JOURNAL OF SURGICAL RESEARCH 36, 306-3 11 (1984) Venous Prostheses: Improved Patency with External Stents ROBERT J. ROBISON, M.D., PAMELA S. BEIGH, M.D., ANDREW C. FIORE, WILLIAM P. DESCHNER, M.D., NICHOLAS J. SEARS, M.D., J. STEVEN WHITAKER, HAROLD KING, M.D., AND JOHN W. BROWN, M.D.’ Department of Surgery, Section of Cardiothoracic Surgery, Indiana University Medical Center, Indianapolis, Indiana 44223 Presented at the Annual Meeting of the Association for Academic Surgery, Syracuse, New York, November 2-5, 1983 A uniformly successful prosthesis for replacement in the venous system has not been developed. This study assesses the effect of external stents on the patency of polytetrafluoroethylene (PTPE) grafts in the infrarenal vena cava. Under general anesthesia, 2 I mongrel dogs underwent midline laparotomy. The infrarenal vena cava was resected and replaced by a standard segment (8 cm X 10 mm) of stented PTPE (12 dogs) and nonstented PTFE (9 dogs). Patency was assessed by contrast venography and the results compared between the two groups. The 7-, 30-, and 90&y patency was 12/12, 10/12, and 9/12, respectively, for stented PTPE and 6/9, 2/9, and 2/9, respectively, for nonstented PTPE. The patency of externally stented PTFE at 30 and 90 days was significantly better than grafts fashioned from PTPE alone (P < 0.05 by chi-square analysis). These data demonstrate that external stenting improves the early patency of PTFE prostheses in the infrarenal vena cava. Consideration should bc given to the clinical use of externally stented PTPE when prosthetic replacement in the venous system is required. INTRODUCTION A consistently successful prosthesis for the replacement in the venous system, unlike the arterial system, has not as yet emerged [2, 3, 8, 14, 21, 251. Failure of prosthetic grafts has been attributed to the phasic venous flow and external graft compression.The useof external graft support with stents [ 171 and a throm- boresistant luminal surface of PTFE [23] have been suggested as methods to improve graft patency. Using a canine model, Fiore et al. [6] demonstrated that externally stentcd PTFE achieved a patency rate equal to autologous vein as a thoracic caval substitute. The in- frarenal vena cava, because of its lower flow and positive intraabdominal pressure, has proved to be a stringent test for venous sub- stitutes. The purpose of this study was to (1) assess the effect of external stenting on the patency of PTFE (Gore-Tex’) grafts, and (2) ’ Author to whom requests for reprints should bc ad- dressed * Gore-Tex is a registered trademark of the W. L. Gore and Associates, Inc. in Elkton, Maryland. determine if graft patency could be achieved in the difficult infrarenal vena cava position. METHODS Twenty-one mongrel dogs ( 18-22 kg) were anesthetized with intravenous thiopental so- dium (25 mg/kg) and mechanically ventilated with oxygen and halothane through an en- dotracheal tube. The infrarenal vena cava was exposedthrough a midline abdominal incision and isolated from the renal veins superiorly to the confluence of the common iliac veins inferiorly. The lumbar and right gonadal veins were ligated. After systemic heparinization (1.5 mg/kg) occluding clamps were applied. The infrarenal vena cava was resected and replaced with a standard segment ( 10 mm X 8 cm) of externally stented PTFE in 12 dogs and non- stented PTFE in 9 dogs (Figs. 1, 2). Prophy- lactic antibiotics (cefamandole) were given prior to the procedure and for 5 days post- operatively. No postoperative anticoagulants or antiplatelet agents were used. The PTFE pore size was 30 pm in both groups. 0022-4804/84 !§ 1.50 Copyright 0 1984 by Academic Press, Inc. All ri&u of reproduction in any form resewed. 306