Scholars@Duke
Robert A. Malkin

Robert A. Malkin

Professor of the Practice Emeritus in the Department of Biomedical Engineering
Biomedical Engineering
robert.malkin@duke.edu
Duke Box 90281, 1427 FCIEMAS, Durham, NC 27708-0281
1427 Fitzpatrick Center, Durham, NC 27708

Scholarly Works - Journal articles

Teenagers’ future diabetes risk perception

Journal article World Journal of Biology Pharmacy and Health Sciences · April 30, 2024 Asians are often thought to have a poor ability to predict their future risk of diabetes. We studied perceptions of Type 2 diabetes future risk in middle school and high school students. All students watched two short videos about Body Mass Index ... Full text Cite

Errors in Metered Dose Inhaler Use Amongst Pediatric Asthma Patients.

Journal article Journal of asthma and allergy · January 2023 PurposeThe aim of this paper is to use easily accessible smartphones as a straightforward means for physicians to objectively check Medical Device Inhaler (MDI) technique, without the need for additional devices. Additionally, we seek to assess th ... Full text Cite

HANDLINK: A Dexterous Robotic Hand Exoskeleton controlled by Motor Imagery (MI)

Journal article Journal of Advances in Medicine and Medical Research · December 1, 2022 Introduction: Over 5.6 million stroke survivors in the United States experience hemiparesis of the upper limb. Assistive devices are used to help regain upper limb functionality for affected individuals; however, existing devices are bulky, costly, ... Full text Cite

The Effect of Vaping and Nicotine-containing Liquids to Suppress the Immune System: A Pilot Study

Journal article Journal of Advances in Medicine and Medical Research · December 19, 2021 Aims: We present a pilot study to illustrate how the impact of vaping can be quickly and conclusively documented in a large population and appropriate subpopulations. Methods: It has been predicted that with longer duration and higher frequen ... Full text Cite

Effects of the Pratt pouch model of dispensing nevirapine prophylaxis on HIV exposed infant completion of 6 weeks of prophylaxis in Uganda.

Journal article PloS one · January 2021 IntroductionThe innovative Pratt pouch could optimize dispensing nevirapine prophylaxis to HIV-exposed infants in pre-measured single dose pouches to increase completion of the full 6 week infant nevirapine regimen.Materials and methodsNi ... Full text Open Access Cite

A sustainability evaluation of a biomedical technician training program in Honduras

Journal article Health and Technology · September 1, 2018 Engineering World Health (EWH) developed and executed a unique model to train biomedical technicians (BMET) in Rwanda, Honduras, and Cambodia. This model significantly decreased out-of-service equipment, one to two years after the training’s initiation, wh ... Full text Cite

Problems with systems of medical equipment provision: an evaluation in Honduras, Rwanda and Cambodia identifies opportunities to strengthen healthcare systems

Journal article Health and Technology · May 1, 2018 A substantial amount of equipment is out-of-service in the developing world. Out-of-service equipment limits access to important medical procedures. We measured the amount of out-of-service donated, purchased and loaned medical equipment and documented the ... Full text Cite

Part II: U.S.-Sub-Saharan Africa Educational Partnerships for Medical Device Design.

Journal article Annals of biomedical engineering · November 2017 Full text Cite

Providing Safe and Effective Preventative Antiretroviral Prophylaxis to HIV-exposed Newborns via a Novel Drug Delivery System in Tanzania.

Journal article Pediatr Infect Dis J · September 2016 BACKGROUND: In developing countries, antiretroviral therapy provides life-saving treatment to HIV-positive women and their children before, during and after birth. However, supply chain challenges such as long distances, medication shortages and nonfacilit ... Full text Link to item Cite

The Pratt Pouch Provides a Three-Fold Access Increase to Antiretroviral Medication for Births outside Health Facilities in Southern Zambia.

Journal article The open biomedical engineering journal · January 2016 IntroductionModern day antiretroviral therapy allows HIV+ pregnant women to lower the likelihood of viral transmission to their infants before, during, and after birth from 20-45% to less than 5%. In developing countries, where non-facility births ... Full text Open Access Cite

Accurate Dosing of Antiretrovirals at Home Using a Foilized, Polyethylene Pouch to Prevent the Transmission of HIV From Mother to Child.

Journal article Medicine · June 2015 Mother-to-child HIV transmission rates remain elevated in countries with high home birth rates. This risk can be dramatically reduced if infants receive antiretroviral (ARV) medication within 24 hours after birth. However, many barriers prevent access to t ... Full text Cite

Medical imaging in the global public health: Donation, procurement, installation, and maintenance

Journal article · October 1, 2014 Medical imaging equipment can have tremendous clinical value, and is in great need in the developing world. Like all equipment, the most basic X-ray imaging systems require complex considerations to maintain quality, most notably maintenance and repair. Th ... Full text Cite

Biomedical equipment technician capacity building using a unique evidence-based curriculum improves healthcare

Journal article Journal of Clinical Engineering · January 1, 2014 This article assesses the impact of a unique evidence-based biomedical equipment technician training program on the healthcare infrastructure and the productivity of technicians in Rwanda. Matched cohorts of hospitals included 9 technicians who received no ... Full text Cite

Capacity building for medical equipment technicians improves healthcare

Journal article Journal of Clinical Engineering · January 1, 2014 A midprogram assessment was conducted to determine if a continuing education program to instruct biomedical engineers in equipment repair and management is impacting healthcare in Honduras. A matched cohort study was conducted with 12 hospitals. Collected ... Full text Cite

Diffusion of novel healthcare technologies to resource poor settings.

