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Date 26-29 Sept. 2010

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Displaying Results 1 - 25 of 286
  • [Front cover]

    Page(s): c2
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  • [Copyright notice]

    Page(s): ii
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  • Board of directors

    Page(s): iii
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  • Editor

    Page(s): iv
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  • 2010 organizing committee

    Page(s): v - vi
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  • Introduction

    Page(s): vii
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  • Rosanna Degani Young Investigator Award

    Page(s): viii
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  • Table of contents

    Page(s): ix - xxxiv
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  • MRI-based quantification of myocardial perfusion at rest and stress using automated frame-by-frame segmentation and non-rigid registration

    Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (278 KB) |  | HTML iconHTML  

    We developed a method for automated quantification of myocardial perfusion from cardiac magnetic resonance (CMR) images. Our approach uses region-based and edge-based level set techniques for endocardial and epicardial border detection combined with non-rigid registration achieved by a 2D multi-scale cross-correlation and contour adaptation. This method was tested on 66 short-axis image sequences (Philips 1.5T) obtained in 11 patients at rest and during vasodilator stress at 3 levels of the left ventricle during first pass of a Gadolinium-DTPA bolus. Myocardial ROIs were automatically defined and contrast enhancement curves were constructed throughout the image sequence. Analysis of one sequence required <;1 min and resulted in endo- and epicardial boundaries that were judged accurate. Curves obtained during stress showed the typical pattern of first-pass perfusion with SNR of 19±4, as well as increased contrast inflow rate (0.031±0.013 vs 0.014±0.004 sec-1) and higher peak-to-peak amplitude (0.20±0.05 vs 0.14±0.03) compared to resting curves. Despite the extreme dynamic nature of contrast enhanced image sequences and respiratory motion, fast automated detection of myocardial segments and quantification of tissue contrast results in time curves with excellent noise levels, which reflect the expected effects of stress. View full abstract»

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  • Correlation between time domain baroreflex sensitivity and Sympathetic Nerve Activity

    Page(s): 5 - 8
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (320 KB) |  | HTML iconHTML  

    Autonomic nervous system (ANS) dysfunction is evidenced by reduced baroreflex sensitivity (BRS), which can be quantified as the slope between SBP and RR values in baroreflex events (BEs). BEs can be either of short or of long length, so they are likely to be associated with fast/parasympathetic as well as with slow/sympathetic ANS modulations. Under sympathetic inhibition, LF power in Muscle Sympathetic Nerve Activity (MSNA) decreases and HF power dominates. Therefore, it is suggested that LF and HF powers of MSNA are related with sympathetic neural excitation and inhibition, respectively. In this work, MSNA powers are associated with BRS from short/long BEs, defined from a cutoff length estimated from the respiratory frequency of each subject. The results indicate that BRS from short(long) BEs are correlated with HF(LF), while not significantly correlated with LF(HF) powers. Therefore, short and long BEs may carry different information on ANS modulations in baroreflex regulation. View full abstract»

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  • Fully automated gating of optical coherence tomography data

    Page(s): 9 - 12
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (396 KB) |  | HTML iconHTML  

    Intra-coronary optical coherence tomography (OCT) provides ultra-high resolution imaging of coronary vessel wall structures. However, during image acquisition the OCT catheter is affected by cardiac motion. These motion-induced artifacts not only complicate longitudinal image reconstructions, it results in a saw-tooth shaped appearance of the coronary vessel wall, but more importantly it affects the accuracy of quantitative analysis (QOCT). To overcome this problem we propose to perform image-based gating applying a genetic algorithm (GA) that automatically selects a subset of OCT cross-sections that are relatively unaffected by the catheter displacement during the cardiac cycle. The gated subset contains cross-sections (frames) acquired in the near end-diastolic phase, during which the heart is relatively motionless. We evaluated the GA in a comparison test with a different gating method (Simulated Annealing (SA)) and with manual frame selection (MFS) and found promising results. View full abstract»

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  • Simulating the impact of the transmural extent of acute ischemia on the electrocardiogram

    Page(s): 13 - 16
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (8508 KB) |  | HTML iconHTML  

    During acute cardiac ischemia, electrophysiological properties of the affected tissue are altered in the subendo-cardium firstly. If the occlusion worsens, the effects spread transmurally. Diagnosis of cardiac ischemia, which should be improved by computer simulations, is based on shifts of the ST segment. In this work, we simulated heterogeneous ischemic regions with varying transmural extent. The excitation propagation and ECGs were calculated for the different setups. We showed that ST segment polarity can be dependent on the transmural extent of the ischemic region. In case of subendocardial ischemia, short action potentials were initiated in the ischemic zone causing a slight transmural gradient of the transmembrane voltage. Therefore, the ST segment was depressed in leads near the ischemic region in the chosen case. During transmural ischemia, this gradient showed in the opposite direction from epicardium to endocardium leading to ST segment elevation. View full abstract»

