{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T01:53:17Z","timestamp":1787017997841,"version":"build-2736575974"},"reference-count":0,"publisher":"Ovid Technologies (Wolters Kluwer Health)","issue":"2","content-domain":{"domain":["www.ahajournals.org"],"crossmark-restriction":true},"short-container-title":["Circulation"],"published-print":{"date-parts":[[1994,8]]},"abstract":"<jats:sec>\n                    <jats:title>BACKGROUND<\/jats:title>\n                    <jats:p>\"Inappropriate\" sinus tachycardia (IST) is an uncommon and poorly defined atrial tachycardia characterized by inappropriate tachycardia and exaggerated acceleration of heart rate with \"normal\" P wave. The mechanism of this tachycardia is unknown. The purpose of the present study was to determine the role of autonomic balance in the genesis of IST.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>METHODS AND RESULTS<\/jats:title>\n                    <jats:p>Six female patients aged 23 to 38 years with IST and 10 age- and sex-matched control subjects were assessed with the following autonomic function tests: (1) sympathovagal balance to the sinus node assessed by calculating the LF\/HF (low frequency\/high frequency) ratio using power spectral analysis both in the supine position and after 10 minutes of head-up tilt to 60 degrees, (2) cardiovagal reflex assessed by cold face test (CFT), (3) beta-adrenergic sensitivity as determined by calculating isoproterenol dose-response curves and isoproterenol chronotropic dose 25 (CD25), and (4) intrinsic heart rate (IHR) assessed after autonomic blockade with atropine 0.04 mg\/kg and propranolol 0.2 mg\/kg administered as an intravenous bolus. No significant differences in the LF\/HF ratio both in the supine position (2.8 +\/- 0.3 versus 2.6 +\/- 0.4) and during upright tilt (8.7 +\/- 1.3 versus 8.5 +\/- 0.5) were observed between control subjects and IST patients. Cardiovagal response to CFT was markedly depressed in all patients (6.3% IST patients versus 24.2% control subjects, P &lt; .001). beta-Adrenergic hypersensitivity to isoproterenol was noted in all patients (mean CD25, 0.29 +\/- 0.10 microgram IST patients versus 1.27 +\/- 0.4 microgram control subjects; P &lt; .001), and high IHR was noted in all cases. The patients were treated with high doses of beta-blockers with adequate short-term control. Radiofrequency catheter ablation of the sinus node area was performed in one drug-refractory patient.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>CONCLUSIONS<\/jats:title>\n                    <jats:p>These findings suggest that the mechanism leading to IST is related to a primary sinus node abnormality characterized by a high IHR, depressed efferent cardiovagal reflex, and beta-adrenergic hypersensitivity.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1161\/01.cir.90.2.873","type":"journal-article","created":{"date-parts":[[2012,6,11]],"date-time":"2012-06-11T20:34:42Z","timestamp":1339446882000},"page":"873-877","update-policy":"https:\/\/doi.org\/10.1161\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":148,"title":["Mechanism of 'inappropriate' sinus tachycardia. Role of sympathovagal balance."],"prefix":"10.1161","volume":"90","author":[{"given":"C A","family":"Morillo","sequence":"first","affiliation":[{"name":"Department of Medicine, University of Western Ontario, London, Canada."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"G J","family":"Klein","sequence":"additional","affiliation":[{"name":"Department of Medicine, University of Western Ontario, London, Canada."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"R K","family":"Thakur","sequence":"additional","affiliation":[{"name":"Department of Medicine, University of Western Ontario, London, Canada."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"H","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Medicine, University of Western Ontario, London, Canada."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"M","family":"Zardini","sequence":"additional","affiliation":[{"name":"Department of Medicine, University of Western Ontario, London, Canada."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"R","family":"Yee","sequence":"additional","affiliation":[{"name":"Department of Medicine, University of Western Ontario, London, Canada."}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"276","container-title":["Circulation"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.ahajournals.org\/doi\/pdf\/10.1161\/01.CIR.90.2.873","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2024,5,12]],"date-time":"2024-05-12T11:48:32Z","timestamp":1715514512000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.ahajournals.org\/doi\/10.1161\/01.CIR.90.2.873"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1994,8]]},"references-count":0,"journal-issue":{"issue":"2","published-print":{"date-parts":[[1994,8]]}},"alternative-id":["10.1161\/01.CIR.90.2.873"],"URL":"https:\/\/doi.org\/10.1161\/01.cir.90.2.873","relation":{},"ISSN":["0009-7322","1524-4539"],"issn-type":[{"value":"0009-7322","type":"print"},{"value":"1524-4539","type":"electronic"}],"subject":[],"published":{"date-parts":[[1994,8]]},"assertion":[{"value":"1994-08-01","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}