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Kaczynski J, Home R, Shields K, Walters M, Whiteley W, Wardlaw J, Newby DE. Reproducibility of Transcranial Doppler ultrasound in the middle cerebral artery. Cardiovasc Ultrasound 2018; 16:15. [PMID: 30200977 PMCID: PMC6131943 DOI: 10.1186/s12947-018-0133-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 07/19/2018] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Transcranial Doppler ultrasound remains the only imaging modality that is capable of real-time measurements of blood flow velocity and microembolic signals in the cerebral circulation. We here assessed the repeatability and reproducibility of transcranial Doppler ultrasound in healthy volunteers and patients with symptomatic carotid artery stenosis. METHODS Between March and August 2017, we recruited 20 healthy volunteers and 20 patients with symptomatic carotid artery stenosis. In a quiet temperature-controlled room, two 1-h transcranial Doppler measurements of blood flow velocities and microembolic signals were performed sequentially on the same day (within-day repeatability) and a third 7-14 days later (between-day reproducibility). Levels of agreement were assessed by interclass correlation co-efficient. RESULTS In healthy volunteers (31±9 years, 11 male), within-day repeatability of Doppler measurements were 0.880 (95% CI 0.726-0.950) for peak velocity, 0.867 (95% CI 0.700-0.945) for mean velocity, and 0.887 (95% CI 0.741-0.953) for end-diastolic velocity. Between-day reproducibility was similar but lower: 0.777 (95% CI 0.526-0.905), 0.795 (95% CI 0.558-0.913), and 0.674 (95% CI 0.349-0.856) respectively. In patients (72±11 years, 11 male), within-day repeatability of Doppler measurements were higher: 0.926 (95% CI 0.826-0.970) for peak velocity, 0.922 (95% CI 0.817-0.968) for mean velocity, and 0.868 (95% CI 0.701-0.945) for end-diastolic velocity. Similarly, between-day reproducibility revealed lower values: 0.800 (95% CI 0.567-0.915), 0.786 (95% CI 0.542-0.909), and 0.778 (95% CI 0.527-0.905) respectively. In both cohorts, the intra-observer Bland Altman analysis demonstrated acceptable mean measurement differences and limits of agreement between series of middle cerebral artery velocity measurements with very few outliers. In patients, the carotid stenoses were 30-40% (n = 9), 40-50% (n = 6), 50-70% (n = 3) and > 70% (n = 2). No spontaneous embolisation was detected in either of the groups. CONCLUSIONS Transcranial Doppler generates reproducible data regarding the middle cerebral artery velocities. However, larger studies are needed to validate its clinical applicability. TRIAL REGISTRATION ClinicalTrial.gov (ID NCT 03050567), retrospectively registered on 15/05/2017.
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Affiliation(s)
- Jakub Kaczynski
- British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Chancellor’s Building, 49 Little France Crescent, Edinburgh, EH16 4SA UK
| | - Rachel Home
- College of Medicine and Veterinary Medicine, University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ UK
| | - Karen Shields
- Stroke Unit, Queen Elizabeth University Hospital, 1345 Govan Road, Glasgow, G51 4TF UK
| | - Matthew Walters
- College of Medical, Veterinary and Life Sciences, Wolfson Medical School Building, University of Glasgow, University Avenue, Glasgow, G12 8QQ UK
| | - William Whiteley
- Royal Infirmary of Edinburgh, 51 Little France Crescent, Old Dalkeith Road, Edinburgh, EH16 4SA UK
| | - Joanna Wardlaw
- Royal Infirmary of Edinburgh, 51 Little France Crescent, Old Dalkeith Road, Edinburgh, EH16 4SA UK
| | - David E. Newby
- British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, Chancellor’s Building, 49 Little France Crescent, Edinburgh, EH16 4SA UK
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Saedon M, Hutchinson CE, Imray CHE, Singer DRJ. ABCD 2 risk score does not predict the presence of cerebral microemboli in patients with hyper-acute symptomatic critical carotid artery stenosis. Stroke Vasc Neurol 2017; 2:41-46. [PMID: 28959490 PMCID: PMC5600015 DOI: 10.1136/svn-2017-000073] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 02/02/2017] [Indexed: 11/23/2022] Open
Abstract
