Value of sublingual isosorbide dinitrate before isoproterenol tilt test for diagnosis of neurally mediated syncope.
Head-up tilt-table test is valuable in diagnosing type of syncope. Sensitivity varies in reports and is mostly poor. Isoproterenol or nitroglycerin is regularly used to increase head-up tilt-table test sensitivity. The aim of this study was to assess the value of sublingual isosorbide dinitrate administration before isoproterenol tilt test as a simple, practical test for diagnosis of neurally mediated syncope. Ninety-six patients (45 men and 51 women, mean age 42.5 years) with recurrent (median 4 times) loss of consciousness that remained unexplained after clinical and noninvasive assessment and 72 healthy volunteers (36 men and 36 women, mean age 40.1 years) were randomly divided into groups: isosorbide-isoproterenol test and isoproterenol test. During isosorbide-isoproterenol test, a positive response (syncope in association with sudden hypotension or bradycardia) occurred in 35 patients (72.9%) with unexplained syncope, an exaggerated response (minor symptoms in association with slowly increasing hypotension alone) occurred in 7 (14.6%), a negative response in 2 (4.2%), and drug intolerance in 4 (8.3%). During isoproterenol testing, these percentages were 52.1%, 16.7%, 25.0%, and 6.2%, respectively. Only 3 control volunteers (8.3%) had a positive response to isosorbide-isoproterenol test and 2 (5.6%) to isoproterenol test. The duration of the test and the time for syncope induction in the isosorbide-isoproterenol test were shorter than those in the isoproterenol test (24.84 +/- 5.15 vs 35.70 +/- 6.28 minutes [p <0.01]; 4.53 +/- 2.86 vs 6.27 +/- 4.11 minutes [p <0.05]). This study concluded that isosorbide-isoproterenol test could be valuable in diagnosing unexplained syncope for its high sensitivity, powerful specificity, and short duration.
Zeng
C
C
Hypertension Center and Division of Cardiology, Daping Hospital, Third Military Medical University, Chongqing, People's Republic of China.
Zhu
Z
Z
Hu
W
W
Liu
G
G
Zhu
S
S
Zhou
Y
Y
Shi
W
W
D000286:Administration, Sublingual; D000328:Adult; D001794:Blood Pressure; D005260:Female; D006339:Heart Rate; D006801:Humans; D007545:Isoproterenol; D007548:Isosorbide Dinitrate / Q000008:administration & dosage; D008297:Male; D012680:Sensitivity and Specificity; D013566:Sympathomimetics; D019462:Syncope, Vasovagal / Q000175:diagnosis* / Q000503:physiopathology; D018667:Tilt-Table Test; D014665:Vasodilator Agents / Q000008:administration & dosage
D013566:Sympathomimetics; D014665:Vasodilator Agents; D007548:Isosorbide Dinitrate; D007545:Isoproterenol