Scholars@Duke
Roger C. Barr

Roger C. Barr

Professor Emeritus of Biomedical Engineering
Biomedical Engineering
roger.barr@duke.edu
Box 90281, Durham, NC 27708-0281
255 Hudson Annex, Durham, NC 27708

Selected Publications

Robust Prediction Of Treatment Times In Concurrent Patient Care.

Journal Article Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference · July 2018 Outpatient centers comprised of many concurrent clinics increasingly see higher patient volumes. In these centers, decisions to improve clinic flow must account for the high degree of interdependence when critical personnel or equipment is shared between c ... Full text Cite

Design of an Interactive Simulation Environment for Arrays of Cardiac Cells.

Journal Article Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference · July 2018 The electrical activity of cardiac cells is complex and their collective action difficult to visualize. Understanding what is happening, overall and cell by cell, requires detailed simulation. Here the design of such a simulation is defined by a list of re ... Full text Cite

Bioelectricity

Chapter · April 19, 2016 Cite

Sensor spacing affects the tissue impedance spectra of rabbit ventricular epicardium.

Journal Article American journal of physiology. Heart and circulatory physiology · June 2014 This study was designed to test the hypothesis that a complex composite impedance spectra develops when stimulation and recording of cardiac muscle with sufficiently fine spatial resolution in a four-electrode configuration is used. With traditional (milli ... Full text Cite

Bioelectricity-AQA, one of the first MOOC courses in engineering.

Conference Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference · January 2014 Bioelectricity-AQA was one of the first massively open online courses in engineering, having been given the first time via Coursera starting in September, 2012. This report provides some detail on its background, presentation, enrollment, and lessons learn ... Full text Cite

A structural framework for interpretation of four-electrode microimpedance spectra in cardiac tissue.

Conference Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference · January 2014 Renewed interest in the four-electrode method for identification of passive electrical properties in cardiac tissue has been sparked by a recognition that measurements made with sensors in close proximity are frequency dependent. Therefore, resolution of f ... Full text Cite

Basic Electrophysiology

Chapter · January 1, 2014 Benjamin Franklin pointed out the boundless possibilities for error allowed by human imagination. Luigi Galvani was nonetheless correct in his most important conclusions that the underlying mechanism of the transmission of information by nerves is electric ... Full text Cite

Bioelectric Phenomena

Book · January 1, 2014 Cite

A new approach for resolution of complex tissue impedance spectra in hearts.

Journal Article IEEE transactions on bio-medical engineering · September 2013 This study was designed to test the feasibility of using sinusoidal approximation in combination with a new instrumentation approach to resolve complex impedance (uCI) spectra from heart preparations. To assess that feasibility, we applied stimuli in the 1 ... Full text Cite

A biophysical model for cardiac microimpedance measurements.

Journal Article American journal of physiology. Heart and circulatory physiology · June 2010 Alterations to cell-to-cell electrical conductance and to the structural arrangement of the collagen network in cardiac tissue are recognized contributors to arrhythmia development, yet no present method allows direct in vivo measurements of these conducta ... Full text Cite

Bayesian quantitative electrophysiology and its multiple applications in bioengineering.

Journal Article IEEE reviews in biomedical engineering · January 2010 Bayesian interpretation of observations began in the early 1700s, and scientific electrophysiology began in the late 1700s. For two centuries these two fields developed mostly separately. In part that was because quantitative Bayesian interpretation, in pr ... Full text Cite

A biophysical model for cardiac microimpedance

Journal Article American Journal of Physiology, Heart · May 1, 2009 Cite

Bayesian analysis of fiber impedance measurements.

Journal Article Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference · December 1, 2007 The resistivities of microscale components of excitable tissue include the longitudinal intracellular and interstitial resistivities and the membrane resistivity. Measurements of these tissue micro impedances have rarely been obtained, mainly because of th ... Cite

Bioelectricity: A quantitative approach

Journal Article Bioelectricity: A Quantitative Approach · December 1, 2007 Bioelectricity: A Quantitative Approach Robert Plonsey and Roger C. Barr The study of electrophysiology has progressed rapidly because of the precise, delicate, and ingenious experimental studies of many investigators. The field has also made great strides ... Full text Cite

Electric fields around and within single cells during electroporation-a model study.

Journal Article Annals of biomedical engineering · July 2007 One of the key issues in electric field-mediated molecular delivery into cells is how the intracellular field is altered by electroporation. Therefore, we simulated the electric field in both the extracellular and intracellular domains of spherical cells d ... Full text Cite

To the Editor-Response

Journal Article Heart Rhythm · July 1, 2007 Full text Cite

A computer model of electrical stimulation of peripheral nerves in regional anesthesia.

Journal Article Anesthesiology · February 2007 BACKGROUND: Nerve stimulation for regional anesthesia can be modeled mathematically. The authors present a mathematical framework to model the underlying electrophysiology, the development of software to implement that framework, and examples of simulation ... Full text Link to item Cite

Mechanism of origin of conduction disturbances in aging human atrial bundles: experimental and model study.

