In the context of hemodialysis vascular\naccesses, the best practice encouraged by international guidelines is the\ncreation of a native fistula, i.e., the direct surgical connection between an\nartery and a vein, which however is not always feasible in all patients (e.g.\nelderly, diabetics, patients with high Body Mass Index), and usually takes 6-8\nweeks to reach a sufficient maturation stage to allow for puncturing.\nTherefore, in case of compromised vasculature and\/or when early cannulation (within\n24-48 hours after access creation) is needed, synthetic grafts are used, e.g.\nmade of ePTFE (expanded polytetrafluoroethylene) or polyurethane. However,\nprosthetic grafts carry a lifetime risk of thrombosis, stenosis and infection and\nthe 2-year primary patency for ePTFE arteriovenous grafts for hemodialysis\nranges from 30% to 40%.<\/p>\n\n\n\n
The most common<\/strong> mechanisms of failure<\/strong> for autologous\n(venous) and synthetic grafts, implanted either in arteriovenous or arterial\ndistricts, are known to be thrombosis due to platelet activation in the short\nterm (\u2248 weeks) and stenosis due to neointimal hyperplasia in the midterm (\u2248\nmonths).<\/strong><\/p>\n\n\n\n Platelet activation<\/strong> \u2013 the initial step towards thromboembolic\nevents – may occur due to the contact of blood cells with non-endothelial\nsurfaces, but also as a consequence of shear-related phenomena.<\/p>\n\n\n\n Neointimal hyperplasia<\/strong>, instead, refers to a process in which the\nintima gets thicker due to the presence of vascular smooth muscle cells and\nproteoglycan-rich extracellular matrix located between the endothelium and the\ninternal elastic lamina.<\/p>\n\n\n\n Although there is not a general consensus on the molecular mechanisms\nleading to grafts\u2019 failure, researchers agree that the common denominator at the basis of platelet activation and\nneointimal hyperplasia may be the difference in mechanical properties \u2013 and\nspecifically in radial compliance – <\/strong>between grafts and recipient vessels\n(phenomenon known as \u201ccompliance mismatch<\/strong>\u201d),\nwhich leads to disturbances in shear\nstress<\/strong> due to non-physiological hemodynamics and to stress concentration at the anastomosis<\/strong><\/p>\n","protected":false},"excerpt":{"rendered":" In the context of hemodialysis vascular accesses, the best practice encouraged by international guidelines is the creation of a native fistula, i.e., the direct surgical connection between an artery and a vein, which however is not always feasible in all patients (e.g. elderly, diabetics, patients with high Body Mass Index), and usually takes 6-8 weeks Read more about Clinical Problem<\/span>[…]<\/a><\/p>\n","protected":false},"author":6,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"_links":{"self":[{"href":"https:\/\/www.silkelastograft.polimi.it\/index.php?rest_route=\/wp\/v2\/pages\/210"}],"collection":[{"href":"https:\/\/www.silkelastograft.polimi.it\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.silkelastograft.polimi.it\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.silkelastograft.polimi.it\/index.php?rest_route=\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/www.silkelastograft.polimi.it\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=210"}],"version-history":[{"count":3,"href":"https:\/\/www.silkelastograft.polimi.it\/index.php?rest_route=\/wp\/v2\/pages\/210\/revisions"}],"predecessor-version":[{"id":289,"href":"https:\/\/www.silkelastograft.polimi.it\/index.php?rest_route=\/wp\/v2\/pages\/210\/revisions\/289"}],"wp:attachment":[{"href":"https:\/\/www.silkelastograft.polimi.it\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=210"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}