.  

PubMed

Cardiac automaticity is a fundamental physiological function in vertebrates. Heart rate is under the control of several neurotransmitters and hormones and is permanently adjusted by the autonomic nervous system to match the physiological demand of the organism. Several classes of ion channels and proteins involved in intracellular Ca(2+) handling contribute to pacemaker activity. Voltage-dependent T-type Ca(2+) channels are an integral part of the complex mechanism underlying pacemaking. T-type channels also contribute to impulse conduction in mice and humans. Strikingly, T-type channel isoforms are co-expressed in the cardiac conduction system with other ion channels that play a major role in pacemaking such as f- (HCN4) and L-type Cav1.3 channels. Pharmacologic inhibition of T-type channels reduces the spontaneous activity of isolated pacemaker myocytes of the sino-atrial node, the dominant heart rhythmogenic centre. Target inactivation of T-type Cav3.1 channels abolishes I Ca,T in both sino-atrial and atrioventricular myocytes and reduces the daily heart rate of freely moving mice. Cav3.1 channels contribute also to automaticity of the atrioventricular node and to ventricular escape rhythms, thereby stressing the importance of these channels in automaticity of the whole cardiac conduction system. Accordingly, loss-of-function of Cav3.1 channels contributes to severe form of congenital bradycardia and atrioventricular block in paediatric patients. PMID:24573175

Mesirca, Pietro; Torrente, Angelo G; Mangoni, Matteo E

2014-04-01

83

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

ERIC Educational Resources Information Center

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)

Jenny, Ng Yuen Yee; Fai, Tam Sing

2001-01-01

84

Reconstruction of Hyman's second pacemaker.  

PubMed

Though journal articles and newspaper reports suggest that three Hyman pacemakers existed or were intended; a patent, descriptive photographs and a written description of an earlier model and only a photograph of a later model exist. A replica of the earlier has been made based on the patent and description, and a new replica of the second based on a critical deconstruction and analysis of the photograph of the second with a modern circuit duplicating the function of the earlier circuit. Both replicas were "operational" in that stimuli were mimicked though not delivered and neither could under any circumstances actually resuscitate the heart. The design and construction of the second Hyman pacemaker are presented. PMID:15869680

Furman, Seymour; Szarka, George; Layvand, Dmitriy

2005-05-01

85

21 CFR 870.1750 - External programmable pacemaker pulse generator.  

...External programmable pacemaker pulse generator. 870.1750 Section 870.1750...External programmable pacemaker pulse generator. (a) Identification. An external programmable pacemaker pulse generators is a device that can be...

2014-04-01

86

21 CFR 870.3640 - Indirect pacemaker generator function analyzer.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Indirect pacemaker generator function analyzer. 870.3640...870.3640 Indirect pacemaker generator function analyzer. (a) Identification. An indirect pacemaker generator function analyzer is an...

2013-04-01

87

21 CFR 870.3610 - Implantable pacemaker pulse generator.  

Code of Federal Regulations, 2013 CFR

...false Implantable pacemaker pulse generator. 870.3610 Section 870.3610...3610 Implantable pacemaker pulse generator. (a) Identification. An implantable pacemaker pulse generator is a device that has a...

2013-04-01

88

21 CFR 870.3630 - Pacemaker generator function analyzer.  

Code of Federal Regulations, 2011 CFR

... 2011-04-01 false Pacemaker generator function analyzer. 870.3630 ...Prosthetic Devices § 870.3630 Pacemaker generator function analyzer. (a) Identification. A pacemaker generator function analyzer is a device...

2011-04-01

89

21 CFR 870.3630 - Pacemaker generator function analyzer.  

Code of Federal Regulations, 2013 CFR

... 2013-04-01 false Pacemaker generator function analyzer. 870.3630 ...Prosthetic Devices § 870.3630 Pacemaker generator function analyzer. (a) Identification. A pacemaker generator function analyzer is a device...

2013-04-01

90

21 CFR 870.3630 - Pacemaker generator function analyzer.  

Code of Federal Regulations, 2012 CFR

... 2012-04-01 false Pacemaker generator function analyzer. 870.3630 ...Prosthetic Devices § 870.3630 Pacemaker generator function analyzer. (a) Identification. A pacemaker generator function analyzer is a device...

2012-04-01

91

21 CFR 870.1750 - External programmable pacemaker pulse generator.  

Code of Federal Regulations, 2013 CFR

...External programmable pacemaker pulse generator. 870.1750 Section 870.1750...External programmable pacemaker pulse generator. (a) Identification. An external programmable pacemaker pulse generators is a device that can be...

2013-04-01

92

21 CFR 870.3600 - External pacemaker pulse generator.  

...2014-04-01 false External pacemaker pulse generator. 870.3600 Section 870.3600...870.3600 External pacemaker pulse generator. (a) Identification. An external pacemaker pulse generator is a device that has a...

2014-04-01

93

21 CFR 870.3630 - Pacemaker generator function analyzer.  

... 2014-04-01 false Pacemaker generator function analyzer. 870.3630 ...Prosthetic Devices § 870.3630 Pacemaker generator function analyzer. (a) Identification. A pacemaker generator function analyzer is a device...

2014-04-01

94

21 CFR 870.3600 - External pacemaker pulse generator.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 false External pacemaker pulse generator. 870.3600 Section 870.3600...870.3600 External pacemaker pulse generator. (a) Identification. An external pacemaker pulse generator is a device that has a...

2012-04-01

95

21 CFR 870.3640 - Indirect pacemaker generator function analyzer.  

...2014-04-01 false Indirect pacemaker generator function analyzer. 870.3640...870.3640 Indirect pacemaker generator function analyzer. (a) Identification. An indirect pacemaker generator function analyzer is an...

2014-04-01

96

21 CFR 870.3600 - External pacemaker pulse generator.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false External pacemaker pulse generator. 870.3600 Section 870.3600...870.3600 External pacemaker pulse generator. (a) Identification. An external pacemaker pulse generator is a device that has a...

2013-04-01

97

21 CFR 870.3650 - Pacemaker polymeric mesh bag.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Pacemaker polymeric mesh bag. 870.3650 Section 870.3650 Food... § 870.3650 Pacemaker polymeric mesh bag. (a) Identification. A pacemaker polymeric mesh bag is an implanted device used to hold a...

2010-04-01

98

21 CFR 870.3650 - Pacemaker polymeric mesh bag.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 false Pacemaker polymeric mesh bag. 870.3650 Section 870.3650 Food... § 870.3650 Pacemaker polymeric mesh bag. (a) Identification. A pacemaker polymeric mesh bag is an implanted device used to hold a...

2011-04-01

99

21 CFR 870.3650 - Pacemaker polymeric mesh bag.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Pacemaker polymeric mesh bag. 870.3650 Section 870.3650 Food... § 870.3650 Pacemaker polymeric mesh bag. (a) Identification. A pacemaker polymeric mesh bag is an implanted device used to hold a...

2013-04-01

100

21 CFR 870.3650 - Pacemaker polymeric mesh bag.  

...2014-04-01 false Pacemaker polymeric mesh bag. 870.3650 Section 870.3650 Food... § 870.3650 Pacemaker polymeric mesh bag. (a) Identification. A pacemaker polymeric mesh bag is an implanted device used to hold a...

2014-04-01

101

21 CFR 870.3650 - Pacemaker polymeric mesh bag.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 false Pacemaker polymeric mesh bag. 870.3650 Section 870.3650 Food... § 870.3650 Pacemaker polymeric mesh bag. (a) Identification. A pacemaker polymeric mesh bag is an implanted device used to hold a...

2012-04-01

102

21 CFR 870.3690 - Pacemaker test magnet.  

... 2014-04-01 false Pacemaker test magnet. 870.3690 Section 870.3690 Food...Prosthetic Devices § 870.3690 Pacemaker test magnet. (a) Identification. A pacemaker test magnet is a device used to test an...

2014-04-01

103

21 CFR 870.3690 - Pacemaker test magnet.  

Code of Federal Regulations, 2012 CFR

... 2012-04-01 false Pacemaker test magnet. 870.3690 Section 870.3690 Food...Prosthetic Devices § 870.3690 Pacemaker test magnet. (a) Identification. A pacemaker test magnet is a device used to test an...

2012-04-01

104

21 CFR 870.3690 - Pacemaker test magnet.  

Code of Federal Regulations, 2013 CFR

... 2013-04-01 false Pacemaker test magnet. 870.3690 Section 870.3690 Food...Prosthetic Devices § 870.3690 Pacemaker test magnet. (a) Identification. A pacemaker test magnet is a device used to test an...

2013-04-01

105

21 CFR 870.3700 - Pacemaker programmers.  

...FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3700 Pacemaker programmers. (a) Identification. A...

2014-04-01

106

21 CFR 870.3700 - Pacemaker programmers.  

Code of Federal Regulations, 2013 CFR

...FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3700 Pacemaker programmers. (a) Identification. A...

2013-04-01

107

Disappearance of orthostatic hypotension after pacemaker implantation in a patient with a long PR interval  

PubMed Central

Orthostatic hypotension is the fall in blood pressure when upright and has a high prevalence in elderly population. Diagnostic and therapeutic work-up can be long and difficult. We describe the case of an 81-year-old male patient with long PR interval and episodes of 2:1 atrioventricular block, in whom the implantation of a dual chamber pacemaker led to the disappearance of orthostatic hypotension. The most likely mechanism was an impaired cardiac filling with a short diastolic time due to a very prolonged PR interval, a somewhat "pseudo-pacemaker syndrome". The correction of the first degree AV block with the implantation of the pacemaker and the optimization of the AV delay allowed us to correct the diastolic impairment and to resume a normal response to orthostatism. This case underlies the complex and multifactorial nature of orthostatic hypotension and the importance of a correct diagnosis of correctable causes to treat a very disabling condition. PMID:23438622

De Maria, Elia; Fontana, Pier Luigi; Cappelli, Stefano

2013-01-01

108

Petascale computation performance of lightweight multiscale cardiac models using hybrid programming models.  

PubMed

Future multiscale and multiphysics models must use the power of high performance computing (HPC) systems to enable research into human disease, translational medical science, and treatment. Previously we showed that computationally efficient multiscale models will require the use of sophisticated hybrid programming models, mixing distributed message passing processes (e.g. the message passing interface (MPI)) with multithreading (e.g. OpenMP, POSIX pthreads). The objective of this work is to compare the performance of such hybrid programming models when applied to the simulation of a lightweight multiscale cardiac model. Our results show that the hybrid models do not perform favourably when compared to an implementation using only MPI which is in contrast to our results using complex physiological models. Thus, with regards to lightweight multiscale cardiac models, the user may not need to increase programming complexity by using a hybrid programming approach. However, considering that model complexity will increase as well as the HPC system size in both node count and number of cores per node, it is still foreseeable that we will achieve faster than real time multiscale cardiac simulations on these systems using hybrid programming models. PMID:22254341

Pope, Bernard J; Fitch, Blake G; Pitman, Michael C; Rice, John J; Reumann, Matthias

2011-01-01

109

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

PubMed Central

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

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

2014-01-01

110

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

PubMed

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

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

2012-01-01

111

Multi Site Cardiac Rehabilitation Programming for Residents of Northwestern Ontario  

Microsoft Academic Search

Northwestern Ontario (NWO), Canada is a geographical region with a landmass equivalent to the country of France. The region is comprised of approximately 250,000 residents with 50% residing in sparsely populated rural areas, each challenged by limited professional resources to provide health-based programs for their residents. In 2003, the Northwestern Ontario District Health Council (NWODHC) identified inequities in the delivery

Gwen Third; Lori Marshall; Caterina Kmill; Catherine Collinson; Laurie Sherrington; Darlene Steven

2009-01-01

112

MGH West Cardiac Wellness Program Optimizing Health and Enhancing Resiliency  

E-print Network

activity. · An individualized nutrition plan to help you prepare healthy foods and maintain a heart-healthy diet, assist in weight management and improve glucose and cholesterol levels · A comprehensive stress. This program is offered at our MGH West location in Waltham. It is covered by most insurance plans

Mootha, Vamsi K.

113

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

PubMed

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

Steklov, V I

2014-01-01

114

Electrophysiological and haemodynamic basis for application of new pacemaker technology in sick sinus syndrome and atrioventricular block  

Microsoft Academic Search

A fundamental description of pacemaker systems which are commercially available or in clinical validation is given as a background for their application in a series of 62 consecutive patients presenting over a period of 1 year for permanent cardiac pacing. The patients (23 (37%) sick sinus syndrome, 38 (61%) atrioventricular block, and 1 ventricular tachycardia) were studied electrophysiologically and haemodynamically

R Sutton; P Citron

1979-01-01

115

Pacemaker Component Allergy: Case Report and Review of the Literature  

Microsoft Academic Search

Pacemaker component allergy is a relatively uncommon cause of erythema and pain at the site of an implanted pacemaker. Allergies to multiple pacemaker components have been well described. We present a case in which 2 component allergies were documented on separate occasions. Although attempts were made to protect the patient by “coating” the pacemaker, the protective coating was incomplete and

David L. Hayes; Kathy Loesl

2002-01-01

116

Managing pacemaker-related complications and malfunctions in the emergency department.  

PubMed

The use of implanted pacemaker devices is increasing worldwide, owing to technological advances, new indications, and an aging population. Despite greater experience in implantation and improved device sophistication, patients continue to face complications associated with hardware implantation and device malfunction. This review summarizes current indications for permanent pacing, reviews epidemiologic data relevant to implant complications, and describes a clinical approach to the patient with potential pacing malfunction. The electrocardiographic diagnosis of hyperkalemia and acute myocardial infarction in paced rhythms is also discussed. Potential sources of electromagnetic interference and special considerations pertaining to the cardiac resuscitation of patients with implanted cardiac devices are reviewed. Finally, a basic approach to implanted cardioverter-defibrillator devices (which often accompany pacemaker devices) is presented. PMID:25513039

Martindale, Jennifer; deSouza, S

2014-09-01

117

Managing pacemaker-related complications and malfunctions in the emergency department.  

PubMed

The use of implanted pacemaker devices is increasing worldwide, owing to technological advances, new indications, and an aging population. Despite greater experience in implantation and improved device sophistication, patients continue to face complications associated with hardware implantation and device malfunction. This review summarizes current indications for permanent pacing, reviews epidemiologic data relevant to implant complications, and describes a clinical approach to the patient with potential pacing malfunction. The electrocardiographic diagnosis of hyperkalemia and acute myocardial infarction in paced rhythms is also discussed. Potential sources of electromagnetic interference and special considerations pertaining to the cardiac resuscitation of patients with implanted cardiac devices are reviewed. Finally, a basic approach to implanted cardioverter-defibrillator devices (which often accompany pacemaker devices) is presented. PMID:25436255

Martindale, Jennifer; deSouza, S

2014-09-01

118

Pacemakers charging using body energy  

PubMed Central

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

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

2010-01-01

119

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

PubMed

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

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

2014-07-01

120

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

PubMed

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

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

2014-10-01

121

Prenatal hypoxia programs changes in ?-adrenergic signaling and postnatal cardiac contractile dysfunction.  

PubMed

Prenatal hypoxia leads to an increased risk of adult cardiovascular disease. We have previously demonstrated a programming effect of prenatal hypoxia on the cardiac ?-adrenergic (?AR) response. The aim of this study was to determine 1) whether the decrease in ?AR sensitivity in prenatally hypoxic 5-wk old chicken hearts is linked to changes in ?1AR/?2ARs, G?i expression and cAMP accumulation and 2) whether prenatal hypoxia has an effect on heart function in vivo. We incubated eggs in normoxia (N, 21% O2) or hypoxia from day 0 (H, 14% O2) and raised the posthatchlings to 5 wk of age. Cardiac ?1AR/?2ARs were assessed through competitive binding of [(3)H]CGP-12177 with specific ?1AR or ?2AR blockers. G?s and G?i proteins were assessed by Western blot and cAMP accumulation by ELISA. Echocardiograms were recorded in anesthetized birds to evaluate diastolic/systolic diameter and heart rate and tissue sections were stained for collagen. We found an increase in relative heart mass, ?1ARs, and G?s in prenatally hypoxic hearts. cAMP levels after isoproterenol stimulation and collagen content was not changed in H compared with N, but in vivo echocardiograms showed systolic contractile dysfunction. The changes in ?AR and G protein subtypes may be indicative of an early compensatory stage in the progression of cardiac dysfunction, further supported by the cardiac hypertrophy and systolic contractile dysfunction. We suggest that it is not the changes in the proximal part of the ?AR system that causes the decreased cardiac contractility, but Ca(2+) handling mechanisms further downstream in the ?AR signaling cascade. PMID:24089370

Lindgren, I; Altimiras, J

2013-11-15

122

Pacemakers  

MedlinePLUS Videos and Cool Tools

... for your specific condition. ©1995-2013, The Patient Education Institute, Inc. [www.X-Plain.com] ct150109 Last ... for your specific condition. ©1995-2013, The Patient Education Institute, Inc. [www.X-Plain.com] ct150109 Last ...

123

Effectiveness of implantation of a subcutaneous implantable cardioverter-defibrillator in a patient with complete heart block and a pacemaker.  

PubMed

The subcutaneous implantable cardioverter-defibrillator (S-ICD) represents an important alternative to traditional ICD therapy. The major limitation of this technology is the inability to provide pacing. Here, we present a case of a patient with complete heart block and a pacemaker who underwent placement of an S-ICD. Special considerations had to be taken with regards to evaluation and implantation of the S-ICD because of the pacemaker. In conclusion, implantation of an S-ICD can be done in patients with pacemaker effectively with appropriate electrocardiographic screening, device testing, and programming. PMID:25465940

Porterfield, Christopher; DiMarco, John P; Mason, Pamela K

2015-01-15

124

Changing trends in pacemaker and implantable cardioverter defibrillator generator advisories.  

PubMed

Pacemaker and implantable cardioverter defibrillator (ICD) generator recalls and safety alerts (advisories) occur frequently, affect many patients, and are increasing in number and rate. It is unknown if advances in device technology have been accompanied by changing patterns of device advisory type. Weekly FDA Enforcement Reports from January 1991 to December 2000 were analyzed to identify all advisories involving pacemaker and ICD generators. This article represents additional analysis of previously cited advisories and does not contain additional recalls or safety alerts over those that have been previously reported. The 29 advisories (affecting 159,061 devices) from the early 1990s (1991-1995) were compared to the 23 advisories (affecting 364,084 devices) from the late 1990s (1996-2000). While the annual number of device advisories did not change significantly, ICD advisories became more frequent and a three-fold increase in the number of devices affected per advisory was observed. The number of devices affected by hardware advisories increased three-fold, due primarily to a 700-fold increase in electrical/circuitry abnormalities and a 20-fold increase in potential battery/capacitor malfunctions. Other types of hardware abnormalities (defects in the device header, hermetic seal, etc.) became less common. The number of devices recalled due to firmware (computer programming) abnormalities more than doubled. The remarkable technological advances in pacemaker and ICD therapy have been accompanied by changing patterns of device advisory type. Accurate, timely physician and patient notification systems, and routine pacemaker and ICD patient follow-up continue to be of paramount importance. PMID:12520666

Maisel, William H; Stevenson, William G; Epstein, Laurence M

2002-12-01

125

Deactivation of Pacemakers and Implantable Cardioverter-Defibrillators  

PubMed Central

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

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

2013-01-01

126

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

PubMed Central

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

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

127

Adoption of community-based cardiac rehabilitation programs and physical activity following phase III cardiac rehabilitation in Scotland: A prospective and predictive study  

Microsoft Academic Search

Little is known about levels of physical activity and attendance at phase IV community-based Cardiac Rehabilitation (CR) programs following completion of exercise-focussed, hospital-based phase III CR. This study aims to test, compare and combine the predictive utility of the Common-Sense Self-Regulation Model (CS-SRM) and the extended Theory of Planned Behaviour (TPB) with action planning for two rehabilitation behaviours: physical activity

Falko F. Sniehotta; Charlotta Gorski; Vera Araújo-Soares

2010-01-01

128

Funny channels in the control of cardiac rhythm and mode of action of selective blockers  

Microsoft Academic Search

“Funny” (f) channels underlie the cardiacpacemaker”If current, originally described as an inward current activated on hyperpolarization to the diastolic range of voltages in sino-atrial node myocytes [Brown, HF, DiFrancesco, D, Noble, SJ. How does adrenaline accelerate the heart? Nature 1979;280:235–236]. The involvement of funny channels in the generation and modulation of cardiac pacemaker activity has been amply demonstrated by

Dario DiFrancesco

2006-01-01

129

An Injury-Responsive Gata4 Program Shapes the Zebrafish Cardiac Ventricle  

PubMed Central

Summary A common principle of tissue regeneration is the reactivation of previously employed developmental programs [1–3]. During zebrafish heart regeneration, cardiomyocytes in the cortical layer of the ventricle induce the transcription factor gene gata4 and proliferate to restore lost muscle [4–6]. A dynamic cellular mechanism initially creates this cortical muscle in juvenile zebrafish, where a small number of internal cardiomyocytes breach the ventricular wall and expand upon its surface [7]. Here, we find that emergent juvenile cortical cardiomyocytes induce expression of gata4 similarly as during regeneration. Clonal analysis indicates that these cardiomyocytes make biased contributions to build the ventricular wall, whereas gata4+ cardiomyocytes have little or no proliferation hierarchy during regeneration. Experimental microinjuries or conditions of rapid organismal growth stimulate production of ectopic gata4+ cortical muscle, implicating biomechanical stress in morphogenesis of this tissue and revealing clonal plasticity. Induced transgenic inhibition defined an essential role for Gata4 activity in morphogenesis of the cortical layer and the preservation of normal cardiac function in growing juveniles, and again in adults during heart regeneration. Our experiments uncover an injury-responsive program that prevents heart failure in juveniles by fortifying the ventricular wall, one that is reiterated in adults to promote regeneration after cardiac damage. PMID:23791730

Gupta, Vikas; Gemberling, Matthew; Karra, Ravi; Rosenfeld, Gabriel E.; Evans, Todd; Poss, Kenneth D.

2013-01-01

130

Cardiac resynchronization therapy: Dire need for targeted left ventricular lead placement and optimal device programming  

PubMed Central

Cardiac resynchronization therapy (CRT) effected via biventricular pacing has been established as prime therapy for heart failure patients of New York Heart Association functional class II, III and ambulatory IV, reduced left ventricular (LV) function, and a widened QRS complex. CRT has been shown to improve symptoms, LV function, hospitalization rates, and survival. In order to maximize the benefit from CRT and reduce the number of non-responders, consideration should be given to target the optimal site for LV lead implantation away from myocardial scar and close to the latest LV site activation; and also to appropriately program the device paying particular attention to optimal atrioventricular and interventricular intervals. We herein review current data related to both optimal LV lead placement and device programming and their effects on CRT clinical outcomes. PMID:25548617

Pastromas, Sokratis; Manolis, Antonis S

2014-01-01

131

Radiology of cardiac devices and their complications.  

PubMed

This article familiarizes the reader with several different cardiac devices including pacemakers and implantable cardioverter defibrillators, intra-aortic balloon pumps, ventricular assist devices, valve replacements and repairs, shunt-occluding devices and passive constraint devices. Many cardiac devices are routinely encountered in clinical practice. Other devices are in the early stages of development, but circumstances suggest that they too will become commonly found. The radiologist must be familiar with these devices and their complications. PMID:25411826

Dipoce, J; Bernheim, A; Spindola-Franco, H

2015-02-01

132

The effectiveness of rigid pericardial endoscopy for minimally invasive minor surgeries: cell transplantation, epicardial pacemaker lead implantation, and epicardial ablation  

PubMed Central

Background The efficacy and safety of rigid pericardial endoscopy as the promising minimally invasive approach to the pericardial space was evaluated. Techniques for cell transplantation, epicardial pacemaker lead implantation, and epicardial ablation were developed. Methods Two swine and 5 canines were studied to evaluate the safety and efficacy of rigid pericardial endoscopy. After a double pericardiocentesis, a transurethral rigid endoscope was inserted into the pericardial space. The technique to obtain a clear visual field was examined, and acute complications such as hemodynamic changes and the effects on intra-pericardial pressure were evaluated. Using custom-made needles, pacemaker leads, and forceps, the applications for cell transplantation, epicardial pacemaker lead implantation, and epicardial ablation were also evaluated. Results The use of air, the detention of a stiff guide wire in the pericardial space, and the stretching of the pericardium with the rigid endoscope were all useful to obtain a clear visual field. A side-lying position also aided observation of the posterior side of the heart. As a cell transplantation methodology, we developed an ultrasonography-guided needle, which allows for the safe visualization of transplantation without major complications. Pacemaker leads were safely and properly implanted, which provides a better outcome for cardiac resynchronizing therapy. Furthermore, the success of clear visualization of the pulmonary veins enabled us to perform epicardial ablation. Conclusions Rigid pericardial endoscopy holds promise as a safe method for minimally invasive cell transplantation, epicardial pacemaker lead implantation, and epicardial ablation by allowing clear visualization of the pericardial space. PMID:23140449

2012-01-01

133

Pacemaker in complicated and refractory breath-holding spells: When to think about it?  

PubMed

Background: Breath-holding spells (BHS) are benign non-epileptic paroxysmal events of infancy, rarely occurring with high frequency and complicated by prolonged syncope, convulsions and even status epilepticus. In these cases response to medical treatment is often unsatisfactory. Pacemaker implantation is a possible therapeutic option, but its indications, efficacy and complications have not been clarified yet. Objective: To report a new case of BHS treated with pacemaker and to review its indications and efficacy in patients with severe BHS. Methods: We extensively searched the literature in PubMed on cardiac pacing in patients with BHS and we described a new case. Results: A previously healthy boy presented at the age of 4months with frequent BHS inconstantly associated to prolonged syncope and post-anoxic non-epileptic and epileptic seizures. Parental reassurance, iron supplementation and piracetam were ineffective. After cardiac pacing at the age of 16months, BHS and their complications disappeared. We identified 47 patients with BHS treated with pacemaker in the literature. Based on the available data, in all patients asystole or marked bradycardia were documented during BHS or stimulating maneuvers; syncope complicated BHS in 100% of cases and post-anoxic convulsions in 78.3%. Medical treatment before pacing, when administered, was ineffective or poorly tolerated. After pacing, BHS complications disappeared in 86.4% of cases, and decreased in 13.6%. Technical problems with the device were reported in 25.7% of patients and mild medical complications in 11.4%. Conclusions: Pacemaker could be reasonably considered in subjects with frequent and severe BHS, poor response to medications, and demonstration of cardioinhibition during spells. PMID:24630493

Sartori, Stefano; Nosadini, Margherita; Leoni, Loira; de Palma, Luca; Toldo, Irene; Milanesi, Ornella; Cerutti, Alessia; Suppiej, Agnese

2015-01-01

134

Sleep Syncope: Treatment with a Permanent Pacemaker  

PubMed Central

Vasovagal syncope usually occurs during upright posture, but Jardine et al. have described a variant that occurs at night. During “sleep syncope”, patients are awakened from sleep with nausea, abdominal cramping or a sense of impending diarrhea, get up, and faint in the bathroom. We report on a patient with recurrent sleep syncope (with physical injury) in whom an asystolic pause was documented during one of her “sleep syncope” spells. Implantation of a dual chamber pacemaker (5 year follow-up) “cured” her of further syncope. This is the 1st report of pacemaker use for this unusual form of reflex syncope. PMID:22433038

Rytlewski, Jason A.; Lee, John T.; Raj, Satish R.

2013-01-01

135

Prenatal Diagnosis of Fetal Complete Atrioventricular Block with QT Prolongation and Alternating Ventricular Pacemakers Using MultiChannel Magnetocardiography and Current-Arrow Maps  

Microsoft Academic Search

We report a case of fetal complete atrioventricular block (CAVB) with QT prolongation and alternating ventricular pacemakers diagnosed by magentocardiography (MCG). Fetal bradyarrhythmia of around 60 bpm was detected at 30 weeks of gestation. Ultrasonography revealed fetal CAVB without structural cardiac anomalies. MCG was recorded at 30 weeks of gestation using a 64-channel superconducting quantum interference device (MC-6400, Hitachi, Japan).

Takayoshi Hosono; Mika Shinto; Yoshihide Chiba; Akihiko Kandori; Keiji Tsukada

2002-01-01

136

Cardiac rehabilitation outcomes following a 6-week program of PCI and CABG Patients  

PubMed Central

Coronary artery events requiring intervention are associated with depressed cardiac autonomic function. Whether a 6-week cardiac rehabilitation (CR) differs in effectiveness in improving exercise capacity (6MWT), cardiorespiratory function (peakVO2), and autonomic function (HRV) following either cardiac bypass surgery (CABG) or percutaneous coronary revascularization (PCI) is unknown. The current study therefore compared the change in 6MWT and peak VO2 to HRV variables following a 6-week CR program and with patients having either PCI or CABG. Thirty-eight patients, (PCI, n = 22 and CABG, n = 16) participated in the CR program and results for pre and post 6 min walk test (6MWT), peakVO2, and heart rate variability (HRV) were obtained. Our study has shown that a 6 weeks program following either PCI or CABG improves function. However, the effect on post-CABG differs to that of post-PCI patients. The change in distance walked (6MWT, metres) was higher in the CABG (?6MWT: 61, p < 0.001) compared to the PCI group (?6MWT: 41, p < 0.001). Maximum exercise capacity (peak VO2, ml/kg.min) also changed significantly with a greater change in the CABG group (?PCI: 0.7, p < 0.001; ?CABG: 1.0, p < 0.001) but did not reach normal population values. Although an improvement in HRV parameters was noted for the PCI group, a statistically significant improvement in HRV was observed only in the CABG group for the following; SDNN (ms) (baseline vs. post-rehabilitation (median ± IQR): 31.2 ± 25.6 vs. 51.8 ± 23.1, p < 0.01), RMSSD (19.32 ± 19.9 vs. 42.1 ± 34.2, p < 0.01); LF (ms2) (191 ± 216 vs. 631 ± 693, p < 0.01) and HF (107 ± 201 vs. 449 ± 795.0, p < 0.05). A significant interaction in the PCI group but not in the CABG group was observed using correlation analysis between the 6MWT and peak VO2 with HRV parameters indicating that being healthier that is, a better 6MWT and peak VO2 led to better HRV results but no significant effect of CR in the PCI group. When the results were investigated for baseline 6MWT and peak VO2 effect using a covariate analysis, a significant influence of CR on HRV parameters was retained in the CABG group (p = 0.0072). Our study indicates that a 6-weeks CR program benefits both patient groups in terms of exercise capacity, cardiorespiratory function and autonomic nervous system modulation of heart rate, with CABG patients showing the most improvement. HRV can be a useful additional variable to gauge cardiac function following CR. PMID:24198786

Jelinek, Herbert F.; Huang, Zhaoqi Q.; Khandoker, Ahsan H.; Chang, Dennis; Kiat, Hosen

2013-01-01

137

Cardiac rehabilitation outcomes following a 6-week program of PCI and CABG Patients.  

PubMed

Coronary artery events requiring intervention are associated with depressed cardiac autonomic function. Whether a 6-week cardiac rehabilitation (CR) differs in effectiveness in improving exercise capacity (6MWT), cardiorespiratory function (peakVO2), and autonomic function (HRV) following either cardiac bypass surgery (CABG) or percutaneous coronary revascularization (PCI) is unknown. The current study therefore compared the change in 6MWT and peak VO2 to HRV variables following a 6-week CR program and with patients having either PCI or CABG. Thirty-eight patients, (PCI, n = 22 and CABG, n = 16) participated in the CR program and results for pre and post 6 min walk test (6MWT), peakVO2, and heart rate variability (HRV) were obtained. Our study has shown that a 6 weeks program following either PCI or CABG improves function. However, the effect on post-CABG differs to that of post-PCI patients. The change in distance walked (6MWT, metres) was higher in the CABG (?6MWT: 61, p < 0.001) compared to the PCI group (?6MWT: 41, p < 0.001). Maximum exercise capacity (peak VO2, ml/kg.min) also changed significantly with a greater change in the CABG group (?PCI: 0.7, p < 0.001; ?CABG: 1.0, p < 0.001) but did not reach normal population values. Although an improvement in HRV parameters was noted for the PCI group, a statistically significant improvement in HRV was observed only in the CABG group for the following; SDNN (ms) (baseline vs. post-rehabilitation (median ± IQR): 31.2 ± 25.6 vs. 51.8 ± 23.1, p < 0.01), RMSSD (19.32 ± 19.9 vs. 42.1 ± 34.2, p < 0.01); LF (ms(2)) (191 ± 216 vs. 631 ± 693, p < 0.01) and HF (107 ± 201 vs. 449 ± 795.0, p < 0.05). A significant interaction in the PCI group but not in the CABG group was observed using correlation analysis between the 6MWT and peak VO2 with HRV parameters indicating that being healthier that is, a better 6MWT and peak VO2 led to better HRV results but no significant effect of CR in the PCI group. When the results were investigated for baseline 6MWT and peak VO2 effect using a covariate analysis, a significant influence of CR on HRV parameters was retained in the CABG group (p = 0.0072). Our study indicates that a 6-weeks CR program benefits both patient groups in terms of exercise capacity, cardiorespiratory function and autonomic nervous system modulation of heart rate, with CABG patients showing the most improvement. HRV can be a useful additional variable to gauge cardiac function following CR. PMID:24198786

Jelinek, Herbert F; Huang, Zhaoqi Q; Khandoker, Ahsan H; Chang, Dennis; Kiat, Hosen

2013-01-01

138

Gold-coated pacemaker implantation after allergic reactions to pacemaker compounds.  

PubMed

An 86-year-old man underwent pacemaker implantation for symptomatic atrio-ventricular block grade 2 Mobitz II. The patient suffered repeated admissions for iterative sterile wound necrosis, leading to two generator re-implantations. No bacterial infection was detected in the microbiological screening tests. The skin patch testing to titanium was negative. Nevertheless, we decided to remove the pacemaker system and to implant a gold-plated generator with polyurethane leads. Since then, there has been no recurrence of wound complications. Gold-plated generator and polyurethane leads are effective in treating allergic reactions to pacemaker system components in selected cases. Negative skin patch testing to titanium does not exclude allergic reaction to this pacemaker component. PMID:20022879

Syburra, Thomas; Schurr, Ulrich; Rahn, Mariette; Graves, Kirk; Genoni, Michele

2010-05-01

139

Predictive factors for pacemaker requirement after transcatheter aortic valve implantation  

PubMed Central

Background Transcatheter aortic valve implantation (TAVI) has been established as a treatment option for inoperable patients with symptomatic aortic valve stenosis. However, patients suffer frequently from conduction disturbances after TAVI. Methods Baseline, procedural as well as surface and intracardiac ECG parameters were evaluated for patients treated with TAVI and a comparison between patients requiring pacemaker with those not suffering from relevant conduction disorders were done. Results TAVI was successfully in all patients (n=45). Baseline surface and intracardiac ECG recording revealed longer PQ (197.1±51.2 msec versus 154.1±32.1 msec; p<0.001), longer AH (153.6±43.4 msec versus 116.1±31.2 msec; p<0.001) and HV interval (81.7±17.8 msec versus 56.8±8.5 msec; p<0.001) in patients with need for a pacemaker (n=23) versus control group (n=22); furthermore, 7-day follow-up analysis showed a higher prevalence of new left bundle branch block (LBBB) (87.0% versus 31.9%; p<0.001). Multivariate analysis revealed that only new LBBB, QRS duration >120 msec and a PQ interval >200 msec immediately (within 60 minutes) after implantation of the aortic valve were predictors for high-grade (type II second-degree and third-degree) AV block. Other clinical parameters as well as baseline electrocardiographic parameters had no impact on critical conduction delay. Conclusion Cardiac conduction disturbances are common after TAVI. The need for pacing after TAVI is predictable by surface ECG evaluation immediately (within 60 minutes) after the procedure. PMID:23035864

2012-01-01

140

Present day pacemakers for pulse generator exchange: is 3.5 V a sufficient nominal setting for the pulse amplitude? Thera Pacemaker Study Group.  

PubMed

Projected pacemaker longevity is calculated according to the nominal setting, which is 3.5 V for pulse amplitude in most present day pacemakers. The aim of this study was to test whether the nominal ventricular output setting of 3.5 V and 0.4 ms provides a 100% safety margin if these pacemakers are connected to implanted ventricular pacing leads. The study included 24 patients undergoing pulse generator exchange. The new pacemaker was either a Thera DR (n = 21) or Thera SR (n = 3) device. Ventricular pacing leads were implanted 70 +/- 38 months previously. Intraoperative measurements included pacing threshold at 0.5-ms pulse duration, impedance, and R wave amplitude. To achieve a 100% safety margin with 3.5 V, the cut-off pacing threshold is 1.7 V. At discharge it was assessed whether ventricular pulse amplitude remained at < or = 3.5 V or was programmed to > 3.5 V. At pulse generator exchange, pacing threshold was 1.2 +/- 0.5 V, including four patients with pacing thresholds > 1.7 V. Impedance was 587 +/- 189 omega and R wave amplitude was 12.8 +/- 4.8 mV. At discharge, ventricular pulse amplitude remained at the nominal setting in 13 patients, including 2 patients with high pacing thresholds at pacemaker exchange, and was programmed to < 3.5 V in 7 patients. Ventricular pulse amplitude was programmed to > 3.5 V in four patients. Two of these patients had high pacing thresholds (> 1.7 V/0.5 ms) at pulse generator exchange; the other two patients were programmed to > 3.5 V, although 3.5 V already provided a 100% safety margin. After pulse generator exchange, 92% of the patients could be paced with a 3.5-V pulse amplitude. Pacemakers were programmed in four patients > 3.5 V, but in only two of them to obtain a sufficient safety margin. High pacing thresholds at pulse generator exchange did not generally predict high pacing thresholds at discharge. PMID:8945049

Schuchert, A; Van Langen, H; Michels, K; Meinertz, T

1996-11-01

141

Prevention of pacemaker-associated contact dermatitis by polytetrafluoroethylene sheet and conduit coating of the pacemaker system.  

