Key result
TDI shows pre-ejection spikes end ~10 ms after mitral valve closure, indicating non-isovolumic electromechanical activation.
Why the study?
Pre- and post-ejection tissue Doppler velocity spikes were assumed to represent isovolumic contraction and relaxation movements, but this was not in accordance with newer studies.
Observational (n=22)
Tissue Doppler velocity spikes during pre- and post-ejection are not isovolumic events, but rather relate to electromechanical activation and valve closure mechanisms.
Background Tissue Doppler shows short duration velocity spikes during pre‐ and post‐ejection (protodiastole). They have been assumed to be isovolumic contraction and relaxation movements, but this is not in accordance with newer studies. Methods We examined 22 healthy volunteers. Valve closures and openings were determined from spectral Doppler from LVOT and mitral inflow and transferred to colour tissue Doppler recordings for comparison with tissue velocities, colour M‐mode and strain rate (SR). Results Pre‐ejection positive velocity spikes were simultaneous in both walls, starting ca. 24.8 ± 10.1 ms after start QRS, duration 51.5 ± 10.8 ms, ending 10.2 ± 11.5 ms after mitral valve closure (MVC) ( p < 0.001). There were corresponding colour tracings and negative strain rate. Protodiastolic lengthening was predominant in the septum. Negative velocity spikes had a duration of 35.5 ± 10.7 ms, ending 9.5 ± 14.7 ms after aortic valve closure (AVC, p < 0.001) in septum. During isovolumic relaxation, strain rate showed apical lengthening (Peak SR—0.72 ± 0.50 s −1 ) and basal shortening (Peak SR 0.44 ± 0.63 s −1 ). Conclusion Electromechanical activation of the LV is simultaneous in septum and lateral wall, occurs before MVC, is terminated by MVC itself and is thus not isovolumic. Protodiastole is a short event of lengthening, predominantly in the septum. It may be the mechanism for valve closure and ends by AVC itself. Isovolumic relaxation occurs after this velocity spike, and is characterized by elongation of the apex, shortening of the base, thus showing a volume shift from base towards apex.
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Støylen et al. (2021) conducted an observational in Healthy volunteers (n=22). Tissue Doppler imaging was evaluated on Timing of pre-ejection positive velocity spikes relative to mitral valve closure (p=<0.001). Tissue Doppler imaging showed pre-ejection velocity spikes ended 10.2 ± 11.5 ms after mitral valve closure (p<0.001), indicating electromechanical activation is not isovolumic.
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