Journal article Annals of biomedical engineering · September 2013 A new product has completed clinical trials in a distant, resource poor hospital using a few dozen prototypes. The data looks great. The novel medical device solves a widely felt problem. The next goal is to integrate the device into the country's healthca ... Full text Cite

Evaluation of the impact of a new biomedical equipment technician curriculum in Rwanda

Journal article Iet Conference Publications · December 1, 2012 The Developing World Healthcare Technology Laboratory (DHTLab) at Duke University recently developed the first evidence-based approach to training technicians to repair and maintain medical equipment in resource-poor settings, the BTA program. In this pape ... Full text Cite

Provision of biomedical equipment reference texts and manuals on e-readers in resource-poor settings

Journal article Iet Conference Publications · December 1, 2012 The Developing World Healthcare Technology Laboratory (DHTLab) at Duke University has developed a comprehensive, open-source biomedical equipment technician's (BMET) library. In this work we experimented with making the DHTLab BMET library and medical equi ... Full text Cite

Technologies for global health.

Journal article Lancet (London, England) · August 2012 Full text Cite

A Foilized Polyethylene Pouch for the Prevention of Transmission of HIV from Mother to Child.

Journal article The open biomedical engineering journal · January 2012 Many children become HIV+ due to mother-to-child transmission, a risk that can be largely eliminated if infants ingest antiretroviral (ARV) medications immediately after birth. As most mothers in Africa deliver at home, the ARV must be provided at their la ... Full text Open Access Cite

Simultaneous comparison of many triphasic defibrillation waveforms.

Journal article The open biomedical engineering journal · January 2012 Biphasic defibrillation waveforms are now accepted as being more effective at terminating ventricular fibrillation (VF) than monophasic waveforms. If two phases are better than one, this naturally leads to the hypothesis that additional phases improve effi ... Full text Cite

To the Editor:

Journal article Pacing and clinical electrophysiology : PACE · November 2011 Full text Cite

Use of simple hands-on design challenges for practicing engineering design principles

Journal article ASEE Annual Conference and Exposition, Conference Proceedings · August 25, 2011 The Biomedical Engineering program at Duke University offers five distinct capstone design experiences for our seniors. This approach provides flexibility to serve the needs of our diverse student population, however a one semester experience can be limiti ... Cite

Effectiveness of medical equipment donations to improve health systems: how much medical equipment is broken in the developing world?

Journal article Medical & biological engineering & computing · July 2011 It is often said that most of the medical equipment in the developing world is broken with estimates ranging up to 96% out of service. But there is little documented evidence to support these statements. We wanted to quantify the amount of medical equipmen ... Full text Cite

An affordable neonatal CPAP nasal interface for the developing world

Journal article 2011 IEEE 37th Annual Northeast Bioengineering Conference Nebec 2011 · June 16, 2011 The developing world has a number of challenges regarding healthcare, such as insufficient training and funding to properly care for patients. One problem involves neonates that are born with Respiratory Distress Syndrome (RDS), which is a lack of surfacta ... Full text Cite

Implantable intravascular defibrillator: evaluation of defibrillation waveforms with inferior vena cava electrode system.

Journal article Pacing and clinical electrophysiology : PACE · May 2011 BackgroundA percutaneously placed, totally intravascular defibrillator has been developed that shocks via a right ventricular (RV) single-coil and titanium electrodes in the superior vena cava (SVC) and the inferior vena cava (IVC). This study eva ... Full text Cite

Novel intravascular defibrillator: defibrillation thresholds of intravascular cardioverter-defibrillator compared to conventional implantable cardioverter-defibrillator in a canine model.

Journal article Heart rhythm · February 2011 BackgroundAn intravascular, percutaneously placed implantable defibrillator (InnerPulse percutaneous intravascular cardioverter-defibrillator [PICD]) with a right ventricular (RV) single-coil lead and titanium electrodes in the superior vena cava ... Full text Cite

Evidence-based approach to the maintenance of laboratory and medical equipment in resource-poor settings.

Journal article Medical & biological engineering & computing · July 2010 Much of the laboratory and medical equipment in resource-poor settings is out-of-service. The most commonly cited reasons are (1) a lack of spare parts and (2) a lack of highly trained technicians. However, there is little data to support these hypotheses, ... Full text Cite

A novel phototherapy device: the design community approach for the developing world.

