Ambulatory Arterial Stiffness Index Is Increased in Hypertensive Childhood Disease

Abstract

Arterial hypertension in adults is often associated with an increased arterial stiffness, which correlates with the ambulatory arterial stiffness index (AASI) as derived from ambulatory blood pressure (BP) measurements. The purpose of this study was to demonstrate whether children with diagnosed hypertension have an increased AASI as in hypertensive adults. AASI was calculated from 185 ambulatory BP measurements of 114 hypertensive and 71 normotensive, healthy children. Hypertensive children had higher AASI values compared with their normotensive healthy counterparts (0.370 Ϯ 0.120 versus 0.204 Ϯ 0.199, p Ͻ 0.0001). Children with longer duration of hypertension or a history of primary or secondary aortic coarctation displayed even more elevated AASI values. A receiver operator curve derived cut-off of AASI set at 0.301 distinguished (p Ͻ 0.0001) hypertensive from normotensive children with an odds ratio of 8.2, a sensitivity of 81%, and a specificity of 65%. Moreover, AASI correlated with pulse and systolic BP. In conclusion, AASI is elevated in hypertensive children and correlates with the duration and the origin of hypertension in childhood. D iseases linked to arterial hypertension are associated with a significant increased cardiovascular risk, either due to the primary disease (i.e. chronic kidney disease, obesity), or due to the effects of arterial hypertension on the cardiovascular system by consecutively damaging target organs such as the heart, the kidneys, and the brain (1). Increased left ventricular cardiac mass is an established marker of cardiovascular target organ involvement, but is only present in approximately 40% of children with hypertensive diseases (2). Additional and more sensitive noninvasive markers of hypertensive target organ damage are required to determine outcomes and to guide clinical and pharmacological management of childhood hypertension (3). Arterial stiffness, which is a strong predictor of cardiovascular complications and target organ damage in both the general population and patients with hypertensive diseases, would qualify as such a marker (4 -7).Most methods to measure arterial stiffness require special and expensive equipment and trained observers, often not available in clinical practice in a pediatric unit. A novel method to address arterial stiffness based on 24-h ambulatory blood pressure monitoring (ABPM) has been proposed (8): the ambulatory arterial stiffness index (AASI), defined as one minus the regression slope of diastolic over systolic blood pressure (BP) measurements obtained during a 24-h period. This ABPM-derived index has been shown to correlate with classical measures of arterial stiffness, such as pulse wave velocity (9), and to provide prognostic information on cardiovascular mortality and target organ damage throughout a wide age range, including young individuals (10 -12).The purpose of this study was to demonstrate whether AASI is increased in children with various hypertensive diseases, as in hypertensive adults (9 -11). MATERIALS AND MET...

The ambulatory arterial stiffness index is not affected by night-time blood pressure characteristics

“…The 84 hypertensive adults (mean age 32±4.5 years, 33 (39.3%) women) had significantly higher BMI (27.0 ± 6.9 vs 22.5 ± 2.1 kg m À2 , P ¼ 0.0003) and mean 24 h BP (136.5±5.4/87.3±10.5 vs 111.5±6.9/ 73.8 ± 6.4 mm Hg, Po0.0001) compared to the 56 normotensive adults (mean age 27.1 ± 5.8 years, 28 (50%) women). 7 The children with various hypertensive diseases had higher daytime AASI values than those with normotension (0.43 ± 0.15 vs 0.31 ± 0.24, P ¼ 0.0025). Likewise, hypertensive adults showed higher daytime AASI levels than their normotensive counterparts (0.37 ± 0.08 vs 0.24 ± 0.17, Po0.0001; Figure 1).…”

“…These results duplicate the corresponding parameters assessed by using the 24 h AASI. 7 The daytime AASI positively correlated with the 24 h AASI, showing a strong correlation coefficient in both the children and adults (r 2 ¼ 0.70, Po0.0001 and r 2 ¼ 0.71, Po0.0001, in children and in adults respectively). The daytime AASI was even higher when compared to the 24 h AASI within the BP groups (Po0.0001 for the paediatric groups and the normotensive adults and P ¼ 0.02 for the hypertensive adult group).…”

“…5,6 Recently, we demonstrated that AASI, already established in adults, is also elevated in children with hypertensive diseases. 7 Thus, we wanted to assess the extent to which night-time dipping and ambulatory BP monitoring protocols influence the AASI values in both age groups, hypothesizing that daytime AASI, derived by excluding the night-time BP readings, would remain elevated in hypertensive patients.…”

“…All 185 children (114 hypertensive and 71 normotensive) and 141 adults (84 hypertensive and 57 normotensive) from the previous publication 7 were evaluated in the present analysis. The ambulatory BP measurement and the calculation of AASI have previously been described.…”

“…The ambulatory BP measurement and the calculation of AASI have previously been described. 7,8 The night-time BP measurements were excluded after reviewing the patients' protocols indicating bedtime and wake-up time. Data are expressed as mean ± s.d.…”