Ikaro Silva, Joachim Behar, Reza Sameni, Tingting Zhu, Julien Oster, Gari D Clifford, George B Moody
{"title":"Noninvasive Fetal ECG: the PhysioNet/Computing in Cardiology Challenge 2013.","authors":"Ikaro Silva, Joachim Behar, Reza Sameni, Tingting Zhu, Julien Oster, Gari D Clifford, George B Moody","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The PhysioNet/CinC 2013 Challenge aimed to stimulate rapid development and improvement of software for estimating fetal heart rate (FHR), fetal interbeat intervals (FRR), and fetal QT intervals (FQT), from multichannel recordings made using electrodes placed on the mother's abdomen. For the challenge, five data collections from a variety of sources were used to compile a large standardized database, which was divided into training, open test, and hidden test subsets. Gold-standard fetal QRS and QT interval annotations were developed using a novel crowd-sourcing framework. The challenge organizers used the hidden test subset to evaluate 91 open-source software entries submitted by 53 international teams of participants in three challenge events, estimating FHR, FRR, and FQT using the hidden test subset, which was not available for study by participants. Two additional events required only user-submitted QRS annotations to evaluate FHR and FRR estimation accuracy using the open test subset available to participants. The challenge yielded a total of 91 open-source software entries. The best of these achieved average estimation errors of 187bpm<sup>2</sup> for FHR, 20.9 ms for FRR, and 152.7 ms for FQT. The open data sets, scoring software, and open-source entries are available at PhysioNet for researchers interested on working on these problems.</p>","PeriodicalId":72683,"journal":{"name":"Computing in cardiology","volume":"40 ","pages":"149-152"},"PeriodicalIF":0.0,"publicationDate":"2013-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4230703/pdf/nihms582730.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32818118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Brett M Burton, Burak Erem, Kristin Potter, Paul Rosen, Chris R Johnson, Dana H Brooks, Rob S Macleod
{"title":"Uncertainty Visualization in Forward and Inverse Cardiac Models.","authors":"Brett M Burton, Burak Erem, Kristin Potter, Paul Rosen, Chris R Johnson, Dana H Brooks, Rob S Macleod","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Quantification and visualization of uncertainty in cardiac forward and inverse problems with complex geometries is subject to various challenges. Specific to visualization is the observation that occlusion and clutter obscure important regions of interest, making visual assessment difficult. In order to overcome these limitations in uncertainty visualization, we have developed and implemented a collection of novel approaches. To highlight the utility of these techniques, we evaluated the uncertainty associated with two examples of modeling myocardial activity. In one case we studied cardiac potentials during the repolarization phase as a function of variability in tissue conductivities of the ischemic heart (forward case). In a second case, we evaluated uncertainty in reconstructed activation times on the epicardium resulting from variation in the control parameter of Tikhonov regularization (inverse case). To overcome difficulties associated with uncertainty visualization, we implemented linked-view windows and interactive animation to the two respective cases. Through dimensionality reduction and superimposed mean and standard deviation measures over time, we were able to display key features in large ensembles of data and highlight regions of interest where larger uncertainties exist.</p>","PeriodicalId":72683,"journal":{"name":"Computing in cardiology","volume":"40 ","pages":"57-60"},"PeriodicalIF":0.0,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4221850/pdf/nihms551351.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32803931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ikaro Silva, George Moody, Daniel J Scott, Leo A Celi, Roger G Mark
{"title":"Predicting In-Hospital Mortality of ICU Patients: The PhysioNet/Computing in Cardiology Challenge 2012.","authors":"Ikaro Silva, George Moody, Daniel J Scott, Leo A Celi, Roger G Mark","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Acuity scores, such as APACHE, SAPS, MPM, and SOFA, are widely used to account for population differences in studies aiming to compare how medications, care guidelines, surgery, and other interventions impact mortality in Intensive Care Unit (ICU) patients. By contrast, the focus of the PhysioNet/CinC Challenge 2012 is to develop methods for patient-specific prediction of in-hospital mortality. The data used for the challenge consisted of 5 general descriptors and 36 time series (measurements of vital signs and laboratory results) from the first 48 hours of the first available ICU stay of 12,000 adult patients from the MIMIC II database. The challenge was organized as two events: event 1 measured performance of a binary classifier, and event 2 measured performance of a risk estimator. The score of event 1 was the lower of sensitivity and positive predictive value. The score for event 2 was a range-normalized Hosmer-Lemeshow statistic. A baseline algorithm (using SAPS-1) obtained event 1 and 2 scores of 0.3125 and 68.58 respectively. Most participants submitted entries that outperformed the baseline algorithm. The top final scores for events 1 and 2 were 0.5353 and 17.88 respectively.