Increased anterior abdominal aortic wall motion: possible role in aneurysm pathogenesis and design of endovascular devices.
OBJECTIVE
To determine whether variations in aortic wall motion exist in mammalian species other than humans and to consider the potential implications of such variations.


METHODS
M-mode ultrasound was used to measure abdominal aortic wall motion in 4 animal species [mice (n=10), rats (n=8), rabbits (n=7), and pigs (n=5)], and humans (n=6). Anterior wall displacement, posterior wall displacement, and diastolic diameter were measured. The ratio of displacement to diameter and cyclic strain were calculated.


RESULTS
Body mass varied from 24.1+/-2.4 g (mouse) to 61.8+/-13.4 kg (human); aortic diameter varied from 0.53+/-0.07 mm (mouse) to 1.2+/-1 mm (human). Anterior wall displacement was 2.5 to 4.0 times greater than posterior among the species studied. The ratios of wall displacement to diastolic diameter were similar for the anterior (range 9.40%-11.80%) and posterior (range 2.49%-3.91%) walls among species. The ratio of anterior to posterior displacement (range 2.47-4.03) and aortic wall circumferential cyclic strain (range 12.1%-15.7%) were also similar. An allometric scaling exponent was experimentally derived relating anterior wall (0.377+/-0.032, R2=0.94) and posterior wall (0.378+/-0.037, R2=0.93) displacement to body mass.


CONCLUSIONS
Abdominal aortic wall dynamics are similar in animals and humans regardless of aortic size, wih more anterior than posterior wall motion. Wall displacement increases linearly with diameter, but allometrically with body mass. These data suggest increased dynamic strain of the anterior wall. Increased strain, corresponding to increased elastin fatigue, may help explain why human abdominal aortic aneurysms initially develop anteriorly. Aortic wall motion should be considered when developing endovascular devices, since asymmetric motion may affect device migration, fixation, and sealing.
Goergen
Craig J
CJ
Department of Bioengineering, Stanford University, CA 94305-5431, USA.
Johnson
Bonnie L
BL
Greve
Joan M
JM
Taylor
Charles A
CA
Zarins
Christopher K
CK
D000328:Adult; D000818:Animals; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging / Q000502:physiology*; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D001807:Blood Vessel Prosthesis; D019917:Blood Vessel Prosthesis Implantation / Q000295:instrumentation*; D001835:Body Weight; D004548:Elasticity; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011474:Prosthesis Design; D011673:Pulsatile Flow; D011817:Rabbits; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow; D012107:Research Design; D013045:Species Specificity; D013552:Swine; D014463:Ultrasonography