Spontaneous vs nitroglycerin-induced vasovagal reflex on head-up tilt : Are there neuroendocrine differences?
Background Head-up tilt test (HUT) has been used for nearly 30 years for diagnosing vasovagal syncope (VVS) and was enhanced by sublingual nitroglycerin (glyceryl trinitrate [GTN]) challenge in the 1990s. Objective The purpose of this study was to explore neuroendocrine differences between spontaneous and drug-induced HUT positivity. Methods Two hundred eighty-eight patients (41.3% male, age 49 ±