Background: Quantitative information about the elastic properties of the large arteries can be obtained by determination of the pressure and the pulsatile changes of arterial diameter.
Objective: To study the stiffness of major branches (common carotid artery; CCA, abdominal aorta; AA and femoral artery; FA) in newborn infants.
Study design: The arterial stiffness index (SI) values were measured with a phase locked loop ultrasound technique to estimate the arterial systolic and diastolic diameters and their correlation with blood pressure.
Subjects: We studied 62 appropriate-for-gestational age infants (between 30 and 41 weeks of gestation at birth) including 33 preterm infants.
Results: The systolic and diastolic diameters of the CCA, AA and FA, as well as the SI, increased with the gestational age at birth. In the SI of the FA, there was considerable variation in the individual values for a given gestational age at birth. The gestational age associated increase in stiffness was statistically significant only in the CCA and the AA. Although the mechanical properties of the FA were significantly influenced by physical activities during the active waking and quiet sleeping states, the calculated SI values were less vulnerable to these activities in the central arteries.
Conclusion: These results indicate that the SI of the FA (peripheral muscular artery) is modified appreciably by vasoactive stimuli. The mechanical properties of the deeper elastic arteries in newborn infants provide sufficiently reliable information about changes caused by development.