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Engineering in Medicine and Biology Magazine, IEEE

Issue 6 • Date November-December 2009

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Displaying Results 1 - 25 of 41
  • IEEE Engineering in Medicine and Biology Magazine - Front cover

    Page(s): c1
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  • Table of contents

    Page(s): 1 - 2
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  • A brief discussion of abbreviations [From the Editor]

    Page(s): 3 - 3, 8
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  • Highlights [President's Message]

    Page(s): 4 - 4, 8
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  • Online visibility: EMBS gets e-savvy [Student Activities]

    Page(s): 5 - 6, 8
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  • IEEE EMBC'10

    Page(s): 9
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  • Student activities around the world: IEEE EMBS UKRI student club features PGBIOMED 2009

    Page(s): 10 - 10, 12, 14
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  • ISBI 2010 - Call for papers

    Page(s): 11
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  • AMA Conference

    Page(s): 13
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  • Coulter Translational Research Awards

    Page(s): 14
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  • Call for Nominations 2010 IEEE EMBS Awards

    Page(s): 15
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  • Cardiovascular variability [Introduction to the special issue]

    Page(s): 16 - 17
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  • WHO call for innovative technologies

    Page(s): 17
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  • Approximate entropy for all signals

    Page(s): 18 - 23
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1569 KB) |  | HTML iconHTML  

    In this study, computer simulation examples consisting of various signals with different complexity were compared. It was found that neither approximate entropy (ApEn) nor sample entropy (SampEn) methods was accurate in measuring signals' complexity when the recommended values (e.g., m = 2 and r = 0.1-0.2 times the standard deviation of the signal) were strictly adhered to. However, when we selected the maximum ApEn value as determined by considering many different r values, we were able to correctly discern a signal's complexity for both synthetic and experimental data. However, this requires that many different choices of r values need to be considered. This is a very cumbersome and time-consuming process. Thus, the primary goal of the present work is to illustrate our recently developed method that can automatically select the appropriate tolerance threshold value r, which corresponds to the maximum ApEn value, without resorting to the calculation of ApEn for each of the threshold values selected in the range of zero and one times the standard deviation. View full abstract»

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  • Concealed conduction effects in the atrium

    Page(s): 24 - 29
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1026 KB) |  | HTML iconHTML  

    Here, we present new results obtained from a 1-D model of the atrium, with both the sinoatrial (SA) and atrioventricular (AV) nodes included. This model is able to reproduce forward and backward propagation between the SA and AV node. These nodes were approximated by a 1-D chain of diffusively coupled, modified relaxation oscillators. The atrial muscle was modeled using a chain of modified FitzHugh-Nagumo (FHN) equations. The FHN model captures the key features of excitable media and is widely used as a simple model of cardiac muscle electrical activity. The complete model consists of three segments: the SA node (15 elements), the atrial muscle (90 elements), and the AV node (15 elements) coupled diffusively at the interfaces and was solved numerically using the Euler method. The model is dimensionless, but the parameters were set in such a way that the period of the oscillations was numerically of the order of the length of RR intervals in human heart rate variability recordings. The model is able to reproduce the low-pass filtering properties of the SA node. The interspike intervals (ISIs) of the calculated action potentials of the AV node of our model were compared, with RR intervals obtained from two selected 24-h Holter recordings of patients of the Institute of Cardiology at Warszawa: one recorded in a 11-year-old girl with hypertrophic cardiomyopathy and a second one recorded in a patient with a possible SA block and no ventricular arrhythmia. View full abstract»

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  • Tuning of the sequence technique

    Page(s): 30 - 34
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (574 KB) |  | HTML iconHTML  

    The sequence method was first described by Di Rienzo in cats and applied in different species including humans. Until now, no systematic study of spontaneous baroreflex sensitivity (BRS) has been performed by the sequence method in mice. This study aimed to characterize the best estimates of BRS using the sequence method by tuning all the possible parameters, specifically, the number of beats involved in a sequence, the minimal changes in blood-pressure (BP) ramps, and the minimal changes in pulse-interval (PI) ramps. Also, the relevance to set a minimal correlation coefficient in the regression line between BP and PI was tested. An important point was the delay to be applied between BP and PI. This delay represents the physiological time for the baroreflex loop to efficiently correct the BP variations. View full abstract»

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  • MagIC system

    Page(s): 35 - 40
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1522 KB) |  | HTML iconHTML  

    In the health-care area, there is a growing demand for devices capable of monitoring cardiorespiratory function in a simple and comfortable way without interfering with the patient's behavior. Smart monitoring systems are also requested for the recording of vital signs in healthy subjects for research, assessment of performances, safety, and injury prevention purposes. Typical nonclinical areas of application include ergonomics, occupational medicine, wellness, and sport. This article describes the issues of the garment design and real-time signal processing during the tuning of MagIC for a nonclinical use. The new methodology for the optimization of the garment structure is reported and the solution adopted for estimating multifactorial parameters from the stream of data flowing from the vest is discussed. Additionally, results obtained during parachutists' jumps are also illustrated as a practical example of applicability of MagIC in nonclinical environments. View full abstract»

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  • ECG fingerprints of obstructed breathing in sleep apnea patients

    Page(s): 41 - 48
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3166 KB) |  | HTML iconHTML  

