Microvascular development in porcine right and left ventricular walls

Patients with congenital heart disease who have a morphological right ventricle (RV) serving as a systemic ventricle have an increased incidence of RV dysfunction. A different structural response of microvessels to increased pressure load in the RV is a possible mechanism for this dysfunction. To examine the merit of this hypothesis, we explored the possibility that in the normal heart, the branching architecture of microvasculature in walls of the left ventricle (LV) and RV mature differently. The branching structure of intramyocardial arterioles and their downstream branches were investigated using three-dimensional (3D) micro-computed tomography (CT) images in different regions of the RV and LV walls of normal fetal, 1-mo, and 5-mo old pigs. The results point to a significant difference in the volume of myocardium perfused per vessel cross-sectional area (CSA) between the LV and RV walls at 5 mo. We speculate that this difference may be related to the reserve functional capacity of the LV, which requires a corresponding reserve in the expansion capacity of vasculature in the LV wall.