Age-Related Changes in Total Arterial Capacitance From Birth to Maturity in a Normotensive Population

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Abstract
We evaluated the effect of body growth and aging on the ratio of echocardiographic (Teichholz) stroke volume to pulse pressure (SV/PP ratio) in 373 normal-weight, normotensive children to adolescents (1 day to 17 years old; 166 girls, 87 nonwhite) and 393 normal adults (17 to 85 years old; 164 women, 112 nonwhite). Stroke volume increased with age in children ( r =.64, P <.0001) and was stable in adults; pulse pressure decreased slightly with age in children ( r =−.10, P =.06) and increased in adults ( r =.29, P <.0001). As a consequence, SV/PP ratio increased with age in children ( r =.51, P <.0001) and decreased in adults ( r =−.18, P =.0004). To control for changes in body size that influence the size of the arterial tree, we used ANCOVA to adjust SV/PP for body size. Body size–adjusted SV/PP ratio was no longer related to age in children, whereas the negative relation with aging in adults remained statistically significant ( r =−.19, P <.0002). Heart rate was negatively related to SV/PP ratio in both children and adolescents and adults, but this relation did not influence the relation with age. In multivariate analysis, high SV/PP ratio was predicted by greater height ( P <.002) and weight ( P <.04) and nonwhite race ( P <.001) in children and adolescents and by younger age ( P <.0001), greater weight ( P <.0001), and low heart rate ( P <.001) in adults. Sex did not enter the regression models. Thus, (1) SV/PP ratio is a measure of increasing capacity of the arterial tree during growth, whereas it depends on arterial compliance during adulthood through old age; (2) arterial compliance decreases progressively with aging; (3) the apparent difference between males and females might be due to their different body sizes.