Journal Article Heart Rhythm · February 2007 BACKGROUND: Aging is associated with a significant increase in atrial tachyarrhythmias, especially atrial fibrillation. A macroscopic repolarization gradient created artificially by a stimulus at one site before a premature stimulus from a second site is w ... Full text Link to item Cite

Bayesian analysis of fiber impedance measurements.

Journal Article Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference · January 2007 The resistivities of microscale components of excitable tissue include the longitudinal intracellular and interstitial resistivities and the membrane resistivity. Measurements of these tissue micro impedances have rarely been obtained, mainly because of th ... Full text Cite

Bayesian analysis of fiber impedance measurements.

Journal Article Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference · 2007 Cite

Electric fields in tumors exposed to external voltage sources: implication for electric field-mediated drug and gene delivery.

Journal Article Annals of biomedical engineering · October 2006 The intratumoral field, which determines the efficiency of electric field-mediated drug and gene delivery, can differ significantly from the applied field. Therefore, we investigated the distribution of the electric field in mouse tumors and tissue phantom ... Full text Cite

Cardiac microimpedance measurement in two-dimensional models using multisite interstitial stimulation.

Journal Article American journal of physiology. Heart and circulatory physiology · May 2006 We analyzed central interstitial potential differences during multisite stimulation to assess the feasibility of using those recordings to measure cardiac microimpedances in multidimensional preparations. Because interstitial current injected and removed u ... Full text Cite

Multisite interstitial stimulation for cardiac micro-impedance measurements.

Journal Article Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference · 2006 On theoretical grounds, interstitial current injected and removed using electrodes in close proximity does not cross the membrane, while equilibration of intracellular and interstitial potentials occurs distant from electrodes widely separated. Multisite i ... Cite

Multisite interstitial stimulation for cardiac micro-impedance measurements.

Journal Article Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference · January 2006 On theoretical grounds, interstitial current injected and removed using electrodes in close proximity does not cross the membrane, while equilibration of intracellular and interstitial potentials occurs distant from electrodes widely separated. Multisite i ... Full text Cite

The perplexing complexity of cardiac arrhythmias: beyond electrical remodeling.

Journal Article Heart rhythm · June 2005 Cardiac arrhythmias continue to pose a major medical challenge and significant public health burden. Atrial fibrillation, the most prevalent arrhythmia, affects more than two million Americans annually and is associated with a twofold increase in mortality ... Full text Cite

Feasibility of cardiac microimpedance measurement using multisite interstitial stimulation.

Journal Article American journal of physiology. Heart and circulatory physiology · December 2004 This study was designed to test the hypothesis that analyses of central interstitial potential differences recorded during multisite stimulation with a set of interstitial electrodes provide sufficient data for accurate measurement of cardiac microimpedanc ... Full text Cite

The state of the society

Journal Article IEEE Engineering in Medicine and Biology Magazine · November 1, 2004 Full text Cite

Cell size and communication: role in structural and electrical development and remodeling of the heart.

Journal Article Heart Rhythm · October 2004 With the advent of new information about alterations of cardiac gap junctions in disease conditions associated with arrhythmias, there have been major advances in the genetic and metabolic manipulation of gap junctions. In contrast, in naturally occurring ... Full text Link to item Cite

Electric fields within cells as a function of membrane resistivity--a model study.

Journal Article IEEE transactions on nanobioscience · September 2004 Externally applied electric fields play an important role in many therapeutic modalities, but the fields they produce inside cells remain largely unknown. This study makes use of a three-dimensional model to determine the electric field that exists in the ... Full text Cite

The Disney story.

Journal Article IEEE engineering in medicine and biology magazine : the quarterly magazine of the Engineering in Medicine & Biology Society · September 2004 Full text Cite

Rich before old?

Journal Article IEEE engineering in medicine and biology magazine : the quarterly magazine of the Engineering in Medicine & Biology Society · July 2004 Full text Cite

The attention economy and the EMBS.

Journal Article IEEE engineering in medicine and biology magazine : the quarterly magazine of the Engineering in Medicine & Biology Society · May 2004 Cite

Field stimulation of 2-D sheets of excitable tissue.

Journal Article IEEE transactions on bio-medical engineering · March 2004 This paper develops equations for the transmembrane potentials (Vm) that occur in two-dimensional (2-D) sheets of tissue in response to field stimulation from an electrode near but not on the surface of the tissue. Comparison of results with those for one ... Full text Cite

EMBS international

Journal Article IEEE Engineering in Medicine and Biology Magazine · March 1, 2004 Full text Cite

Design of Electrode Systems for Measuring Cardiac Micro-Impedances Using Optical Sensors

Journal Article Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings · December 1, 2003 The cardiac electrical substrate is a challenge to direct measurement of its properties. Optical technology together with the capability to fabricate small electrodes at close spacings opens new possibilities. Here those possibilities are explored from a t ... Cite

A Possible EMB Award Recognizing Excellent Research by Graduate Students Published in EMB Journals

Journal Article Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings · December 1, 2003 The criteria for a hypothetical award for BME students who publish work in an EMB journal are discussed. The recognition of accomplishment is a core function of a professional society and this award is proposed to recognize the achievement and contribution ... Cite

Interactions between extracellular stimuli and excitation waves in an atrial reentrant loop.