PubMed

A 73-year-old female with sick sinus syndrome and atrial fibrillation was implanted with a ventricular demand inhibit pacemaker. She subsequently developed multiple episodes of skin irritation and necrosis. Skin patch testing revealed sensitivity to almost every component of the pacemaker system. The pacemaker was removed and replaced with a new pacemaker in which the generator was covered with a polytetrafluoroethylene (PTFE) sheet and the lead was covered with PTFE conduit. The patient suffered no further episodes of pacemaker-associated contact dermatitis. PMID:24899091

Taguchi, Takahiro; Maeba, Satoru; Sueda, Taijiro

2014-09-01

142

Pacemaker neurons within newborn spinal pain circuits  

PubMed Central

Spontaneous activity driven by “pacemaker” neurons, defined by their intrinsic ability to generate rhythmic burst-firing, contributes to the development of sensory circuits in many regions of the immature CNS. However, it is unknown if pacemaker-like neurons are present within central pain pathways in the neonate. Here we provide evidence that a subpopulation of glutamatergic interneurons within lamina I of the rat spinal cord exhibits oscillatory burst-firing during early life, which occurs independently of fast synaptic transmission. Pacemaker neurons were distinguished by a higher ratio of persistent, voltage-gated Na+ conductance to leak membrane conductance (gNa,P / gleak) compared to adjacent, non-bursting lamina I neurons. The activation of high-threshold (N-type and L-type) voltage-gated Ca2+ channels also facilitated rhythmic burst-firing by triggering intracellular Ca2+ signaling. Bursting neurons received direct projections from high-threshold sensory afferents, but transmitted nociceptive signals with poor fidelity while in the bursting mode. The observation that pacemaker neurons send axon collaterals throughout the neonatal spinal cord raises the possibility that intrinsic burst-firing could provide an endogenous drive to the developing sensorimotor networks which mediate spinal pain reflexes. PMID:21677184

Li, Jie; Baccei, Mark L.

2011-01-01

143

Comparison of Cardiac Rehabilitation Programs Combined with Relaxation and Meditation Techniques on Reduction of Depression and Anxiety of Cardiovascular Patients  

PubMed Central

Cardiovascular disease (CVD) is a major cause of death in developed countries. Most cardiac rehabilitation programs include psychological interventions. The aim of this study was to determine the effectiveness of rehabilitation techniques in cardiac patients including psychological-physical interventions such as Meditation and Relaxation. We enrolled 45 patients with CVD and depression. The patients were allocated to 3 groups (Relaxation, Meditation and Control). There was a significant reduction on depression, systolic blood pressure and heart rate in the Meditation group compared with the control group. Our findings suggest that meditation techniques have better outcomes in cardiac patients for improving depression, reduction of systolic and diastolic blood pressure, and heart rate than relaxation techniques. PMID:24179555

Delui, Mahdy Hassanzadeh; Yari, Maliheh; khouyinezhad, Gholamreza; Amini, Maral; Bayazi, Mohammad Hosein

2013-01-01

144

Pacemaker failures characterized by continuous direct current leakage.  

PubMed

Pulse generator failure caused by continuous leakage of direct current through an output capacitor has not previously been appreciated. Routine post-explant electronic evaluation has identified the defect in six implanted and one external pulse generator. The constant direct current in the implantable units, 0.14 to 0.26 milliamperes, is in the range that produces ventricular arrhythmias in dogs although this did not occur in our patients. Evidence of local myocardial damage existed in four cases and of electrode deterioration in three. The implant failures occurred without warning and in four cases within 2 weeks of demonstrated normal function, blunting the predictive benefits of pacemaker monitoring programs. Capacitor discharge circuits used in many pacers are inherently capable of developing direct current leakage in the event of output capacitor short circuit. In one model of pacemakers such continuous direct current leakage caused 8.3 percent (3 of 36) of pulse generator failures, widely scattered in time at 23, 27 and 46 months after implant. Capacitor short circuit causing constant direct current leakage can masquerade as primary battery failure and should be suspected when cessation of pacer function is associated with increased threshold or poor myocardial electrogram without evidence of wire break or displacement. PMID:1274862

Fisher, J D; Furman, S; Parker, B; Escher, D J

1976-06-01

145

Performance of hybrid programming models for multiscale cardiac simulations: preparing for petascale computation.  

PubMed

Future multiscale and multiphysics models that support research into human disease, translational medical science, and treatment can utilize the power of high-performance computing (HPC) systems. We anticipate that computationally efficient multiscale models will require the use of sophisticated hybrid programming models, mixing distributed message-passing processes [e.g., the message-passing interface (MPI)] with multithreading (e.g., OpenMP, Pthreads). The objective of this study is to compare the performance of such hybrid programming models when applied to the simulation of a realistic physiological multiscale model of the heart. Our results show that the hybrid models perform favorably when compared to an implementation using only the MPI and, furthermore, that OpenMP in combination with the MPI provides a satisfactory compromise between performance and code complexity. Having the ability to use threads within MPI processes enables the sophisticated use of all processor cores for both computation and communication phases. Considering that HPC systems in 2012 will have two orders of magnitude more cores than what was used in this study, we believe that faster than real-time multiscale cardiac simulations can be achieved on these systems. PMID:21768044

Pope, Bernard J; Fitch, Blake G; Pitman, Michael C; Rice, John J; Reumann, Matthias

2011-10-01

146

Autonomic cardiac innervation  

PubMed Central

Autonomic cardiac neurons have a common origin in the neural crest but undergo distinct developmental differentiation as they mature toward their adult phenotype. Progenitor cells respond to repulsive cues during migration, followed by differentiation cues from paracrine sources that promote neurochemistry and differentiation. When autonomic axons start to innervate cardiac tissue, neurotrophic factors from vascular tissue are essential for maintenance of neurons before they reach their targets, upon which target-derived trophic factors take over final maturation, synaptic strength and postnatal survival. Although target-derived neurotrophins have a central role to play in development, alternative sources of neurotrophins may also modulate innervation. Both developing and adult sympathetic neurons express proNGF, and adult parasympathetic cardiac ganglion neurons also synthesize and release NGF. The physiological function of these “non-classical” cardiac sources of neurotrophins remains to be determined, especially in relation to autocrine/paracrine sustenance during development.   Cardiac autonomic nerves are closely spatially associated in cardiac plexuses, ganglia and pacemaker regions and so are sensitive to release of neurotransmitter, neuropeptides and trophic factors from adjacent nerves. As such, in many cardiac pathologies, it is an imbalance within the two arms of the autonomic system that is critical for disease progression. Although this crosstalk between sympathetic and parasympathetic nerves has been well established for adult nerves, it is unclear whether a degree of paracrine regulation occurs across the autonomic limbs during development. Aberrant nerve remodeling is a common occurrence in many adult cardiovascular pathologies, and the mechanisms regulating outgrowth or denervation are disparate. However, autonomic neurons display considerable plasticity in this regard with neurotrophins and inflammatory cytokines having a central regulatory function, including in possible neurotransmitter changes. Certainly, neurotrophins and cytokines regulate transcriptional factors in adult autonomic neurons that have vital differentiation roles in development. Particularly for parasympathetic cardiac ganglion neurons, additional examinations of developmental regulatory mechanisms will potentially aid in understanding attenuated parasympathetic function in a number of conditions, including heart failure. PMID:23872607

Hasan, Wohaib

2013-01-01

147

77 FR 37573 - Effective Date of Requirement for Premarket Approval for an Implantable Pacemaker Pulse Generator  

Federal Register 2010, 2011, 2012, 2013

...Approval for an Implantable Pacemaker Pulse Generator AGENCY: Food and Drug Administration...PDP) for implantable pacemaker pulse generators. The Agency has summarized its findings...PDP for the implantable pacemaker pulse generator. In accordance with section...

2012-06-22

148

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

PubMed

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

Garg, Naveen; Moorthy, Nagaraja

2012-12-01

149

21 CFR 870.3710 - Pacemaker repair or replacement material.  

Code of Federal Regulations, 2013 CFR

...FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3710 Pacemaker repair or replacement material. (a)...

2013-04-01

150

21 CFR 870.3620 - Pacemaker lead adaptor.  

...FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3620 Pacemaker lead adaptor. (a) Identification. A...

2014-04-01

151

21 CFR 870.3620 - Pacemaker lead adaptor.  

Code of Federal Regulations, 2013 CFR

...FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3620 Pacemaker lead adaptor. (a) Identification. A...

2013-04-01

152

21 CFR 870.3730 - Pacemaker service tools.  

...FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3730 Pacemaker service tools. (a) Identification....

2014-04-01

153

21 CFR 870.3720 - Pacemaker electrode function tester.  

...FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3720 Pacemaker electrode function tester. (a)...

2014-04-01

154

21 CFR 870.3730 - Pacemaker service tools.  

Code of Federal Regulations, 2013 CFR

...FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3730 Pacemaker service tools. (a) Identification....

2013-04-01

155

Peak Oxygen Uptake after Cardiac Rehabilitation: A Randomized Controlled Trial of a 12-Month Maintenance Program versus Usual Care  

PubMed Central

Background Exercise capacity is a strong predictor of survival in patients with coronary artery disease (CAD). Exercise capacity improves after cardiac rehabilitation exercise training, but previous studies have demonstrated a decline in peak oxygen uptake after ending a formal rehabilitation program. There is a lack of knowledge on how long-term exercise adherence can be achieved in CAD patients. We therefore assessed if a 12-month maintenance program following cardiac rehabilitation would lead to increased adherence to exercise and increased exercise capacity compared to usual care. Materials and Methods Two-centre, open, parallel randomized controlled trial with 12 months follow-up comparing usual care to a maintenance program. The maintenance program consisted of one monthly supervised high intensity interval training session, a written exercise program and exercise diary, and a maximum exercise test every third month during follow-up. Forty-nine patients (15 women) on optimal medical treatment were included following discharge from cardiac rehabilitation. The primary endpoint was change in peak oxygen uptake at follow-up; secondary endpoints were physical activity level, quality of life and blood markers of cardiovascular risk. Results There was no change in peak oxygen uptake from baseline to follow-up in either group (intervention group 27.9 (±4.7) to 28.8 (±5.6) mL·kg (-1) min (?1), control group 32.0 (±6.2) to 32.8 (±5.8) mL·kg (?1) min (?1), with no between-group difference, p?=?0.22). Quality of life and blood biomarkers remained essentially unchanged, and both self-reported and measured physical activity levels were similar between groups after 12 months. Conclusions A maintenance exercise program for 12 months did not improve adherence to exercise or peak oxygen uptake in CAD patients after discharge from cardiac rehabilitation compared to usual care. This suggests that infrequent supervised high intensity interval training sessions are inadequate to improve peak oxygen uptake in this patient group. Trial Registration ClinicalTrials.gov NCT01246570 PMID:25247991

Madssen, Erik; Arbo, Ingerid; Granøien, Ingrid; Walderhaug, Liv; Moholdt, Trine

2014-01-01

156

[A Corynebacterium striatum endocarditis on a carrier of pacemaker].  

PubMed

We report a new case of a Corynebacterium striatum endocarditis on a carrier of a pacemaker. Corynebacterium striatum was isolated from blood culture, the pulse generator and the pacing lead. A literature review of Corynebacterium striatum endocarditis on a carrier of pacemaker was conducted. PMID:22565181

Abi, Rachid; Ez-Zahraouii, Khalil; Ghazouani, Mohammed; Zohoun, Alban; Kheyi, Jamal; Chaib, Ali; Elouennass, Mostafa

2012-01-01

157

Pre-ejection period by radial artery tonometry supplements echo doppler findings during biventricular pacemaker optimization  

PubMed Central

Background Biventricular (Biv) pacemaker echo optimization has been shown to improve cardiac output however is not routinely used due to its complexity. We investigated the role of a simple method involving computerized pre-ejection time (PEP) assessment by radial artery tonometry in guiding Biv pacemaker optimization. Methods Blinded echo and radial artery tonometry were performed simultaneously in 37 patients, age 69.1 ± 12.8 years, left ventricular (LV) ejection fraction (EF) 33 ± 10%, during Biv pacemaker optimization. Effect of optimization on echo derived velocity time integral (VTI), ejection time (ET), myocardial performance index (MPI), radial artery tonometry derived PEP and echo-radial artery tonometry derived PEP/VTI and PEP/ET indices was evaluated. Results Significant improvement post optimization was achieved in LV ET (286.9 ± 37.3 to 299 ± 34.6 ms, p < 0.001), LV VTI (15.9 ± 4.8 cm to 18.4 ± 5.1 cm, p < 0.001) and MPI (0.57 ± 0.2 to 0.45 ± 0.13, p < 0.001) and in PEP (246.7 ± 36.1 ms to 234.7 ± 35.5 ms, p = 0.003), PEP/ET (0.88 ± 0.21 to 0.79 ± 0.17, p < 0.001), and PEP/VTI (17.3 ± 7 to 13.78 ± 4.7, p < 0.001). The correlation between comprehensive echo Doppler and radial artery tonometry-PEP guided optimal atrioventricular delay (AVD) and optimal interventricular delay (VVD) was 0.75 (p < 0.001) and 0.69 (p < 0.001) respectively. In 29 patients with follow up assessment, New York Heart Association (NYHA) class reduced from 2.5 ± 0.8 to 2.0 ± 0.9 (p = 0.004) at 1.8 ± 1.4 months. Conclusion An acute shortening of PEP by radial artery tonometry occurs post Biv pacemaker optimization and correlates with improvement in hemodynamics by echo Doppler and may provide a cost-efficient approach to assist with Biv pacemaker echo optimization. PMID:21794181

2011-01-01

158

Use of pacemaker programmers for disaster victim identification.  

PubMed

Disaster victim identification (DVI) presents a number of physical and legal challenges, involving the degeneration of human remains and legal obstacles to forensic examinations. One non-invasive method for positive identification may be the use of a pacemaker programmer to detect and obtain data from pacemakers recovered from unidentified remains. To test the usefulness of this method, this investigation examined the efficiency and utility of 5 different pacemaker programmers in the positive identification of victims of the March 2011 tsunami in Japan at 8 disaster sites in May 2011. On scanning 148 sets of remains, data were successfully obtained from 1 implant in 1 set of remains, allowing for the rapid positive identification of the individual. Scanning pacemakers with pacemaker programmers can be a non-invasive method of positive identification that meets Japanese legal and institutional requirements, but this method is ineffective without a preceding whole-body X-ray scan. PMID:23592022

Makinae, Haruka; Numata, Norio; Kitaoka, Hirofumi; Daimon, Masao; Yamamoto, Taira; Amano, Atsushi

2013-12-01

159

In-vitro mapping of E-fields induced near pacemaker leads by simulated MR gradient fields  

PubMed Central

Background Magnetic resonance imaging (MRI) of patients with implanted cardiac pacemakers is generally contraindicated but some clinicians condone scanning certain patients. We assessed the risk of inducing unintended cardiac stimulation by measuring electric fields (E) induced near lead tips by a simulated MRI gradient system. The objectives of this study are to map magnetically induced E near distal tips of leads in a saline tank to determine the spatial distribution and magnitude of E and compare them with E induced by a pacemaker pulse generator (PG). Methods We mapped magnetically induced E with 0.1 mm resolution as close as 1 mm from lead tips. We used probes with two straight electrodes (e.g. wire diameter of 0.2 mm separated by 0.9 mm). We generated magnetic flux density (B) with a Helmholtz coil throughout 0.6% saline in a 24 cm diameter tank with (dB/dt) of 1 T/sec (1 kHz sinusoidal waveform). Separately, we measured E near the tip of leads when connected to a PG set to a unipolar mode. Measurements were non-invasive (not altering the leads or PG under study). Results When scaled to 30 T/s (a clinically relevant value), magnetically-induced E exceeded the E produced by a PG. The magnetically-induced E only occurred when B was coincident with or within 15 msec of implantable pacemaker's pulse. Conclusions Potentially hazardous situations are possible during an MR scan due to gradient fields. Unintended stimulation can be induced via abandoned leads and leads connected to a pulse generator with loss of hermetic seal at the connector. Also, pacemaker-dependent patients can receive drastically altered pacing pulses. PMID:20003479

2009-01-01

160

Correlation between changes in diastolic dysfunction and health-related quality of life after cardiac rehabilitation program in dilated cardiomyopathy  

PubMed Central

Chronic heart failure (CHF) is a complex syndrome characterized by progressive decline in left ventricular function, low exercise tolerance and raised mortality and morbidity. Left ventricular diastolic dysfunction plays a major role in CHF and progression of most cardiac diseases. The current recommended goals can theoretically be accomplished via exercise and pharmacological therapy so the aim of the present study was to evaluate the impact of cardiac rehabilitation program on diastolic dysfunction and health related quality of life and to determine the correlation between changes in left ventricular diastolic dysfunction and domains of health-related quality of life (HRQoL). Forty patients with chronic heart failure were diagnosed as having dilated cardiomyopathy (DCM) with systolic and diastolic dysfunction. The patients were equally and randomly divided into training and control groups. Only 30 of them completed the study duration. The training group participated in rehabilitation program in the form of circuit-interval aerobic training adjusted according to 55–80% of heart rate reserve for a period of 7 months. Circuit training improved both diastolic and systolic dysfunction in the training group. On the other hand, only a significant correlation was found between improvement in diastolic dysfunction and health related quality of life measured by Kansas City Cardiomyopathy Questionnaire. It was concluded that improvement in diastolic dysfunction as a result of rehabilitation program is one of the important underlying mechanisms responsible for improvement in health-related quality of life in DCM patients.

Mehani, Sherin H.M.

2012-01-01

161

Clinical experience of pacemaker treatment in children.  

PubMed

Pacemaker treatment is more complicated in children than in adults, mainly because of electrode problems. A pacemaker system was implanted in 23 children aged 2 days-14 years (mean 4.8 years, with 11 less than or equal to 3 years) at the Karolinska Hospital since 1983. The indications for pacing were peroperative atrioventricular block (AVB) in 13 cases, congenital AVB in five, sinoatrial disorder in four and slow ventricular arrhythmia in one case. The initially implanted electrode was epicardial in ten children (in the first 2 years of the study) and endocardial in the other 13. Eight of the ten epicardial electrodes had to be replaced by endocardial within a mean of 2.5 years. There were 18 reoperations, the reasons being increased threshold/exit block--all epicardial leads (8 cases), electrode failure (1), 'stretching' of the electrode secondary to body growth (4), local infection (3) and generator replacement (2). The reoperation rate was unacceptably high in children with epicardial electrodes. Endocardial pacing is the method of choice even for small infants. PMID:1529301

Nordlander, R; Pehrsson, S K; Böök, K; Zetterqvist, P; Fahlén-Vepsä, I L

1992-01-01

162

Urethral stromal tumor with pacemaker cell phenotype.  

PubMed

Penile malignancies are rare in developed countries. The authors present a case of a penile urethral mesenchymal tumor occurring in a 51-year-old Caucasian male and displaying light microscopic, immunohistochemical, and ultrastructural features suggestive of a pacemaker cell type, combined with a lack of diagnostic features of any other established tumor category. The immunohistochemical profile was intensely positive for vimentin, PKC theta, and NSE and weakly positive to nonreactive for CD34 and smooth muscle actin, and entirely negative for CD117 (c-kit), S-100, and other markers. C-kit and PDGFRA gene analysis showed no mutations. Electron microscopy revealed tumor cells with plentiful cytoplasm and cytoplasmic processes/filopodia, both filled with intermediate filaments and occasional solitary focal densities. There were also prominent smooth endoplasmic reticulum cisternae, caveolae, neurosecretory granules, particularly concentrated in cytoplasmic processes, and synaptic-type structures. Poorly formed basal lamina, gap junctions, and intercellular collagen aggregates, consistent with skeinoid-type fibers, were also noted. Interstitial cells with potential pacemaker function have been recently described in the lower urinary tract, including the urethra, and this tumor may be related to this cellular phenotype. PMID:17455099

Kanner, William A; Drachenberg, Cinthia B; Papadimitriou, John C; Wang, Suna; Meltzer, Stephen J; Sklar, Geoffrey N

2007-01-01

163

Cardiac fluid dynamics anticipates heart adaptation.  

PubMed

Hemodynamic forces represent an epigenetic factor during heart development and are supposed to influence the pathology of the grown heart. Cardiac blood motion is characterized by a vortical dynamics, and it is common belief that the cardiac vortex has a role in disease progressions or regression. Here we provide a preliminary demonstration about the relevance of maladaptive intra-cardiac vortex dynamics in the geometrical adaptation of the dysfunctional heart. We employed an in vivo model of patients who present a stable normal heart function in virtue of the cardiac resynchronization therapy (CRT, bi-ventricular pace-maker) and who are expected to develop left ventricle remodeling if pace-maker was switched off. Intra-ventricular fluid dynamics is analyzed by echocardiography (Echo-PIV). Under normal conditions, the flow presents a longitudinal alignment of the intraventricular hemodynamic forces. When pacing is temporarily switched off, flow forces develop a misalignment hammering onto lateral walls, despite no other electro-mechanical change is noticed. Hemodynamic forces result to be the first event that evokes a physiological activity anticipating cardiac changes and could help in the prediction of longer term heart adaptations. PMID:25529139

Pedrizzetti, Gianni; Martiniello, Alfonso R; Bianchi, Valter; D'Onofrio, Antonio; Caso, Pio; Tonti, Giovanni

2015-01-21

164

Pulmonary and Cardiac Function in Asymptomatic Obese Subjects and Changes following a Structured Weight Reduction Program: A Prospective Observational Study  

PubMed Central

Background The prevalence of obesity is rising. Obesity can lead to cardiovascular and ventilatory complications through multiple mechanisms. Cardiac and pulmonary function in asymptomatic subjects and the effect of structured dietary programs on cardiac and pulmonary function is unclear. Objective To determine lung and cardiac function in asymptomatic obese adults and to evaluate whether weight loss positively affects functional parameters. Methods We prospectively evaluated bodyplethysmographic and echocardiographic data in asymptomatic subjects undergoing a structured one-year weight reduction program. Results 74 subjects (32 male, 42 female; mean age 42±12 years) with an average BMI 42.5±7.9, body weight 123.7±24.9 kg were enrolled. Body weight correlated negatively with vital capacity (R?=??0.42, p<0.001), FEV1 (R?=??0.497, p<0.001) and positively with P 0.1 (R?=?0.32, p?=?0.02) and myocardial mass (R?=?0.419, p?=?0.002). After 4 months the study subjects had significantly reduced their body weight (?26.0±11.8 kg) and BMI (?8.9±3.8) associated with a significant improvement of lung function (absolute changes: vital capacity +5.5±7.5% pred., p<0.001; FEV1+9.8±8.3% pred., p<0.001, ITGV+16.4±16.0% pred., p<0.001, SR tot ?17.4±41.5% pred., p<0.01). Moreover, P0.1/Pimax decreased to 47.7% (p<0.01) indicating a decreased respiratory load. The change of FEV1 correlated significantly with the change of body weight (R?=??0.31, p?=?0.03). Echocardiography demonstrated reduced myocardial wall thickness (?0.08±0.2 cm, p?=?0.02) and improved left ventricular myocardial performance index (?0.16±0.35, p?=?0.02). Mitral annular plane systolic excursion (+0.14, p?=?0.03) and pulmonary outflow acceleration time (AT +26.65±41.3 ms, p?=?0.001) increased. Conclusion Even in asymptomatic individuals obesity is associated with abnormalities in pulmonary and cardiac function and increased myocardial mass. All the abnormalities can be reversed by a weight reduction program. PMID:25233078

Held, Matthias; Mittnacht, Maria; Kolb, Martin; Karl, Sabine; Jany, Berthold

2014-01-01

165

Cardiac Rehabilitation After Acute Myocardial Infarction Resuscitated From Cardiac Arrest  

PubMed Central

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

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

2014-01-01

166

Preference heterogeneity and choice of cardiac rehabilitation program: results from a discrete choice experiment.  

PubMed

This paper focuses on the elicitation of patients' preferences for cardiac rehabilitation activities from a discrete choice experiment using a mixed model. We observed a high level of preference heterogeneity among patients for all the five cardiac rehabilitation activities--even when age and smoking status were taken into account. The random parameter model provided additional policy relevant information as well as a better fit to the data than did the standard logit model. The paper focuses on one of the potential problems with the standard logit specification which in the worst case can lead to wrong policy conclusions by assuming homogeneity in preferences across individuals. The generalised RPL specification may be a more appropriate specification that can provide additional information on the heterogeneity preferences. PMID:17728004

Kjaer, Trine; Gyrd-Hansen, Dorte

2008-01-01

167

Incidence of new onset atrial fibrillation in patients with permanent pacemakers and the relation to the pacing mode  

PubMed Central

Background Atrial fibrillation is a relatively common arrhythmia often seen in patients with permanent pacemakers. In this study we aimed to assess the incidence of atrial fibrillation in patients whose pacemakers were programmed to pace in the right ventricle (VVI) and compared it with patients whose pacemakers were programmed in non-VVI mode(i.e. AAI or DDD). Material/Methods Records of the patients with permanent pacemaker or implantable-cardioverter-defibrillator were evaluated and analyzed. These patients had regular periodic follow-up evaluation over the last 10 years. (January 1, 2002 to December 31, 2012). Patient demographic, pacemaker data, pacing mode, review and analysis of arrhythmia log for occurrence of new atrial fibrillation and echocardiographic findings for left atrial size, mitral regurgitation, were analyzed and recorded. Left atrial size was classified as mild, moderate or severe enlargement, depending on the left atrial dimension. Results Average age was 68 years. There was no gender predominance (51% male). Mean follow-up duration was 6 years and 3 months. Hispanic population represented the majority of the patients (65.4%). Majority of the devices (80.0%) were programmed as DDD pacing mode. Fifty-five patients (52.8%) did not develop atrial fibrillation. 85.7% of the patients paced in VVI-mode had atrial fibrillation while atrial fibrillation occurred in 37.4% among patients paced in non-VVI-mode. This difference was statistically significant (P<0.0001). Conclusions Right ventricular pacing in a VVI mode was associated with higher incidence of atrial fibrillation, mitral regurgitation and left atrial enlargement. Non-VVI based pacing demonstrated lower incidence of new onset atrial fibrillation. PMID:24535068

Said, Sarmad; Alkhateeb, Haider; Cooper, Chad J.; Gosavi, Sucheta; Dwivedi, Alok; Paez, David; Abedin, Zainul

2014-01-01

168

Membranes as possible pacemakers of metabolism.  

PubMed

Basal metabolic rate (BMR) varies dramatically among vertebrate species, both (i) being several fold higher in the endothermic mammals and birds compared to the ectothermic reptiles, amphibians and fish, and (ii) being much greater, on a body mass basis, in small vertebrates compared to large vertebrates. These differences in whole animal BMR are also manifest at the cellular level with substantial contributions to basal metabolic activity from the maintenance of various trans-membrane gradients. The percentage contribution of various processes to basal metabolism is remarkably consistent between different vertebrates and when BMR varies, the components of metabolic activity vary in relative unison. Membrane composition also varies between vertebrates and the degree of polyunsaturation of membrane phospholipids is correlated with cellular metabolic activity. In general, the tissue phospholipids and thus membrane bilayers of endotherms are more polyunsaturated than those from similar-sized ectotherms. In mammals membrane polyunsaturation is allometrically related to body mass. We suggest that membranes can act as pacemakers for overall metabolic activity. We propose that such membrane polyunsaturation increases the molecular activity of many membrane-bound proteins and consequently some specific membrane leak-pump cycles and cellular metabolic activity. We hypothesize a possible mechanistic basis for this effect that is based on a greater transfer of energy during intermolecular collisions of membrane proteins with the unsaturated two carbon units (C=C) of polyunsaturates compared to the single carbon units of saturated acyl chains, as well as the more even distribution of such units throughout the depth of the bilayer when membranes contain polyunsaturated acyl chains compared to monounsaturated ones. The proposed pacemaker role of differences in membrane bilayer composition is briefly discussed with respect to the brain (and sensory cells), evolution of mammalian endothermic metabolism, and its clinical implications for humans. PMID:10433891

Hulbert, A J; Else, P L

1999-08-01

169

Pacemaker activity and ionic currents in mouse atrioventricular node cells  

PubMed Central

It is well established that pacemaker activity of the sino-atrial node (SAN) initiates the heartbeat. However, the atrioventricular node (AVN) can generate viable pacemaker activity in case of SAN failure, but we have limited knowledge of the ionic bases of AVN automaticity. We characterized pacemaker activity and ionic currents in automatic myocytes of the mouse AVN. Pacemaking of AVN cells (AVNCs) was lower than that of SAN pacemaker cells (SANCs), both in control conditions and upon perfusion of isoproterenol (ISO). Block of INa by tetrodotoxin (TTX) or of ICa,L by isradipine abolished AVNCs pacemaker activity. TTX-resistant (INar) and TTX-sensitive (INas) Na+ currents were recorded in mouse AVNCs, as well as T-(ICa,T) and L-type (ICa,L) Ca2+ currents. ICa,L density was lower than in SANCs (51%). The density of the hyperpolarization-activated current, (If) and that of the fast component of the delayed rectifier current (IKr) were, respectively, lower (52%) and higher (53%) in AVNCs than in SANCs. Pharmacological inhibition of If by 3 µM ZD-7228 reduced pacemaker activity by 16%, suggesting a relevant role for If in AVNCs automaticity. Some AVNCs expressed also moderate densities of the transient outward K+ current (Ito). In contrast, no detectable slow component of the delayed rectifier current (IKs) could be recorded in AVNCs. The lower densities of If and ICa,L, as well as higher expression of IKr in AVNCs than in SANCs may contribute to the intrinsically slower AVNCs pacemaking than that of SANCs. PMID:21406959

Marger, Laurine; Mesirca, Pietro; Alig, Jacqueline; Torrente, Angelo; Dubel, Stefan; Engeland, Birgit; Kanani, Sandra; Fontanaud, Pierre; Striessnig, Jörg; Shin, Hee-Sup; Isbrandt, Dirk; Ehmke, Heimo; Nargeot, Joël

2011-01-01

170

Automatic Segmentation of the Left Ventricle in Cardiac MRI Using Local Binary Fitting Model and Dynamic Programming Techniques  

PubMed Central

Segmentation of the left ventricle is very important to quantitatively analyze global and regional cardiac function from magnetic resonance. The aim of this study is to develop a novel algorithm for segmenting left ventricle on short-axis cardiac magnetic resonance images (MRI) to improve the performance of computer-aided diagnosis (CAD) systems. In this research, an automatic segmentation method for left ventricle is proposed on the basis of local binary fitting (LBF) model and dynamic programming techniques. The validation experiments are performed on a pool of data sets of 45 cases. For both endo- and epi-cardial contours of our results, percentage of good contours is about 93.5%, the average perpendicular distance are about 2 mm. The overlapping dice metric is about 0.91. The regression and determination coefficient between the experts and our proposed method on the LV mass is 1.038 and 0.9033, respectively; they are 1.076 and 0.9386 for ejection fraction (EF). The proposed segmentation method shows the better performance and has great potential in improving the accuracy of computer-aided diagnosis systems in cardiovascular diseases. PMID:25500580

Hu, Huaifei; Gao, Zhiyong; Liu, Liman; Liu, Haihua; Gao, Junfeng; Xu, Shengzhou; Li, Wei; Huang, Lu

2014-01-01

171

Evaluating the Interactive Web-Based Program, Activate Your Heart, for Cardiac Rehabilitation Patients: A Pilot Study  

PubMed Central

Background Conventional cardiac rehabilitation (CR) programs are traditionally based on time-constrained, structured, group-based programs, usually set in hospitals or leisure centers. Uptake for CR remains poor, despite the ongoing evidence demonstrating its benefits. Additional alternative forms of CR are needed. An Internet-based approach may offer an alternative mode of delivering CR that may improve overall uptake. Activate Your Heart (AYH) is a Web-based CR program that has been designed to support individuals with coronary heart disease (CHD). Objective The aim of this pilot study was to observe the outcome for participants following the AYH program. Methods We conducted a prospective observational trial, recruiting low-risk patients with CHD. Measures of exercise, exercise capacity, using the Incremental Shuttle Walk Test (ISWT), dietary habits, and psychosocial well-being were conducted by a CR specialist at baseline and at 8 weeks following the Web-based intervention. Results We recruited 41 participants; 33 completed the program. We documented significant improvements in the ISWT distance (mean change 49.69 meters, SD 68.8, P<.001), and Quality of Life (QOL) (mean change 0.28, SD 0.4, P<.001). Dietary habits improved with an increased proportion of patients consuming at least 5 portions of fruit and vegetables per day, (22 [71%] to 29 [94%] P=.01) and an increased proportion of patients consuming at least 2 portions of oily fish per week (14 [45%] to 21 [68%], P=.01). We did not detect changes in anxiety and depression scores or exercise behavior. Conclusions We observed important improvements in exercise capacity, QOL, and dietary habits in a group of participants following a Web-based CR program. The program may offer an alternative approach to CR. A mobile version has been developed and we need to conduct further trials to establish its value compared to supervised CR. PMID:25359204

Boyce, Sally; Houchen-Wolloff, Linzy; Sewell, Louise; Singh, Sally

2014-01-01

172

Arrhythmia resulting from sensing malfunction in a P wave triggered pacemaker.  

PubMed

P wave triggered pacemakers can produce complicated arrhythmias during normal function. A ventricular, R wave inhibited pacemaker and an atrial sensing pacemaker were both present and functioning normally in the patient reported here. A premature paced beat was observed every 12th beat which resulted from discharge of the atrial sensing pacemaker. This arrhythmia appeared because a "P" wave occurred during the noise sampling period of the atrial sensing pacemaker, disabling the demand function and resulting in generator discharge on or near the T wave of a preceding unsensed beat while the pacemaker was in the asynchronous mode. PMID:7430871

Curtis, G P; Lief, L H

1980-10-01

173

A 9-year-old boy with severe diphtherial infection and cardiac complications.  

PubMed

The incidence of diphtheria has decreased since the introduction of an effective vaccine. However, in countries with low vaccination rates it has now become a re-emerging disease. Complications from diphtheria commonly include upper airway obstruction and cardiac complications. We present a 9-year-old boy who was diagnosed with diphtheria. He presented with fever, tonsilar plaques, respiratory failure and an incomplete vaccination history. He was endotracheal intubated and received diphtheria antitoxin and penicillin on the first day of hospitalisation. He developed progressive arrhythmias and fulminant myocarditis despite early identification and treatment with equine antitoxin and antibiotics. After a temporary transvenous pacemaker insertion due to third-degree atrioventricular block and hypotension for 1?week, he developed myocardial perforation from the pacemaker tip resulting in pericardial effusion. The treatment included emergency pericardiocentesis and pacemaker removal. His electrocardiogram showed a junctional rhythm with occasional premature ventricular complexes. He then developed ventricular tachycardia and cardiac arrest and finally died. PMID:25414216

Washington, Charles Henry; Issaranggoon Na Ayuthaya, Satja; Makonkawkeyoon, Krit; Oberdorfer, Peninnah

2014-01-01

174

The Effects of a Cardiac Rehabilitation Program Tailored for Women on Global Quality of Life: A Randomized Clinical Trial  

PubMed Central

Abstract Background Women with heart disease have adverse psychosocial profiles and poor attendance in cardiac rehabilitation (CR) programs. Few studies examine CR programs tailored for women for improving their quality of life (QOL). Methods This randomized clinical trial (RCT) compared QOL among women in a traditional CR program with that of women completing a tailored program that included motivational interviewing guided by the Transtheoretical Model (TTM) of behavior change. Two measures of QOL, the Multiple Discrepancies Theory questionnaire (MDT) and the Self-Anchoring Striving Scale (SASS), were administered to 225 women at baseline, postintervention, and 6-month follow-up. Analysis of Variance (ANOVA) was used to compare changes in QOL scores over time. Results Baseline MDT and SASS scores were 35.1 and 35.5 and 7.1 and 7.0 for the tailored and traditional CR groups, respectively. Postintervention, MDT and SASS scores increased to 37.9 and 7.9, respectively, for the tailored group compared with 35.9 and 7.1 for the traditional group. Follow-up scores were 37.7 and 7.6 for the tailored group and 35.7 and 7.1 for the traditional group. Significant group by time interactions were found. Subsequent tests revealed that MDT and SASS scores for the traditional group did not differ over time. The tailored group showed significantly increased MDT and SASS scores from baseline to posttest, and despite slight attenuation from posttest to 6-month follow-up, MDT and SASS scores remained higher than baseline. Conclusions The CR program tailored for women significantly improved global QOL compared with traditional CR. Future studies should explore the mechanisms by which such programs affect QOL. PMID:20846018

Beckstead, Jason W.