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  • Development and comparison of single-parameter indices characterizing severity of acute myocardial ischemia

    Page(s): 17 - 20
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (383 KB) |  | HTML iconHTML  

    Our aim was to assess the sensitivity/specificity of 2 indices of ischemia severity (Σ|ST| and STRMS) for 5 triplets of leads: X, Y, Z; V2, V5, aVF; V2, V5, III; V3, V5, III; and V3, V6, III, each derived from 7 subsets of Mason-Likar 12-lead ECG with limb leads and dual precordial leads (V1, V3; V1, V4; V1, V5; V2, V4; V2, V5; V3, V5; V3, V6). Coefficients for deriving lead triplets were developed from the design set (n = 892). The test set comprised 12-lead ECGs (n = 99) acquired before and during ischemia induced by balloon-inflation angioplasty. We compared the ability of tested indices to detect ischemia by constructing their receiver operating characteristics (ROCs) and measuring a percentage area under the entire ROC curve (AUC) and in specificity range 0.8-0.9 (AUC0.8-0.9). The mean performance for 7 predictor sets in terms of AUC (%) for Σ|ST|/STRMS was: 88.4/88.8 for X, Y, Z; 88.6/86.5 for V2, V5, aVF; 89.4/87.5 for V2, V5, III; 90.4/90.3 for V3, V5, III; and 90.5/90.2 for V3, V6, III. Mean values of AUC0.8-0.9 (%) for Σ|ST|/STRMS were: 78.1/80.5 for X, Y, Z; 80.7/71.6 for V2, V5, aVF; 77.6/74.5 for V2, V5, III; 77.7/80.8 for V3, V5, III; and 85.7/82.4 for V3, V6, III. Thus we conclude that the currently used indices using “pseudo-orthogonal” leads V2, V5, aVF, and orthogonal leads X, Y, Z performed in ischemia detection nearly as the best indices based on V3, V6, III. These results should be corroborated on a larger study population. View full abstract»

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  • Validation of electrocardiographic criteria for predicting the culprit artery in patients with acute myocardial infarction

    Page(s): 21 - 24
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (147 KB) |  | HTML iconHTML  

    In this study we compare a variety of ECG criteria for predicting the culprit artery in cases with ST-segment elevation myocardial infarction (STEMI). We also assess the performance of these criteria for patients who did not meet the STEMI criteria although having an acute myocardial infarction (AMI). View full abstract»

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  • A spatio-temporal study of ischemia and the time-frequency coupling variations between the ST amplitude, heart rate and dominant angle

    Page(s): 25 - 28
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (643 KB) |  | HTML iconHTML  

    An analysis of the Long Term ST Database (LTSTDB) was conducted to quantify the spatio-temporal dynamics of ischemic and non-ischemic episodes. For all 86 recordings the ischemic episode length is described by a lognormal distribution and the non-ischemic episode length by a generalized extreme value distribution. For the 15 recordings that possess orthogonal (EASI) leads sets we derived the 12 standard leads and analyzed the spatial time course (from the j-point to j+120 ms) of each episode over time to identify dominant trends. Although the magnitude of the ischemic episodes did not reveal any inter-subject trend (except for generally exhibiting Brownian-like motion), there appeared to be strong correlations with the heart rate (HR). Wavelet cross-spectral coupling with significance testing was then applied to the ST-amplitude and HR evolution over the course of each episode. In all subjects significant cross-spectral correlations were found at very low frequencies (<;0.04 Hz), as well as at respiration and baroreflex frequencies. This may indicate that the ischemic episodes are modulated by blood pressure and activity or HR-related phenomena and that all episodes in the LTSTDB may be of a `mixed' type at some point in their duration. The dominant angle also showed significant correlation (p<;0.01) with the ST amplitude and HR changes at similar frequencies to those described above. All three protocols used to define ischemia in the LTSTDB gave similar results. View full abstract»

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  • Evaluating enhancing the acute myocardial infarction criteria in the Glasgow electrocardiogram analysis program by including ST depression

    Page(s): 29 - 32
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (137 KB) |  | HTML iconHTML  

    The aims of this study were to investigate if the acute myocardial infarction (MI) criteria in the University of Glasgow ECG analysis program (Uni-G) could be enhanced by including new lead pairings and to explore alternative criteria based on STEMI equivalence. 912 12-lead ECGs were recorded in ambulances on patients with a suspected acute coronary syndrome. The ACC/ESC and the Uni-G criteria were modified to include pairings {III,-aVL}, {-III,aVL}, and {-V2,-V3}. Using the hospital discharge diagnosis as the gold standard, the modified criteria were evaluated. Significant changes in sensitivity (SE) and specificity (SP) were evident using the modified ACC/ESC criteria: SE from 72.1% to 75.4% (p=0.002); SP from 88.1% to 86.6% (p=0.004). The current Uni-G criteria gave better results than the modified ACC/ESC criteria (SE 77.6% and SP 93.9%.). All attempts at extending the Uni-G criteria resulted in a decrease in SP. View full abstract»

