Purpose: To determine anatomicomorphological changes in the infrarenal portion of the abdominal aorta, we performed 645 dissections of the segment in corpses undergoing necropsy.
Methods: The aortas were removed from the corpses with a surgical technique; by means of a device that we designed, the external diameter of the artery was measured after luminal pressure was reestablished. This way, it was possible to avoid underestimation of the arterial diameter postmortem. The influence of age, sex, body size, arterial hypertension, chronic obstructive pulmonary disease, and coronary disease on the aortic diameter and the influence of different degrees of sclerosis on the infrarenal aorta wall were analyzed. Considering the diameters, aortas were regarded as "normal" when they did not present any ectasia, arteriomegaly, aneurysm, or hypoplasia.
Results: The sample involved 645 subjects whose ages ranged from 19 to 97 years (mean age, 55.8 years). Of the 645 subjects, 65.5% (423) were men, 34.5% (222) were women, 81% (523) were white, and 19% (122) were of another race. The diameters of arteries showing no anomalous dilatation (ectasis, arteriomegaly, or aneurysm) varied according to subject age, sex, body length, and the degree of atherosclerosis on the aorta wall (P <.01). Aortic diameters of those subjects with arterial hypertension, coronary disease, and chronic obstructive pulmonary disease were compared with the aortic diameters of control subjects, and significant differences were not shown (P >.05). Twenty-nine aneurysms were found (4.5% prevalence). Four were ruptured aneurysms, and all occurred in aortas with diameters larger than 5.0 cm.
Conclusion: The infrarenal aortic diameter enlarges with aging, and this enlargement occurs earlier in men than in women. Those subjects who had a longer body length and advanced sclerosis on the aorta wall had larger aortic diameters. There was a high prevalence of infrarenal aneurysms (4.5%), with rupture found solely in aortas with diameters larger than 5.0 cm.