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Engineering in Medicine and Biology Magazine, IEEE

Issue 1 • Date Jan.-Feb. 1998

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Displaying Results 1 - 15 of 15
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  • Characteristics of multichannel ECG recordings during human ventricular tachyarrhythmias

    Page(s): 39 - 44
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    Ventricular tachyarrhythmias are a leading cause of mortality. Although ventricular tachycardia (VT) is well understood, ventricular fibrillation (VF) remains an important clinical problem because fundamental information about the mechanisms of this arrhythmia in human hearts is still in short supply. While a number of therapeutic options are available for terminating or treating VT, the best hope for a patient experiencing VF is prompt defibrillation. This article examines approaches to analyzing multichannel data recorded during routine electrophysiology studies for the purpose of obtaining quantitative information about human tachyarrhythmias. View full abstract»

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  • Compression of multichannel ECG through multichannel long-term prediction

    Page(s): 109 - 115
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    The need for efficient coding of ECG signals is continually increasing with modern use of long-term monitoring and telemedicine. Here, the authors present an algorithm based on long-term prediction (LTP) compression. The single-channel LTP algorithm has been generalized to the multichannel case and is called the MC-LTP algorithm. This algorithm compresses PQRST beats using a pattern codebook with "typical" beats. View full abstract»

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  • Modeling spontaneous minute volume in coronary artery bypass graft patients

    Page(s): 122 - 127
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (703 KB)  

    This article presents a mathematical method by which the future trajectory of patient spontaneous minute volume (SMV) may be predicted in the postoperative weaning period. The method outlined enables critical-care staff to predict the SMV trajectory up to 30 minutes into the future. Having this capability enables physicians, respiratory therapists, and nurses to more efficiently guide patient treatment and schedule rounds within the ICU. View full abstract»

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  • The zero of potential

    Page(s): 128 - 136
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    The zero of potential has been the subject of controversy in both electrocardiographic and electroencephalographic literature. In this article zero of potential is discussed in a historical context. It is noted that there is no meaningful zero of potential on a bounded, insulated volume conductor such as the body, and the effect of the reference for recording potentials on surface potential maps is discussed. View full abstract»

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  • Bioelectrical Impedance Techniques In Medicine [Book Reviews]

    Page(s): 141
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    Freely Available from IEEE
  • Systems for measuring and tracking electrophysiologic distributions

    Page(s): 56 - 61
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1384 KB)  

    Electrocardiographic mapping has played an important role in the study and analysis of cardiac electrophysiologic phenomena. The first systems used for experimental or clinical studies were expensive, cumbersome, and limited in their ability to sample the complex electrophysiologic events associated with cardiac function and disease. New insights into the mechanisms of arrhythmias and the need for timely detection and characterization of changing cardiac states have made it essential that new tools be available to measure the spatial characteristics and dynamics of electrophysiologic events. For example, observation of the distribution and dynamics of ventricular repolarization is critical to predicting arrhythmia prone states, detecting reperfusion or reocclusion in patients undergoing post myocardial infarction therapy or angioplasty, or to accurately detect acute infarction in patients presenting with chest pain. Technology now permits affordable, flexible systems for making the critical observations. The authors present an example of such a system and its applications in this article View full abstract»

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  • Extracting endocardial borders from sequential echocardiographic images

    Page(s): 116 - 121
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    The authors discuss using mathematical morphology and temporal information (TI) to improve contour accuracy in the segmentation of 2D echo images. When the input consists of a sequence of images with poor quality, TI is used to assist the contour-extraction process. Spatial information of the contour in Frame i-1 is combined with the initial contour in Frame i to give a better estimation of the initial contour in Frame i. The results indicate that adding TI improves the accuracy of the generated contour, especially when the image quality is poor. The additional process does not affect the efficiency of the algorithm View full abstract»

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

    Page(s): 34 - 38
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    Multichannel systems for electrocardiography must be able to reliably measure and store large numbers of simultaneous low-frequency analog signals, while providing high gain, protection against defibrillation, and adequate electrical isolation. In the past, these specifications have been unique enough to force investigators to build up their systems from thousands of basic electronic components, like commercial integrated circuit amplifiers, power supplies, and analog-to-digital converters. It can take years to design, build, and debug a cardiac mapping system from basic components. The long development time and the need for specialized training to design from basic components forced some investigators to buy complete mapping systems or simply to avoid multichannel mapping. However, there is now another approach for these investigators. Recent advances in electronics, most notably the advent of high-speed open-industry bus standards, have made it possible to construct multichannel systems from just a few high-level off-the-shelf (standardized) components. The off-the-shelf approach can be used by most investigators without specialized training. This article describes the high level components of an off-the-shelf mapping system and the selection of those components for a particular application View full abstract»

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  • Where did the U.S. patent laws come from?