2010-01-01

175

A pedometer-based physical activity intervention for patients entering a maintenance cardiac rehabilitation program: a pilot study  

PubMed Central

Purpose To compare the effects of an individualized pedometer-driven physical activity (PA) intervention with the usual time-based PA recommendations given to patients entering a maintenance cardiac rehabilitation (CR) program. Methods A total of 18 subjects entering a maintenance CR program were recruited and completed the study. Subjects were randomized into pedometer feedback [PF: n=10 (2 women), 53.3±8.1 yrs] and usual care [UC: n=8 (2 women), 59.4±9.9 yrs] groups. New Lifestyles NL-1000 pedometers were used to monitor ambulatory PA. Subjects in both groups participated in the same maintenance CR program for a total of 8 weeks and all were encouraged to obtain a minimum of 30-40 min/d of moderate-vigorous-intensity physical activity (MVPA), on days they did not attend CR. Subjects in the PF group were given individualized daily stepcount goals (increase 10% of baseline steps/d each week) for weeks 2-8. Ambulatory PA was measured with pedometers, recording both total number of steps/d and min/d of MVPA. Measures were obtained during the first week of the maintenance CR program and during the 8th week. Data were also compared between days subjects attended and on days they did not attend. Results By the 8th week of CR, PF subjects increased daily stepcounts by 42% (2,297±1,606 steps/d, P=0.001), with a 36% increase on CR days (2,654±2,089 steps/d, P=0.003) and a 45% increase on days they did not attend CR (1,872±2,026 steps/d, P=0.017). There were no changes observed in the UC group. Conclusions Providing pedometers with individualized stepcount goals to patients entering a CR program was superior to the usual time-based PA recommendations for increasing PA. PMID:24282749

Jones, Jason; Riggin, Katrina; Strath, Scott J.

2013-01-01

176

An Extremely Rare Reason for Failure of Left Sided Pacemaker Implantation  

PubMed Central

We reported a case of isolated anomaly of the left brachiocephalic vein which is diagnosed during a permanent pacemaker implantation. It is a very rare anomaly and makes the left sided pacemaker implantation impossible. PMID:25505996

Öztürk, Ali; Özcan, Emin Evren; Genç, Berhan

2014-01-01

177

An extremely rare reason for failure of left sided pacemaker implantation.  

PubMed

We reported a case of isolated anomaly of the left brachiocephalic vein which is diagnosed during a permanent pacemaker implantation. It is a very rare anomaly and makes the left sided pacemaker implantation impossible. PMID:25505996

Ozel, Erdem; Oztürk, Ali; Ozcan, Emin Evren; Genç, Berhan

2014-01-01

178

Technology utilization program report  

NASA Technical Reports Server (NTRS)

The application of aerospace technology to the solution of public health and industrial problems is reported. Data cover: (1) development of an externally rechargeable cardiac pacemaker, (2) utilization of ferrofluids-colloidal suspensions of ferrite particles - in the efficient separation of nonferrous metals as Ni, Zn, Cu, and Al from shredded automobile scrap, and (3) development of a breathing system for fire fighters.

1974-01-01

179

Electromagnetic interference of implantable cardiac devices from a shoulder massage machine.  

PubMed

Shoulder massage machines have two pads that are driven by solenoid coils to perform a per cussive massage on the shoulders. There have been concerns that such machines might create electromagnetic interference (EMI) in implantable cardiac devices because of the time-varying magnetic fields produced by the alternating current in the solenoid coils. The objective of this study was to investigate the potential EMI from one such shoulder massage machine on implantable cardiac devices. We measured the distribution profile of the magnetic field intensity around the massage machine. Furthermore, we performed an inhibition test and an asynchronous test on an implantable cardiac pacemaker using the standardized Irnich human body model. We examined the events on an implantable cardioverter-defibrillator (ICD) using a pacemaker programmer while the massage machine was in operation. The magnetic field distribution profile exhibited a peak intensity of 212 (A/m) in one of the solenoid coils. The maximal interference distance between the massage machine and the implantable cardiac pacemaker was 28 cm. Ventricular fibrillation was induced when the massage machine was brought near the electrode of the ICD and touched the Irnich human body model. It is necessary to provide a "don't use" warning on the box or the exterior of the massage machines or in the user manuals and to caution patients with implanted pacemakers about the dangers and appropriate usage of massage machines. PMID:24710851

Yoshida, Saeko; Fujiwara, Kousaku; Kohira, Satoshi; Hirose, Minoru

2014-09-01

180

Cardiac-Resynchronization Therapy with or without an Implantable Defibrillator in Advanced Chronic Heart Failure  

Microsoft Academic Search

background We tested the hypothesis that prophylactic cardiac-resynchronization therapy in the form of biventricular stimulation with a pacemaker with or without a defibrillator would reduce the risk of death and hospitalization among patients with advanced chronic heart failure and intraventricular conduction delays. methods A total of 1520 patients who had advanced heart failure (New York Heart Association class III or

Michael R. Bristow; Leslie A. Saxon; John Boehmer; Steven Krueger; David A. Kass; Teresa De Marco; Peter Carson; Lorenzo DiCarlo; David DeMets; Bill G. White; Dale W. DeVries; Arthur M. Feldman

2010-01-01

181

The neurochemical basis of photic entrainment of the circadian pacemaker  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

182

Entrainment of coupled oscillators on regular networks by pacemakers.  

PubMed

We study Kuramoto oscillators, driven by one pacemaker, on d-dimensional regular topologies with nearest neighbor interactions. We derive the analytical expressions for the common frequency in the case of phase-locked motion and for the critical frequency of the pacemaker, placed at an arbitrary position in the lattice, so that above the critical frequency no phase-locked motion is possible. We show that the mere change in topology from an open chain to a ring induces synchronization for a certain range of pacemaker frequencies and couplings, while keeping the other parameters fixed. Moreover, we demonstrate numerically that the critical frequency of the pacemaker decreases as a power of the linear size of the lattice with an exponent equal to the dimension of the system. This leads in particular to the conclusion that for infinite-dimensional topologies the critical frequency for having entrainment decreases exponentially with increasing size of the system, or, more generally, with increasing depth of the network, that is, the average distance of the oscillators from the pacemaker. PMID:16605642

Radicchi, Filippo; Meyer-Ortmanns, Hildegard

2006-03-01

183

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

PubMed Central

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

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

2010-01-01

184

Surgical removal of a giant vegetation on permanent endocavitary pacemaker wire and lead.  

PubMed

Pacemaker lead infections are rare. There are only about 0.4%-1.1% of the patients who have been implanted permanent pacemakers suffering from serious infections which lead to endocarditis. Generally, removal of the infected pacemaker wire and lead, long-term anti-infection therapy, and implantation of a new pacemaker to another anatomic site are accepted approaches for these patients. PMID:22218056

Guo-tao, Ma; Qi, Miao; Chao-ji, Zhang; Li-hua, Cao

2011-12-01

185

Are Electronic Cardiac Devices Still Evolving?  

PubMed Central

Summary Objectives The goal of this paper is to review some important issues occurring during the past year in Implantable devices. Methods First cardiac implantable device was proposed to maintain an adequate heart rate, either because the heart’s natural pacemaker is not fast enough, or there is a block in the heart’s electrical conduction system. During the last forty years, pacemakers have evolved considerably and become programmable and allow to configure specific patient optimum pacing modes. Various technological aspects (electrodes, connectors, algorithms diagnosis, therapies, …) have been progressed and cardiac implants address several clinical applications: management of arrhythmias, cardioversion / defibrillation and cardiac resynchronization therapy. Results Observed progress was the miniaturization of device, increased longevity, coupled with efficient pacing functions, multisite pacing modes, leadless pacing and also a better recognition of supraventricular or ventricular tachycardia’s in order to deliver appropriate therapy. Subcutaneous implant, new modes of stimulation (leadless implant or ultrasound lead), quadripolar lead and new sensor or new algorithm for the hemodynamic management are introduced and briefly described. Each times, the main result occurring during the two past years are underlined and repositioned from the history, remaining limitations are also addressed. Conclusion Some important technological improvements were described. Nevertheless, news trends for the future are also considered in a specific session such as the remote follow-up of the patient or the treatment of heart failure by neuromodulation. PMID:25123732

Mabo, P.

2014-01-01

186

A rare cause of pacemaker failure: interatrial block.  

PubMed

Pacemaker and implantable cardioverter defibrillators (ICD) systems are useful in detection and differentiation of many symptomatic and asymptomatic arrhythmias. In this report, we described a rare condition that caused by failure in detection of a clinical tachyarrhythmia by a dual chamber pacemaker that implanted because of intermittent atrioventricular (AV) block and sinus node disease in a 46-year-old patient. In our case, bidirectional interatrial block was demonstrated; and the symptoms associated with high ventricular rate caused by left atrial tachyarrhythmias relieved after AV node ablation. PMID:24047493

Demircan, Sabri; Yuksel, Serkan; Gulel, Okan

2013-09-01

187

A Chance-Constraint Programming Approach To Preoperatve Planning of Robotic Cardiac Surgery Under Task-Level Uncertainty.  

PubMed

In this paper, a novel formulation for robust surgical planning of robotics-assisted minimally invasive cardiac surgery based on patient-specific preoperative images is proposed. In this context, robustness is quantified in terms of the likelihood of intraoperative collisions and of joint limit violations. The proposed approach provides a more accurate and complete formulation than existing deterministic approaches in addressing uncertainty at the task level. Moreover, it is demonstrated that the dexterity of robotic arms can be quantified as a cross-entropy term. The resulting planning problem is rendered as a chanceconstrained entropy maximization problem seeking a plan with the least susceptibility towards uncertainty at the task level, while maximizing the dexterity (cross-entropy term). By such treatment of uncertainty at the task level, spatial uncertainty pertaining to mismatches between the patient-specific anatomical model and that of the actual intraoperative situation is also indirectly addressed. As a solution method, the Unscented Transform is adopted to efficiently transform the resulting chance-constrained entropy maximization problem into a constrained nonlinear program without resorting to computationally expensive particlebased methods.In this paper, a novel formulation for robust surgical planning of robotics-assisted minimally invasive cardiac surgery based on patient-specific preoperative images is proposed. In this context, robustness is quantified in terms of the likelihood of intraoperative collisions and of joint limit violations. The proposed approach provides a more accurate and complete formulation than existing deterministic approaches in addressing uncertainty at the task level. Moreover, it is demonstrated that the dexterity of robotic arms can be quantified as a cross-entropy term. The resulting planning problem is rendered as a chanceconstrained entropy maximization problem seeking a plan with the least susceptibility towards uncertainty at the task level, while maximizing the dexterity (cross-entropy term). By such treatment of uncertainty at the task level, spatial uncertainty pertaining to mismatches between the patient-specific anatomical model and that of the actual intraoperative situation is also indirectly addressed. As a solution method, the Unscented Transform is adopted to efficiently transform the resulting chance-constrained entropy maximization problem into a constrained nonlinear program without resorting to computationally expensive particlebased methods. PMID:24718580

Azimian, Hamidreza; Naish, Michael; Kiaii, Bob; Patel, Rajni

2014-04-01

188

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

ERIC Educational Resources Information Center

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…

Gutin, Bernard

189

Overdrive Ventricular Pacing in Pacemaker Recipients with Permanent Atrial Fibrillation and Sleep Apnea  

PubMed Central

Study Objectives: Cardiac pacing is ineffective in obstructive sleep apnea (SA), but it can alleviate central SA/Cheyne-Stokes respiration (CSA) in patients with heart failure (HF). We examined whether overnight overdrive ventricular pacing (OVP) has an effect on SA in pacemaker recipients with permanent atrial fibrillation (AF). Methods: An apnea-hypopnea index (AHI) ? 15 was confirmed in 28/38 patients screened by finger pulse oximetry during overnight ventricular pacing at a backup rate of 40 bpm (BUV40). These patients (23 men, 77.9 ± 7.6 y, BMI 27.6 ± 5.1 kg/m2) were randomly assigned to 2 consecutive nocturnal ventilation polygraphies with BUV40 versus OVP at 20 bpm above the mean nocturnal heart rate observed during screening. Results: During BUV40 versus OVP, (1) mean heart rate was 49 ± 8 versus 71 ± 8 bpm (p < 0.0001) and percent ventricular pacing 36% ± 38% versus 96% ± 6% (p < 0.0001); (2) AHI was 35.4 ± 11.9 versus 32.5 ± 15.5 (p = ns), central AHI 23.9 ± 11.8 versus 19.1 ± 12.7 (p < 0.001), and obstructive AHI 11.6 ± 13.1 versus 13.5 ± 15.9 (p = ns). In 15/28 patients without HF, mean left ventricular ejection fraction (LVEF) was 51% ± 17%, AHI was 37.6 ± 11.0 during BUV40 and 39.0 ± 11.5 during OVP, versus 32.8 ± 12.9 and 24.9 ± 16.5 in 13/28 patients with HF (p = 0.02) and mean LVEF 35% ± 15% (p = 0.01). Between the 2 subgroups, (1) central AHI was 23.6 ± 12.4 during BUV40 and 21.5 ± 14.0 during OVP versus 24.1 ± 11.6 and 16.2 ± 10.7 (p = 0.05); (2) obstructive AHI was 14.0 ± 13.7 during BUV40 and 17.6 ± 16.5 during OVP versus 8.8 ± 12.3 and 8.7 ± 14.3 (p = ns). Conclusions: The prevalence of SA, predominantly central, was high in our pacemaker recipients with permanent AF. In those with HF, a single overnight OVP resulted in modest improvement in central events. Citation: Bordier P; Maurice-Tison S; Ramana NK. Overdrive ventricular pacing in pacemaker recipients with permanent atrial fibrillation and sleep apnea. J Clin Sleep Med 2012;8(3):257-264. PMID:22701382

Bordier, Philippe; Maurice-Tison, Sylvie; Ramana, Nishi Krishna

2012-01-01

190

Group-mediated activity counseling and traditional exercise therapy programs: Effects on health-related quality of life among older adults in cardiac rehabilitation  

Microsoft Academic Search

Background: Regular physical activity has been consistently related to improvements in health- related quality of life (HRQL) in older\\u000a adults. Nevertheless, systematic investigations of the influence of exercise therapy on older men and women enrolled in cardiac\\u000a rehabilitation remain sparse.Purpose: The primary purpose of this investigation was to compare the effects of a group-mediated cognitive behavioral physical activity\\u000a intervention program

Brian C. Focht; Lawrence R. Brawley; W. Jack Rejeski; Walter T. Ambrosius

2004-01-01

191

Aspergillus fumigatus pacemaker lead endocarditis: A case report and review of the literature  

PubMed Central

The diagnosis of fungal endocarditis requires a high index of clinical suspicion. Rarely, pacemaker implantation may be a risk factor for the development of fungal endocarditis. A 71-year-old man with a history of multiple transvenous pacemaker manipulations and fever of an uncertain source is described. A diagnosis of culture-negative pacemaker endocarditis was established only after repeat transthoracic echocardiography. Amphotericin B was instituted; however, the patient developed a cerebral infarct and died. Postmortem examination demonstrated Aspergillus fumigatus within a large pacemaker lead thrombus, tricuspid and aortic valve vegetations, and septic pulmonary and renal emboli. The present report describes the clinical and pathological features of a rare case of Aspergillus fumigatus pacemaker lead endocarditis and suggests that serial echocardiograms may be effective in the early detection of pacemaker lead vegetations. The diagnostic features and therapeutic management of pacemaker lead endocarditis are reviewed. PMID:16568159

Leong, Roger; Gannon, Brian R; Childs, Tim J; Isotalo, Phillip A; Abdollah, Hoshiar

2006-01-01

192

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

PubMed

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

Speiser, Bernadette; Dutra-Brice, Cynthia

2014-01-01

193

Differentially timed extracellular signals synchronize pacemaker neuron clocks.  

PubMed

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

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

194

Evaluation of a self-management patient education program for patients with chronic heart failure undergoing inpatient cardiac rehabilitation: study protocol of a cluster randomized controlled trial  

PubMed Central

Background Chronic heart failure requires a complex treatment regimen on a life-long basis. Therefore, self-care/self-management is an essential part of successful treatment and comprehensive patient education is warranted. However, specific information on program features and educational strategies enhancing treatment success is lacking. This trial aims to evaluate a patient-oriented and theory-based self-management educational group program as compared to usual care education during inpatient cardiac rehabilitation in Germany. Methods/Design The study is a multicenter cluster randomized controlled trial in four cardiac rehabilitation clinics. Clusters are patient education groups that comprise HF patients recruited within 2 weeks after commencement of inpatient cardiac rehabilitation. Cluster randomization was chosen for pragmatic reasons, i.e. to ensure a sufficient number of eligible patients to build large-enough educational groups and to prevent contamination by interaction of patients from different treatment allocations during rehabilitation. Rehabilitants with chronic systolic heart failure (n?=?540) will be consecutively recruited for the study at the beginning of inpatient rehabilitation. Data will be assessed at admission, at discharge and after 6 and 12 months using patient questionnaires. In the intervention condition, patients receive the new patient-oriented self-management educational program, whereas in the control condition, patients receive a short lecture-based educational program (usual care). The primary outcome is patients’ self-reported self-management competence. Secondary outcomes include behavioral determinants and self-management health behavior (symptom monitoring, physical activity, medication adherence), health-related quality of life, and treatment satisfaction. Treatment effects will be evaluated separately for each follow-up time point using multilevel regression analysis, and adjusting for baseline values. Discussion This study evaluates the effectiveness of a comprehensive self-management educational program by a cluster randomized trial within inpatient cardiac rehabilitation in Germany. Furthermore, subgroup-related treatment effects will be explored. Study results will contribute to a better understanding of both the effectiveness and mechanisms of a self-management group program as part of cardiac rehabilitation. Trial registration German Clinical Trials Register: DRKS00004841; WHO International Clinical Trials: = DRKS00004841 PMID:23968340

2013-01-01

195

Induction of diverse cardiac cell types by reprogramming fibroblasts with cardiac transcription factors.  

PubMed

Various combinations of cardiogenic transcription factors, including Gata4 (G), Hand2 (H), Mef2c (M) and Tbx5 (T), can reprogram fibroblasts into induced cardiac-like myocytes (iCLMs) in vitro and in vivo. Given that optimal cardiac function relies on distinct yet functionally interconnected atrial, ventricular and pacemaker (PM) cardiomyocytes (CMs), it remains to be seen which subtypes are generated by direct reprogramming and whether this process can be harnessed to produce a specific CM of interest. Here, we employ a PM-specific Hcn4-GFP reporter mouse and a spectrum of CM subtype-specific markers to investigate the range of cellular phenotypes generated by reprogramming of primary fibroblasts. Unexpectedly, we find that a combination of four transcription factors (4F) optimized for Hcn4-GFP expression does not generate beating PM cells due to inadequate sarcomeric protein expression and organization. However, applying strict single-cell criteria to GHMT-reprogrammed cells, we observe induction of diverse cellular phenotypes, including those resembling immature forms of all three major cardiac subtypes (i.e. atrial, ventricular and pacemaker). In addition, we demonstrate that cells induced by GHMT are directly reprogrammed and do not arise from an Nxk2.5(+) progenitor cell intermediate. Taken together, our results suggest a remarkable degree of plasticity inherent to GHMT reprogramming and provide a starting point for optimization of CM subtype-specific reprogramming protocols. PMID:25344074

Nam, Young-Jae; Lubczyk, Christina; Bhakta, Minoti; Zang, Tong; Fernandez-Perez, Antonio; McAnally, John; Bassel-Duby, Rhonda; Olson, Eric N; Munshi, Nikhil V

2014-11-01

196

Individual-, Family-, Community-, and Policy-Level Impact of a School-Based Cardiovascular Risk Detection Screening Program for Children in Underserved, Rural Areas: The CARDIAC Project  

PubMed Central

The Coronary Artery Risk Detection In Appalachian Communities (CARDIAC) Project has screened more than 80,000 children (10–12 years) for cardiovascular and diabetes risk factors over the past 15 years. Simultaneous referral and intervention efforts have also contributed to the overall program impact. In this study, we examined evidence of programmatic impact in the past decade at the individual, family, community, and policy levels from child screening outcomes, referral rates, participation in subsequent services, and policies that embed the activities of the project as a significant element. Within this period of time, fifth-grade overweight and obesity rates were maintained at a time when rates elsewhere increased. 107 children were referred for additional screening and treatment for probable familial hypercholesterolemia (FH); 82 family members were subsequently screened in family-based screening efforts. 58 grants were distributed throughout the state for community-appropriate obesity intervention. A state wellness policy embedded CARDIAC as the method of assessment and national child cholesterol screening guidelines were impacted by CARDIAC findings. The sustainability and successful impact of this school-based program within a largely underserved, rural Appalachian state are also discussed. PMID:23840946

Cottrell, Lesley; Murphy, Emily; Lilly, Christa L.; Ritchie, Susan K.; Minor, Valerie; Neal, William A.

2013-01-01

197

Long-term comparison of unipolar and bipolar pacing and sensing, using a new multiprogrammable pacemaker system.  

PubMed

Over a six-month period a comparison was made between uni- and bipolar myocardial stimulation thresholds and R-wave sensitivity in 15 consecutive pacemaker patients. The patients received a new multiprogrammable Cordis 336 A pulse generator, that could be programmed with either uni- or bipolar circuitry. In addition, rate, output, sensitivity and pacing mode could be noninvasively programmed. The occurrence of myopotential interference at different sensitivity levels was also studied. Cordis 325-161 bipolar endocardial leads were used in all patients. In one patient, the current output sometimes had to be programmed higher bipolarly than unipolarly to capture the ventricles, otherwise no differences in threshold were found. Acutely. R-wave sensitivity was superior in 9 patients (60%) in the bipolar mode. Unipolar and bipolar electrograms were equal in 4 (26.7%), whereas unipolar R-wave sensitivity was best in only 2 (13.3%) of the patients. At a six-month follow-up, the same tendency was found. In 5 patients, bipolar sensing was superior to unipolar, while anti- and bipolar sensitivity was equal in the remaining patients. Myopotential inhibition was never seen in the bipolar mode at highest sensitivity (0.8 mV) even during provocative tests (n = 15) or 24-hour Holter monitoring (n = 12). In the unipolar mode, 14/15 patients (93.3%) showed inhibition during provocative tests and 12/12 patients (100%) during monitoring at a programmed sensitivity of 0.8 mV. No patients had myopotential interference at a sensitivity level of 3.5 mV. All patients have their pacemakers programmed in the bipolar mode after six months. This study confirms earlier acute data that the bipolar pacing mode is superior to the unipolar mode for permanent pacemaker therapy. PMID:6191297

Breivik, K; Ohm, O J; Engedal, H

1983-05-01

198

Stimulating Cardiac Muscle by Light: Cardiac Optogenetics by Cell Delivery  

PubMed Central

Background After the recent cloning of light-sensitive ion channels and their expression in mammalian cells, a new field, optogenetics, emerged in neuroscience, allowing for precise perturbations of neural circuits by light. However, functionality of optogenetic tools has not been fully explored outside neuroscience; and a non-viral, non-embryogenesis based strategy for optogenetics has not been shown before. Methods and Results We demonstrate the utility of optogenetics to cardiac muscle by a tandem cell unit (TCU) strategy, where non-excitable cells carry exogenous light-sensitive ion channels, and when electrically coupled to cardiomyocytes, produce optically-excitable heart tissue. A stable channelrhodopsin2 (ChR2) expressing cell line was developed, characterized and used as a cell delivery system. The TCU strategy was validated in vitro in cell pairs with adult canine myocytes (for a wide range of coupling strengths) and in cardiac syncytium with neonatal rat cardiomyocytes. For the first time, we combined optical excitation and optical imaging to capture light-triggered muscle contractions and high-resolution propagation maps of light-triggered electrical waves, found to be quantitatively indistinguishable from electrically-triggered waves. Conclusions Our results demonstrate feasibility to control excitation and contraction in cardiac muscle by light using the TCU approach. Optical pacing in this case uses less energy, offers superior spatiotemporal control, remote access and can serve not only as an elegant tool in arrhythmia research, but may form the basis for a new generation of light-driven cardiac pacemakers and muscle actuators. The TCU strategy is extendable to (non-viral) stem cell therapy and is directly relevant to in vivo applications. PMID:21828312

Jia, Zhiheng; Valiunas, Virginijus; Lu, Zongju; Bien, Harold; Liu, Huilin; Wang, Hong-Zhang; Rosati, Barbara; Brink, Peter R.; Cohen, Ira S.; Entcheva, Emilia

2011-01-01

199

Endovascular extraction techniques for pacemaker and ICD lead extraction  

PubMed Central

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

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

2001-01-01

200

Permanent pacemaker-associated actinomycetemcomitans endocarditis: A case report  

PubMed Central

Aggregatibacter actinomycetemcomitans is a Gram-negative bacillus, member of the HACEK group of bacteria, and it is a very rare cause of endocarditis. It is also an extremely rare cause of device-associated infection of the heart. We describe the case of a 25 year-old man who presented with pacemaker-associated endocarditis due to Aggregatibacter actinomycetemcomitans and also discuss the implications and treatment of this organism. PMID:24432293

Li, Zhenhong; Madeo, Jennifer; Ahmed, Shadab; Vidal, Alex; Makaryus, Amgad; Mejia, Jose; Yasmin, Tabassum

2013-01-01

201

Serotonin Augments Gut Pacemaker Activity via 5-HT3 Receptors  

PubMed Central

Serotonin (5-hydroxytryptamine: 5-HT) affects numerous functions in the gut, such as secretion, muscle contraction, and enteric nervous activity, and therefore to clarify details of 5-HT's actions leads to good therapeutic strategies for gut functional disorders. The role of interstitial cells of Cajal (ICC), as pacemaker cells, has been recognised relatively recently. We thus investigated 5-HT actions on ICC pacemaker activity. Muscle preparations with myenteric plexus were isolated from the murine ileum. Spatio-temporal measurements of intracellular Ca2+ and electric activities in ICC were performed by employing fluorescent Ca2+ imaging and microelectrode array (MEA) systems, respectively. Dihydropyridine (DHP) Ca2+ antagonists and tetrodotoxin (TTX) were applied to suppress smooth muscle and nerve activities, respectively. 5-HT significantly enhanced spontaneous Ca2+ oscillations that are considered to underlie electric pacemaker activity in ICC. LY-278584, a 5-HT3 receptor antagonist suppressed spontaneous Ca2+ activity in ICC, while 2-methylserotonin (2-Me-5-HT), a 5-HT3 receptor agonist, restored it. GR113808, a selective antagonist for 5-HT4, and O-methyl-5-HT (O-Me-5-HT), a non-selective 5-HT receptor agonist lacking affinity for 5-HT3 receptors, had little effect on ICC Ca2+ activity. In MEA measurements of ICC electric activity, 5-HT and 2-Me-5-HT caused excitatory effects. RT-PCR and immunostaining confirmed expression of 5-HT3 receptors in ICC. The results indicate that 5-HT augments ICC pacemaker activity via 5-HT3 receptors. ICC appear to be a promising target for treatment of functional motility disorders of the gut, for example, irritable bowel syndrome. PMID:21949791

Liu, Hong-Nian; Ohya, Susumu; Nishizawa, Yuji; Sawamura, Kenta; Iino, Satoshi; Syed, Mohsin Md; Goto, Kazunori; Imaizumi, Yuji; Nakayama, Shinsuke

2011-01-01

202

Isolating Neural Correlates of the Pacemaker for Food Anticipation  

PubMed Central

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

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

2012-01-01

203

Physiological effects of light on the human circadian pacemaker  

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

204

Inter-Association Task Force Recommendations on Emergency Preparedness and Management of Sudden Cardiac Arrest in High School and College Athletic Programs: A Consensus Statement  

PubMed Central

Objective: To assist high school and college athletic programs prepare for and respond to a sudden cardiac arrest (SCA). This consensus statement summarizes our current understanding of SCA in young athletes, defines the necessary elements for emergency preparedness, and establishes uniform treatment protocols for the management of SCA. Background: Sudden cardiac arrest is the leading cause of death in young athletes. The increasing presence of and timely access to automated external defibrillators (AEDs) at sporting events provides a means of early defibrillation and the potential for effective secondary prevention of sudden cardiac death. An Inter-Association Task Force was sponsored by the National Athletic Trainers' Association to develop consensus recommendations on emergency preparedness and management of SCA in athletes. Recommendations: Comprehensive emergency planning is needed for high school and college athletic programs to ensure an efficient and structured response to SCA. Essential elements of an emergency action plan include establishment of an effective communication system, training of anticipated responders in cardiopulmonary resuscitation and AED use, access to an AED for early defibrillation, acquisition of necessary emergency equipment, coordination and integration of on-site responder and AED programs with the local emergency medical services system, and practice and review of the response plan. Prompt recognition of SCA, early activation of the emergency medical services system, the presence of a trained rescuer to initiate cardiopulmonary resuscitation, and access to early defibrillation are critical in the management of SCA. In any collapsed and unresponsive athlete, SCA should be suspected and an AED applied as soon as possible for rhythm analysis and defibrillation if indicated. PMID:17597956

Drezner, Jonathan A; Courson, Ron W; Roberts, William O; Mosesso, Vincent N; Link, Mark S; Maron, Barry J

2007-01-01

205

Successful implantation of a dual-chamber pacemaker in an ELBW infant for long QT syndrome.  

PubMed

Long QT syndromes encompass the most prevalent group of ion channelopathies. Long QT syndromes are predominantly familial and predispose the affected individual to ventricular arrhythmias and sudden death. Permanent pacemaker insertion for long QT syndrome is discouraged apart from younger patients exhibiting 2:1 atrioventricular block. However, permanent pacemaker insertion is a relatively common procedure in neonates with atrioventricular block, and dual-chamber permanent pacemaker insertion in low birth weight infants is challenging. We describe the management of long QT syndrome - type 2 - presenting in an extremely preterm neonate including epicardial, dual-chamber permanent pacemaker insertion. PMID:24905882

McCrossan, Brian; d'Udekem, Yves; Davis, Andrew Mark; Pflaumer, Andreas

2015-03-01

206

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

PubMed Central

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

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

2009-01-01

207

Connectivity of pacemaker neurons in the neonatal rat superficial dorsal horn.  

PubMed

Pacemaker neurons with an intrinsic ability to generate rhythmic burst-firing have been characterized in lamina I of the neonatal spinal cord, where they are innervated by high-threshold sensory afferents. However, little is known about the output of these pacemakers, as the neuronal populations which are targeted by pacemaker axons have yet to be identified. The present study combines patch clamp recordings in the intact neonatal rat spinal cord with tract-tracing to demonstrate that lamina I pacemaker neurons contact multiple spinal motor pathways during early life. Retrograde labeling of premotor interneurons with the trans-synaptic virus PRV-152 revealed the presence of burst-firing in PRV-infected lamina I neurons, thereby confirming that pacemakers are synaptically coupled to motor networks in the spinal ventral horn. Notably, two classes of pacemakers could be distinguished in lamina I based on cell size and the pattern of their axonal projections. While small pacemaker neurons possessed ramified axons which contacted ipsilateral motor circuits, large pacemaker neurons had unbranched axons which crossed the midline and ascended rostrally in the contralateral white matter. Recordings from identified spino-parabrachial and spino-PAG neurons indicated the presence of pacemaker activity within neonatal lamina I projection neurons. Overall, these results show that lamina I pacemakers are positioned to regulate both the level of activity in developing motor circuits as well as the ascending flow of nociceptive information to the brain, thus highlighting a potential role for pacemaker activity in the maturation of pain and sensorimotor networks in the CNS. J. Comp. Neurol., 2014. © 2014 Wiley Periodicals, Inc. PMID:25380417

Li, Jie; Kritzer, Elizabeth; Ford, Neil C; Arbabi, Shahriar; Baccei, Mark L

2014-11-01

208

Cardiac Arrest  

MedlinePLUS

... or it can stop beating. Sudden cardiac arrest (SCA) occurs when the heart develops an arrhythmia that ... is blocked. There are many possible causes of SCA. They include coronary heart disease, physical stress, and ...

209

Cardiac Paragangliomas.  

PubMed

Cardiac paraganglioma is a rare entity. We review the clinical data from 158 patients reported in 132 isolated papers, and discuss clinical presentations, imaging findings, pathology, location, therapy, and outcomes. PMID:25331372

Wang, Ji-Gang; Han, Jing; Jiang, Tao; Li, Yu-Jun

2014-10-20

210

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 ...

211

Benefits in projected pacemaker longevity and in pacing related costs conferred by automatic threshold tracking.  

PubMed

The aim of this study was to calculate the battery current drain of different VVI-VVIR pulse generators, with and without automatic adjustment of stimulation output, from the same manufacturer, and obtain projections on pacemaker longevity and pacing related costs. Twenty-five patients who had received a VVIR pacemaker (Microny SR+ 2425T) with Autocapture function, an algorithm able to provide automatic adaptation of device output coupled with continuously monitored capture threshold, were analyzed. Calculations of current drain and projections of device longevity were based on diagnostic data retrieved from device memory and on comparisons of multiple programmed settings of the same device (Microny SR+ 2425T with Autocapture, Low Output [output = 2 x Autocapture threshold, but not less than 2.4 V] versus Standard Output [5 V]). In addition, devices with Autocapture but with different battery capacities (0.35 Ah and 0.79 Ah, Microny and Regency, respectively) were compared to a standard device (battery capacity = 0.78 Ah) at 2.5-V and 5-V output settings. According to a series of assumptions, Autocapture increased device longevity by 53% (Microny) and by 245% (Regency) over a 15-year follow-up with a consequent reduction in pacing related costs of 25% (Microny) and of 57% (Regency) compared to the standard settings of a VVIR device from the same manufacturer. In conclusion, pacing with constant adaptation of generator output coupled with continuous monitoring of stimulation threshold has the potential to increase generator longevity and to reduce pacing related costs as compared to a standard device from the same manufacturer. PMID:11139923

Boriani, G; Biffi, M; Branzi, A; Mininno, A; Sigliano, R

2000-11-01

212

Pacemaker discomfort induced by the wearing of seat belts.  

PubMed

A survey was made of 100 consecutive pacemaker recipients to examine problems they may have experienced with seat belts whilst travelling by car, either as drivers (29 patients) or front seat passengers (50 patients). Twenty-one per cent of the drivers and 30% of the front seat passengers had experienced symptoms, usually of a mild nature. Re-siting of the generator was only necessary in 1 patient and no example of electrode displacement was observed. Suggestions are made as to how this problem might be overcome. PMID:4022858

Wallis, M; Todd, I; Aber, C P

1985-04-01

213

Second-, minute- and hour-metronomes of intestinal pacemakers.  

PubMed

1. Movements of the gastrointestinal tract are required for the digestion of food and the expulsion of waste products. 2. The present paper will discuss the nature of electrical rhythms underlying some intestinal motility patterns. 3. The rhythms are generated by pacemakers with cycle rates appropriate to controlling individual contractions, motor patternings or switching between different motor programmes. 4. Electrical rhythms are discussed with periods of the order of seconds, minutes and hours. 5. Particular discussion is centred on rhythms recorded from the small and large intestine of the mouse. PMID:9784929

Bywater, R A; Spencer, N J; Fida, R; Taylor, G S

1998-10-01

214

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

Microsoft Academic Search

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

D. Difrancesco; D. Noble

1985-01-01

215

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

PubMed

We used real-time imaging to detect cAMP levels in neurons of intact fly brains to study the mechanisms of circadian pacemaker synchronization by the neuropeptide pigment dispersing factor (PDF) in Drosophila. PDF receptor (PDF-R) is expressed by both M (sLNv) and E (LNd) pacemaker subclasses and is coupled to G(s?) in both cases. We previously reported that PDF-R in M pacemakers elevates cAMP levels by activating the ortholog of mammalian adenylate cyclase 3 (AC3) but that AC3 disruptions had no effect on E pacemaker sensitivity to PDF. Here, we show that PDF-R in E pacemakers activates a different AC isoform, AC78C, an ortholog of mammalian AC8. Knockdown of AC78C by transgenic RNAi substantially reduces, but does not completely abrogate, PDF responses in these E pacemakers. The knockdown effect is intact when restricted to mature stages, suggesting a physiological and not a development role for AC78C in E pacemakers. The AC78C phenotype is rescued by the overexpression of AC78C but not by overexpression of the rutabaga AC. AC78C overexpression does not disrupt PDF responses in these E pacemakers, and neither AC78C knockdown nor its overexpression disrupted locomotor rhythms. Finally, knockdown of 2 AKAPs, nervy and AKAP200, partially reduces LNd PDF responses. These findings begin to identify the components of E pacemaker PDF-R signalosomes and indicate that they are distinct from PDF-R signalosomes in M pacemakers: we propose they contain AC78C and at least 1 other AC. PMID:23929551

Duvall, Laura B; Taghert, Paul H

2013-08-01

216

Phase shifting two coupled circadian pacemakers - Implications for jet lag  

NASA Technical Reports Server (NTRS)

Two Van der Pol oscillators with reciprocal linear velocity coupling are utilized to model the response of the human circadian timing system to abrupt displacements of the environmental time cues (zeitgebers). The core temperature rhythm and sleep-wake cycle simulated by the model are examined. The relationship between the masking of circadian rhythms by environmental variables and behavioral and physiological events and the rates of resynchronization is studied. The effects of zeitgeber phase shifts and zeitgeber strength on the resynchronization rates are analyzed. The influence of intrinsic pacemakers periods and coupling strength on resynchronization are investigated. The simulated data reveal that: resynchronization after a time zone shift depends on the magnitude of the shift; the time of day of the shift has little influence on resynchronization; the strength of zeitgebers affects the rate and direction of the resynchronization; the intrinsic pacemaker periods have a significant effect on resynchronization; and increasing the coupling between the oscillators results in an increase in the rate of resynchronization. The model data are compared to transmeridian flight studies data and similar resynchronization patterns are observed.

