Branching properties of the pulmonary arterial tree during pre- and postnatal development

We measured arterial diameter as a function of generation number (#) in the arteriograms of six postmortem lung preparations from human infants aged 35 to 48 wks post-conceptional age (PCA). The log-log plot of mean diameter as a function of generation number revealed a linear decrease in mean and median diameter with increasing #, which was characterized by its slope alpha and intercept beta (linear regression). The mean arterial diameter per generation as well as the ratio (F) between mother and larger daughter branch and the relative ratio of asymmetry (A) between the larger and the smaller daughter branch was calculated. The values of F(#) and A(#) were found to be constant between 2 and 15 generations in individual lungs which is consistent with the pulmonary arterial tree exhibiting fractal properties. The averaged values ((f) over bar and (A) over bar within a subject) of F(#) and A(#) as well as alpha and beta were determined for each lung preparation and found to be constant from 35 to 48 weeks of age, revealing unchanged branching properties in the pre- and postnatal phase of human lung development. (C) 2003 Elsevier B.V. All rights reserved.