Specificity of head-up tilt testing in adolescents: effect of various degrees of tilt challenge in normal control subjects.
Level 4 - case-series / case-control
Cross-sectional diagnostic physiological challenge in healthy controls without a clinical comparator cohort.
PubMed 9316539 · doi:10.1016/s0735-1097(97)00255-6
What was done
Sixty-nine healthy volunteers aged 12 to 18 years (38 male, 31 female) with no history of syncope, presyncope, or arrhythmia were evaluated to determine the specificity of tilt protocols in adolescents. Subjects first underwent autonomic maneuvers (deep breathing, carotid massage, Valsalva maneuver, diving reflex) and were then tilted to 80 degrees (n = 10), 70 degrees (n = 31), or 60 degrees (n = 28) for up to 30 minutes on a motorized table with a footboard.
What was found
Presyncope or frank syncope occurred in 24 of 69 healthy subjects (35%): 6 of 10 (60%) at 80 degrees, 9 of 31 (29%) at 70 degrees, and 9 of 28 (32%) at 60 degrees (the 80-degree protocol was stopped early by the institutional review board). The mean time to a positive response was 10.5 min at 80 degrees, 14.2 min at 70 degrees, and 13.2 min at 60 degrees. Within the first 10 minutes, positive responses occurred in 4 of 10 (80 degrees), 3 of 31 (70 degrees), and 2 of 28 (60 degrees). Baseline ECG intervals, vitals, and autonomic maneuver responses did not differ between tilt-positive and tilt-negative subjects.
Why it matters
Standard adult tilt protocols produce high false-positive rates in healthy adolescents. Restricting tilt testing to 60 or 70 degrees for no longer than 10 minutes achieves specificity greater than 85% in teenage patients.
Limits
The total sample size was modest, with small subgroup sizes (especially 80 degrees, n = 10, resulting in statistical power of 0.45 for detecting differences between tilt angles). The study only tested healthy controls and did not evaluate symptomatic patients to measure diagnostic sensitivity.
Cited by
- supports A tilt table test for autonomic response involves strapping a patient to a table and raising them to approximately 70 degrees while monitoring cardiovascular response.