[Left-ventricular surface trabeculae of the interventricular septum in the human fetal heart]

Left-ventricular surface of the interventricular septum (IVS) was studied in the heart of 85 human fetuses (at weeks 17-28 of development) formed without congenital defects and minor abnormalities. Two anatomical types of trabeculae (bridge-like and parietal) and their two topographical groups are described: trabeculae of the anterior corner of the left ventricle (LV) and the septal trabeculae. The prevalence of trabeculae in both groups was found to be equal (81-81.2%). No correlation between the numbers of septal trabeculae and the trabeculae of the anterior LV corner was found. While the parietal trabeculae were detected in both groups, the bridge-like type was found only in the anterior LV corner. The number of the bridge-like trabeculae of the anterior LV corner and the septal trabeculae increased from the base to the apex of the heart; this was accompanied by the decrease in the IVS myocardium compactness. Among the first topographical group, there were trabeculae in the shape of skewed cylinders or truncated cones, flattened perpendicularly to their long axis. As a rule, in cone-shaped trabeculae, their broad base was directed towards the IVS. In the second group, the ribbon-shaped trabeculae were prevalent. The data on trabecular width are presented. The formation of the cardiac LV and IVS trabecular pattern in prenatal period is discussed.