title: Aortic valve closure: relation to tissue velocities by Doppler and speckle tracking in normal subjects.
abstract: OBJECTIVE
  The aim of this study is to resolve what event in velocity/time curves represents aortic valve closure (AVC) by comparing the timing of AVC visually seen in high frame rate B-mode images with simultaneously recorded apical tissue Doppler imaging (TDI) and speckle-tracking-based velocity/time curves from normal subjects.
  
  
  RESULTS
  A total of 73 recordings from 11 normal subjects were analysed. The acquisition frame rate was equal for both TDI and B-mode (mean 147.5 FPS). The study shows conclusively that the initial negative velocity spike at end-systole occurs before AVC, 26.7 +/- 6.2 ms before reference (P < 0.001). The event closest to the reference was the time point of zero velocity after the negative spike, 2.6 +/- 8.2 ms before reference. These events are related to the reference in the same way for velocity/time curves by speckle tracking, colour M-mode, and pulsed wave tissue Doppler.
  
  
  CONCLUSIONS
  AVC in velocity/time curves should be positioned at the end of the negative spike after ejection. Establishing AVC from the correct event in velocity/time curves will ensure more consistent displacement, velocity, strain, and strain rate parameters.
authors.affiliation: Department of Circulation and Medical Imaging, NTNU, ISB Medisinsk Teknisk Forskningssenter, NO-7489 Trondheim, Norway. sveinaaa@ntnu.no
authors.forename: Svein A
authors.initials: SA
authors.lastname: Aase
authors.forename: Hans
authors.initials: H
authors.lastname: Torp
authors.forename: Asbjørn
authors.initials: A
authors.lastname: Støylen
mesh_terms: D001021:Aortic Valve / Q000000981:diagnostic imaging* / Q000502:physiology; D006801:Humans; D008297:Male; D013997:Time Factors; D014463:Ultrasonography