Comparison Of Three Different Methods To Calculate Aortic Pulse Wave Velocity (Pwv) Using A 1d Model Of The Systemic Circulation

Abstract

The Arteriograph, a device basically consisting of a brachial cuff, has recently been launched as a new tool to measure pulse wave velocity (PWV). Brachial blood pressure is measured during supra-systolic pressure inflation of the cuff, yielding pressure waveforms with pronounced first and secondary peaks. The second peak is ascribed to a reflection from the aortic bifurcation, and PWV is calculated as the ratio of 2 times the jugulum-symphysis distance (~ aortic root – bifurcation) and the time difference between the two peaks (Ts1-s2). To test this working principle, we used a numerical model of the arterial tree to simulate pressure and flow in the normal configuration, and in a configuration with an occluded brachial artery (~supra-systolic over-inflation). A pronounced second peak in the pressure signal was found at the location of the cuff for the occluded configuration. Wave intensity analysis showed that this peak was caused by a forward compression wave, confirming the Arteriograph hypothesis. Simulations with 6 different stiffness values showed a linear correlation between 1/Ts1-s2 and PWV (R²=0.97). It was, however, hard to locate the reflection site which, in combination with the transit time, reproduced the correct PWV. The distance to the aortic bifurcation was 45 cm, whereas the effective length of the simulated arterial tree was 27 ± 3 cm. The distance needed to reproduce PWV from Ts1-s2 was 70 ± 6 cm. In conclusion, although the numerical model supports the basic working principle of the Arteriograph, measurement of actual PWV using the device might be more challenging.