Bg. Halloran et al., LOCALIZATION OF AORTIC DISEASE IS ASSOCIATED WITH INTRINSIC DIFFERENCES IN AORTIC STRUCTURE, The Journal of surgical research, 59(1), 1995, pp. 17-22
Purpose. While localization of atherosclerosis and aneurysms to the in
frarenal aorta has been attributed, in part, to hemodynamic factors, a
natomic differences between the proximal and the distal aorta may also
be important. Our purpose was to determine the changes in content and
organization of major structural proteins (elastin and collagen) thro
ughout the normal human aorta. Methods. Biochemical analysis for desmo
sine-isodesmosine (elastin) and hydroxyproline (collagen) content was
done by HPLC on complete l-cm transverse rings removed from the ascend
ing and descending thoracic aorta and abdominal supraceliac, suprarena
l, and midinfrarenal aorta. Elastin and collagen content was normalize
d to lumenal surface area and compared by ANOVA. Light microscopy and
optical micrometry were used to determine changes in intimal, medial,
and adventitial thickness and number of elastin lamellae at each level
. Results. Both collaqen/cm(2) and elastin/cm(2) decrease from the pro
ximal to distal aorta, Collagen content did not differ among the three
abdominal segments, but there was a 58% decrease in elastin between t
he suprarenal and the infrarenal aorta. The proportion of elastin and
collagen does not differ throughout the aorta except in the infrarenal
aorta where there is decreased elastin relative to collagen. Conclusi
on. Collagen and elastin in the distal aorta bear an increased load as
compared to the proximal aorta. The infrarenal aorta differs biochemi
cally and histologically from the remainder of the aorta. A decrease i
n infrarenal elastin without a corresponding decrease in collagen may
effect the compliance and integrity of the distal aorta. These anatomi
c differences may be important in predisposing the infrarenal aorta to
atherosclerosis and aneurysm formation. (C) 1995 Academic Press, Inc.