Carotid Endarterectomy Improves Cerebrovascular Reserve Capacity Preferentially in Patients with Preoperative Impairment as Indicated by Asymmetric BOLD Response to Hypercapnia

Article (PDF Available)inEuropean journal of vascular and endovascular surgery: the official journal of the European Society for Vascular Surgery 38(5):546-51 · October 2009with57 Reads
DOI: 10.1016/j.ejvs.2009.06.010 · Source: PubMed
Abstract
In patients with symptomatic carotid artery disease the predominant mechanism causing ischaemic injury is considered to be thromboembolic, however compromise of cerebral haemodynamics is considered to be a significant factor. Removal of the embolic source is accepted as the major benefit from Carotid Endarterectomy (CEA), however improvement in cerebral haemodynamics may be another beneficial outcome as suggested by Transcranial doppler (TCD). Blood Oxygen Level-Dependent (BOLD) hypercapnia functional Magnetic Resonance imaging (fMRI) can be used to map the Cerebrovascular Reserve (CVR). The aim of this study was to assess the effects of carotid surgery on cerebral haemodynamics in patients with carotid artery disease using a hypercapnia BOLD fMRI and assessment of hemispheric asymmetry.
1 Figures
    • In patients with tight intracranial arterial stenosis, this imaging may identify patients at risk of a failure of a well carried out medical treatment and help better select patients likely to benefit from endovascular treatment (Figs. 3 and 4) [198]. The imaging of cerebral vasoreactivity shows an improvement , or even normalization, of the vascular reserve after the surgical treatment of a carotid stenosis [197,220,221], moyamoya disease [195,222—226] or tight intracranial arterial stenosis (Fig. 4).
    [Show abstract] [Hide abstract] ABSTRACT: The functional imaging of perfusion enables the study of its properties such as the vasoreactivity to circulating gases, the autoregulation and the neurovascular coupling. Downstream from arterial stenosis, this imaging can estimate the vascular reserve and the risk of ischemia in order to adapt the therapeutic strategy. This method reveals the hemodynamic disorders in patients suffering from Alzheimer's disease or with arteriovenous malformations revealed by epilepsy. Functional MRI of the vasoreactivity also helps to better interpret the functional MRI activation in practice and in clinical research.
    Article · Sep 2013
    • To prevent ischemic stroke, patients with severe carotid stenosis often benefit from interventions, such as carotid endarterectomy (CEA) and carotid angioplasty with stent Radiology Research and Practice 5 placement (CAS)727374. Recently, studies have reported that patients with carotid stenosis, who showed impaired CVR before carotid intervention, had great CVR improvement after CEA or CAS [5, 6]. This finding is probably due to an improvement in vasodilatory ability, indicating return of vascular reserve capacity.
    File · Data · Aug 2012 · Medical science monitor: international medical journal of experimental and clinical research
    • To prevent ischemic stroke, patients with severe carotid stenosis often benefit from interventions, such as carotid endarterectomy (CEA) and carotid angioplasty with stentTime (s)placement (CAS)[72][73][74]. Recently, studies have reported that patients with carotid stenosis, who showed impaired CVR before carotid intervention, had great CVR improvement after CEA or CAS[5,6]. This finding is probably due to an improvement in vasodilatory ability, indicating return of vascular reserve capacity.
    [Show abstract] [Hide abstract] ABSTRACT: Impaired cerebrovascular reactivity (CVR), a predictive factor of imminent stroke, has been shown to be associated with carotid steno-occlusive disease. Magnetic resonance imaging (MRI) techniques, such as blood oxygenation level-dependent (BOLD) and arterial spin labeling (ASL), have emerged as promising noninvasive tools to evaluate altered CVR with whole-brain coverage, when combined with a vasoactive stimulus, such as respiratory task or injection of acetazolamide. Under normal cerebrovascular conditions, CVR has been shown to be globally and homogenously distributed between hemispheres, but with differences among cerebral regions. Such differences can be explained by anatomical specificities and different biochemical mechanisms responsible for vascular regulation. In patients with carotid steno-occlusive disease, studies have shown that MRI techniques can detect impaired CVR in brain tissue supplied by the affected artery. Moreover, resulting CVR estimations have been well correlated to those obtained with more established techniques, indicating that BOLD and ASL are robust and reliable methods to assess CVR in patients with cerebrovascular diseases. Therefore, the present paper aims to review recent studies which use BOLD and ASL to evaluate CVR, in healthy individuals and in patients with carotid steno-occlusive disease, providing a source of information regarding the obtained results and the methodological difficulties.
