Inappropriate sinus tachycardia complicated by vasodepressor syncope. The average HR was above 100 BPM with the maximal heart rate 149 BPM during the supine position. The tilt provoked HR increase and marked oscillations in all signals including HR, BP, and CBFv. At the 5th minute of the tilt, BP suddenly declined (black arrow) that was accompanied by tachycardia 179 BPM culminated in a syncope. The decline in BP without bradycardia is characteristic of vasodepressor syncope due to reduced peripheral resistance. CBFv declined and the pulsatility index (systolic CBFv – diastolic CBFv) increased (blue arrows) that indicates cerebral vasodilation. Data from 26-year-old woman.