Journal Article Journal of cardiovascular electrophysiology · October 2003 UnlabelledExtracellular Stimuli in an Atrial Reentrant Loop.IntroductionThe interactions between extracellular stimuli and excitation waves propagating in a reentrant loop are a complex function of stimulus parameters, structural properti ... Full text Cite

Electrode systems for measuring cardiac impedances using optical transmembrane potential sensors and interstitial electrodes--theoretical design.

Journal Article IEEE transactions on bio-medical engineering · August 2003 The cardiac electrical substrate is a challenge to direct measurement of its properties. Optical technology together with the capability to fabricate small electrodes at close spacings opens new possibilities. Here, those possibilities are explored from a ... Full text Cite

Membrane current from transmembrane potentials in complex core-conductor models

Journal Article IEEE Trans. Biomed. Eng. (USA) · 2003 Core-conductor models, used to integrate the behavior of the longitudinal currents with the distributed voltages of electrically active tissue, have evolved for over a century. A critical step in the use of such models is the computation of membrane curren ... Full text Link to item Cite

Electromobility of plasmid DNA in tumor tissues during electric field-mediated gene delivery.

Journal Article Gene Ther · October 2002 Interstitial transport is a crucial step in plasmid DNA-based gene therapy. However, interstitial diffusion of large nucleic acids is prohibitively slow. Therefore, we proposed to facilitate interstitial transport of DNA via pulsed electric fields. To test ... Full text Link to item Cite

Termination of reentrant propagation by a single extracellular stimulus in an atrial ring model

Journal Article Annual Reports of the Research Reactor Institute, Kyoto University · December 1, 2001 Cardiac reentry, the underlying mechanism of both tachycardia and fibrillation, is often terminated clinically with extracellular stimuli. We developed a one-dimensional mathematical model to find the probability that a short, randomly-timed extracellular ... Cite

The forward and inverse problems: what are they, why are they important, and where do we stand?

Journal Article Journal of cardiovascular electrophysiology · February 2001 Full text Cite

Changes in anisotropic conduction caused by remodeling cell size and the cellular distribution of gap junctions and Na(+) channels.

Journal Article J Electrocardiol · 2001 Because gene therapy presents a new frontier in the treatment of arrhythmias, it has become important to know how manipulation of the cellular distribution of proteins changes electrical events within individual cells, and whether these cellular changes af ... Full text Link to item Cite

Mobility of plasmid DNA subject to pulsed electric fields

Journal Article Annals of Biomedical Engineering · December 1, 2000 The mobility of plasmid DNA in high amplitude/low duration electric fields was assessed. The influences of pulse amplitude, pulse duration and agarose gel concentration on mobility were compared. Movement of plasmid DNA in an electroporation setting was in ... Cite

Electrophysiological effects of remodeling cardiac gap junctions and cell size: experimental and model studies of normal cardiac growth.

Journal Article Circulation research · February 2000 The increased incidence of arrhythmias in structural heart disease is accompanied by remodeling of the cellular distribution of gap junctions to a diffuse pattern like that of neonatal cardiomyocytes. Accordingly, it has become important to know how remode ... Full text Cite

Extracellular discontinuities in cardiac muscle: evidence for capillary effects on the action potential foot.

Journal Article Circulation research · November 1998 It has become of fundamental importance to understand variations in the shape of the upstroke of the action potential in order to identify structural loading effects. One component of this goal is a detailed experimental analysis of the time course of the ... Full text Cite

Electric field stimulation of excitable tissue.

Journal Article IEEE engineering in medicine and biology magazine : the quarterly magazine of the Engineering in Medicine & Biology Society · September 1998 Full text Cite

Subthreshold electric field stimulation of excitable tissue

Journal Article Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings · December 1, 1997 This paper reviews the conditions under which a single-fiber membrane can be considered to be linear and at steady-state. These properties are useful in evaluating the response of tissue to stimulation, especially in predicting values of the transmembrane ... Cite

Special Issue on Electrical Therapy of Cardiac Arrhythmias

Journal Article Proceedings of the IEEE · January 1, 1996 Full text Cite

Threshold estimation with field stimulation [transmembrane potentials]

Journal Article Med. Biol. Eng. Comput. (UK) · 1996 The central focus of this report is on the evolution of transmembrane potentials following initiation of a point-source field stimulus, particularly when the stimulus is short and the stimulating electrode is close to the responding membrane. A central que ... Cite

Electric field stimulation of cardiac tissue

Journal Article Med. Biol. Eng. Comput. (UK) · 1996 Considers several simple models for the simulation of cardiac fiber stimulation by means of an applied electric field. A particular goal is the determination of conditions under which a steady-state passive membrane model can be utilized in simulation stud ... Cite

Threshold variability in fibers with field stimulation of excitable membranes.

