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Good WW, Erem B, Zenger B, Coll-Font J, Bergquist JA, Brooks DH, MacLeod RS. Characterizing the transient electrocardiographic signature of ischemic stress using Laplacian Eigenmaps for dimensionality reduction. Comput Biol Med 2020; 127:104059. [PMID: 33171289 DOI: 10.1016/j.compbiomed.2020.104059] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Revised: 10/06/2020] [Accepted: 10/11/2020] [Indexed: 11/17/2022]
Abstract
OBJECTIVE Despite a long history of ECG-based monitoring of acute ischemia quantified by several widely used clinical markers, the diagnostic performance of these metrics is not yet satisfactory, motivating a data-driven approach to leverage underutilized information in the electrograms. This study introduces a novel metric for acute ischemia, created using a machine learning technique known as Laplacian eigenmaps (LE), and compares the diagnostic and temporal performance of the LE metric against traditional metrics. METHODS The LE technique uses dimensionality reduction of simultaneously recorded time signals to map them into an abstract space in a manner that highlights the underlying signal behavior. To evaluate the performance of an electrogram-based LE metric compared to current standard approaches, we induced episodes of transient, acute ischemia in large animals and captured the electrocardiographic response using up to 600 electrodes within the intramural and epicardial domains. RESULTS The LE metric generally detected ischemia earlier than all other approaches and with greater accuracy. Unlike other metrics derived from specific features of parts of the signals, the LE approach uses the entire signal and provides a data-driven strategy to identify features that reflect ischemia. CONCLUSION The superior performance of the LE metric suggests there are underutilized features of electrograms that can be leveraged to detect the presence of acute myocardial ischemia earlier and more robustly than current methods. SIGNIFICANCE The earlier detection capabilities of the LE metric on the epicardial surface provide compelling motivation to apply the same approach to ECGs recorded from the body surface.
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Affiliation(s)
- W W Good
- Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, UT, USA; Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, USA; Nora Eccles Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA.
| | - B Erem
- TrueMotion, Boston, MA, USA
| | - B Zenger
- Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, UT, USA; Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, USA; Nora Eccles Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA; School of Medicine, University of Utah, Salt Lake City, UT, USA
| | - J Coll-Font
- Cardiovascular Research Center (CVRC), Massachusetts General Hospital, Boston, MA, USA
| | - J A Bergquist
- Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, UT, USA; Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, USA; Nora Eccles Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
| | - D H Brooks
- SPIRAL Group, ECE Dept., Northeastern University, Boston, MA, USA
| | - R S MacLeod
- Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, UT, USA; Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, USA; Nora Eccles Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
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Good WW, Erem B, Zenger B, Coll-Font J, Brooks DH, MacLeod RS. Temporal Performance of Laplacian Eigenmaps and 3D Conduction Velocity in Detecting Ischemic Stress. J Electrocardiol 2018; 51:S116-S120. [PMID: 30122455 PMCID: PMC6263792 DOI: 10.1016/j.jelectrocard.2018.08.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 08/07/2018] [Accepted: 08/12/2018] [Indexed: 10/28/2022]
Abstract
BACKGROUND Myocardial ischemia has a complex and time-varying electrocardiographic signature that is used to diagnose and stratify severity. Despite the ubiquitous clinical use of the ECG to detect ischemia, the sensitivity and specificity of ECG based detection of myocardial ischemia are still inadequate. PURPOSE The purpose of this study was to compare, using animal models, the performance of several traditional ECG-based metrics for detecting acute ischemia against two novel metrics, the Laplacian Eigenmap (LE) parameters and a three-dimensional estimate of Conduction Velocity (CV). METHODS LE is a machine learning technique that reduces the dimensions of simultaneously recorded time signals using a non-linear embedding followed by an singular value decomposition to represent each multichannel recording as a single trajectory on a manifold. Perturbations in the trajectories suggest the presence of myocardial ischemia. CV was computed using a tetrahedral mesh created from the electrode locations of transmural plunge needles. To validate the results, we used electrograms collected over 95 episodes of acutely induced myocardial ischemia in 15 canine and 2 porcine subjects. The LE and CV metrics were compared against traditional metrics derived from the ST segment, the T wave, the QRS of the same electrograms. The response time and robustness of each metric was quantified using parameters we defined as time to threshold (TTT) and contrast ratio (CR). RESULTS The temporal performance of the metrics evaluated throughout the ischemic episodes showed a consistent relationship; the LE metrics changed earlier than those from the T wave, which were followed by those from the ST segment, and finally from the QRS. The CV results showed median drops in conduction velocity throughout the perfusion bed of more than 23% in canines and over 12% during half of the induced ischemia episodes in swine. The other half of the episodes in swine produced a 76% drop. CONCLUSIONS Our results suggest that the LE metric is more sensitive to acute ischemia than traditional single parameters used in previous studies, likely because it incorporates the entire QRST across multiple electrodes in a way that captures their most salient features in a low-dimensional space. The estimates of conduction velocity suggest substantial, in some cases dramatic slowing of the spread of activation, a finding that is not surprising but has not been documented in such three-dimensional detail before. The experiments and these new metrics provide a means to both explore details of the acute ischemic response not available from humans and suggest a path to translate this knowledge into improvements in clinical scoring of ischemia.
