Download or read book ModelBased Approaches to Incorporate Recordings of Multiple Heartbeats Into the Inverse Problem of Electrocardiography written by Jaume Coll-Font and published by . This book was released on 2016 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: Solutions to the inverse problem of electrocardiography, also known as Electrocardiographic Imaging (ECGI), non-invasively image the electrical activity of the heart to localize and quantify normal and abnormal cardiac electrophysiology, and have recently attracted considerable attention in the research community. These methods have great promise to aid planning of catheter ablation procedures as well as for screening and diagnosis. They solve a problem that uses electrocardiographic measurements on the body surface (ECGs) to characterize the unknown electrical activity of the heart, here described by the time series of distribution of electrical potential on the heart surface. To do so, they rely on the calculation of a "forward" model relating the potentials on the heart with the ECGs, typically known as "forward matrix". However, ECGI has some limitations that impede its application to routine clinical practice. One of them is the ill-posedness of the forward model, which causes inverse solutions to be unreliable even with small levels of noise in the inputs and the model. One way of improving the resilience to this problem is to increase the Signal to Noise Ratio (SNR) of the signal by the incorporation of recordings from multiple heartbeats. During the course of this thesis we have addressed this approach in several applications: imaging the presence of T-wave alternans on the heart, localizing the site of earliest activation of pre-ventricular contractions (PVC) and the characterization of the errors introduced in the forward matrix. T-wave alternans (TWA), defined as a beat-to-beat alternation of the T-wave in the ECG, have been advocated for the past two decades as a promising marker of susceptibility to sudden cardiac death (SCD). However current ECG tests for TWA have been reported to have high sensitivity but low specificity for SCD and thus there is still no consensus on their predictive value. The distinction between concordant alternans---for which the whole heart alternates at the same phase---and discordant alternans---for which different regions of the heart alternate in different magnitude and phase---is of special interest as the latter have been observed preceding ventricular fibrillation in animal experiments and simulations. Thus, better characterization of the spatial behavior of discordant alternans could lead to improvements in the predictive value of TWA tests. Motivated by the desire to identify and localize discordant regions from body surface measurements, we present two studies related to TWA. In the first we introduce a theoretical characterization of how concordant and discordant alternans appear on the body surface. In the second study we present a method that directly estimates the location and phase of discordant TWA on the heart surface from body surface measurements by combining techniques from TWA detection with the methodology of ECGI. The results obtained with both studies on TWA suggest considerable promise that these methods may help increase our ability to understanding TWA based on body surface recordings, and thereby more clearly study its link to SCD, by providing previously unavailable spatial information to researchers and clinicians. Accurate detection of the site of first activation in a pre-ventricular contraction (PVC) can lead to substantial improvements in pre-procedure planning for ablation interventions and the subsequent reduction length and costs of these interventions. However, to be able to accurately localize these sites, it is necessary to obtain reliable inverse reconstructions of the activation wavefront that propagates throughout the heart during QRS. In this thesis, we present two approaches to increase the SNR through the incorporation of multiple recordings from the same underlying PVC activity. In the first one, we study deterministic averaging approaches to incorporate multiple heartbeats in an inverse solver. In the second one, we extend the previous averaging approaches into a statistically inspired model to characterize the beat-to-beat fluctuations observed on the ECG. These studies showed some improvement over regular averaging techniques, but the beat-to-beat variability still present in the solutions suggested that there is need to better characterize the sources of noise, which led to the third contribution of this thesis. Model mismatch in the forward matrix is a significant factor in inverse solution error. This is particularly problematic when incorporating multiple heartbeat recordings, as the heart moves within the thorax from beat to beat due to respiration. Therefore, the use of a single forward matrix necessarily introduces model errors in this setting. To overcome this limitation, we propose in this work to efficiently characterize the changes in the forward matrix due to movements of the heart and then adapt the forward matrix to each individual heartbeat. With that objective we developed a new method to characterize errors in the forward matrix that are produced by movement of the heart. This method approximates the changes in volume conductor geometry with a parameterized transform and then encapsulates the forward matrices that these changes would generate into a single mapping function that describes the whole sequence of computations. With this mapping, it is then possible to apply optimization methods that correct for the errors in the forward matrix, generating an approximate forward matrix corresponding to an estimated position and orientation of the heart and, if desired, also solve for the unknown cardiac electrical potentials in an iterative fashion. We expect this work to impact ECGI research and beyond. In ECGI, we expect to improve results in animal models used for understanding mechanisms and validating inverse solutions and to reduce uncertainty of inverse solutions obtained in clinical applications, and to expand the range of potential clinical problems for which ECGI can be reasonably applied by reducing the need for extensive high resolution anatomical imaging. Beyond ECGI, the capacity to non-invasively track the position of the heart has the potential to impact a number of other clinical problems, for example, improving catheter registration in ablation procedures.