Gander, P. H.; Kronauer, R. E.; Graeber, R. C.

1985-01-01

217

Digital Music Players Cause Interference with Interrogation Telemetry for Pacemakers and Implantable Cardioverter-Defibrillators without Affecting Device Function  

PubMed Central

Background Concern exists regarding the potential electromagnetic interaction between pacemakers, implantable cardioverter-defibrillators (ICDs) and digital music players (DMPs). A preliminary study reported interference in 50% of patients whose devices were interrogated near Apple iPods. Objective Given the high prevalence of DMP use among young patients, we sought to define the nature of interference from iPods and evaluate other DMPs. Methods Four DMPs (Apple Nano, Apple Video, SanDisk Sansa and Microsoft Zune) were evaluated against pacemakers and ICDs (PM/ICD). Along with continuous monitoring, we recorded a baseline ECG strip, sensing parameters and lead impedance at baseline and for each device. Results Among 51 patients evaluated (age 6 to 60 years, median 22), there was no interference with intrinsic device function. Interference with the programmer occurred in 41% of the patients. All four DMPs caused programmer interference, including disabled communication between the PM/ICD and programmer, noise in the ECG channel, and lost marker channel indicators. Sensing parameters and lead impedance exhibited no more than baseline variability. When the DMPs were removed six inches, there were no further programmer telemetry interactions. Conclusions Contrary to a prior report, we did not identify any evidence for electromagnetic interference between a selection of DMPs and intrinsic function of PM/ICDs. The DMPs did sometimes interfere with device-programmer communication, but not in a way that compromised device function. Therefore, we recommend that DMPs not be used during device interrogation, but suggest that there is reassuring counterevidence to mitigate the current high level of concern for interactions between DMPs and implantable cardiac rhythm devices. PMID:18362020

Webster, Gregory; Jordao, Ligia; Martuscello, Maria; Mahajan, Tarun; Alexander, Mark E.; Cecchin, Frank; Triedman, John K.; Walsh, Edward P.; Berul, Charles I.

2014-01-01

218

Comparison of Fontan Survivors with and without Pacemakers: A Report from the Pediatric Heart Network Fontan Cross Sectional Study  

PubMed Central

Objective Although many Fontan patients undergo pacemaker placement, there are few studies characterizing this population. Our purpose was to compare clinical characteristics, functional status and measures of ventricular performance in Fontan patients with and without a pacemaker. Patients and Design The NHLBI funded Pediatric Heart Network (PHN) Fontan Cross Sectional Study characterized 546 Fontan survivors. Clinical characteristics, medical history and study outcomes (Child Health Questionnaire (CHQ), echocardiographic evaluation of ventricular function, and exercise testing) were compared between subjects with and without pacemakers. Results Of 71 subjects with pacemakers (13%), 43/71 (61%) were in a paced rhythm at the time of study enrollment (age 11.9±3.4 years). Pacemaker subjects were older at study enrollment, more likely to have single left ventricles, and taking more medications. There were no differences in age at Fontan or Fontan type between the pacemaker and no pacemaker groups. There were no differences in exercise performance between groups. CHQ physical summary scores were lower in the pacemaker subjects (39.7±14.3 vs. 46.1±11.2, p = 0.001). Ventricular ejection fraction z-score was also lower (?1.4±1.9 vs. ?0.8±2.0, p = 0.05) in pacemaker subjects. Conclusions In our cohort of Fontan survivors, those with a pacemaker have poorer functional status and evidence of decreased ventricular systolic function compared to Fontan survivors without a pacemaker. PMID:22762157

Williams, Richard V.; Travison, Thomas; Kaltman, Jonathan R.; Cecchin, Frank; Colan, Steven D.; Idriss, Salim F.; Lu, Minmin; Margossian, Renee; Reed, John H.; Silver, Eric S.; Stephenson, Elizabeth A.; Vetter, Victoria L.

2012-01-01

219

Glycinergic pacemaker neurons in preBötzinger Complex of neonatal mouse  

PubMed Central

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 co-express 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: 1) ectopic bursting in rhythmic slices when depolarized during their normally silent period, and; 2) bursting when depolarized in non-rhythmic slices (following AMPA receptor blockade). 42% 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 non-trivial predictions of the functional role of excitatory and inhibitory pacemaker neurons need to be proposed and the necessary experiments performed. PMID:20219997

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

2010-01-01

220

Left Ventricular Synchrony and Function in Pediatric Patients with Definitive Pacemakers  

PubMed Central

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

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

2013-01-01

221

Frequency of cardiac arrhythmias in high- and low- yielding dairy cows  

PubMed Central

Electrocardiography (ECG) may be used to recognize cardiac disorders. Levels of milk production may change the serum electrolytes which its imbalance has a role in cardiac arrhythmia. Fifty high yielding and fifty low yielding Holstein dairy cows were used in this study. Electrocardiography was recorded by base-apex lead and blood samples were collected from jugular vein for measurement of serum elements such as sodium, potassium, calcium, phosphorous, iron and magnesium. Cardiac dysrhythmias were detected more frequent in low yielding Holstein cows (62.00%) compared to high yielding Holstein cows (46.00%). The cardiac dysrhythmias that were observed in low yielding Holstein cows included sinus arrhythmia (34.70%), wandering pacemaker (22.45 %), bradycardia (18.37%), tachycardia (10.20%), atrial premature beat (2.04%), sinoatrial block (2.04%), atrial fibrillation (8.16%) and atrial tachycardia (2.04%). The cardiac dysrhythmias were observed in high yielding Holstein cows including, sinus arrhythmia (86.95%) and wandering pacemaker (13.05%). Also, notched P wave was observed to be 30% and 14% in high- and low- yielding Holstein cows respectively. The serum calcium concentration of low yielding Holstein cows was significantly lower than that of high yielding Holstein cows. There was not any detectable significant difference in other serum elements between high- and low- yielding Holstein cows. Based on the result of present study, could be concluded that low serum concentration of calcium results to more frequent dysrhythmias in low yielding Holstein cows. PMID:25568685

Jafari Dehkordi, Afshin; Nasser Mohebi, Abdonnaser; Heidari Soreshjani, Masoumeh

2014-01-01

222

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

223

The Drosophila Circadian Pacemaker Circuit: Pas de Deux or Tarantella?  

PubMed Central

Molecular genetic analysis of the fruit fly Drosophila melanogaster has revolutionized our understanding of the transcription/translation loop mechanisms underlying the circadian molecular oscillator. More recently, Drosophila has been used to understand how different neuronal groups within the circadian pacemaker circuit interact to regulate the overall behavior of the fly in response to daily cyclic environmental cues as well as seasonal changes. Our present understanding of circadian timekeeping at the molecular and circuit level is discussed with a critical evaluation of the strengths and weaknesses of present models. Two models for circadian neural circuits are compared: one that posits that two anatomically distinct oscillators control the synchronization to the two major daily morning and evening transitions, versus a distributed network model that posits that many cell-autonomous oscillators are coordinated in a complex fashion and respond via plastic mechanisms to changes in environmental cues. PMID:18307108

Sheeba, Vasu; Kaneko, Maki; Sharma, Vijay Kumar; Holmes, Todd C.

2008-01-01

224

Does Rapid Auditory Stimulation Accelerate an Internal Pacemaker? Don't Bet on It.  

E-print Network

challenges (see, e.g., Buhusi & Meck, 2005; Grondin, 2010). In order to better understand the hypothesized, the administration of certain drugs to laboratory rats has led to behavior suggesting systematic changes in pacemaker

225

Reevaluation of Drosophila melanogaster's Neuronal Circadian Pacemakers Reveals New Neuronal Classes  

PubMed Central

In the brain of the fly Drosophila melanogaster, ?150 clock-neurons are organized to synchronize and maintain behavioral rhythms, but the physiological and neurochemical bases of their interactions are largely unknown. Here we reevaluate the cellular properties of these pacemakers by application of a novel genetic reporter and several phenotypic markers. First, we describe an enhancer trap marker called R32 that specifically reveals several previously undescribed aspects of the fly's central neuronal pacemakers. We find evidence for a previously unappreciated class of neuronal pacemakers, the lateral posterior neurons (LPNs), and establish anatomical, molecular, and developmental criteria to establish a subclass within the dorsal neuron 1 (DN1) group of pacemakers. Furthermore, we show that the neuropeptide IPNamide is specifically expressed by this DN1 subclass. These observations implicate IPNamide as a second candidate circadian transmitter in the Drosophila brain. Finally, we present molecular and anatomical evidence for unrecognized phenotypic diversity within each of four established classes of clock neurons. PMID:16856134

Shafer, Orie Thomas; Helfrich-Förster, Charlotte; Renn, Susan Christine Portia; Taghert, Paul H.

2008-01-01

226

Patients, Pacemakers, and Implantable Defibrillators: Human Values and Security for Wireless Implantable  

E-print Network

Terms Design, Human Factors, Security. INTRODUCTION Implantable medical devices (IMDs), such as pacemak Implantable Medical Devices Tamara Denning , Alan Borning , Batya Friedman , Brian T. Gill , Tadayoshi Kohno of Washington Department of Mathematics, Seattle Pacific University + Medical Device Safety Institute, Beth

Anderson, Richard

227

[Optimalization of rate adaptation using Holter functions in DDD/R pacemakers].  

PubMed

Introduction of the pacing rate adaptation according to the momentary metabolic needs added other programmable parametres which demand physician's attention during the initial postimplantation programmation and also in follow-up of pacemaker patients. The parametres setting is strictly individual with a need of feedback control. In some devices it is enabled by Holter functions as a part of pacemaker software. These methods were used to set the rate adaptive parametres in the group of 23 patients with implanted DDD/R pacemaker. The walking stress test was used. Model follow-up situations are presented in 3 case reports. Using Holter functions enables the physician to put patient's subjective complains in relation with actual heart rate--this is used to optimize the parametres of rate adaptation. The authors consider the Holter functions a necessary part of rate adaptive pacemaker software. PMID:9820057

Novotný, T; Dvorák, R; Kozák, M; Vlasínová, J

1998-06-01

228

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

PubMed Central

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

Lu, Tom Z.; Feng, Zhong-Ping

2011-01-01

229

Cardiac sarcoidosis.  

PubMed

The prognosis of sarcoidosis often considered as "benign" is significantly changed in the presence of a cardiac localization. An in-depth interview, a clinical examination together with ECG are often for most of sarcoidosis. Certain conditions (severe multisystemic sarcoidosis, rares localizations in particular neurological, renal, gastric) lead to necessary investigations: Holter ECG, echocardiography, thallium scintigraphy with dipyridamole test, PET scanner and MRI in order to identify infraclinical presentations. Diagnosis relies on guidelines of Japansese criteria, but can benefit from MRI and PET scanner even though their place is not yet clearly defined in clinical pratice. Diagnosing cardiac sarcoidosis means deciding an immunosuppressive treatment. It is highly important to gather all criteria to validate a consistent diagnosis or at least a high probability. In order to best adapt therapy, a coordinated patient care involving the cardiologist and the sarcoidosis specialist is necessary. PMID:22608949

Chapelon-Abric, Catherine

2012-06-01

230

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

NSDL National Science Digital Library

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.

Sven Kurbel (Osijek Medical Faculty Department of Physiology)

2003-09-01

231

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

PubMed Central

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

2013-01-01

232

Pacemaker lead malpositioning led to subsequent ischemic strokes despite antiplatelet and anticoagulation therapy  

PubMed Central

Pacemaker lead malpositioning may lead to severe clinical adverse events. Rarely, cases of inadvertent placement of a lead into the left ventricle are reported in the literature. We herein report a case of pacemaker lead malpositioning into the left ventricle via a persistent foramen ovale in a male caucasian patient. After this procedural adverse event, the patient suffered from two ischemic strokes despite antiplatelet and anticoagulation therapy. PMID:24650169

2014-01-01

233

Action potential and membrane currents of single pacemaker cells of the rabbit heart  

Microsoft Academic Search

Single, viable pacemaker cells were isolated from sinoatrial (S-A) and atrioventricular (A-V) nodes by treating with collagenase. In normal Tyrode solution containing 1.8 mM Ca2+, these pacemaker cells had a round configuration and contracted rhythmically at a frequency of about 150–260\\/min. The amplitude, duration, and maximum rate of rise of the spontaneous action potentials recorded using patch clamp electrodes were

Toshio Nakayama; Yoshihisa Kurachi; Akinori Noma; Hiroshi Irisawa

1984-01-01

234

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

PubMed Central

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

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

2013-01-01

235

Cardiac optogenetics  

PubMed Central

Optogenetics is an emerging technology for optical interrogation and control of biological function with high specificity and high spatiotemporal resolution. Mammalian cells and tissues can be sensitized to respond to light by a relatively simple and well-tolerated genetic modification using microbial opsins (light-gated ion channels and pumps). These can achieve fast and specific excitatory or inhibitory response, offering distinct advantages over traditional pharmacological or electrical means of perturbation. Since the first demonstrations of utility in mammalian cells (neurons) in 2005, optogenetics has spurred immense research activity and has inspired numerous applications for dissection of neural circuitry and understanding of brain function in health and disease, applications ranging from in vitro to work in behaving animals. Only recently (since 2010), the field has extended to cardiac applications with less than a dozen publications to date. In consideration of the early phase of work on cardiac optogenetics and the impact of the technique in understanding another excitable tissue, the brain, this review is largely a perspective of possibilities in the heart. It covers the basic principles of operation of light-sensitive ion channels and pumps, the available tools and ongoing efforts in optimizing them, overview of neuroscience use, as well as cardiac-specific questions of implementation and ideas for best use of this emerging technology in the heart. PMID:23457014

2013-01-01

236

The potential impact of using donations after cardiac death on the liver transplantation program and waiting list in the state of Sao Paulo, Brazil.  

PubMed

Liver transplantation was first performed at the University of Sao Paulo School of Medicine in 1968. Since then, the patient waiting list for liver transplantation has increased at a rate of 150 new cases per month. Liver transplantation itself rose 1.84-fold (from 160 to 295) from 1988 to 2004. However, the number of patients on the liver waiting list jumped 2.71-fold (from 553 to 1500). Consequently, the number of deaths on the liver waiting list moved to a higher level, from 321 to 671, increasing 2.09-fold. We have applied a mathematical model to analyze the potential impact of using a donation after cardiac death (DCD) policy on our liver transplantation program and on the waiting list. Five thousand one hundred people died because of accidents and other violent causes in our state in 2004; of these, only 295 were donors of liver grafts that were transplanted. The model assumed that 5% of these grafts would have been DCD. We found a relative reduction of 27% in the size of the liver transplantation waiting list if DCD had been used by assuming that 248 additional liver transplants would have been performed annually. In conclusion, the use of DCD in our transplantation program would reduce the pressure on our liver transplantation waiting list, reducing it by at least 27%. On the basis of this model, the projected number of averted deaths is about 41,487 in the next 20 years. PMID:19025927

Chaib, Eleazar; Massad, Eduardo

2008-12-01

237

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

PubMed

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 to device malfunctions. The frequency of malfunctions due to firmware problems will only increase as the pacemaker operations become more complex in an attempt to expand the use of the device. One reason these malfunctions arise is that there is currently no methodology for formal validation and verification of medical device software, as there are in the safety-critical domains of avionics and industrial control automation. We have developed a timed-automata based Virtual Heart Model (VHM) to act as platform for medical device software validation and verification. Through a case study involving multiple arrhythmias, this investigation shows how the VHM can be used with closed-loop operation of a pacemaker to validate the necessity and functionality of the complex mode-switch pacemaker operation. We demonstrate the correct pacemaker operation, to switch from one rhythm management mode to another, in patients with supraventricular tachycardias. (1). PMID:21096077

Jiang, Zhihao; Connolly, Allison; Mangharam, Rahul

2010-01-01

238

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

239

Transcription factor-driven conversion of quiescent cardiomyocytes to pacemaker cells  

PubMed Central

The heartbeat originates within the sinoatrial node (SAN), a small highly-specialized structure containing <10,000 genuine pacemaker cells. The ~5 billion working cardiomyocytes downstream of the SAN remain quiescent when it fails, leading to circulatory collapse and fueling a $6B/year electronic pacemaker industry. To engineer faithful biological replicas of rare SAN cells as an alternative therapeutic strategy, we expressed a gene critical for early SAN specification in working cardiomyocytes in vitro, and in vivo in a model of bradycardia. Within days of transduction with Tbx18, ventricular cardiomyocytes in culture developed spontaneous electrical firing physiologically indistinguishable from that of SAN cells, along with morphological and epigenetic features characteristic of SAN cells. Focal Tbx18 gene transfer in the guinea-pig ventricle yielded ectopic pacemaker activity in vivo, correcting a bradycardic disease phenotype. Myocytes transduced in vivo acquired the cardinal tapering morphology and physiological automaticity of native SAN pacemaker cells, while controls remained rectangular and quiescent. The creation of induced SAN-like pacemaker (iSAN) cells by Tbx18 gene transfer opens new prospects for bioengineered pacemakers. PMID:23242162

Kapoor, Nidhi; Liang, Wenbin; Marbán, Eduardo; Cho, Hee Cheol

2013-01-01

240

Marching towards regenerative cardiac therapy with human pluripotent stem cells.  

PubMed

Damage in cardiac tissues from ischemia or other pathological conditions leads to heart failure; and cell loss or dysfunction in pacemaker tissues due to congenital heart defects, aging, and acquired diseases can cause severe arrhythmias. The promise of successful therapies with stem cells to treat these conditions has remained elusive to the scientific community. However, recent advances in this field have opened new opportunities for regenerative cardiac therapy. Transplantation of cardiomyocytes derived from human pluripotent stem cells has the potential to alleviate heart disease. Since the initial derivation of human embryonic stem cells, significant progress has been made in the generation and characterization of enriched cardiomyocytes and the demonstration of the ability of these cardiomyocytes to survive, integrate, and function in animal models. The scope of therapeutic potential from pluripotent stem cell-derived cardiomyocytes has been further expanded with the invention of induced pluripotent stem cells, which can be induced to generate functional cardiomyocytes for regenerative cardiac therapy in a patient specific manner. The reprogramming technology has also inspired the recent discovery of direct conversion of fibroblasts into cardiomyocyte-like cells, which may allow endogenous cardiac repair. Regenerative cardiac therapy with human pluripotent stem cells is now moving closer to clinic testing. PMID:23819949

Maher, Kevin O; Xu, Chunhui

2013-06-01

241

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

PubMed Central

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

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

242

CARDIAC MRI SCAR PATTERNS DIFFER BY GENDER IN AN IMPLANTABLE CARDIOVERTER DEFIBRILLATOR AND CARDIAC RESYNCHRONIZATION COHORT  

PubMed Central

Background Recent meta-analyses suggest that the effectiveness of cardiac devices may differ between genders. Compared to men, women may not benefit as much from implantable defibrillators (ICDs), yet benefit more from cardiac resynchronization therapy (CRT). Myocardial scar burden is associated with increased incidence of appropriate ICD shocks but decreased response to CRT and may explain gender differences in device benefit. Objective To test the hypothesis that the extent of myocardial scar is less in women than men. Methods In 235 patients referred for primary prevention ICDs who underwent cardiac magnetic resonance imaging, we compared scar size by gender. Analyses were performed for all patients (ICD cohort) and those receiving biventricular pacemakers (CRT subgroup). Results In the ICD cohort, women (vs. men) had a higher prevalence of non-ischemic cardiomyopathy (NICM, 64% vs. 39%, p<0.001) which accounted for a smaller overall scar burden (0.5% vs 13%, p<0.01). Likewise, in the CRT subgroup, the higher prevalence of NICM in women (83% vs. 46%, p=0.01) also contributed to a smaller scar size (0 vs 13%, p<0.01). Women also had significantly less scarring of the inferolateral LV wall. Conclusions In a cohort of patients undergoing clinically indicated ICD and CRT, women had less myocardial scar than men. This difference was primarily driven by a higher prevalence of NICM in women. These findings may have important implications for the future study of gender disparities in ICD and CRT outcomes. PMID:23313802

Loring, Zak; Strauss, David G.; Gerstenblith, Gary; Tomaselli, Gordon F.; Weiss, Robert G.; Wu, Katherine C.

2013-01-01

243

Circadian clock and cardiac vulnerability: A time stamp on multi-scale neuroautonomic regulation  

NASA Astrophysics Data System (ADS)

Cardiovascular vulnerability displays a 24-hour pattern with a peak between 9AM and 11AM. This daily pattern in cardiac risk is traditionally attributed to external factors including activity levels and sleep-wake cycles. However,influences from the endogenous circadian pacemaker independent from behaviors may also affect cardiac control. We investigate heartbeat dynamics in healthy subjects recorded throughout a 10-day protocol wherein the sleep/wake and behavior cycles are desynchronized from the endogenous circadian cycle,enabling assessment of circadian factors while controlling for behavior-related factors. We demonstrate that the scaling exponent characterizing temporal correlations in heartbeat dynamics over multiple time scales does exhibit a significant circadian rhythm with a sharp peak at the circadian phase corresponding to the period 9-11AM, and that this rhythm is independent from scheduled behaviors and mean heart rate. Our findings of strong circadian rhythms in the multi-scale heartbeat dynamics of healthy young subjects indicate that the underlying mechanism of cardiac regulation is strongly influenced by the endogenous circadian pacemaker. A similar circadian effect in vulnerable individuals with underlying cardiovascular disease would contribute to the morning peak of adverse cardiac events observed in epidemiological studies.

Ivanov, Plamen Ch.

2005-03-01

244

Circadian pacemaking in cells and circuits of the suprachiasmatic nucleus.  

PubMed

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 ([Ca(2+) ]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/[Ca(2+) ]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

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

2014-01-01

245

Left atrial spontaneous echo contrast in patients with permanent pacemakers.  

PubMed Central

OBJECTIVE: To determine the relations between left atrial appendage function, spontaneous echo contrast, and thromboembolism in patients with different modes of permanent pacemakers. PATIENTS AND METHODS: 88 patients with pacemaker implantation and 25 healthy controls in sinus rhythm had transoesophageal echocardiographic examination of the left atrial appendage. Left atrial size, appendage area, peak filling and emptying velocities of the atrial appendage, and the presence or absence of spontaneous echo contrast and thromboembolism were determined. The results in 63 patients with ventricular pacing (group 1, subdivided into subgroup 1A: 42 patients with sinus rhythm, and subgroup 1B: 21 patients with atrial fibrillation) were compared with those in 25 patients with synchronous pacing (group 2), and 25 normal control subjects (group 3). RESULTS: Patients with ventricular pacing had two distinct appendage flow patterns: well defined biphasic filling and emptying waves in subgroup 1A, and irregular very low filling and emptying waves in subgroup 1B. The ejection fraction of the left atrial appendage in subgroup 1A was significantly better than that in subgroup 1B (mean (SD) 40.6 (12.0)% v 7.6 (5.0)%, P < 0.0001). The spontaneous echo contrast was observed in 90% of subgroup 1B patients but in only 19% in subgroup 1A (P < 0.05) and was not found in groups 2 and 3 (P < 0.0001). There was a trend for increased prevalence of spontaneous echo contrast in subgroup 1A v group 2 (P = 0.053). Thrombi were detected in two cases, and cardiogenic embolism occurred in one case in subgroup 1B. All patients with spontaneous echo contrast had ventricular pacing. Multivariate analysis showed that atrial fibrillation was associated with occurrence of spontaneous echo contrast in patients with ventricular pacing (P = 0.005). CONCLUSIONS: The left atrial appendage ejection fraction was lower with ventricular pacing than with synchronous pacing. With ventricular pacing there was a trend towards increased prevalence of left atrial spontaneous echo contrast in patients in sinus rhythm, and a significantly increased prevalence in patients with atrial fibrillation. Images PMID:9391288

Lee, T. M.; Su, S. F.; Chien, K. L.; Lin, Y. J.; Chen, W. J.; Chen, M. F.; Liau, C. S.; Lee, Y. T.

1997-01-01

246

Rescue of a trafficking defective human pacemaker channel via a novel mechanism: roles of Src, Fyn, and Yes tyrosine kinases.  

PubMed

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

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

2009-10-30

247

Learning Physiology from Cardiac Surgery Patients  

NSDL National Science Digital Library

Rather than use animal models, a computer system was created using real cardiac patients. The program consisted of video clips, notes, diagrams, and a student workbook. Additionally, intro tutorials were created.

S C Nicol (University of Tasmania Physiology); Christian Narkowicz (University of Tasmania Physiology and Anatomy)

1998-06-01

248

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

SciTech Connect

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.

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

1989-11-01

249

Metabolic Syndrome and Cardiac Disease in Japanese Men: Applicability of the Concept of Metabolic Syndrome Defined by the National Cholesterol Education Program–Adult Treatment Panel III to Japanese Men—The Tanno and Sobetsu Study  

Microsoft Academic Search

Results of a 6-year follow-up study were used to determine whether the concept of and the criteria for metabolic syndrome as defined by the National Cholesterol Education Program–Adult Treatment Panel III (NCEP-ATP III) can be applied to Japanese men for prediction of the occurrence of cardiac disease. The subjects were 808 men who underwent mass health check-ups in 1993 and

Hiroshi Takeuchi; Shigeyuki Saitoh; Satoru Takagi; Hirofumi Ohnishi; Junichi Ohhata; Takeshi Isobe; Kazuaki Shimamoto

2005-01-01

250

Electromagnetic interference in cardiac rhythm management devices.  

PubMed

Clinicians caring for cardiac device patients with implanted pacemakers or cardioverter defibrillators (ICDs) are frequently asked questions by their patients concerning electromagnetic interference (EMI) sources and the devices. EMI may be radiated or conducted and may be present in many different forms including (but not limited to) radiofrequency waves, microwaves, ionizing radiation, acoustic radiation, static and pulsed magnetic fields, and electric currents. Manufacturers have done an exemplary job of interference protection with device features such as titanium casing, signal filtering, interference rejection circuits, feedthrough capacitors, noise reversion function, and programmable parameters. Nevertheless, EMI remains a real concern and a potential danger. Many factors influence EMI including those which the patient can regulate (eg, distance from and duration of exposure) and some the patient cannot control (eg, intensity of the EMI field, signal frequency). Potential device responses are many and range from simple temporary oversensing to permanent device damage Several of the more common EMI-generating devices and their likely effects on cardiac devices are considered in the medical, home, and daily living and work environments. PMID:15475813

Sweesy, Mark W; Holland, James L; Smith, Kerry W

2004-01-01

251

Outcomes in patients with high-degree atrioventricular block as the initial manifestation of cardiac sarcoidosis.  

PubMed

Although high-degree atrioventricular block (AVB) is a common initial manifestation of cardiac sarcoidosis, little is known about the outcomes. The aim of this study was to assess outcomes in patients with AVB as an initial manifestation of cardiac sarcoidosis compared with those in patients with ventricular tachyarrhythmia (VT) and/or heart failure (HF). Fifty-three consecutive patients with cardiac sarcoidosis, who had high-degree AVB (n = 22) or VT and/or HF (n = 31), were enrolled. The end point was defined as major adverse cardiac events, including cardiac death, ventricular fibrillation, sustained VT, and hospitalization for HF. Over a median follow-up period of 34 months, the outcomes of major adverse cardiac events were better in patients with high-degree AVB than in those with VT and/or HF (log-rank test, p = 0.046). However, this difference was due mainly to HF hospitalization. The outcomes of fatal cardiac events, including cardiac death, ventricular fibrillation, and sustained VT, were comparable between the 2 groups (log-rank test, p = 0.877). The fatal cardiac events in patients with high-degree AVB were not associated with the initiation of steroid treatment or left ventricular dysfunction. In conclusion, the outcomes of major adverse cardiac events are better in patients with high-degree AVB than in those with VT and/or HF. However, patients with high-degree AVB have a high rate of fatal cardiac events, similar to those with VT and/or HF. An indication for an implantable cardioverter-defibrillator, but not a pacemaker system, can be considered in patients with cardiac sarcoidosis manifested by high-degree AVB. PMID:25529542

Takaya, Yoichi; Kusano, Kengo Fukushima; Nakamura, Kazufumi; Ito, Hiroshi

2015-02-15

252

Anaesthetic management and complications of pacemaker implantation in dogs.  

PubMed

The aim of this study was to report the anaesthetic management and peri-anaesthetic complications of 57 dogs undergoing pacemaker implantation at a referral institution over 10?years (2002-2012). The median duration of the procedure was 135?minutes (range 25-260?minutes). Patients were classified as American Society of Anaesthesiologist (ASA) III (42 cases) and ASA IV (15 cases). Forty-three patients had third-degree atrioventricular block, and 14 patients had sick sinus syndrome. The anaesthetic protocol most frequently chosen was pethidine (41 cases), etomidate-midazolam (43 cases) and isoflurane in oxygen for maintenance (57 cases). Transthoracic external pacing was used (43 cases) until the internal pacing lead was implanted. Atracurium was administered (48 cases) and intermittent positive pressure ventilation was applied in 52 cases. Complications observed included hypothermia (19 cases) and hypotension (5 cases). Three patients died (5.8%, 95% CI 1.1% to 14.6%) within the first 48?hours after termination of anaesthesia. The outcome for this procedure in sick animals appeared generally good though a number of complications were documented. PMID:24958554

Sanchis-Mora, S; Viscasillas, J; Mathis, A; Palacios, C; Brodbelt, D C; Alibhai, H I

2014-09-27

253

KAYAK-? modulates circadian transcriptional feedback loops in Drosophila pacemaker neurons.  

PubMed

Circadian rhythms are generated by well-conserved interlocked transcriptional feedback loops in animals. In Drosophila, the dimeric transcription factor CLOCK/CYCLE (CLK/CYC) promotes period (per), timeless (tim), vrille (vri), and PAR-domain protein 1 (Pdp1) transcription. PER and TIM negatively feed back on CLK/CYC transcriptional activity, whereas VRI and PDP1 negatively and positively regulate Clk transcription, respectively. Here, we show that the ? isoform of the Drosophila FOS homolog KAYAK (KAY) is required for normal circadian behavior. KAY-? downregulation in circadian pacemaker neurons increases period length by 1.5 h. This behavioral phenotype is correlated with decreased expression of several circadian proteins. The strongest effects are on CLK and the neuropeptide PIGMENT DISPERSING FACTOR, which are both under VRI and PDP1 control. Consistently, KAY-? can bind to VRI and inhibit its interaction with the Clk promoter. Interestingly, KAY-? can also repress CLK activity. Hence, in flies with low KAY-? levels, CLK derepression would partially compensate for increased VRI repression, thus attenuating the consequences of KAY-? downregulation on CLK targets. We propose that the double role of KAY-? in the two transcriptional loops controlling Drosophila circadian behavior brings precision and stability to their oscillations. PMID:23175847

Ling, Jinli; Dubruille, Raphaëlle; Emery, Patrick

2012-11-21

254

Monocenter feasibility study of the MRI compatibility of the Evia pacemaker in combination with Safio S pacemaker lead  

PubMed Central

Background The purpose of this study was to evaluate the feasibility of the magnetic resonance (MR) conditional pacemaker (PM) system (Evia SR-T and DR-T with Safio S leads) under MR conditions. Methods Patients with standard PM indications and Evia PM were eligible for enrollment in this single center prospective non-randomized pilot study. Patients underwent MR of the brain and lower lumbar spine at 1.5 Tesla. Atrial (RA) und ventricular (RV) lead parameters (sensing, pacing threshold [PTH], pacing impedance) were assessed immediately before (baseline follow-up [FU]) and immediately after MRI (1st FU), after 1 month (2nd FU) and 3 months (3rd FU). The effect of MR on serious adverse device effect (SADE) free-rate, on atrial and ventricular sensing (AS/VS; mV) and atrial (RA) and ventricular (RV) pacing thresholds (PTH; V/0.4 ms) were investigated between baseline and 2nd FU. Continuous variables are expressed as mean?±?SD and were compared using paired Student’s t-test. A p?pacemakers led to MR imaging artifacts on diffusion weighted sequences of the brain, but did not affect other sequences (e.g. FLAIR and T2 weighted spin-echo images). Conclusion The use of the MR conditional Evia PM in a MR environment under predefined conditions is feasible. No MR related SADEs nor clinically relevant changes in device functions occurred. PMID:23009683

2012-01-01

255

Sinus node dysfunction following targeted disruption of the murine cardiac sodium channel gene Scn5a  

PubMed Central

We have examined sino-atrial node (SAN) function in hearts from adult mice with heterozygous targeted disruption of the Scn5a gene to clarify the role of Scn5a-encoded cardiac Na+ channels in normal SAN function and the mechanism(s) by which reduced Na+ channel function might cause sinus node dysfunction. Scn5a+/? mice showed depressed heart rates and occasional sino-atrial (SA) block. Their isolated peripheral SAN pacemaker cells showed a reduced Na+ channel expression and slowed intrinsic pacemaker rates. Wild-type (WT) and Scn5a+/? SAN preparations exhibited similar activation patterns but with significantly slower SA conduction and frequent sino-atrial conduction block in Scn5a+/? SAN preparations. Furthermore, isolated WT and Scn5a+/? SAN cells demonstrated differing correlations between cycle length, maximum upstroke velocity and action potential amplitude, and cell size. Small myocytes showed similar, but large myocytes reduced pacemaker rates, implicating the larger peripheral SAN cells in the reduced pacemaker rate that was observed in Scn5a+/? myocytes. These findings were successfully reproduced in a model that implicated iNa directly in action potential propagation through the SAN and from SAN to atria, and in modifying heart rate through a coupling of SAN and atrial cells. Functional alterations in the SAN following heterozygous-targeted disruption of Scn5a thus closely resemble those observed in clinical sinus node dysfunction. The findings accordingly provide a basis for understanding of the role of cardiac-type Na+ channels in normal SAN function and the pathophysiology of sinus node dysfunction and suggest new potential targets for its clinical management. PMID:15932895

Lei, Ming; Goddard, Catharine; Liu, Jie; Léoni, Anne-Laure; Royer, Anne; Fung, Simon S-M; Xiao, Guosheng; Ma, Aiqun; Zhang, Henggui; Charpentier, Flavien; Vandenberg, Jamie I; Colledge, William H; Grace, Andrew A; Huang, Christopher L-H

2005-01-01

256

Ionic Mechanisms of Pacemaker Activity in Spontaneously-contracting Atrial HL-1 Cells  

PubMed Central

Although normally absent, spontaneous pacemaker activity can develop in human atrium to promote tachyarrhythmias. HL-1 cells are immortalized atrial cardiomyocytes that contract spontaneously in culture, providing a model system of atrial cell automaticity. Using electrophysiologic recordings and selective pharmacologic blockers, we investigated the ionic basis of automaticity in atrial HL-1 cells. Both the sarcoplasmic reticulum (SR) Ca++ release channel inhibitor ryanodine and the SR Ca++ ATPase inhibitor thapsigargin slowed automaticity, supporting a role for intracellular Ca++ release in pacemaker activity. Additional experiments were performed to examine the effects of ionic currents activating in the voltage range of diastolic depolarization. Inhibition of the hyperpolarization-activated pacemaker current, If, by ivabradine significantly suppressed diastolic depolarization, with modest slowing of automaticity. Block of inward Na+ currents also reduced automaticity, while inhibition of T- and L-type Ca++ currents caused milder effects to slow beat rate. The major outward current in HL-1 cells is the rapidly activating delayed rectifier, IKr. Inhibition of IKr using dofetilide caused marked prolongation of APD and thus spontaneous cycle length. These results demonstrate a mutual role for both intracellular Ca++ release and sarcolemmal ionic currents in controlling automaticity in atrial HL-1 cells. Given that similar internal and membrane-based mechanisms also play a role in sinoatrial nodal cell pacemaker activity, our findings provide evidence for generalized conservation of pacemaker mechanisms among different types of cardiomyocytes. PMID:20881602

Yang, Zhenjiang; Murray, Katherine T.

