Abstract 675: Abdominal Aortic Aneurysm Rupture Often Occur Outside the Maximal Diameter Area and is Preceded by Rapid Local Growth
Objectives: Surveillance of abdominal aortic aneurysms (AAA) currently relies on maximal diameter (Dmax) measurements. However, the annual risk of rupture in AAAs with a Dmax smaller than 55 mm is over 1.5 percent and many large AAAs remain stable. It was recently shown that significant structural changes may occur locally in the aneurysm without affecting the Dmax. Our objective was to quantify ruptures of small AAAs and to relate the location and growth of the local rupture site to the Dmax.
Methods: Cases were included from a retrospective cohort of patients who presented with ruptured AAA in our catchment area between the years 2009-2013. Dmax was measured orthogonally to the centerline in the 50 aneurysms that had available computed tomography (CT) images. Local diameter at the rupture site and its centerline distance from the Dmax region was measured in 30 AAAs that had an identifiable rupture site, defined as active contrast extravasation or wall discontinuity adjacent to a hematoma. In nine patients who had undergone CT within two years before rupture and at the time of rupture, diameter growth rates at Dmax and rupture site were compared. All measurements were made from CT images using multi-planar reconstruction in a Sectra PACS workstation.
Results: Median diameter at rupture CT was 77 mm (range 46-120 mm). Two ruptured AAAs (4%) had a Dmax < 55 mm and five (10%) had a Dmax < 60 mm. Fifteen (50%) of the 30 identified rupture sites were located outside the Dmax region, nine (30%) at a centerline distance of 20 mm or greater. Six (20%) occurred at a local diameter smaller than 60 mm. The diameter growth rate was in six cases out of nine (67%) higher in the rupture site than in the Dmax region between the pre-rupture and rupture CTs but there was no general difference (medians 4.7 vs 4.9 mm/y, p = 0.89).
Conclusions: Four to ten percent of the ruptured aneurysms had small diameters. Ruptures often occurred outside the maximal diameter region, sometimes in segments with relatively small local diameters, and were preceded by rapid local diameter growth. Our results support the notion of considering the entire structure of an aneurysm, rather than sole reliance on maximal diameter measurements.
Author Disclosures: A. Siika: None. M. Lindquist Liljeqvist: None. R. Hultgren: None. T. Gasser: Employment; Significant; Christian Gasser is a scientific advisor at Vascops GmBH. Ownership Interest; Significant; Christian Gasser is a shareholder of Vascops GmbH. J. Roy: None.
- © 2015 by American Heart Association, Inc.