title: Closure technique after carotid endarterectomy influences local hemodynamics.
abstract: BACKGROUND
  Meta-analysis supports patch angioplasty after carotid endarterectomy (CEA); however, studies indicate considerable variation in practice. The hemodynamic effect of a patch is unclear and this study attempted to elucidate this and guide patch width selection.
  
  
  METHODS
  Four groups were selected: healthy volunteers and patients undergoing CEA with primary closure, trimmed patch (5 mm), or 8-mm patch angioplasty. Computer-generated three-dimensional models of carotid bifurcations were produced from transverse ultrasound images recorded at 1-mm intervals. Rapid prototyping generated models for flow visualization studies. Computational fluid dynamic studies were performed for each model and validated by flow visualization. Mean wall shear stress (WSS) and oscillatory shear index (OSI) maps were created for each model using pulsatile inflow at 300 mL/min. WSS of <0.4 Pa and OSI >0.3 were considered pathological, predisposing to accretion of intimal hyperplasia. The resultant WSS and OSI maps were compared.
  
  
  RESULTS
  The four groups comprised 8 normal carotid arteries, 6 primary closures, 6 trimmed patches, and seven 8-mm patches. Flow visualization identified flow separation and recirculation at the bifurcation increased with a patch and was related to the patch width. Computational fluid dynamic identified that primary closure had the fewest areas of low WSS or elevated OSI but did have mild common carotid artery stenoses at the proximal arteriotomy that caused turbulence. Trimmed patches had more regions of abnormal WSS and OSI at the bifurcation, but 8-mm patches had the largest areas of deleteriously low WSS and high OSI. Qualitative comparison among the four groups confirmed that incorporation of a patch increased areas of low WSS and high OSI at the bifurcation and that this was related to patch width.
  
  
  CONCLUSIONS
  Closure technique after CEA influences the hemodynamic profile. Patching does not appear to generate favorable flow dynamics. However, a trimmed 5-mm patch may offer hemodynamic benefits over an 8-mm patch and may be the preferred option.
authors.affiliation: The Regional Vascular Unit, Liverpool Royal Hospital, Liverpool, United Kingdom. Electronic address: garethjamesharrison@yahoo.co.uk.
authors.forename: Gareth J
authors.initials: GJ
authors.lastname: Harrison
authors.affiliation: Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom.
authors.forename: Thien V
authors.initials: TV
authors.lastname: How
authors.affiliation: School of Engineering, University of Liverpool, Liverpool, United Kingdom.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Poole
authors.affiliation: The Regional Vascular Unit, Liverpool Royal Hospital, Liverpool, United Kingdom.
authors.forename: John A
authors.initials: JA
authors.lastname: Brennan
authors.affiliation: The Regional Vascular Unit, Liverpool Royal Hospital, Liverpool, United Kingdom.
authors.forename: Jagjeeth B
authors.initials: JB
authors.lastname: Naik
authors.affiliation: The Regional Vascular Unit, Liverpool Royal Hospital, Liverpool, United Kingdom.
authors.forename: S Rao
authors.initials: SR
authors.lastname: Vallabhaneni
authors.affiliation: The Regional Vascular Unit, Liverpool Royal Hospital, Liverpool, United Kingdom.
authors.forename: Robert K
authors.initials: RK
authors.lastname: Fisher
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017130:Angioplasty / Q000009:adverse effects / Q000295:instrumentation; D001783:Blood Flow Velocity; D002339:Carotid Arteries / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D002340:Carotid Artery Diseases / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D003198:Computer Simulation; D016894:Endarterectomy, Carotid; D004867:Equipment Design; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D011673:Pulsatile Flow; D012039:Regional Blood Flow; D015203:Reproducibility of Results; D013314:Stress, Mechanical; D016896:Treatment Outcome; D014463:Ultrasonography; D058106:Wound Closure Techniques / Q000009:adverse effects