Dataset Information

Cerebrovascular Reactivity Assays Collateral Function in Carotid Stenosis.

ABSTRACT: In patients with carotid artery stenosis (CAS), the risk of stroke, its severity, and response to revascularization are strongly related to the availability of collateral blood flow. Unfortunately, there is poor agreement between observers in assessing collateral flow using flow-based imaging. We used changes in blood-oxygen-level-dependent (BOLD) MRI as a surrogate of changes in regional cerebral blood flow in response to a hypercapnic stimulus [i.e., cerebrovascular reactivity (CVR)] as indicating flow reserve ipsilateral to CAS. We hypothesized that some patients with hemodynamically significant CAS develop functional collateral flow as indicated by normalization of ipsilateral CVR. We identified 55 patients in our CVR database with various degrees of CAS assessed by angiography and classed them as <50% stenosis, 50-69% stenosis, 70-90% stenosis, >90% stenosis, and full occlusion. CVR was measured as the change in BOLD signal in response to changes in end-tidal partial pressure of CO2 (? BOLD/? PETCO2) and normalized voxel-wise relative to the mean and standard deviation of the CVR in the corresponding voxels of an atlas of 46 healthy controls (CVR z scores). CVR and z scores were then averaged over gray matter (GM) and white matter (WM) on each side of the middle cerebral artery (MCA) territory. As hypothesized, CVR varied for each severity of CAS. Ipsilateral MCA territory CVR was less than normal in each class, including that with <50% stenosis (Student t-test, two-tailed; p = 0.0014 for GM and p = 0.030 for WM), with a trend of decreasing average CVR with increasing stenosis. Remarkably, the considerable individual variability in MCA CVR included some patients with normal CVR in each class - including that with complete occlusion. We conclude that, in general, CAS depresses downstream vascular reserve, but the extent of collateralization is highly variable and not predictable from the degree of stenosis, including both <50% stenosis and complete occlusion. CVR may be the more reliable marker for recruitable collateral blood flow than degree of CAS.

SUBMITTER: Sobczyk O

PROVIDER: S-EPMC7528398 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Cerebrovascular Reactivity Assays Collateral Function in Carotid Stenosis.

Sobczyk Olivia O Sam Kevin K Mandell Daniel M DM Crawley Adrian P AP Venkatraghavan Lakshmikumar L McKetton Larissa L Poublanc Julien J Duffin James J Fisher Joseph A JA Mikulis David J DJ

Frontiers in physiology 20200901

In patients with carotid artery stenosis (CAS), the risk of stroke, its severity, and response to revascularization are strongly related to the availability of collateral blood flow. Unfortunately, there is poor agreement between observers in assessing collateral flow using flow-based imaging. We used changes in blood-oxygen-level-dependent (BOLD) MRI as a surrogate of changes in regional cerebral blood flow in response to a hypercapnic stimulus [i.e., cerebrovascular reactivity (CVR)] as indica ...[more]

PMID: 33041841

Similar Datasets

Project description:Background Comprehensive hemodynamic impairment mapping using blood oxygenation-level dependent (BOLD) cerebrovascular reactivity (CVR) can be used to identify hemodynamically relevant symptomatic unilateral carotid artery disease. Methods and Results This prospective cohort study was conducted between February 2015 and July 2020 at the Clinical Neuroscience Center of the University Hospital Zurich, Zurich, Switzerland. One hundred two patients with newly diagnosed symptomatic unilateral internal carotid artery (ICA) occlusion or with 70% to 99% ICA stenosis were included. An age-matched healthy cohort of 12 subjects underwent an identical BOLD functional magnetic resonance imaging examination. Using BOLD functional magnetic resonance imaging with a standardized CO2 stimulus, CVR impairment was evaluated. Moreover, embolic versus hemodynamic ischemic patterns were evaluated on diffusion-weighted imaging. Sixty-seven patients had unilateral ICA occlusion and 35 patients unilateral 70% to 99% ICA stenosis. Patients with ICA occlusion exhibited lower whole-brain and ipsilateral hemisphere mean BOLD-CVR values as compared with healthy subjects (0.12±0.08 versus 0.19±0.04, P=0.004 and 0.09±0.09 versus 0.18±0.04, P<0.001) and ICA stenosis cohort (0.12±0.08 versus 0.16±0.05, P=0.01 and 0.09±0.09 versus 0.15±0.05, P=0.01); however, only 40 (58%) patients of the cohort showed significant BOLD-CVR impairment. Conversely, there was no difference in mean BOLD-CVR values between healthy patients and patients with ICA stenosis, although 5 (14%) patients with ICA stenosis showed a significant BOLD-CVR impairment. No significant BOLD-CVR difference was discernible between patients with hemodynamic ischemic infarcts versus those with embolic infarct distribution (0.11±0.08 versus 0.13±0.06, P=0.12). Conclusions Comprehensive BOLD-CVR mapping allows for identification of hemodynamically relevant symptomatic unilateral carotid artery stenosis or occlusion.