2010-01-01

257

A Case of Transvenous Pacemaker Implantation in a 10-year-old Patient  

PubMed Central

Objective: The aim of this report was to discuss the type, timing, and surgical techniques of permanent pacemaker implantation in a juvenile patient. Patients: A 17-year-old girl with Down syndrome and congenital heart defects comprised of ventricular septal defects (VSD) and patent ductus arteriosus (PDA) suffered from postoperative complete atrioventricular block (AVB) when she was 7 months old. Methods and Results: An epicardial pacemaker was implanted just after the occurrence of complete AVB. Due to the pacing threshold of a ventricular lead not being good, the battery showed rapid depletion. Her generator had to be exchanged under general anesthesia every 2–3 years. When she was 10 years old, we implanted a permanent pacemaker transvenously by using cutdown, screw-in and subpectoral pocket techniques. She has shown a satisfactory outcome since then. Conclusion: Transvenous pacemaker implantation was safe and effective in our young patient without any complications. The timing of surgery and surgical technique are quite important for pacemaker implantation in juvenile patients.

Liu, Jiajia; Shimada, Yasuyuki

2013-01-01

258

Permanent transvenous pacemaker implantation in a patient with Cor triatriatum dextrum  

PubMed Central

Cor triatriatum dextrum is an extremely rare congenital heart abnormality in which the right atrium is separated into two chambers by a persistent fibrous membrane. A transvenous approach to place a dual-chamber pacemaker in such patients is technically challenging. We report the first case of a transvenous permanent pacemaker placement in a patient with cor triatriatum dextrum. An 87-year-old woman was diagnosed with paroxysmal atrial fibrillation. She was accidentally found to have cor triatriatum dextrum during the transesophageal echocardiography (TEE) prior to cardioversion. Later during her hospital stay, it was indicated to place a permanant pacemaker due to high grade atrioventricular block. After thorough reviewing TEE imagings, a transvenous catheter-based approach was decided feasible. Patient successfully received a dual chamber pacemaker through left subclavian venous approach. Furthermore in our case, using specially designed pacemaker leads and cautious intra-procedural maneuvering under fluoroscopic guidance ensured procedural success. In summary, a thorough pre-operative evaluation with transesophageal echocardiography is critical for the planning and eventual success of the transvenous placement of right-sided leads.

Xiang, Kun; Moukarbel, George V; Grubb, Blair

2015-01-01

259

Reliability and accuracy of sleep apnea scans in novel cardiac resynchronization therapy devices: an independent report of two cases.  

PubMed

Pacemaker apnea scan algorithms are able to screen for sleep apnea. We investigated whether these systems were able to accurately detect sleep-disordered breathing (SDB) in two patients from an outpatient clinic. The first patient suffered from ischemic heart failure and severe central sleep apnea (CSA) and underwent adaptive servoventilation therapy (ASV). The second patient suffered from dilated cardiomyopathy and moderate obstructive sleep apnea (OSA). Pacemaker read-outs did not match polysomnography (PSG) recordings well and overestimated the apnea-hypopnea index. However, ASV therapy-induced SDB improvements were adequately recognized by the apnea scan of the Boston Scientific INVIVE® cardiac resynchronization therapy pacemaker. Detection of obstructive respiratory events using impedance-based technology may underestimate the number of events, as frustrane breathing efforts induce impedance changes without significant airflow. By contrast, in the second case, apnea scan overestimated the number of total events and of obstructive events, perhaps owing to a very sensitive but less specific hypopnea definition and detection within the diagnostic algorithm of the device. These two cases show that a pacemaker apnea scan is able to reflect SDB, but PSG precision is not met by far. The device scan revealed the decline of SDB through ASV therapy for CSA in one patient, but not for OSA in the second case. To achieve reliable monitoring of SDB, further technical developments and clinical studies are necessary. PMID:24519661

Fox, Henrik; Nölker, Georg; Gutleben, Klaus-Jürgen; Bitter, Thomas; Horstkotte, Dieter; Oldenburg, Olaf

2014-03-01

260

A System for Pacemaker Treatment Advice1 Peter Lucas2 and Ruud Kuipers and Frederick Feith3  

E-print Network

of the human heart are controlled by a complicated system consisting of excitatory and conductive tis- sue optimised. This is called the pacemaker follow-up, which is normally done every 6 months after the initial 3 months follow-up. Pacemaker follow-up consists of the following steps: 1 Published in: R. L´opez de M

Lucas, Peter

261

Interaction between MRI RF field and pacemaker holders: A comparison between birdcage and TEM coils in 3 T systems  

Microsoft Academic Search

In this paper Birdcage and TEM coils operating at 128 MHz have been studied and compared in terms of their interaction with pacemaker holders. The pacemaker (PM) has been simulated as a copper box with a catheter constituted by an insulated copper wire with an uncapped tip and it has been placed inside a box model of the thorax. Electromagnetic

S. Pisa; P. Bernardi; A. Bicchieri; A. Fabrizi; E. Piuzzi

2011-01-01

262

Bright Light Induction of Strong (Type 0) Resetting of the Human Circadian Pacemaker  

NASA Astrophysics Data System (ADS)

The response of the human circadian pacemaker to light was measured in 45 resetting trials. Each trial consisted of an initial endogenous circadian phase assessment, a three-cycle stimulus which included 5 hours of bright light per cycle, and a final phase assessment. The stimulus induced strong (type 0) resetting, with responses highly dependent on the initial circadian phase of light exposure. The magnitude and direction of the phase shifts were modulated by the timing of exposure to ordinary room light, previously thought to be undetectable by the human pacemaker. The data indicate that the sensitivity of the human circadian pacemaker to light is far greater than previously recognized and have important implications for the therapeutic use of light in the management of disorders of circadian regulation.

Czeisler, Charles A.; Kronauer, Richard E.; Allan, James S.; Duffy, Jeanne F.; Jewett, Megan E.; Brown, Emery N.; Ronda, Joseph M.

1989-06-01

263

Pacemaker reuse for patients in resource poor countries: is something always better than nothing?  

PubMed

Cardiovascular disease is the most common cause of death across the globe. Large disparities in access to cardiovascular care exist in the world. An estimated one million people die each year due to lack of access to life saving pacemaker therapy. We discuss the concept of justice in health and health care as it relates to the use of refurbished pacemakers in patients in low- and middle- income countries, where financial circumstances severely limit access to brand new devices. Egalitarianism, utilitarianism, and justice as fairness are examined, as they relate to provision of re-processed pacemakers. This practice, since it holds promise to improve human functioning and capabilities, can be morally justified with some conditions: transparency, further research in is its safety and efficacy, and its impact on other needs and priorities in those countries. PMID:23217434

VanArtsdalen, Jamie; Goold, Susan Dorr; Kirkpatrick, James N; Goldman, Ed; Eagle, Kim; Crawford, Thomas

2012-01-01

264

[Migration of an epicardial pacemaker into the pouch of Douglas. Case report].  

PubMed

Migration of a permanent pacemaker generator from their intramuscular pocket to the abdominal cavity is a less frequent, but potentially life-threatening complication. The authors present the case of a 69-year-old woman, who visited the emergency department of the clinic, with complains of non-specific abdominal symptoms. Her past medical history included a complete atrioventricular block diagnosed in 2009 during the mitral valve replacement and since then she had an epicardial permanent pacemaker; the pulse generator was placed into an intramuscular pouch created in the left subcostal region. Surprisingly, radiologic examinations showed that the generator migrated into the pouch of Douglas. Considering patient safety, first a new intracardiac pacemaker was implanted and then the migrated device was removed surgically. The patient was discharged on the seventh postoperative day. Orv. Hetil., 2015, 156(4), 154-157. PMID:25597320

Barabás, János Imre; Hüttl, Tivadar; Hartyánszky, István; Fazekas, Levente; Oláh, Zoltán; Zima, Endre; Paulovich, Erzsébet; K?szegi, Andrea; Szabolcs, Zoltán

2015-01-01

265

Setups for in vitro assessment of RFID interference on pacemakers.  

PubMed

The aim of this study is to propose setups for in vitro assessment of RFID (radiofrequency identification) interference on pacemakers (PM). The voltage induced at the input stage of the PM by low-frequency (LF) and high-frequency (HF) RFID transmitters has been used to quantify the amount of the interference. A commercial PM was modified in order to measure the voltage at its input stage when exposed to a sinusoidal signal at 125 kHz and 13.56 MHz. At both frequencies, two antennas with different dimensions (diameter = 10 cm and 30 cm, respectively) were used to generate the interfering field, and the induced voltage was measured between the lead tip and the PM case (unipolar voltage), and between the tip and ring electrodes (bipolar voltage). The typical lead configurations adopted in similar studies or proposed by international standards, as well as lead paths closer to actual physiological implants were tested. At 125 kHz, the worst-case condition differs for the two antennas: the 10 cm antenna induced the highest voltage in the two-loop spiral configuration, whereas the 30 cm antenna in the 225 cm(2) loop configuration. At 13.56 MHz, the highest voltage was observed for both the antennas in the 225 cm(2) loop configuration. Bipolar voltages were found to be lower than the unipolar voltages induced in the same configurations, this difference being not as high as one could expect from theoretical considerations. The worst-case scenario, in terms of the induced voltage at the PM input stage, has been identified both for LF and HF readers, and for two sizes of transmitting antennas. These findings may provide the basis for the definition of a standard implant configuration and a lead path to test the EMI effects of LF and HF RFID transmitters on active implantable devices. PMID:23863617

Mattei, E; Censi, F; Delogu, A; Ferrara, A; Calcagnini, G

2013-08-01

266

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

PubMed

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

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

2014-08-01

267

Characterization of K+ currents underlying pacemaker potentials of fish gonadotropin-releasing hormone cells.  

PubMed

Endogenous pacemaker activities are important for the putative neuromodulator functions of the gonadotropin-releasing hormone (GnRH)-immunoreactive terminal nerve (TN) cells. We analyzed several types of voltage-dependent K+ currents to investigate the ionic mechanisms underlying the repolarizing phase of pacemaker potentials of TN-GnRH cells by using the whole brain in vitro preparation of fish (dwarf gourami, Colisa lalia). TN-GnRH cells have at least four types of voltage-dependent K+ currents: 1) 4-aminopyridine (4AP)-sensitive K+ current, 2) tetraethylammonium (TEA)-sensitive K+ current, and 3) and 4) two types of TEA- and 4AP-resistant K+ currents. A transient, low-threshold K+ current, which was 4AP sensitive and showed significant steady-state inactivation in the physiological membrane potential range (-40 to -60 mV), was evoked from a holding potential of -100 mV. This current thus cannot contribute to the repolarizing phase of pacemaker potentials. TEA-sensitive K+ current evoked from a holding potential of -100 mV was slowly activating, long lasting, and showed comparatively low threshold of activation. This current was only partially inactivated at steady state of -60 to -40 mV, which is equivalent to the resting membrane potential. TEA- and 4AP-resistant sustained K+ currents were evoked from a holding potential of -100 mV and were suggested to consist of two types, based on the analysis of activation curves. From the inactivation and activation curves, it was suggested that one of them with low threshold of activation may be partly involved in the repolarizing phase of pacemaker potentials. Bath application of TEA together with tetrodotoxin reversibly blocked the pacemaker potentials in current-clamp recordings. We conclude that the TEA-sensitive K+ current is the most likely candidate that contributes to the repolarizing phase of the pacemaker potentials of TN-GnRH cells. PMID:10036267

Abe, H; Oka, Y

1999-02-01

268

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

SciTech Connect

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.

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

269

Noninvasive localization of the site of origin of paced cardiac activation in human by means of a 3-D heart model  

Microsoft Academic Search

A recently developed heart-model-based localization approach is experimentally evaluated in noninvasively localizing the site of origin of cardiac activation in a patient with a pacemaker. The heart-torso model of the patient was constructed from the contrast ultrafast computed tomography images. The site of initial paced activation in the patient was quantitatively localized and compared with the tip position of the

Guanglin Li; Xin Zhang; Jie Lian; Bin He

2003-01-01

270

The Short Stature Homeobox 2 (Shox2)-bone Morphogenetic Protein (BMP) Pathway Regulates Dorsal Mesenchymal Protrusion Development and Its Temporary Function as a Pacemaker during Cardiogenesis.  

PubMed

The atrioventricular (AV) junction plays a critical role in chamber septation and transmission of cardiac conduction pulses. It consists of structures that develop from embryonic dorsal mesenchymal protrusion (DMP) and the embryonic AV canal. Despite extensive studies on AV junction development, the genetic regulation of DMP development remains poorly understood. In this study we present evidence that Shox2 is expressed in the developing DMP. Intriguingly, this Shox2-expressing domain possesses a pacemaker-specific genetic profile including Hcn4 and Tbx3. This genetic profile leads to nodal-like electrophysiological properties, which is gradually silenced as the AV node becomes matured. Phenotypic analyses of Shox2(-/-) mice revealed a hypoplastic and defectively differentiated DMP, likely attributed to increased apoptosis, accompanied by dramatically reduced expression of Bmp4 and Hcn4, ectopic activation of Cx40, and an aberrant pattern of action potentials. Interestingly, conditional deletion of Bmp4 or inhibition of BMP signaling by overexpression of Noggin using a Shox2-Cre allele led to a similar DMP hypoplasia and down-regulation of Hcn4, whereas activation of a transgenic Bmp4 allele in Shox2(-/-) background attenuated DMP defects. Moreover, the lack of Hcn4 expression in the DMP of mice carrying Smad4 conditional deletion and direct binding of pSmad1/5/8 to the Hcn4 regulatory region further confirm the Shox2-BMP genetic cascade in the regulation of DMP development. Our results reveal that Shox2 regulates DMP fate and development by controlling BMP signaling through the Smad-dependent pathway to drive tissue growth and to induce Hcn4 expression and suggest a temporal pacemaking function for the DMP during early cardiogenesis. PMID:25488669

Sun, Cheng; Yu, Diankun; Ye, Wenduo; Liu, Chao; Gu, Shuping; Sinsheimer, Nathan R; Song, Zhongchen; Li, Xihai; Chen, Chun; Song, Yingnan; Wang, Shusheng; Schrader, Laura; Chen, YiPing

2015-01-23

271

Infection control in cardiac surgery.  

PubMed

This report relates the results of a multifaceted, 4 year program directed toward reduction of infection in patients undergoing cardiac operations and extracorporeal circulation in a large teaching hospital. Retrospective analysis of all superficial and deep wound infections and prosthetic valve infections for the period of 1966 to 1970 and a prospective study of the period of 1970 to 1974 were made. The multifaceted program begun in 1970 consisted of (1) renovation of a cardiac operating room with incorporation of a high flow, vertical unidirectional ventilation system, (2) change in the gown and draping material for improvement of barriers to bacteriologic shedding, (3) frequent steam sterilization of prosthetic valves, (4) routine use of an antistaphylococcal agent in patients receiving valve replacement, and (5) an unannounced bacteriologic monitoring program of the cardiac operating room personnel. Studies of airborne particulates and bacteria and adequacy of skin preparation and hair removal also were conducted. The studies showed that (1) a high-flow HEPA filtered vertical ventilation system and altered operating room clothing reduced the concentration of airborne particles and the concentration of bacteria at the wound by a factor of 10 compared to conventional operating rooms, (2) the incidence of markedly contaminated scrubbed and unscrubbed hands decreased, (3) shedders and carriers were identified, and (4) current patient skin preparation and hair removal practices were satisfactory. The results of the program were a reduction of the deep wound infection rate from 2.9 to 0.6 percent (p less than 0.01) and a concomitant total wound infection decrease from 6.6 to 3.3 percent. Prosthetic valve infection rates decreased fourfold, from 5.6 to 1.4 percent. It is concluded that careful attention to possible endogenous sources of infection from the patient and a multifaceted program directed to exogenous sources of infection can lower infection rates in cardiac surgical patients. PMID:1246694

Clark, R E; Amos, W C; Higgins, V; Bemberg, K F; Weldon, C S

1976-01-01

272

Patients with pacemaker or implantable cardioverter-defibrillator.  

PubMed

The preparation of patients with a cardiac implantable electronic device (CIED) for the perioperative period necessitates familiarity with recommendations from the American Society of Anesthesiologists and Heart Rhythm Society. Even clinicians who are not CIED experts should understand the indications for implantation, as well as the basic functions, operations, and limitations of these devices. Before any scheduled procedure, proper CIED function should be verified and a specific CIED prescription obtained. Acquiring the requisite knowledge base and developing the systems to competently manage the CIED patient ensures safe and efficient perioperative care. PMID:24182719

Schulman, Peter M; Rozner, Marc A; Sera, Valerie; Stecker, Eric C

2013-11-01

273

Follower Neurons in Lobster (Panulirus interruptus) Pyloric Network Regulate Pacemaker Period in Complementary Ways  

E-print Network

Follower Neurons in Lobster (Panulirus interruptus) Pyloric Network Regulate Pacemaker Period November 2002 Weaver, Adam L. and Scott L. Hooper. Follower neurons in lobster (Panulirus interruptus this technique to study cycle period control in the rhythmic pyloric network of the lobster, Panulirus

Hooper, Scott

274

Extreme Events as Pacemaker of Adaptation to Climate Change1 William R. Travis  

E-print Network

1 Extreme Events as Pacemaker of Adaptation to Climate Change1 William R. Travis Department are thought of as propelling adaptation to climate change (Füssel, 2007; IPCC, 2012). In the simplest effect of extremes is now often invoked for adaptation to a changing climate: an underlying trend in, say

Neff, Jason

275

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

NASA Astrophysics Data System (ADS)

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

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

2011-02-01

276

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

E-print Network

"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

Zucker, Robert S.

277

Neurotensin Modulates Pacemaker Activity in Interstitial Cells of Cajal from the Mouse Small Intestine  

PubMed Central

Neurotensin, a tridecapeptide localized in the gut to discrete enteroendocrine cells of the small bowel mucosa, is a hormone that plays an important role in gastrointestinal secretion, growth, and motility. Neurotensin has inhibitory and excitatory effects on peristaltic activity and produces contractile and relaxant responses in intestinal smooth muscle. Our objective in this study is to investigate the effects of neurotensin in small intestinal interstitial cells of Cajal (ICC) and elucidate the mechanism. To determine the electrophysiological effects of neurotensin on ICC, whole-cell patch clamp recordings were performed in cultured ICC from the small intestine. Exposure to neurotensin depolarized the membrane of pacemaker cells and produced tonic inward pacemaker currents. Only neurotensin receptor1 was identified when RT-PCR and immunocytochemistry were performed with mRNA isolated from small intestinal ICC and c-Kit positive cells. Neurotensin-induced tonic inward pacemaker currents were blocked by external Na+- free solution and in the presence of flufenamic acid, an inhibitor of non-selective cation channels. Furthermore, neurotensin-induced action is blocked either by treatment with U73122, a phospholipase C inhibitor, or thapsigargin, a Ca2+-ATPase inhibitor in ICC. We found that neurotensin increased spontaneous intracellular Ca2+ oscillations as seen with fluo4/AM recording. These results suggest that neurotensin modulates pacemaker currents via the activation of non-selective cation channels by intracellular Ca2+-release through neurotensin receptor1. PMID:22441675

Lee, Jun; Kim, Young Dae; Park, Chan Guk; Kim, Man Yoo; Chang, In Yeoub; Zuo, Dong Chuan; Shahi, Pawan Kumar; Choi, Seok; Yeum, Cheol Ho; Jun, Jae Yeoul

2012-01-01

278

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

Microsoft Academic Search

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

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

1995-01-01

279

Tetrodotoxin-resistant persistent Na+ current underlying pacemaker potentials of fish gonadotrophin-releasing hormone neurones.  

PubMed Central

1. Gonadotrophin-releasing hormone (GnRH)-immunoreactive terminal nerve (TN) cells show endogenous regular beating discharges, which may be related to their putative neuromodulator functions. The ionic mechanism underlying the pacemaker potential was studied using intracellular and patch-pipette current clamp recordings from a whole brain in vitro preparation of a small fish brain. 2. The pacemaker potentials were resistant to 1.5-3 microM tetrodotoxin (TTX) and were not affected by Ca2+ channel blockers (amiloride, Ni2+, Co2+, Cd2+) or in Ca(2+)-free solution. In contrast, the pacemaker potentials were readily blocked by substituting tetramethylammonium or choline for Na+ in the perfusing solution, and the resting membrane potential became more hyperpolarized than the control level. 3. The present results suggest that the TTX-resistant persistent Na+ current, INa(slow), supplies the persistent depolarizing drive and plays an important role in the generation of pacemaker potentials in TN GnRH cells. PMID:7730975

Oka, Y

1995-01-01

280

Paradoxical induction of cross-talk in a dual chamber pacemaker by increasing the ventricular output.  

PubMed

Cross-talk was induced in a unipolar DDD pacemaker by increasing the output of the ventricular channel. Oversensing by the ventricular channel was probably due to the detection of a relatively large summation signal consisting of the afterpotential and the superimposed activity from the atrial stimulus. PMID:11388115

Barold, S S

2001-05-01

281

Beating irregularity of single pacemaker cells isolated from the rabbit sinoatrial node.  

PubMed Central

Single pacemaker heart cells discharge irregularly. Data on fluctuations in interbeat interval of single pacemaker cells isolated from the rabbit sinoatrial node are presented. The coefficient of variation of the interbeat interval is quite small, approximately 2%, even though the coefficient of variation of diastolic depolarization rate is approximately 15%. It has been hypothesized that random fluctuations in interbeat interval arise from the stochastic behavior of the membrane ionic channels. To test this hypothesis, we constructed a single channel model of a single pacemaker cell isolated from the rabbit sinoatrial node, i.e., a model into which the stochastic open-close kinetics of the individual membrane ionic channels are incorporated. Single channel conductances as well as single channel open and closed lifetimes are based on experimental data from whole cell and single channel experiments that have been published in the past decade. Fluctuations in action potential parameters of the model cell are compared with those observed experimentally. It is concluded that fluctuations in interbeat interval of single sinoatrial node pacemaker cells indeed are due to the stochastic open-close kinetics of the membrane ionic channels. PMID:8312495

Wilders, R; Jongsma, H J

1993-01-01

282

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

PubMed Central

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

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

2014-01-01

283

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

PubMed

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

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

2014-10-01

284

[Detection and therapy of respiratory dysfunction by implantable (cardiac) devices].  

PubMed

Sleep-disordered breathing (SDB) represents a common comorbidity in cardiac patients. The prevalence of obstructive sleep apnea (OSA) and central sleep apnea (CSA) is very high, particularly in patients with heart rhythm disorders and heart failure (HF). Patients with pacemakers (PM) and implantable defibrillators (ICD) including cardiac resynchronization therapy (CRT) show SDB prevalences up to 75%. However, some modern PM, ICD and CRT devices allow the detection of SDB via transthoracic impedance analysis with high sensitivity compared to polysomnographic (PSG) controls. Thus, this method could be of relevance in screening and monitoring SDB in patients with implantable cardiac devices. Preliminary studies demonstrated the possibility to treat OSA in selected patients by stimulation of the cranial nerves, especially the hypoglossal nerve. However, this requires extensive diagnostics and advanced surgical approaches including many medical disciplines and is not part of this review article. However, unilateral and transvenous stimulation of the phrenic nerve to treat central sleep apnea and Cheyne-Stokes respiration in HF patients in particular can be performed by cardiologists. This article summarizes preliminary data on the results of this promising therapy. PMID:24638158

Fox, H; Oldenburg, O; Nölker, G; Horstkotte, D; Gutleben, K-J

2014-02-01

285

Teaching Cardiac Electrophysiology Modeling to Undergraduate Students: Laboratory Exercises and GPU Programming for the Study of Arrhythmias and Spiral Wave Dynamics  

ERIC Educational Resources Information Center

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…

Bartocci, Ezio; Singh, Rupinder; von Stein, Frederick B.; Amedome, Avessie; Caceres, Alan Joseph J.; Castillo, Juan; Closser, Evan; Deards, Gabriel; Goltsev, Andriy; Ines, Roumwelle Sta.; Isbilir, Cem; Marc, Joan K.; Moore, Diquan; Pardi, Dana; Sadhu, Sandeep; Sanchez, Samuel; Sharma, Pooja; Singh, Anoopa; Rogers, Joshua; Wolinetz, Aron; Grosso-Applewhite, Terri; Zhao, Kai; Filipski, Andrew B.; Gilmour, Robert F., Jr.; Grosu, Radu; Glimm, James; Smolka, Scott A.; Cherry, Elizabeth M.; Clarke, Edmund M.; Griffeth, Nancy; Fenton, Flavio H.

2011-01-01

286

Contemporary pacemaker and ICD lead management: techniques for lead extraction.  

PubMed

With the increasing utilization of cardiac implantable electronic devices, the ability to extract leads using the transvenous approach has become important. Devices that are infected and leads that pose a risk to the patient by causing damage to cardiovascular structures, interference with device function or life-threatening arrhythmias should be removed. While the majority of extractions are performed through the vein of implantation, other approaches, such as the femoral approach, are required in some circumstances. Simple traction may be successful in removing the lead in relatively new (<1 year) implants. Older devices invariably require devices such as locking stylets and simple or powered sheaths. With current techniques, complete lead extraction can be achieved in >90% of cases with a major complication rate of <2% and mortality rate of <1%. Transvenous lead extraction should be performed only by experienced operators with the resources to address life-threatening complications. PMID:22908921

Madhavan, Malini; Swale, Matthew J; Gard, Joseph J; Hayes, David L; Asirvatham, Samuel J

2012-07-01

287

Cardiac gated ventilation  

NASA Astrophysics Data System (ADS)

There are several theoretic advantages to synchronizing positive pressure breaths with the cardiac cycle, including the potential for improving distribution of pulmonary and myocardial blood flow and enhancing cardiac output. We evaluated the effects of synchronizing respiration to the cardiac cycle using a programmable ventilator and electron beam CT (EBCT) scanning. The hearts of anesthetized dogs were imaged during cardiac gated respiration with a 50msec scan aperture. Multislice, short axis, dynamic image data sets spanning the apex to base of the left ventricle were evaluated to determine the volume of the left ventricular chamber at end-diastole and end-systole during apnea, systolic and diastolic cardiac gating. We observed an increase in cardiac output of up to 30% with inspiration gated to the systolic phase of the cardiac cycle in a nonfailing model of the heart.

Hanson, C. William, III; Hoffman, Eric A.

1995-05-01

288

Cardiac gated ventilation  

SciTech Connect

There are several theoretic advantages to synchronizing positive pressure breaths with the cardiac cycle, including the potential for improving distribution of pulmonary and myocardial blood flow and enhancing cardiac output. The authors evaluated the effects of synchronizing respiration to the cardiac cycle using a programmable ventilator and electron beam CT (EBCT) scanning. The hearts of anesthetized dogs were imaged during cardiac gated respiration with a 50 msec scan aperture. Multi slice, short axis, dynamic image data sets spanning the apex to base of the left ventricle were evaluated to determine the volume of the left ventricular chamber at end-diastole and end-systole during apnea, systolic and diastolic cardiac gating. The authors observed an increase in cardiac output of up to 30% with inspiration gated to the systolic phase of the cardiac cycle in a non-failing model of the heart.

Hanson, C.W. III [Hospital of the Univ. of Pennsylvania, Philadelphia, PA (United States). Dept. Anesthesia; Hoffman, E.A. [Univ. of Iowa College of Medicine, Iowa City, IA (United States). Div. of Physiologic Imaging

1995-12-31

289

Cardiac rehabilitation in the elderly.  

PubMed

Coronary heart disease (CHD) is the leading cause of death worldwide. Advanced age is associated with a higher prevalence of CHD as well as increased morbidity and mortality. One key vulnerability relates to the fact that older individuals are generally among the least fit, least active cohort and at increased risk of complications after an acute cardiac event and/or major surgery. There is ample evidence to demonstrate the beneficial effects of exercised-based cardiac rehabilitation (CR) programs on improving functional capacity and other indices of cardiovascular (CV) health. Although the predominant number of studies is in middle-aged patients, there is an escalating amount of new information that establishes the cardioprotective role of CR and, in particular, structured exercise therapy (ET) among the elderly. The present review summarizes the current data available regarding CR and ET and its salutary impact on today's growing population of older adults with CHD. PMID:25216614

Menezes, Arthur R; Lavie, Carl J; Forman, Daniel E; Arena, Ross; Milani, Richard V; Franklin, Barry A

2014-01-01

290

Initiation of atrial fibrillation by interaction of pacemakers with geometrical constraints.  

PubMed

Atrial fibrillation (AF) is the most common arrhythmia of the heart in industrialized countries. Its generation and the transitory behavior of paroxysmal AF are still not well understood. In this work we examine the interaction of two activation sources via an isthmus as possible cause for the initiation of fibrillation episodes. For this study, the electrophysiological model of Bueno-Orovio, Cherry and Fenton is adapted to atrial electrophysiology, both for physiological and electrophysiologically remodeled conditions due to AF. We show that the interaction of the pacemakers, combined with the geometrical constraints of the isthmus, can produce fibrillatory-type irregularities, which we quantify by the loss of spatial phase coherence in the transmembrane voltage. Transitions to irregular behavior occur when the frequencies of the pacemakers exceed certain thresholds, suggesting that AF episodes are initiated by frequency changes of the activating sources (sinus node, ectopic focus). PMID:25451519

Lenk, Claudia; Weber, Frank M; Bauer, Martin; Einax, Mario; Maass, Philipp; Seeman, Gunnar

2015-02-01

291

Cleft lip, nose, and palate: the nasal septum as the pacemaker for midfacial growth.  

PubMed

The need to be aware of the dynamics of cartilage development and growth is encountered by surgeons whenever they attempt to correct craniofacial defects such as unilateral or bilateral cleft lip/cleft palate or midfacial injuries after trauma. Within the craniofacial region, the nasal septal cartilage and the sphenoethmoidal and sphenooccipital cranial synchondroses are distinguished from other craniofacial cartilages in possessing intrinsic growth potential. Indeed, growth of the nasal septal cartilage outstrips the growth of other skeletal and soft tissues in the midface to such an extent that it is the pacemaker for growth of the face and anterior portion of the skull. We revisit and reinforce the importance of the nasal septum as pacemaker with analysis of 3 classes of evidence: in vivo growth of the nasal septum in nonhuman mammalian models; composition and in vitro growth of nasal septal cartilage or chondrocytes; and experience from the surgical repair of unilateral or bilateral facial clefts. PMID:23022023

Hall, Brian K; Precious, David S

2013-04-01

292

Morphology of rostral medullary neurons with intrinsic pacemaker activity in the rat.  

PubMed

Neurons with regular ongoing activity attributable to intrinsic pacemaker properties were recorded in coronal tissue slices within the nucleus reticularis rostroventrolateralis of the rat medulla oblongata (RVL). The cells were injected with horseradish peroxidase or Lucifer yellow and their dendritic and proximal axonal characteristics were investigated (n = 15). These small-to-medium-sized neurons had a simple dendritic arborization (3-6 primary dendrites branching up to 3 times) apparently confined within the limits of nucleus RVL and with limited extension in the rostrocaudal direction. Their axons originated either from the cell body or from a primary dendrite and coursed in a dorsomedial direction without giving rise to local arborizations. It is concluded that RVL pacemaker neurons, presumed to represent a non-adrenergic class of sympathoexcitatory premotor neurons, exhibit characteristics reminiscent of the archetypal 'reticular core' neurons. PMID:1718558

Sun, M K; Stornetta, R L; Guyenet, P G

1991-08-01

293

Developmental change in the voltage-dependence of the pacemaker current, if, in rat ventricle cells.  

PubMed

Myocytes were isolated from newborn and adult rat ventricle. Using the whole-cell patch clamp, the two cell populations were compared for the presence of the hyperpolarization-activated pacemaker current if. As in other mammalian species, the threshold voltage in acutely dissociated adult rat myocytes was extremely negative (-113 +/- 5 mV; n=12). In contrast, threshold in newborn cells was relatively positive, regardless of whether measured in acutely dissociated (-72 +/- 2 mV; n=6) or cultured cells (-70 +/- 2 mV; n=9). Current density was not reduced in the adult. These results suggest that with development the ventricle assumes its non-pacemaker function, at least in part, by a shift of the voltage dependence of if outside the physiological range. PMID:9000433

Robinson, R B; Yu, H; Chang, F; Cohen, I S

1997-02-01

294

Comparison of activity sensors and algorithms for rate-responsive pacemakers using ambulatory monitoring  

Microsoft Academic Search

Various methods have been used to control rate-responsive pacemaker rates using activity as controlling signal. The purpose of this study was to compare the performance of two activity sensors (case-mounted piezoelectric and accelerometer), two bandpass filters (1-4 Hz and 15 Hz), and two signal processing algorithms (threshold counting and integration). Data were collected in 26 normal human subjects during protocols

D. Cooper

1993-01-01

295

Slow and rapid responses to CW and pulsed microwave radiation by individual Aplysia pacemakers.  

PubMed

Specific absorption rates (SARs) of microwave energy that altered firing rates were determined for individual pacemaker neurons in the abdominal ganglion of Aplysia californica. A stripline apparatus provided both for artifact-free recording of transmembrane potentials and for precise determination of the rate of absorption of microwave energy. Exposure for two to three minutes at an SAR of only a few mW/g was capable of changing the firing rate of some pacemakers. Two types of responses were observed. The response that was seen in all neurons developed slowly, reaching a steady state in one to three minutes. The other response was seen in a few neurons and occurred within five seconds from the onset of irradiation. Similar responses were obtained for two microwave frequencies, 1.5 and 2.45 GHz. Pulsed radiation induced rapid changes of firing rate more readily than did CW radiation at the same SAR. A convective heating scheme was used to study the effects of temperature changes on the pacemakers' firing rates. Since all of the responses are not readily explained by general heating of the preparation, alternate mechanisms are suggested for the observed effects. PMID:213605

Seaman, R L; Wachtel, H

1978-03-01

296

Sexual Interactions Influence the Molecular Oscillations in DN1 Pacemaker Neurons in Drosophila melanogaster  

PubMed Central

Circadian rhythms can synchronize to environmental time cues, such as light, temperature, humidity, and food availability. Previous studies have suggested that these rhythms can also be entrained by social interactions. Here, we used Drosophila melanogaster as a model to study the influence of socio-sexual interactions on the circadian clock in behavior and pacemaker neurons. If two flies of opposite sex were paired and kept in a small space, the daily activity patterns of the two flies were clearly different from the sum of the activity of single male and female flies. Compared with single flies, paired flies were more active in the night and morning, were more active during females’ active phase, and were less active during males’ active phase. These behavioral phenotypes are related to courtship behavior, but not to the circadian clock. Nevertheless, in male-female pairs of flies with clocks at different speeds (wild-type and perS flies), clock protein cycling in the DN1 pacemaker neurons in the male brain were slightly influenced by their partners. These results suggest that sexual interactions between male-female couples can serve as a weak zeitgeber for the DN1 pacemaker neurons, but the effect is not sufficient to alter rhythms of behavioral activity. PMID:24367668

Hanafusa, Shiho; Kawaguchi, Tomoaki; Umezaki, Yujiro; Tomioka, Kenji; Yoshii, Taishi

2013-01-01

297

Biventricular Pacing (Cardiac Resynchronization Therapy)  

PubMed Central

Executive Summary Issue In 2002, (before the establishment of the Ontario Health Technology Advisory Committee), the Medical Advisory Secretariat conducted a health technology policy assessment on biventricular (BiV) pacing, also called cardiac resynchronization therapy (CRT). The goal of treatment with BiV pacing is to improve cardiac output for people in heart failure (HF) with conduction defect on ECG (wide QRS interval) by synchronizing ventricular contraction. The Medical Advisory Secretariat concluded that there was evidence of short (6 months) and longer-term (12 months) effectiveness in terms of cardiac function and quality of life (QoL). More recently, a hospital submitted an application to the Ontario Health Technology Advisory Committee to review CRT, and the Medical Advisory Secretariat subsequently updated its health technology assessment. Background Chronic HF results from any structural or functional cardiac disorder that impairs the ability of the heart to act as a pump. It is estimated that 1% to 5% of the general population (all ages) in Europe have chronic HF. (1;2) About one-half of the patients with HF are women, and about 40% of men and 60% of women with this condition are aged older than 75 years. The incidence (i.e., the number of new cases in a specified period) of chronic HF is age dependent: from 1 to 5 per 1,000 people each year in the total population, to as high as 30 to 40 per 1,000 people each year in those aged 75 years and older. Hence, in an aging society, the prevalence (i.e., the number of people with a given disease or condition at any time) of HF is increasing, despite a reduction in cardiovascular mortality. A recent study revealed 28,702 patients were hospitalized for first-time HF in Ontario between April 1994 and March 1997. (3) Women comprised 51% of the cohort. Eighty-five percent were aged 65 years or older, and 58% were aged 75 years or older. Patients with chronic HF experience shortness of breath, a limited capacity for exercise, high rates of hospitalization and rehospitalization, and die prematurely. (2;4) The New York Heart Association (NYHA) has provided a commonly used functional classification for the severity of HF (2;5): Class I: No limitation of physical activity. No symptoms with ordinary exertion. Class II: Slight limitations of physical activity. Ordinary activity causes symptoms. Class III: Marked limitation of physical activity. Less than ordinary activity causes symptoms. Asymptomatic at rest. Class IV: Inability to carry out any physical activity without discomfort. Symptoms at rest. The National Heart, Lung, and Blood Institute estimates that 35% of patients with HF are in functional NYHA class I; 35% are in class II; 25%, class III; and 5%, class IV. (5) Surveys (2) suggest that from 5% to 15% of patients with HF have persistent severe symptoms, and that the remainder of patients with HF is evenly divided between those with mild and moderately severe symptoms. Overall, patients with chronic, stable HF have an annual mortality rate of about 10%. (2) One-third of patients with new-onset HF will die within 6 months of diagnosis. These patients do not survive to enter the pool of those with “chronic” HF. About 60% of patients with incident HF will die within 3 years, and there is limited evidence that the overall prognosis has improved in the last 15 years. To date, the diagnosis and management of chronic HF has concentrated on patients with the clinical syndrome of HF accompanied by severe left ventricular systolic dysfunction. Major changes in treatment have resulted from a better understanding of the pathophysiology of HF and the results of large clinical trials. Treatment for chronic HF includes lifestyle management, drugs, cardiac surgery, or implantable pacemakers and defibrillators. Despite pharmacologic advances, which include diuretics, angiotensin-converting enzyme inhibitors, beta-blockers, spironolactone, and digoxin, many patients remain symptomatic on maximally tolerated doses. The Technology Owing to the limitations of drug therap

2005-01-01

298

Cardiac Procedures and Surgeries  

MedlinePLUS

Cardiac Procedures and Surgeries Updated:Oct 24,2014 If you've had a heart attack, you may have already had certain procedures to ... artery disease (CAD) you have. Cardiac Procedures and Surgeries Angioplasty Also known as Percutaneous Coronary Interventions [PCI], ...

