Background In normal subjects, systolic longitudinal regional velocity profiles (SVP) (measured both based on Pulsed or Tissue Doppler) have a non-uniform pattern. SVP from the right ventricle (RV), the septal (Sep) and the inferior wall are similar in shape and tend to be mono-phasic. Their shape differs markedly from the lateral (LW), the posterior and the anterior wall, which are bi-phasic. We studied the hypothesis that the double peaked SVP in the left ventricular free walls are caused by inter-ventricular interaction. This might have additional implication in understanding the measurements of the timing of SVP maxima in pathology, as for example used to determine intra-ventricular dyssynchrony in heart failure.
Methods and Results 38 healthy individuals underwent a standard echo examination and a tissue Doppler study. SVP from the RV, Sep and LW basal segments were acquired in an apical 4-chamber view. The amplitude and timing of the peak velocities were measured. If a double peak was present, the amplitude and timing of the dip was calculated.<BR> RV and Sep had a single systolic velocity peak, while the LW had two peaks with a clear dip between both peaks. The first peak in the LW was the earliest event in the cycle (119±19ms) followed by the peak Sep (123±20ms; p=0.34). Peak RV velocity occurred at the same time as the dip in the LW (200±30 vs 203±30ms respectively; p=0.53).
Conclusions Our study suggests that the bi-phasic SVP in the free walls are likely caused by inter-ventricular interaction. Therefore the use of timing of maxima on SVP should be used with great caution when looking for intra-ventricular dyssynchrony as the peaks are influenced by RV function.
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