title: In vivo assessment of rapid cerebrovascular morphological adaptation following acute blood flow increase.
abstract: OBJECTIVE
  Pathological extremes in cerebrovascular remodeling may contribute to basilar artery (BA) dolichoectasia and fusiform aneurysm development. Factors regulating cerebrovascular remodeling are poorly understood. To better understand hemodynamic influences on cerebrovascular remodeling, we examined BA remodeling following common carotid artery (CCA) ligation in an animal model.
  
  
  METHODS
  Rabbits were subjected to sham surgery (3 animals), unilateral CCA ligation (3 animals), or bilateral CCA ligation (5 animals). Transcranial Doppler ultrasonography and rotational angiography were used to compute BA flow, diameter, wall shear stress (WSS), and a tortuosity index on Days 0, 1, 4, 7, 14, 28, 56, and 84. Basilar artery tissues were stained and analyzed at Day 84. Statistical analysis was performed using orthogonal contrast analysis, repeated measures analysis of variance, or mixed regression analysis of repeated measures. Statistical significance was defined as a probability value < 0.05.
  
  
  RESULTS
  Basilar artery flow and diameter increased significantly after the procedure in both ligation groups, but only the bilateral CCA ligation group demonstrated significant differences between groups. Wall shear stress significantly increased only in animals in the bilateral CCA ligation group and returned to baseline by Day 28, with 52% of WSS correction occurring by Day 7. Only the bilateral CCA ligation group developed significant BA tortuosity, occurring within 7 days postligation. Unlike the animals in the sham and unilateral CCA ligation groups, the animals in the bilateral CCA ligation group had histological staining results showing a substantial internal elastic lamina fragmentation.
  
  
  CONCLUSIONS
  Increased BA flow results in adaptive BA remodeling until WSS returns to physiological baseline levels. Morphological changes occur rapidly following flow alteration and do not require chronic insult to affect substantial and significant structural transformation. Additionally, it appears that there exists a flow-increase threshold that, when surpassed, results in significant tortuosity.
authors.affiliation: Toshiba Stroke Research Center, State University of New York at Buffalo, New York 14214, USA.
authors.forename: Yiemeng
authors.initials: Y
authors.lastname: Hoi
authors.forename: Ling
authors.initials: L
authors.lastname: Gao
authors.forename: Markus
authors.initials: M
authors.lastname: Tremmel
authors.forename: Rocco A
authors.initials: RA
authors.lastname: Paluch
authors.forename: Adnan H
authors.initials: AH
authors.lastname: Siddiqui
authors.forename: Hui
authors.initials: H
authors.lastname: Meng
authors.forename: J
authors.initials: J
authors.lastname: Mocco
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001488:Basilar Artery / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology*; D001921:Brain / Q000098:blood supply; D017536:Carotid Artery, Common / Q000601:surgery; D002533:Cerebral Angiography; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D023421:Models, Animal; D011817:Rabbits; D012039:Regional Blood Flow / Q000502:physiology*; D012044:Regression Analysis; D017585:Ultrasonography, Doppler, Transcranial; D014664:Vasodilation / Q000502:physiology