Journal Article IEEE transactions on bio-medical engineering · December 1995 The central focus of this report is the evolution of transmembrane potentials following initiation of a point-source field stimulus, particularly when the stimulus is short and the stimulating electrode is close to the fiber. The transmembrane voltage thre ... Full text Cite

Sustained reentrant propagation in loops of decoupled cardiac cells

Journal Article Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings · December 1, 1995 Simulations were designed to identify the minimum number of cardiac cells that sustained propagation. Cells were connected as a loop with elevated junction resistances. The decrease in the spatial extent of the action potential associated with increasing t ... Cite

Repolarizing stimuli followed by calcium transmembrane currents

Journal Article Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings · December 1, 1995 Repolarizing stimuli applied during the plateau phase of a cardiac action potential do not always cause the membrane to return to a resting state Instead, the repolarizing stimulus may be followed immediately by a subsequent action potential. The subsequen ... Cite

Electric field stimulation of excitable tissue.

Journal Article IEEE transactions on bio-medical engineering · April 1995 This paper examines the transmembrane voltage response of an unmyelinated fiber to a stimulating electric field from a point current source. For subthreshold conditions, analytic expressions for the transmembrane potential, vm, are developed that include t ... Full text Cite

Model of sustained propagation in a 20-cell ring of Purkinje tissue

Journal Article Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings · December 1, 1994 Sustained and stable propagation was simulated in a ring of 20 cardiac cells with Di Francesco-Noble membrane kinetics and connected with elevated junction resistances. The action potential propagated around the ring at least three times with no noticeable ... Cite

Electrocardiographic inverse solution for ectopic origin of excitation in two-dimensional propagation model.

Journal Article Medical & biological engineering & computing · July 1994 Inverse calculations were examined that sought the origin of a cardiac ectopic excitation sequence. Cardiac anatomy and its geometric relationships to sites on the body surface were adapted from human cross-sectional images to form a two-dimensional model, ... Full text Cite

Faster simulations of action potential propagation using the newton method

Journal Article Proceedings of the Annual Conference on Engineering in Medicine and Biology · December 1, 1993 A system of differential equations establishing a two-parallel-fiber geometry with Hodgkin-Huxley membrane properties was integrated with the trapezoidal rule, an implicit integration scheme. The resulting nonlinear system of equations was restated in a fo ... Cite

Unidirectional block in a computer model of partially coupled segments of cardiac Purkinje tissue.

Journal Article Annals of biomedical engineering · November 1993 The initiation of a reentrant circuit requires a zone of slow conduction and a zone of unidirectional block. This study used computer model conditions under which partial coupling between segments of cardiac Purkinje tissue resulted in unidirectional block ... Full text Cite

Reflection after delayed excitation in a computer model of a single fiber.

Journal Article Circulation research · August 1992 Reflection (reflected reentry) is a case of reentry in a one-dimensional structure, divided into proximal and distal segments, in which tissue excited by a wave front propagating in a forward direction is reexcited by electrical activity coming backward fr ... Full text Cite

Propagation model using the DiFrancesco-Noble equations. Comparison to reported experimental results.

Journal Article Medical & biological engineering & computing · May 1992 Propagation, re-entry and the effects of stimuli within the conduction system can be studied effectively with computer models when the pertinent membrane properties can be represented accurately in mathematical form. To date, no membrane models have been s ... Full text Cite

Electrophysiological interaction through the interstitial space between adjacent unmyelinated parallel fibers.

Journal Article Biophysical journal · May 1992 The influence of interstitial or extracellular potentials on propagation usually has been ignored, often through assuming these potentials to be insignificantly different from zero, presumably because both measurements and calculations become much more com ... Full text Cite

Implementation, performance and characterization of the DiFrancesco-Noble model

Conference Proceedings - Computers in Cardiology, CIC 1992 · January 1, 1992 The authors describe their experience in the implementation and the use of the DiFrancesco-Noble model. Clarifying references for the equations are given as well as a way to implement the equations in a propagation model. An estimate of the number of float ... Full text Cite

A possible subcellular structure based on the macroscopic cardiac source.

Journal Article Journal of electrocardiology · January 1992 Full text Cite

Propagation under the influence of interstitial potentials

Conference Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS · January 1, 1992 Interactions between two electrically active fibers were simulated. The fibers were close together and within a restricted volume, so that significant extracellular (interstitial) as well as transmembrane potentials were present, but the fibers were not ot ... Full text Cite

Refractory period in the DiFrancesco-Noble model for Purkinje fibers

Journal Article Proceedings of the Annual Conference on Engineering in Medicine and Biology · December 1, 1991 An investigation was conducted into the refractory period of the DiFrancesco-Noble (DN) membrane model for Purkinje fibers. The results show that the DN model reproduces refractory period properties of real tissue like: supernormality, supernormal conducti ... Cite

Distinguishing ectopic sites in the canine heart by means of body surface waveforms

Journal Article Proceedings of the Annual Conference on Engineering in Medicine and Biology · December 1, 1991 Experimental data are presented for distinguishing sites of origin of ventricular excitation sequences using a single body surface waveform. Waveforms from different ectopic regions of a canine heart were compared. When comparing waveforms, all possible ti ... Cite

Computer simulations of activation in an anatomically based model of the human ventricular conduction system.

