Change of Hemodynamics and Cerebral Functions After Carotid Artery Revascularization

Hypothesis and Significance: We hypothesize that hemodynamically changes after carotid artery revascularization influence the cerebral function or carotid artery patency. If cognitive improvement or impairment and carotid artery restenosis can be demonstrated relate to hemodynamic remodeling in these patients, then we will have established a new prognostic factor for carotid revascularization independent of the existing study.

Specific Aim: 1) To compare the impact of carotid artery revascularization on long-term post-operative baroreceptor function and on cognitive brain function, and analyze their influence on clinical outcome. The specific goal is to assess the potential correlation between post-operative autonomic and cognitive function.

2. To assess the solicitation on the carotid wall due to CAS as compared to CEA through structural analysis and mechanical modeling. The specific goal is to assess the potential correlation between stenting, wall damage, baroceptor impairment, and late neurological sequelae. 3) To assess the post-operative carotid hemodynamics combining medical image analysis, clinical data, and computer simulations. The specific goal aims at correlating both local (e.g., wall shear stress (WSS), oscillatory shear index (OSI), relative residence time (RRT)) and global phenomena (controlateral flow, arterial stiffening) with baroreflex function and post-operative neurological outcomes.

Cognitive Assessment. HALO will use existing cognitive assessment infrastructure. Cognitive assessments in our study must take place prior to revascularization or within two weeks after assignment to medical therapy alone. Testing is repeated at 44 days, and every year thereafter up to 4 years. At each test interval, a composite (mean) Z-score is derived from published normative samples for each test outcome. The primary outcome will be at 1 year in which the change in the composite Z-score from baseline will be calculated. Covariates will include age, education and depression. The test battery will be administered the same way for all enrolled patients. The cognitive domains being assessed in HALO are entirely consistent with those encompassed within the NINDS Common Data Elements (CDE).

Imaging protocol. Multimodal MRI, including routine parenchymal sequences and PWI utilizing dynamic susceptibility contrast technique, will be acquired at each participating HALO site. Imaging will take place within 14 days after HALO enrollment and prior to any intervention (carotid artery revascularization).