Figure 8. Delayed orthostatic hypotension, carotid sinus hypersensitivity and vasovagal reflex. Head-up tilt test performed on 65-yearold- man with unexplained syncope. Please, note a progressive decrease in blood pressure after tilt-up (- 30 mmHg ), positive carotid sinus massage right side with symptom reproduction (dizziness) and finally positive nitroglycerine provocation with syncope. Cerebral oximetry (normal values: 60-80%) measured through near-infrared spectroscopy demonstrates only a slight progressive fall. CSM dx, carotid sinus massage right side; NTG, nitroglycerine 400 μg sublingually.