Journal Article IEEE transactions on bio-medical engineering · October 1991 Simulations of the electrical activity during excitation were performed in an anatomically based model of the human ventricular conduction system. Each of the 33,000 elements of this model represented a unit bundle of Purkinje or atrioventricular nodal tis ... Full text Cite

One-dimensional model of cardiac defibrillation.

Journal Article Medical & biological engineering & computing · September 1991 The response of a single strand of cardiac cells to a uniform defibrillatory shock assuming steady-state linear conditions is examined. It is argued that the effect of this current is quantitatively described by the induced transmembrane potential even und ... Full text Cite

The construction of an anatomically based model of the human ventricular conduction system.

Journal Article IEEE transactions on bio-medical engineering · December 1990 The ventricular conduction system is a complicated network of specialized muscle cells responsible for the transmission of electrical activity between the atria and the ventricles of the human heart. It has been the focus of numerous electrical and anatomi ... Full text Cite

The design and verification of a VLSI chip for electrocardiogram data compression

Journal Article · December 1, 1990 A VLSI architecture for performing electrocardiogram (ECG) data compression is presented. The goals of the chip are to improve both the speed and the density as compared to an off-the-shelf implementation. The complex control sections of the chip were synt ... Cite

Inverse solutions of ECG using propagation model: A 2-D cross-sectional model

Journal Article Proceedings of the Annual Conference on Engineering in Medicine and Biology · December 1, 1990 An inverse solution for the site of origin of the electrocardiogram (ECG) using a propagation model was examined in a two-dimensional geometry using a propagation model. The model includes elements representing the body surface, cardiac conduction system, ... Cite

Simulation and vertification of a chip architecture for electrocardiogram data compression

Journal Article Modeling and Simulation, Proceedings of the Annual Pittsburgh Conference · December 1, 1990 The simulation and verification of a VLSI chip for real-time compression of electrocardiogram data is presented. We describe a three-tier simulation process, and tell how this approach assisted in the development of the chip. The verification procedure all ... Cite

Transmembrane current model in a stylized form

Journal Article Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings · December 1, 1989 A mathematical model that approximates the propagating transmembrane current is developed. The model gives direct evaluation of the cardiac sources and avoids the singularity at the origin of excitation which was the major problem with the previous tanh ap ... Cite

Computer simulations of excitation in an anatomically based model of the human ventricular conduction system

Journal Article Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings · November 1, 1989 The simulation of excitation in a model whose gross physical characteristics are representative of the human ventricular conduction system is discussed. This objective was realized, and the resultant behavior reproduced the major features of a sequence est ... Cite

VLSI design for fan adaptive sampling

Journal Article Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings · November 1, 1989 A semicustom VLSI chip for real-time adaptive sampling has been designed. The chip executes the fan algorithm at a rate of about 1 μs per sample, an order of magnitude faster than a previous realization using general-purpose signal processing chips. This i ... Cite

Real-time adaptive sampling with the fan algorithm.

Journal Article Medical & biological engineering & computing · November 1988 Full text Cite

Prototype for real-time adaptive sampling using the fan algorithm.

Journal Article Medical & biological engineering & computing · November 1988 Full text Cite

Automated construction of simulation models for a study of the electrical activity in the ventricular conduction system

Journal Article IEEE/Engineering in Medicine and Biology Society Annual Conference · November 1, 1988 A procedure for the automated construction of simulation models of the ventricular conduction system from limited anatomical data has been developed. A set of points on the endocardial surface is selected as early activation sites, or connections with the ... Cite

Adaptive sampling using adaptive tolerance for mixed rate transmission

Journal Article IEEE/Engineering in Medicine and Biology Society Annual Conference · November 1, 1988 A system for adaptive sampling of biological waveforms has been developed. A significant feature of the design is that samples are selected at variable rates with the fan algorithm, but transmitted to the user at a fixed permanent rate the user specifies. ... Cite

Adaptive sampling of cardiac waveforms.

Journal Article Journal of electrocardiology · January 1988 In recent years cardiac electrocardiograms and electrograms often have been measured using automated sampling systems that record samples periodically, with a fixed sample-to-sample interval. In contrast, adaptive sampling systems envision variable sample- ... Full text Cite

REAL-TIME ADAPTIVE SAMPLING WITH THE FAN METHOD.

Journal Article IEEE/Engineering in Medicine and Biology Society Annual Conference · December 1, 1987 OFfline analyses have shown the Fan algorithm to be an effective method for adaptive sampling of cardiac signals. The feasibility of implementing the Fan in real-time has been evaluated. A prototype has been constructed using the TMS32010 signal processor. ... Cite

INVERSE PROBLEMS BASED ON MEMBRANE PROPAGATION MODELS.

Journal Article IEEE/Engineering in Medicine and Biology Society Annual Conference · December 1, 1987 Studies of forward and inverse relationships in cylindrical strands have mostly analyzed each time instant separately. Here, the whole time sequence involved in a waveform is linked together on the basis of an underlying membrane model. An example shows th ... Cite

Mathematical modeling of electrical activity of the heart.

Journal Article Journal of electrocardiology · July 1987 This paper reviews the literature on mathematical models of cardiac activation and evaluates these approaches against an analytical approach that includes both structure and membrane properties. The advantages and disadvantages of each methodology are desc ... Full text Cite

Adaptive sampling of intracellular and extracellular cardiac potentials with the fan method.

