AORTIC PULSE WAVE VELOCITY MEASURED BY PULSE WAVE IMAGING (PWI): A COMPARISON WITH APPLANATION TONOMETRY

Arterial stiffness is a well-established indicator of cardiovascular disease outcome. Pulse Wave Velocity (PWV) is a surrogate for arterial stiffness that is measured either globally using carotid to femoral applanation tonometry or locally using biomedical imaging methods. Pulse Wave Imaging (PWI) is an ultrasound-based method for both qualitative visualisation of pulse wave propagation and quantitative estimation of arterial stiffness. The objective of this study is to assess the PWI performance in PWV estimation by comparing local abdominal aortic PWV values obtained by PWI to the carotid-femoral PWV measured by applanation tonometry.

A total of 18 subjects (age 18-66, 32.5±14.5) with no history of cardiovascular disease were consecutively tested by both PWI and tonometry.

The correlation coefficient r between values found by the two methods was found to be equal to 0.68. A linear regression yielded PWV_PWI = 1.02* PWV_tonometry +0.15. Tukey mean-difference plots indicated that PWV_PWI was significantly lower than PWV_tonometry (-0.3 m/s) at lower PWV values (PWV≤7 m/s), whereas PWV_PWI was significantly higher (+1.4 m/s) than PWV_tonometry at higher PWV values (PWV>7 m/s).

Despite the regional nature of the PWV_PWI measurements, as opposed to the global PWV_tonometry measurements, abdominal PWV_PWI and carotid-femoral PWV_tonometry values were found to be similar, with an average bias equal to 0.25 m/s. Such a bias and its variation with PWV may be partially explained by both physiological variations of PWV along the arterial tree and by the increasing uncertainty of the PWV estimate by PWI as PWV increases.