{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,30]],"date-time":"2026-09-30T04:16:30Z","timestamp":1790741790260,"version":"4.1.0"},"reference-count":33,"publisher":"Ovid Technologies (Wolters Kluwer Health)","issue":"1","content-domain":{"domain":["www.ahajournals.org"],"crossmark-restriction":true},"short-container-title":["Stroke"],"published-print":{"date-parts":[[1998,1]]},"abstract":"<jats:p>\n            <jats:italic>Background and Purpose<\/jats:italic>\n            \u2014We sought to evaluate cerebral autoregulation in patients with orthostatic hypotension (OH).\n          <\/jats:p>\n          <jats:p>\n            <jats:italic>Methods<\/jats:italic>\n            \u2014We studied 21 patients (aged 52 to 78 years) with neurogenic OH during 80\u00b0 head-up tilt. Blood flow velocities (BFV) from the middle cerebral artery were continuously monitored with transcranial Doppler sonography, as were heart rate, blood pressure (BP), cardiac output, stroke volume, CO\n            <jats:sub>2<\/jats:sub>\n            , total peripheral resistance, and cerebrovascular resistance.\n          <\/jats:p>\n          <jats:p>\n            <jats:italic>Results<\/jats:italic>\n            \u2014All OH patients had lower BP (\n            <jats:italic>P<\/jats:italic>\n            &lt;.0001), BFV_diastolic (\n            <jats:italic>P<\/jats:italic>\n            &lt;.05), CVR (\n            <jats:italic>P<\/jats:italic>\n            &lt;.007), and TPR (\n            <jats:italic>P<\/jats:italic>\n            &lt;.02) during head-up tilt than control subjects. In control subjects, no correlations between BFV and BP were found during head-up tilt, suggesting normal autoregulation. OH patients could be separated into those with normal or expanded autoregulation (OH_NA; n=16) and those with autoregulatory failure (OH_AF; n=5). The OH_NA group showed either no correlation between BFV and BP (n=8) or had a positive BFV\/BP correlation (\n            <jats:italic>R<\/jats:italic>\n            <jats:sup>2<\/jats:sup>\n            &gt;.75) but with a flat slope. An expansion of the \u201cautoregulated\u201d range was seen in some patients. The OH_AF group was characterized by a profound fall in BFV in response to a small reduction in BP (mean \u0394BP &lt;40 mm Hg;\n            <jats:italic>R<\/jats:italic>\n            <jats:sup>2<\/jats:sup>\n            &gt;.75).\n          <\/jats:p>\n          <jats:p>\n            <jats:italic>Conclusions<\/jats:italic>\n            \u2014The most common patterns of cerebral response to OH are autoregulatory failure with a flat flow-pressure relationship or intact autoregulation with an expanded autoregulated range. The least common pattern is autoregulatory failure with a steep flow-pressure relationship. Patients with patterns 1 and 2 have an enhanced capacity to cope with OH, while those with pattern 3 have reduced capacity.\n          <\/jats:p>","DOI":"10.1161\/01.str.29.1.104","type":"journal-article","created":{"date-parts":[[2011,6,17]],"date-time":"2011-06-17T20:08:03Z","timestamp":1308341283000},"page":"104-111","update-policy":"https:\/\/doi.org\/10.1161\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":205,"title":["Autoregulation of Cerebral Blood Flow in Orthostatic Hypotension"],"prefix":"10.1161","volume":"29","author":[{"given":"Vera","family":"Novak","sequence":"first","affiliation":[{"name":"From the Autonomic Disorders Center, Department of Neurology, Mayo Clinic and Foundation, Rochester, Minn."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Peter","family":"Novak","sequence":"additional","affiliation":[{"name":"From the Autonomic Disorders Center, Department of Neurology, Mayo Clinic and Foundation, Rochester, Minn."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Judith M.","family":"Spies","sequence":"additional","affiliation":[{"name":"From the Autonomic Disorders Center, Department of Neurology, Mayo Clinic and Foundation, Rochester, Minn."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Phillip A.","family":"Low","sequence":"additional","affiliation":[{"name":"From the Autonomic Disorders Center, Department of Neurology, Mayo Clinic and Foundation, Rochester, Minn."}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"276","reference":[{"key":"e_1_3_2_1_2","unstructured":"Suarez GA Low PA. 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