title: Aortic distensibility after aortic root replacement assessed with cardiovascular magnetic resonance.
abstract: OBJECTIVE
  The changes in geometry of the aortic root during the cardiac cycle are thought to be essential for optimal valve function, both in terms of leaflet stress and dynamic behavior. Using cardiac magnetic resonance (CMR), the study aim was to determine aortic root distensibility of the homograft (group H) and the Medtronic Freestyle xenograft (group F) after aortic root replacement, from a prospective randomized trial.
  
  
  METHODS
  CMR was performed in 15 patients (six homografts, nine Freestyle) at six months and one year after surgery. Percentage change in aortic radius (PCR) and pressure strain elastic modulus (PSEM) were measured as indices of distensibility, and results related to left ventricular mass (LVM).
  
  
  RESULTS
  At six months after surgery, mean PCR was 12+/-2.5 in group H and 12.9+/-6.1 in group F (p = NS), and PSEM was 428.5+/-69.8 and 493.5+/-72.7 g/cm2, respectively (p = NS). PCR was reduced to 10+/-1.7% in group H, and by 8.5+/-2.8% in group F (p = NS), while PSEM was increased to 520.5+/-87.3 and 825+/-420.4, respectively (p = NS) at the one-year follow up. Regression analysis showed a correlation between PCR and LVM (r = 0.52, p = 0.08) and LVM index (r = 0.46, p = 0.14), respectively. In addition, there was a relationship between PSEM, LVM and LVM index, suggesting that the stiffer the root wall, the higher the postoperative LVM.
  
  
  CONCLUSIONS
  Up to one year after aortic root replacement, the wall of both the allogenic and xenogenic valves retained near-normal distensibility. For the first time, a correlation was demonstrated between the elastic properties of the aortic root and LVM. The longer-term behavior and clinical implications of these findings require further investigation.
authors.affiliation: Academic Department of Cardiothoracic Surgery and Cardiovascular MR Unit, NHLI, The Royal Brompton & Harefield NHS Trust, London, UK.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Melina
authors.forename: Kim
authors.initials: K
authors.lastname: Rajappan
authors.forename: Mohamed
authors.initials: M
authors.lastname: Amrani
authors.forename: Asghar
authors.initials: A
authors.lastname: Khaghani
authors.forename: Dudley J
authors.initials: DJ
authors.lastname: Pennell
authors.forename: Magdi H
authors.initials: MH
authors.lastname: Yacoub
mesh_terms: D000368:Aged; D001021:Aortic Valve / Q000473:pathology; D001705:Bioprosthesis; D004548:Elasticity; D005260:Female; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000175:diagnosis; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D016032:Randomized Controlled Trials as Topic; D016896:Treatment Outcome; D016277:Ventricular Function, Left