Journal Article Medical & biological engineering & computing · May 1987 Full text Cite

Interstitial potentials and their change with depth into cardiac tissue.

Journal Article Biophysical journal · April 1987 The electrical source strength for an isolated, active, excitable fiber can be taken to be its transmembrane current as an excellent approximation. The transmembrane current can be determined from intracellular potentials only. But for multicellular prepar ... Full text Cite

Body surface mapping for arrhythmias: Discussion

Journal Article Circulation · 1987 Cite

Body surface mapping for arrhythmias: Discussion

Journal Article Circulation · January 1, 1987 Cite

A critique of impedance measurements in cardiac tissue.

Journal Article Annals of biomedical engineering · January 1986 The specific impedance of cardiac tissue cannot be measured directly. Instead, the investigator obtains voltage and current measurements and places them into a model of the tissue's structure to infer the impedances of elements of the model. If the model f ... Full text Cite

INVERSE SOLUTION IN ONE DIMENSION USING A MEMBRANE MODEL.

Journal Article · January 1, 1986 A problem of great interest in electrocardiology is finding excitation sequences within the heart from accessible electrode recordings. The most elementary level of this problem is determining intracellular excitation sequences from extracellular recording ... Cite

IMPEDANCE MEASUREMENTS IN CARDIAC TISSUE.

Journal Article Bioengineering, Proceedings of the Northeast Conference · December 1, 1985 In the measurement of tissue impedance, one normally places a system of electrodes on a sample, introduces a known current and measures resulting voltages, which then serve to determine the impedance through some algorithm. To carry out the last step succe ... Cite

Evaluation of the fan method of adaptive sampling on human electrocardiograms.

Journal Article Medical & biological engineering & computing · September 1985 Full text Cite

Comparison of methods for adaptive sampling of cardiac electrograms and electrocardiograms.

Journal Article Medical & biological engineering & computing · July 1985 Full text Cite

SAPA-2 is the Fan.

Journal Article IEEE transactions on bio-medical engineering · May 1985 Full text Cite

SAPA-2 is the Fan [ECG]

Journal Article IEEE Trans. Biomed. Eng. (USA) · 1985 The algorithm SAPA-2, presented recently (ibid., vol.BME-30, p.723-9, 1983) as a method for representing electrocardiographic waveforms as a series of straight-line segments, is seen as being equivalent to an older algorithm, the Fan ... Cite

Effect of junctional resistance on source-strength in a linear cable.

Journal Article Annals of biomedical engineering · January 1985 This paper studies the relative strength of sources associated with the cell and the junction between cells of an equivalent single cardiac fiber. It is shown that the junctional source is negligible compared to the cellular source. On the other hand, the ... Full text Cite

COMPARISON OF ADAPTIVE SAMPLING METHODS FOR ELECTROGRAMS AND ELECTROCARDIOGRAMS.

Journal Article IEEE/Engineering in Medicine and Biology Society Annual Conference · December 1, 1984 Numerous redundant samples result from sampling cardiac electrograms (EG) and electrocardiograms (ECG) with high uniform rates, particularly for measurements that include Purkinje deflections. Waveforms measured with five adaptive sampling methods (voltage ... Cite

STUDY OF THE FAN METHOD OF ADAPTIVE SAMPLING FOR HUMAN ECGS.

Journal Article Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings · December 1, 1984 ECGs often are measured by digital sampling at uniform rates. With uniform sampling, no changes in the sampling rate are made in relation to the experimental content of the ECG. This study examined the question of which samples should be selected so that t ... Cite

MOTORIZED FOREARM MODULE FOR PROSTHETIC TERMINAL DEVICES.

Journal Article IEEE/Engineering in Medicine and Biology Society Annual Conference · December 1, 1984 A motorized forearm module has been developed to operate conventional body-powered prosthetic terminal devices for upper extremity amputees unable to successfully operate these devices themselves. The module attaches between the socket portion of the prost ... Cite

Propagation of excitation in idealized anisotropic two-dimensional tissue.

Journal Article Biophysical journal · June 1984 This paper reports on a simulation of propagation for anisotropic two-dimensional cardiac tissue. The tissue structure assumed was that of a Hodgin-Huxley membrane separating inside and outside anisotropic media, obeying Ohm's law in each case. Membrane cu ... Full text Cite

Current flow patterns in two-dimensional anisotropic bisyncytia with normal and extreme conductivities.

Journal Article Biophysical journal · March 1984 Cardiac tissue has been shown to function as an electrical syncytium in both intracellular and extracellular (interstitial) domains. Available experimental evidence and qualitative intuition about the complex anatomical structure support the viewpoint that ... Full text Cite

Finding the site of origin and velocity of propagation in a short one-dimensional strand from two extracellular waveforms

Journal Article IEEE Trans. Biomed. Eng. (USA) · 1984 A method is evaluated for determining the sequence of excitation of cardiac muscles from only two known extracellular waveforms. The approach takes advantage of the entire time course of the observed waveforms, not just their intrinsic deflections. The mos ... Cite

Construction and interpretation of body surface maps.

