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  1. Article ; Online: Evaluation of a novel PVC and PAC detection algorithm in an implantable cardiac monitor for longitudinal risk monitoring.

    Marmerstein, Joseph / Reddy, Ravi / Whittington, R Hollis / Dukes, Jonathan

    Heart rhythm O2

    2023  Volume 4, Issue 9, Page(s) 592–596

    Language English
    Publishing date 2023-08-27
    Publishing country United States
    Document type Journal Article
    ISSN 2666-5018
    ISSN (online) 2666-5018
    DOI 10.1016/j.hroo.2023.06.001
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article: Temperature monitoring with an implantable loop recorder in a patient with presumed COVID-19.

    Whittington, R Hollis / Muessig, Dirk / Reddy, Ravi / Mohammad, Asad / Mitchell, Kevin / Brumbaugh, Jon / Mehta, Davendra / Hayes, David

    HeartRhythm case reports

    2020  Volume 6, Issue 8, Page(s) 477–481

    Keywords covid19
    Language English
    Publishing date 2020-06-05
    Publishing country United States
    Document type Case Reports
    ZDB-ID 2834871-0
    ISSN 2214-0271
    ISSN 2214-0271
    DOI 10.1016/j.hrcr.2020.05.024
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Temperature Monitoring with an Implantable Loop Recorder in a Patient with Presumed COVID-19

    Whittington, R. Hollis / Muessig, Dirk / Reddy, Ravi / Mohammad, Asad / Mitchell, Kevin / Brumbaugh, Jon / Hayes, David

    HeartRhythm Case Rep

    Keywords covid19
    Publisher Elsevier; PMC; WHO
    Document type Article ; Online
    Note WHO #Covidence: #548704
    DOI 10.1016/j.hrcr.2020.05.024
    Database COVID19

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  4. Article: Temperature monitoring with an implantable loop recorder in a patient with presumed COVID-19

    Whittington, R Hollis / Muessig, Dirk / Reddy, Ravi / Mohammad, Asad / Mitchell, Kevin / Brumbaugh, Jon / Mehta, Davendra / Hayes, David

    HeartRhythm Case Rep

    Keywords covid19
    Publisher WHO
    Document type Article
    Note WHO #Covidence: #548704
    Database COVID19

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  5. Article ; Online: Temperature monitoring with an implantable loop recorder in a patient with presumed COVID-19

    Whittington, R. Hollis / Muessig, Dirk / Reddy, Ravi / Mohammad, Asad / Mitchell, Kevin / Brumbaugh, Jon / Mehta, Davendra / Hayes, David

    HeartRhythm Case Reports

    2020  Volume 6, Issue 8, Page(s) 477–481

    Keywords Cardiology and Cardiovascular Medicine ; covid19
    Language English
    Publisher Elsevier BV
    Publishing country us
    Document type Article ; Online
    ZDB-ID 2834871-0
    ISSN 2214-0271
    ISSN 2214-0271
    DOI 10.1016/j.hrcr.2020.05.024
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article ; Online: Temperature monitoring with an implantable loop recorder in a patient with presumed COVID-19

    R. Hollis Whittington, PhD / Dirk Muessig, PhD / Ravi Reddy, PhD / Asad Mohammad, MD / Kevin Mitchell, BS / Jon Brumbaugh / Davendra Mehta, MD, PhD, FHRS / David Hayes, MD, FHRS

    HeartRhythm Case Reports, Vol 6, Iss 8, Pp 477-

    2020  Volume 481

    Keywords BIOMONITOR ; COVID ; Fever ; Implantable cardiac monitor ; Implantable loop recorder (ILR) ; Remote monitoring ; Diseases of the circulatory (Cardiovascular) system ; RC666-701 ; covid19
    Language English
    Publishing date 2020-08-01T00:00:00Z
    Publisher Elsevier
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Article: A discrete-time control algorithm applied to closed-loop pacing of HL-1 cardiomyocytes.

    Whittington, R Hollis / Kovacs, Gregory T A

    IEEE transactions on bio-medical engineering

    2008  Volume 55, Issue 1, Page(s) 21–30

    Abstract: Electrical stimulation represents a useful tool for electrophysiologic investigation of electrically excitable cells such as cardiomyocytes. The stimulation threshold and electrophysiologic response to precisely timed pulses yields valuable information ... ...

