Abdominal aortic aneurysm: a general defect in the vasculature with focal manifestations in the abdominal aorta?

PURPOSE

It has been suggested that abdominal aortic aneurysms (AAA) develop as a result of an alteration in the systemic connective tissue metabolism. This might change wall mechanics and diameter, not only in the AAA but also in the rest of the vascular system. This hypothesis was tested by studying the mechanical properties of AAAs as well as the common carotid artery (CCA) in the same patient population.

METHODS

AAA and carotid artery stiffness (beta) was studied in 121 individuals (101 men, 20 women) who were admitted for elective repair of AAA. Stiffness (beta) was calculated from diameter and pulsatile diameter change determined noninvasively from an ultrasonic echo-tracking system and blood pressure obtained by the auscultatory method. The results were compared with those of healthy individuals of corresponding age and gender published elsewhere.

RESULTS

The stiffness of the AAA was increased in both men and women (p = 0.0001). The increase was more pronounced in women compared with men (p = 0.0003) to a mean of 435% and 189% of the normal predicted values, respectively. In the CCA, the stiffness was increased in men (p = 0.027) and in women (p = 0.0001) to a mean of 131% and 149% of the normal predicted values, respectively. A significant correlation between stiffness in the aneurysm and in the carotid artery was seen (p = 0.0031). The carotid diameter was unchanged in men (p = 0.924) and in women (p = 0.070) if adjusted for the difference in blood pressure between the individuals with AAAs and control subjects. There was no correlation between stiffness and diameter of the aneurysm in men (r = 0.16, p = 0.119) nor in women (r = 0.12, p = 0.598).

CONCLUSIONS

This investigation demonstrated altered mechanical properties of the aneurysmal wall as well as in the CCA in individuals with AAAs. The normal age- and gender-related differences seen in the healthy aorta and CCA vanished. The results suggest that AAA is a generalized process of the vasculature with focal manifestation in the abdominal aorta.