title: Head-up tilt testing potentiated with low-dose sublingual isosorbide dinitrate: a simplified time-saving approach for the evaluation of unexplained syncope.
abstract: BACKGROUND
  Head-up tilt testing is widely used in the clinical assessment of patients with unexplained syncope. However, the lack of a standard methodology and the conflicting results concerning sensitivity and specificity of the procedure have prompted further studies to define a more cost-effective approach for tilt testing.
  
  
  OBJECTIVE
  Our clinical investigation was undertaken to assess the diagnostic value in unexplained syncope of a simple and time-saving protocol for head-up tilt testing, including low-dose sublingual isosorbide dinitrate administration.
  
  
  METHODS
  A group of 73 consecutive patients (43 women and 30 men, mean age 39.6+/-21.8 years) with unexplained syncope despite conventional clinical cardiovascular and neurologic assessment and 10 asymptomatic control subjects underwent head-up tilt testing with isosorbide dinitrate challenge. Participants were tilted at 60 degrees for 30 minutes without medication; if no symptoms occurred, 1.25 mg of isosorbide dinitrate was administered sublingually and tilting was continued for an additional 15 minutes.
  
  
  RESULTS
  During the drug-free phase of the test 14 (19.2%) patients had syncope. After isosorbide dinitrate administration syncope occurred in another 28 patients (38.3%); minor symptoms in association with hypotension developed in 10 (13.7%) patients. The test result was negative in all control subjects. The positive rate and specificity of head-up tilt testing with isosorbide dinitrate provocation were 57.5% and 100%, respectively.
  
  
  CONCLUSIONS
  This new practical diagnostic procedure was found to be fairly sensitive and clearly specific in inducing a vasovagal reflex in patients with syncope of uncertain origin. Consequently, such approach could give a significant contribution in the diagnostic workup of these patients.
authors.affiliation: Department of Heart Diseases, S. Filippo Neri Hospital, Rome, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Ammirati
authors.forename: F
authors.initials: F
authors.lastname: Colivicchi
authors.forename: A
authors.initials: A
authors.lastname: Biffi
authors.forename: B
authors.initials: B
authors.lastname: Magris
authors.forename: C
authors.initials: C
authors.lastname: Pandozi
authors.forename: M
authors.initials: M
authors.lastname: Santini
mesh_terms: D000286:Administration, Sublingual; D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D001919:Bradycardia / Q000139:chemically induced / Q000503:physiopathology; D003937:Diagnosis, Differential; D004305:Dose-Response Relationship, Drug; D015150:Echocardiography, Doppler; D015716:Electrocardiography, Ambulatory; D004569:Electroencephalography; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007022:Hypotension / Q000139:chemically induced / Q000503:physiopathology; D007548:Isosorbide Dinitrate / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D011187:Posture; D012680:Sensitivity and Specificity; D013575:Syncope / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D013997:Time Factors; D014665:Vasodilator Agents / Q000008:administration & dosage*
chemical_list: D014665:Vasodilator Agents; D007548:Isosorbide Dinitrate