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Title: Geometric and haemodynamic changes after carotid intervention
Author: Harrison, Gareth
ISNI:       0000 0004 5368 9841
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2015
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Carotid endarterectomy has been demonstrated to reduce future stroke risk; however, stroke is a procedural risk. Therefore, to achieve the maximum benefit for patients, complications must be minimised. There are variations in the way that the operation is performed which may influence this peri-operative stroke risk. In particular, patch closure of the artery is a possible way of improving outcomes and the evidence is considered. Flow haemodynamics are considered to be a major aspect of the potential benefit with patch closure. The related evidence is presented, though the evidence to date is inadequate to prove that patching improves the haemodynamic profile sufficiently to improve outcomes. The hypothesis of a study is presented to try to answer this key question in carotid disease. Around one third of surgeons use primary closure with patching indicated with a median ICA diameter under 5mm. Of those surgeons who always use patch angioplasty around half use a full size patch of median 8mm diameter and the other half trim the patch width to a median of 6mm. Carotid geometry is complex but can be defined by using an index which uses the long and short axes or the cross-sectional area divided by the dimensions in the CCA proximal to endarterectomy; this index has been validated. Primary closure reduces the diameter and cross-sectional area in contrast to patch angioplasty which increases these dimensions in proportion to the width of the patch. Primary closure, in some cases, causes stenoses in the distal CCA which produces detrimental haemodynamics, whereas in those cases without a stenosis, physiological haemodynamics are produced. Patch closure produces less advantageous haemodynamics, however the larger 8mm patch is considerably worse than the trimmed 5mm patch. There is a direct link between geometry and haemodynamics. Increasing geometry index produces worse haemodynamics, the exception being a CCA stenosis in a primary closure. Increasing model size has only a limited effect on haemodynamics. This study affirms the practice of those surgeons who trim their patches. Very large bifurcations (an internal carotid diameter of around 8mm) are prone to low wall shear stresses and may be best repaired by primary closure.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (M.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: RD Surgery