Journal article IEEE engineering in medicine and biology magazine : the quarterly magazine of the Engineering in Medicine & Biology Society · March 2010 Phototherapy is the standard treatment for severe cases of hyperbilirubinemia in newborns. Phototherapy exposes the infants to light in the range of 400-500 nm to isomerize unconjugated bilirubin in the skin. Any light source that produces this wavelength ... Full text Cite

Duke University-Engineering World Health CUREs program: Developing: Developing new medical equipment

Journal article Iet Seminar Digest · December 1, 2008 The Duke University-Engineering World Health Competition for Underserved Resources and Economies (Duke-EWH CUREs) promotes the development of new healthcare technologies and non-profit businesses to help the world's least developed nations. This paper desc ... Full text Cite

Engineering world health: Lessons learned from six years of undergraduate service-learning in the developing world

Journal article ASEE Annual Conference and Exposition, Conference Proceedings · December 1, 2008 Engineering World Health is a fusion of engineers, scientists and physicians donating their time and talents to improve healthcare in disadvantaged areas around the world. The Duke University-Engineering World Health (Duke-EWH) Summer Institute is a unique ... Cite

Special session - Biomedical engineering ethics and standards in the developing world

Journal article Proceedings Frontiers in Education Conference Fie · December 1, 2007 Engineering educators and students are at the interface between biomedical engineering technology and the developing world. Through service learning efforts and organizations like Engineers Without Borders and Engineering World Health, engineers find thems ... Full text Cite

Barriers for medical devices for the developing world.

Journal article Expert review of medical devices · November 2007 Full text Cite

Effect of electrode surface area on thresholds for AC stimulation and ventricular fibrillation.

Journal article IEEE Trans Biomed Eng · October 2007 Unintended, weak AC stimulation (leakage currents) from medical devices can cause blood pressure collapse and ventricular fibrillation (VF), potentially even death. Yet, little is understood about AC cardiac stimulation. The objective of this paper is to e ... Full text Link to item Cite

Technologies for clinically relevant physiological measurements in developing countries.

Journal article Physiological measurement · August 2007 The 'Health for All by 2000' campaign included promotion of technologies that were known to be effective and inexpensive. The selected technologies were largely a failure. Among other problems, water pumps broke and could not be repaired in remote areas an ... Full text Cite

Design of health care technologies for the developing world.

Journal article Annual review of biomedical engineering · January 2007 Approximately 20 years ago, the international community embarked on a project to bring health care to everyone by the year 2000 featuring, among other things, technologies that were known to be effective and economical. It was largely a failure. In fact, h ... Full text Cite

The design of a low cost scintillating detector for a radiation meter

Journal article Proceedings of the IEEE Annual Northeast Bioengineering Conference Nebec · January 1, 2007 An x-ray detector will be designed for the Engineering World Health (EWH) organization to be incorporated into an ionizing radiation meter. This meter will be distributed to hospitals of the developing world to improve patient care. The meter will be able ... Full text Cite

Experimental evidence of improved transthoracic defibrillation with electroporation-enhancing pulses.

Journal article IEEE transactions on bio-medical engineering · October 2006 There is considerable work on defibrillation wave form optimization. This paper determines the impedance changes during defibrillation, then uses that information to derive the optimum defibrillation wave form.Methods part iTwelve guinea pigs and ... Full text Cite

Reply to "on the optimal defibrillation waveform - How to reconcile theory and experiment?"

Journal article IEEE Transactions on Biomedical Engineering · August 1, 2006 Full text Cite

Experimental verification of theoretical predictions concerning the optimum defibrillation waveform.

Journal article IEEE transactions on bio-medical engineering · August 2006 The efficacy of electrical therapy at terminating ventricular fibrillation is highly dependent on the waveform used. We present experimental results which test one theory for defibrillation waveform dependence. Forty-four defibrillation waveforms (22 monop ... Full text Cite

Effect of electrically insulating materials on magnetically induced electrical currents in a tissue-like medium

Journal article American Journal of Physics · April 1, 2006 Time varying magnetic fields can induce eddy currents in a conductor. Electrical currents also can be induced magnetically in the human body, and there has been considerable interest in the bioeffects of this phenomenon. We present an analytical model deri ... Full text Cite

The humanitarian efforts of biomedical engineers: An overview from the guest editor

Journal article IEEE Engineering in Medicine and Biology Magazine · January 1, 2006 Full text Cite

Design of a bilirubin light intensity tester for developing world hospitals

Journal article Proceedings of the IEEE Annual Northeast Bioengineering Conference Nebec · January 1, 2006 Phototherapy by bililights is the gold standard used to provide treatment for jaundiced neonates. Jaundice is the accumulation of bilirubin in the blood which, if not treated in neonates, can lead to severe retardation and physical abnormalities. Since bil ... Cite

Advances in electrical and mechanical cardiac mapping.

Journal article Physiological measurement · February 2005 Cardiac mapping--recording cardiac activity during electrophysiological testing--has evolved into an indispensable tool in studying the cardiac excitation process, analysing activation patterns, and identifying arrhythmogenic tissue. Cardiac mapping is a b ... Full text Cite

Analysis of the defibrillation efficacy for 5-ms waveforms.

Journal article Journal of cardiovascular electrophysiology · April 2004 IntroductionEmpirical studies have shown that biphasic defibrillation waveforms are more efficacious than monophasic waveforms. However, a more systematic approach to waveform development might be more productive. This study tested 147 multiphasic ... Full text Cite

Design of an integrated sensor for in vivo simultaneous electrocontractile cardiac mapping.

