title: The changes of heart rate variability after unilateral stellate ganglion block.
abstract: BACKGROUND
  The effect of the unilateral stellate ganglion block (SGB) on cardiovascular regulation remains controversial. We wished to evaluate the changes in heart rate variability (HRV) after a unilateral stellate ganglion block in patients with head and neck pain in the present study.
  
  
  METHODS
  Patients with head and neck pain (n = 89) were studied. HRV was determined before and after a C6 unilateral stellate ganglion block (right-sided SGB, 40; left-sided SGB, 49) using a paratracheal technique with 1% mepivacaine (6 ml).
  
  
  RESULTS
  There were no significant differences in HRV indices before and after right-sided SGB. The log scale of power in the high frequency range (lnHF) was increased and ratio of power in the low frequency range (LF) to power in the high frequency range (HF) ratio was decreased after left-sided SGB.
  
  
  CONCLUSIONS
  These results demonstrated that left-sided SGB increased parasympathetic activities in patients with head and neck pain.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Ewha Womans University School of Medicine, Seoul, Korea.
authors.forename: Jang Jae
authors.initials: JJ
authors.lastname: Kim
authors.forename: Rack Kyung
authors.initials: RK
authors.lastname: Chung
authors.forename: Hee Seung
authors.initials: HS
authors.lastname: Lee
authors.forename: Jong In
authors.initials: JI
authors.lastname: Han