title: Systolic flow displacement using 3D magnetic resonance imaging in an experimental model of ascending aorta aneurysm: impact of rheological factors.
abstract: OBJECTIVE
  The impact of systolic flow displacement on the development and progression of ascending aorta dilatation in aortic valve disease is a matter of controversy. Our objective was to study the association between rheological stimuli and development of aortic dilatation in a large animal model of supravalvular aortic stenosis and eccentric flow.
  
  
  METHODS
  Twenty-four pigs weighing 10-14 kg were randomly allocated (ratio 2:1) to either restrictive ascending aortic banding or sham operation. Aortic diameter and systolic flow displacement were assessed by three-dimensional phase-contrast magnetic resonance imaging at 6 and 18 weeks after surgery. Twenty pigs (n = 14, banded vs n = 6, sham) completed full imaging protocol and were included in the analysis. After the last follow-up, a subset of 14 animals was sacrificed for histological analysis.
  
  
  RESULTS
  All banded animals developed significant progressive aortic dilatation both at 6 and 18 weeks, compared with sham-operated pigs: 34.3 ± 4.8 vs 21.4 ± 2.7 mm at 6 weeks (P < 0.001); and 50.0 ± 8.4 vs 38.0 ± 8.3 mm at 18 weeks (P = 0.002). The peak gradient at 6 weeks showed a trend to positively correlate with aortic diameter at 18 weeks (R = 0.50, P = 0.06), whereas the systolic flow displacement at 6 weeks correlated better with aortic diameter at 18 weeks (R = 0.59, P = 0.02). The aortic wall thickness was significantly decreased in the anterior aortic section in banded, compared with sham-operated, pigs (1.5 ± 0.4 vs 2.0 ± 0.1 mm, respectively; P = 0.03). In addition, banded pigs showed a higher degree of cystic medial necrosis and elastin fibre fragmentation, compared with sham-operated animals.
  
  
  CONCLUSIONS
  In this preclinical model of supravalvular aortic stenosis and eccentric flow, we found that systolic flow displacement at earlier stages is positively correlated with the degree of aortic dilatation during follow-up as assessed by three-dimensional phase-contrast magnetic resonance imaging. If our findings are confirmed in further studies, this imaging parameter might be useful to identify those subjects with aortic valve disease who are at risk of developing aortic dilatation at a later stage.
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain.|Cardiovascular Institute, Hospital Clínico San Carlos, Madrid, Spain.
authors.forename: Ali
authors.initials: A
authors.lastname: Ayaon-Albarran
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain.|Cardiovascular Institute, Hospital Clínico San Carlos, Madrid, Spain.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Fernandez-Jimenez
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain.|Hospital Central de Asturias, Oviedo, Spain.
authors.forename: Jacobo
authors.initials: J
authors.lastname: Silva-Guisasola
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain.
authors.forename: Jaume
authors.initials: J
authors.lastname: Agüero
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain.|Philips Healthcare, Madrid, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Sanchez-Gonzalez
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Galan-Arriola
authors.affiliation: Cardiovascular Institute, Hospital Clínico San Carlos, Madrid, Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Reguillo-Lacruz
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain.|Cardiovascular Institute, Hospital Clínico San Carlos, Madrid, Spain.
authors.forename: Luis C
authors.initials: LC
authors.lastname: Maroto Castellanos
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain bibanez@cnic.es.|IIS-Fundación Jiménez Díaz, Madrid, Spain.
authors.forename: Borja
authors.initials: B
authors.lastname: Ibanez
mesh_terms: D000818:Animals; D001014:Aortic Aneurysm / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery; D021921:Aortic Stenosis, Supravalvular / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery; D004195:Disease Models, Animal; D006321:Heart / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D012212:Rheology; D013552:Swine; D016277:Ventricular Function, Left / Q000502:physiology
keywords: 3D magnetic resonance imaging; Animal model; Aortic dilatation; Aortic valve disease; Flow displacement; Thoracic aneurysm