299

Cardiac sarcoidosis: contemporary review.  

PubMed

Cardiac sarcoidosis can occur in up to 25% of patients with sarcoidosis in other organ systems and may present with conduction abnormalities, ventricular arrhythmias, or heart failure. This review will summarize the state of current knowledge and key questions that remain to be answered. Because cardiac sarcoidosis is a rare, complex disease, the most meaningful research will include interdisciplinary, multicenter collaborations. PMID:25231794

Kron, Jordana; Ellenbogen, Kenneth A

2015-01-01

300

Maternal Cardiac Arrest: A Practical and Comprehensive Review  

PubMed Central

Cardiac arrest during pregnancy is a dedicated chapter in the American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care; however, a robust maternal cardiac arrest knowledge translation strategy and emergency response plan is not usually the focus of institutional emergency preparedness programs. Although maternal cardiac arrest is rare, the emergency department is a high-risk area for receiving pregnant women in either prearrest or full cardiac arrest. It is imperative that institutions review and update emergency response plans for a maternal arrest. This review highlights the most recent science, guidelines, and recommended implementation strategies related to a maternal arrest. The aim of this paper is to increase the understanding of the important physiological differences of, and management strategies for, a maternal cardiac arrest, as well as provide institutions with the most up-to-date literature on which they can build emergency preparedness programs for a maternal arrest. PMID:23956861

Jeejeebhoy, Farida M.; Morrison, Laurie J.

2013-01-01

301

Cardiac Resynchronization Therapy Upregulates Cardiac Autonomic Control  

PubMed Central

Objective: To determine the effect of cardiac resynchronization therapy (CRT) on sympathetic nervous function in heart failure (HF). Background: Neurohormonal dysregulation and cardiac autonomic dysfunction are associated with HF and contribute to HF progression and its poor prognosis. We hypothesized that mechanical resynchronization improves cardiac sympathetic function in HF. Methods: Sixteen consecutive patients receiving CRT for advanced cardiomyopathy and 10 controls were included in this prospective study. NYHA class, 6-minute walk distance, echocardiographic parameters, plasma norepinephrine (NE) were assessed at baseline, 3-month and 6-month follow-up. Cardiac sympathetic function was determined by 123iodine metaiodobenzylguanidine (123I-MIBG) scintigraphy and 24-hour ambulatory electrocardiography. Results: Along with improvement in NYHA class (3.1 ± 0.3 to 2.1 ± 0.4, P < 0.001) and LVEF (23 ± 6% to 33 ± 12%, P < 0.001 delayed heart/mediastinum (H/M) 123 I-MIBG ratio increased significantly (1.8 ± 0.7 to 2.1 ± 0.6, P = 0.04) while the H/M 123I-MIBG washout rate decreased significantly (54 ± 25% to 34± 24%, P = 0.01) from baseline to 6-month follow-up. The heart rate variability (HRV) measured in SD of normal-to-normal intervals also increased significantly from baseline (82 ± 30 ms) to follow-up (111 ± 32 ms, P = 0.04). The improvement in NYHA after CRT was significantly associated with baseline 123I-MIBG H/M washout rate (r = 0.65, P = 0.03). The improvement in LVESV index was associated with baseline 123I-MIBG delayed H/M ratio (r = ?0.67, P = 0.02) and H/M washout rate (r = 0.65, P = 0.03). Conclusion: After CRT, improvements in cardiac symptoms and LV function were accompanied by rebalanced cardiac autonomic control as measured by 123I-MIBG and HRV. PMID:18479331

CHA, YONG-MEI; OH, JAE; MIYAZAKI, CHINAMI; HAYES, DAVID L.; REA, ROBERT F.; SHEN, WIN-KUANG; ASIRVATHAM, SAMUEL J.; KEMP, BRAD J.; HODGE, DAVID O.; CHEN, PENG-SHENG; CHAREONTHAITAWEE, PANITHAYA

2009-01-01

302

Cardiac Hegemony of Senescence  

PubMed Central

Cardiac senescence and age-related disease development have gained general attention and recognition in the past decades due to increased accessibility and quality of health care. The advancement in global civilization is complementary to concerns regarding population aging and development of chronic degenerative diseases. Cardiac degeneration has been rigorously studied. The molecular mechanisms of cardiac senescence are on multiple cellular levels and hold a multilayer complexity level, thereby hampering development of unambiguous treatment protocols. In particular, the synergistic exchange of the senescence phenotype through a senescence secretome between myocytes and stem cells appears complicated and is of great future therapeutic value. The current review article will highlight hallmarks of senescence, cardiac myocyte and stem cell senescence, and the mutual exchange of senescent secretome. Future cardiac cell therapy approaches require a comprehensive understanding of myocardial senescence to improve therapeutic efficiency as well as efficacy. PMID:24349878

Siddiqi, Sailay; Sussman, Mark A.

2013-01-01

303

Cardiac Hegemony of Senescence.  

PubMed

Cardiac senescence and age-related disease development have gained general attention and recognition in the past decades due to increased accessibility and quality of health care. The advancement in global civilization is complementary to concerns regarding population aging and development of chronic degenerative diseases. Cardiac degeneration has been rigorously studied. The molecular mechanisms of cardiac senescence are on multiple cellular levels and hold a multilayer complexity level, thereby hampering development of unambiguous treatment protocols. In particular, the synergistic exchange of the senescence phenotype through a senescence secretome between myocytes and stem cells appears complicated and is of great future therapeutic value. The current review article will highlight hallmarks of senescence, cardiac myocyte and stem cell senescence, and the mutual exchange of senescent secretome. Future cardiac cell therapy approaches require a comprehensive understanding of myocardial senescence to improve therapeutic efficiency as well as efficacy. PMID:24349878

Siddiqi, Sailay; Sussman, Mark A

2013-12-01

304

Arrhythmias, sudden cardiac death and incapacitation of pilots.  

PubMed

Inflight medical emergencies occur at a rate of 20 to 100 per million passengers, with a death rate of 0.1 to 1 per million. Cardiac, neurologic, and respiratory complaints comprise the more serious emergencies, as defined by aircraft diversion or use of ground-based medical assistance. In this paper, we review changes seen in the resting electrocardiogram in normal individuals exposed to high altitude, alongside important implications for patients with heart diseases in high altitude exposures and the possible effects of high altitude to permanent cardiac pacemakers. Arrhythmias in pilots and public safety are revisited together with the guidelines of the Joint Aviation Requirements (JAR) in Europe. The situation of Military flights is also discussed. Physicians ought to become knowledgeable about the specific medical job standards for their patients when asked to render opinions regarding fitness to fly. A database must be established to obtain prospective data that defines the risk of accidents in patients who are or were being treated for arrhythmias. Current guidelines could then be updated and revised as appropriate. PMID:19050752

Mantziari, L; Styliadis, C; Kourtidou-Papadeli, C; Styliadis, I

2008-08-01

305

Molecular Basis of Cardiac Myxomas  

PubMed Central

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

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

2014-01-01

306

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

PubMed Central

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

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

2012-01-01

307

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

PubMed

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

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

2014-01-01

308

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

SciTech Connect

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.

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

309

Hypoxia-activated Ca2+ currents in pacemaker neurones of rat rostral ventrolateral medulla in vitro.  

PubMed Central

We examined the effects of brief periods of hypoxia or application of cyanide on the discharge and membrane properties of medullary pacemaker neurones in slices of the rostral ventrolateral reticular nucleus (RVL) of the medulla oblongata of rats. Stable intracellular recordings were obtained from seventy-nine neurones within the RVL which exhibited spontaneous rhythmic discharge in the absence of excitatory postsynaptic potentials (EPSPs). The membrane potential cycles of these neurones could be reset with an evoked spike without eliciting EPSPs or inhibitory postsynaptic potentials and hence met criteria of RVL pacemaker neurones. Hypoxia, produced by reducing O2 from 95 to 20% for 40 s or exposure to cyanide (30-300 microM for 40 s), reversibly increased neuronal discharge 1.6-fold (20% O2) or 2.6-fold (300 microM cyanide), respectively, in association with membrane depolarization and a significant fall in membrane resistance. The membrane responses to hypoxia and cyanide were observed in the presence of tetrodotoxin (TTX) at a concentration (10 microM) which eliminated spontaneous spikes or spikes evoked by intracellular depolarization. When recorded at a holding potential of -70 mV by single-electrode voltage clamp, hypoxia or cyanide (300 microM) elicited inward currents of 0.44 +/- 0.06 and 0.58 +/- 0.08 nA, respectively, which are attenuated by reducing the concentration of extracellular Ca2+ ions, and abolished by 2 mM CoCl2 and 100 microM NiCl2, but not affected by 50 microM CdCl2, replacement of 83% extracellular Na+, or adenosine deaminase (2U ml-1). We conclude that hypoxia and cyanide directly excite RVL pacemaker neurones in vitro by a common mechanism: activation of Ca2+ channel conductance. Images Figure 5 PMID:8046626

Sun, M K; Reis, D J

1994-01-01

310

The emergence of subcellular pacemaker sites for calcium waves and oscillations  

PubMed Central

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

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

2013-01-01

311

Circadian pacemaker coupling by multi-peptidergic neurons in the cockroach Leucophaea maderae.  

PubMed

Lesion and transplantation studies in the cockroach, Leucophaea maderae, have located its bilaterally symmetric circadian pacemakers necessary for driving circadian locomotor activity rhythms to the accessory medulla of the optic lobes. The accessory medulla comprises a network of peptidergic neurons, including pigment-dispersing factor (PDF)-expressing presumptive circadian pacemaker cells. At least three of the PDF-expressing neurons directly connect the two accessory medullae, apparently as a circadian coupling pathway. Here, the PDF-expressing circadian coupling pathways were examined for peptide colocalization by tracer experiments and double-label immunohistochemistry with antisera against PDF, FMRFamide, and Asn(13)-orcokinin. A fourth group of contralaterally projecting medulla neurons was identified, additional to the three known groups. Group one of the contralaterally projecting medulla neurons contained up to four PDF-expressing cells. Of these, three medium-sized PDF-immunoreactive neurons coexpressed FMRFamide and Asn(13)-orcokinin immunoreactivity. However, the contralaterally projecting largest PDF neuron showed no further peptide colocalization, as was also the case for the other large PDF-expressing medulla cells, allowing the easy identification of this cell group. Although two-thirds of all PDF-expressing medulla neurons coexpressed FMRFamide and orcokinin immunoreactivity in their somata, colocalization of PDF and FMRFamide immunoreactivity was observed in only a few termination sites. Colocalization of PDF and orcokinin immunoreactivity was never observed in any of the terminals or optic commissures. We suggest that circadian pacemaker cells employ axonal peptide sorting to phase-control physiological processes at specific times of the day. PMID:21229364

Soehler, Sandra; Stengl, Monika; Reischig, Thomas

2011-03-01

312

Cardiac Risk Assessment  

MedlinePLUS

... helpful? Formal name: Cardiac Risk Assessment Related tests: Lipid Profile , VLDL Cholesterol , hs-CRP , Lp(a) Overview | ... on Coronary artery disease: Tests and diagnosis .) The lipid profile is the most important blood test for ...

313

Missed cardiac tamponade  

PubMed Central

Cardiac tamponade can have an insidious onset, becoming life threatening when an adequate cardiac output can no longer be maintained. This case provides an example of a presentation where all the classic signs were present but unfortunately they were missed, in this way providing good revision of what these signs are. It gives some anaesthetic and procedure based perspectives for this rare presentation. It is noteworthy for the speed at which symptoms and signs resolved after the tamponade was relieved. PMID:22679253

Thomson-Moore, Alexandra Louise

2011-01-01

314

Cardiac catheterization laboratory management: the fundamentals.  

PubMed

Increasingly, imaging administrators are gaining oversight for the cardiac cath lab as part of imaging services. Significant daily challenges include physician and staff demands, as well as patients who in many cases require higher acuity care. Along with strategic program driven responsibilities, the management role is complex. Critical elements that are the major impacts on cath lab management, as well as the overall success of a cardiac and vascular program, include program quality, patient safety, operational efficiency including inventory management, and customer service. It is critically important to have a well-qualified cath lab manager who acts as a leader by example, a mentor and motivator of the team, and an expert in the organization's processes and procedures. Such qualities will result in a streamlined cath lab with outstanding results. PMID:22720540

Newell, Amy

2012-01-01

315

Spatiotemporal Regulation of an Hcn4 Enhancer Defines a Role for Mef2c and HDACs in Cardiac Electrical Patterning  

PubMed Central

Regional differences in cardiomyocyte automaticity permit the sinoatrial node (SAN) to function as the leading cardiac pacemaker and the atrioventricular (AV) junction as a subsidiary pacemaker. The regulatory mechanisms controlling the distribution of automaticity within the heart are not understood. To understand regional variation in cardiac automaticity, we carried out an in vivo analysis of cis-regulatory elements that control expression of the hyperpolarization-activated cyclic-nucleotide gated ion channel 4 (Hcn4). Using transgenic mice, we found that spatial and temporal patterning of Hcn4 expression in the AV conduction system required cis-regulatory elements with multiple conserved fragments. One highly conserved region, which contained a myocyte enhancer factor 2C (Mef2C) binding site previously described in vitro, induced reporter expression specifically in the embryonic non-chamber myocardium and the postnatal AV bundle in a Mef2c-dependent manner in vivo. Inhibition of histone deacetylase (HDAC) activity in cultured transgenic embryos showed expansion of reporter activity to working myocardium. In adult animals, hypertrophy induced by transverse aortic constriction, which causes translocation of HDACs out of the nucleus, resulted in ectopic activation of the Hcn4 enhancer in working myocardium, recapitulating pathological electrical remodeling. These findings reveal mechanisms that control the distribution of automaticity among cardiomyocytes during development and in response to stress. PMID:23085412

Vedantham, Vasanth; Evangelista, Melissa; Huang, Yu; Srivastava, Deepak

2012-01-01

316

Simple, rapid /sup 125/I-labeled cyclosporine double antibody/polyethylene glycol radioimmunoassay used in a pediatric cardiac transplant program  

SciTech Connect

We modified the Sandoz cyclosporine radioimmunoassay because of our need for frequent clinical monitoring of cyclosporine drug levels in allo- and xenograft pediatric cardiac transplant patients. With application of a commercially available (/sup 125/I)cyclosporine label in place of (/sup 3/H)cyclosporine and a second antibody/polyethylene glycol (PEG) method of separation in place of charcoal separation, we simplified and enhanced the speed and precision of assay performance. Studies of 140 whole blood samples comparing this new method to the (/sup 3/H)cyclosporine radioimmunoassay (RIA) method of Berk and colleagues yielded a coefficient of correlation of 0.96 (p less than 0.00001) with means of 626 and 667 ng/ml for (/sup 3/H)RIA and (/sup 125/I)RIA, respectively, and a regression equation of y = 28 + 1.02x. The major advantages are that total assay time is reduced to approximately 1 h; (/sup 125/I)cyclosporine label is used, avoiding the problems associated with liquid scintillation counting; and precision is enhanced by separating bound and free fractions with second antibody/PEG. These modifications should provide for greater ease of assay performance and improved clinical utility of cyclosporine monitoring not only in the pediatric but also in the adult transplant patient.

Berk, L.S.; Webb, G.; Imperio, N.C.; Nehlsen-Cannarella, S.L.; Eby, W.C.

1986-01-01

317

The "automatic mode switch" function in successive generations of minute ventilation sensing dual chamber rate responsive pacemakers.  

PubMed

Automatic mode switch (AMS) from DDDR to VVIR pacing is a new algorithm, in response to paroxysmal atrial tachyarrhythmias. With the 5603 Programmer, the AMS in the Meta DDDR 1250 and 1250H (Telectronics Pacings Systems, Inc.) operates when VA is shorter than the adaptable PVARP. With the 9600 Programmer, an atrial protection interval can be defined after the PVARP. The latest generation, Meta DDDR 1254, initiates AMS when 5 or 11 heart cycles are > 150, 175, or 200 beats/min. From 1990 to 1993, 61 patients, mean age 61 years, received a Meta DDDR: in 24 a 1250, in 12 a 1250H and in the remaining 25 a 1254 model. Indication for pacing was heart block in 39, sick sinus syndrome in 15, the combination in 6, and hypertrophic obstructive cardiomyopathy in 1. Paroxysmal atrial tachyarrhythmias were present in 43. All patients had routine pacemaker surveillance, including 52 Holter recordings. In 32 patients, periods of atrial tachyarrhythmias were observed, with proper AMS to VVIR, except during short periods of 2:1 block for atrial flutter in 4. In two others, undersensing of the atrial arrhythmia disturbed correct AMS. With the 1250 and 1250H model, AMS was observed on several occasions during sinus rate accelerations in ten patients. This was never seen with the 1254 devices. Final programmation was VVIR in 2 (chronic atrial fibrillation), AAI in 1 (fracture of the ventricular lead), VDDR in 1 (atrial pacing during atrial fibrillation), DDD in 5, and DDDR in 53, 48 of whom had AMS programmed on.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7845791

Provenier, F; Jordaens, L; Verstraeten, T; Clement, D L

1994-11-01

318

Platelet aggregating activity in serum from patients with HLA-B27 associated rheumatic and cardiac disorders: a possible link to the proliferative vascular changes.  

PubMed Central

OBJECTIVE--To search for possible serum factors (immunochemical abnormalities) that reflect HLA-B27 associated inflammatory process with the proliferative endarteritis, which is an important cause of severe bradycardia and aortic valve regurgitation. PATIENTS AND METHODS--Seventy four men with pacemakers were studied: 24 were HLA-B27 positive and had associated rheumatic and cardiac disorders, 13 were B27 positive but had no clinical or radiographic signs of a related rheumatic condition, and 37 were B27 negative controls. Randomly obtained serum samples were examined for a series of serum factors. RESULTS--Thirteen (57%) of the 23 patients with HLA-B27 and associated rheumatic and cardiac conditions had platelet aggregating activity in their serum. No such activity was found in sera from patients in the other groups. None the less, immunochemical abnormalities were common among patients of all groups; 30 (41%) had antinuclear antibodies or rheumatoid factor or both. CONCLUSION--The platelet aggregating activity found in patients with HLA-B27 and associated rheumatic and cardiac conditions may reflect serum factors that increase the stickiness of platelets and increase their adhesion to the vessel wall. This suggests a link via release of platelet derived growth factor(s) with the characteristic histopathological feature of proliferative endarteritis. Immunochemical abnormalities were common in serum from all men with pacemakers. PMID:2029440

Bergfeldt, L; Edhag, O; Holm, G; Norberg, R

1991-01-01

319

Restricted feeding uncouples circadian oscillators in peripheral tissues from the central pacemaker in the suprachiasmatic nucleus  

PubMed Central

In mammals, circadian oscillators exist not only in the suprachiasmatic nucleus, which harbors the central pacemaker, but also in most peripheral tissues. It is believed that the SCN clock entrains the phase of peripheral clocks via chemical cues, such as rhythmically secreted hormones. Here we show that temporal feeding restriction under light–dark or dark–dark conditions can change the phase of circadian gene expression in peripheral cell types by up to 12 h while leaving the phase of cyclic gene expression in the SCN unaffected. Hence, changes in metabolism can lead to an uncoupling of peripheral oscillators from the central pacemaker. Sudden large changes in feeding time, similar to abrupt changes in the photoperiod, reset the phase of rhythmic gene expression gradually and are thus likely to act through a clock-dependent mechanism. Food-induced phase resetting proceeds faster in liver than in kidney, heart, or pancreas, but after 1 wk of daytime feeding, the phases of circadian gene expression are similar in all examined peripheral tissues. PMID:11114885

Damiola, Francesca; Le Minh, Nguyet; Preitner, Nicolas; Kornmann, Benoît; Fleury-Olela, Fabienne; Schibler, Ueli

2000-01-01

320

Drosophila TRPA1 functions in temperature control of circadian rhythm in pacemaker neurons  

PubMed Central

Most animals from flies to humans count on circadian clocks to synchronize their physiology and behaviors. Daily light cycles are well-known environmental cues for setting circadian rhythms. Warmer and cooler temperatures that mimic day and night are also effective in entraining circadian activity in most animals. Even vertebrate organisms can be induced to show circadian responses through exposure to temperature cycles. In poikilothermic animals such as Drosophila, temperature differences of only 2–3°C are sufficient to synchronize locomotor rhythms. However, the molecular sensors that participate in temperature regulation of circadian activity in fruit flies or other animals are enigmatic. It is also unclear whether such detectors are limited to the periphery or may be in the central brain. Here, we showed that Drosophila TRPA1 (Transient Receptor Potential Cation Channel A1) was necessary for normal activity patterns during temperature cycles. The trpA1 gene was expressed in a subset of pacemaker neurons in the central brain. In response to temperature entrainment, loss of trpA1 impaired activity, and altered expression of the circadian clock protein Period (Per) in a subset of pacemaker neurons. These findings underscore a role for a thermoTRP in temperature regulation that extends beyond avoidance of noxious or suboptimal temperatures. PMID:23595730

Lee, Youngseok; Montell, Craig

2013-01-01

321

Cardiac radiology: centenary review.  

PubMed

During the past century, cardiac imaging technologies have revolutionized the diagnosis and treatment of acquired and congenital heart disease. Many important contributions to the field of cardiac imaging were initially reported in Radiology. The field developed from the early stages of cardiac imaging, including the use of coronary x-ray angiography and roentgen kymography, to nowadays the widely used echocardiographic, nuclear medicine, cardiac computed tomographic (CT), and magnetic resonance (MR) applications. It is surprising how many of these techniques were not recognized for their potential during their early inception. Some techniques were described in the literature but required many years to enter the clinical arena and presently continue to expand in terms of clinical application. The application of various CT and MR contrast agents for the diagnosis of myocardial ischemia is a case in point, as the utility of contrast agents continues to expand the noninvasive characterization of myocardium. The history of cardiac imaging has included a continuous process of advances in our understanding of the anatomy and physiology of the cardiovascular system, along with advances in imaging technology that continue to the present day. PMID:25340434

de Roos, Albert; Higgins, Charles B

2014-11-01

322

Efficacy of atrial antitachycardia pacing using the Medtronic AT500 pacemaker in patients with congenital heart disease  

Microsoft Academic Search

Patients with congenital heart disease are vulnerable to atrial tachyarrhythmias, especially after atrial surgeries. We evaluated the efficacy of atrial arrhythmia detection and antitachycardia pacing (ATP) using the Medtronic AT500 pacemaker in 28 patients with congenital heart disease (age 30 ± 18 years). Of 15 patients with atrial arrhythmias, 14 had atrial tachycardia events that were appropriately detected. ATP was

Elizabeth A. Stephenson; David Casavant; Joann Tuzi; Mark E. Alexander; Ian Law; Gerald Serwer; Margaret Strieper; Edward P. Walsh; Charles I. Berul

2003-01-01

323

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

SciTech Connect

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

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

1980-01-01

324

1. Preventing Accidental Changes of Pacemaker Controls Do not place the Model 5388 in any area where patients may  

E-print Network

5409 disposable pouch is an optional accessory available from Medtronic that can add additional REFERENCE TIPS FOR SAFE AND RELIABLE OPERATION The Medtronic 5388 Dual Chamber Temporary Pacemaker. Manufacturer Medtronic, Inc. 710 Medtronic Parkway Minneapolis, MN 55432-5604 USA Distributor Medtronic

Kay, Mark A.

325

IEEE SENSORS JOURNAL, VOL. 12, NO. 6, JUNE 2012 1817 Body Sensors Applied in Pacemakers: A Survey  

E-print Network

, biosensor, implantable sensor, pacemaker, physiological response, power consumption, reliability. I. INTRODUCTION CARDIOVASCULAR diseases are major causes of mor- bidity and mortality in the developed countries muscles, to regulate the beating of the heart. Its primary purpose is to treat bradycardia due to sinus

Wu, Mingshen

326

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

PubMed

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 Ca(2+) oscillations in ICC appear to produce the slow waves by activating pacemaker currents, currently thought to be carried by the Ca(2+)-activated Cl(-) channel anoctamin 1 (Ano1). In this article we present a novel model of small intestinal ICC pacemaker activity that incorporates store-operated Ca(2+) 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 Ca(2+) channel but suggest that small cyclical depolarizations may still occur in ICC in Ano1 knockout mice. The results predict that voltage-dependent Ca(2+) 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

Lees-Green, Rachel; Gibbons, Simon J; Farrugia, Gianrico; Sneyd, James; Cheng, Leo K

2014-04-15

327

Campylobacter fetus infection presenting with bacteremia and cellulitis in a 72-year-old man with an implanted pacemaker: a case report  

PubMed Central

Introduction Campylobacter is an important causative agent of intestinal infections in humans. Bacteremia is detected in less than 1% of patients, mainly in immunocompromised patients and in extreme age groups. Cellulitis is a relatively common manifestation of Campylobacter infection, but concomitant bacteremia is a rare event. Infections of the pacemaker area are caused primarily by staphylococci, followed by fungi, streptococci and Gram-negative rods. To the best of our knowledge, this is the first case report of pacemaker pocket infection and bacteremia caused by Campylobacter fetus. Case presentation A 72-year-old Croatian Caucasian man with myelodysplasia, impaired fasting glucose levels and a recently implanted permanent pacemaker was admitted to hospital after six days of fever, development of red swelling of the pacemaker pocket area and worsening of his general condition. No antibiotic therapy was introduced in the outpatient setting. He denied any recent gastrointestinal disturbances. With the exception of an elevated leukocyte count, erythrocyte sedimentation rate, and C-reactive protein and blood glucose levels, other laboratory findings were normal. Treatment with vancomycin plus netilmicin was introduced, and a surgical incision with drainage of the pacemaker pocket was performed. The entire pacemaker system was removed and a new one re-implanted after 14 days of antibiotic therapy. Transesophageal echocardiography showed no pathological findings. Three subsequent blood cultures obtained on admission as well as swab culture of the incised pacemaker area revealed Campylobacter fetus; stool and pacemaker lead cultures were negative. According to the microbiological results, antibiotic therapy was changed to ciprofloxacin plus netilmicin. A clinical examination and the results of a laboratory analysis performed after two weeks of therapy were within normal limits. Conclusion Myelodysplasia, impaired fasting glucose levels and older age could be contributing factors for the development of bacteremic Campylobacter fetus cellulitis. Emergent surgical and antibiotic treatment are mandatory and provide the optimal outcome for such types of pacemaker pocket infection. PMID:23198848

2012-01-01

328

A Model of Cellular Cardiac-Neural Coupling That Captures the Sympathetic Control of Sinoatrial Node Excitability in Normotensive and Hypertensive Rats  

PubMed Central

Hypertension is associated with sympathetic hyperactivity. To represent this neural-myocyte coupling, and to elucidate the mechanisms underlying sympathetic control of the cardiac pacemaker, we developed a new (to our knowledge) cellular mathematical model that incorporates signaling information from cell-to-cell communications between the sympathetic varicosity and sinoatrial node (SAN) in both normotensive (WKY) and hypertensive (SHR) rats. Features of the model include 1), a description of pacemaker activity with specific ion-channel functions and Ca2+ handling elements; 2), dynamic ?-adrenergic modulation of the excitation of the SAN; 3), representation of ionic activity of sympathetic varicosity with NE release dynamics; and 4), coupling of the varicosity model to the SAN model to simulate presynaptic transmitter release driving postsynaptic excitability. This framework captures neural-myocyte coupling and the modulation of pacemaking by nitric oxide and cyclic GMP. It also reproduces the chronotropic response to brief sympathetic stimulations. Finally, the SHR model quantitatively suggests that the impairment of cyclic GMP regulation at both sides of the sympathetic cleft is crucial for development of the autonomic phenotype observed in hypertension. PMID:21806927

Tao, T.; Paterson, David J.; Smith, Nicolas P.

2011-01-01

329

Cardiac transthyretin amyloidosis.  

PubMed

Cardiac amyloidosis of transthyretin fibril protein (ATTR) type is an infiltrative cardiomyopathy characterised by ventricular wall thickening and diastolic heart failure. Increased access to cardiovascular magnetic resonance imaging has led to a marked increase in referrals to our centre of Caucasian patients with wild-type ATTR (senile systemic) amyloidosis and Afro-Caribbean patients with the hereditary ATTR V122I type. Both subtypes present predominantly as isolated cardiomyopathy. The differential diagnosis includes cardiac amyloid light-chain (AL) amyloidosis, which has a poorer prognosis and can be amenable to chemotherapy. We review here the clinical features of cardiac ATTR amyloidosis and describe the diagnostic tests to determine ATTR type. Correct diagnosis is ever more crucial given that several novel therapies for ATTR amyloidosis are on the near horizon. PMID:22888163

Dungu, Jason N; Anderson, Lisa J; Whelan, Carol J; Hawkins, Philip N

2012-11-01

330

What are we measuring? Considerations on subjective ratings of perceived exertion in obese patients for exercise prescription in cardiac rehabilitation programs  

Microsoft Academic Search

We sought to describe the differences in exercise prescription in obese subjects using attained METs as compared to the subjective perception of the effort using the Borg scale ratings of perceived exertion (Borg RPE). We studied 552 obese patients who underwent an exercise stress test in the setting of a rehabilitation program. Exercise was prescribed at 70% of peak attained

Luca Alessandro Gondoni; Ferruccio Nibbio; Giulia Caetani; Giovanni Augello; Anna Maria Titon

2010-01-01

331

Cardiac Tumors: A Brief Commentary  

PubMed Central

Patients with cardiac tumors may present with cardiovascular related or constitutional symptoms, but more often than not a cardiac mass is discovered incidentally during an imaging examination performed for an unrelated indication. Cardiac myxoma is generally considered to be a surgical emergency. Echocardiography, including the transesophageal approach, is the most important means of diagnosis; computed tomography and magnetic resonance imaging. The clinical presentation has changed, and the management of cardiac myxoma now needs to be reviewed.

Roever, Leonardo; Casella-Filho, Antonio; Dourado, Paulo Magno Martins; Resende, Elmiro Santos; Chagas, Antônio Carlos Palandri

2014-01-01

332

Emergency Cardiac Care: An Update  

PubMed Central

The authors review the new guidelines for basic life support and advanced cardiac life support and the recommended changes to the standards. The changes recommended for basic life support will simplify the psychomotor skills required. The recommended changes to the guidelines for advanced cardiac life support, which include discontinuing the use of isoproterenol and limiting the use of sodium bicarbonate in cardiac arrest, are likely to improve survival rates. Controversies in the management of cardiac arrest are also discussed. PMID:21253157

Swanson, Richard W.

1988-01-01

333

From beat rate variability in induced pluripotent stem cell-derived pacemaker cells to heart rate variability in human subjects  

PubMed Central

Background We previously reported that induced Pluripotent Stem Cell-derived cardiomyocytes (iPSC-CM) manifest beat rate variability (BRV) resembling heart rate variability (HRV) in human sinoatrial node (SAN). We now hypothesized the BRV-HRV continuum originates in pacemaker cells. Objective To investigate whether cellular BRV is a source of HRV dynamics, we hypothesized three-levels of interaction among different cardiomyocyte entities: (1) single pacemaker cells, (2) networks of electrically coupled pacemaker cells and (3) in situ SAN. Methods We measured BRV/HRV properties in single pacemaker cells, iPSC-derived contracting embryoid bodies (EBs) and electrocardiograms from the same individual. Results Pronounced BRV/HRV were present at all three levels. Coefficient of variance (COV) of inter-beat intervals (IBI) and Poincaré plot SD1 and SD2 in single cells were 20x > EBs (P<0.05) and in situ heart (the latter two were similar, P>0.05). We also compared BRV magnitude among single cells, small (~5-10 cells) and larger EBs (>10 cells): BRV indices progressively increased (P<0.05) as cell number decreased. Disrupting intracellular Ca2+ handling markedly augmented BRV magnitude, revealing a unique bi-modal firing pattern, suggesting intracellular mechanisms contribute to BRV/HRV and the fractal behavior of heart rhythm. Conclusions The decreased BRV magnitude in transitioning from single cell to EB suggests HRV of hearts in situ originates from summation and integration of multiple cell-based oscillators. Hence, complex interactions among multiple pacemaker cells and intracellular Ca2+ handling determine HRV in humans and isolated cardiomyocyte networks. PMID:25052725

Barad, Lili; Novak, Atara; Ben-Ari, Erez; Lorber, Avraham; Itskovitz-Eldor, Joseph; Rosen, Michael R; Weissman, Amir; Binah, Ofer

2014-01-01

334

Macrophage diversity in cardiac inflammation: a review  

PubMed Central

Cardiac inflammatory disease represents a significant public health burden, and interesting questions of immunopathologic science and clinical inquiry. Novel insights into the diverse programming and functions within the macrophage lineages in recent years have yielded a view of these cells as dynamic effectors and regulators of immunity, host defense, and inflammatory disease. In this review, we examine and discuss recent investigations into the complex participation of mononuclear phagocytic cells in the pathology of animal models of myocarditis. PMID:21820754

Barin, Jobert G.; Rose, Noel R.; ?iháková, Daniela

2014-01-01

335

The contribution of changes in diet, exercise, and stress management to changes in coronary risk in women and men in the Multisite Cardiac Lifestyle Intervention Program  

Microsoft Academic Search

Background: The relative contribution of health behaviors to coronary risk factors in multicomponent secondary coronary heart disease\\u000a (CHD) prevention programs is largely unknown.Purpose: Our purpose is to evaluate the additive and interactive effects of 3-month changes in health behaviors (dietary fat intake,\\u000a exercise, and stress management) on 3-month changes in coronary risk and psychosocial factors among 869 nonsmoking CHD patients

Jennifer J. Daubenmier; Gerdi Weidner; Michael D. Sumner; Nancy Mendell; Terri Merritt-Worden; Joli Studley; Dean Ornish

2007-01-01

336

End-tidal CO2 measurement in the detection of esophageal intubation during cardiac arrest.  

