{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,30]],"date-time":"2025-11-30T09:19:57Z","timestamp":1764494397505,"version":"build-2065373602"},"reference-count":31,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2025,3,11]],"date-time":"2025-03-11T00:00:00Z","timestamp":1741651200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","award":["UIDB\/00306\/2020"],"award-info":[{"award-number":["UIDB\/00306\/2020"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JCM"],"abstract":"<jats:p>Introduction: Vasovagal syncope is a prevalent condition marked by transient loss of consciousness due to abrupt decreases in systemic blood pressure and\/or heart rate. Despite its clinical impact, the underlying haemodynamic mechanisms remain poorly defined, and data on age-related differences are limited and sometimes contradictory. Objectives: This study aimed to characterise haemodynamic adaptation patterns during a head-up tilt (HUT) test in adult (\u226518 years) and paediatric (&lt;18 years) patients with recurrent reflex syncope, compared with healthy adult controls. We sought to identify distinct temporal haemodynamic signatures and clarify potential age-related differences in syncope mechanisms. Methods: In this prospective observational study, participants underwent continuous beat-to-beat monitoring of cardiac output (CO), stroke volume (SV), heart rate (HR), and total peripheral resistance (TPR) during HUT. Linear mixed-effects models were used to examine time-by-group interactions, and post-hoc analyses were adjusted for multiple comparisons. Effect sizes and confidence intervals (CIs) were reported to quantify the magnitude of differences. Results: A total of 187 fainters (paediatric n = 81, adult n = 106) and 108 non-fainters (including 30 healthy controls) were studied. Compared to adult fainters, paediatric fainters showed a 24% larger decline in CO from baseline (mean difference of 1.1 L\/min [95% CI: 0.5\u20131.7], p = 0.003) and a 15\u201320 bpm higher peak HR (p = 0.001) during presyncope. Both subgroups experienced significant drops in TPR, which were more pronounced in paediatric fainters (effect size = 0.27, 95% CI: 0.12\u20130.42). Non-fainters (including controls) maintained relatively stable haemodynamics, with no significant decrease in CO or TPR (p &gt; 0.05). Age-related comparisons indicated a heavier reliance on HR modulation in paediatric fainters, leading to an earlier transition from compensated to pre-syncopal states. Conclusions: These findings demonstrate that paediatric fainters exhibit more abrupt decreases in CO and TPR than adults, alongside higher HR responses during orthostatic stress. Targeted interventions that address this heightened chronotropic dependency\u2014such as tilt-training protocols or strategies to improve venous return\u2014may be particularly beneficial in younger patients. An age-specific approach to diagnosis and management could improve risk stratification, minimise recurrent episodes, and enhance patient outcomes.<\/jats:p>","DOI":"10.3390\/jcm14061874","type":"journal-article","created":{"date-parts":[[2025,3,11]],"date-time":"2025-03-11T06:52:30Z","timestamp":1741675950000},"page":"1874","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Haemodynamic Patterns in Reflex Syncope: Insights from Head-Up Tilt Tests in Adults and Children"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2169-4024","authenticated-orcid":false,"given":"Sergio","family":"Laranjo","sequence":"first","affiliation":[{"name":"Pediatric Cardiology Department, Hospital de Santa Marta, 1150-293 Lisbon, Portugal"},{"name":"Cl\u00ednica Universit\u00e1ria de Cardiologia Pedi\u00e1trica, Centro Cl\u00ednico Acad\u00e9mico de Lisboa, 1150-293 Lisbon, Portugal"},{"name":"Comprehensive Health Research Center, NOVA Medical School, NMS, Faculdade de Ci\u00eancias M\u00e9dicas, FCM, Universidade NOVA de Lisboa, 1169-056 Lisbon, Portugal"}]},{"given":"Helena","family":"Fonseca","sequence":"additional","affiliation":[{"name":"Cardiology Department, Hospital de Santa Marta, 1150-199 Lisbon, Portugal"}]},{"given":"Ana Clara","family":"Felix","sequence":"additional","affiliation":[{"name":"Pediatric Cardiology Department, Hospital de Santa Marta, 1150-293 Lisbon, Portugal"},{"name":"Centro Cardiovascular da Universidade de Lisboa\u2014CCUL, 1649-004 Lisbon, Portugal"}]},{"given":"Alexandre V.","family":"Gourine","sequence":"additional","affiliation":[{"name":"Centre for Cardiovascular and Metabolic Neuroscience, University College London, London WC1E 6BT, UK"}]},{"given":"F\u00e1tima F.","family":"Pinto","sequence":"additional","affiliation":[{"name":"Pediatric Cardiology Department, Hospital de Santa Marta, 1150-293 Lisbon, Portugal"}]},{"given":"Mario","family":"Oliveira","sequence":"additional","affiliation":[{"name":"Cardiology Department, Hospital de Santa Marta, 1150-199 Lisbon, Portugal"},{"name":"Faculdade de Medicina da Universidade de Lisboa, 1649-004 Lisbon, Portugal"}]},{"given":"Isabel","family":"Rocha","sequence":"additional","affiliation":[{"name":"Centro Cardiovascular da Universidade de Lisboa\u2014CCUL, 1649-004 Lisbon, Portugal"},{"name":"Faculdade de Medicina da Universidade de Lisboa, 1649-004 Lisbon, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2025,3,11]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"e155","DOI":"10.1016\/j.hrthm.2017.03.004","article-title":"ACC\/AHA\/HRS guideline for the evaluation and management of patients with syncope: A report of the American College of Cardiology\/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society","volume":"14","author":"Shen","year":"2017","journal-title":"Heart Rhythm"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1883","DOI":"10.1093\/eurheartj\/ehy037","article-title":"ESC Scientific Document Group 2018 ESC guidelines for the diagnosis and management of syncope","volume":"39","author":"Brignole","year":"2018","journal-title":"Eur. 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