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Title: A comparison of sub-clinical neurological effects caused by open and endovascular treatment of carotid artery stenosis
Author: Brightwell, Robert Edward
ISNI:       0000 0001 3480 1146
Awarding Body: Imperial College London (University of London)
Current Institution: Imperial College London
Date of Award: 2008
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Stroke is caused by atherosclerosis (furring up) of the carotid artery in up to 40% of cases. This area of narrowing'can be treated to reduce future stroke risk. Traditionally the narrowing has been treated by vascular surgeons performing an open operation on the artery - termed carotid endarterectomy (CEA) - which involves working on the artery under direct vision. The artery needs to have the flow of blood stopped within it for a variable period of time in order to completely remove the lesion. More recently a less invasive approach has gathered support. In carotid artery angioplasty and stenting (CAS - performed by vascular surgeons, radiologists and cardiologists) a wire is passed via the femoral artery across the narrowed segment of artery. A balloon is then used to stretch the artery and plaque, followed by the insertion of a stent - a sort of wire scaffold to support diseased area of the vessel and overcome the elastic recoil of the artery. Clinical outcome and complication rates for both procedures have been declining, prompting the search for more subtle and sensitive measures. This thesis describes what is known so far about the sub-clinical outcomes of each procedure, and analyses the results of each technique as performed at St Mary's Hospital, London. A multimodal approach has been used to achieve this aim. Trans-cranial Doppler has been performed to record the number of presumed emboli impacting on the brain, as well as measuring intra-operative changes in blood flow to the brain. Biomarkers of brain injury that are well recognised have been used, as have newer tests that are still under development by biomedical research companies. ELISA has formed the mainstay of this component of the comparison of CEA and CAS. Changes in the functional ability of the patient's brain have been assessed using a robust battery of . neuropsychometric tests performed before and after the surgical intervention. This has been studied previously, but never according to the consensus guidelines produced by cardiac surgeons investigating similar changes after various forms of coronary artery bypass grafting. Little is known about the effect of CEA versus CAS on the intra-cerebral blood flow. The imaging component of this study used specialist Computed Tomography Perfusion scans to take measurements, and note changes, in brain blood flow in the short and mid term post-operatively. In the various chapters each of these outcome measures have been correlated to the other. For example, determining whether a rise in biomarkers of brain injury can predict which patient may develop a post-operative neuropsychometric deficit, or whether those with enhanced neuropsychometric performance have improved brain perfusion. The later experimental chapters involve radiological and histopathological analysis of carotid plaques to try and help determine which ones pose a greater risk to the patient in terms of clinical and subclinical neurological deficit. Radiological appearances of carotid plaques are also correlated with electron microscopic findings of the filters used to catch debris dislodged during the CAS procedure, thereby preventing peri-operative stroke. The final chapter summarises some of the thesis' key findings and highlights some potential areas for exploitation by future research.
Supervisor: Not available Sponsor: Not available
Qualification Name: MD Qualification Level: Doctoral
EThOS ID:  DOI: Not available