title: Preserved parasympathetic cardiac innervation after atrioventricular node modification: evidence from circle maps of respiratory sinus arrhythmia.
abstract: BACKGROUND
  Respiratory sinus arrhythmia (RSA) and heart rate variability (HRV) are parameters of autonomic cardiac innervation. They decrease with age and after atrioventricular nodal modification (AVNM) suggesting vagal denervation in both situations. We hypothesized, however, that AVNM causes only a transient, functional decline in vagal activity, whereas aging causes permanent vagal denervation. A new method of analyzing RSA phase dynamics based on circle maps (CM) can potentially differentiate between both forms of reduced vagal activity.
  
  
  METHODS
  In 18 younger and 14 older healthy control subjects 24-hour Holter ECGs were recorded for HRV analysis. Repeated measurements of RSA were acquired during paced breathing (PB). In 16 consecutive patients undergoing AVNM the same measurements were applied before, 1 day and 3 months after the procedure. CM were calculated from consecutive RR intervals and the similarity between different CM quantified by the Kullback information gain (KIG).
  
  
  RESULTS
  HRV analysis revealed lower HF bands, LF bands and RSA amplitudes in older vs. younger control subjects. KIG revealed less similarity between younger and older control subjects than within the respective age groups. After AVNM a decrease in HF bands was noted in HRV analysis. Three months after AVNM, HF bands returned to pre-ablation values. CM obtained before and 1 day after AVNM displayed comparable similarity to CM acquired 1 day before and 3 months after ablation.
  
  
  CONCLUSIONS
  In contrast to conventional HRV parameters, CM of RSA are not altered by ablation in the posteroseptal space but by aging. Thus, this new method appears to differentiate between transient autonomic modification and chronic denervation.
authors.affiliation: Department of Cardiology and Internal Medicine, University Hospital Aachen, Aachen, Germany. mzarse@ukaachen.de
authors.forename: Markus
authors.initials: M
authors.lastname: Zarse
authors.forename: Kai Ulf
authors.initials: KU
authors.lastname: Markus
authors.forename: Michael
authors.initials: M
authors.lastname: Schiek
authors.forename: Patrick
authors.initials: P
authors.lastname: Schauerte
authors.forename: Anil Martin
authors.initials: AM
authors.lastname: Sinha
authors.forename: Friedhelm
authors.initials: F
authors.lastname: Drepper
authors.forename: Horst
authors.initials: H
authors.lastname: Halling
authors.forename: Peter
authors.initials: P
authors.lastname: Hanrath
authors.forename: Christoph
authors.initials: C
authors.lastname: Stellbrink
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology; D001146:Arrhythmia, Sinus / Q000503:physiopathology; D001283:Atrioventricular Node / Q000503:physiopathology*; D015716:Electrocardiography, Ambulatory; D005260:Female; D005726:Ganglia, Parasympathetic / Q000503:physiopathology*; D006321:Heart / Q000294:innervation*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012119:Respiration; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000503:physiopathology* / Q000601:surgery*