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  • Graphic visualization of ECG estimated myocardial infarct size using the standardized seventeen segment bull's eye plot

    Page(s): 33 - 36
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (10528 KB) |  | HTML iconHTML  

    The bull's eye plot has been successfully introduced in multiple cardiac imaging diagnostic modalities and standardized by AHA in recent years. The ECG estimated myocardial infarct (MI) size is a quantitative measure of the size of the infarct region in left ventricular myocardium and is a proven tool to assist cardiologists in clinical decision making. MI size has been presented as a percentage of the left ventricle (LV) mass based on Selvester ECG scoring system. The scoring system has 50 ECG criteria with corresponding points. The reported MI size is not associated with a specific location in LV. This study applied the Selvester scoring system and bull's eye plot to create a quantitative MI size presentation with visual location in the LV. The automated Selvester scoring algorithm was validated using a database of 688 ECGs with and without MI. The automated ECG-MI size was tested against two cardiologists' manual scores resulting in 94% correlation. View full abstract»

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  • Heart-surface potentials estimated from 12-lead electrocardiograms

    Page(s): 37 - 40
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (239 KB) |  | HTML iconHTML  

    We investigated whether the ischemic region due to coronary-artery occlusion can be visualized on the heart-surface display by using as input data just ST measurements from the 12-lead ECG. A boundary-element torso model was used to estimate heart-surface potentials from body-surface potential maps (BSPMs) obtained from 12-lead ECG via transformation developed from a design set (n = 892) of 120-lead ECGs by a least-square solution to the linear regression problem. The test set consisted of 120-lead ECGs acquired for 45 patients during ischemia induced by balloon-inflation angioplasty; subgroups of equal size consisted of patients whose LAD, LCx, and RCA were occluded, respectively. BSPMs at J point of each patient were predicted from the 12-lead ECG and similarity of original and predicted maps was assessed by a similarity coefficient SC (0-100%). By inverse solution, heart-surface potentials were then estimated from original and predicted BSPMs and visualized on a bull's-eye display. Reconstitution of known BSPMs from the 12-lead ECG achieved an overall SC 92.46 ± 6.95% (mean ± SD); for subgroups, SC was: 89.79 ± 9.95% for LAD, 93.89 ± 2.86% for LCx, and 93.70 ± 5.77% for RCA group. Estimated heart-surface potential distributions featured an area of positive potentials corresponding, in general, to the underperfused territory caused by the occlusion. Encouraging results can be attributed to the strongly dipolar character of BSPMs caused by injury current. This approach shows promise for ischemia detection and quantitation. View full abstract»

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  • An augmentative and portable QTc-Observer(QTO-Q2) to facilitate more purposeful outpatient monitoring

    Page(s): 41 - 44
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (189 KB) |  | HTML iconHTML  

    A tele-medical approach for monitoring and detecting prolonging QT-intervals via cellular equipments is proposed in this paper. Currently, the procedures for detecting Longed QT Syndrome (LQTS) involves taking a 1 time preliminary prognosis followed by a comprehensive long time hospital or laboratory bound monitoring; the latter is only conducted if and only if the former is tested positive. However, if the preliminary prognosis fails due to the absence of the symptoms during the instance of testing, the subject may be declared with a false clean bill of health. In this modern day and age where telemedicine is becoming a more important aspect of conventional medicine, it is sensible that the conventional methods be augmented with ambulatory long-term monitoring to better detect LQTS for people suspected of it. The QTc-Observer (QTO or Q2) is developed to monitor specifically QT intervals for the detection of LQTS. Built on top of the existing MobiCare System [1] and a newly developed QT/QTc trend interval measure algorithm [2], the Q2 is connected to an all-day monitoring center for continuous observations by medical professionals. View full abstract»

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  • Non-invasive sensors based human state in nightlong sleep analysis for home-care

    Page(s): 45 - 48
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (149 KB) |  | HTML iconHTML  

    In this paper we present methodology used in a non-invasive, easy-to-use and low-cost monitoring system for nightlong human sleep quantification. Our system uses simultaneous measurement of three different signals representing the activity of the human body: infrared video-recorded subject motion, audio-recorded acoustic effects and the three-leads electrocardiogram. Signal-specific interpretation methods yield parameters selected as most discriminative for the sleep quality, synchronized and combined as a sleep record. In the experimental stage the nightlong sleep was supervised by the reference EEG recordings and particular components of the sleep record were correlated to the presence of delta wave representing deep sleep. Significant correlation values in most subjects allow to validate the proposed sleep record as comparable to the standard polysomnogram. View full abstract»