</p>","PeriodicalId":72683,"journal":{"name":"Computing in cardiology","volume":"39 ","pages":"245-248"},"PeriodicalIF":0.0,"publicationDate":"2012-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3965265/pdf/nihms432772.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32217202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"ICU Outcome Predictions using Physiologic Trends in the First Two Days.","authors":"Mehmet Kayaalp","doi":"","DOIUrl":"","url":null,"abstract":"<p><strong>Aims: </strong>This study aims to accurately predict patient mortality in the ICU. Given all physiologic measurements in the first 48 hours of the ICU stay, the Bayesian model of the study predicts outcome with a posterior probability.</p><p><strong>Methods: </strong>This study modeled the outcome as a binary random variable dependent on trends of daily physiologic measures of the patient, where trends were conditionally independent given the outcome. A two-day trend is a sequence of two discrete values, one for each day. Each value (low, medium, high or unmeasured) is a function of the arithmetic mean of that measure on the corresponding day.</p><p><strong>Results: </strong>The prediction performance of the model was measured as the minimum of sensitivity and positive predictive values. The model yielded a score of 0.39 along with a Hosmer-Lemeshow H statistic of 36, which measures calibration. The perfect scores would be 1.0 and 0, respectively.</p><p><strong>Conclusion: </strong>The prediction performance of the study was an improvement over the established ICU scoring metric SAPS-I, whose score was 0.32. Calibration of the model outputs was comparable to that of SAPS-I.</p>","PeriodicalId":72683,"journal":{"name":"Computing in cardiology","volume":" ","pages":"977-980"},"PeriodicalIF":0.0,"publicationDate":"2012-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3607431/pdf/nihms435794.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40231716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Action Potential Propagation Through Tissue Lacking Gap Junctions: Application to Engrafted Cells in Myocardial Infarcts.","authors":"Niels F Otani","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Engraftment of viable, electrically functional cells into a myocardial infarct as a method for restoring functionality is currently a topic of active research interest. Cells implanted in this way can form gap junction connectivity with each other, but often do not connect well with the surrounding tissue outside the infarct. Using a bidomain computer simulation model, we find that activation of these implanted cells by outside propagating action potentials is nevertheless possible, even if no gap junction connectivity to the surrounding tissue exists at all. The mechanism by which this action potential \"tunneling\" process occurs involves a current path that passes through both the intracellular and extracellular spaces, and is fundamentally spatially two-dimensional in nature. The typically convex boundary of the region occupied by these cells is found to greatly enhance the tunneling process, but unfortunately also hinders the ability of the activation of these cells to terminate reentrant waves propagating around the infarct.</p>","PeriodicalId":72683,"journal":{"name":"Computing in cardiology","volume":"38 ","pages":"25-28"},"PeriodicalIF":0.0,"publicationDate":"2011-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3466818/pdf/nihms352751.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"30974303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A Hypotensive Episode Predictor for Intensive Care based on Heart Rate and Blood Pressure Time Series.","authors":"J Lee, Rg Mark","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>In the intensive care unit (ICU), prompt therapeutic intervention to hypotensive episodes (HEs) is a critical task. Advance alerts that can prospectively identify patients at risk of developing an HE in the next few hours would be of considerable clinical value. In this study, we developed an automated, artificial neural network HE predictor based on heart rate and blood pressure time series from the MIMIC II database. The gap between prediction time and the onset of the 30-minute target window was varied from 1 to 4 hours. A 30-minute observation window preceding the prediction time provided input information to the predictor. While individual gap sizes were evaluated independently, weighted posterior probabilities based on different gap sizes were also investigated. The results showed that prediction performance degraded as gap size increased and the weighting scheme induced negligible performance improvement. Despite low positive predictive values, the best mean area under ROC curve was 0.934.</p>","PeriodicalId":72683,"journal":{"name":"Computing in cardiology","volume":"2010 26-29 Sept. 2010","pages":"81-84"},"PeriodicalIF":0.0,"publicationDate":"2011-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3162312/pdf/nihms299859.