Prediction of Rupture Sites in Abdominal Aortic Aneurysms After Finite Element Analysis.
OBJECTIVE
To associate regions of highest local rupture risk from finite element analysis (FEA) to subsequent rupture sites in abdominal aortic aneurysms (AAA).


METHODS
This retrospective multicenter study analyzed computed tomography angiography (CTA) data from 13 asymptomatic AAA patients (mean age 76 years; 8 men) experiencing rupture at a later point in time between 2005 and 2011. All patients had CTA scans before and during the rupture event. FEA was performed to calculate peak wall stress (PWS), peak wall rupture risk (PWRR), rupture risk equivalent diameters (RRED), and the intraluminal thrombus volume (ILTV). PWS and PWRR locations in the prerupture state were compared with subsequent CTA rupture findings. Visible contrast extravasation was considered a definite (n=5) rupture sign, while a periaortic hematoma was an indefinite (n=8) sign. A statistical comparison was performed between the 13-patient asymptomatic AAA group before and during rupture and a 23-patient diameter-matched asymptomatic AAA control group that underwent elective surgery.


RESULTS
The asymptomatic AAAs before rupture showed significantly higher PWRR and RRED values compared to the matched asymptomatic AAA control group (median values 0.74 vs 0.52 and 77 vs 59 mm, respectively; p<0.0001 for both). No statistical differences could be found for PWS and ILTV. Ruptured AAAs showed the highest maximum diameters, PWRR, and RRED values. In 7 of the ruptured AAAs (2 definite and 5 indefinite rupture signs), CTA rupture sites correlated with prerupture PWRR locations.


CONCLUSIONS
The location of the PWRR in unruptured AAAs predicted future rupture sites in several cases. Asymptomatic AAA patients with high PWRR and RRED values have an increased rupture risk.
Department of Vascular and Endovascular Surgery, Ruprecht-Karls University Heidelberg, Germany philipp.erhart@med.uni-heidelberg.de.
Philipp
P
Erhart
Department of Surgical Sciences, Karolinska Hospital, Stockholm, Sweden.
Joy
J
Roy
Department of Vascular Surgery, St. Antonius Hospital, Nieuwegein, the Netherlands.
Jean-Paul P M
JP
de Vries
Department of Surgical Sciences, Karolinska Hospital, Stockholm, Sweden.
Moritz Lindquist
ML
Liljeqvist
Department of Neurology, Ruprecht-Karls University Heidelberg, Germany.
Caspar
C
Grond-Ginsbach
Department of Vascular and Endovascular Surgery, Ruprecht-Karls University Heidelberg, Germany.
Alexander
A
Hyhlik-Dürr
Department of Vascular and Endovascular Surgery, Ruprecht-Karls University Heidelberg, Germany.
Dittmar
D
Böckler
D000368:Aged; D000369:Aged, 80 and over; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery; D017544:Aortic Aneurysm, Abdominal / Q000150:complications* / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery; D001019:Aortic Rupture / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology; D001027:Aortography / Q000379:methods; D001696:Biomechanical Phenomena; D017558:Elective Surgical Procedures; D005060:Europe; D005260:Female; D020342:Finite Element Analysis; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D012189:Retrospective Studies; D012307:Risk Factors; D013314:Stress, Mechanical; D014057:Tomography, X-Ray Computed; D014656:Vascular Surgical Procedures
abdominal aortic aneurysm; aneurysm rupture; finite element analysis; intraluminal thrombus; rupture prediction; wall stress