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Affiliation(s)
- Wilson W Good
- Scientific Computing and Imaging Institute, Biomedical Engineering, University of Utah, Salt Lake City, UT, USA.
| | - Burak Erem
- TrueMotion, Boston, MA, USA; Computational Radiology Lab., Boston Children's Hospital, Boston, MA, USA
| | - Brian Zenger
- Scientific Computing and Imaging Institute, Biomedical Engineering, University of Utah, Salt Lake City, UT, USA
| | - Jaume Coll-Font
- Computational Radiology Lab., Boston Children's Hospital, Boston, MA, USA
| | - Dana H Brooks
- SPIRAL Group, ECE Dept., Northeastern University, Boston, MA, USA
| | - Rob S MacLeod
- Scientific Computing and Imaging Institute, Biomedical Engineering, University of Utah, Salt Lake City, UT, USA
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Swenne CA, Pahlm O, Atwater BD, Bacharova L. Galen Wagner, M.D., Ph.D. (1939–2016) as international mentor of young investigators in electrocardiology. J Electrocardiol 2017; 50:21-46. [DOI: 10.1016/j.jelectrocard.2016.11.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Dr. Galen Wagner (1939-2016) as an Academic Writer: An Overview of his Peer-reviewed Scientific Publications. J Electrocardiol 2017; 50:47-73. [DOI: 10.1016/j.jelectrocard.2016.11.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Scientific STAFF and MALT meetings — past, present, and future. J Electrocardiol 2016; 49:259-62. [DOI: 10.1016/j.jelectrocard.2016.02.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Indexed: 11/18/2022]
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Drew BJ, Sommargren CE, Tolan GD, Macfarlane PW, Wagner GS, Strauss DG, Burke MC, Kligfield PD, Rowlandson I, Lux RL. In memoriam: A tribute to the work and lives of Ron Selvester and Rory Childers. J Electrocardiol 2015; 48:1088-98. [PMID: 26422547 DOI: 10.1016/j.jelectrocard.2015.08.037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Indexed: 11/25/2022]
Abstract
At the April, 2015 International Society for Computerized Electrocardiology (ISCE) Annual Conference in San Jose, CA, a special session entitled Remembering Ron & Rory was held to pay tribute to the extraordinary work and lives of two experts in electrocardiology. The session was well attended by conference attendees, Childers' family members and friends, and additional colleagues who traveled to San Jose solely to participate in this session. The purpose of the present paper is to document the spirit of this special session as faithfully as possible using the words of the session speakers.
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Affiliation(s)
- Barbara J Drew
- Department of Physiological Nursing, University of California, San Francisco, CA, USA
| | - Claire E Sommargren
- Department of Physiological Nursing, University of California, San Francisco, CA, USA.
| | - Gil D Tolan
- Health Science Center, University of Texas, San Antonio, TX, USA
| | - Peter W Macfarlane
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, UK
| | - Galen S Wagner
- Duke Clinical Research Institute, Duke University, Durham, NC, USA
| | - David G Strauss
- Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, United States Food and Drug Administration, Silver Spring, MD, USA
| | - Martin C Burke
- Heart Rhythm Center, University of Chicago, Chicago, IL, USA
| | | | | | - Robert L Lux
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
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Romero D, Ringborn M, Laguna P, Pahlm O, Pueyo E. Depolarization Changes During Acute Myocardial Ischemia by Evaluation of QRS Slopes: Standard Lead and Vectorial Approach. IEEE Trans Biomed Eng 2011; 58:110-20. [DOI: 10.1109/tbme.2010.2076385] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Pueyo E, Sornmo L, Laguna P. QRS Slopes for Detection and Characterization of Myocardial Ischemia. IEEE Trans Biomed Eng 2008; 55:468-77. [DOI: 10.1109/tbme.2007.902228] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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