title: MR and applanation tonometry derived aortic impedance: association with aging and left ventricular remodeling.
abstract: OBJECTIVE
  We sought to noninvasively estimate aortic impedance indices from MR and tonometric data.
  
  
  METHODS
  MR aortic velocity-encoded and carotid applanation tonometry pressure data of 70 healthy subjects (19-79 years) were used to calculate the following indices from impedance spectrum: (i) characteristic impedance (Zc) reflecting pulsatile component of left ventricular (LV) afterload, (ii) frequency of the minimal impedance magnitude related to arterial compliance (FMIN ), (iii) total peripheral resistance (TPR) related to steady LV load, (iv) impedance oscillatory index (ZINDEX ) related to proximal reflections, and (v) reflection magnitude (RM). Associations with age and LV remodeling (LV mass/end-diastolic volume) were investigated using multivariate analysis.
  
  
  RESULTS
  All indices except Zc were associated with age independent of subjects characteristics and systolic blood pressures. They were all significantly associated with the well-established carotid-femoral pulse wave velocity (r ≥ 0.29; P < 0.01). However, such associations were not independent of age. Pulsatile index Zc was independently associated with carotid pulse pressure (r = 0.53, P < 0.001). Moreover, conversely to conventional stiffness indices, Zc and TPR were independently associated with LV remodeling (r = 0.30, r = 0.43, respectively, P < 0.01).
  
  
  CONCLUSIONS
  We estimated aortic impedance from velocity-encoded MR and tonometry data resulting in reliable impedance and reflection indices as confirmed by their significant and independent associations with age and LV remodeling.
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, UMR 7371, UMR_S 1146, Laboratoire d'Imagerie Biomédicale, Paris, France; INSERM, UMR_S 1146, Laboratoire d'Imagerie Biomédicale, Paris, France; CNRS, UMR 7371, Laboratoire d'Imagerie Biomédicale, Paris, France.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Bargiotas
authors.forename: Emilie
authors.initials: E
authors.lastname: Bollache
authors.forename: Elie
authors.initials: E
authors.lastname: Mousseaux
authors.forename: Alain
authors.initials: A
authors.lastname: Giron
authors.forename: Alain
authors.initials: A
authors.lastname: de Cesare
authors.forename: Alban
authors.initials: A
authors.lastname: Redheuil
authors.forename: Nadjia
authors.initials: N
authors.lastname: Kachenoura
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001011:Aorta / Q000503:physiopathology*; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure; D017097:Electric Impedance; D005260:Female; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008365:Manometry / Q000379:methods / Q000706:statistics & numerical data; D008875:Middle Aged; D020257:Ventricular Remodeling / Q000502:physiology*; D055815:Young Adult
keywords: aortic impedance; left ventricular remodeling; magnetic resonance imaging; reflections