Postural tachycardia syndrome was associated with higher somatic vigilance (P=0.0167), more anxiety (P<0.0001), and pronounced anticipatory tachycardia (P=0.015) compared to matched controls.
Cross-Sectional (n=49)
Is fear conditioning associated with tachycardia and cerebral hypoperfusion in patients with postural tachycardia syndrome?
Postural tachycardia syndrome may involve a fear-conditioned hyperadrenergic state when standing, driven by heightened somatic anxiety and epinephrine secretion.
p-value: p=0.015
Despite its increasing recognition and extensive research, there is no unifying hypothesis on the pathophysiology of the postural tachycardia syndrome. In this cross-sectional study, we examined the role of fear conditioning and its association with tachycardia and cerebral hypoperfusion on standing in 28 patients with postural tachycardia syndrome (31 ± 12 years old, 25 females) and 21 matched controls. We found that patients had higher somatic vigilance (P = 0.0167) and more anxiety (P < 0.0001). They also had a more pronounced anticipatory tachycardia right before assuming the upright position in a tilt-table test (P = 0.015), a physiological indicator of fear conditioning to orthostasis. While standing, patients had faster heart rate (P < 0.001), higher plasma catecholamine levels (P = 0.020), lower end-tidal CO2 (P = 0.005) and reduced middle cerebral artery blood flow velocity (P = 0.002). Multi-linear logistic regression modelling showed that both epinephrine secretion and excessive somatic vigilance predicted the magnitude of the tachycardia and the hyperventilation. These findings suggest that the postural tachycardia syndrome is a functional disorder in which standing may acquire a frightful quality, so that even when experienced alone it may elicit a fearful conditioned response. Heightened somatic anxiety is associated with and may predispose to a fear-conditioned hyperadrenergic state when standing. Our results have therapeutic implications.
Norcliffe‐Kaufmann et al. (Fri,) conducted a cross-sectional in postural tachycardia syndrome (n=49). Tilt-table test (orthostasis) vs. Matched controls was evaluated on anticipatory tachycardia right before assuming the upright position (p=0.015). Postural tachycardia syndrome was associated with higher somatic vigilance (P=0.0167), more anxiety (P<0.0001), and pronounced anticipatory tachycardia (P=0.015) compared to matched controls.