{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,26]],"date-time":"2026-10-26T22:46:14Z","timestamp":1793054774115,"version":"4.5.0"},"reference-count":49,"publisher":"IOP Publishing","issue":"5","license":[{"start":{"date-parts":[[2024,5,15]],"date-time":"2024-05-15T00:00:00Z","timestamp":1715731200000},"content-version":"vor","delay-in-days":14,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2024,5,15]],"date-time":"2024-05-15T00:00:00Z","timestamp":1715731200000},"content-version":"tdm","delay-in-days":14,"URL":"https:\/\/iopscience.iop.org\/info\/page\/text-and-data-mining"}],"funder":[{"DOI":"10.13039\/100000968","name":"American Heart Association","doi-asserted-by":"crossref","award":["23IPA1054351"],"award-info":[{"award-number":["23IPA1054351"]}],"id":[{"id":"10.13039\/100000968","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":["iopscience.iop.org"],"crossmark-restriction":false},"short-container-title":["Physiol. Meas."],"published-print":{"date-parts":[[2024,5,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>\n                    <jats:italic>Objective.<\/jats:italic>\n                    The EPHNOGRAM project aimed to develop a low-cost, low-power device for simultaneous electrocardiogram (ECG) and phonocardiogram (PCG) recording, with additional channels for environmental audio to enhance PCG through active noise cancellation. The objective was to study multimodal electro-mechanical activities of the heart, offering insights into the differences and synergies between these modalities during various cardiac activity levels.\n                    <jats:italic>Approach.<\/jats:italic>\n                    We developed and tested several hardware prototypes of a simultaneous ECG-PCG acquisition device. Using this technology, we collected simultaneous ECG and PCG data from 24 healthy adults during different physical activities, including resting, walking, running, and stationary biking, in an indoor fitness center. The data were annotated using a robust software that we developed for detecting ECG R-peaks and PCG S1 and S2 components, and overseen by a human expert. We also developed machine learning models using ECG-based, PCG-based, and joint ECG-PCG features, like R\u2013R and S1\u2013S2 intervals, to classify physical activities and analyze electro-mechanical dynamics.\n                    <jats:italic>Main results.<\/jats:italic>\n                    The results show a significant coupling between ECG and PCG components, especially during high-intensity exercise. Notable micro-variations in S2-based heart rate show differences in the heart\u2019s electrical and mechanical functions. The Lomb-Scargle periodogram and approximate entropy analyses confirm the higher volatility of S2-based heart rate compared to ECG-based heart rate. Correlation analysis shows stronger coupling between R\u2013R and R-S1 intervals during high-intensity activities. Hybrid ECG-PCG features, like the R-S2 interval, were identified as more informative for physical activity classification through mRMR feature selection and SHAP value analysis.\n                    <jats:italic>Significance.<\/jats:italic>\n                    The EPHNOGRAM database, is available on PhysioNet. The database enhances our understanding of cardiac function, enabling future studies on the heart\u2019s mechanical and electrical interrelationships. The results of this study can contribute to improved cardiac condition diagnoses. Additionally, the designed hardware has the potential for integration into wearable devices and the development of multimodal stress test technologies.\n                  <\/jats:p>","DOI":"10.1088\/1361-6579\/ad43af","type":"journal-article","created":{"date-parts":[[2024,4,25]],"date-time":"2024-04-25T18:43:01Z","timestamp":1714070581000},"page":"055005","update-policy":"https:\/\/doi.org\/10.1088\/crossmark-policy","source":"Crossref","is-referenced-by-count":17,"title":["An open-access simultaneous electrocardiogram and phonocardiogram database"],"prefix":"10.1088","volume":"45","author":[{"given":"Arsalan","family":"Kazemnejad","sequence":"first","affiliation":[{"name":"Independent Researcher"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sajjad","family":"Karimi","sequence":"additional","affiliation":[{"name":"Emory University"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Peiman","family":"Gordany","sequence":"additional","affiliation":[{"name":"Independent Researcher"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gari D","family":"Clifford","sequence":"additional","affiliation":[{"name":"Emory University"},{"name":"Georgia Institute of Technology"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4913-6825","authenticated-orcid":true,"given":"Reza","family":"Sameni","sequence":"additional","affiliation":[{"name":"Emory University"},{"name":"Georgia Institute of Technology"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"266","published-online":{"date-parts":[[2024,5,15]]},"reference":[{"key":"pmeaad43afbib2","first-page":"323","type":"journal-article","article-title":"Exercise testing of patients with coronary artery disease","volume":"3","author":"Bruce","year":"1971","journal-title":"Ann. 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