Abdominal aortic aneurysm wall mechanics and their relation to risk of rupture

Purpose: to see whether aneurysmal aortic wall mechanics can be used as a p redictor of abdominal aortic aneurysm (AAA) rupture. Method: among 285 individuals, followed conservatively for AAA and monitore d for aneurysm,growth and mall mechanics on at least one occasion at our in stitution between January 1991 and January 1998, eleven subsequently ruptur ed. Wall mechanics were estimated as stiffness (beta). This was calculated um diameter and pulsatile diameter change, determined non-invasively by an ultrasonic echo-tracking system and blood pressure obtained by the ausculta tory method. The results were compared with those of 121 individuals electi vely operated on for AAA. Results: ilo difference in aortic stiffness was found between those that su bsequently ruptured (beta = 35, median) compared to those non-ruptured (bet a = 38, median) AAAs (p = 0.855). There was no difference in diameter in ru ptured (58.8 mm) compared with non-ruptured (54.1 mm) AAAs (p = 0.129). All ruptured AAAs showed an expansion of diameter over time. Conclusion: this study shows no difference in aneurysmal aortic wall mechan ics in those AAAs that subsequently ruptured compared with electively opera ted AAAs. The results indicate that it is not Possible to use aneurysmal ao rtic wall stiffness as a predictor of rupture.