Journal article IEEE transactions on bio-medical engineering · February 2004 While there is extensive mapping of the spread of electrical activity in the heart, there have been no measurements of electrical and localized mechanical, or contractile, activity. Yet the development of effective treatments for diseases like chronic hear ... Full text Cite

Heart Rate Variability in Rats with Aldosterone-Induced Chronic Heart Failure

Journal article Annual International Conference of the IEEE Engineering in Medicine and Biology Proceedings · December 1, 2003 The renin-angiotensin-aldosterone system contributes to the pathophysiology of chronic heart failure. In this study, chronic heart failure is gradually induced in uninephrectomized rats (n = 4) by aldosterone infusion (0.75 μg/h) and high Na and low Mg die ... Cite

Engineering world health: A novel approach to teaching a global viewpoint

Journal article ASEE Annual Conference Proceedings · December 1, 2003 Engineering World Health has partnered with The University of Memphis to create The Engineering World Health Summer Institute. This unique study abroad program offers students an opportunity to receive hands-on technical skills in a foreign country while e ... Cite

Frequency dependence of the cardiac threshold to alternating current between 10 Hz and 160 Hz.

Journal article Medical & biological engineering & computing · November 2003 It is still unclear what fundamental criteria influence the ability of alternating current (AC) to induce ventricular fibrillation (VF) in vivo. As the VF threshold has a bowl-shaped relationship with frequency (showing a minimum threshold at some frequenc ... Full text Cite

Very-long-chain acyl-coenzyme a dehydrogenase deficiency in mice.

Journal article Circulation research · September 2003 Fatty acid oxidation (FAO) defects are inborn errors of metabolism clinically associated with cardiomyopathy and sudden infant death syndrome (SIDS). FAO disorders often present in infancy with myocardial dysfunction and arrhythmias after exposure to stres ... Full text Cite

Defibrillation causes immediate cardiac dilation in humans.

Journal article Journal of cardiovascular electrophysiology · August 2003 UnlabelledDefibrillation Causes Dilation.IntroductionPrior studies in isolated heart tissue have shown both excitation and deexcitation to be the primary mechanism of defibrillation. This article presents the first evidence in man of deex ... Full text Cite

Two-dimensional analysis of ventricular fibrillation in the guinea pig.

Journal article Journal of electrocardiology · April 2003 Cardiac arrhythmias are undesirable electrical activity in the heart. Ventricular fibrillation (VF) is a fatal cardiac arrhythmia and is characterized by the breakdown of organized electrical activity in the ventricular myocardium. However, little is known ... Full text Cite

Left ventricular geometry immediately following defibrillation: shock-induced relaxation.

Journal article American journal of physiology. Heart and circulatory physiology · March 2003 A previous two-dimensional (2D) ultrasound study suggested that there is relaxation of the myocardium after defibrillation. The 2D study could not measure activity occurring within the first 33 ms after the shock, a period that may be critical for discrimi ... Full text Cite

The defibrillation efficacy of high frequency alternating current sinusoidal waveforms in guinea pigs.

Journal article Pacing and clinical electrophysiology : PACE · February 2003 There have been few basic studies of alternating current (AC) defibrillation, despite growing interest in the ability of AC to terminate or alter ongoing fibrillation. Based on fibrillation threshold testing, it has been suggested that cardiac tissue is mo ... Full text Cite

T wave alternans: a marker of myocardial instability.

Journal article Progress in cardiovascular nursing · January 2003 T wave alternans is an electrocardiographic marker of myocardial electrical instability considered predictive for the development of lethal ventricular rhythms. Direct observation of this phenomenon on the electrocardiogram is rare. Subtle, nonvisible alte ... Full text Cite

Left ventricular volume changes after defibrillation

Journal article Annual International Conference of the IEEE Engineering in Medicine and Biology Proceedings · December 1, 2002 A previous study has shown that the cross-sectional area of the left ventricular cavity (LV) increases immediately after defibrillation, suggesting that the defibrillation shock may cause relaxation. Since a single area slice may not reflect the entire myo ... Cite

Ventricular wall thickness and volume during hemodynamic collapse produced by AC leakage current

Journal article Annual International Conference of the IEEE Engineering in Medicine and Biology Proceedings · December 1, 2002 Medical equipment can unintentionally allow the flow of power line current through the patient causing complete hemodynamic collapse without fibrillation. This study tests the hypothesis that static wall thickening accompanies AC induced collapse via an is ... Cite

Design of an integrated sensor for in-vivo simultaneous electrocontractile cardiac mapping

Journal article Annual International Conference of the IEEE Engineering in Medicine and Biology Proceedings · December 1, 2002 Cardiac mapping has evolved into an important tool in the study, diagnosis, and treatment of cardiac arrhythmias and other heart disorders in both research and clinical settings. Traditionally, cardiac mapping systems have been used to measure the electric ... Cite

A novel ultrasound technique to estimate right ventricular geometry during fibrillation.

Journal article Physiological measurement · May 2002 Finite element modelling of the heart for the purpose of studying the electric fields of defibrillation shocks requires knowledge of the geometry of the heart during fibrillation. However, the standard method of measuring this geometry, MRI. cannot be used ... Full text Cite

Large sample test of defibrillation waveform sensitivity.

