Coronary arteries in children up to the age of ten years II. Intimal thickening and its role in atherosclerotic involvement.

The frequency, histologic feature and topographic distribution of the first foci of intimal thickening were investigated in the coronary arteries of 40 fetuses, 40 neonates and 90 children up to the age of ten years. Particular hemodynamic and mechanical stresses seem to be involved in the precocious development of these isolated foci of intimal thickening which appeared in the early fetal life as well as in their progressive extension and fusion which give rise to diffuse thickened intima. After birth the stressed areas with thickened intima might evolve toward fibrosis and the "protected" ones toward degenerative and necrotic processes. These processes were detected in approximately 8% of the 5-10 year-old children and appeared before the development of fatty streaks or other forms of lipid accumulation.