title: Effect of systolic blood pressure and carotid stiffness on baroreflex gain in elderly subjects.
abstract: BACKGROUND
  Aging is associated with diminished baroreflex sensitivity (gain), which predisposes elderly people to orthostatic hypotension, syncope, and cardiovascular morbidity. Aging is also associated with systolic blood pressure (SBP) elevation and carotid artery stiffness, which may both affect baroreflex gain.
  
  
  METHODS
  We examined the relation between SBP, carotid artery stiffness, and baroreflex gain in 34 healthy elderly (71 +/- 4 years) and 10 healthy young (31 +/- 3 years) subjects. SBP (Finapres) and carotid artery stiffness (ultrasound measures of relative carotid artery diameter changes during each blood pressure pulse) were measured. The gain of the transfer function relating the R-R interval to SBP fluctuations at a frequency of 0.05-0.15 Hz was used to assess cardiovagal baroreflex gain.
  
  
  RESULTS
  Elderly subjects had higher carotid artery stiffness (14.2 +/- 5.1 vs 6.6 +/- 1.8, p <.05), higher SBP (146 +/- 24 vs 125 +/- 8 mmHg, p =.012), and lower baroreflex gain (8.2 +/- 6.4 vs 16.3 +/- 7.4, p <.05) than young subjects. Among all subjects, SBP and carotid artery stiffness both correlated with baroreflex gain (r = -.39, p =.02 for both). Although SBP was related to stiffness across all subjects, this relation was not present among the elderly subjects. Within the elderly group, only SBP was independently related to baroreflex gain (R(2) =.51, p =.009).
  
  
  CONCLUSIONS
  SBP elevation in elderly people may affect the neural or cardiac response to blood pressure fluctuations, independent of the mechanical properties of barosensory regions in the carotid artery. Future studies should examine the effect of pharmacologic treatment of hypertension on baroreflex gain in elderly people.
authors.affiliation: Research and Training Institute, Hebrew Rehabilitation Center for Aged, Gerontology Division, Beth Israel Deaconess Medical Center, and Division on Aging, Harvard Medical School, Boston, Massachusetts 02131, USA.
authors.forename: Seiji
authors.initials: S
authors.lastname: Mukai
authors.forename: Margaret
authors.initials: M
authors.lastname: Gagnon
authors.forename: Ikechukwu
authors.initials: I
authors.lastname: Iloputaife
authors.forename: Jason W
authors.initials: JW
authors.lastname: Hamner
authors.forename: Lewis A
authors.initials: LA
authors.lastname: Lipsitz
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology*; D002339:Carotid Arteries / Q000502:physiology*; D004548:Elasticity; D006801:Humans; D013599:Systole