Heart rate and blood pressure patterns observed in head-up tilt table testing

Shown are the heart rate and blood pressure responses seen during tilt table testing in patients with various etiologies of syncope, including autonomic failure, neurally mediated syncope, and postural tachycardia syndrome (POTS). The absence of an appropriate reflex-induced increase in heart rate as the blood pressure falls is a useful clue to the presence of autonomic failure. During neurally mediated syncope, parasympathetic (vagal) activity increases as blood pressure declines, slowing the heart. With POTS, tilt table testing typically reproduces the clinical symptoms in association with a heart rate increase ≥30 beats/min or a maximum heart rate ≥120 beats/min within the first 10 minutes; these changes are not associated with hypotension.