Journal article Journal of cardiovascular electrophysiology · April 2002 IntroductionAn unknown mechanism causes defibrillation efficacy to be sensitive to the temporal pattern (waveform) of the delivered energy. Using a guinea pig model, we tested hypotheses in 140 defibrillation waveforms.Methods and results ... Full text Cite

Effect of 2,3 butanedione monoxime(BDM) on ventricular fibrillation

Journal article Computers in Cardiology · January 1, 2002 Optical mapping is commonly used to study ventricular fibrillation (VF). Electro-contractile uncouplers like 2,3 Butanedione Monoxime (BDM) are used in these studies to stop the mechanical activity, under the assumption that they do not have an effect on t ... Full text Cite

The response of intact guinea pigs to AC leakage currents

Journal article Computers in Cardiology · January 1, 2002 There was a difference in the standard for leakage current in the US and Europe. This difference existed largely because there was very little data on AC stimulation of the heart in situ. In this study, we examine AC stimulation of the in tact guinea pig. ... Cite

Mechanical response of the left ventricle during AC induced hemodynamic collapse

Journal article Computers in Cardiology · January 1, 2002 Medical equipment can unintentionally allow the flow of small amounts of AC current through the patient causing hemodynamic collapse without fibrillation. This study examines the mechanical response of the left ventricle during AC induced hemodynamic colla ... Cite

The engineering world health summer institute: A new educational opportunity

Journal article Annual International Conference of the IEEE Engineering in Medicine and Biology Proceedings · January 1, 2002 The Engineering World Health Summer Institute is a unique educational paradigm. EWH is a study abroad program which offers students an opportunity to receive hands-on technical training while volunteering in a developing country and earning college credit. ... Full text Cite

An unconditional exact test for small samples matched binary pairs

Journal article Journal of Modern Applied Statistical Methods · January 1, 2002 When investigators have N pairs of binary data, a common test for an increased rate of response is McNemar's test. However, McNemar's is an approximate, conditional test. An exact, unconditional test exists, but requires restrictive assumptions. Critical v ... Full text Cite

Mechanisms by which AC leakage currents cause complete hemodynamic collapse without inducing fibrillation.

Journal article Journal of cardiovascular electrophysiology · October 2001 IntroductionThe first study of weak alternating current (AC) stimulation in closed chest humans showed that complete hemodynamic collapse can occur below the threshold for inducing ventricular fibrillation (VF), a heretofore unknown danger to pati ... Full text Cite

Excitation of a cardiac muscle fiber by extracellularly applied sinusoidal current.

Journal article Journal of cardiovascular electrophysiology · October 2001 IntroductionThe goal of this study was to examine the effect of AC currents on a cardiac fiber. The study is the second in a series of two articles devoted to the subject. The initial study demonstrated that low-strength sinusoidal currents can ca ... Full text Cite

Defibrillation and the geometry of the heart: a novel measurement with implications for defibrillation mechanisms.

Journal article Physiological measurement · May 2001 We present a novel measurement for studying defibrillation mechanisms: the time course of changes in the size of the left ventricular (LV) cavity within 500 ms following defibrillation. Mechanical changes can be linked to electrical mechanisms via an under ... Full text Cite

Analysis of mice heart rate variability obtained through plethysmograph power spectrum

Journal article Computers in Cardiology · January 1, 2001 In this work we focus on the measurement of heart rate variability (HRV) from the murine plethysmograph. We check whether the recently proposed heart instantaneous frequency (HIF) idea is a viable tool to assess HRV under normal and the adverse conditions ... Full text Cite

Can an RC membrane model predict the efficacy of a defibrillation waveform: An analysis of defibrillation mechanisms in 140 defibrillation waveforms

Journal article Computers in Cardiology · January 1, 2001 Different defibrillation waveforms exhibit different efficacies. It has been proposed that a resistor-capacitor (RC) model of the myocardial membrane can explain these differences. Both the maximum capacitor voltage (charge banking) and the remaining volta ... Cite

Defibrillation impedance: including an inductive element

Journal article Computers in Cardiology · December 1, 2000 A new equivalent circuit model is proposed to quantify the defibrillation impedance for short pulses. Six male guinea pigs (850-1050g) were used. A defibrillator delivered square voltage pulses (200V). Three electrode placements were tested randomly: Norma ... Cite

60 Hz leakage currents cause complete hemodynamic collapse below VF threshold

Journal article Annual International Conference of the IEEE Engineering in Medicine and Biology Proceedings · December 1, 2000 This figure summarizes the data showing the threshold for simulation (bold line), the minimum for VF (dotted line) and the average value for collapse. With the exception of one point (80Hz), there is always a point below the strength causing VF where AC st ... Cite

Water soluble propofol anesthesia: an effective and inexpensive alternative.

Journal article Lab animal · October 2000 The authors discuss solubilized propofol, and demonstrate its acute use in guinea pigs as an effective, less expensive, easy-to-use alternative for laboratory animal anesthesia. ... Full text Cite

A simulation study evaluating the performance of high-density electrode arrays on myocardial tissue.

Journal article IEEE transactions on bio-medical engineering · July 2000 Multielectrode arrays used to detect cellular activation have become so dense (electrodes per square millimeter) as to jeopardize the basic assumptions of activation mapping; namely, that electrodes are points adequately separated as to not interfere with ... Full text Cite

Construction of a very high-density extracellular electrode array.

