{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,3]],"date-time":"2026-10-03T11:41:43Z","timestamp":1791027703296,"version":"4.1.0"},"reference-count":33,"publisher":"Ovid Technologies (Wolters Kluwer Health)","issue":"17","content-domain":{"domain":["www.ahajournals.org"],"crossmark-restriction":true},"short-container-title":["Circulation"],"published-print":{"date-parts":[[1998,10,27]]},"abstract":"<jats:p>\n            <jats:italic>Background<\/jats:italic>\n            \u2014The wide range of clinical presentation of orthostatic vasovagal syncope suggests different underlying changes in the cardiac autonomic modulation.\n          <\/jats:p>\n          <jats:p>\n            <jats:italic>Methods and Results<\/jats:italic>\n            \u2014To evaluate the beat-by-beat modifications in the neural control of heart period preceding a syncopal event, we studied RR interval variability in 22 healthy subjects who experienced fainting for the first time during a 90\u00b0 head-up tilt and in 22 control subjects by means of time-variant power spectral analysis. Sympathetic and vagal modulations to the sinoatrial node were assessed by the normalized power of the low-frequency (LF, \u22480.1-Hz) and high-frequency (HF, \u22480.25-Hz) oscillatory components of RR variability. When the patients were supine, no differences were observed in the hemodynamic and spectral parameters of the 2 groups. During the tilt procedure, RR, LF\n            <jats:sub>NU<\/jats:sub>\n            , and HF\n            <jats:sub>NU<\/jats:sub>\n            (NU=normalized units) values were relatively stable in control subjects. During early tilt (T\n            <jats:sub>1<\/jats:sub>\n            ), subjects with syncope had reduced RR intervals compared with control subjects. In 13 subjects with syncope, RR decreased while LF\n            <jats:sub>NU<\/jats:sub>\n            and LF\/HF increased in the last minute of tilt before syncope (T\n            <jats:sub>2<\/jats:sub>\n            ). Conversely, in the remaining 9 fainters, LF\n            <jats:sub>NU<\/jats:sub>\n            and LF\/HF decreased from T\n            <jats:sub>1<\/jats:sub>\n            to T\n            <jats:sub>2<\/jats:sub>\n            and HF\n            <jats:sub>NU<\/jats:sub>\n            increased slightly.\n          <\/jats:p>\n          <jats:p>\n            <jats:italic>Conclusions<\/jats:italic>\n            \u2014Two different patterns may be recognized in the cardiac autonomic changes preceding an occasional vasovagal event, namely, one characterized by a progressive increase of the marker of cardiac sympathetic modulation up to the onset of syncope, the other by a sympathetic inhibition with an impending vagal predominance. The recognition of different pathophysiological mechanisms in fainters may have important therapeutic implications.\n          <\/jats:p>","DOI":"10.1161\/01.cir.98.17.1756","type":"journal-article","created":{"date-parts":[[2012,6,12]],"date-time":"2012-06-12T00:41:02Z","timestamp":1339461662000},"page":"1756-1761","update-policy":"https:\/\/doi.org\/10.1161\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":103,"title":["Cardiac Autonomic Patterns Preceding Occasional Vasovagal Reactions in Healthy Humans"],"prefix":"10.1161","volume":"98","author":[{"given":"Raffaello","family":"Furlan","sequence":"first","affiliation":[{"name":"From the Centro Ricerche Cardiovascolari, CNR; Medicina Interna II e Medicina Interna III (S.P.), Ospedale L. Sacco, Universita\u0300 di Milano; Divisione di Cardiologia (S.D.), Ospedale Uboldo, Cernusco S\/N; Medicina del Lavoro (F.B.), Ospedale di Novara; and Dipartimento di Bioingegneria (A.B., L.M., S.C.), Politecnico di Milano, Milano, Italy."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Simona","family":"Piazza","sequence":"additional","affiliation":[{"name":"From the Centro Ricerche Cardiovascolari, CNR; Medicina Interna II e Medicina Interna III (S.P.), Ospedale L. Sacco, Universita\u0300 di Milano; Divisione di Cardiologia (S.D.), Ospedale Uboldo, Cernusco S\/N; Medicina del Lavoro (F.B.), Ospedale di Novara; and Dipartimento di Bioingegneria (A.B., L.M., S.C.), Politecnico di Milano, Milano, Italy."