By Topic

Date 25-28 Sept. 2005

Filter Results

Displaying Results 1 - 25 of 277
  • Computers in Cardiology

    Publication Year: 2005 , Page(s): 0_1
    Save to Project icon | Request Permissions | PDF file iconPDF (32 KB)  
    Freely Available from IEEE
  • Copyright page

    Publication Year: 2005 , Page(s): 0_2
    Save to Project icon | Request Permissions | PDF file iconPDF (71 KB)  
    Freely Available from IEEE
  • In memory of Christoph Zywietz (1937 - 2005)

    Publication Year: 2005 , Page(s): i
    Save to Project icon | Request Permissions | PDF file iconPDF (44 KB) |  | HTML iconHTML  
    Freely Available from IEEE
  • [Blank page]

    Publication Year: 2005 , Page(s): ii
    Save to Project icon | Request Permissions | PDF file iconPDF (23 KB)  
    Freely Available from IEEE
  • Computers in Cardiology 2005

    Publication Year: 2005 , Page(s): iii
    Save to Project icon | Request Permissions | PDF file iconPDF (25 KB)  
    Freely Available from IEEE
  • Introduction

    Publication Year: 2005 , Page(s): v
    Save to Project icon | Request Permissions | PDF file iconPDF (53 KB) |  | HTML iconHTML  
    Freely Available from IEEE
  • Rosanna Degani Young Investigator Award

    Publication Year: 2005 , Page(s): vi
    Save to Project icon | Request Permissions | PDF file iconPDF (82 KB)  
    Freely Available from IEEE
  • Table of contents

    Publication Year: 2005 , Page(s): vii - xxx
    Save to Project icon | Request Permissions | PDF file iconPDF (95 KB)  
    Freely Available from IEEE
  • Adaptive attenuation correction in contrast echo

    Publication Year: 2005 , Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (190 KB) |  | HTML iconHTML  

    Contrast echocardiography, as a tool for quantitative evaluation of left ventricular myocardial perfusion, has been the subject of massive research in the last few years. Nevertheless, this method is not in wide clinical use. Standard procedures derive the regional blood flow from the time-dependency of the echocardiographic videointensity within the myocardium. Thus, the data acquisition protocol tends to be lengthy (at least 5-6 sec). This is a serious problem, since the imaging plane must not change during the entire data acquisition. The present study presents a novel method, correcting for the signal attenuation in both the tissue and the contrast agent. It enables direct measurement of the local blood volume within the entire myocardium, based on a single heartbeat. Up until now, our technique has been tested on seven different patients, and shows high correlation between the automatically calculated perfusion levels and the segmental contractility View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Nearly automated left ventricular long axis tracking on real time three-dimensional echocardiographic data

    Publication Year: 2005 , Page(s): 5 - 8
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (403 KB) |  | HTML iconHTML  

    The measurement of left ventricular (LV) long axis length (LAL) is an integral part of echocardiographic evaluation of LV volume, the most important determinant of LV systolic function. LAL measurements from 2D echocardiography (2DE) are highly dependent on the ability to obtain non-foreshortened LV images. Real-time 3D echocardiography (RT3DE) could potentially overcome the effects of long-axis foreshortening, but LAL measurements on RT3DE data are currently based on manual analysis and are time-consuming. We developed and tested a nearly automated method based on optical flow techniques for the measurement of the LV LAL throughout the cardiac cycle from RT3DE data. Results of comparisons on 10 patients with manual tracing on RT3DE data showed good agreement and no significant bias (r=.99, bias=-1.8 mm). The proposed method allowed fast and accurate quantification of the LAL throughout the cardiac cycle with minimal user interaction and short computational time View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effect of body characteristics on thoracic attenuation of intra-cardiac electrical activity recorded on the surface electrocardiogram

    Publication Year: 2005 , Page(s): 9 - 12
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (121 KB) |  | HTML iconHTML  

