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. 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. 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.
