Influences of aortic motion and curvature on vessel expansion in murine experimental aneurysms.
OBJECTIVE
To quantitatively compare aortic curvature and motion with resulting aneurysm location, direction of expansion, and pathophysiological features in experimental abdominal aortic aneurysms (AAAs).


RESULTS
MRI was performed at 4.7 T with the following parameters: (1) 3D acquisition for vessel geometry and (2) 2D cardiac-gated acquisition to quantify luminal motion. Male 24-week-old mice were imaged before and after AAA formation induced by angiotensin II (AngII)-filled osmotic pump implantation or infusion of elastase. AngII-induced AAAs formed near the location of maximum abdominal aortic curvature, and the leftward direction of expansion was correlated with the direction of suprarenal aortic motion. Elastase-induced AAAs formed in a region of low vessel curvature and had no repeatable direction of expansion. AngII significantly increased mean blood pressure (22.7 mm Hg, P<0.05), whereas both models showed a significant 2-fold decrease in aortic cyclic strain (P<0.05). Differences in patterns of elastin degradation and localization of fluorescent signal from protease-activated probes were also observed.


CONCLUSIONS
The direction of AngII aneurysm expansion correlated with the direction of motion, medial elastin dissection, and adventitial remodeling. Anterior infrarenal aortic motion correlated with medial elastin degradation in elastase-induced aneurysms. Results from both models suggest a relationship between aneurysm pathological features and aortic geometry and motion.
Department of Bioengineering, Stanford University, 318 Campus Dr., Stanford, CA 94305-5431, USA. cgoergen@stanford.edu
Craig J
CJ
Goergen
Junya
J
Azuma
Kyla N
KN
Barr
Lars
L
Magdefessel
Dara Y
DY
Kallop
Alvin
A
Gogineni
Amarjeet
A
Grewall
Robby M
RM
Weimer
Andrew J
AJ
Connolly
Ronald L
RL
Dalman
Charles A
CA
Taylor
Philip S
PS
Tsao
Joan M
JM
Greve
D000804:Angiotensin II / Q000009:adverse effects*; D000818:Animals; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology*; D017544:Aortic Aneurysm, Abdominal / Q000139:chemically induced* / Q000473:pathology / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D001794:Blood Pressure / Q000502:physiology; D018450:Disease Progression; D004549:Elastin / Q000378:metabolism; D006973:Hypertension / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D023421:Models, Animal; D008955:Models, Cardiovascular; D014463:Ultrasonography
D000804:Angiotensin II; D004549:Elastin