The Application of Split-Thickness Skin Graft as an Autogenous Arterial Conduit in a Goat (Capra Hircus) Model

Abstract

Adequate autogenous vein is often the limiting factor in achieving a successful infrainguinal bypass. Attempts have been made to find alternative conduits; however, these alternatives have demonstrated inferior patency rates. We attempt to show that a split-thickness skin graft conduit provides a feasible autogenous arterial conduit. Neoconduits were prepared with an autogenous split-thickness skin graft (STSG) tubularized for a length of 5-6 centimeters with an appropriate caliber match to native artery. The deep dermal side of the graft was randomized to form either the external surface or the luminal surface. The neoconduit was placed as an interposition graft in the left common carotid artery. Grafts were studied in vivo with duplex ultrasonography and ex vivo by histopathology and immunohistochemistry. Feasibility study involved 4 animals with grafts harvested for study at 24 hours (n= 2) and 7 days (n= 2). Two subsequent groups were studied to evaluate 3-month (n= 8) and 6-month (n= 5) patency. All grafts (n= 4) in the feasibility phase of the study were patent at the time of harvest without evidence of aneurysmal degeneration. In the subsequent 8 goats, grafts with the deep dermal side forming the extraluminal surface (n= 4) had a propensity to ulcerate and rupture or to become aneurysmal (75%). The patency rate of these grafts at 6 weeks was 25%. In contrast, grafts with the deep dermal side forming the intraluminal surface (n= 4) demonstrated 75% patency at 6 weeks. Because of these results the remaining goats underwent placement of neoconduits with the deep dermal side forming the luminal surface. These grafts maintained a patency rate of 80% at 6 months. Neoconduits implanted with a diameter greater than 1.5 times the native arterial diameter became aneurysmal. Histopathology demonstrated neointimal formation in all grafts patent for longer than 7 days. Immunohistochemical staining for Factor VIII/von Willebrand’s factor (vWF) was reactive in the endoluminal cells of these grafts. Immunohistochemical staining for a-smooth muscle actin demonstrated reactivity in conduits patent for greater than 1 month. Split-thickness skin may provide a feasible source for autogenous conduit in arterial reconstructions and warrants further study. Technical factors affecting patency include orientation of the deep dermal surface of the STSG and the diameter of the neoconduit at the time of implantation.