Project description:PurposeTo project and compare the lifetime health benefits, health care costs, and incremental cost-effectiveness of a decision rule based on assessment of cerebrovascular reserve (CVR) compared with medical therapy and immediate revascularization in asymptomatic patients with carotid artery stenosis for prevention of stroke.Materials and methodsThe three strategies compared included immediate revascularization (carotid endarterectomy) and ongoing medical therapy (with antiplatelet, statin, and antihypertensive agents plus lifestyle modification), medical therapy-based treatment with revascularization only for patients who progressed, and use of a CVR-based decision rule for treatment in which patients with CVR impairment undergo immediate revascularization and all others receive medical therapy. A decision analytic model was developed to project lifetime quality-adjusted life years (QALYs) and costs for asymptomatic patients with carotid stenosis with 70%-89% carotid luminal narrowing at presentation. Risks of clinical events, costs, and quality-of-life values were estimated on the basis of those in published sources. The analysis was conducted from a health care system perspective, with health and cost outcomes discounted at 3%. Results Total costs per person and lifetime QALYs were lowest for the medical therapy-based strategy ($14 597, 9.848 QALYs), followed by CVR testing ($16 583, 9.934 QALYs) and immediate revascularization ($20 950, 9.940 QALYs). The incremental cost-effectiveness ratio for the CVR-based strategy compared with the medical therapy-based strategy was $23 000 per QALY and for the immediate revascularization versus the CVR-based strategy was $760 000 per QALY.Resultswere sensitive to variations in model inputs for revascularization costs and complication risks and baseline stroke risk.ConclusionCVR testing can be a cost-effective tool to identify asymptomatic patients with carotid stenosis who are most likely to benefit from revascularization.

Project description:The cerebral vascular network regulates blood flow distribution by adjusting vessel diameters, and consequently resistance to flow, in response to metabolic demands (neurovascular coupling) and changes in perfusion pressure (autoregulation). Deliberate changes in carbon dioxide (CO2) partial pressure may be used to challenge this regulation and assess its performance since CO2 also acts to change vessel diameter. Cerebrovascular reactivity (CVR), the ratio of cerebral blood flow (CBF) response to CO2 stimulus is currently used as a performance metric. However, the ability of CVR to reflect the responsiveness of a particular vascular region is confounded by that region's inclusion in the cerebral vascular network, where all regions respond to the global CO2 stimulus. Consequently, local CBF responses reflect not only changes in the local vascular resistance but also the effect of changes in local perfusion pressure resulting from redistribution of flow within the network. As a result, the CBF responses to CO2 take on various non-linear patterns that are not well-described by straight lines. We propose a method using a simple model to convert these CBF response patterns to the pattern of resistance responses that underlie them. The model, which has been used previously to explain the steal phenomenon, consists of two vascular branches in parallel fed by a major artery with a fixed resistance unchanging with CO2. One branch has a reference resistance with a sigmoidal response to CO2, representative of a voxel with a robust response. The other branch has a CBF equal to the measured CBF response to CO2 of any voxel under examination. Using the model to calculate resistance response patterns of the examined branch showed sigmoidal patterns of resistance response, regardless of the measured CBF response patterns. The sigmoid parameters of the resistance response pattern of examined voxels may be mapped to their anatomical location. We show an example for a healthy subject and for a patient with steno-occlusive disease to illustrate. We suggest that these maps provide physiological insight into the regulation of CBF distribution.

Project description:AimTo evaluate the relationship between carotid stenosis with variants in genes referred to inflammation and endothelial function.MethodsThere was a multi-center, cross sectional survey in southwestern China. The eight communities were selected at random in southwestern China. The residents aged ≥40 years volunteered to participate in face-to-face survey. Subjects with at least three of the aforementioned eight stroke related risk factors or a history of stroke were classified as high-risk population for stroke. A total of 2,377 subjects were the high-risk population for stroke in the eight communities, and degree of carotid stenosis was assessed by carotid ultrasound. Genotypes of 6 variants in 3 genes related to inflammation and endothelial function were examined. Gene-gene interaction was analyzed by generalized multifactor dimensionality reduction (GMDR).ResultsCarotid stenosis were found in 295 (12.41%) subjects, of whom 51 (17.29%) had moderate or severe stenosis. According to multivariate logistic regression analysis, we found that HABP2rs7923349TT was independent risk factor for carotid stenosis (OR, 1.96, 95% CI: 1.22-3.13, P = 0.005) and ITGA2rs1991013AG and HABP2rs7923349TT were independent risk factors for moderate to severe carotid stenosis (OR, 2.28, 95% CI: 1.28-4.07, P = 0.005; OR, 2.90, 95% CI: 1.19-7.08, P = 0.019). GMDR analysis showed that there was a significant gene-gene interaction between ITGA2 rs4865756 and HABP2 rs7923349, and the high-risk interactive genotype in the two variants was independently associated with a higher risk for carotid stenosis after adjusting the covariates (OR,1. 42, 95% CI 1.10-1.84, P = 0.008).ConclusionsPrevalence of carotid stenosis was very high in the high-risk stroke population in southwestern China. Variants in genes referred in endothelial function were associated with the carotid stenosis. The high-risk interactive genotype in ITGA2 rs4865756 and HABP2 rs7923349 was independently associated with a higher risk for carotid stenosis.

Dataset Information

Cerebrovascular Reactivity Assays Collateral Function in Carotid Stenosis.

Publications

Cerebrovascular Reactivity Assays Collateral Function in Carotid Stenosis.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets