External Biodegradable Supporting Conduit Protects Endothelium in Vein Graft in Arterial Interposition

Abstract

The prevention of circumferential distension could reduce structural damage in arteriovenous grafts. We studied the effect of an external biodegradable supporting conduit on the endothelium and extracellular matrix in vein graft in a pig model. Cephalic vein control grafts (Group I) and jugular veins wrapped in a vicryl mesh tube (I.D. 4 mm) (Group II) were implanted into autologous carotid arteries (n = 14). The grafts were explanted after 1 and 24 hours and at 1 and 3 weeks and evaluated by ELISA for endothelial DNA synthesis and by immunohistoenzymic assays for cells and extracellular matrix. In group I an initial loss of endothelial and smooth muscle cells along with elastin breakdown was followed by an impaired endothelial regeneration and significant graft wall thickening. The elastic tissue was replaced by collagen type I and chondroitin sulfate accumulations, which included a disarray of alpha-smooth muscle actin positive cells. The endothelium was preserved in group II. After 3 weeks the circumferential elastin layers were densified, distended and separated from the endothelium by a neointimal growth of irregular thickness. Biodegradable perivenous conduit minimized endothelial injury and allowed the partial preservation of elastin fibers and smooth muscle cells in the arteriovenous graft. It did not however, prevent myofibroblastic cell proliferation and triggered a macrophagic reaction.

Does PGA external stenting reduce compliance mismatch in venous grafts?

“…Numerous reports indicate that thickening happens during the remodeling process in grafts both with and without protection [13,15]. This study showed consistent results (see Figure 5); the wall of the grafts was much thicker than that of the vein (there was a significant statistical difference between HV and HSM/HM).…”

“…It has been shown that this protection could preserve the endothelium cells (ECs), smooth muscle cells (SMCs) and elastic fibers and increase vasa vasorum [12,13]. It also indicates that the ES can decrease wall thickness and matrix deposition significantly [13-15], prevent atherosclerosis around the anastomosis [16-20] even in hypercholesterolemic animals [15], and reduce cell apoptosis [3,7,21,22]. Moreover, ES can not only improve the patency of the normal vein graft, but also means that varicose and dilated veins can be used [23,24].…”

Inhibition of Accelerated Atherosclerosis in Vein Grafts by Placement of External Stent in ApoE*3-Leiden Transgenic Mice

“…This has been described previously in a pig vein graft model in which an external biodegradable supporting conduit protected the endothelium in vein grafts. 26 In unstented vein grafts, SMC loss was observed during the first week after surgery. This is in accordance with SMC loss described in specimens of early vein graft in patients 10 and in various experimental studies.…”

Perivenous Application of Fibrin Glue as External Support Enhanced Adventitial Adenovirus Transfection in Rabbit Model

“…Therefore, many procedures have been adopted to reduce neointima formation through lowering the wall tension of veins. It has been established that a bioabsorbable, nonrestrictive, external sheath could inhibit vein graft thickening in animal and human experiments [3,11]. However, these external stents have the risk of injury to the vein wall and might be limited by side to side anastomoses.…”