Study of coronary intimal thickening.

A light microscopic study on intimal thickening carried out on 932 subjects 1-50 years old and on 22 selected topographic sites of the coronary arterial bed, revealed: (a) In similar topographic sites intimal thickening developed 5-15 years earlier in subjects with than in subjects without minor deviations from the common type of distribution of the coronary arteries. (b) The most rapid development of the intimal layer was detected in children aged 11-15 years. (c) 6% of children who died of acute diseases (mainly acute peritonitis) showed intimal thickening in both major coronary arteries and branch vessels; in children who died of accidents thickening developed only in the major coronary arteries. (d) More than 50% of subjects 46-50 years old (considered to be in the preclinical stage of ischemic heart disease) exhibited intimal thickening in the branch vessels usually non-opened during routine autopsy and non-removed for light-microscopic examination. (e) An intima/media ratio between 2.0 and 3.0 was associated with a 50% reduction in the luminal diameter; this reduction increased up to 75% when the intima/media ratio surpassed 3.0, the very thick intima acquiring the feature of a 'fixed stenotic lesion' in spite of its apparent normal aspect on light-microscopic examination.