title: The vascular impact of aging and vasoactive drugs: comparison of two digital volume pulse measurements.
abstract: BACKGROUND
  Indices of pressure wave reflection (RI(DVP)) and large artery stiffness (SI(DVP)) can be derived from the digital volume pulse (DVP). Indices obtained from the second derivative of the DVP have also been proposed to characterize vascular aging and effects of vasoactive drugs.
  
  
  METHODS
  We compared RI(DVP) and SI(DVP) with the indices a/b, a/c, a/d, and a/e calculated from sequential peaks of the second derivative of the DVP in 124 healthy men. The DVP was obtained by measuring infrared light transmission through the finger. In 10 men measurements were obtained at baseline and during intravenous infusion of glyceryl trinitrate (GTN, 3 to 300 microg/min) and, on separate occasions, angiotensin II (AII, 75 to 300 microg/min) and saline vehicle.
  
  
  RESULTS
  SI(DVP) was strongly associated with age (R = 0.63, P <.001) but little influenced by AII or GTN. RI(DVP) was weakly associated with age but showed a consistent dose-dependent increase during AII and a decrease during GTN. d/a was strongly associated with age (R = -0.66, P <.001), influenced by vasoactive drugs but did not change in a dose-dependent manner during GTN. Other second derivative indices were less strongly correlated with age and showed an inconsistent response to vasoactive drugs. Within subject standard deviations of SI(DVP) and d/a for measurements on different occasions were 2.1 and 5.4 "years of vascular aging" respectively.
  
  
  CONCLUSIONS
  In healthy men, RI(DVP) may be a more reliable index of the effects of vasoactive drugs than d/a. SI(DVP) is similarly associated with age as is d/a, but less variable and may thus be a better index of vascular aging.
authors.affiliation: Department of Clinical Pharmacology, St. Thomas' Hospital, Centre for Cardiovascular Biology and Medicine, King's College, London, United Kingdom.
authors.forename: Sandrine C
authors.initials: SC
authors.lastname: Millasseau
authors.forename: Ronan P
authors.initials: RP
authors.lastname: Kelly
authors.forename: James M
authors.initials: JM
authors.lastname: Ritter
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Chowienczyk
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D000804:Angiotensin II / Q000008:administration & dosage; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D001811:Blood Volume Determination / Q000379:methods / Q000592:standards; D005385:Fingers; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D005996:Nitroglycerin / Q000008:administration & dosage*; D010991:Plethysmography / Q000379:methods* / Q000592:standards; D015203:Reproducibility of Results; D014662:Vasoconstrictor Agents / Q000008:administration & dosage; D014665:Vasodilator Agents / Q000008:administration & dosage*
chemical_list: D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D000804:Angiotensin II; D005996:Nitroglycerin