Nascent aneurysm formation at the basilar terminus induced by hemodynamics.
OBJECTIVE
Hemodynamic insults at arterial bifurcations are hypothesized to play a key role in intracranial aneurysm formation. This study investigates aneurysm-initiating vascular responses at the rabbit basilar terminus subsequent to common carotid artery ligation.


METHODS
Nine adult female New Zealand white rabbits were subjected to sham, unilateral, or bilateral common carotid artery ligation to produce varying degrees of compensatory basilar artery flow increase. Basilar artery flow velocity and geometry were monitored by transcranial Doppler and rotational angiography, respectively, for 12 weeks after surgery. Bifurcation tissues were harvested at 12 weeks and examined histologically. From the histological sections, we quantified the destructive structural changes at the basilar terminus and correlated them with the basilar artery flow rate increase.


RESULTS
Subsequent to common carotid artery ligation, basilar artery flow rate increased by 105% to 900% at the maximum. All common carotid artery-ligated rabbits presented nascent aneurysm formation characterized by a bulge with thinned media and absent internal elastic lamina near the basilar terminus. We defined a nascent aneurysm index based on a multiplicative combination of the local destructive remodeling lengths measured at the nascent aneurysm. The nascent aneurysm index strongly correlated with the increase in basilar artery flow rate with R(2)=0.91.


CONCLUSIONS
Without other known predisposition, flow increase alone at the basilar bifurcation can lead to a nascent aneurysm. This nascent aneurysm formation is dose-dependent on basilar artery flow increase.
Gao
Ling
L
Toshiba Stroke Research Center, State University of New York at Buffalo, 3435 Main Street, Buffalo, NY 14214, USA.
Hoi
Yiemeng
Y
Swartz
Daniel D
DD
Kolega
John
J
Siddiqui
Adnan
A
Meng
Hui
H
D000818:Animals; D001488:Basilar Artery / Q000473:pathology*; D001783:Blood Flow Velocity; D002339:Carotid Arteries / Q000473:pathology; D002533:Cerebral Angiography / Q000379:methods*; D004195:Disease Models, Animal; D005260:Female; D006439:Hemodynamics; D002532:Intracranial Aneurysm / Q000473:pathology*; D008953:Models, Anatomic; D011817:Rabbits; D013997:Time Factors