Pulse waveform analysis of arterial compliance: Relation to other techniques, age, and metabolic variables

To assess the physiologic and clinical relevance of newer noninvasive measu res of vascular compliance, computerized arterial pulse waveform analysis ( CAPWA) of the radial pulse was used to calculate two components of complian ce, C1 (capacitive) and C2 (oscillatory or reflective), in 87 normotensive (NlBP, n = 20), untreated hypertensive (HiBP, n = 21), and treated hyperten sive (HiBP-Rx, n = 46) subjects. These values were compared with two other indices of compliance, the ratio of stroke volume to pulse pressure (SV/PP) and magnetic resonance imaging (MRI)-based aortic distensibility; and were also correlated with demographic and biochemical values. The HiBP subjects displayed lower C1 (1.34 +/- 0.09 v 1.70 +/- 0.11 mL/mm H g, significance [sig] r= .05) and C2 (0.031 +/- 0.003 v 0.073 +/- 0.02 mL/m m Hg, sig =.005) than NlBP subjects. This was not true for C1 (1.64 +/- 0.0 8 mL/mm Hg) and C2 (0.052 =/- 0.005 mL/mm Hg) values in HiBP-Rx subjects. T he C1 (r = 0.917, P <.0001) and C2 (r = 0.677, P <.0001) were both closely related to SV/PP, whereas C1 (r = 0.748, P =.002), but not C2, was signific antly related to MRI-determined aortic distensibility. Among other factors measured, age exerted a strong negative influence on bo th C1 (r = -0.696, P <.0001) and C2 (r = -0.611, P <.0001) compliance compo nents. Positive correlations were observed between C1 (r = 0.863, P =.006), aortic distensibility (r = 0.597, P =.19) and 24-h urinary sodium excretio n, and between CI; and MR spectroscopy-determined in situ skeletal muscle i ntracellular free magnesium (r = 0.827, P =.006), whereas C2 was inversely related to MRT-determined abdominal visceral fat area (r = -0.512 P =.042) and fasting blood glucose (r = -0.846, P =.001). Altogether, the close correspondence between CAPWA, other compliance techni ques, and known cardiovascular risk factors suggests the clinical relevance of CAPWA in the assessment of altered vascular function in hypertension. A m J Hypertens 2000;13:1243-1249 (C) 2000 American Journal of Hypertension, Ltd.