Journal article Am J Physiol Heart Circ Physiol · July 2000 Cellular activation mapping (specifying in time and space the electrical activation sequence of cells) is a well-established basic research tool in cardiac, neural, and gastric physiology. Much recent research in cardiac mapping has focused on large arrays ... Link to item Cite

Hemodynamic collapse, geometry, and the rapidly paced upper limit of ventricular vulnerability to fibrillation by T-wave stimulation.

Journal article Journal of electrocardiology · July 2000 There is an upper limit to the vulnerability (ULV) of the ventricles to fibrillation (VF) induced by T-wave stimuli. Across species, disease states, and pharmacological treatments, the ULV is correlated to the defibrillation threshold (DF50). However, one ... Full text Cite

Construction of a very high-density extracellular electrode array.

Journal article American journal of physiology. Heart and circulatory physiology · July 2000 Cellular activation mapping (specifying in time and space the electrical activation sequence of cells) is a well-established basic research tool in cardiac, neural, and gastric physiology. Much recent research in cardiac mapping has focused on large arrays ... Full text Cite

Open-thorax guinea pig model for defibrillation.

Journal article Laboratory animal science · December 1999 Background and purposeGuinea pigs are used as models for study of ventricular tachyarrhythmias (VT); however, the tachyarrhythmia often is transient and does not persist. We developed an open-thorax guinea pig model of sustained ventricular fibril ... Cite

Mechanism by which pacing rate affects the upper limit of ventricular vulnerability to fibrillation by T-wave stimulation

Journal article Annual International Conference of the IEEE Engineering in Medicine and Biology Proceedings · December 1, 1999 A stimulus in the T-wave of the heart's normal cycle can alter the heart's activity. However, there is an upper limit (ULV) to stimulus strength that can cause conversion to ventricular fibrillation (VF). Since the ULV is correlated with the defibrillation ... Cite

AC leakage currents cause complete hemodynamic collapse below the ventricular fibrillation threshold

Journal article Computers in Cardiology · December 1, 1999 In 1993, the American standard for leakage current through the heart under a single-fault condition was increased from 10 μA to 50 μA rms. Both the original 10 μA standard and the new 50 μA standard were based on estimates of the ability of 60 Hz AC curren ... Cite

A four-shock Bayesian up-down estimator of the 80% effective defibrillation dose.

Journal article Journal of cardiovascular electrophysiology · July 1999 IntroductionNew defibrillation techniques are often compared to standard approaches using the defibrillation threshold. However, inference from thresholding data necessitates extrapolation from reactions to relatively ineffective shocks, an error ... Full text Cite

Cardiovascular collapse caused by electrocardiographically silent 60-Hz intracardiac leakage current. Implications for electrical safety.

Journal article Circulation · May 1999 BackgroundThe national standard for safe 60-Hz intracardiac leakage current under a single-fault condition is 50 microA. This standard is intended to protect patients from alternating current (AC) at levels below the threshold for sensation, but t ... Full text Cite

Defibrillation and the upper limit of vulnerability to fibrillation in a transthoracic guinea pig model.

Journal article Journal of electrocardiology · April 1999 Recent studies have shown sustained tachyarrhythmias in guinea pigs. We hypothesized that guinea pigs could be used as a model of ventricular fibrillation, focusing on defibrillation waveform efficacy and the upper limit of vulnerability to fibrillation. I ... Full text Cite

Exposures to lead-based paint dust in an inner-city high school

Journal article American Industrial Hygiene Association Journal · March 1, 1999 In response to concerns about lead-based paint (LBP) in an 85-year old high school, an evaluation was conducted to determine whether a lead exposure hazard existed for adult school staff. Deteriorating LBP was present on walls and ceilings throughout the s ... Cite

Experimental cardiac tachyarrhythmias in guinea pigs.

Journal article Journal of electrocardiology · January 1999 Despite years of intense research into the mechanisms of defibrillation, there remain many unanswered questions. In many fields, hypotheses are first tested in rodent models before confirming the results in larger animals. This work suggests the guinea pig ... Full text Cite

The effect of critical point location and membrane kinetics on VF induction by T-wave stimulation

Journal article Computers in Cardiology · December 1, 1998 A strong stimulus delivered in the T-wave of a normal cardiac cycle can induce ventricular fibrillation. The critical point mechanism is thought to be responsible for this phenomenon. However, rapid pacing can cause an otherwise benign strong T-wave stimul ... Cite

Optical measurement of transmembrane potential in intact cardiac tissues using fluorescent resonance energy transfer

Journal article Computers in Cardiology · December 1, 1998 Fluorescent Resonance Energy Transfer [FRET] is the transfer of excitation energy from a donor fluorescent molecule to an acceptor fluorescent molecule. FRET has been developed to achieve fast, ratiometric, transmembrane potential sensitive fluorescence ch ... Cite

Virtual electrode effects in transvenous defibrillation-modulation by structure and interface: evidence from bidomain simulations and optical mapping.

