Replacement of the Left Common Iliac Vein with a Custom-Made Bovine Pericardium Tubular Graft

Abstract

To date, venous reconstruction has not been as successful as arterial reconstruction. Prosthetic materials used as venous substitutes produce much lower patency rates with a higher incidence of early thrombosis than those used as arterial substitutes.

We describe the case of a 38-year-old obese woman in whom we encountered an unexpected tear of the common iliac vein intraoperatively, during an anterior approach to the lumbar spine. Because of limited options, we replaced the vein with an interposition tubular graft that was custom-made from bovine pericardium. Two years later, the patient remained asymptomatic with a patent graft. To our knowledge, there has been no other reported case in the world medical literature of replacement of medium-sized veins by this technique.

Prosthetic replacement of veins is as yet much less successful than is arterial revascularization. Grafts constructed of synthetic materials often produce poor results when used as venous substitutes, ¹ and smaller peripheral conduits have worse patency rates than their larger central counterparts. ^2,3 Results are best when veins are replaced or bypassed with autologous conduits. ⁴ The greater saphenous vein is generally the conduit of choice. ⁴ We present the case of a patient who had an acute traumatic tear in the left common iliac vein, which occurred intraoperatively during an anterior approach to the lumbar spine. The vein required immediate reconstruction.

Case Report

A 38-year-old obese woman underwent surgery on 23 February 1998 for a chronic lumbosacral strain/sprain syndrome and degenerative disk disease at the L4-L5 level. The lumbar spine was exposed anteriorly with a standard retroperitoneal approach through a left flank incision. The external and internal oblique and the transverse abdominal muscles were split in the direction of their fibers and retracted. The ureter was retracted medially en bloc with the posterior peritoneum and was protected to prevent injury. The distal abdominal aorta and the left iliac vessels were dissected and mobilized, and their respective lumbar arteries and veins were ligated and transected until mobilization and retraction could be achieved without tension. Multiple blades of an Omni retractor (Omni-Tract Surgical, a division of Minnesota Scientific, Inc.; Minneapolis, Minn) were strategically placed for retraction. A diskectomy was performed. The disk space was subsequently dilated with 10- and 12-mm dilators. A double-barreled cannula (Med-tronic Sofamor Danek; Memphis, Tenn) was placed over the disk space, further protecting the surrounding structures. With the guidance of anteroposterior and lateral fluoroscopic images, the space was enlarged to 26 mm. Bone cages filled with bone graft were then placed. The cages measured 18 mm in diameter and 22 mm in depth. They were recessed 3 mm from the anterior edge of the L4-L5 vertebral bodies. The cannula was then removed.

At this point, an accidental tear in the left common iliac vein caused severe bleeding. Finger pressure was applied. The 2-cm longitudinal tear was repaired with 6-0 polypropylene vascular sutures. Because of the patient's obesity and the brisk bleeding, vascular clamps could not be applied without risk of further damage to the vein, the adjacent structures, or both. Therefore, the repair was done with intermittent finger pressure and cell saver suction. At the conclusion of the repair, however, the iliac vein was severely stenotic. It was anticipated that if the stenosis was not corrected, venous thrombosis would occur, possibly with severe venous hypertension of the leg and venous gangrene. We decided to restore venous flow by replacing the damaged segment. A sheath of bovine pericardium (Medtronic, Inc.; Minneapolis, Minn) was rinsed in saline solution 3 times as specified by the manufacturer. The iliac vein caudal to the obstruction was measured with a caliper at 1.2 cm in diameter. A pericardial tube of the same diameter was constructed with an endostapler (Fig. 1) as previously described. ² Now, with a dry field, the inferior vena cava could be dissected and moved to the right of the aorta to allow placement of a vascular clamp. The patient was given 5,000 IU of heparin intravenously. With 6-0 polypropylene continuous sutures, graft anastomoses were performed end-to-end proximally to the terminal portion of the inferior vena cava and then distally to the iliac vein. The vascular clamps were removed, and excellent flow began immediately, as confirmed by intraoperative Doppler analysis. A Jackson Pratt catheter with a closed suction system (C.R. Bard, Inc.; Murray Hill, NJ) was placed adjacent to the repair before closure. A continuous heparin infusion was maintained postoperatively until the 2nd postoperative day, when it was changed to warfarin. The patient's leg remained free of pain, edema, cyanosis, and paresthesias at all times. Bleeding was minimal, and there was no retroperitoneal hematoma formation despite anticoagulation. The warfarin was discontinued 6 months postoperatively. Eighteen months postoperatively, a venous duplex scan of the lower extremities revealed no abnormalities (Fig. 2). Two years after surgery, the patient remained asymptomatic.

Fig. 1 Intraoperative construction of the custom-made pericardial xenograft. The pericardium can easily be tailored to specific measurements. The double line of vascular staples provides rigidity, secures the orientation, and simplifies handling. The shiny surface of the pericardium is always placed toward the lumen.

Fig. 2 Doppler imaging of the external iliac vein demonstrates normal lumen and flow. Valsalva maneuvers produced a normal increase in lumen diameter of the vein and cessation of flow that returned quickly on expiration. Collateral circulation was not seen. All deep veins of the leg had normal spontaneity, phasicity, and augmentation. Their compressibility was complete. There were no intraluminal defects.

Discussion

No uniform criteria have been developed to establish what type of material is best for the replacement of veins; the ideal venous conduit has yet to be developed. The choice of graft material depends on the circumstances, as well as the preference and personal experience of the surgeon; an autologous saphenous vein is generally preferred. In this patient, however, harvesting of the saphenous vein was prevented by her position on the operating table. A change of position, along with her marked obesity, would have put her at risk of bacterial contamination. Preparation and draping of the leg and groin would have delayed restoration of venous flow, risking venous thrombosis or compartment syndrome. An autologous saphenous vein interposition graft would have been stenotic, reducing the diameter of the common iliac vein by approximately 50%, and creation of a spiral graft with the saphenous vein would have prolonged the venous occlusion time further. The bovine pericardial graft was immediately available, and its preparation—including rinsing and construction with the stapler—took less than 15 minutes.

The patency and durability of bovine pericardium has been reported in the superior vena cava, ⁵ the inferior vena cava, ⁶ and the pulmonary artery, ⁷ in both experimental and clinical settings. The technique presented herein has previously been described for use in reconstruction of the superior vena cava. ⁵ Bovine pericardium is advantageous over autologous pericardium in that it is readily available for replacement of veins, both in the chest and in the abdomen. In this case, we were able to customize the bovine pericardium to the precise diameter of the recipient vessel (Fig. 1). Because bovine pericardium is firmer and therefore easier to sew than is autologous graft, ⁷ its use saved time during surgery. Although we did not know of any previous case in which this graft had been used to replace smaller caliber vessels such as the iliac vein, it appeared to be the best alternative for our patient on the basis of our previous experience. ^1,5,6

We conclude that further evaluation of this graft is warranted. To our knowledge, successful replacement of a medium-sized vein with a tubular graft of bovine pericardium has not been previously reported in the world medical literature.