title: Effects of pacing modes on cardiac baroreflex function in permanently paced patients with sinus node dysfunction.
abstract: OBJECTIVE
  We compared, in patients with sick sinus syndrome, the effects of various pacing modes on baroreceptor (BR)-stroke volume (SV) reflex sensitivity, a method we have closely correlated with BR-heart rate (HR) reflex sensitivity.
  
  
  BACKGROUND
  Impaired autonomic nervous function, such as decreased BR-HR reflex sensitivity, predicts sudden cardiac death. However, in patients with sick sinus syndrome, the effects of various pacing modes on autonomic function are unknown, since chronotropic incompetence precludes its evaluation by measurements of BR-HR reflex sensitivity.
  
  
  METHODS
  We studied 12 recipients of dual-chamber pacemakers with sick sinus syndrome (mean age = 73 +/- 8 years; 8 men). Beat-by-beat blood pressure (BP) and SV were measured during 5-minute runs of AAI, DDD, and VVI pacing, and spectrally analyzed to assess BR-SV reflex sensitivity.
  
  
  RESULTS
  Systolic BP was significantly lower (P < 0.01) during VVI (109 +/- 24 mmHg) than during DDD (124 +/- 22 mmHg) or AAI (125 +/- 41 mmHg) pacing. SV was significantly smaller during VVI (36 +/- 23 mL) than during DDD (49 +/- 31 mL) pacing (P < 0.05). BR-SV reflex sensitivity was significantly lower (P < 0.05) during VVI (9.3 +/- 5.7% per mmHg) than during DDD (15.0 +/- 6.5% per mmHg) or AAI (15.5 +/- 6.2% per mmHg) pacing.
  
  
  CONCLUSIONS
  BR-SV reflex sensitivity was significantly lower during VVI than during AAI or DDD pacing. Atrioventricular synchrony plays an important role in the preservation of BR-SV reflex sensitivity in pacemaker recipients.
authors.affiliation: The Second Department of Internal Medicine, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan.
authors.forename: Takuo
authors.initials: T
authors.lastname: Tsurugi
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Abe
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Oginosawa
authors.forename: Ritsuko
authors.initials: R
authors.lastname: Kohno
authors.forename: Tomiya
authors.initials: T
authors.lastname: Yasumasu
authors.forename: Toshihisa
authors.initials: T
authors.lastname: Nagatomo
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Otsuji
mesh_terms: D000368:Aged; D017704:Baroreflex; D001794:Blood Pressure; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D010138:Pacemaker, Artificial; D012804:Sick Sinus Syndrome / Q000503:physiopathology* / Q000517:prevention & control*; D013318:Stroke Volume; D016896:Treatment Outcome