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    Where did the U.S. patent laws come from? One answer is from from the greed of English kings and queens. To raise money for themselves and their friends, the kings and queens of England adopted a policy of granting monopolies called “letters patents” for everyday goods such as vinegar, wine, salt, paper, oil, bottles, you name it. The crown sold these letters patents to brokers (or gave them to friends and supporters), who in turn sold them to particular companies interested in trading in the various goods. Over the years the U.S. Congress has enacted a series of comprehensive Patent Statutes, the first of which went into effect in 1790 and the most recent of which was enacted in 1952. Congress has also regularly fine-tuned the Patent Statutes in major and minor ways to respond to perceived needs in the country's continuing efforts to encourage innovation and thus grow the economy. Various stages of U.S. patent law can be identified in this process of legislating rewards for innovation. Initially, before 1836, U.S. patents were granted without examination, as is still done in some parts of the world. This left the issue of patent validity solely to the courts, which was unsatisfactory for a growing economy. In response, Congress created the Patent Office in 1836 and directed that Office to conduct a thorough examination of the prior art before a patent was issued. The Patent Office also was charged with resolving disputes between rival inventors and disseminating the technical information contained in patents to the public View full abstract»

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  • A system for in-vivo cardiac optical mapping

    Page(s): 95 - 108
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    Optical mapping of cardiac electrical activity is a valuable technique for studying arrhythmias, particularly the effects of defibrillation shocks. This technique has been exclusively applied to in-vitro preparations of hearts or tissues removed from an animal. But verification of experimental results and hypotheses is ideally performed in vivo on the heart as it remains in place in the animal. However, in-vitro optical mapping instrumentation and techniques cannot be easily applied in vivo. This article describes a system the authors developed to address this problem View full abstract»

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  • Classifying multichannel ECG patterns with an adaptive neural network

    Page(s): 45 - 55
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    In this article the authors describe the application of a new artificial neural network model aimed at the morphological classification of heartbeats detected on a multichannel ECG signal. They emphasize the special characteristics of the algorithm as an adaptive classifier with the capacity to dynamically self-organize its response to the characteristics of the ECG input signal. They also present evaluation results based on traces from the MIT-BIH arrhythmia database View full abstract»

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  • Recent progress in inverse problems in electrocardiology

    Page(s): 73 - 83
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    The considerable progress achieved in the inverse problem of electrocardiography over the last decade has provided grounds for optimism about the possibility of approaching significant clinically relevant applications in the next decade. However, there are a number of basic questions that still remain. In addressing these questions, the authors feel it is important to seek solutions that emphasize physiological rather than mathematical significance. This approach leads to twin requirements for useful inverse solutions: accuracy, defined in a physiologically meaningful (and not just averaged and mathematical) sense, and reliability, not only to measurement noise but also to geometric modeling errors and other uncertainties that are inescapable in practical application. Studies using analytically tractable models may still be relevant, but it seems more important to find solutions to practical inverse problems, which will move the field toward wider acceptance and credibility View full abstract»

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  • Optically imaging cardiac activation with a laser system

    Page(s): 84 - 94
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    The authors have developed a laser imaging system that: 1) depicts potential distribution with high spatial and temporal resolution; 2) can image large areas; 3) does not require filtering for signal or image enhancement; 4) is flexible, allowing for the acquisition of images of programmable size and shape at varying frame rates; and 5) has a large depth of field, thus minimizing the loss of focus when simultaneously imaging areas of the heart at different distances from the prime focal plane. The high duality of the images obtained with this technique allows quantitative measurements to be made of both the potential distribution and the change in this distribution over time. Here, the authors discuss the components of the system and the present their experimental results View full abstract»

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  • Quantitative techniques for analyzing high-resolution cardiac-mapping data

    Page(s): 62 - 72
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    In high-resolution cardiac mapping, signals are simultaneously recorded from hundreds of electrodes in contact with the myocardium and then analyzed to reveal the underlying activation pattern. Activation mapping has a long history in both experimental and clinical cardiac electrophysiology and has also been used to study other organ systems. Much of the current emphasis in mapping technology is on data analysis-ways to extract useful information from the voluminous data stream-rather than on the acquisition of the data. Hence, in this article, the authors review the traditional method for analyzing and interpreting mapping data, isochronal mapping, and then report on additional techniques that have recently emerged. The authors focus on techniques applicable to quantifying the dynamics of complex tachyarrhythmias such as ventricular fibrillation (VF) and atrial fibrillation (AF) 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