Assessment of arterial stiffness using applanation tonometry

Augmentation index (AIx) and pulse wave velocity (PWV) assess functional and structural aspects of the vascular wall and are independent markers of cardiovascular morbidity and mortality. Like blood pressure, many factors, genetic, structural, and physiological, affect AIx and PWV. AIx and PWV can be assessed noninvasively using applanation tonometry. The technique is simple, but comes with a number of practical and technical limitations that have not been well documented and (or) explored. This review considers pulse wave analysis in the context of cardiovascular disease, and considers its limitations. Data are presented indicating that the placement of the probe is critical, and that the amplitude of the obtained signal is related to the variability in measurements. On a more theoretical note, issues are discussed regarding the applied transfer functions that are built in the devices to assess central AIx from peripheral waveforms. Altogether, PWV and its analysis are useful additions to the arsenal of parameters that can be used to assess vascular health and to estimate vascular risk. Yet, our analysis underscores the necessity for precise operating procedures, and calls for transparency regarding the applied transfer functions of commercial devices.