PubMed

Measurement of end-tidal carbon dioxide (ETCO2) has been used to detect accidental esophageal tube placement in noncardiac arrest situations. The purpose of our study was to determine whether ETCO2 measurement could distinguish tracheal from esophageal tube placement during closed-chest massage (CCM). Twelve large dogs were anesthetized, and endotracheal tubes were placed in both the trachea and the esophagus. Placement was verified by fiberoptic endoscopy. Ventricular fibrillation was induced by a 60-Hz discharge through a right ventricular pacemaker. After four minutes of cardiac arrest, CCM was initiated and continued for 20 minutes. The dogs were divided into two groups: Group A was ventilated through the tracheal tube, and group B was ventilated through the esophageal tube. Unused tubes were removed. ETCO2 was recorded continuously beginning two minutes before arrest until the end of the experiment. There were no significant between-group differences in mean arterial pressure, weight, blood loss, IV fluid volume administered, or prearrest arterial blood gases. ETCO2 differed significantly between the two groups throughout CCM (P = .001). In group A, ETCO2 ranged from 13 to 34 mm Hg (median, 20 mm Hg). In group B, ETCO2 ranged from 2 to 11 mm Hg (median, 3 mm Hg). In this experimental model, measurement of ETCO2 reliably distinguished esophageal from tracheal intubation during cardiac arrest and CCM. If confirmed in human beings, this may prove to be a quick, reliable method of detecting esophageal intubation during cardiac arrest. PMID:2115315

Sayah, A J; Peacock, W F; Overton, D T

1990-08-01

337

Is there an association between Fahr's disease and cardiac conduction system disease?: A case report  

PubMed Central

BACKGROUND: Fahr's disease is a rare neurodegenerative disorder of unknown cause characterized by idiopathic basal ganglia calcification that is associated with neuropsychiatric and cognitive impairment. No case of Fahr's disease with associated cardiac conduction disease has been described in the literature to date. The objective of this case report was to describe a young female with various cardiac conduction system abnormalities and bilateral basal ganglia calcification suggestive of Fahr's disease. CASE REPORT: A 19-year-old female was transferred to our hospital for a pacemaker insertion. Her past medical history included cognitive impairment and asymptomatic congenital complete heart block since birth. Her manifestations included cognitive impairment, tremors, rigidity, ataxia, bilateral basal ganglia calcification without clinical manifestations of mitochondrial cytopathy. She also had right bundle branch block, left anterior fascicular block, intermittent complete heart block, atrial arrhythmias with advanced atrioventricular blocks and ventricular asystole manifested by Stokes-Adams seizures, which was diagnosed as epilepsy. CONCLUSIONS: According to our knowledge, this was the first case report of a su spected association between Fahr's disease and isolated cardiac conduction system disease. In addition, this case illustrated that in patients with heart blocks and seizures, a diagnosis of epilepsy needs to be made with caution and such patients need further evaluations by a cardiologist or electrophysiologist to consider pacing and prevent future catastrophic events. PMID:23248663

Panduranga, Prashanth; Sulaiman, Kadhim

2012-01-01

338

Cardiac memory during rather than after termination of left bundle branch block.  

PubMed

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

Littmann, Laszlo; Proctor, Patrick A; Givens, Priscilla M

2014-01-01

339

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

PubMed Central

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

Occhetta, Eraldo; Bortnik, Miriam; Marino, Paolo

2011-01-01

340

Usefulness of hemodynamic sensors for physiologic cardiac pacing in heart failure patients.  

PubMed

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

Occhetta, Eraldo; Bortnik, Miriam; Marino, Paolo

2011-01-01

341

Cardiac Health Diagnosis Using Higher Order Spectra and Support Vector Machine  

PubMed Central

The Electrocardiogram (ECG) is an important bio-signal representing the sum total of millions of cardiac cell depolarization potentials. It contains important insight into the state of health and nature of the disease afflicting the heart. Heart rate variability (HRV) refers to the regulation of the sinoatrial node, the natural pacemaker of the heart by the sympathetic and parasympathetic branches of the autonomic nervous system. The HRV signal can be used as a base signal to observe the heart's functioning. These signals are non-linear and non-stationary in nature. So, higher order spectral (HOS) analysis, which is more suitable for non-linear systems and is robust to noise, was used. An automated intelligent system for the identification of cardiac health is very useful in healthcare technology. In this work, we have extracted seven features from the heart rate signals using HOS and fed them to a support vector machine (SVM) for classification. Our performance evaluation protocol uses 330 subjects consisting of five different kinds of cardiac disease conditions. We demonstrate a sensitivity of 90% for the classifier with a specificity of 87.93%. Our system is ready to run on larger data sets. PMID:19603098

Chua, Chua Kuang; Chandran, Vinod; Acharya, Rajendra U; Min, Lim Choo

2009-01-01

342

Attitudes of Implanting Physicians about Cardiac Rhythm Management Devices and Their Features  

PubMed Central

Modern cardiac rhythm management systems have become increasingly complex. The decision on which specific system to implant in a given patient often rests with the implanting physician. We conducted a multiple-choice survey to assess the opinions and preferences of cardiologists and electrophysiologists who implant and follow cardiac rhythm management systems. Reliability and battery longevity were viewed as the most important characteristics in device selection. Patient characteristics which most affected device choice were pacing indication and life expectancy. Remote technology was used in 47% of pacemaker patients, 64% of ICD patients, and 65% of CRT-D patients, with wireless (radiofrequency) remote patient monitoring associated with higher patient compliance rates (74% versus 64%, resp.). Wireless remote patient management with alerts for atrial tachyarrhythmias was felt to be important by 76% of respondents. When choosing an MR-conditional device, physicians deemed patients with prior orthopedic problems, a history of cancer, or neurological disorders to be more likely to require a future MRI. Device longevity and reliability remain the most important factors which influence device selection. Wireless remote patient monitoring with alerts is considered increasingly important when choosing a specific cardiac rhythm management system to implant. PMID:24490084

Elmouchi, Darryl A.; Chalfoun, Nagib; Gauri, Andre

2013-01-01

343

Cardioprotective effects of the ?f current inhibition by ivabradine during cardiac dysfunction.  

PubMed

Heart rate is a fundamental determinant of cardiac function. Normally, the increase in heart rate is accompanied by increased cardiac function. But under pathological conditions such as myocardial infarction and heart failure, accelerated heart rate may become detrimental as it decreases the diastolic time for left ventricular filling and myocardial perfusion but increases left ventricular myocardial oxygen demand. Therefore, heart rate reduction is an appropriate strategy to protect cardiac function. Heart rate reduction can be achieved by different bradycardic drugs, including beta-blockers, calcium channel blockers and selective f-channel inhibitors. By competing with norepinephrine and epinephrine for binding sites, beta-blockers block beta-adrenoceptor-mediated responses to sympathetic stimulation. This induces heart rate reduction and negative inotropy. Calcium channel blockers block calcium influx via specific calcium channels, causing vasodilation and decreases in heart rate, conduction velocity within the heart and myocardial force generation. The selective f-channel inhibitor, ivabradine, inhibits If currents that play an exclusive role in pacemaking and thereby slows heart rate without altering myocardial inotropy. Since these drugs differ in their mechanisms of action, they may cause different beneficial and side effects and thus different outcome according to pathological states. After briefly describing the mechanisms involved in beta-blockers and calcium channel blockers, this review focuses on the bradycardic property of ivabradine and its pleiotropic actions. PMID:24831809

Su, Jin B

2014-01-01

344

Attitudes of Implanting Physicians about Cardiac Rhythm Management Devices and Their Features.  

PubMed

Modern cardiac rhythm management systems have become increasingly complex. The decision on which specific system to implant in a given patient often rests with the implanting physician. We conducted a multiple-choice survey to assess the opinions and preferences of cardiologists and electrophysiologists who implant and follow cardiac rhythm management systems. Reliability and battery longevity were viewed as the most important characteristics in device selection. Patient characteristics which most affected device choice were pacing indication and life expectancy. Remote technology was used in 47% of pacemaker patients, 64% of ICD patients, and 65% of CRT-D patients, with wireless (radiofrequency) remote patient monitoring associated with higher patient compliance rates (74% versus 64%, resp.). Wireless remote patient management with alerts for atrial tachyarrhythmias was felt to be important by 76% of respondents. When choosing an MR-conditional device, physicians deemed patients with prior orthopedic problems, a history of cancer, or neurological disorders to be more likely to require a future MRI. Device longevity and reliability remain the most important factors which influence device selection. Wireless remote patient monitoring with alerts is considered increasingly important when choosing a specific cardiac rhythm management system to implant. PMID:24490084

Elmouchi, Darryl A; Chalfoun, Nagib; Gauri, Andre

2013-01-01

345

Melatonin and cardiac pathophysiology  

Microsoft Academic Search

Melatonin, an indole produced in several organs but most notably in the pineal gland, has a variety of effects that influence cardiac pathophysiology. Herein, we summarize the findings that illustrate the ability of melatonin to attenuate the severity of hypertension, limit myocardial damage, improve the function of the ischemic-reperfused heart, protect the heart from the toxicity of anthracycline drugs and

Russel J. Reiter; Dun X. Tan

346

Fetal cardiac anomalies  

Microsoft Academic Search

Fetal cardiac anomalies are increasingly identified during regular obstetric scanning. About 21000 pregnancies will have an abnormality of the four chamber view and a further 11000 will have an abnormality of the great arteries. These cases can then be referred to the specialist in fetal cardiology for further evaluation and counselling. There is a higher rate of chromosomal and other

Lindsey D. Allan

1996-01-01

347

Cardiac fibroma in adults.  

PubMed

We present the case of a 61-year-old woman with nonspecific symptoms who on investigation and treatment had a fibroma of the right ventricular free wall. She underwent surgical resection of the mass and is doing well. The literature pertaining to cardiac fibromas in adults is reviewed and discussed. PMID:20934889

Nwachukwu, Harriet; Li, Alice; Nair, Vidhya; Nguyen, Elsie; David, Tirone E; Butany, Jagdish

2011-01-01

348

Cardiac function monitoring system  

Microsoft Academic Search

An IBM-PC controlled system has been developed to evaluate the cardiac function in the catheterization room. The system uses a multielectrode impedancimetric catheter to compute the instantaneous left intraventricular heart volume, through specially developed algorithms and calibration procedures, and a catheter tip micromanometer to measure the instantaneous left intraventricular pressure. With these two variables, and after a preload maneuver, the

J. C. Spinelli; M. C. Herrera

1988-01-01

349

The noise sampling period: a new cause of apparent sensing malfunction of demand pacemakers.  

PubMed

Two patients with Omni-Stanicor pulse generators presented an apparent sensing problem characterized by intermittent reversion to fixed-rate pacing only during atrial fibrillation with a very rapid ventricular rate. Every fixed-rate cycle contained two unsensed beats. The first unsensed beat fell in the noise sampling period (the last 1/6 of the pacemaker refractory period) and, therefore, disabled the demand function of the pulse generator for a single timing cycle. The presence of two consecutively unsensed beats within one timing cycle (automatic or escape interval) during tachycardia suggests normal function of the noise sampling period of this particular pulse generator, rather than a true sensing problem. The diagnosis becomes evident if the sensing problem disappears when abbreviation of the refractory period occurs by reprogramming the pulse generator at a higher rate. PMID:83638

Falkoff, M; Ong, L S; Heinle, R A; Barold, S S

1978-04-01

350

Mop3 Is an Essential Component of the Master Circadian Pacemaker in Mammals  

PubMed Central

Summary Circadian oscillations in mammalian physiology and behavior are regulated by an endogenous biological clock. Here we show that loss of the PAS protein MOP3 (also known as BMAL1) in mice results in immediate and complete loss of circadian rhythmicity in constant darkness. Additionally, locomotor activity in light–dark (LD) cycles is impaired and activity levels are reduced in Mop3?/? mice. Analysis of Period gene expression in the suprachiasmatic nucleus (SCN) indicates that these behavioral phenotypes arise from loss of circadian function at the molecular level. These results provide genetic evidence that MOP3 is the bona fide heterodimeric partner of mCLOCK. Furthermore, these data demonstrate that MOP3 is a non-redundant and essential component of the circadian pacemaker in mammals. PMID:11163178

Bunger, Maureen K.; Wilsbacher, Lisa D.; Moran, Susan M.; Clendenin, Cynthia; Radcliffe, Laurel A.; Hogenesch, John B.; Simon, M. Celeste; Takahashi, Joseph S.; Bradfield, Christopher A.

2013-01-01

351

Ethical Issues in Cardiac Surgery  

PubMed Central

While ethical behavior has always been part of cardiac surgical practice, ethical deliberation has only recently become an important component of cardiac surgical practice. Issues such as informed consent, conflict of interest, and professional self-regulation, among many others, have increasingly attracted the attention of cardiac surgeons. This review covers several broad topics of interest to cardiac surgeons and cardiologists, and treats several other topics more briefly. There is much uncertainty about what the future holds for cardiac surgical practice, research, and culture, and we discuss the background of ethical issues to serve as a platform for envisioning what is to come. PMID:22642634

Kavarana, Minoo N.; Sade, Robert M.

2012-01-01

352

Multiple mechanisms of spiral wave breakup in a model of cardiac electrical activity  

NASA Astrophysics Data System (ADS)

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.

Fenton, Flavio H.; Cherry, Elizabeth M.; Hastings, Harold M.; Evans, Steven J.

2002-09-01

353

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

PubMed Central

The rhythmic motor pathway activation by pacemaker neurons or circuits in the brain has been proposed as the mechanism for the timing of motor coordination, and the abnormal potentiation of this mechanism may lead to a pathological tremor. Here, we show that the potentiation of CaV3.1 T-type Ca2+ channels in the inferior olive contributes to the onset of the tremor in a pharmacological model of essential tremor. After administration of harmaline, 4- to 10-Hz synchronous neuronal activities arose from the IO and then propagated to cerebellar motor circuits in wild-type mice, but those rhythmic activities were absent in mice lacking CaV3.1 gene. Intracellular recordings in brain-stem slices revealed that the CaV3.1-deficient inferior olive neurons lacked the subthreshold oscillation of membrane potentials and failed to trigger 4- to 10-Hz rhythmic burst discharges in the presence of harmaline. In addition, the selective knockdown of CaV3.1 gene in the inferior olive by shRNA efficiently suppressed the harmaline-induced tremor in wild-type mice. A mathematical model constructed based on data obtained from patch-clamping experiments indicated that harmaline could efficiently potentiate CaV3.1 channels by changing voltage-dependent responsiveness in the hyperpolarizing direction. Thus, CaV3.1 is a molecular pacemaker substrate for intrinsic neuronal oscillations of inferior olive neurons, and the potentiation of this mechanism can be considered as a pathological cause of essential tremor. PMID:20498062

Park, Young-Gyun; Park, Hye-Yeon; Lee, C. Justin; Choi, Soonwook; Jo, Seonmi; Choi, Hansol; Kim, Yang-Hann; Shin, Hee-Sup; Llinas, Rodolfo R.; Kim, Daesoo

2010-01-01

354

Inhibitory effects of sevoflurane on pacemaking activity of sinoatrial node cells in guinea-pig heart  

PubMed Central

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

Kojima, Akiko; Kitagawa, Hirotoshi; Omatsu-Kanbe, Mariko; Matsuura, Hiroshi; Nosaka, Shuichi

2012-01-01

355

Surgical management of cardiac implantable electronic device infections  

PubMed Central

Purpose The infection of cardiac implantable electronic devices (CIED) is a serious and potentially lethal complication. The population at risk is growing, as the device implantation is increasing especially in older patients with associated comorbid conditions. Our purpose was to present the management of this complicated surgical condition and to extract the relevant conclusions. Methods During a 3-year period 1,508 CIED were implanted in our hospital. We treated six cases of permanent pacemaker infection with localized pocket infection or endocarditis. In accordance to the recent AHA/ACC guidelines, complete device removal was decided in all cases. The devices were removed under general anaesthesia, with a midline sternotomy, under extracorporeal circulation on the beating heart. Epicardial permanent pacing electrodes were placed on the right atrium and ventricle before the end of the procedure. Results The postoperative course of all patients was uncomplicated and after a follow up period of five years no relapse of infection occurred. Conclusions Management protocols that include complete device removal are the only effective measure for the eradication of CIED infections. Although newer technologies have emerged and specialized techniques of percutaneous device removal have been developed, the surgical alternative to these methods can be a safe solution in cases of infected devices. PMID:24672692

Koutentakis, Michael; Siminelakis, Stavros; Korantzopoulos, Panagiotis; Petrou, Alexandra; Priavali, Eleftheria; Mpakas, Andreas; Gesouli, Eleftheria; Apostolakis, Eleftheria; Tsakiridis, Kosmas; Katsikogiannis, Nikolaos; Kougioumtzi, Ioanna; Machairiotis, Nikolaos; Tsiouda, Theodora; Zarogoulidis, Konstantinos

2014-01-01

356

HCN Channels—Modulators of Cardiac and Neuronal Excitability  

PubMed Central

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

Herrmann, Stefan; Schnorr, Sabine; Ludwig, Andreas

2015-01-01

357

The Physics of Cardiac Fibrillation: Strings that kill  

NASA Astrophysics Data System (ADS)

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).

Bodenschatz, Eberhard

2009-03-01

358

Role of a novel maintained low-voltage-activated inward current permeable to sodium and calcium in pacemaking of insect neurosecretory neurons  

Microsoft Academic Search

Among ionic currents underlying neuronal pacemaker activity, low-threshold-activated calcium currents contribute to setting the threshold for spike firing. In the insect central nervous system, dorsal unpaired median (DUM) neurons are capable of generating spontaneous electrical activity. It has previously been shown that two distinct (transient and maintained) low-voltage-activated (LVA) calcium currents are responsible for the generation of the pacemaker potential.

Antoine Defaix; Bruno Lapied

2005-01-01

359

Cardiac Asystole During Head Up Tilt (HUTT) in Children and Adolescents: Is this Benign Physiology?  

PubMed

Cardiac asystole during HUTT has been described by some investigators as a benign finding with no major sequelae. Our aim in this study is to correlate the severity of clinical symptoms and physiologic findings prior and during the asystole occurrence. This is a retrospective study review of 536 patients who underwent HUTT for dysautonomia symptoms for the last 3 years. HUTT in our institution consists of 10 min in supine, 30 min of head up at 70°, and recline to supine for 10 min. Physiologic parameters recorded include continuous heart rate, BP, cardiac stroke volume, brain blood flow by near-infra red spectroscopy, sympathetic and parasympathetic tones. Patients' complaints and signs during HUTT were recorded. Follow-up was conducted up to 34 months. Cardiac asystole was defined as the absence of ventricular activity for ?3 s with cessation of BP signal for the same period on the monitor. Of the 536 patients studied, 25 patients developed cardiac asystole (4.7 %). The asystolic group age was 15.1 + 3.8 years and weighed 56.7 + 21 kg. All the patients fainted and were not able to complete the test with average head up time of 13.8 + 7.1 min. The cardiac asystole duration was 9.2 + 5.8 s. Sixteen patients developed convulsions during the asystole. There was sudden intense vagal tone prior to and during the asystole. Brain perfusion was significantly decreased in all the patients after head up and sharply dropped by 20-35 % in patients who developed convulsions. All patients completely recovered their consciousness after reposition to supine. During recovery, there was overshoot of the brain perfusion above the baseline for several minutes and the HR returned to baseline. Follow-up of these patients: only one patient had a single lead pacemaker, otherwise the 24 patients had no cardiac pacing and were treated by medical therapy. During mean follow-up of 19 + 10 months, five patients developed syncope which resolved after optimizing medical therapy. Cardiac asystole due to neurocardiogenic syncope and dysautonomia has high association with brain anoxia that can lead to convulsions. Such patients require intense medical therapy and close observation with possible intervention by cardiac pacing if prolonged asystole occurs. There is a concern of consequence future brain function. PMID:25087055

Numan, Mohammed; Alnajjar, Rawan; Lankford, Jeremy; Gourishankar, Anand; Butler, Ian

2015-01-01

360

Cardiac arrhythmogenesis and temperature.  

PubMed

Fast processes in cardiac electrophysiology are often studied at temperatures lower than physiological. Extrapolation of values is based on widely accepted Q10 (Arrhenius) model of temperature dependence (ratio of kinetic properties for a 10 degrees C change in temperature). In this study, we set out to quantify the temperature dependence of essential parameters that define spatiotemporal behavior of cardiac excitation. Additionally, we examined temperature's effects on restitution dynamics. We employed fast fluorescence imaging with voltage-and calcium-sensitive dyes in neonatal rat cardiomyocyte sheets. Conduction velocity (CV), calcium transient duration (CTD), action potential duration (APD) and wavelength (W=CV*duration) change as functions of temperature were quantified. Using 24 degrees C as a reference point, we found a strong temperature-driven increase of CV (Q10=2.3) with smaller CTD and APD changes (Q10=1.33, 1.24, respectively). The spatial equivalents of voltage and calcium duration, wavelength, were slightly less sensitive to temperature with Q10=2.05 and 1.78, respectively, due to the opposing influences of decreasing duration with increased velocity. More importantly, we found that Q10 varies as a function of diastolic interval. Our results indicate the importance of examining temperature sensitivity across several frequencies. Armed with our results, experimentalists and modelers alike have a tool for reconciling different environmental conditions. In a broader sense, these data help better understand thermal influences on arrhythmia development or suppression such as during hibernation or cardiac surgery. PMID:17946861

Shah, Ujas; Bien, Harold; Entcheva, Emilia

2006-01-01

361

Two-oscillator structure of the pacemaker controlling the circadian rhythm of N-acetyltransferase in the rat pineal gland  

Microsoft Academic Search

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

Helena Illnerová; Ji?í Van??ek

1982-01-01

362

Coupling of a Core Post-Translational Pacemaker to a Slave Transcription/Translation Feedback Loop in a Circadian System  

PubMed Central

Cyanobacteria are the only model circadian clock system in which a circadian oscillator can be reconstituted in vitro. The underlying circadian mechanism appears to comprise two subcomponents: a post-translational oscillator (PTO) and a transcriptional/translational feedback loop (TTFL). The PTO and TTFL have been hypothesized to operate as dual oscillator systems in cyanobacteria. However, we find that they have a definite hierarchical interdependency—the PTO is the core pacemaker while the TTFL is a slave oscillator that quickly damps when the PTO stops. By analysis of overexpression experiments and mutant clock proteins, we find that the circadian system is dependent upon the PTO and that suppression of the PTO leads to damped TTFL-based oscillations whose temperature compensation is not stable under different metabolic conditions. Mathematical modeling indicates that the experimental data are compatible with a core PTO driving the TTFL; the combined PTO/TTFL system is resilient to noise. Moreover, the modeling indicates a mechanism by which the TTFL can feed into the PTO such that new synthesis of clock proteins can phase-shift or entrain the core PTO pacemaker. This prediction was experimentally tested and confirmed by entraining the in vivo circadian system with cycles of new clock protein synthesis that modulate the phosphorylation status of the clock proteins in the PTO. In cyanobacteria, the PTO is the self-sustained core pacemaker that can operate independently of the TTFL, but the TTFL damps when the phosphorylation status of the PTO is clamped. However, the TTFL can provide entraining input into the PTO. This study is the first to our knowledge to experimentally and theoretically investigate the dynamics of a circadian clock in which a PTO is coupled to a TTFL. These results have important implications for eukaryotic clock systems in that they can explain how a TTFL could appear to be a core circadian clockwork when in fact the true pacemaker is an embedded biochemical oscillator. PMID:20563306

Xu, Yao; Mori, Tetsuya; Johnson, Carl Hirschie

2010-01-01

363

Cardiac Emergencies in Neurosurgical Patients  

PubMed Central

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.

Petropolis, Andrea; Cappellani, Ronald B.

2015-01-01

364

Simulation of Cardiac Action Potentials  

Microsoft Academic Search

\\u000a Simulation of cardiac action potentials offers a brief introduction to cardiac action potential modeling by examining the\\u000a history of the field and discusses experimental and modeling breakthroughs that have yielded today’s current models. The chapter\\u000a begins with an overview of the cardiac action potential and highlights the Hodgkin and Huxley formalism. The chapter then\\u000a highlights specific key models with a

Jonathan D. Moreno; Colleen E. Clancy

365

Neuregulin/ErbB Signaling Regulates Cardiac Subtype Specification in Differentiating Human Embryonic Stem Cells  

PubMed Central

Rationale Human embryonic stem cell-derived cardiomyocytes (hESC-CMs) exhibit either a “working” chamber or a nodal-like phenotype. To generate optimal hESC-CM preparations for eventual clinical application in cell-based therapies, we will need to control their differentiation into these specialized cardiac subtypes. Objective To demonstrate intact neuregulin-1? (NRG-1?)/ErbB signaling in hESC-CMs and test the hypothesis that this signaling pathway regulates cardiac subtype abundance in hESC-CM cultures. Methods & Results All experiments employed hESC-CM cultures generated using our recently reported directed differentiation protocol. To support subsequent action potential phenotyping approaches and provide a higher-throughput method of determining cardiac subtype, we first developed and validated a novel genetic label that identifies nodal-type hESC-CMs. Next, control hESC-CM preparations were compared to those differentiated in the presence of exogenous NRG-1?, an anti-NRG-1? neutralizing antibody, or the ErbB antagonist AG1478. We used three independent approaches to determine the ratio of cardiac subtypes in the resultant populations: direct action potential phenotyping under current-clamp, activation of the aforementioned genetic label, and subtype-specific marker expression by RT-PCR. Using all three endpoints, we found that inhibition of NRG-1?/ErbB signaling greatly enhanced the proportion of cells showing the nodal phenotype. Conclusions NRG-1?/ErbB signaling regulates the ratio of nodal- to working-type cells in differentiating hESC-CM cultures and presumably functions similarly during early human heart development. We speculate that, by manipulating NRG-1?/ErbB signaling, it will be possible to generate preparations of enriched working-type myocytes for infarct repair, or, conversely, nodal cells for potential use in a biological pacemaker. PMID:20671236

Zhu, Wei-Zhong; Xie, Yiheng; Moyes, Kara White; Gold, Joseph D.; Askari, Bardia; Laflamme, Michael A.

2010-01-01

366

Correlates of objectively measured physical activity in cardiac patients  

PubMed Central

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

Ozemek, Cemal; Riggin, Katrina; Strath, Scott; Kaminsky, Leonard

2014-01-01

367

Independent Association between Acute Renal Failure and Mortality following Cardiac Surgery 1 1 Access the “Journal Club” discussion of this paper at http:\\/\\/www.elsevier.com\\/locate\\/ajmselect\\/ 2 2 The VA Continuous Improvement in Cardiac Surgery Program was initially supported by the Health Services Research and Development Service, Veterans Health Administration, and funded through VA Patient Care Services  

Microsoft Academic Search

Purpose: To determine whether there is an independent association of acute renal failure requiring dialysis with operative mortality after cardiac surgery.Patients and Methods: The 42,773 patients who underwent coronary artery bypass or valvular heart surgery at 43 Department of Veterans Affairs Medical Centers between 1987 and 1994 were evaluated to determine the association between acute renal failure sufficient to require

Glenn M Chertow; Elliott M Levy; Karl E Hammermeister; Frederick Grover; Jennifer Daley

1998-01-01

368

Cardiac troponins: bench to bedside interpretation in cardiac disease.  

PubMed

Cardiac troponins are the preferred biomarkers for the determination of acute myocardial necrosis. The high sensitivity of the available assays has significantly increased the detection of microscopic amounts of myocardial damage. Although compelling evidence indicates that elevated cardiac troponins are markers of poor prognosis and increased mortality, irrespective of the clinical scenario, small elevations can be seen in protean conditions and may confound the diagnosis of acute coronary syndromes. Emerging evidence suggests multiple different cellular mechanisms leading to cardiac troponin release, which challenge long held paradigms such as equivalency between troponin release into the circulation and irreversible cell death. Hence, knowledge of the physiology and pathophysiology of these cardiac biomarkers is essential for their accurate interpretation and consequent correct clinical diagnosis. Herein, the current relevant information about cardiac troponins is discussed, with special emphasis on pathophysiology and clinical correlates. PMID:23656921

Muthu, Vasundhara; Kozman, Hani; Liu, Kan; Smulyan, Harold; Villarreal, Daniel

2014-04-01

369

UPDATE: CARDIAC XENOTRANSPLANTATION  

PubMed Central

Purpose of review To review the latest development in cardiac xenotransplantation in small and large animal models and related in vitro studies. Recent findings With the recent introduction of ?1,3-galactosyltransferase gene-knockout (GT-KO) pig organs for xenotransplantation, improved cardiac graft survival has been obtained. However, this experience has demonstrated the importance of pig antigens other than Gal?1,3Gal (Gal) antigens (so-called nonGal antigens) as targets for primate anti-pig antibodies. Several in vitro studies have confirmed that, although the incidence and levels of anti-nonGal antibodies in non-human primates and humans are significantly less when compared with total anti-pig antibodies (i.e., anti-Gal + anti-nonGal), they can result in complement-mediated lysis of GT-KO pig cells. More recently, it has been demonstrated that regulatory T cells (Treg) suppress the cellular xenogeneic response, thus potentially preventing or reducing T cell-mediated rejection. The importance of thrombotic microangiopathy as a feature of the immune/inflammatory response and incompatibilities between the coagulation-anticoagulation systems of pig and primate are receiving increasing attention. Development of GT-KO pigs transgenic for one or more ‘anti-thrombotic’ genes, e.g., CD39 or tissue factor pathway inhibitor, may contribute to overcoming these problems. Summary Although GT-KO pigs have provided an advance over wild-type pigs as a source of Organs for transplantation into primates, further genetic modification of GT-KO pigs is required to overcome the remaining immune barriers before a clinical trial of cardiac xenotransplantation can be contemplated. PMID:19060538

Ekser, Burcin; Cooper, David K.C.

2009-01-01

370

Alterations induced by chronic lead exposure on the cells of circadian pacemaker of developing rats  

PubMed Central

Lead (Pb) exposure alters the temporal organization of several physiological and behavioural processes in which the suprachiasmatic nucleus (SCN) of the hypothalamus plays a fundamental role. In this study, we evaluated the effects of chronic early Pb exposure (CePbe) on the morphology, cellular density and relative optical density (OD) in the cells of the SCN of male rats. Female Wistar rats were exposed during gestation and lactation to a Pb solution containing 320 ppm of Pb acetate through drinking water. After weaning, the pups were maintained with the same drinking water until sacrificed at 90 days of age. Pb levels in the blood, hypothalamus, hippocampus and prefrontal cortex were significantly increased in the experimental group. Chronic early Pb exposure induced a significant increase in the minor and major axes and somatic area of vasoactive intestinal polypeptide (VIP)- and vasopressin (VP)-immunoreactive neurons. The density of VIP-, VP- and glial fibrillary acidic protein (GFAP)-immunoreactive cells showed a significant decrease in the experimental group. OD analysis showed a significant increase in VIP neurons of the experimental group. The results showed that CePbe induced alterations in the cells of the SCN, as evidenced by modifications in soma morphology, cellular density and OD in circadian pacemaker cells. These findings provide a morphological and cellular basis for deficits in circadian rhythms documented in Pb-exposed animals. PMID:21324006

Rojas-Castañeda, Julio César; Vigueras-Villaseñor, Rosa María; Rojas, Patricia; Chávez-Saldaña, Margarita; Pérez, Oscar Gutiérrez; Montes, Sergio; Ríos, Camilo

2011-01-01

371

Epigenetic Regulation of Axonal Growth of Drosophila Pacemaker Cells by Histone Acetyltransferase Tip60 Controls Sleep  

PubMed Central

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

Pirooznia, Sheila K.; Chiu, Kellie; Chan, May T.; Zimmerman, John E.; Elefant, Felice

2012-01-01

372

Experimental observation of transition from chaotic bursting to chaotic spiking in a neural pacemaker  

NASA Astrophysics Data System (ADS)

The transition from chaotic bursting to chaotic spiking has been simulated and analyzed in theoretical neuronal models. In the present study, we report experimental observations in a neural pacemaker of a transition from chaotic bursting to chaotic spiking within a bifurcation scenario from period-1 bursting to period-1 spiking. This was induced by adjusting extracellular calcium or potassium concentrations. The bifurcation scenario began from period-doubling bifurcations or period-adding sequences of bursting pattern. This chaotic bursting is characterized by alternations between multiple continuous spikes and a long duration of quiescence, whereas chaotic spiking is comprised of fast, continuous spikes without periods of quiescence. Chaotic bursting changed to chaotic spiking as long interspike intervals (ISIs) of quiescence disappeared within bursting patterns, drastically decreasing both ISIs and the magnitude of the chaotic attractors. Deterministic structures of the chaotic bursting and spiking patterns are also identified by a short-term prediction. The experimental observations, which agree with published findings in theoretical neuronal models, demonstrate the existence and reveal the dynamics of a neuronal transition from chaotic bursting to chaotic spiking in the nervous system.

Gu, Huaguang

2013-06-01

373

Epigenetic regulation of axonal growth of Drosophila pacemaker cells by histone acetyltransferase tip60 controls sleep.  

PubMed

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

Pirooznia, Sheila K; Chiu, Kellie; Chan, May T; Zimmerman, John E; Elefant, Felice

2012-12-01

374

Retrograde bone morphogenetic protein signaling shapes a key circadian pacemaker circuit.  

PubMed

The neuropeptide pigment-dispersing factor (PDF) synchronizes molecular oscillations within circadian pacemakers in the Drosophila brain. It is expressed in the small ventral lateral neurons (sLNvs) and large ventral lateral neurons, the former being indispensable for maintaining behavioral rhythmicity under free-running conditions. How PDF circuits develop the specific connectivity traits that endow such global behavioral control remains unknown. Here, we show that mature sLNv circuits require PDF signaling during early development, acting through its cognate receptor PDFR at postsynaptic targets. Yet, axonal defects by PDF knockdown are presynaptic and become apparent only after metamorphosis, highlighting a delayed response to a signal released early on. Presynaptic expression of constitutively active bone morphogenetic protein (BMP) receptors prevents pdfr mutants misrouting phenotype, while sLNv-restricted downregulation of BMP signaling components phenocopied pdf(01). Thus, we have uncovered a novel mechanism that provides an early "tagging" of synaptic targets that will guide circuit refinement later in development. PMID:23303947

Gorostiza, E Axel; Ceriani, M Fernanda

2013-01-01

375

Electromagnetic immunity of implantable pacemakers exposed to wi-fi devices.  

PubMed

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

Mattei, Eugenio; Censi, Federica; Triventi, Michele; Calcagnini, Giovanni

2014-10-01

376

A 680 nA ECG Acquisition IC for Leadless Pacemaker Applications.  

PubMed

A sub- ?W ECG acquisition IC is presented for a single-chamber leadless pacemaker applications. It integrates a low-power, wide dynamic-range ECG readout front end together with an analog QRS-complex extractor. To save ASIC power, a current-multiplexed channel buffer is introduced to drive a 7 b-to-10 b self-synchronized SAR ADC which utilizes 4 fF/unit capacitors. The ASIC consumes only 680nA and achieves CMRR > 90 dB, PSRR > 80 dB, an input-referred noise of 4.9 ?Vrms in a 130 Hz bandwidth, and has rail-to-rail DC offset rejection. Low-power heartbeat detections are evaluated with the help of the ASIC acquiring nearly 20,000 beats across 10 different records from the MIT-BIH arrhythmia database. In the presence of muscle noise, both the average Sensitivity (Se) and Positive Predictivity (PP) show more than 90% when the input SNR > 6 dB. PMID:25546862

Yan, Long; Harpe, Pieter; Pamula, Venkata Rajesh; Osawa, Masato; Harada, Yasunari; Tamiya, Kosei; Van Hoof, Chris; Yazicioglu, Refet Firat

2014-12-01

377

The quality of cardiac rehabilitation in Canada: a report of the Canadian Cardiac Rehab Registry.  

PubMed

Cardiac rehabilitation (CR) significantly reduces morbidity and mortality compared with usual care. CR quality indicators (QIs) have recently been established in Canada. This article presents an assessment of real-world CR program achievement of process and outcome QIs in Canada, using the Canadian Cardiac Rehab Registry (CCRR). The CR QIs were developed through the Canadian Cardiovascular Society's Best Practice Methodology. After reconciling the QI with CCRR definitions, it was identified that 14 (46.7%) of the 30 QIs could be assessed through the CCRR. There were 5447 patient records from 11 CR programs in the CCRR. Wait times exceeded the 30-day QI target, at a median of 84 days from referral to enrollment. Assessment of QIs of blood pressure (90%) and adiposity (85%) were high, however assessment of QIs for lipids (41%), blood glucose among patients with diabetes (23%), and depression overall (13%) were low. A majority of the participants (68%) achieved the half metabolic equivalent increase in the exercise capacity QI from CR program entry to exit. Of smokers, only 61% were offered smoking cessation therapy. Thirty percent of participants were offered stress management. The CR program completion QI was met in 90% of patients. Areas for care and quality improvement have been identified for the CR community in Canada. Efforts to engage more CR programs assess a greater number of QIs, and to feed back the findings to participating programs quarterly are currently under way. PMID:25442441

Grace, Sherry L; Parsons, Trisha L; Duhamel, Todd A; Somanader, Deborah S; Suskin, Neville

2014-11-01

378

Current perspectives on cardiac amyloidosis  

PubMed Central

Amyloidosis represents a group of diseases in which proteins undergo misfolding to form insoluble fibrils with subsequent tissue deposition. While almost all deposited amyloid fibers share a common nonbranched morphology, the affected end organs, clinical presentation, treatment strategies, and prognosis vary greatly among this group of diseases and are largely dependent on the specific amyloid precursor protein. To date, at least 27 precursor proteins have been identified to result in either local tissue or systemic amyloidosis, with nine of them manifesting in cardiac deposition and resulting in a syndrome termed “cardiac amyloidosis” or “amyloid cardiomyopathy.” Although cardiac amyloidosis has been traditionally considered to be a rare disorder, as clinical appreciation and understanding continues to grow, so too has the prevalence, suggesting that this disease may be greatly underdiagnosed. The most common form of cardiac amyloidosis is associated with circulating amyloidogenic monoclonal immunoglobulin light chain proteins. Other major cardiac amyloidoses result from a misfolding of products of mutated or wild-type transthyretin protein. While the various cardiac amyloidoses share a common functional consequence, namely, an infiltrative cardiomyopathy with restrictive pathophysiology leading to progressive heart failure, the underlying pathophysiology and clinical syndrome varies with each precursor protein. Herein, we aim to provide an up-to-date overview of cardiac amyloidosis from nomenclature to molecular mechanisms and treatment options, with a particular focus on amyloidogenic immunoglobulin light chain protein cardiac amyloidosis. PMID:22058156

Guan, Jian; Mishra, Shikha; Falk, Rodney H.