Introduction ABCD2 risk score and cerebral microemboli detected by transcranial Doppler (TCD) have been separately shown to the predict risk of recurrent acute stroke. We studied whether ABCD2 risk score predicts cerebral microemboli in patients with hyper-acute symptomatic carotid artery stenosis. Participants and methods We studied 206 patients presenting within 2 weeks of transient ischaemic attack or minor stroke and found to have critical carotid artery stenosis (≥50%). 86 patients (age 70±1 (SEM: years), 58 men, 83 Caucasian) had evidence of microemboli; 72 (84%) of these underwent carotid endarterectomy (CEA). 120 patients (age 72±1 years, 91 men, 113 Caucasian) did not have microemboli detected; 102 (85%) of these underwent CEA. Data were analysed using X2 and Mann–Whitney U tests and receiver operating characteristic (ROC) curves. Results 140/206 (68%: 95% CI 61.63 to 74.37) patients with hyper-acute symptomatic critical carotid stenosis had an ABCD2 risk score ≥4. There was no significant difference in the NICE red flag criterion for early assessment (ABCD2 risk score ≥4) for patients with cerebral microemboli versus those without microemboli (59/86 vs 81/120 patients: OR 1.05 ABCD2 risk score ≥4 (95% CI 0.58 to 1.90, p=0.867)). The ABCD2 risk score was <4 in 27 of 86 (31%: 95% CI 21 to 41) embolising patients and in 39 of 120 (31%: 95% CI 23 to 39) without cerebral microemboli. After adjusting for pre-neurological event antiplatelet treatment (APT), area under the curve (AUC) of ROC for ABCD2 risk score showed no prediction of cerebral microemboli (no pre-event APT, n=57: AUC 0.45 (95% CI 0.29 to 0.60, p=0.531); pre-event APT, n=147: AUC 0.51 (95% CI 0.42 to 0.60, p=0.804)). Conclusions The ABCD2 score did not predict the presence of cerebral microemboli or carotid disease in over one-quarter of patients with symptomatic critical carotid artery stenosis. On the basis of NICE guidelines (refer early if ABCD2 ≥4), assessment of high stroke risk based on ABCD2 scoring may lead to inappropriate delay in urgent treatment in many patients.
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Affiliation(s)
- Mahmud Saedon
- Warwick Medical School, University of Warwick, Coventry, UK
| | | | - Christopher H E Imray
- Warwick Medical School, University of Warwick, Coventry, UK.,University Hospitals Coventry Warwickshire NHS Trust, Coventry, UK
| | - Donald R J Singer
- Warwick Medical School, University of Warwick, Coventry, UK.,Fellowship of Postgraduate Medicine, London, UK.,Yale School of Medicine, New Haven, Connecticut, USA
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Imray C. Lessons from altitude: cerebral perfusion insights and their potential translational clinical significance. Exp Physiol 2016; 101:1167-1172. [PMID: 27061345 DOI: 10.1113/ep085813] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 03/30/2016] [Indexed: 01/28/2023]
Abstract
What is the topic of this review? The long-held assumption that transcranial Doppler middle cerebral artery velocity is a surrogate for cerebral blood flow has been questioned in certain circumstances, particularly where tissue oxygenation changes. What advances does it highlight? Cerebral venous outflow restriction appears to be implicated in the development of high-altitude cerebral oedema. Rapid ascent to high altitude commonly results in acute mountain sickness and, on occasion, potentially fatal high-altitude cerebral oedema. The exact pathophysiological mechanisms behind these syndromes remain to be determined. One of the main theories to explain the development of acute mountain sickness is an increase in intracranial pressure. Vasogenic (extracellular water accumulation attributable to increased permeability of the blood-brain barrier) and cytotoxic (intracellular) oedema have also been postulated as potential mechanisms that underlie high-altitude cerebral oedema. Recently published findings derived from a very challenging field study (obtained at altitudes of up to 7950 m), substantiated by sea-level hypoxic magnetic resonance angiography studies, have given new insights into the maintenance of cerebral blood flow at altitude. This report provides new perspectives and potential mechanisms to account for the maintenance of cerebral oxygen delivery at high and extreme altitude. In particular, the long-held assumption that transcranial Doppler middle cerebral artery velocity is a surrogate for cerebral blood flow has been shown to be incorrect in certain circumstances. The emerging evidence for a potential third mechanism, namely the restrictive venous outflow hypothesis, in the development of high-altitude cerebral oedema, over and above the accepted vasogenic and cytotoxic hypotheses, is also appraised.