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  • Management of non-uniform data transfer in cardiac monitoring systems with adaptive interpretation

    Page(s): 49 - 52
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (81 KB) |  | HTML iconHTML  

    Our research concerns the problem of data queuing in telemedical non-uniformly reporting surveillance systems, recently introduced to cardiology. Automatic scheduling of reports was achieved with taking into consideration of two auxiliary data attributes in the information structure: the validity period and the priority, set individually for each ECG diagnostic measurement. The patient-side recorder-interpreter works in one of two reporting modes: in the delayed mode the transmission is deferred until packets are filled with valid data, while in the immediate mode diagnostic packets are transmitted as promptly as implied by sampling requirements. In the delayed reporting mode, the packet size lasts for 6 minutes of recording, while the wireless transfer session is completed within 10 seconds, allowing for reduction of 94% of required power. In the immediate reporting mode, the packet is collected within 4.63 seconds, which is still acceptable as real time monitoring. View full abstract»

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  • Optimization of the alarm-management of a heart failure home-monitoring system

    Page(s): 53 - 56
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (138 KB) |  | HTML iconHTML  

    In the present study we show how an algorithm for generating heart failure alerts can be improved by retrospectively evaluating the available data. We built on a previous study on home based monitoring of heart failure patients after an episode of acute decompensations using mobile phones. Data from patients monitored in the years 2003 to 2008 were analyzed. For the analysis of historic treatment and measurement tables, GNU-R statistical software was used. A data processing algorithm was implemented to optimize the alarm-management of the heart failure home-monitoring system. The improvement was achieved by reducing the number of generated false alarms and by introducing a risk parameter, which could be used to indicate the patient's status. The algorithm provided adequate sensitivity and specificity and showed a significant improvement to the previous model, reducing the number of false alarms. View full abstract»

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  • Multimedia paging for clinical alarms on mobile platforms

    Page(s): 57 - 60
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (122 KB) |  | HTML iconHTML  

    In the intensive care setting patient monitors generate many alarms. These alarms are frequently benign, but also unobserved as the caregiver is not at the location where the alarm is delivered. We developed a web-interface, integrated with an alarm manager that provides access to the “patient event” data. Alarm messages can be displayed by care unit and patient. Vital signs at the moment of the “patient event”, as well as before and after can be displayed. The interface is compatible with the main Smartphone platforms (iPhone, Android, Blackberry, Windows Mobile and Symbian) and may facilitate a faster, more adequate response by caregivers to patient monitor alarms. View full abstract»

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  • Evaluation of patient adherence and satisfaction with a self-measurement blood pressure telemonitoring program

    Page(s): 61 - 64
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (131 KB) |  | HTML iconHTML  

    The aim of this study was to evaluate the patients adherence and satisfaction with a self-measurement blood pressure telemonitoring program. The study enrolled patients dismissed from a health structure after the acute phase of a major cardiac or cerebro-vascular event. At dismission each patient received a telemedicine system equipped with an automatic blood pressure device, and an evaluation questionnaire. 17 patients were monitored for an average of 75 days each. 16 out of 17 participants completed the feedback questionnaire. All patients (100%) scored installation, usability and quality of service as “good” or “very good”. The majority of patients (13 out of 16) declared to feel comfortable with the self-measurement of blood pressure and the use of the telemonitoring system. Telemonitoring of blood pressure measurement can be considered a mature technology which find favour with patients dismissed after a acute cardiac or cerebro-vascular event. View full abstract»

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  • Heart rate variability characterized by Refined Multiscale Entropy applied to cardiac death in ischemic cardiomyopathy patients

    Page(s): 65 - 68
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (99 KB) |  | HTML iconHTML  

    In this work, Refined Multiscale Entropy (RMSE) was applied to characterize risk of cardiac death in ischemic cardiomyopathy patients, analyzing heart rate variability (HRV) by means of RR series during daytime and nighttime. RMSE approach measures an entropy rate in different time scales of a series, giving a multiscale characterization of complexity of that series. RMSE showed statistically significant differences (p<;0.05) during daytime and nighttime only in middle time scales (τ=4-15 and τ=3-16, respectively). For these scales, RMSE was higher in low risk (SV) than in high risk (CM) group of cardiac death, indicating a reduction of the entropy-based complexity in CM when it was compared with SV. No statistical differences between risk groups were presented at time scale τ=1 (unfiltered original RR series). It can be concluded that the dynamics in middle time scales should be considered to better describe the HRV of patients with cardiac death. View full abstract»

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