    Full-text · Article · Jun 2012
    • Waaijer et al. [1] concluded that relative CT perfusion values based on interhemispheric comparison are better suited (compared with absolute perfusion CT values) for demonstrating changes in cerebral perfusion after CEA or stent placement in patients with unilateral symptomatic carotid artery stenosis. Goode et al. [16] found that patients with abnormal preoperative asymmetry of cerebrovascular reserve showed greater hemodynamic improvement following CEA, based on pre-and post-CEA functional MRI study of 17 patients with symptomatic artery stenosis. Med Sci Monit, 2011; 17(5): CR297-303 Nocuń A et al – Perfusion changes after CEA
    [Show abstract] [Hide abstract] ABSTRACT: Association between preoperative perfusion pattern and reperfusion after carotid endarterectomy (CEA) is an important yet unexplored topic. Therefore, the aim of our study was to determine whether 99mTc-ECD single-photon emission computed tomography (SPECT) performed before carotid endarterectomy in patients with internal carotid artery (ICA) stenosis may be helpful in predicting early perfusion changes after revascularization. The examined group consisted of 30 patients (mean age 67.4±9.6 years) with ICA stenosis who underwent CEA. Infarction was demonstrated on computed tomography (CT) in 12 cases. Brain perfusion SPECT was performed 1-3 days before CEA and 3-5 days after the surgery. Voxel-based analysis was carried out with Brain SPECT Quantification software. For evaluation of preoperative interhemispheric asymmetry of perfusion, the percentage asymmetry index (AI) was calculated. For comparison of perfusion before and after CEA, the percentage relative difference (RD) was computed. Before CEA, cerebral hypoperfusion was seen in 26 cases, including 15 participants with normal CT. After CEA, the following changes of perfusion were observed: perfusion increase n=18 (ipsilateral and bilateral), deterioration n=1, mixed patterns n=2, no change n=9. In patients with preoperative ipsilateral hypoperfusion and perfusion increase after CEA, AI correlated significantly with RD (r=0.48, p=0.04). Our results suggest that perfusion increase 3-5 days after CEA is higher in patients with greater ipsilateral asymmetry index. Evaluation of preoperative AI may help to identify patients in whom rapid reperfusion is more likely.
    Full-text · Article · May 2011
  • [Show abstract] [Hide abstract] ABSTRACT: Carotid intervention for stroke prevention in the form of carotid artery stenting has been performed in clinical trials since the beginning of the 1980’s. Improvements in the operative technique and pharmacology used during the procedure have reduced complication rates since stenting began. Long term follow up of the Sheffield data set has shown that patient selection has the most impact on reducing adverse outcomes from the procedure. Multivariable analysis of the Sheffield database detailed in this thesis has shown that retinal events have a lower risk of adverse outcomes than cerebral events, and clopidogrel use at the time of stenting prevents adverse events. Recurrent stenosis of more than 50% also increases risk for recurrent stroke in the long term and therefore warrants a long term surveillance programmes in stented patients. It was possible to show from the same analysis that stenting patients as a routine procedure prior to cardiac surgery had no immediate benefit in reducing operative stroke risk from the procedure. The EPICAS study was developed from these initial observations to investigate the effects of variability in response to clopidogrel on outcomes. Using transcranial Doppler detected embolic events as a clinical endpoint for comparison with the clopidogrel dependant pathways of platelet activation the study hoped to show a direct effect of the degree of platelet inhibition on the number of emboli detected. This was not shown to be the case in the patients studied as part of this work. Patients classified as non responders to clopidogrel had no difference in emboli counts before and after the stenting procedure (p = 0.24). The results suggest that a variance in response to clopidogrel is unlikely to be clinically significant even in larger cohorts of patients.
    Full-text · Thesis · Aug 2010 · Medical science monitor: international medical journal of experimental and clinical research
  • [Show abstract] [Hide abstract] ABSTRACT: CVR is a measure of cerebral hemodynamic impairment. A recently validated technique quantifies CVR by using a precise CO(2) vasodilatory stimulus and BOLD MR imaging. Our aim was to determine whether preoperative CO(2) BOLD CVR predicts the hemodynamic effect of ECIC bypass surgery in patients with intracranial steno-occlusive disease. Twenty-five patients undergoing ECIC bypass surgery for treatment of intracranial stenosis or occlusion were recruited. CVR was measured preoperatively and postoperatively and expressed as %ΔBOLD MR signal intensity per mm Hg ΔPetCO(2). Using normative data from healthy subjects, we stratified patients on the basis of preoperative CVR into 3 groups: normal CVR, reduced CVR, and negative (paradoxical) CVR. Wilcoxon 2-sample tests (2-sided, α = 0.05) were used to determine whether the 3 groups differed with respect to change in CVR following bypass surgery. The group with normal preoperative CVR demonstrated no significant change in CVR following bypass surgery (mean, 0.22% ± 0.05% to 0.22% ± 0.01%; P = .881). The group with reduced preoperative CVR demonstrated a significant improvement following bypass surgery (mean, 0.08% ± 0.05% to 0.21 ± 0.08%; P < .001), and the group with paradoxical preoperative CVR demonstrated the greatest improvement (mean change, -0.04% ± 0.03% to 0.27% ± 0.03%; P = .028). Preoperative measurement of CVR by using CO(2) BOLD MR imaging predicts the hemodynamic effect of ECIC bypass in patients with intracranial steno-occlusive disease. The technique is potentially useful for selecting patients for surgical revascularization.
    Full-text · Article · Mar 2011
Show more