{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,19]],"date-time":"2026-08-19T17:33:25Z","timestamp":1787160805401,"version":"build-2736575974"},"reference-count":24,"publisher":"Ovid Technologies (Wolters Kluwer Health)","issue":"16","content-domain":{"domain":["www.ahajournals.org"],"crossmark-restriction":true},"short-container-title":["JAHA"],"published-print":{"date-parts":[[2026,8,18]]},"abstract":"\n Background<\/jats:title>\n Orthostatic intolerance is common in hypermobile Ehlers\u2013Danlos syndrome (hEDS) with one third of patients fulfilling postural orthostatic tachycardia syndrome criteria. Our aim was to assess cerebral blood flow in patients with hEDS and postural orthostatic tachycardia syndrome during orthostasis, which may be responsible for orthostatic intolerance.<\/jats:p>\n <\/jats:sec>\n \n Methods<\/jats:title>\n In 18 individuals with hEDS and postural orthostatic tachycardia syndrome and 20 healthy controls, we conducted real\u2010time phase contrast magnetic resonance imaging of the middle cerebral artery with and without an orthostatic challenge through 30\u2009mm\u2009Hg lower\u2010body negative pressure.<\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n \n During lower\u2010body negative pressure, heart rate increased more in hEDS than in controls (15.0\u00b18.3\u2009bpm versus 7.8\u00b17.7\u2009bpm,\n P<\/jats:italic>\n =0.009); blood pressure remained unchanged; middle cerebral artery flow per heartbeat decreased more in hEDS (\u221228%\u00b116% versus \u221215%\u00b113% in controls,\n P<\/jats:italic>\n =0.013) with decreased mean volumetric flow in hEDS (\u221212%\u00b117%,\n P<\/jats:italic>\n <0.001 versus \u22126%\u00b18% in controls,\n P<\/jats:italic>\n =0.102); average middle cerebral artery peak blood flow velocity decreased in both groups (hEDS: 44.6\u00b18.1\u2009cm\/s to 37.6\u00b18.4\u2009cm\/s,\n P<\/jats:italic>\n <0.001; controls: 40.3\u00b110.9\u2009cm\/s to 36.9\u00b111.1\u2009cm\/s,\n P<\/jats:italic>\n =0.018); respiration rate increased in hEDS (14.3\u00b15.1\/min to 17.4\u00b15.3\/min,\n P<\/jats:italic>\n =0.002) leading to a decrease in end\u2010tidal CO\n 2<\/jats:sub>\n (39.2\u00b14.2\u2009mm\u2009Hg to 35.6\u00b16.4\u2009mm\u2009Hg,\n P<\/jats:italic>\n =0.025), and cerebrovascular resistance increased more in hEDS (50.8%\u00b148.4%,\n P<\/jats:italic>\n <0.001) versus (20.3%\u00b120.6%,\n P<\/jats:italic>\n =0.005) in controls.\n <\/jats:p>\n <\/jats:sec>\n \n Conclusions<\/jats:title>\n Individuals with hEDS and postural orthostatic tachycardia syndrome maintain cerebral perfusion primarily through tachycardic compensation during orthostatic stress despite hypocapnic vasoconstriction.<\/jats:p>\n <\/jats:sec>\n \n Registration<\/jats:title>\n \n URL:\n https:\/\/drks.de\/search\/en<\/jats:ext-link>\n ; Unique Identifier: DRKS00028279.\n <\/jats:p>\n <\/jats:sec>","DOI":"10.1161\/jaha.126.050302","type":"journal-article","created":{"date-parts":[[2026,8,8]],"date-time":"2026-08-08T03:41:55Z","timestamp":1786160515000},"update-policy":"https:\/\/doi.org\/10.1161\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":0,"title":["Excessive Hypocapnic Cerebral Vasoconstriction in Hypermobile Ehlers\u2013Danlos Syndrome Assessed With Real\u2010Time Magnetic Resonance Imaging During Lower\u2010Body Negative Pressure"],"prefix":"10.1161","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7044-6065","authenticated-orcid":false,"given":"Darius A.","family":"Gerlach","sequence":"first","affiliation":[{"name":"German Aerospace Center (DLR)","place":["Cologne, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anja","family":"Bach","sequence":"additional","affiliation":[{"name":"German Aerospace Center (DLR)","place":["Cologne, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Laura","family":"de Boni","sequence":"additional","affiliation":[{"name":"German Aerospace