Download or read book Electrocardiographic Imaging written by Maria S. Guillem and published by Frontiers Media SA. This book was released on 2020-04-17 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electrical activity in the myocardium coordinates the contraction of the heart, and its knowledge could lead to a better understanding, diagnosis, and treatment of cardiac diseases. This electrical activity generates an electromagnetic field that propagates outside the heart and reaches the human torso surface, where it can be easily measured. Classical electrocardiography aims to interpret the 12-lead electrocardiogram (ECG) to determine cardiac activity and support the diagnosis of cardiac pathologies such as arrhythmias, altered activations, and ischemia. More recently, a higher number of leads is used to reconstruct a more detailed quantitative description of the electrical activity in the heart by solving the so-called inverse problem of electrocardiography. This technique is known as ECG imaging. Today, clinical applications of ECG imaging are showing promising results in guiding a variety of electrophysiological interventions such as catheter ablation of atrial fibrillation and ventricular tachycardia. However, in order to promote the adoption of ECG imaging in the routine clinical practice, further research is required regarding more accurate mathematical methods, further scientific validation under different preclinical scenarios and a more extensive clinical validation
Download or read book Computational Inverse Problems in Electrocardiography written by Peter Johnston and published by WIT Press (UK). This book was released on 2001 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: The inverse problem of electrocardiography is an important issue in the diagnosis of cardiac electrical conduction defects and other cardiac related health issues. An accurate solution to this problem provides an important addition to methods of pinpointing regions of tissue damage following acute myocardial infarction or establishing the sites of ectopic beats. However, before such technology can be placed in the hands of clinicians, considerable developmental work must be performed in the areas of applied mathematics, computation, physics and engineering.
Download or read book Application of Lead Field Theory and Computerized Thorax Modeling for the ECG Inverse Problem written by and published by . This book was released on 2001 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ECG inverse problem is a widely studied area, and several different approaches have been used to solve II. The present study introduces the reciprocally calculated lead field concept for solving the ECG inverse problem. The lead field approach based on the reciprocity theorem provides a procedure to calculate the computationally heavy forward problem by a single solution for each ECG lead. In this study, one anatomically detailed 3D FDM model of the human thorax as a volume conductor was employed for forward and inverse estimation of ECG potentials and cardiac sources, respectively. Several equivalent dipole sources were set into the cardiac muscle and the surface potential distributions applying 12, 24, 32, 64, and 120-lead ECG electrode configurations were computed. The inverse problem was solved in order to localize the dipoles based on the information obtained from the simulated ECG recordings and the characteristics of the volume conductor. The dipole localization errors ranged from 2 to 5 mm depending on the number of electrodes. Thus, the lead field method appears to be applicable for the solution of the ECG inverse problem.
Download or read book Functional Imaging and Modeling of the Heart written by Olivier Bernard and published by Springer Nature. This book was released on 2023-06-15 with total page 735 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book constitutes the refereed proceedings of the 12th International Conference on Functional Imaging and Modeling of the Heart, held in Lyon, France, in June 2023. The 72 full papers were carefully reviewed and selected from 80 submissions. The focus of the papers is on following topics: increased imaging resolutions, data explosion, sophistication of computational models and advent of AI frameworks, while new imaging modalities have emerged (e.g. combined PET-MRI, Spectral CT).
Download or read book Cardiology Explained written by Euan A. Ashley and published by Remedica. This book was released on 2004 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the most time-consuming tasks in clinical medicine is seeking the opinions of specialist colleagues. There is a pressure not only to make referrals appropriate but also to summarize the case in the language of the specialist. This book explains basic physiologic and pathophysiologic mechanisms of cardiovascular disease in a straightforward manner, gives guidelines as to when referral is appropriate, and, uniquely, explains what the specialist is likely to do. It is ideal for any hospital doctor, generalist, or even senior medical student who may need a cardiology opinion, or for that ma.
Download or read book The Engineering Index Annual written by and published by . This book was released on 1992 with total page 2264 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since its creation in 1884, Engineering Index has covered virtually every major engineering innovation from around the world. It serves as the historical record of virtually every major engineering innovation of the 20th century. Recent content is a vital resource for current awareness, new production information, technological forecasting and competitive intelligence. The world?s most comprehensive interdisciplinary engineering database, Engineering Index contains over 10.7 million records. Each year, over 500,000 new abstracts are added from over 5,000 scholarly journals, trade magazines, and conference proceedings. Coverage spans over 175 engineering disciplines from over 80 countries. Updated weekly.
