title: Geometry and fusion of aortic valves from pulsatile flow ventricular assist device patients.
abstract: OBJECTIVE
  Aortic valve commissural fusion is a process in which fibrous tissue is deposited at the aortic valve commissures, creating adhesion between leaflets and preventing opening. Fusion has recently been associated with the implantation of left ventricular assist devices (VADs), affecting upwards of 50% of patients in recent studies. Aortic incompetence has also been associated with pulsatile VAD use, but a specific structural mechanism has not been identified. The study aim was to measure aortic valve geometry and fusion in tissue samples from explanted hearts of VAD recipients and to identify features that might explain the development of aortic valve dysfunction.
  
  
  METHODS
  The diameter, perimeter and thickness of the aortic root, as well as the height, edge length and thickness of each of the three aortic leaflets were measured in seven valves. Histological studies were performed of both fused and unfused leaflets.
  
  
  RESULTS
  The aortic root geometry showed an elliptical aorta, with asymmetric leaflets. The right coronary leaflet had the greatest edge length, but was thinnest. The other two leaflets were smaller, but slightly thicker. Overall, the aorta and valve geometry was within the normal range. Fusion was found in five of the seven valves studied, and often observed in multiple leaflets. Fusion length correlated loosely with the time of VAD support. Tissue from both fused and unfused valves showed unilateral fibrosis in the leaflets, and a loss of the laminar tissue structure that was related to the duration of VAD support.
  
  
  CONCLUSIONS
  These findings support previous observations that pathological changes occur in the aortic valves of VAD patients shortly after implantation. While the tissue exhibits abnormalities in the structure, the geometry does not show gross remodeling such as annular dilatation or leaflet lengthening that might precede the development of aortic valve dysfunction. These changes are associated with the development of aortic valve fusion, and may be related to the biomechanical changes introduced by the VAD.
authors.affiliation: Bioengineering Program, Mail Code 1323, San Diego State University, San Diego, CA 92182-1323, USA. kmn@kahuna.sdsu.edu
authors.forename: Karen
authors.initials: K
authors.lastname: May-Newman
authors.forename: Annamarie
authors.initials: A
authors.lastname: Mendoza
authors.forename: Dina J K
authors.initials: DJ
authors.lastname: Abulon
authors.forename: Mrunalini
authors.initials: M
authors.lastname: Joshi
authors.forename: Anand
authors.initials: A
authors.lastname: Kunda
authors.forename: Walter
authors.initials: W
authors.lastname: Dembitsky
mesh_terms: D000328:Adult; D000368:Aged; D001021:Aortic Valve / Q000473:pathology* / Q000503:physiopathology; D001696:Biomechanical Phenomena; D002140:California; D005260:Female; D005355:Fibrosis; D006349:Heart Valve Diseases / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D006353:Heart-Assist Devices; D006801:Humans; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D011673:Pulsatile Flow; D013997:Time Factors