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Affiliation(s)
- Chris Imray
- Department of Vascular Surgery, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK.,Warwick Medical School, Warwick University, Coventry, UK.,Coventry University, Coventry, UK
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Regarding "Intraoperative use of dextran is associated with cardiac complications after carotid endarterectomy". J Vasc Surg 2013; 58:1167. [PMID: 24075115 DOI: 10.1016/j.jvs.2013.05.102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 05/15/2013] [Accepted: 05/17/2013] [Indexed: 11/20/2022]
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Jauch EC, Saver JL, Adams HP, Bruno A, Connors JJB, Demaerschalk BM, Khatri P, McMullan PW, Qureshi AI, Rosenfield K, Scott PA, Summers DR, Wang DZ, Wintermark M, Yonas H. Guidelines for the early management of patients with acute ischemic stroke: a guideline for healthcare professionals from the American Heart Association/American Stroke Association. Stroke 2013; 44:870-947. [PMID: 23370205 DOI: 10.1161/str.0b013e318284056a] [Citation(s) in RCA: 3207] [Impact Index Per Article: 291.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND AND PURPOSE The authors present an overview of the current evidence and management recommendations for evaluation and treatment of adults with acute ischemic stroke. The intended audiences are prehospital care providers, physicians, allied health professionals, and hospital administrators responsible for the care of acute ischemic stroke patients within the first 48 hours from stroke onset. These guidelines supersede the prior 2007 guidelines and 2009 updates. METHODS Members of the writing committee were appointed by the American Stroke Association Stroke Council's Scientific Statement Oversight Committee, representing various areas of medical expertise. Strict adherence to the American Heart Association conflict of interest policy was maintained throughout the consensus process. Panel members were assigned topics relevant to their areas of expertise, reviewed the stroke literature with emphasis on publications since the prior guidelines, and drafted recommendations in accordance with the American Heart Association Stroke Council's Level of Evidence grading algorithm. RESULTS The goal of these guidelines is to limit the morbidity and mortality associated with stroke. The guidelines support the overarching concept of stroke systems of care and detail aspects of stroke care from patient recognition; emergency medical services activation, transport, and triage; through the initial hours in the emergency department and stroke unit. The guideline discusses early stroke evaluation and general medical care, as well as ischemic stroke, specific interventions such as reperfusion strategies, and general physiological optimization for cerebral resuscitation. CONCLUSIONS Because many of the recommendations are based on limited data, additional research on treatment of acute ischemic stroke remains urgently needed.
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Registry Report on Kinetics of Rescue Antiplatelet Treatment to Abolish Cerebral Microemboli After Carotid Endarterectomy. Stroke 2013; 44:230-3. [DOI: 10.1161/strokeaha.112.676338] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Imray CH, Yow H, Tiivas C, Higman DJ. Emboli detection in asymptomatic carotid stenosis. Lancet Neurol 2010; 9:948-9; author reply 949. [PMID: 20864044 DOI: 10.1016/s1474-4422(10)70228-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Yow KH, Mahmood A, Marshall C, Higman D, Imray CHE. There is a growing realization of the important role of transcranial Doppler and intravenous antiplatelet therapy in the control of platelet microemboli and associated perioperative strokes. Eur J Vasc Endovasc Surg 2010; 39:654. [PMID: 20129802 DOI: 10.1016/j.ejvs.2009.11.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Accepted: 11/25/2009] [Indexed: 10/19/2022]