2012-01-01

379

Redox Control of Cardiac Excitability  

PubMed Central

Abstract Reactive oxygen species (ROS) have been associated with various human diseases, and considerable attention has been paid to investigate their physiological effects. Various ROS are synthesized in the mitochondria and accumulate in the cytoplasm if the cellular antioxidant defense mechanism fails. The critical balance of this ROS synthesis and antioxidant defense systems is termed the redox system of the cell. Various cardiovascular diseases have also been affected by redox to different degrees. ROS have been indicated as both detrimental and protective, via different cellular pathways, for cardiac myocyte functions, electrophysiology, and pharmacology. Mostly, the ROS functions depend on the type and amount of ROS synthesized. While the literature clearly indicates ROS effects on cardiac contractility, their effects on cardiac excitability are relatively under appreciated. Cardiac excitability depends on the functions of various cardiac sarcolemal or mitochondrial ion channels carrying various depolarizing or repolarizing currents that also maintain cellular ionic homeostasis. ROS alter the functions of these ion channels to various degrees to determine excitability by affecting the cellular resting potential and the morphology of the cardiac action potential. Thus, redox balance regulates cardiac excitability, and under pathological regulation, may alter action potential propagation to cause arrhythmia. Understanding how redox affects cellular excitability may lead to potential prophylaxis or treatment for various arrhythmias. This review will focus on the studies of redox and cardiac excitation. Antioxid. Redox Signal. 18, 432–468. PMID:22897788

Aggarwal, Nitin T.

2013-01-01

380

The Chemotherapy of Cardiac Arrest  

PubMed Central

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

Minuck, Max

1965-01-01

381

Challenges in Cardiac Tissue Engineering  

PubMed Central

Cardiac tissue engineering aims to create functional tissue constructs that can reestablish the structure and function of injured myocardium. Engineered constructs can also serve as high-fidelity models for studies of cardiac development and disease. In a general case, the biological potential of the cell—the actual “tissue engineer”—is mobilized by providing highly controllable three-dimensional environments that can mediate cell differentiation and functional assembly. For cardiac regeneration, some of the key requirements that need to be met are the selection of a human cell source, establishment of cardiac tissue matrix, electromechanical cell coupling, robust and stable contractile function, and functional vascularization. We review here the potential and challenges of cardiac tissue engineering for developing therapies that could prevent or reverse heart failure. PMID:19698068

Tandon, Nina; Godier, Amandine; Maidhof, Robert; Marsano, Anna; Martens, Timothy P.; Radisic, Milica

2010-01-01

382

[No compression of cardiac cavities in transthoracic ultrasound does not exclude cardiac tamponade.  

PubMed

The clinical presentation of cardiac tamponade is difficult to distinguish from other causes of shock. Pericardial fluid is easy to visualize with cardiac ultrasound and a key sign of overt cardiac tamponade is the compression of right side cavities. We present two cases in which cardiac tamponade was present, but where compression of cardiac cavities could not be demon-strated with transthoracic cardiac ultrasound. This emphasizes that cardiac tamponade is still a clinical diagnosis. PMID:25430575

Juhl-Olsen, Peter; Frederiksen, Christina Alcaraz; Sloth, Erik

2014-11-24

383

Concrete induced cardiac contusion.  

PubMed

A previously fit 22 year old man was struck in the chest by a concrete block dropped through the windscreen of his car while he was driving on the motorway. He suffered extensive chest wall trauma and lung contusion, which subsequently precipitated acute respiratory distress. On admission ECG showed right bundle branch block and left axis deviation. Three days later QRS duration was normal but there was anterior ST segment elevation and subsequent T wave change. There was a large rise in creatine kinase, and echocardiography revealed septal and apical hyokinesis as well as a mobile mass attached to the left side of the interventricular septum, which had the echogenic texture of myocardium. The patient had fixed perfusion defects in the areas of hypokinesis on thallium scanning but the coronary arteries were unobstructed at angiography. He was treated with warfarin in the short term and an angiotensin converting enzyme inhibitor in the longer term and has made an asymptomatic recovery. Outpatient echocardiography two months after the injury demonstrated some recovery in overall left ventricular systolic function and no evidence of the intracardiac mass. This case illustrates some of the typical features of non-fatal cardiac contusion associated with non-penetrating cardiac trauma, and was complicated by partial thickness avulsion of a strip of the myocardium in the interventricular septum. PMID:9391297

Curzen, N; Brett, S; Fox, K

1997-09-01

384

Comprehensive cardiovascular disease risk reduction in a cardiac rehabilitation setting.  

PubMed

Cardiac rehabilitation combines prescriptive exercise training with coronary artery disease (CAD) risk factor modification in patients with established CAD. As such, cardiac rehabilitation programs are ideally positioned to assume a pivotal role in the rendering of many components of comprehensive cardiovascular disease risk reduction in a secondary prevention setting. However, the extent to which traditional cardiac rehabilitation programs can successfully accomplish this goal is limited by low participation rates, inadequate emphasis on many of the essential aspects of secondary prevention, and lack of long-term follow-up of patients. To overcome these deficiencies, cardiac rehabilitation programs should evolve into cardiovascular risk reduction programs by implementing approaches that have been shown to be effective in randomized clinical trials. In this manuscript we describe one such approach, based on the Stanford Coronary Risk Intervention Project, which has been implemented in > 1,000 patients. Key components of this physician-supervised, nurse case-manager model include: (1) initial evaluation and risk assessment; (2) identification of specific goals for each CAD risk factor; (3) formulation and implementation of an individualized treatment plan that includes lifestyle modification and pharmacologic interventions for accomplishing specific risk reduction goals; (4) long-term follow-up to enhance compliance and revise the treatment plan as indicated; and (5) a mechanism for outcomes based long-term assessment of each patient. PMID:9373003

Gordon, N F; Haskell, W L

1997-10-30

385

Distribution of guidance models for cardiac resynchronization therapy in the setting of multi-center clinical trials  

NASA Astrophysics Data System (ADS)

Multi-center trials provide the unique ability to investigate novel techniques across a range of geographical sites with sufficient statistical power, the inclusion of multiple operators determining feasibility under a wider array of clinical environments and work-flows. For this purpose, we introduce a new means of distributing pre-procedural cardiac models for image-guided interventions across a large scale multi-center trial. In this method, a single core facility is responsible for image processing, employing a novel web-based interface for model visualization and distribution. The requirements for such an interface, being WebGL-based, are minimal and well within the realms of accessibility for participating centers. We then demonstrate the accuracy of our approach using a single-center pacemaker lead implantation trial with generic planning models.

Rajchl, Martin; Abhari, Kamyar; Stirrat, John; Ukwatta, Eranga; Cantor, Diego; Li, Feng P.; Peters, Terry M.; White, James A.

2014-03-01

386

40years of cardiac rehabilitation and secondary prevention in post-cardiac ischaemic patients. Are we still in the wilderness?  

PubMed

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 20years 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

Jelinek, Michael V; Thompson, David R; Ski, Chantal; Bunker, Stephen; Vale, Margarite J

2015-01-20

387

Contractile reserve assessed by dobutamine test identifies super-responders to cardiac resynchronization therapy  

PubMed Central

Introduction In this study, we sought to determine whether myocardial contractile reserve (CR) assessed by dobutamine stress echocardiography (DSE) can identify patients who experience nearly complete normalization of left ventricular (LV) function after the implantation of a cardiac resynchronization therapy (CRT) pacemaker. Material and methods The study group consisted of 55 consecutive patients with non-ischemic dilated cardiomyopathy, LV ejection fraction (LVEF) < 35%, and prolonged QRS complex duration, who were scheduled for CRT pacemaker implantation. The DSE (20 µg/kg/min) was performed in all patients. The CR assessment was based on a change in the wall motion score index (?WMSI) and ?LVEF during DSE. Super-response was defined as an increase in LVEF to > 50% and reduction in left ventricular end-systolic dimension to < 40 mm 12 months following the CRT implantation. Results A total of 7 patients (12.7%) were identified as super-responders to CRT. When compared to non-super-responders, these patients had significantly higher values of the dobutamine-induced change in ?WMSI (1.031 ±0.120 vs. 0.49 ±0.371, p < 0.01), and ?EF (17.9 ±2.2 vs. 8.8 ±6.2, p < 0.01). Receiver operating characteristic analysis showed that dobutamine-induced changes in ?WMSI ? 0.7 and ? 14% for ?EF are the best discriminators for a super-response. Patients with ?WMSI ? 0.7 and ?EF ? 14% are significantly less often hospitalized (p < 0.01) for worsening of heart failure during 28.5 ±3.0 months of the follow-up. Conclusions Contractile reserve assessed by DSE can identify patients with dilated cardiomyopathy who are likely to experience near normalization of LV function following CRT. PMID:25276151

Milasinovic, Goran; Angelkov, Lazar; Ristic, Velibor; Tomovic, Milosav; Jurcevic, Ruzica; Otasevic, Petar

2014-01-01

388

Coronary spasm during cardiac electrophysiological study following isoproterenol infusion  

PubMed Central

Sudden cardiac death (SCD) remains the leading cause of death in industrialized world. The majority of SCD is caused by ventricular fibrillation associated with structural and/or ischemic heart disease. Ventricular fibrillation represents the final common pathway for SCD and, thus, is an attractive target for ablation. According to class I recommendation level of evidence A, an implantable cardioverter defibrillator (ICD) should be implanted for such patients [1]. Other than programmed electrical extrastimulus technique, isoproterenol infusion is commonly used in invasive cardiac electrophysiology labs for arrhythmia induction. We hereby report a rare case of transient coronary spasm during isoproterenol infusion for ventricular tachycardia induction testing. PMID:25598993

Aksoy, Ismail; Phan, Kevin; Vainer, Jindra; Timmermans, Carl

2014-01-01

389

The influence of pacing rate and autonomic blockade on human primary and secondary atrial pacemakers.  

PubMed

The morphology of the first spontaneous post-pacing P wave was assessed in 106 patients who underwent electrophysiological study for various arrhythmias. An overall number of 589 atrial pacing sessions, from 60-200 b/min, were analyzed (mean 5.55 +/- 1.3 session per patient). After cessation of 138 (23.42%) of them, spontaneous post-pacing P wave arose from extrasinus foci. Nonsinus spontaneous post-pacing P waves were recorded after 1 or more pacing rates (from 1 to 7) in 58 patients (54.7%, Group 1). In the remaining 48 patients the spontaneous post-pacing P waves were sinus after all pacing sessions (45.3%, Group 2). Sinus node disease (SND) was present in 32.7% of Group 1 patients and in 2% of Group 2 (p = 0.002). Spontaneous post-pacing P wave of extrasinus origin was recorded in 19/20 of SND patients (95%) compared to 39/86 of patients with normal sinus function (45.34%, p < 0.001). SND patients had a greater number of pacing sessions resulting in nonsinus spontaneous post-pacing P waves. Pacing rate associated with nonsinus spontaneous post-pacing P waves was lower in SND patients compared to patients with normal sinus node function. In the SND group, nonsinus spontaneous post-pacing P waves were recorded beyond the first spontaneous one in 9 patients compared to only 1 in patients with normal sinus node function (p < 0.005). Extrasinusal first spontaneous post-pacing P waves at a pacing rate of 140 b/min had the highest sensitivity (75%). Increasing of pacing rate from 60 to 140 b/min was associated with progressive arousal of secondary foci with highest value of 36.8% in pacing rate of 140 b/min. Further increase of pacing rate resulted in a slight reduction of spontaneous post-pacing firing from secondary foci. Atropine was administered in 12 Group 1 patients and abolished all measurable morphological changes of spontaneous post-pacing P waves compared to pre-pacing. Autonomic blockade was performed in 14 Group 1 patients and 16 Group 2 patients. In 35.7% of Group 1 patients autonomic blockade abolished the appearance of nonsinus spontaneous post-pacing P waves, while in the remaining patients increased the lowest pacing rate resulting in nonsinus spontaneous post-pacing P waves. In 12.5% Group 2 patients autonomic blockade resulted in nonsinus spontaneous post-pacing P waves after cessation of atrial pacing. In conclusion, the extrasinus spontaneous rise of atrial impulse is a very frequent phenomenon after atrial pacing especially in patients with SND. Pacing rate has different quantitative effects on sinus and secondary atrial pacemakers. Secondary pacemakers are less under autonomic control compared to sinus node. PMID:9611857

Ndrepepa, G; Cina, P; Gjini, V; Kondili, A; Balla, I; Kastrati, A

1998-03-01

390

Metoclopramide-induced cardiac arrest  

PubMed Central

The authors report a case of cardiac arrest in a patient receiving intravenous (IV) metoclopramide and review the pertinent literature. A 62-year-old morbidly obese female admitted for a gastric sleeve procedure, developed cardiac arrest within one minute of receiving metoclopramide 10 mg via slow intravenous (IV) injection. Bradycardia at 4 beats/min immediately appeared, progressing rapidly to asystole. Chest compressions restored vital function. Electrocardiogram (ECG) revealed ST depression indicative of myocardial injury. Following intubation, the patient was transferred to the intensive care unit. Various cardiac dysrrhythmias including supraventricular tachycardia (SVT) associated with hypertension and atrial fibrillation occurred. Following IV esmolol and metoprolol, the patient reverted to normal sinus rhythm. Repeat ECGs revealed ST depression resolution without pre-admission changes. Metoclopramide is a non-specific dopamine receptor antagonist. Seven cases of cardiac arrest and one of sinus arrest with metoclopramide were found in the literature. The metoclopramide prescribing information does not list precautions or adverse drug reactions (ADRs) related to cardiac arrest. The reaction is not dose related but may relate to the IV administration route. Coronary artery disease was the sole risk factor identified. According to Naranjo, the association was possible. Other reports of cardiac arrest, severe bradycardia, and SVT were reviewed. In one case, five separate IV doses of 10 mg metoclopramide were immediately followed by asystole repeatedly. The mechanism(s) underlying metoclopramide's cardiac arrest-inducing effects is unknown. Structural similarities to procainamide may play a role. In view of eight previous cases of cardiac arrest from metoclopramide having been reported, further elucidation of this ADR and patient monitoring is needed. Our report should alert clinicians to monitor patients and remain diligent in surveillance and reporting of bradydysrrhythmias and cardiac arrest in patients receiving metoclopramide. PMID:24765383

Rumore, Martha M.; Lee, Spencer Evan; Wang, Steven; Farmer, Brenna

2011-01-01

391

PREGLED ELEKTROSTIMULACIJE SRCA V SPLOŠNI BOLNIŠNICI MARIBOR OD LETA 1972 DO DANES REVIEW OF CARDIAC PACING AT MARIBOR TEACHING HOSPITAL SINCE 1972  

Microsoft Academic Search

Background. Number of implanted pacemakers is in continuous increase in Maribor General Hospital. The first four pacemakers in 1972 were followed by 50 pace- makers annually in the first 10 years. In 1988 the number first exceeded 100 implanted pacemakers and in the year 2004 achieved number 372. Altogether, till the end of the year 2004 there were 4232 pacemakers

Zlatko Pehnec

392

Peripartum cardiac failure  

PubMed Central

Peripartum cardiac failure (PPCF) is common in Zaria, in northern Nigeria, but has not been described elsewhere in Nigeria except in Ibadan. The geographic origin of a series of 224 patients with PPCF was studied in Zaria, and a survey of the syndrome as seen in hospitals and by physicians in the northern states of Nigeria was carried out; information was also gathered from medical and nursing students from various tribal groups in the same area. It was found that PPCF is only common in the areas of Hausa majority, mostly around Zaria and Malumfashi, where the postpartum practices of taking hot baths, lying on a hot bed, and taking large amounts of kanwa (a lake-salt rich in sodium) are pursued with great vigour. These customs may impose a critical load on a vulnerable myocardium, and it seems that tribe and tradition could well explain the high incidence of PPCF around Zaria. PMID:4549486

Davidson, N. McD.; Trevitt, Lorna; Parry, E. H. O.

1974-01-01

393

The presence of pacemaker HCN channels identifies theta rhythmic GABAergic neurons in the medial septum  

PubMed Central

The medial septum (MS) is an indispensable component of the subcortical network which synchronizes the hippocampus at theta frequency during specific stages of information processing. GABAergic neurons exhibiting highly regular firing coupled to the hippocampal theta rhythm are thought to form the core of the MS rhythm-generating network. In recent studies the hyperpolarization-activated, cyclic nucleotide-gated non-selective cation (HCN) channel was shown to participate in theta synchronization of the medial septum. Here, we tested the hypothesis that HCN channel expression correlates with theta modulated firing behaviour of MS neurons by a combined anatomical and electrophysiological approach. HCN-expressing neurons represented a subpopulation of GABAergic cells in the MS partly overlapping with parvalbumin (PV)-containing neurons. Rhythmic firing in the theta frequency range was characteristic of all HCN-expressing neurons. In contrast, only a minority of HCN-negative cells displayed theta related activity. All HCN cells had tight phase coupling to hippocampal theta waves. As a group, PV-expressing HCN neurons had a marked bimodal phase distribution, whereas PV-immunonegative HCN neurons did not show group-level phase preference despite significant individual phase coupling. Microiontophoretic blockade of HCN channels resulted in the reduction of discharge frequency, but theta rhythmic firing was perturbed only in a few cases. Our data imply that HCN-expressing GABAergic neurons provide rhythmic drive in all phases of the hippocampal theta activity. In most MS theta cells rhythm genesis is apparently determined by interactions at the level of the network rather than by the pacemaking property of HCN channels alone. PMID:18565991

Varga, Viktor; Hangya, Balázs; Kránitz, Kinga; Ludányi, Anikó; Zemankovics, Rita; Katona, István; Shigemoto, Ryuichi; Freund, Tamás F; Borhegyi, Zsolt

2008-01-01

394

Minimally Invasive Catheter Procedures to Assist Complicated Pacemaker Lead Extraction and Implantation in the Operating Room  

SciTech Connect

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.

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

395

Sex-specific role of a glutamate receptor subtype in a pacemaker nucleus controlling electric behavior.  

PubMed

Electric communication signals, produced by South American electric fish, vary across sexes and species and present an ideal opportunity to examine the bases of signal diversity, and in particular, the mechanisms underlying sexually dimorphic behavior. Gymnotiforms produce electric organ discharges (EOD) controlled by a hindbrain pacemaker nucleus (PN). Background studies have identified the general cellular mechanisms that underlie the production of communication signals, EOD chirps and interruptions, typically displayed in courtship and agonistic contexts. Brachyhypopomus gauderio emit sexually dimorphic signals, and recent studies have shown that the PN acquires the capability of generating chirps seasonally, only in breeding males, by modifying its glutamatergic system. We hypothesized that sexual dimorphism was caused by sexual differences in the roles of glutamate receptors. To test this hypothesis, we analyzed NMDA and AMPA mediated responses in PN slice preparations by field potential recordings, and quantified one AMPA subunit mRNA, in the PNs of males and females during the breeding season. In situ hybridization of GluR2B showed no sexual differences in quantities between the male and female PN. Functional responses of the PN to glutamate and AMPA, on the other hand, showed a clear cut sexual dimorphism. In breeding males, but not females, the PN responded to glutamate and AMPA with bursting activity, with a temporal pattern that resembled the pattern of EOD chirps. In this study, we have been successful in identifying cellular mechanisms of sexual dimorphic communication signals. The involvement of AMPA receptors in PN activity is part of the tightly regulated changes that account for the increase in signal diversity during breeding in this species, necessary for a successful reproduction. PMID:24794754

Quintana, Laura; Harvey-Girard, Erik; Lescano, Carolina; Macadar, Omar; Lorenzo, Daniel

2014-01-01

396

Cardiac action potential imaging  

NASA Astrophysics Data System (ADS)

Action potentials in cardiac myocytes have durations in the order of magnitude of 100 milliseconds. In biomedical investigations the documentation of the occurrence of action potentials is often not sufficient, but a recording of the shape of an action potential allows a functional estimation of several molecular players. Therefore a temporal resolution of around 500 images per second is compulsory. In the past such measurements have been performed with photometric approaches limiting the measurement to one cell at a time. In contrast, imaging allows reading out several cells at a time with additional spatial information. Recent developments in camera technologies allow the acquisition with the required speed and sensitivity. We performed action potential imaging on isolated adult cardiomyocytes of guinea pigs utilizing the fluorescent membrane potential sensor di-8-ANEPPS and latest electron-multiplication CCD as well as scientific CMOS cameras of several manufacturers. Furthermore, we characterized the signal to noise ratio of action potential signals of varying sets of cameras, dye concentrations and objective lenses. We ensured that di-8-ANEPPS itself did not alter action potentials by avoiding concentrations above 5 ?M. Based on these results we can conclude that imaging is a reliable method to read out action potentials. Compared to conventional current-clamp experiments, this optical approach allows a much higher throughput and due to its contact free concept leaving the cell to a much higher degree undisturbed. Action potential imaging based on isolated adult cardiomyocytes can be utilized in pharmacological cardiac safety screens bearing numerous advantages over approaches based on heterologous expression of hERG channels in cell lines.

Tian, Qinghai; Lipp, Peter; Kaestner, Lars

2013-06-01

397

Normal cardiac function in mice with supraphysiological cardiac creatine levels  

PubMed Central

Creatine and phosphocreatine levels are decreased in heart failure, and reductions in myocellular phosphocreatine levels predict the severity of the disease and portend adverse outcomes. Previous studies of transgenic mouse models with increased creatine content higher than two times baseline showed the development of heart failure and shortened lifespan. Given phosphocreatine's role in buffering ATP content, we tested the hypothesis whether elevated cardiac creatine content would alter cardiac function under normal physiological conditions. Here, we report the creation of transgenic mice that overexpress the human creatine transporter (CrT) in cardiac muscle under the control of the ?-myosin heavy chain promoter. Cardiac transgene expression was quantified by qRT-PCR, and human CrT protein expression was documented on Western blots and immunohistochemistry using a specific anti-CrT antibody. High-energy phosphate metabolites and cardiac function were measured in transgenic animals and compared with age-matched, wild-type controls. Adult transgenic animals showed increases of 5.7- and 4.7-fold in the content of creatine and free ADP, respectively. Phosphocreatine and ATP levels were two times as high in young transgenic animals but declined to control levels by the time the animals reached 8 wk of age. Transgenic mice appeared to be healthy and had normal life spans. Cardiac morphometry, conscious echocardiography, and pressure-volume loop studies demonstrated mild hypertrophy but normal function. Based on our characterization of the human CrT protein expression, creatine and phosphocreatine content, and cardiac morphometry and function, these transgenic mice provide an in vivo model for examining the therapeutic value of elevated creatine content for cardiac pathologies. PMID:24271489

Hernandez, Alejandro; Nienaber, Jeffrey; Mishra, Rajashree; Pinilla, Miguel; Burchette, James; Mao, Lan; Rockman, Howard A.; Jacobs, Danny O.

2013-01-01

398

Cardiac catheterization is underutilized after in-hospital cardiac arrest  

PubMed Central

Background Indications for immediate cardiac catheterization in cardiac arrest survivors without ST elevation myocardial infarction (STEMI) are uncertain as electrocardiographic and clinical criteria may be challenging to interpret in this population. We sought to evaluate rates of early catheterization after in-hospital ventricular fibrillation (VF) arrest and the association with survival. Methods Using a billing database we retrospectively identified cases with an ICD-9 code of cardiac arrest (427.5) or VF (427.41). Discharge summaries were reviewed to identify in-hospital VF arrests. Rates of catheterization on the day of arrest were determined by identifying billing charges. Unadjusted analyses were performed using chi square, and adjusted analyses were performed using logistic regression. Results 110 in-hospital VF arrest survivors were included in the analysis. Cardiac catheterization was performed immediately or within one day of arrest in 27% (30/110) of patients and of these patients, 57% (17/30) successfully received percutaneous coronary intervention. Of those who received cardiac catheterization the indication for the procedure was STEMI or new left bundle branch block (LBBB) in 43% (13/30). Therefore, in the absence of standard ECG data suggesting acute myocardial infarction, 57% (17/30) received angiography. Patients receiving cardiac catheterization were more likely to survive than those who did not receive catheterization (80% vs. 54%, p<.05). Conclusion In patients receiving cardiac catheterization, more than half received this procedure for indications other than STEMI or new LBBB. Cardiac catheterization was associated with improved survival. Future recommendations need to be established to guide clinicians on which arrest survivors might benefit from immediate catheterization. PMID:18951683

Merchant, Raina M.; Abella, Benjamin S.; Khan, Monica; Huang, Kuang-Ning; Beiser, David B.; Neumar, Robert W.; Carr, Brendan G.; Becker, Lance B.; Vanden Hoek, Terry L.

2009-01-01

399

Normal cardiac function in mice with supraphysiological cardiac creatine levels.  

PubMed

Creatine and phosphocreatine levels are decreased in heart failure, and reductions in myocellular phosphocreatine levels predict the severity of the disease and portend adverse outcomes. Previous studies of transgenic mouse models with increased creatine content higher than two times baseline showed the development of heart failure and shortened lifespan. Given phosphocreatine's role in buffering ATP content, we tested the hypothesis whether elevated cardiac creatine content would alter cardiac function under normal physiological conditions. Here, we report the creation of transgenic mice that overexpress the human creatine transporter (CrT) in cardiac muscle under the control of the ?-myosin heavy chain promoter. Cardiac transgene expression was quantified by qRT-PCR, and human CrT protein expression was documented on Western blots and immunohistochemistry using a specific anti-CrT antibody. High-energy phosphate metabolites and cardiac function were measured in transgenic animals and compared with age-matched, wild-type controls. Adult transgenic animals showed increases of 5.7- and 4.7-fold in the content of creatine and free ADP, respectively. Phosphocreatine and ATP levels were two times as high in young transgenic animals but declined to control levels by the time the animals reached 8 wk of age. Transgenic mice appeared to be healthy and had normal life spans. Cardiac morphometry, conscious echocardiography, and pressure-volume loop studies demonstrated mild hypertrophy but normal function. Based on our characterization of the human CrT protein expression, creatine and phosphocreatine content, and cardiac morphometry and function, these transgenic mice provide an in vivo model for examining the therapeutic value of elevated creatine content for cardiac pathologies. PMID:24271489

Santacruz, Lucia; Hernandez, Alejandro; Nienaber, Jeffrey; Mishra, Rajashree; Pinilla, Miguel; Burchette, James; Mao, Lan; Rockman, Howard A; Jacobs, Danny O

2014-02-01

400

Modified NPWT using round channel drain for pacemaker pocket non-healing complex wound: a case report.  

PubMed

Infection of cardiovascular implantable electronic devices poses a serious medical problem. Management of infected pocket wounds may be challenging for the physician and cause prolonged morbidity for the patient. The mainstay of treatment for infected cardiovascular implantable electronic devices is complete removal of the infected device and appropriate antibiotic therapy. In contrast, removal is not required for superficial or incisional infection at the pocket site if there is no involvement of the device. Here, we describe a modified negative pressure wound therapy (NPWT) technique using a round channel drain for pacemaker pocket non-healing complex wound, which started as a superficial incisional wound infection. PMID:25284298

Petit-Clair, N; Smith, M; Chernev, I

2014-09-01

401

Assessment of Diastolic Function by Cardiac MRI  

Microsoft Academic Search

Cardiac magnetic resonance imaging (MRI) techniques continue to change rapidly, and cardiac MRI is developing as an alternative\\u000a noninvasive technique having the unique potential of three-dimensional function analysis with great accuracy and reproducibility.\\u000a Advances in rapid cardiac MRI technology are making real-time imaging possible at approaching echocardiographic frame rates.\\u000a Together with the increasing availability of cardiac MRI machines, cardiac MRI

Bernard P. Paelinck; Hildo J. Lamb

402

Programming and Isolation of Highly Pure Physiologically and Pharmacologically Functional Sinus-Nodal Bodies from Pluripotent Stem Cells  

PubMed Central

Summary Therapeutic approaches for “sick sinus syndrome” rely on electrical pacemakers, which lack hormone responsiveness and bear hazards such as infection and battery failure. These issues may be overcome via “biological pacemakers” derived from pluripotent stem cells (PSCs). Here, we show that forward programming of PSCs with the nodal cell inducer TBX3 plus an additional Myh6-promoter-based antibiotic selection leads to cardiomyocyte aggregates consisting of >80% physiologically and pharmacologically functional pacemaker cells. These induced sinoatrial bodies (iSABs) exhibited highly increased beating rates (300–400 bpm), coming close to those found in mouse hearts, and were able to robustly pace myocardium ex vivo. Our study introduces iSABs as highly pure, functional nodal tissue that is derived from PSCs and may be important for future cell therapies and drug testing in vitro. PMID:24936448

Jung, Julia Jeannine; Husse, Britta; Rimmbach, Christian; Krebs, Stefan; Stieber, Juliane; Steinhoff, Gustav; Dendorfer, Andreas; Franz, Wolfgang-Michael; David, Robert

2014-01-01

403

Programs  

Cancer.gov

The Biorepositories and Biospecimen Research Branch is responsible for the direction and management of several programs. These include the Biospecimen Research Network, the NCI Best Practices for Biospecimen Resources, the Cancer Human Biobank (caHUB) and the Biospecimen Pre-Analytical Variables Program. Each program has specific goals and targeted outcomes which lend themselves to supporting the mission and vision of the Branch as well as the other NCI and NIH initiatives. More information about each program can be found on their respective pages.

404

Image guidance in cardiac electrophysiology  

E-print Network

Cardiac arrhythmias are characterized by a disruption or abnormal conduction of electrical signals within the heart. Treatment of arrhythmias has dramatically evolved over the past half-century, and today, minimally-invasive ...

Malchano, Zachary John

2006-01-01

405

BET acetyl-lysine binding proteins control pathological cardiac hypertrophy.  

PubMed

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

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

406

Pulmonary Hypertension in Cardiac Surgery  

PubMed Central

Pulmonary hypertension is an important prognostic factor in cardiac surgery associated with increased morbidity and mortality. With the aging population and the associated increase severity of illness, the prevalence of pulmonary hypertension in cardiac surgical patients will increase. In this review, the definition of pulmonary hypertension, the mechanisms and its relationship to right ventricular dysfunction will be presented. Finally, pharmacological and non-pharmacological therapeutic and preventive approaches will be presented. PMID:21286273

Denault, André; Deschamps, Alain; Tardif, Jean-Claude; Lambert, Jean; Perrault, Louis

2010-01-01

407

Can cardiac surgery cause hypopituitarism?  

Microsoft Academic Search

Apoplexy of pituitary adenomas with subsequent hypopituitarism is a rare but well recognized complication following cardiac\\u000a surgery. The nature of cardiac on-pump surgery provides a risk of damage to the pituitary because the vascular supply of the\\u000a pituitary is not included in the cerebral autoregulation. Thus, pituitary tissue may exhibit an increased susceptibility to\\u000a hypoperfusion, ischemia or intraoperative embolism. After

Flverly Francis; Ines Burger; Eva Maria Poll; Andrea Reineke; Christian J. Strasburger; Guido Dohmen; Joachim M. Gilsbach; Ilonka Kreitschmann-Andermahr

408

Cardiac manifestations in systemic sclerosis  

PubMed Central

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

Lambova, Sevdalina

2014-01-01

409

Sudden cardiac death in Athletes  

Microsoft Academic Search

The impact of sudden cardiac death (SCD) in athletes has been highlighted by increasing media coverage, as well as medical\\u000a and lay awareness of the entities associated with SCD. Common etiologies include cardiac abnormalities such as hypertrophic\\u000a cardiomyopathy (HCM), arrhythmogenic right ventricular dysplasia\\/cardiomyopathy (ARVD), and coronary artery anomalies, each\\u000a with varying geographic incidence. New recommendations regarding noninvasive preparticipation screening have

Olaf Hedrich; Mark Estes; Mark S. Link

2006-01-01

410

Cardiac assessment of veteran endurance athletes: a 12 year follow up study  

PubMed Central

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

Hood, S.; Northcote, R. J.

1999-01-01

411

Drosophila Models of Cardiac Disease  

PubMed Central

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

Piazza, Nicole; Wessells, R.J.

2013-01-01

412

Intrinsic near-24-h pacemaker period determines limits of circadian entrainment to a weak synchronizer in humans  

NASA Technical Reports Server (NTRS)

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.

Wright, K. P. Jr; Hughes, R. J.; Kronauer, R. E.; Dijk, D. J.; Czeisler, C. A.

2001-01-01

413

Recommendations for resistance exercise in cardiac rehabilitation. Recommendations of the German Federation for Cardiovascular Prevention and Rehabilitation  

Microsoft Academic Search

Aerobic endurance training has been an integral component of the international recommendations for cardiac rehabilitation for more than 30 years. Notwithstanding, only in recent years have recommendations for a dynamic resistance-training program been cautiously put forward. The perceived increased risk of cardiovascular complications related to blood pressure elevations are the primary concern with resistance training in cardiac patients; recent studies

B. Bjarnason-Wehrens; W. Mayer-Berger; E. R. Meister; K. Baum; R. Hambrecht; S. Gielen

2004-01-01

414

Cardiac achalasia in childhood  

PubMed Central

Cardiac achalasia is a disorder not unknown in the paediatric age-group and may occur even in the neonatal period. This disorder should, therefore, be considered in all cases presenting with persistent vomiting, as well as in those with chronic respiratory disease in whom more common causes have been excluded. It is almost universally accepted that the disorder results from a disturbed function of ganglion cells in the distal oesophagus, as the disease has been reproduced in laboratory animals by denervation of the distal oesophagus. The exact pathogenesis of this degenerative change is not well understood. However, in at least some of the cases congenital absence of the ganglion cells may be responsible for this functional disturbance. This is inferred from the fact that the disease may be found in association with Hirschsprung disease, in which there is a congenital absence of ganglion cells in the terminal colon. Moreover, the occurrence of the disease in the neonatal period itself favours a congenital lesion. Surgery was preferred to other forms of treatment in the paediatric age-group in view of the reported equivocal response to mechanical dilatation and pre-disposition of children to respiratory complications. The results of surgery were satisfactory. ImagesFig. 1Fig. 2Fig. 3Fig. 4Fig. 5Fig. 6Fig. 7Fig. 8 PMID:5790932

Singh, Harjit; Sethi, R. S.; Gupta, H. L.; Khetarpal, S. K.

1969-01-01

415

"Caged calcium" in Aplysia pacemaker neurons. Characterization of calcium-activated potassium and nonspecific cation currents  

PubMed Central

We have studied calcium-activated potassium current, IK(Ca), and calcium-activated nonspecific cation current, INS(Ca), in Aplysia bursting pacemaker neurons, using photolysis of a calcium chelator (nitr-5 or nitr-7) to release "caged calcium" intracellularly. A computer model of nitr photolysis, multiple buffer equilibration, and active calcium extrusion was developed to predict volume-average and front-surface calcium concentration transients. Changes in arsenazo III absorbance were used to measure calcium concentration changes caused by nitr photolysis in microcuvettes. Our model predicted the calcium increments caused by successive flashes, and their dependence on calcium loading, nitr concentration, and light intensity. Flashes also triggered the predicted calcium concentration jumps in neurons filled with nitr-arsenazo III mixtures. In physiological experiments, calcium- activated currents were recorded under voltage clamp in response to flashes of different intensity. Both IK(Ca) and INS(Ca) depended linearly without saturation upon calcium concentration jumps of 0.1-20 microM. Peak membrane currents in neurons exposed to repeated flashes first increased and then declined much like the arsenazo III absorbance changes in vitro, which also indicates a first-order calcium activation. Each flash-evoked current rose rapidly to a peak and decayed to half in 3-12 s. Our model mimicked this behavior when it included diffusion of calcium and nitr perpendicular to the surface of the neuron facing the flashlamp. Na/Ca exchange extruding about 1 pmol of calcium per square centimeter per second per micromolar free calcium appeared to speed the decline of calcium-activated membrane currents. Over a range of different membrane potentials, IK(Ca) and INS(Ca) decayed at similar rates, indicating similar calcium stoichiometries independent of voltage. IK(Ca), but not INS(Ca), relaxes exponentially to a different level when the voltage is suddenly changed. We have estimated voltage-dependent rate constants for a one-step first-order reaction scheme of the activation of IK(Ca) by calcium. After a depolarizing pulse, INS(Ca) decays at a rate that is well predicted by a model of diffusion of calcium away from the inner membrane surface after it has entered the cell, with active extrusion by surface pumps and uptake into organelles. IK(Ca) decays somewhat faster than INS(Ca) after a depolarization, because of its voltage-dependent relaxation combined with the decay of submembrane calcium. The interplay of these two currents accounts for the calcium-dependent outward-inward tail current sequence after a depolarization, and the corresponding afterpotentials after a burst PMID:2504882

1989-01-01