    The objective of this study was to determine the effect of body characteristics on the electrical transfer function of the human thorax. Twenty patients undergoing electrophysiologic study were enrolled. Unipolar stimuli were applied in the right ventricular apical and posterioseptal areas. XYZ surface ECGs and unipolar intra-cardiac electrograms of the pacing impulses were recorded and signal-averaged. The intracardiac-to-surface transfer functions were modeled and compared with body characteristics. Physical dimensions, respiratory measures obtained by spirometry, and age correlated with magnitude intercepts and slopes of the modeled transfer functions in all three directions. The phase transfer functions were correlated with physical dimensions in the Y and Z directions. The effect of body characteristics on the frequency dependency of attenuation and phase has implications on the use of surface ECG and body surface mapping View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On the role of gap junctions in cardiac memory effect

    Publication Year: 2005 , Page(s): 13 - 16
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (104 KB) |  | HTML iconHTML  

    Memory in the nervous system is essentially a network effect, resulting from synaptic adaptation in a network of neurons. The heart too is a network of cardiac cells electrically coupled by gap junctions, which, we hypothesize, adapt as a function of the state of cellular depolarization. Cardiac memory, which refers to persistent effect of external stimulus on activation pattern, is demonstrated in a pair of model Noble cells with adaptive gap junctions. The memory seems to have a dual effect: while it dissipates small perturbations, it captures and imprints larger ones. The proposed memory mechanism is also shown to increase likelihood of synchronization among cardiac cells. Finally we argue that the proposed mechanism is linked to known electrophysiological properties of gap junctions View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Visualisation of cardiac wall motion using MR images

    Publication Year: 2005 , Page(s): 17 - 19
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (338 KB) |  | HTML iconHTML  

    Myocardial motion is a good indicator of coronary artery disease. In diagnosis relating to arterial disease and post infarct assessment it is important to view and study abnormal wall motion. In this paper we describe a Web-based visualization interface to view myocardial motion. We focus on using 4D cardiac MR images to analyze left ventricle wall motion. Using the interface it is possible to compare wall motion at different locations in the left ventricle to study abnormal behaviour. We consider our method to have a number of advantages, (i) The method uses MR datasets - which, by definition, are in 3-D and are acquired using non-ionizing radiation, (ii) The method works with any MR data set (i.e. from any scanner), (iii) Our user interface is fully Web-based and, hence, the images can be viewed at any location in the hospital View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • [Breaker page]

    Publication Year: 2005 , Page(s): 20
    Save to Project icon | Request Permissions | PDF file iconPDF (11 KB)  
    Freely Available from IEEE
  • Contour detection of short axis slice MR images for contraction irregularity assessment

    Publication Year: 2005 , Page(s): 21 - 24
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (132 KB) |  | HTML iconHTML  

    A new method for automatically detecting left ventricular endocardial borders in cardiac MRI short-axis slices was applied to a previously published patient group for which manually drawn contours already existed. An initial point lying in the left ventricular endocardium was found by a size invariant circular Hough transform. A coarse segmentation of the endocardial region was completed by merging surrounding regions and building the convex hull. Adjacent time frames were used to remove jitter from the contour movements. A feature (IRM), extracted from those contours, quantified the irregularities of left ventricular contractions. Patients with dilated cardiomyopathy were separated from the control group by thresholding the IRM parameter View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Quantitative assessment of the infarct transmurality using delayed contrast enhanced magnetic resonance images: description and validation

    Publication Year: 2005 , Page(s): 25 - 28
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (112 KB) |  | HTML iconHTML  

    The extent and degree of myocardial injury after an ischemic event are strong predictors of patient's outcome. After acute infarction, delayed contrast enhancement magnetic resonance imaging allows clinicians to distinguish between viable and non-viable myocardium and can delineate with high precision the infarcted tissue. The aim of this study is to provide a quantitative method based on the fuzzy c-means clustering algorithm to assess the location and the extent of the infarcted area. Segmental infarct trasmurality was visually assessed on a 5-point scale for the 288 segments. The agreement between visual and quantitative analyses was good: 84% of the segments were categorized similarly by quantitative and visual analyses View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An intuitive validation technique to comapre local versus global tagged MRI analysis