Journal Article Progress in cardiovascular diseases · July 1983 Full text Cite

Localizing cardiac electrical events from body surface maps.

Journal Article International journal of cardiology · July 1983 Full text Cite

ZERO, FIRST, AND SECOND ORDER ADAPTIVE SAMPLING FROM ECGS.

Journal Article Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings · December 1, 1982 Cite

A voltage-triggered system for adaptive sampling in body surface mapping.

Journal Article IEEE transactions on bio-medical engineering · November 1982 Full text Cite

The four-electrode resistivity technique as applied to cardiac muscle.

Journal Article IEEE transactions on bio-medical engineering · July 1982 Full text Cite

A voltage-triggered system for adaptive sampling in body surface mapping

Journal Article IEEE Trans. Biomed. Eng. (USA) · 1982 Cardiac electrophysiological waveforms are particularly well suited for adaptive sampling since they are periodic and contain some segments of both rapid and slow change. Rather than sampling at a constant rate, adaptive sampling allows the sampling rate t ... Cite

A portable body surface potential mapping system

Journal Article Japanese Heart Journal · January 1, 1982 A portable isopotential surface mapping system was developed to determine if body surface maps can be measured as an integral part of diagnostic studies in acutely ill patients and in those undergoing electrophysiological cardiac catheterization for arrhyt ... Cite

The four-electrode resistivity technique as applied to cardiac muscle

Journal Article Japanese Heart Journal · January 1, 1982 To correctly describe the macroscopic electrical properties of cardiac tissue it is necessary to recognize its bidomain structure. The first part of this presentation describes the bidomain and its governing mathematical equations. The second part is an ap ... Cite

Automated production of contour maps for electrophysiology. III. Construction of contour maps.

Journal Article Computers and biomedical research, an international journal · April 1980 Full text Cite

Accessory atrioventricular pathway in an infant: prediction of location with body surface maps and ablation with cryosurgery.

Journal Article J Pediatr · January 1980 A 10-month-old infant with multiple muscular ventricular septal defects, congestive heart failure, Wolff-Parkinson-White syndrome, and supraventricular tachycardia is presented. The site of ventricular pre-excitation was predicted by analysis of ST-T wave ... Full text Link to item Cite

CONSTRUCTION OF ISOCHRONE OR ISOPOTENTIAL MAPS FOR CARDIAC ELECTROPHYSIOLOGY - A STATEMENT OF THE PROBLEM AND ONE APPROACH TO ITS SOLUTION.

Journal Article Multi-phase Transport: Fundamentals, Reactor Safety, Applications · January 1, 1980 Contour maps showing potential distributions or sequences of times of excitation are used to portray electrical events on surfaces of the body or the heart. Computerized construction of such maps provides a means for many maps of high accuracy to be obtain ... Cite

CONSTRUCTION OF ISOCHRONE OR ISOPOTENTIAL MAPS FOR CARDIAC ELECTROPHYSIOLOGY - A STATEMENT OF THE PROBLEM AND ONE APPROACH TO ITS SOLUTION.

Journal Article Multi-phase Transport: Fundamentals, Reactor Safety, Applications · 1980 Contour maps showing potential distributions or sequences of times of excitation are used to portray electrical events on surfaces of the body or the heart. Computerized construction of such maps provides a means for many maps of high accuracy to be obtain ... Cite

Extracellular potentials related to intracellular action potentials during impulse conduction in anisotropic canine cardiac muscle.

Journal Article Circulation research · August 1979 This paper considers a quantitative description of intracellular and transmembrane currents in anisotropic muscle, with emphasis on the factors that determine the extracellular potentials. Although Vmax of the intracellular action potential had no relation ... Full text Cite

Two-level control of a real-time data acquisition and control system for studying the electrical activity of the heart

Conference Proceedings of the 16th Annual Southeast Regional Conference, ACM-SE 1978 · April 13, 1978 A high speed data acquisition system for experiments investigating the electrical activity of the heart is discussed with emphasis on the method of specifying and controlling the experiment in progress. Provision is made for control by the investigator dur ... Full text Cite

Origin of epicardial ST-T wave potentials in the intact dog.

Journal Article Advances in cardiology · January 1978 Full text Cite

Origin of body surface QRS and T wave potentials from epicardial potential distributions in the intact chimpanzee.

Journal Article Circulation · February 1977 Epicardial and body surface QRS-T wave potential distributions were measured during normal and ectopic sequences in intact chimpanzees. Epicardial potential distributions were used because they provide a comprehensive picture of total cardiac electrical ac ... Full text Cite

Relating epicardial to body surface potential distributions by means of transfer coefficients based on geometry measurements

Journal Article IEEE Trans. Biomed. Eng. (USA) · 1977 Advances in experimental capabilities have made possible the nearly simultaneous measurement of both cardiac epicardial and corresponding body surface potential distributions from in vivo animal preparations using chronically implanted electrodes to keep t ... Cite

Direct and inverse solutions; equivalent cardiac generator models

Journal Article Advances in Cardiology · January 1, 1977 Cite

Surface maps; information content and data reduction; lead systems

Journal Article Advances in Cardiology · January 1, 1977 Cite

Sampling rates required for digital recording of intracellular and extracellular cardiac potentials.

