Histological and histochemical studies on arteries of young Koreans
Arteriosclerosis of young persons has been reported with increasing frequency in recent years. Considering the enormous volume of literature devoted to the coronary arteries and aortas, the dearth of attention given to these vessels in newborns, infants and children is rather surprising. the most comprehensive study of juvenile arteriosclerosis is that of Zeek who reviewed the world literature up to 1930. She collected 98 necropsied cases of patients under 20 years of age, and found that one
half of the total number of the cases occured during the age period from 10 to 14 years, with 6 cases less than one year old and 10 cases between one and 4 years of age. Willius and Smith (1933) studied the incidence and degree of coronary and aortic sclerosis in 5060 consecutive post-mortem examinations. They found that in the age group from 0 to 9 years of age the coronary arteries revealed a garde on sclerosis in 10.2 percent, and a grade 2 sclerosis in 0.2 percent. Similarly in the same age group the aorta showed a grade one in 23.2 percent, a grade 2 in 0.5
percent, and a grade 3 in 0.2 percent. Enos, Holmes, and Beyer(1953) examined the coronary arteries of 300 cases of United States soldiers, whose ages ranged from 18 to 48 years, killed in action in Korea, and found that some gross evidence of coronary disease varying from fibrous thickening to complete occlusion of the coronary arteries was demonstrated in 77.3 percent. The fact that juvenile arteriosclerosis, even in the abscence of metabolic disorders such as diabetes mellitus and xanthomatosis, may be progressively fatal, is attested to by French and Dock's analysis of 80 fatal cases of coronary arteriosclerosis in soldiers ranging from 20 to 36 years of age(1944).
Some earlier investigators have included intimal changes of coronary arteries or aortas of young people in their over all survey of age changes occuring in these vessels, but the significance of these intimal changes was not entirely clear. Some claimed that these changes were physiologic, and some believed that they were secondary changes due to acute infections or toxic substances. Recently, however Dock (1946), Fangman and Hellwig (1947), and Wilens (1951) investigated the arterial changes of young people and their significance as to the development of arteriosclerosis and they considered these changes as important precursors of arteriosclerosis. Prior and Jones (1952) postulated that the intimal thickening found in some of the aortas of infants and children might represent the earliest
phase in the development of adult arteriosclerosis. Moon (1957) studied the coronary arteries of 105 young individuals ranging from fetuses to young adults and found that the arterial changes frequently present in infants were identical with the early nonlipid phases of arteriosclerosis in adults.
Recent investigations with many improved techniques, especially histochemical methods, also added much valuable light on our knowledge of the histogenesis of arteriosclerosis. The long known role of the lipid accumulation in the development of arteriosclerosis became disputed, and the importance of elastic degeneration and accumulation of mucopolysaccharide have been emphasized (Moon and Rinehart, 1952; Taylor, 1953; Moon, 1957; Adams and Tuqan, 1961; Curran and Crane, 1962). It is generally understood that the incidence of arteriosclerosis, particularly
that of myocardial infarction among Koreans is much lower than that of Caucasians. However our observations on the arterial alterations in Koreans are extremely limited. Kim (1961) studied some of the gross findings of arteriosclerosis of the aortas in Koreans. Shin (1963) of our department reported histochemical studies of fetal arteries of Koreans. The present paper is to report the histological and histochemical findings in various age groups of 207 Koreans and to study various arteries for the histogenesis of arteriosclerosis.
Materials and Methods
Two hundred and seven cases, from both sexes up to 30 years of age, were collected from the autopsy cases of the Wonju Union Christian Hospital, Seoul City Children's Hospital, and the National Medical Center. After gross examination, the sections were taken from the coronary arteries, ascending and descending aortas and renal arteries. These were stained with hematoxylin and eosin stain, Verhoeff's elastic stain and colloidal iron stain. The frozen sections were stained with oil red 0 stain.
The intimal thickening was shown as a percentage of the estimated thickness of the intima compared to that of the entire arterial wall. The degrees of other histological and histochemical findings were graded into mild, moderate and sever
changes. The specimens were divided into ten groups according to age and the number from each group is as follows:
Group Ⅰ. Less than one month of age………………………16 cases
Group Ⅱ. 1-2 months of age………………………………… 22 cases
Group Ⅲ. 2-4 months of age………………………………… 29 cases
Group Ⅳ. 4-12 months of age…………………………………32 cases
Group Ⅴ. 1-5 years of age……………………………………48 cases
Group Ⅵ. 5-10 years of age………………………………… 12 cases
Group Ⅶ. 10-15 years of age…………………………………10 cases
Group Ⅷ. 15-20 years of age…………………………………15 cases
Group Ⅸ. 20-25 years of age…………………………………10 cases
Group Ⅹ. 25-30 years of age…………………………………13 cases
Arterial alterationscharacterized by nearly simultaneous occurrence of intimal thickening, fraying and fragmentation of internal elastic membrane, accumulation of mucopolysaccharide and less frequently regeneration of internal elastic membrane and deposition of lipid were frequently found in coronary arteries and aortas, and only rarely in renal arteries. These sclerotic changes were identical with the early nonlipid phase of arteriosclerosis in adults. These sclerotic changes were present in 75.5 percent of the coronary arteries, 72.5 percent of the ascending aortas, 83.1 percent of the descending aortas and 7.4 percent of the renal arteries.
These sclerotic changes were frequently present in coronary arteries and aortas even in infants less than one month of age, and the incidence of these findings increased with age. In coronary arteries, the incidence of these changes was 31.2 percent in infants less than one month, 47.6 percent in infants of one to two months, and this increased gradually after three months and reached up to 100 percent at 16 years of age. Likewise in ascending aortas this incidence was 50 percent in group Ⅰ, 77.3 percent in group Ⅱ, and beyond this it increased gradually and reached up to 100 percent after 25 years of age. In the descending aorta it was 58.3 percent in group Ⅰ, 78.9 percent in group Ⅱ, and increased gradually thereafter, and reached up to 100 percent from group Ⅶ.
Intimal thcikening was most pronounced in the coronary arteries, where it's progression with age was also most pronounced. The thickness of the intima of coronary arteries was 15 percent in group Ⅰ, 24 percent in group Ⅱ, 34 percent in
group Ⅳ. Progressive thickening was noted in infants less than one year of age and this became less pronounced between 1 year and 15 years of age, and the thickening reached up to 50 percent at 16 years of age. Intimal thickening was much less pronounced in aorta, and it was a little greater in the descending aorta than in the ascending aorta.
Elastic degeneration and accumulation of mucopolysaccharide were noted in areas of intimal thickening and the severity of these changes generally paralleled with that of the intimal thickening. Elastic degeneration was present occasionally
without intimal thickening. There was no correlation between deposition of lipid and intimal thickening. Deposition of lipid was rather rare in the newborn period, but thereafter was found in about half of the cases. These observations indicate that deposition of lipid is not an initating factor in the development of arterlosclerosis, but elastic degeneration and accumulation of mucopolysaccharide play an important role.
The frequent observation of deposition of lipid in both coronary artery and aorta, if it occurs, suggests and individual factor in the deposition of lipid. Medial degeneration of the aorta characterized by fragmentation and loss of elastic tissue along with an associated accumulation of mucopolysaccharide was
frequently present. It was found in about half of the newborns and it's incidence increased after 5 years of age.