P.024 Measuring Local Pulse Wave Velocity Using Non-Invasive Multiple M-Line Ultrasound

Abstract

Introduction

Local pulse wave velocity (PWV) provides direct information about the mechanical properties of an artery. Although PWV is related to arterial stiffness and both are predictors of cardiovascular events, no methods are currently available to measure local PWV non-invasively.

Method

The common carotid artery (CCA) of 4 young subjects were measured with multiple M-line ultrasound, resulting in 14 distension waveforms spaced over 17 mm. PWV was determined by applying linear regression to the foot of the distension waveforms and the corresponding echo line position. The PWV was accepted for further analysis if the correlation coefficient of both parameters was above 0.95.

Results

The local PWV measurement method had a good intra-subject coefficient of variation (CV) of <5%. The average PWV was 3.5±0.7 m/s with an inter-subject CV of 20%. One subject, with high blood pressure (140/90 mmHg), had a PWV of 4.6±0.2 m/s.

Discussion

These results show a low PWV in the CCA compared to conventional carotid-femoral (CF) PWV. The muscular arteries that are part of the CF–trajectory increase the CF-PWV. Moreover since pulse waves travel in opposite direction, using the distance between carotid and femoral artery causes CF-PWV to overestimate true PWV.

Conclusion

Local PWV can be measured with good precision using multiple M-line ultrasound. The inter-subject variation (CV = 20%) exceeds the intra-subject variation (CV = 5%), enabling distinction between individual differences. More measurements are required to evaluate the accuracy of the local PWV method in vivo.