For renal transplantation, the standard venous drainage of the allograft is via the iliac vein. In unusual circumstances, such as thrombosis or agenesis of the iliac veins and the inferior vena cava, portal venous drainage may be a suitable option. We report a case in which the inferior mesenteric vein was used for venous drainage of a cadaveric renal allograft.
A. is a 46-year-old female patient with renal failure secondary to hypertensive nephrosclerosis. She had been maintained on hemodialysis for 6 years prior to transplantation. Her past medical history was notable for multiple episodes of deep venous thromboses and thromboses of multiple dialysis accesses, for which she was treated with chronic anticoagulation (warfarin sodium). She had also undergone placement of an inferior vena cava (IVC) filter because of bleeding complications secondary to over-anticoagulation. An inferior vena cavagram (Figure 1) performed 3 months prior to transplantation showed chronic occlusion of the common iliac veins and infrarenal IVC. Venous drainage of the lower extremities was maintained via multiple retroperitoneal collateral veins and the ascending lumbar vein (Figure 1).
The patient underwent transplantation with a 0-mismatched cadaveric renal allograft. The donor kidney was a right kidney with 2 renal veins on a full vena cava and 2 renal arteries on a common aortic patch. Intraoperatively, she was noted to have thrombosis of the IVC to the level of the filter and both common and external iliac veins. Consequently the mesenteric venous system was explored, and both the superior mesenteric and inferior mesenteric veins were noted to be dilated and suitable for venous drainage of the allograft. An end-to-side anastomosis was constructed between one renal vein and the IMV using #7–0 polypropylene sutures (Figure 2). The donor common aortic patch was anastomosed end-to-side to the recipient right common iliac artery with #6–0 polypropylene suture. A standard ureteroneocystostomy was performed over a ureteral stent.
The patient received induction immunosuppression consisting of basiliximab and steroids. She had immediate function of the allograft and was discharged 6 days following surgery. Currently, 6 months postoperatively, her serum creatinine is 0.6 mg/dL on maintenance immunosuppression consisting of tacrolimus, mycophenolate mofetil and prednisone. A recently performed magnetic resonance angiogram demonstrated the graft vasculature (Figure 3).
Iliac vessels are the most common site for renal graft revascularization. However, in certain situations, either for anatomic reasons, or because of previous transplants or prior surgeries, it may be necessary to use alternate sites for vascular reconstruction. Venous drainage into the infrarenal IVC is an initial option when both iliac veins are unsuitable. In the setting of IVC thrombosis and patent iliac veins, the iliac system can still be used if venous pressures are below 25 mmHg (1, 2). Another option is the use of the suprarenal IVC or the use of the native renal vein following native nephrectomy (3). Others have previously described the use of the portal venous system for renal allograft revascularization in the setting of iliocaval thrombosis. Rosenthal and Loo reported using the IMV for this purpose, and Aguirrezabalaga et al. recently described the use of the superior mesenteric vein (SMV) (4, 5).
In the present case, drainage via the iliac veins was not an option because of complete thrombosis. The patient was receiving hemodialysis through a tunneled, left transfemoral catheter (her only remaining dialysis access) that was positioned at the IVC/right atrial junction. Moreover, the IVC was completely occluded to the level of the IVC filter, which had been placed adjacent to the native renal veins, making venous drainage to the infrarenal IVC or native renal veins impossible. Additionally, the presence of the dialysis catheter within the suprarenal IVC made partial occlusion of the IVC at this level unfeasible. Since this catheter was the patient's only remaining dialysis access, removal of the catheter to facilitate venous anastomosis was also not an option. Therefore, in our opinion, anastomosis to the suprarenal vena cava was also not practicable.
Portal venous drainage provided an alternate route in this patient. Consideration was given to using the technique described by Aguirrezabalaga et al. of anastomosis to the SMV; however, several factors precluded this approach. Firstly, since the donor kidney was a right kidney, the alignment of the two veins and IVC (donor) did not provide for a suitably long venous segment for direct anastomosis to the SMV. Secondly, by maintaining the two renal arteries on a common aortic patch, we were unable to use a donor arterial conduit as an extension graft as would be required when placing the kidney in the right orthotopic location.
In this patient, selection of the IMV for venous drainage enabled us to overcome these issues. First, we exposed the entire retroperitoneum by extensively mobilizing the root of the small bowel mesentery and right colon (Cattell-Braasch exposure). This facilitated exploration of the great vessels and retroperitonealization of the graft after implantation. Additionally, since the IMV is a small caliber vessel, which is relatively fixed in the colonic mesentery, short donor vessels require placement of the allograft near the IMV. Consequently we removed the donor IVC and based the entire venous drainage of the allograft on one of the renal veins. Moreover, due to this short distance and relative proximity to the IMV, the arterial anastomosis was constructed to the right common iliac artery. Finally, in contrast to our standard anastomotic technique, we elected to perform the arterial anastomosis before the venous so as not to cause excessive mobilization on the anastomosis to the thin-walled IMV.
Although we were successful in this case, several features related to the IMV may preclude its use for renal allograft venous drainage. The small caliber of the IMV is likely to pose an excessive risk of thrombosis. Donor venous anatomy, specifically the size and number of renal veins, may also pose additional technical challenges. Since the IMV is a relatively thin-walled vein, anastomosis to a long venous segment (such as a vena caval conduit) may be more problematic as a result of the greater number of sutures that need to be placed. Because of this concern, we removed the donor IVC and based our entire venous drainage on one of the renal veins. Given that the renal veins anastomose freely within the kidney, venous drainage can occasionally be based on a single renal vein. In general, the largest diameter vein should be selected in order to maximize venous drainage.
In cases of anomalies or thrombosis of the iliocaval venous system, the portal venous system may provide a suitable option for venous drainage of the renal allograft. Consideration of both recipient and donor anatomy is required to select the best option for venous drainage.