Digital pulse contour analysis: investigating age-dependent indices of arterial compliance

The resting peripheral volume pulse wave of 44 subjects within three age categories (30-39, 40-49, 50) has been characterized using a novel algorithm for the automated determination of a mean pulse function. The contour of this resting mean pulse has been analyzed with regard to its systolic and diastolic characteristics. Previously described indices of arterial stiffness and viscoelasticity have been investigated for age-dependent variations associated with arterial mechanical properties. Measures of the minimum rise time (MRT) and the stiffness index (SI) demonstrated strong correlations with age and each other, although their derivations are unrelated. While significant correlations existed (|r| = 0.50-0.78, p < or = 0.002), pairwise comparisons between the right and left hands did not demonstrate significant differences for the minimum rise time parameter; however, the stiffness index was significantly lower in the left hand versus the right (p = 0.009). With regard to age, the youngest age group had significantly lower MRT and SI values than the two older groups. For these data, this was only demonstrated in parameters calculated for the right hand because of higher variability within age groups for the left hand. A normalized average mean pulse for each age group was determined which visually illustrated the contour changes associated with the MRT and SI parameters that occur in both the systolic and diastolic portions of the pulse. The finding that differences between the age groups were significantly more evident for the right hand suggests that the physical site for such testing may be an important consideration. This study provides further evidence regarding the merit of using contour analysis when assessing the peripheral volume pulse and the importance of establishing ageing indices for such analysis.