P2 Determination of Local Pulse Wave Velocity does not Affected by Reflection

Abstract

Objective

PWV is an important indicator of arterial stiffness and cardiovascular diseases. Local PWV would provide a more accurate estimation of local stiffness than does regional PWV. Local PWV is commonly determined by loop techniques, such as the PU-loop method and the aim of this study is to examine the effect of reflections on the accuracy of determining local PWV by loop Methods.

Methods

Pressure and flow were measured along a flexible tube that was connected to three positive and three negative reflections. PWV was calculated using the PU-loop method and wave intensity analysis was used to separate the pressure and flow velocity waveforms, using PWV of 20.2 m/s measured determined by the foot-to-foot method. Local reflection coefficient I was calculated as the ratio of magnitudes of backward to forward pressure.

Results

Figure 1 shows local PWV is not affected by the reflection until measurements were taken at 80 cm away from reflection site, when it starts to increase or decrease depending on the type of the reflection. The threshold of R corresponding to the non-affected PWV by reflections is ±0.36 ± 0.05 (mean ± SD).

Conclusions

The results of this study indicate that local PWV determined by PU-loop are only affected by reflections when the local reflection coefficient is greater than ±0.36 ± 0.05, irrespective of the distance to the reflection site. If/given reflections of the current study are comparable to those measured in vivo, PWV would not be affected by reflections in the arterial system.

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