    Abstract Electrical stimulation represents a useful tool for electrophysiologic investigation of electrically excitable cells such as cardiomyocytes. The stimulation threshold and electrophysiologic response to precisely timed pulses yields valuable information regarding physiologic processes. However, determining these parameters accurately, while simultaneously resolving time-dependent or transient effects has been difficult or impossible with previous methods. This paper presents a discrete-time algorithmic controller used for closed-loop electrical stimulation of HL-1 clonal cardiomyocytes cultured on, and stimulated using, a planar microelectrode array. We introduce the temporal error-controlled algorithm (TECA), that is well-suited to control using capture fraction, a low data rate, highly quantized feedback parameter describing stimulation efficacy. HL-1 cardiomyocytes were electrically stimulated and resulting parameters were used to develop a representative model of partial capture, enabling extensive analysis of the algorithm. The performance of this approach is compared via computer simulation to a previously introduced conditional convergence algorithm to quantify its performance and relative advantages. Operation of the TECA is demonstrated by tracking the real-time biological response of stimulation threshold to a rapid increase in extracellular potassium concentration in four independent cell cultures. This work enables the use of stimulation threshold as a real-time, continuously monitored parameter with considerable utility in cardiac pharmacology, electrophysiology, and cell-based biosensing.
    MeSH term(s) Action Potentials/physiology ; Algorithms ; Animals ; Biological Clocks/physiology ; Cardiac Pacing, Artificial/methods ; Cell Line ; Feedback ; Heart Conduction System/physiology ; Mice ; Myocytes, Cardiac/physiology ; Signal Processing, Computer-Assisted ; Therapy, Computer-Assisted/instrumentation ; Therapy, Computer-Assisted/methods
    Language English
    Publishing date 2008-01
    Publishing country United States
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 160429-6
    ISSN 1558-2531 ; 0018-9294
    ISSN (online) 1558-2531
    ISSN 0018-9294
    DOI 10.1109/TBME.2007.910641
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

    Zs.A 425: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (1.OG)
    ab Jg. 2022: Lesesaal (EG)

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  8. Article: A closed-loop electrical stimulation system for cardiac cell cultures.

    Whittington, R Hollis / Giovangrandi, Laurent / Kovacs, Gregory T A

    IEEE transactions on bio-medical engineering

    2005  Volume 52, Issue 7, Page(s) 1261–1270

    Abstract: An integrated electrical stimulation and recording system was designed for closed-loop control and analysis of cardiac cultures on planar microelectrode arrays. Stimulated action potentials from HL-1 clonal myocyte cultures were digitized, stimulation ... ...

    Abstract An integrated electrical stimulation and recording system was designed for closed-loop control and analysis of cardiac cultures on planar microelectrode arrays. Stimulated action potentials from HL-1 clonal myocyte cultures were digitized, stimulation artifacts were removed using nulling and filtering methods, and analysis was performed to determine stimulation efficacy in real time. Results of this analysis were used to determine future stimulation waveform parameters such as polarity, amplitude, pulse duration, and rate or pattern. Algorithms were designed utilizing real-time analysis and control to maintain a desired electrophysiological response of the culture, such as an arbitrary capture fraction value. This paper presents the hardware and software design of the stimulus pulse circuitry, artifact extraction, analysis, and control components of the system. Applications of this technology include the study of cardiac cell physiology, improving the speed and accuracy of traditional open-loop stimulation protocols, pharmacological screening, and improving the performance of biosensors based on sensing electrical activity in cardiac cultures.
    MeSH term(s) Action Potentials/physiology ; Animals ; Cardiac Pacing, Artificial/methods ; Cell Culture Techniques/instrumentation ; Cell Culture Techniques/methods ; Cells, Cultured ; Electric Stimulation/instrumentation ; Electric Stimulation/methods ; Electrocardiography/instrumentation ; Electrocardiography/methods ; Equipment Design ; Equipment Failure Analysis ; Feedback/physiology ; Mice ; Myocardial Contraction/physiology ; Myocytes, Cardiac/physiology ; Pacemaker, Artificial
    Language English
    Publishing date 2005-07
    Publishing country United States
    Document type Evaluation Studies ; Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 160429-6
    ISSN 1558-2531 ; 0018-9294
    ISSN (online) 1558-2531
    ISSN 0018-9294
    DOI 10.1109/TBME.2005.847539
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

    Zs.A 425: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (1.OG)
    ab Jg. 2022: Lesesaal (EG)

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  9. Article: Cardiac differentiation of embryonic stem cells with point-source electrical stimulation.