Center (DLR)","place":["Cologne, Germany"]},{"name":"University of Bonn","place":["Bonn, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fiona","family":"Fischer","sequence":"additional","affiliation":[{"name":"University Clinic RWTH Aachen","place":["Aachen, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tatjana","family":"Barth","sequence":"additional","affiliation":[{"name":"University Clinic RWTH Aachen","place":["Aachen, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7574-6649","authenticated-orcid":false,"given":"Alex","family":"Hoff","sequence":"additional","affiliation":[{"name":"German Aerospace Center (DLR)","place":["Cologne, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jorge","family":"Manuel","sequence":"additional","affiliation":[{"name":"German Aerospace Center (DLR)","place":["Cologne, Germany"]},{"name":"University of Bonn","place":["Bonn, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4518-0706","authenticated-orcid":false,"given":"Jens","family":"Jordan","sequence":"additional","affiliation":[{"name":"German Aerospace Center (DLR)","place":["Cologne, Germany"]},{"name":"University of Cologne","place":["Cologne, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3427-4806","authenticated-orcid":false,"given":"Andrea","family":"Maier","sequence":"additional","affiliation":[{"name":"University Clinic RWTH Aachen","place":["Aachen, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5672-1187","authenticated-orcid":false,"given":"Jens","family":"Tank","sequence":"additional","affiliation":[{"name":"German Aerospace Center (DLR)","place":["Cologne, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"276","reference":[{"key":"e_1_3_2_2_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.rare.2025.100107"},{"key":"e_1_3_2_3_2","doi-asserted-by":"publisher","DOI":"10.1002\/ajmg.a.62197"},{"key":"e_1_3_2_4_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.ajmo.2025.100111"},{"key":"e_1_3_2_5_2","doi-asserted-by":"publisher","DOI":"10.1056\/nejm200010053431404"},{"key":"e_1_3_2_6_2","doi-asserted-by":"publisher","DOI":"10.1016\/s0002-9343(98)00364-7"},{"key":"e_1_3_2_7_2","doi-asserted-by":"publisher","DOI":"10.1161\/01.str.29.9.1876"},{"key":"e_1_3_2_8_2","doi-asserted-by":"publisher","DOI":"10.1161\/hc6172.099397"},{"key":"e_1_3_2_9_2","doi-asserted-by":"publisher","DOI":"10.1152\/ajpheart.00138.2009"},{"key":"e_1_3_2_10_2","doi-asserted-by":"publisher","DOI":"10.1161\/JAHA.120.017861"},{"key":"e_1_3_2_11_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41598-025-87748-4"},{"key":"e_1_3_2_12_2","doi-asserted-by":"publisher","DOI":"10.1152\/japplphysiol.00285.2014"},{"key":"e_1_3_2_13_2","doi-asserted-by":"publisher","DOI":"10.1152\/japplphysiol.00016.2023"},{"key":"e_1_3_2_14_2","doi-asserted-by":"publisher","DOI":"10.1016\/s0167-8760(01)00184-2"},{"key":"e_1_3_2_15_2","doi-asserted-by":"publisher","DOI":"10.1007\/s00296-021-04832-4"},{"key":"e_1_3_2_16_2","doi-asserted-by":"publisher","DOI":"10.1136\/practneurol-2016-001405"},{"key":"e_1_3_2_17_2","doi-asserted-by":"publisher","DOI":"10.1002\/nbm.1812"},{"key":"e_1_3_2_18_2","doi-asserted-by":"publisher","DOI":"10.1161\/JAHA.122.026437"},{"key":"e_1_3_2_19_2","doi-asserted-by":"publisher","DOI":"10.1161\/01.cir.98.20.2154"},{"key":"e_1_3_2_20_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.ejim.2025.106529"},{"key":"e_1_3_2_21_2","doi-asserted-by":"publisher","DOI":"10.1152\/physiol.2024.39.S1.614"},{"key":"e_1_3_2_22_2","doi-asserted-by":"publisher","DOI":"10.1093\/eurheartj\/ehae653"},{"key":"e_1_3_2_23_2","doi-asserted-by":"publisher","DOI":"10.1111\/joim.13566"},{"key":"e_1_3_2_24_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.mayocp.2012.10.013"},{"key":"e_1_3_2_25_2","doi-asserted-by":"publisher","DOI":"10.1093\/brain\/awn093"}],"container-title":["Journal 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