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Easton JD, Saver JL, Albers GW, Alberts MJ, Chaturvedi S, Feldmann E, Hatsukami TS, Higashida RT, Johnston SC, Kidwell CS, Lutsep HL, Miller E, Sacco RL. Definition and Evaluation of Transient Ischemic Attack. Stroke 2009; 40:2276-93. [PMID: 19423857 DOI: 10.1161/strokeaha.108.192218] [Citation(s) in RCA: 1171] [Impact Index Per Article: 78.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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van Dellen D, Tiivas CAS, Jarvi K, Marshall C, Higman DJ, Imray CHE. Transcranial Doppler ultrasonography-directed intravenous glycoprotein IIb/IIIa receptor antagonist therapy to control transient cerebral microemboli before and after carotid endarterectomy. Br J Surg 2008; 95:709-13. [PMID: 18425794 DOI: 10.1002/bjs.6204] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Patients with a transient focal neurological deficit, critical carotid stenosis and/or microemboli detected by transcranial Doppler ultrasonography (TCD) have a significant risk of stroke. The effect of tirofiban, a selective glycoprotein IIb/IIIa inhibitor, was assessed in patients with microembolic signals on TCD after transient ischaemic attacks or carotid endarterectomy (CEA). METHODS Thirty-three patients with microemboli on TCD (13 symptomatic preoperative, 19 postoperative, one both) were treated with tirofiban between 2002 and 2007. All patients had carotid stenosis greater than 70 per cent. TCD monitoring was used during and after tirofiban therapy. RESULTS The median (range) rate of microemboli decreased from 22 (4-260) per h before surgery and 81 (44-216) per h after surgery to 0 (0-9) per h in both groups (P < 0.001, Mann-Whitney U test). This occurred rapidly (preoperative median 30 min; postoperative median 45 min) and was well tolerated in all patients, with no serious adverse effects. CONCLUSION Cerebral microemboli were controlled by tirofiban both before and after CEA. Further study is required to compare the relative efficacy of tirofiban and dextran.
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Affiliation(s)
- D van Dellen
- Coventry and Warwickshire County Vascular Unit, University Hospitals Coventry and Warwickshire NHS Trust, Walsgrave Hospital, Coventry, UK
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Imray CHE, Pattinson KTS, Myers S, Chan CW, Hoar H, Brearey S, Collins P, Wright AD. Intrapulmonary and Intracardiac Shunting With Exercise at Altitude. Wilderness Environ Med 2008; 19:199-204. [DOI: 10.1580/07-weme-br-162.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Guías de práctica clínica sobre diabetes, prediabetes y enfermedades cardiovasculares: versión resumida. Rev Esp Cardiol 2007. [DOI: 10.1016/s0300-8932(07)75070-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Bammer R, Hope TA, Aksoy M, Alley MT. Time-resolved 3D quantitative flow MRI of the major intracranial vessels: initial experience and comparative evaluation at 1.5T and 3.0T in combination with parallel imaging. Magn Reson Med 2007; 57:127-40. [PMID: 17195166 PMCID: PMC3985842 DOI: 10.1002/mrm.21109] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Exact knowledge of blood flow characteristics in the major cerebral vessels is of great relevance for diagnosing cerebrovascular abnormalities. This involves the assessment of hemodynamically critical areas as well as the derivation of biomechanical parameters such as wall shear stress and pressure gradients. A time-resolved, 3D phase-contrast (PC) MRI method using parallel imaging was implemented to measure blood flow in three dimensions at multiple instances over the cardiac cycle. The 4D velocity data obtained from 14 healthy volunteers were used to investigate dynamic blood flow with the use of multiplanar reformatting, 3D streamlines, and 4D particle tracing. In addition, the effects of magnetic field strength, parallel imaging, and temporal resolution on the data were investigated in a comparative evaluation at 1.5T and 3T using three different parallel imaging reduction factors and three different temporal resolutions in eight of the 14 subjects. Studies were consistently performed faster at 3T than at 1.5T because of better parallel imaging performance. A high temporal resolution (65 ms) was required to follow dynamic processes in the intracranial vessels. The 4D flow measurements provided a high degree of vascular conspicuity. Time-resolved streamline analysis provided features that have not been reported previously for the intracranial vasculature.
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Affiliation(s)
- Roland Bammer
- Lucas Center, Department of Radiology, Stanford University, Stanford, California 94305-5488, USA.
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Imray CHE, Pattinson KTS. Potential role for TCD-directed antiplatelet agents in symptomatic carotid artery dissection. Stroke 2006; 37:767. [PMID: 16505347 DOI: 10.1161/01.str.0000204060.73207.c5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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