    Chen, Michael Q / Xie, Xiaoyan / Hollis Whittington, R / Kovacs, Gregory T A / Wu, Joseph C / Giovangrandi, Laurent

    Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference

    2009  Volume 2008, Page(s) 1729–1732

    Abstract: The use of pluripotent stem cells as a means to repair damaged heart tissue has recently emerged as a promising, yet controversial therapy. Despite the different approaches and the variety of cell types used, many of these procedures have been met with ... ...

    Abstract The use of pluripotent stem cells as a means to repair damaged heart tissue has recently emerged as a promising, yet controversial therapy. Despite the different approaches and the variety of cell types used, many of these procedures have been met with mixed success. The lack of understanding of the differentiation and integration process, notably with respect to electrical signaling, significantly hampers the development of these therapies. A system was thus developed allowing the use of point source electrical stimulation on embryonic stem (ES) cells to study the effect of physiologically-relevant electrical stimulus. When modulating the amplitude of the stimulus over various differentiation stages of embryonic stem cells, differences in the proportions of cardiomyocytes to embryonic stem cells were observed through quantitative PCR. The use of this technique might have larger applications in understanding molecular pathways towards the regeneration process.
    MeSH term(s) Animals ; Biomedical Engineering ; Cardiac Myosins/genetics ; Cell Differentiation ; Cell Line ; Electric Stimulation/instrumentation ; Electric Stimulation/methods ; Embryonic Stem Cells/cytology ; Embryonic Stem Cells/metabolism ; Gene Expression Regulation, Developmental ; Homeodomain Proteins/genetics ; Mice ; Microelectrodes ; Myocytes, Cardiac/cytology ; Myocytes, Cardiac/metabolism ; Nanog Homeobox Protein ; Pluripotent Stem Cells/cytology ; Pluripotent Stem Cells/metabolism ; Polymerase Chain Reaction ; Troponin T/genetics
    Chemical Substances Homeodomain Proteins ; Nanog Homeobox Protein ; Nanog protein, mouse ; Troponin T ; Cardiac Myosins (EC 3.6.1.-)
    Language English
    Publishing date 2009-01-21
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ISSN 2375-7477
    ISSN 2375-7477
    DOI 10.1109/IEMBS.2008.4649510
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article: Temporal resolution of stimulation threshold: a tool for electrophysiologic analysis.

    Whittington, R Hollis / Chen, Michael Q / Giovangrandi, Laurent / Kovacs, Gregory T A

    Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference

    2006  Volume 2006, Page(s) 3891–3894

    Abstract: Electrical stimulation of cardiac cultures with closed-loop control permits the determination of threshold in real time. The temporal response of stimulation threshold and underlying cell membrane excitability is valuable information for understanding ... ...

    Abstract Electrical stimulation of cardiac cultures with closed-loop control permits the determination of threshold in real time. The temporal response of stimulation threshold and underlying cell membrane excitability is valuable information for understanding the complex electrophysiologic processes within cardiac cells and can aid in understanding the mechanisms and effects of pharmaceuticals or other stimuli. This work presents the temporal response of stimulation threshold measured using HL-1 cardiac myocytes when exposed to changes in temperature and extracellular potassium concentration. These changes mimic systemic alteration of excitability and conditions that can result from ischemia in the heart. The results demonstrate the efficacy of stimulation threshold as a physiologic indicator and illustrate transient effects with both fast and slow time constants that can be resolved using a system that determines stimulation threshold in real time.
    MeSH term(s) Animals ; Cell Culture Techniques ; Electric Stimulation/methods ; Electrophysiology/methods ; Heart/physiology ; Heart/physiopathology ; Heart Atria ; Humans ; Kinetics ; Mice ; Microelectrodes ; Myocytes, Cardiac/physiology
    Language English
    Publishing date 2006-06-21
    Publishing country United States
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 2091094-0
    ISSN 1558-4615 ; 1557-170X ; 1094-687X
    ISSN (online) 1558-4615
    ISSN 1557-170X ; 1094-687X
    DOI 10.1109/IEMBS.2006.259332
    Database MEDical Literature Analysis and Retrieval System OnLINE

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