    Publication Year: 2005 , Page(s): 29 - 32
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (514 KB) |  | HTML iconHTML  

    Myocardium appears as a uniform tissue that seen in convectional Magnetic Resonance Images (MRI) shows just the contractile part of its movement. MR Tagging is a unique imaging technique that prints a grid over the tissue which moves according to the underlying movement of the myocardium revealing the true deformation of the cardiac muscle. Optical flow techniques based on spectral information estimate tissue displacement by analyzing information encoded in the phase maps which can be obtained using, local (Gabor) and global (HARP) methods. In this paper we compare both in synthetic and real Tagged MR sequences. We conclude that local method is slightly more accurate than the global one. On the other hand, global method is more efficient as it is much faster and less parameters have to be taken into account View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Regularization of phase contrast magnetic resonance images using optical flow and smoothness constraints

    Publication Year: 2005 , Page(s): 33 - 36
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1369 KB) |  | HTML iconHTML  

    This paper presents a post processing strategy for myocardial velocity fields obtained by phase contrast magnetic resonance imaging. Such data can be used to track cardiac motion and to calculate strain. The method combines data regularization with optical flow estimation to overcome the partial volume effect in the image acquisition. Validation is performed both in vitro and in vivo and it is shown that the method improves the accuracy of cardiac motion tracking View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Improved quantification of right ventricular volumes from cardiac magnetic resonance data

    Publication Year: 2005 , Page(s): 37 - 40
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (324 KB) |  | HTML iconHTML  

    Right ventricular (RV) volume quantification from cardiac magnetic resonance imaging is based on manual tracing of endocardial boundaries and application of geometric modeling. This procedure is subjective, time-consuming and may bias volume measurements since the right ventricle is a complex structure that is not well suited to a geometric model. We developed a technique for RV endocardial surface detection and direct volumes and ejection fraction (EF) quantification. Our technique was validated against conventional manual tracing and intra- and inter-observer variability were computed to test its reproducibility. Volumes and EF measurements showed high correlations with no significant biases and narrow limits of agreement compared to values derived from manual tracing. Intra- and inter-observer variability were smaller for the proposed method with respect to the reference technique. Our method resulted in fast, reliable and more reproducible measurements of RV volumes and EF when compared to conventional manual tracing View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A knowledge based home monitoring system for management and rehabilitation of cardiovascular patients

    Publication Year: 2005 , Page(s): 41 - 44
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (543 KB) |  | HTML iconHTML  

    A "managed care" model (prevention, diagnosis, therapy, admission, home assistance) has been realized to permit both a continuous patients check without hospitalization and a patients data archiving. An hardware and software architecture has been designed to manage the out-of-hospital treatments of patients with a moderate cardiovascular risk; as all the sensors built are wearable the cardio respiratory recording may have place during patients exercise program. Transmitted by wireless ECG has been automatically processed by "windows media center" through a multi parametric approach based on time and frequency (linear and non linear analysis) domain study. Advanced characteristics have been utilized by this monitoring prototype and different technologies, such as data acquisition, elaboration, on line transmission and Web-based data storage, have been integrated for knowledge management; in this way it is possible not only data real time visualization and collection but also a continuous patients management useful to improve life quality View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The effects of transmission errors in ECG real-timewavelet compression codecs

    Publication Year: 2005 , Page(s): 45 - 48
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (131 KB) |  | HTML iconHTML  

