Vasa vasorum growth in the coronary arteries of newborn pigs.

Experimental studies have shown that a "plexus" of vasa vasorum already exists in fetal arteries. In this study we examine the further development of vasa vasorum in the newborn. Hearts from 1- and 6-month-old pigs were harvested and infused with Microfil via the aortic ostia of the coronary arteries at physiological pressure (100 mmHg). Coronary arteries (RCA, LAD, and LCX) were then isolated and scanned intact with micro-CT (20 microm cubic voxel size). Using Analyze 5.0 software we digitally isolated individual vasa vasorum trees (eight from 1-month-old and eight from 6-month-old pigs) and measured geometrical data such as interbranch segmental diameters, lengths, and branching angles as well as mother-daughter branch relationships for all segments of each vasa vasorum tree structure. Also, we determined the volume of vessel wall perfused by individual vasa vasorum trees. Our results show that the vasa vasorum architecture in newborn pigs is already tree-like, and this structure as well as the volume of vessel wall perfused by it expand in concert with the growth of the host coronary artery. We give quantitative details of this growth of vasa vasorum in terms of its branching architecture and hemodynamic capacity, based on direct measurements from 3D images of this microvasculature.