title: Effect of caffeine on aortic elastic properties and wave reflection.
abstract: OBJECTIVE
  Caffeine is the most widely used pharmacologically active substance. Aortic elastic properties and arterial wave reflection are important factors for the efficient performance of the cardiovascular system, as well as prognosticators of cardiovascular risk. We investigated the effect of caffeine on aortic elastic properties and wave reflection.
  
  
  METHODS
  We studied the effect of caffeine (250 mg) in 20 healthy subjects according to a randomized, placebo-controlled, double-blind, cross-over design.
  
  
  METHODS
  Aortic stiffness was evaluated with carotid-femoral pulse wave velocity and wave reflection with augmentation index of the aortic pressure waveform.
  
  
  RESULTS
  Pulse wave velocity increased (by 0.51 m/s, 0.001) denoting an increase in aortic stiffness. Augmentation index and augmented pressure increased (by 6.8%, and by 4.4 mmHg, respectively, P <0.001 for both) denoting increased wave reflections. Concurrently, both radial and aortic systolic, diastolic and pulse pressure increased significantly. However, this increase was 20 and 9% larger for aortic systolic pressure (at 30 and 60 min, P <0.001 and P <0.05, respectively) and 56% larger for aortic pulse pressure (at 30 min, P <0.001) compared with the corresponding upper limb values. This indicates that peripheral pressure measurements are not an accurate guide for the pressor effect of caffeine in central arteries.
  
  
  CONCLUSIONS
  Caffeine affects unfavorably aortic stiffness and enhances wave reflections. This finding has implications for the impact of caffeine consumption on cardiovascular risk.
authors.affiliation: Medical Professorial Unit, St. Vincent's Hospital and Clinic, University of New South Wales, Sydney, Australia. cvlachop@otenet.gr
authors.forename: Charalambos
authors.initials: C
authors.lastname: Vlachopoulos
authors.forename: Kozo
authors.initials: K
authors.lastname: Hirata
authors.forename: Michael F
authors.initials: MF
authors.lastname: O'Rourke
mesh_terms: D000328:Adult; D000368:Aged; D001011:Aorta / Q000187:drug effects* / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects; D002110:Caffeine / Q000009:adverse effects*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004548:Elasticity; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged
chemical_list: D002110:Caffeine