Download or read book Index Medicus written by and published by . This book was released on 2002 with total page 1948 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Cumulated Index Medicus written by and published by . This book was released on 1989 with total page 1470 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advanced Methods and Tools for ECG Data Analysis written by Gari D. Clifford and published by Artech House Publishers. This book was released on 2006 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt: This practical book is the first one-stop resource to offer a thorough, up-to-date treatment of the techniques and methods used in electrocardiogram (ECG) data analysis, from fundamental principles to the latest tools in the field. The book places emphasis on the selection, modeling, classification, and interpretation of data based on advanced signal processing and artificial intelligence techniques.
Download or read book Proceedings of the 20th Annual International Conference of the IEEE Engineering in Medicine and Biology Society written by IEEE Engineering in Medicine and Biology Society. Annual Conference and published by Institute of Electrical & Electronics Engineers(IEEE). This book was released on 1998 with total page 572 pages. Available in PDF, EPUB and Kindle. Book excerpt: These proceedings document the 20th Annual International Conference of the IEEE/EMB Society held in Amsterdam in 1998. Covering the entire field of biomedical including the latest development in instrumentation, neourotechnology, rehabilitation engineering, imaging signal & image processing, cardiac system, neuromuscular system, sensory systems, physiological system modeling, measurement techniques, clinical engineering & tissue engineering. Partial Contents: Cardiovascular Systems; Medical Imaging; Clinical Engineering; Medical Informatics; Signal Processing; Neuromuscular Systems; Biomechanics; Physiological Systems; Modeling & Identification; Instrumentation
Download or read book Mathematically Modelling The Electrical Activity Of The Heart From Cell To Body Surface And Back Again written by Pullan Andrew and published by World Scientific Publishing Company. This book was released on 2005-09-07 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book on modelling the electrical activity of the heart is an attempt to describe continuum based modelling of cardiac electrical activity from the cell level to the body surface (the forward problem), and back again (the inverse problem). Background anatomy and physiology is covered briefly to provide a suitable context for understanding the detailed modelling that is presented herein. The questions of what is mathematical modelling and why one would want to use mathematical modelling are addressed to give some perspective to the philosophy behind our approach. Our view of mathematical modelling is broad — it is not simply about obtaining a solution to a set of mathematical equations, but includes some material on aspects such as experimental and clinical validation.
Download or read book Transdisciplinary Engineering Methods for Social Innovation of Industry 4 0 written by M. Peruzzini and published by IOS Press. This book was released on 2018-09-14 with total page 1250 pages. Available in PDF, EPUB and Kindle. Book excerpt: The concept of concurrent engineering (CE) was first developed in the 1980s. Now often referred to as transdiciplinary engineering, it is based on the idea that different phases of a product life cycle should be conducted concurrently and initiated as early as possible within the Product Creation Process (PCP). The main goal of CE is to increase the efficiency and effectiveness of the PCP and reduce errors in later phases, as well as incorporating considerations – including environmental implications – for the full lifecycle of the product. It has become a substantive methodology in many industries, and has also been adopted in the development of new services and service support. This book presents the proceedings of the 25th ISPE Inc. International Conference on Transdisciplinary Engineering, held in Modena, Italy, in July 2018. This international conference attracts researchers, industry experts, students, and government representatives interested in recent transdisciplinary engineering research, advancements and applications. The book contains 120 peer-reviewed papers, selected from 259 submissions from all continents of the world, ranging from the theoretical and conceptual to papers addressing industrial best practice, and is divided into 11 sections reflecting the themes addressed in the conference program and addressing topics as diverse as industry 4.0 and smart manufacturing; human-centered design; modeling, simulation and virtual design; and knowledge and data management among others. With an overview of the latest research results, product creation processes and related methodologies, this book will be of interest to researchers, design practitioners and educators alike.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1991 with total page 1102 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electrical Electronics Abstracts written by and published by . This book was released on 1997 with total page 2304 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Documentation Abstracts written by and published by . This book was released on 1992 with total page 760 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Methods in Social Neuroscience written by Eddie Harmon-Jones and published by Guilford Press. This book was released on 2012-05-09 with total page 371 pages. Available in PDF, EPUB and Kindle. Book excerpt: Straightforward and practical, this is the first book to provide detailed guidance for using neurobiological methods in the study of human social behavior, personality, and affect. Each chapter clearly introduces the method at hand, provides examples of the method's applications, discusses its strengths and limitations, and reviews concrete experimental design considerations. Written by acknowledged experts, chapters cover neuroimaging techniques, genetic measurement, hormonal methods, lesion studies, startle eyeblink responses, facial electromyography, autonomic nervous system responses, and modeling based on neural networks.
