Current assessment of pulse wave velocity: comprehensive review of validation studies.

Objective: Carotid-femoral pulse wave velocity (PWV) is considered the gold standard for arterial stiffness assessment in clinical practice. A large number of devices to measure PWV have been developed and validated. We reviewed different validation studies of PWV estimation techniques and assessed their conformity to the Artery Society Guidelines and the American Heart Association recommendations.

Methods: Pubmed and Medline (1995-2017) were searched to identify PWV validation studies. Of the 96 article retrieved, 26 met the inclusion criteria.

Results: Several devices had been developed and validated to noninvasively measure arterial stiffness, using applanation tonometry (SphygmoCor, PulsePen), piezoelectric mechanotransducers (Complior), cuff-based oscillometry (Arteriograph, Vicorder and Mobil-O-Graph), photodiode sensors (pOpmètre) and devices assessing brachial-ankle pulse wave velocity and cardiac-ankle PWV. Ultrasound technique and MRI remain confined to clinical research. Good agreement was found with the Artery Society Guidelines. Two studies (Complior, SphygmoCor Xcel) showed best adherence with the guidelines. In Arteriograph, MRI, ultrasound and SphygmoCor Xcel validation studies sample size was smaller than the minimum suggested by the guidelines. High discrepancies between devices were shown in distance estimation: in two studies (Arteriograph, Complior) path length was estimated in conformity to the guidelines. Transit time was calculated using the intersecting tangent method, but in two studies (Vicorder, pOpmètre) best agreement was found using the maximum of the second derivative. Six studies reached the accuracy level 'excellent' defined in the Artery guidelines.

Conclusion: Method to assess transit time and path length need validation in larger populations. Further studies are required in different risk population to implement clinical applicability of every device.