    This paper discusses the error effects in wavelet compression codecs for real-time ECG monitoring in a wireless telecardiology application. Two different strategies for ECG coding are presented and the error effects in the received ECG signals are discussed. Both quantitative (RMS error index) and qualitative (cardiologist opinions) are presented in order to decide if it is useful to monitor retrieved information from ECG packets received with errors or erroneous packets should be discarded. Although RMS index suggests that it would be recommendable to show them, cardiologists conditioned their preference to the number of erroneous blocks in the monitoring process: few number of errors, monitoring no information; high number of errors, monitoring erroneous information View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Telemedicine framework for manufacturer independent remote pacemaker follow-up

    Publication Year: 2005 , Page(s): 49 - 52
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1340 KB) |  | HTML iconHTML  

    Due to international standards each implantable cardiac pacemaker reacts to the application of a permanent magnet by changing the pacing rate in a predefined way depending on the depletion level of its battery. The purpose of this study has been to use a routine ECG recording to verify in a telemedicine framework whether the pacemaker works correctly or if further examination is indicated. The system has been implemented prototypically and has been evaluated in a clinical pilot trial on 24 consecutive patients with a total of 17 different pacemaker models from 6 different manufacturers. The promising results indicate that the presented follow-up concept, which can be handled by general practitioners, has the potential to work as an efficient screening method and may spare a significant number of patients the burden of having to travel to specialized hospitals which are often far away from patients' homes View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Remote transmission and analysis of signals from wearable devices in sleep disorders evaluation

    Publication Year: 2005 , Page(s): 53 - 56
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (435 KB) |  | HTML iconHTML  

    The aim of this work is to propose a new approach to traditional sleep monitoring, in order to simplify the acquisition and the managing of the signals and to reduce the patient's discomfort during data acquisition. Signals are collected by a sensorized garment and transmitted to a central elaboration station. The results of the elaboration are made available to the sleep specialist through a Web services organized Internet portal. The sleep specialist is able to review the data, to write and store in a database a diagnosis and to suggest a treatment for the patient. The employment of a sensorized garment drops down costs for installation and maintenance of a dedicated sleep monitoring center. Moreover, the Internet-based system proposed simplifies and speeds-up the retrieving and consulting of historical evidences View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Telemetric ECG evaluation using einthoven-leads

    Publication Year: 2005 , Page(s): 57 - 60
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (76 KB) |  | HTML iconHTML  

    A test data set consisting of 1264 ECGs is compared and evaluated by means of cross correlation with 24584 validated ECGs. The calculations are first carried out for all 12 medical leads and subsequently only for the 3 leads according to Einthoven. The aim of the investigation is to estimate the changes in the sensitivity and specificity between the 12-channel- and the 3-channel evaluation. Basis of the evaluations are the computed probability distributions for the classes of main diagnoses "ventricular hypertrophy", "myocardial infarction", "conduction disturbance" and "ischaemia". The results are checked in an blind test using the CSE test data set View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Multi-vendor solution for reception and review of ECGs to shorten treatment delay in AMI patients

    Publication Year: 2005 , Page(s): 61 - 63
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (366 KB) |  | HTML iconHTML  

    To provide optimal pre-hospital acute myocardial infarct (AMI) care, a system has been developed to receive ECGs from (ambulance) defibrillators from different manufacturers, and from ECG equipment in other hospitals or community medical centers. ECGs are sent as FAX to a special network-FAX, which forwards the received FAX (ECG) as E-mail attachment to a dedicated mailbox on the LUMC Microsoft Exchange mail server. Cardiologists and CCU nurses can view these e-mail messages (and thus the ECGs) to determine patient's eligibility for primary percutaneous coronary intervention (PCI), based on predefined criteria. If necessary the cardiologist on-call can view the ECG either in or outside the LUMC by logging on to the LUMC mail system. Between November 2004 and April 2005 ECGs from 209 patients (mean age: 62.3 yr, range 26-91 yr; 77.8% male) have been sent to the LUMC using this setup (136 ECGs from Medtronic defibrillators, 63 from Zoll defibrillators, 10 other) View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.