{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T04:06:58Z","timestamp":1760242018472,"version":"build-2065373602"},"reference-count":57,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2018,12,16]],"date-time":"2018-12-16T00:00:00Z","timestamp":1544918400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>The paper presents possible applications of entropy measures in analysis of biosignals recorded during head up tilt testing (HUTT) in patients with suspected vasovagal syndrome. The study group comprised 80 patients who developed syncope during HUTT (57 in the passive phase of the test (HUTT(+) group) and 23 who had negative result of passive phase and developed syncope after provocation with nitroglycerine (HUTT(\u2212) group)). The paper focuses on assessment of monitored signals\u2019 complexity (heart rate expressed as R-R intervals (RRI), blood pressure (sBP, dBP) and stroke volume (SV)) using various types of entropy measures (Sample Entropy (SE), Fuzzy Entropy (FE), Shannon Entropy (Sh), Conditional Entropy (CE), Permutation Entropy (PE)). Assessment of the complexity of signals in supine position indicated presence of significant differences between HUTT(+) versus HUTT(\u2212) patients only for Conditional Entropy (CE(RRI)). Values of CE(RRI) higher than 0.7 indicate likelihood of a positive result of HUTT already at the passive phase. During tilting, in the pre-syncope phase, significant differences were found for: (SE(sBP), SE(dBP), FE(RRI), FE(sBP), FE(dBP), FE(SV), Sh(sBP), Sh(SV), CE(sBP), CE(dBP)). HUTT(+) patients demonstrated significant changes in signals\u2019 complexity more frequently than HUTT(\u2212) patients. When comparing entropy measurements done in the supine position with those during tilting, SV assessed in HUTT(+) patients was the only parameter for which all tested measures of entropy (SE(SV), FE(SV), Sh(SV), CE(SV), PE(SV)) showed significant differences.<\/jats:p>","DOI":"10.3390\/e20120976","type":"journal-article","created":{"date-parts":[[2018,12,18]],"date-time":"2018-12-18T02:15:59Z","timestamp":1545099359000},"page":"976","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Entropy Measures in Analysis of Head up Tilt Test Outcome for Diagnosing Vasovagal Syncope"],"prefix":"10.3390","volume":"20","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0388-3446","authenticated-orcid":false,"given":"Katarzyna","family":"Buszko","sequence":"first","affiliation":[{"name":"Department of Theoretical Foundations of Bio-Medical Science and Medical Informatics, Collegium Medicum, Nicolaus Copernicus University, 85-067 Bydgoszcz, Poland"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8234-2773","authenticated-orcid":false,"given":"Agnieszka","family":"Pi\u0105tkowska","sequence":"additional","affiliation":[{"name":"Department of Emergency Medicine, Wroclaw Medical University, 02-091 Wroclaw, Poland"},{"name":"1st Department of Cardiology, Medical University of Warsaw, 02-091 Warsaw, Poland"}]},{"given":"Edward","family":"Ko\u017aluk","sequence":"additional","affiliation":[{"name":"1st Department of Cardiology, Medical University of Warsaw, 02-091 Warsaw, Poland"}]},{"given":"Tomasz","family":"Fabiszak","sequence":"additional","affiliation":[{"name":"Department of Cardiology and Internal Diseases, Collegium Medicum, Nicolaus Copernicus University, 85-067 Bydgoszcz, Poland"}]},{"given":"Grzegorz","family":"Opolski","sequence":"additional","affiliation":[{"name":"1st Department of Cardiology, Medical University of Warsaw, 02-091 Warsaw, Poland"}]}],"member":"1968","published-online":{"date-parts":[[2018,12,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"153","DOI":"10.5506\/APhysPolBSupp.5.153","article-title":"Entropy measures of heart rate variability for short ECG datasets in patients with congestive heart failure","volume":"5","author":"Graff","year":"2012","journal-title":"Acta Phys. 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