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Simonetta","family":"Dell\u2019Orto","sequence":"additional","affiliation":[{"name":"From the Centro Ricerche Cardiovascolari, CNR; Medicina Interna II e Medicina Interna III (S.P.), Ospedale L. Sacco, Universita\u0300 di Milano; Divisione di Cardiologia (S.D.), Ospedale Uboldo, Cernusco S\/N; Medicina del Lavoro (F.B.), Ospedale di Novara; and Dipartimento di Bioingegneria (A.B., L.M., S.C.), Politecnico di Milano, Milano, Italy."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Franca","family":"Barbic","sequence":"additional","affiliation":[{"name":"From the Centro Ricerche Cardiovascolari, CNR; Medicina Interna II e Medicina Interna III (S.P.), Ospedale L. Sacco, Universita\u0300 di Milano; Divisione di Cardiologia (S.D.), Ospedale Uboldo, Cernusco S\/N; Medicina del Lavoro (F.B.), Ospedale di Novara; and Dipartimento di Bioingegneria (A.B., L.M., S.C.), Politecnico di Milano, Milano, Italy."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anna","family":"Bianchi","sequence":"additional","affiliation":[{"name":"From the Centro Ricerche Cardiovascolari, CNR; Medicina Interna II e Medicina Interna III (S.P.), Ospedale L. Sacco, Universita\u0300 di Milano; Divisione di Cardiologia (S.D.), Ospedale Uboldo, Cernusco S\/N; Medicina del Lavoro (F.B.), Ospedale di Novara; and Dipartimento di Bioingegneria (A.B., L.M., S.C.), Politecnico di Milano, Milano, Italy."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Luca","family":"Mainardi","sequence":"additional","affiliation":[{"name":"From the Centro Ricerche Cardiovascolari, CNR; Medicina Interna II e Medicina Interna III (S.P.), Ospedale L. Sacco, Universita\u0300 di Milano; Divisione di Cardiologia (S.D.), Ospedale Uboldo, Cernusco S\/N; Medicina del Lavoro (F.B.), Ospedale di Novara; and Dipartimento di Bioingegneria (A.B., L.M., S.C.), Politecnico di Milano, Milano, Italy."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sergio","family":"Cerutti","sequence":"additional","affiliation":[{"name":"From the Centro Ricerche Cardiovascolari, CNR; Medicina Interna II e Medicina Interna III (S.P.), Ospedale L. Sacco, Universita\u0300 di Milano; Divisione di Cardiologia (S.D.), Ospedale Uboldo, Cernusco S\/N; Medicina del Lavoro (F.B.), Ospedale di Novara; and Dipartimento di Bioingegneria (A.B., L.M., S.C.), Politecnico di Milano, Milano, Italy."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Massimo","family":"Pagani","sequence":"additional","affiliation":[{"name":"From the Centro Ricerche Cardiovascolari, CNR; Medicina Interna II e Medicina Interna III (S.P.), Ospedale L. Sacco, Universita\u0300 di Milano; Divisione di Cardiologia (S.D.), Ospedale Uboldo, Cernusco S\/N; Medicina del Lavoro (F.B.), Ospedale di Novara; and Dipartimento di Bioingegneria (A.B., L.M., S.C.), Politecnico di Milano, Milano, Italy."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alberto","family":"Malliani","sequence":"additional","affiliation":[{"name":"From the Centro Ricerche Cardiovascolari, CNR; Medicina Interna II e Medicina Interna III (S.P.), Ospedale L. Sacco, Universita\u0300 di Milano; Divisione di Cardiologia (S.D.), Ospedale Uboldo, Cernusco S\/N; Medicina del Lavoro (F.B.), Ospedale di Novara; and Dipartimento di Bioingegneria (A.B., L.M., S.C.), Politecnico di Milano, Milano, Italy."}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"276","reference":[{"key":"e_1_3_2_1_2","doi-asserted-by":"publisher","DOI":"10.1042\/cs0810575"},{"key":"e_1_3_2_2_2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1748-1716.1972.tb05247.x"},{"key":"e_1_3_2_3_2","first-page":"R742","volume":"251","year":"1986","unstructured":"Sander-Jensen K, Secher NH, Astrup A, Christensen NJ, Giese J, Schwartz TW, Warberg J, Bie P. Hypotension induced by passive head-up tilt: endocrine and circulatory mechanisms. 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