title: Safety and tolerability of an aggressive tilt table test protocol in the evaluation of patients with suspected neurocardiogenic syncope.
abstract: Safety and tolerability of a one-step tilt table test with high dose (5 micrograms/min) isoproterenol (ISO) without intermediate stages were evaluated in a symptomatic population of 300 patients referred for clinical syncope, near syncope, or dizziness. ISO has been used as a provocative test but remains controversial. A population of 118 male and 182 female patients with a mean age of 45 (range 5-90) years underwent 300 tests. Heart rate and blood pressure were monitored continuously. A positive test was one in which clinical symptoms were reproduced or hemodynamic criteria met. Patients were initially supine for 5 minutes followed by head upright tilt (HUT) to an angle of 80 degrees for 10 minutes. Negative tests were repeated with an infusion of ISO at a rate of 5 micrograms/min. HUT was positive in 133 (44.3%) of 300 tests. With a 10-minute HUT alone, only 17 (5.7%) of 300 of tests were positive. Of the initial negative tests, 273 of 283 were tested with ISO. With ISO, 116 (42.5%) of 273 were positive. ISO in high dose (5 micrograms/min) was used in 264 of 273 patients, while low dose (1.0-2.5 micrograms/min) was used in 9 of 273 under special circumstances. High dose ISO was tolerated in 164 (62.1%) of 264 patients, reduced in 87 (33%) of 264, and discontinued in 11 (4.2%) of 264. Reasons for reduction included tachycardia (40 patients), nausea (31 patients), chest pain (2 patients), arrhythmia (5 patients), or other (9 patients). Adverse effects resolved within 1 minute of dose reduction. This one-step high dose ISO protocol reproduced neurocardiogenic syncope in symptomatic patients who tested negative without ISO and was safe, tolerated, and expeditious.
authors.affiliation: Department of Medicine, State University of New York at Stony Brook, New York, USA.
authors.forename: S C
authors.initials: SC
authors.lastname: Vlay
authors.forename: C
authors.initials: C
authors.lastname: Brodsky
authors.forename: L C
authors.initials: LC
authors.lastname: Vlay
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D004305:Dose-Response Relationship, Drug; D004342:Drug Hypersensitivity / Q000209:etiology / Q000503:physiopathology; D004562:Electrocardiography / Q000187:drug effects; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D007262:Infusions, Intravenous; D007545:Isoproterenol / Q000008:administration & dosage / Q000009:adverse effects; D008297:Male; D008790:Metoprolol / Q000008:administration & dosage / Q000009:adverse effects; D008875:Middle Aged; D011379:Prognosis; D012449:Safety; D013565:Sympatholytics / Q000008:administration & dosage / Q000009:adverse effects; D013566:Sympathomimetics / Q000008:administration & dosage / Q000009:adverse effects; D019462:Syncope, Vasovagal / Q000175:diagnosis* / Q000503:physiopathology; D018667:Tilt-Table Test / Q000379:methods*
chemical_list: D013565:Sympatholytics; D013566:Sympathomimetics; D008790:Metoprolol; D007545:Isoproterenol