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"30105481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Point Process Heart Rate Variability Assessment during Sleep Deprivation.","authors":"L Citi, Eb Klerman, En Brown, R Barbieri","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>To investigate the potential relationships between Heart rate variability (HRV) and objective performance-subjective alertness measures during sleep deprivation, a novel point process algorithm was applied to ECG data from healthy young subjects in a 52-hour Constant Routine protocol, which includes sleep deprivation. Our algorithm is able to estimate the time-varying behavior of the HRV spectral indexes in an on-line instantaneous fashion. Results demonstrate the ability of our framework to provide high time-resolution sympatho-vagal dynamics as measured by spectral low frequency (LF) and high frequency (HF) power. Correlation analysis on individual subjects reveals a relevant correspondence between LF/HF and subjective alertness during the initial hours of sleep deprivation. At longer times awake, high correlation levels between LF/HF and objective performance indicate an increasing sympathetic drive as performance measures worsen. These results suggest that our point-process based HRV assessment could aid in real-time prediction of performance-alertness.</p>","PeriodicalId":72683,"journal":{"name":"Computing in cardiology","volume":"37 ","pages":"721-724"},"PeriodicalIF":0.0,"publicationDate":"2010-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3110699/pdf/nihms249624.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"30585635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jess D Tate, Jeroen G Stinstra, Thomas A Pilcher, Rob S Macleod
{"title":"Measurement of Defibrillator Surface Potentials for Simulation Verification.","authors":"Jess D Tate, Jeroen G Stinstra, Thomas A Pilcher, Rob S Macleod","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Despite the growing use of implantable cardioverter defibrillators (ICDs) in adults and children, there has been little progress in optimizing device and electrode placement. To facilitate effective placement of ICDs, especially in pediatric cases, we have developed a predictive model that evaluates the efficacy of a delivered shock. Most recently, we have also developed an experimental validation approach based on measurements from clinical cases. The approach involves obtaining body surface potential maps of ICD discharges during implantation surgery and comparing these measured potentials with simulated surface potentials to determine simulation accuracy. Comparison of the simulated and measured potentials yielded very similar patterns and a typical correlation greater than 0.9, suggesting that the predictive simulation generates realistic potential values. Ongoing sensitivity studies will determine the robustness of the results and pave the way for use of this approach for assisting optimization of ICD use.</p>","PeriodicalId":72683,"journal":{"name":"Computing in cardiology","volume":"37 ","pages":"853-856"},"PeriodicalIF":0.0,"publicationDate":"2010-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3138150/pdf/nihms302012.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"30024041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Torsadogenic Drug-induced Increased Short-term Variability of JT-area.","authors":"Xiao Jie, Blanca Rodriguez, Esther Pueyo","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Increased beat-to-beat variability of repolarization (BVR) has been suggested to indicate increased susceptibility to drug-induced arrhythmia. This study aimed to characterize BVR in patients before and after administration of sotalol, a torsadogenic antiarrhythmic drug, in the search for new biomarkers of proarrhythmic risk. ECG Recordings pre and post sotalol injection in two groups of patients (with and without history of drug-induced torsades de pointes) were obtained from THEW. ECG wave detection and delineation were performed via dyadic wavelet transform. BVR was evaluated by short-term variability (STV) of QTc interval and JT area. In both groups, sotalol resulted in significant increase in STV of JT area, while no significant change occurred in STV of QTc interval. Thus, STV of JT area, as a measure of BVR, has the potential to be a biomarker for drug toxicity.</p>","PeriodicalId":72683,"journal":{"name":"Computing in cardiology","volume":"2010 ","pages":"353-356"},"PeriodicalIF":0.0,"publicationDate":"2010-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3133449/pdf/nihms302688.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"29861644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Enhanced Computer Modeling of Cardiac Action Potential Dynamics using Experimental Data-Based Feedback.","authors":"Laura M Muñoz, Niels F Otani","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Mathematical models of cardiac action potential (AP) dynamics are useful for studying the formation of dynamically significant patterns such as alternans and conduction block. A closed-loop observer is an augmented version of a mathematical model, in which experimental data are supplied to the model through feedback. In this study, tools for observer analysis were applied to a two-variable Karma model of AP dynamics. For a single-cell system, it was confirmed that membrane potential data could be used to reconstruct the system state, and that Luenberger feedback could stabilize the observer. Next an observer with a 1D geometry was tested with microelectrode membrane-potential data from a 2.1cm in vitro canine Purkinje fiber. It was shown that the observer produced more accurate AP duration (APD) estimates than the model by itself. These reconstructed quantities could be used to provide enhanced information to anti-tachyarrhythmic stimulus protocols that depend on real-time measurements.</p>","PeriodicalId":72683,"journal":{"name":"Computing in cardiology","volume":" ","pages":"837-840"},"PeriodicalIF":0.0,"publicationDate":"2010-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3291476/pdf/nihms279190.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40141878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}