    This article aims to identify the potential indicators of obstructive apnea (OA) in the ECG, based on the traces of QRS area from multiple ECG leads. We compare the difference in these traces' phase relation found during and after each OA episode to the difference between the first and second half of the OA and between split halves of epochs of normal respiration (NR). View full abstract»

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  • Modeling fetal--maternal heart-rate interaction

    Page(s): 49 - 53
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (481 KB) |  | HTML iconHTML  

    The aim of this work was to examine the factors that might be involved in producing the epochs of coordination between fetal and maternal heart rate by comparing the occurrence of such coordination under conditions of spontaneous and controlled maternal breathing with the occurrence of coordinated epochs produced by a simple model of the experimental conditions. View full abstract»

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  • Autonomic neural control of cerebral hemodynamics

    Page(s): 54 - 62
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1026 KB) |  | HTML iconHTML  

    The present article examines the role of autonomic neural control on both dynamic pressure autoregulation and CO2 reactivity in the frequency range between 0.005 and 0.40 Hz by analyzing experimental data from healthy humans and using a nonlinear multivariate modeling approach. The data were obtained during control conditions and autonomic ganglionic blockade, induced by intravenous infusion of trimethaphan. This approach has been successfully used previously to describe cerebral hemodynamics during resting conditions and orthostatic stress. View full abstract»

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  • Effect of cushing response on systemic arterial pressure

    Page(s): 63 - 71
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1650 KB) |  | HTML iconHTML  

    This work investigates the complex relationships between cerebrovascular dynamics, intracranial pressure (ICP), Cushing response, and short-term systemic regulation via an original mathematical model. The model has been used to analyze the effects of Cushing response on cardiovascular and cerebrovascular quantities during constant ICP elevation and during the occurrence of ICP plateau waves and to investigate the conditions leading to system instability with the formation of slow (0.05-0.1 Hz) arterial pressure waves. The model may be of value to assist clinicians in finding the balance between clinical benefits of Cushing response and its shortcomings. View full abstract»

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  • Complexity of the short-term heart-rate variability

    Page(s): 72 - 78
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1360 KB) |  | HTML iconHTML  

    This work has proposed a methodology based on the concept of entropy rates to study the complexity of the short-term heart-rate variability (HRV) for improving risk stratification to predict sudden cardiac death (SCD) of patients with established ischemic-dilated cardiomyopathy (IDC). The short-term HRV was analyzed during daytime and nighttime by means of RR series. An entropy rate was calculated on the RR series, previously transformed to symbol sequences by means of an alphabet. A statistical analysis permitted to stratify high- and low-risk patients of suffering SCD, with a specificity (SP) of 95% and sensitivity (SE) of 83.3%. To get a better characterization of short-term HRV, the study has also considered the adjustment of the parameters involved in the proposed methodology. Finally, a statistical analysis was applied to recognize valid prognostic markers. View full abstract»

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  • Autonomic cardiovascular modulation

    Page(s): 79 - 85
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1166 KB) |  | HTML iconHTML  

    The aim of the study was twofold: first, to validate symbolic analysis as a tool capable of assessing autonomic cardiovascular regulation in rats and, second, to investigate neural cardiovascular regulation during the progression of ischemic induced chronic heart failure (CHF) in two groups of rats, a control group and a group treated with chronic administration of the mineralocorticoid receptor antagonist SP, a drug playing a protective role over cardiovascular regulation. View full abstract»

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  • Respiratory sinus arrhythmia on the ESA-short-arm human centrifuge

    Page(s): 86 - 91
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (701 KB) |  | HTML iconHTML  

    In this article, we investigated the hypothesis that the effects of hypergravity on respiratory sinus arrhythmia (RSA) can mimic the effects observed after spaceflight cardiovascular deconditioning. Artificial gravity along the head-to-feet axis on a short-arm centrifuge induces gravity gradients. This physiological condition of significantly higher g at the feet than at the heart level is specific and likely induces blood sequestration in the lower limbs. After spaceflight, astronauts are in a condition of cardiovascular deconditioning, where blood pooling in the lower part of the body and autonomic adaptation are factors contributing to orthostatic intolerance and changes in heart-rate variability (HRV). ECG and respiration were recorded during imposed and controlled breathing (ICB) protocols, which were repeated at different levels of artificial gravity as well as during supine and standing control conditions, and the changes were analyzed. View full abstract»

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  • Hippocampal gamma oscillations in rats

    Page(s): 92 - 95
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (346 KB) |  | HTML iconHTML  

    In this article, we investigate the influence of acute exposure to 2-aminoethoxy-diphenylborate (2-APB), a membrane-permeable inositol 1,4,5-trisphosphate (IP3) receptor, and store-operated Ca2+ channel (SOC) blocker on the complexity of hippocampal gamma oscillations. Our central hypothesis is that acute exposure to 2-APB significantly reduces the hippocampal gamma oscillations. To test this hypothesis, we use brain-slice recordings and the advanced nonlinear dynamical analysis method based on the Lempel-Ziv (LZ) estimator. Our nonlinear dynamical analysis results estimated from brain-slice recordings suggested that 2-APB exposure significantly reduces the hippocampal gamma oscillations. View full abstract»

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Aims & Scope

IEEE Engineering in Medicine and Biology Magazine contains articles on current technologies and methods used in biomedical and clinical engineering.

 

This Magazine ceased publication in 2010. The current retitled publication is IEEE Pulse.

Full Aims & Scope