Aortic Pulse Wave Velocity as a Surrogate Marker for Arterial Stiffness and its Determinants in Early Childhood

Background Aortic pulse wave velocity (PWV) has emerged as an established marker for arterial stiffness in order to stratify cardiovascular risk and to improve the prediction of future events in adults. A considerable literature has grown up around hemodynamic indices detecting target organ damage in different pediatric diseases, such as early atherosclerosis, obesity, hypertension or congenital heart diseases. Due to the lack of hard end points there is increasing need for noninvasive surrogate markers to identify altered vascular function in pediatric populations. However, particularly for preschool children data on PWV are sparse. Therefore, this study was set out to characterize factors determining PWV in early childhood. Methods The present data is based on the baseline measurements from the Fitness for Kids Study, a cluster randomized controlled exercise intervention program in preschoolers. A total of 139 healthy children aged 2 to 6 years (4.80 ± 0.82 years, 51.8 % girls) were recruited from five daycare centers in Hamburg, Germany. We measured weight, height, heart rate, blood pressure (BP), mean arterial BP (MAP) as well as PWV noninvasively by a validated oscillometric device (Mobil-O-Graph, I.E.M., Stolberg, Germany). Statistical analyses included correlations to examine the relation between anthropometrics, hemodynamics and PWV, as well as linear mixed models with random intercepts for daycare centers to assess sex differences and to derive the determinants of PWV. Results On average, boys had a PWV of 4.34 ± 0.32 m/s and girls of 4.29 ± 0.32 m/s (P = 0.324). Correlation analysis revealed significant associations of PWV with height, weight, BMI, systolic and diastolic BP as well as MAP (P<0.05), but not with age. In the multivariate analysis we found that MAP (beta = 0.037, P<0.001) was the major determinant of PWV in the investigated age range. Additionally, mean standardized values of systolic BP and MAP increased with age and height, while PWV weakly inclined or remained practically unchanged. Conclusion The study offers important insights into arterial ageing in early life, namely that not age, but rather MAP independently predicts PWV in very young children. According to previous research MAP physiologically increases with growth, which in turn enhances elastic properties and compliance of arteries despite an accompanying age and BP-dependent rise in arterial stiffening. This effect on vascular structure and function might explain our finding that PWV remained constant and will probably start to show a noticeable increase with onset of puberty. Our results emphasize the usefulness not only of routine BP measurements in early childhood but moreover of measuring PWV in order to evaluate arterial function. Research questions should focus on further clinical and lifestyle risk factors potentially influencing PWV in healthy young children.