Journal article Journal of cardiovascular electrophysiology · September 1998 IntroductionOur goal in this combined modeling and experimental study was to gain insight into the transmembrane potential changes in defibrillation conditions, namely, when shocks are delivered by an implantable cardioverter defibrillator (ICD). ... Full text Cite

The effect of inducing ventricular fibrillation with 50-Hz pacing versus T wave stimulation on the ability to defibrillate.

Journal article Pacing and clinical electrophysiology : PACE · May 1998 When testing an ICD, there are at least two techniques for inducing ventricular fibrillation: (1) high frequency (approximately equal to 50 Hz) pacing; and (2) a single T wave stimulus. It is generally assumed that these two methods yield similar results. ... Full text Cite

Improved guinea pig model of cardiac tachyarrhythmias.

Journal article Laboratory animal science · February 1998 Guinea pigs are frequently used as models for ventricular tachyarrhythmias, including polymorphic ventricular tachycardia (VT) and ventricular fibrillation. However, applications of the model for short-term therapies are limited because the arrhythmias are ... Cite

Constructing a multichannel electrocardiography system from a few standardized, high-level components.

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

Impact of endocardial lead position on transvenous defibrillation efficacy: A simulation study

Journal article Computers in Cardiology · December 1, 1997 This computational study examines the dependence of defibrillation threshold on the transvenous lead location in active-can transvenous lead defibrillation systems. Finite element models of the human thorax that incorporate (i) isotropic, (ii) realistic fi ... Cite

Bayesian estimator of the minimum stimulus strength to induce ventricular fibrillation

Journal article Computers in Cardiology · December 1, 1997 The American standard for AC current leakage in the myocardium was recently raised from 10 microamps to 50 microamps to match European standards. A lack of fibrillation (VF) induction data from humans has made it difficult to support or reject the increase ... Cite

Spatial effects from bipolar current injection in 3D myocardium: Implications for conductivity measurements

Journal article Computers in Cardiology · December 1, 1997 This study aims at predicting the spatial extent of the polarization in myocardium (surface and in-depth patterns) resulting from bipolar current injection. The three-dimensional effects resulting from transmural fiber rotation and unequal anisotropy ratio ... Cite

Extended cardiac tachyarrhythmias in guinea pigs

Journal article Annual International Conference of the IEEE Engineering in Medicine and Biology Proceedings · December 1, 1997 Guinea pigs are frequently used as models for ventricular tachyarrhythmias, including polymorphic ventricular tachycardia and ventricular fibrillation. However, applications of the model for the development of new cardioversion and defibrillation technolog ... Cite

Scalable and shiftable Bayesian defibrillation efficacy estimator

Journal article Annual International Conference of the IEEE Engineering in Medicine and Biology Proceedings · December 1, 1997 When an automatic defibrillator is implanted, it is essential to accurately estimate a highly effective defibrillation dose from a minimum number of fibrillation episodes. An optimum, fixed step-size, up-down Bayesian protocol has been previously proposed ... Cite

In vivo measurement of ventricular geometry during fibrillation

Journal article Annual International Conference of the IEEE Engineering in Medicine and Biology Proceedings · December 1, 1997 Both experimental and modeling studies have shown that ventricular geometry plays a role in the efficacy of defibrillation shocks. This study uses transthoracic echocardiography to measure the temporal changes in the geometry of the right ventricle (RV) du ... Cite

Statistical analysis of signals from an intracavitary probe in a diseased heart.

Journal article Medical & biological engineering & computing · September 1997 A model study introduces the use of statistical signal processing to analyse the signals from an intracavitary probe. A complete derivation is given for the detection of one type of arrhythmogenic substrate, myocardial infarctions (MIs). Both the use of st ... Full text Cite

The ventricular defibrillation and upper limit of vulnerability dose-response curves.

Journal article Journal of cardiovascular electrophysiology · August 1997 IntroductionA stimulus delivered in the T wave of a paced cardiac cycle can induce ventricular fibrillation (VF). If the stimulus strength is increased, the probability of inducing VF decreases. This study determines an ideal mathematical model (a ... Full text Cite

An up-down Bayesian, defibrillation efficacy estimator.

Journal article Pacing and clinical electrophysiology : PACE · May 1997 In both the clinic and the laboratory, efficacy estimators are used to estimate the shock strength required to achieve a given defibrillation success rate. In the clinic, efficacy estimators are used to estimate highly effective doses (i.e., the shock stre ... Full text Cite

The mechanism of the ULV dose-response curve: A model study

Journal article Computers in Cardiology · December 1, 1996 A stimulus given in the T-wave (a ULV stimulus) of a paced cardiac cycle can induce ventricular fibrillation (VF). However, if the ULV stimulus strength is increased, the probability of inducing VF drops in a dose-response fashion. This paper presents a hy ... Cite

Estimating myocardial activation times by maximum likelihood estimation

Journal article Computers in Cardiology · December 1, 1996 In a cardiac isochronal map, myocardial dynamics are represented by activation times. Traditionally, adhoc methods (typically using the local minimum derivative of à unipolar electrogram, i.e., minimum first derivative algorithm) are used to detect myocard ... Cite

Estimating defibrillation efficacy using combined upper limit of vulnerability and defibrillation testing.