Journal Article Circulation · January 1977 Electrocardiograms and cardiac electrograms now frequently are measured for both clinical and experimental purposes by direct digital sampling, with no recording of the signal in analog form. This study examined the question of what sampling rates were req ... Full text Cite

The design of a real-time computer system for examining the electrical activity of the heart.

Journal Article Computers and biomedical research, an international journal · October 1976 Full text Cite

Origin of epicardial ST-T wave potentials in the intact dog.

Journal Article Circulation research · October 1976 Ventricular repolarization was analyzed by measuring epicardial potential distributions in intact dogs with single or multiple ectopic foci and a minimum at the terminal site(s) of excitation. During the latter half of the T wave the distributions became m ... Full text Cite

Organization of a computer system for measuring the electrical activity of the heart

Conference Proceedings of the 14th Annual Southeast Regional Conference, ACM-SE 1976 · April 22, 1976 We have approached the study of the electrical activity of the heart by separating the work into two distinct phases - data acquisition and data analysis. The data acquisition program monitors the activity of the heart, samples as many as 24 electrodes sim ... Full text Cite

Anaylsis of ventricular activation and repolarization from intramural and epicardial potential distributions for ectopic beats in the intact dog.

Journal Article Circulation research · December 1975 Ventricular activation and repolarization were examined by measuring intramural and epicardial potential distributions during ectopic sequences in intact dogs. Potential distributions were used because they provided a direct measure of all of repolarizatio ... Full text Cite

Ventricular intramural and epicardial potential distributions during ventricular activation and repolarization in the intact dog.

Journal Article Circulation research · August 1975 Ventricular intramural and epicardial potential distributions were measured during normal excitation and repolarization in intact dogs. Potential distributions were chosen because they can be unambiguously measured, are useful in understanding the shapes o ... Full text Cite

Biomac: Block structured programming using PDP‐11 assembler language

Journal Article Software: Practice and Experience · January 1, 1975 Users of small computers must often program in assembler language. Macros are described which assist in the construction of block structured programs in assembler language. The macros are used in practical day‐to‐day programming in a cardiac electrophysiol ... Full text Cite

Spread of excitation from the atrium into thoracic veins in human beings and dogs.

Journal Article The American journal of cardiology · December 1972 Full text Cite

The use of isopotential surface maps in understanding clinical ECGs.

Journal Article American journal of diseases of children (1960) · September 1972 Full text Cite

Selection of the number and positions of measuring locations for electrocardiography.

Journal Article IEEE transactions on bio-medical engineering · March 1971 Full text Cite

Exploratory electrocardiography: use of isopotential surface maps.

Journal Article UCLA forum in medical sciences · January 1970 Cite

Ventricular intracradiac shunting mechanisms in congenital heart disease.

Journal Article UCLA forum in medical sciences · January 1970 Cite

An inverse electrocardiographic solution with an ON-OFF model.

Journal Article IEEE transactions on bio-medical engineering · January 1970 Full text Cite

Computing inverse solutions for an on-off heart model.

Journal Article IEEE transactions on bio-medical engineering · July 1969 Cite

Isopotential surface maps.

Journal Article Annals of internal medicine · May 1969 Full text Cite

Effect of conductivity interfaces in electrocardiography.

Journal Article The Bulletin of mathematical biophysics · December 1968 Full text Cite

Clinical implications of isopotential surface maps.

Journal Article Annals of internal medicine · November 1968 Full text Cite

Effect of conductivity interfaces.

Journal Article The Bulletin of mathematical biophysics · December 1967 Full text Cite

Letter to the editor

Journal Article American Heart Journal · August 1, 1967 Link to item Cite

Body surface isopotential maps in normal children, ages 4 to 14 years.

Journal Article American heart journal · November 1966 Full text Cite

Comparing methods of generating surface potentials.

Journal Article IEEE transactions on bio-medical engineering · October 1966 Cite

Determining surface potentials from current dipoles, with application to electrocardiography.

Journal Article IEEE transactions on bio-medical engineering · April 1966 Full text Cite

Calculation of resistance of threedimensional configurations

Journal Article Proceedings of the IEEE · 1966 Cite

Determining surface potentials from current dipoles, with application to electrocardiography

Journal Article IEEE Transactions on Biomedical Engineering · 1966 Presents a method for determining the potentials over the surface of a three-dimensional volume due to internal current sources. The volume may be inhomogeneous and irregularly shaped. The method for determining the potentials uses N simultaneous equations ... Cite

Comparing methods of generating surface potentials

Journal Article IEEE Transactions on Biomedical Engineering · 1966 Cite

An analysis of transfer coefficients calculated directly from epicardial and body surface potential measurements in the intact dog

Journal Article IEEE Trans. Biomed. Eng. (USA) The study considered the feasibility of obtaining transfer coefficients directly from sequences of epicardial and body surface measurements of ventricular excitation and repolarisation potential distributions, rather than from measurements of the geometry ... Cite