Invited commentary

Abstract

Computational studies of carotid artery hemodynamics have been performed for almost three decades. We now know that the localized arterial dilation found exclusively in the carotid bulb produces disturbed flow patterns with low and oscillatory shear stress that can alter endothelial function and activate atherogenic cellular phenotypes. Intensified by the deleterious effects of systemic risk factors and high intramural stresses and strains, these hemodynamic conditions can stimulate arterial wall stiffening and thickening that can further perturb normal physiology. This vicious circle of abnormal hemodynamics and pathologic remodeling may produce plaques that can become unstable, presenting vascular surgeons with opportunities to intervene. Two of the most commonly used variations on the technique of carotid endarterectomy are primary closure and patch angioplasty. Whereas clinical evidence has historically advocated for patch use,1Brott T.G. Halperin J.L. Abbara S. Bacharach J.M. Barr J.D. Bush R.L. et al.2011 ASA/ACCF/AHA/AANN/AANS/ACR/ASNR/CNS/SAIP/SCAI/SIR/SNIS/SVM/SVS Guideline on the Management of Patients With Extracranial Carotid and Vertebral Artery Disease: a report of the American College of Cardiology Foundation/American Heart Association Task F.Circulation. 2011; 124: e54-e130Crossref PubMed Scopus (453) Google Scholar recent data suggest that benefits are only of borderline significance2Rerkasem K. Rothwell P.M. Systematic review of randomized controlled trials of patch angioplasty versus primary closure and different types of patch materials during carotid endarterectomy.Asian J Surg. 2011; 34: 32-40Crossref PubMed Scopus (68) Google Scholar or may not even be significant at all.3Avgerinos E.D. Chaer R.A. Naddaf A. El-Shazly O.M. Marone L. Makaroun M.S. Primary closure after carotid endarterectomy is not inferior to other closure techniques.J Vasc Surg. 2016; 64: 678-683.e1Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar This poses a question of whether increased clamp time, higher risk of cerebral ischemia, potential infectious issues, and patch-associated aneurysmal dilation are justified for every patient. In this study by Domanin et al, this argument is explored from a hemodynamic perspective whereby the authors compare flow characteristics in carotid arteries virtually repaired with primary closure and patch angioplasty. Because addition of the patch widened the carotid bifurcation, patch angioplasty was found to be associated with less favorable hemodynamics compared with primary closure. The authors conclude that patch use should be elective and performed with the purpose of re-creating the original shape of the carotid bifurcation rather than enlarging it. We arrived at similar conclusions in our computational analysis of carotid artery reconstruction, demonstrating more favorable flow patterns and lower intramural mechanical stresses for the artery repaired without a patch.4Kamenskiy A.V. Pipinos I.I. Dzenis Y.A. Gupta P.K. Jaffar Kazmi S.A. MacTaggart J.N. A mathematical evaluation of hemodynamic parameters after carotid eversion and conventional patch angioplasty.Am J Physiol Heart Circ Physiol. 2013; 305: H716-H724Crossref PubMed Scopus (19) Google Scholar To produce favorable hemodynamics with patching, our analysis demonstrated that the patch should be tailored to ensure smooth transition in arterial diameter, be placed anteriorly (as opposed to laterally), and be made of material that most closely matches the compliance of the recipient artery.5Kamenskiy A.V. MacTaggart J.N. Pipinos I.I. Gupta P.K. Dzenis Y.A. Hemodynamically motivated choice of patch angioplasty for the performance of carotid endarterectomy.Ann Biomed Eng. 2012; 41: 263-278Crossref PubMed Scopus (17) Google Scholar Patch compliance was particularly important as the mismatch in stiffness between synthetic patches and the host wall resulted in high stress and strain concentrations at the suture-artery interface, causing the posterior aspect of the artery to bulge out and to perturb flow and intramural stresses. Whereas these findings are merely suggestions offered by computational modeling, they have the potential to help clinicians choose the optimal type of repair material and geometry based on patient-specific arterial characteristics. Computational modeling of vascular physiology is frequently met by clinicians with skepticism as it is still in its infancy in describing complex mechanobiologic phenomena. There is much to be learned to improve fidelity of these models, and prospective validation in patients is a difficult next step to make these techniques clinically relevant. This cannot be achieved without synergistic collaborations between engineers and vascular surgeons. Sparking and nurturing these collaborations is the best way to make meaningful progress in making computational models useful to clinicians, as even the best of tools are only as good as the hands that use them. The opinions or views expressed in this commentary are those of the authors and do not necessarily reflect the opinions or recommendations of the Journal of Vascular Surgery or the Society for Vascular Surgery. Computational fluid dynamic comparison between patch-based and primary closure techniques after carotid endarterectomyJournal of Vascular SurgeryVol. 67Issue 3PreviewThe aim of the study was to provide, by means of computational fluid dynamics, a comparative analysis after carotid endarterectomy (CEA) between patch graft (PG) and primary closure (PC) techniques performed in real carotid geometries to identify disturbed flow conditions potentially involved in the development of restenosis. Full-Text PDF Open Archive