Journal article IEEE transactions on bio-medical engineering · January 1996 It is frequently necessary, both clinically and in the laboratory, to estimate how strong a stimulus is required to defibrillate. Current techniques for forming such estimates require the repeated induction of ventricular fibrillation (VF) and subsequent a ... Full text Cite

Integration of student presentations into advanced classes

Journal article Proceedings Frontiers in Education Conference · December 1, 1995 At the City College of New York, a project has been started to integrate student presentations into a sequence of three advanced undergraduate classes in engineering. Every undergraduate biomedical engineering student must take two of these three classes. ... Cite

Matched-pairs defibrillation efficacy hypothesis test

Journal article Annual International Conference of the IEEE Engineering in Medicine and Biology Proceedings · December 1, 1995 It is common to statistically test the hypothesis that one defibrillation technique is better than another. A standard approach is to estimate the DF50 (the shock strength which defibrillates 50% of the time) on a set of subjects under test and ... Cite

Effect of rapid pacing and T-wave scanning on the relation between the defibrillation and upper-limit-of-vulnerability dose-response curves.

Journal article Circulation · September 1, 1995 BACKGROUND: The critical-point and upper-limit-of-vulnerability (ULV) hypotheses predict that the ULV dose-response curve should be steeper and to the right of the defibrillation (DF) curve. Yet, some recent experimental data contradict this prediction. Tw ... Full text Link to item Cite

Comparison of upper limit of vulnerability and defibrillation probability of success curves using a nonthoracotomy lead system.

Journal article Circulation · February 1995 BackgroundAn upper limit to the strength of shocks that induce fibrillation during the vulnerable period, the upper limit of vulnerability (ULV), has been shown to exist in both humans and animals. The purpose of this study was to compare ULV and ... Full text Cite

Bayesian up-down estimator of the 80% effective defibrillation dose

Journal article Annual International Conference of the IEEE Engineering in Medicine and Biology Proceedings · December 1, 1994 An implantable cardioverter-defibrillator (ICD) can prevent sudden cardiac death. However, the ICD stimulus strength must be set appropriately for each patient. Current protocols for estimating the appropriate stimulus strength require many attempts at def ... Cite

RAPID PACING MOVES THE UPPER LIMIT OF VULNERABILITY HIGHER ON THE DEFIBRILLATION PROBABILITY OF SUCCESS CURVE

Journal article JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY · February 1, 1994 Link to item Cite

Optimum detection of myocardial infarctions with an intracavitary probe

Journal article Computers in Cardiology · December 1, 1993 Small myocardial infarctions (MI) may be life threatening, but cannot be easily detected using standard, body surface electrocardiography. This model study explores the use of an intracavitary probe to detect small MI's. The likelihood ratio is used for de ... Cite

Generalized electrocardiographic spherical shells model with emphasis on the paced infarcted heart

Journal article Computers in Cardiology · December 1, 1993 The spherical shells model (SSM) is a useful tool for qualitative investigations of the electrical events in the thorax during a heart beat. This paper presents a scheme to extend the SSM to allow for general dipolar source configurations. A model is sugge ... Cite

Acoustic Classification of Abyssopelagic Animals

Journal article IEEE Journal of Oceanic Engineering · January 1, 1993 The unique environment of the abyssal plains allows many simplifying assumptions, facilitating the acoustic classification of an animal into one of two groups. The most important assumptions are based on low population densities and available target streng ... Full text Cite

Estimating the 95% effective defibrillation dose

Journal article IEEE Trans. Biomed. Eng. (USA) · 1993 Minimum-squared-error (MinSE) testing protocols and a MinSE estimator that accurately estimate the voltage that defibrillates 95% of the time (the ED95) are presented. The MinSE experimental procedures, presented in the form of lookup tables, detail the re ... Full text Link to item Cite

Defibrillation efficacy estimation using Bayesian estimation theory

Journal article Proceedings ICASSP IEEE International Conference on Acoustics Speech and Signal Processing · January 1, 1993 An implanted cardioverter/defibrillator (ICD) detects ventricular fibrillation (VF), a potentially fatal lack of electrical coordination in the heart, and then discharges a capacitor through the heart, hopefully restoring normal rhythm. One of the clinical ... Cite

Blood lead levels in incinerator workers.

Journal article Environmental research · October 1992 Questions have been raised concerning the safety of mass burn incineration and its role in solid waste management. In 1989, the New York City Office of Occupational Safety and Health examined air levels of metals in New York City incinerators and found tha ... Full text Cite

Optimum estimation of the 95 percent effective defibrillation dose

Journal article Proceedings of the Annual Conference on Engineering in Medicine and Biology · December 1, 1991 Optimum Bayesian algorithms were compared with three currently used approaches to estimating the leading edge voltage which successfully defibrillates 95% of the time (ED95). Two different design methods were used for the Bayesian techniques. Five dogs wer ... Cite

Dioxin levels in blood of municipal incinerator workers

Journal article Medical Science Research · June 24, 1991 Cite

Optimizing existing defibrillation thresholding techniques

Journal article Proceedings of the Annual Conference on Engineering in Medicine and Biology · December 1, 1990 A signal-estimation theory approach to the problem of optimizing defibrillation thresholding techniques leading to an optimum stepping algorithm is presented. The results guarantee maximum average performance by achieving the minimum average cost. It is sh ... Cite