RIGHT RENAL VEIN ELONGATION WITH THE INFERIOR VENA CAVA FOR CADAVERIC KIDNEY TRANSPLANTS . AN OLD NEGLECTED SURGICAL APPROACH

Introduction: Short right renal vein is a frequent and well-known technical inconvenience that is commonly observed during transplantation of the right kidney. We present our experience with the elongation of short cadaveric right renal veins using the contiguous vena cava during cadaveric renal transplants. Methods: We performed 34 kidney transplantations with a short right renal vein requiring elongation using the inferior vena cava, to make the venous anastomosis technically feasible. The elongated right renal vein was anastomosed end to side to the external iliac vein in 24 patients, to the common iliac vein in 8 patients and to the inferior vena cava in 2 patients. The right renal artery with an aortic patch was implanted end to side in 33 patients, and end to end without aortic patch to the internal iliac artery in one patient. Results: In all cases, the vascular anastomoses were easily performed in the recipient and no thrombosis was observed. Conclusion: Elongation of a short right renal vein with the inferior vena cava is a feasible mean to overcome technical problems that may compromise the results of cadaveric renal transplantation.


INTRODUCTION
A short right renal vein (SRRV) is a frequent and well-known technical inconvenience, which is commonly observed during transplantation of the right kidney (1,2).A short or damaged right renal vein can make renal transplantation very difficult (3)(4)(5)(6).The right renal hilum has a single long artery and a short vein that causes difficulties while performing venous anastomosis either from living or cadaveric kidney transplantation, and especially when the right renal artery has an aortic path in the case of a cadaveric donor.It is more complicated and takes more time to perform the transplant especially in either deep iliac vessels, or in the obese or in both.Anastomosis of a SRRV to the common or external iliac vein has been reported to be associated with technical problems such as angulation or tension of the venous anastomosis, reduced mobility, limited placement and inspection of the graft for hemostasis, and possible kinking of the donor artery.One technical solution consists of a more extensive mobilization of the recipient's ves-sels, with the increased risk of lymphocele formation.A number of surgical approaches have been described to solve the problem of a SRRV (5).

MATERIALS AND METHODS
From 1991 to 1997, we performed 243 consecutive cadaveric renal transplants in 243 patients at end-stage end chronic renal insufficiency.This protocol was approved by the local Ethics Commit-tee (# 1111/02).The right kidney was used in 138 patients and from those, 34 kidneys had a very short renal vein requiring elongation using the vena cava to make the venous anastomosis technically feasible and to avoid kinking of renal arteries.From these 34 patients who received the kidney with a very short renal vein, the mean age was 39.4 years (17 -56 years), and there were 19 males (55.9%) and 15 females (44.11%).
A technique used for procurement of cadaveric kidneys is removing the entire block.It was modified from Taylor et al. (9) and Chopin et al. (11).After removing the kidneys as an entire block, on a bench surgery, the left renal vein is divided at its origin on the vena cava and an entire segment of vena cava is left attached to the right renal vein.In 34 grafts with very short right renal vein, the segment of the vena cava below the ostium of the right renal vein was bent up to the level of the renal vein.The segment above the ostium and the excess of the bent-up lower segment were cut off.A running 5-0 monofilament polypropylene thread suture was used to close the upper defect in the vena cava.With this technique we obtained an extended renal vein.The lower segment of vena cava of the right renal vein was left as well as the length of the renal artery, and its excess was cut off.The aorta artery is split in the midline, leaving each half attached to the renal arteries of each kidney (Figures-1 to 3).

Figure 1 -Folding longitudinal split aorta and separation of cadaveric kidneys leaving vena cava intact attached to the right renal vein. RK = right kidney, LK = left kidney, A = aorta, VC = vena cava, LRV = left renal vein.
During renal transplantation an end-to-side anastomosis is performed between the ostium of the segment of vena cava and the recipient's external iliac vein or other vein (Figures -4 and 5).
In our study, we performed 34 transplants of the right kidney, 10 of which had 2 or more arteries attached to a single aortic patch, and 24 had a single artery.In 33 cases we used an aortic patch attached to the renal artery to perform the anastomosis.
From these 34 kidneys transplanted, the elongated right renal vein anastomosis was performed end to side to the external iliac vein in 24 cases, to the common iliac vein in 8 cases, and to the inferior vena cava in 2 cases.The right renal artery anastomosis was performed end to side using the aortic patch at-tached to the renal artery in 21 cases in the external iliac artery, in 10 cases in the common iliac artery, and in 2 cases in the aorta.End to end without aortic patch to the internal iliac artery was used in 1 case.

RESULTS
In all cases mentioned the vascular anastomoses were easily performed and no vascular throm-   bosis occurred.We have been following the progress of these 34 patients, which received cadaveric renal transplant with right renal vein extension, for more than 5 years.Eight patients lost their grafts from chronic rejection and 5 died from others medical complications (heart attack, malignant disease and infections) not related to the surgical approach.

COMMENTS
Technical complications associated with the venous anastomosis have been reported in 1 to 18% of all renal transplants (2)(3)(4)(5)10,11).These problems usually are related to trauma sustained during graft nephrectomy or transplantation.Difficulties are more likely to occur with the right kidney, since the right renal vein is shorter and anatomical variations are more frequent than on the left side (5,12).
Janschek et al. (5) found the average length of the right renal vein to be almost one-half of the artery's length (A/V mean ratio 1.8) in 119 unselected formalin-preserved white adult cadavers, 58 were men and 61 women.Short vessels can consume more time and extend the length of the warm ischemia during renal vessel anastomoses.In renal transplantation, when the vein is slightly longer than the corresponding artery, it allows easier venous and arterial anastomoses.Renal vein thrombosis is a serious complication leading to graft nephrectomy in many cases, despite medical or surgical therapy (5,6).In addition to this risk, there is concern that continuous thrombosis to recipient vein may lead to pulmonary embolus (5,10,11).
Attempts to join a renal vein of inadequate length to the iliac vein are likely to result in an anastomosis that is angulated or under tension.Extensive mobilization of the external iliac vein, to gain additional length, or dissection of the internal iliac vein to use end to end with the renal vein, may increase the likelihood of lymphocele formation because of unnecessary dissection and injury to lymphatics.These technical problems may lead to venous hemorrhage or thrombosis.Right renal vein elongation with the inferior vena cava seems to be a much better approach than venous saphenous autograft, spiral gonadal vein, bovine arterial heterograft and a vascular prosthesis, have been used for these surgical challenges (5)(6)(7)(8)13,14).
Dissection of the hilum of the donor kidney to lengthen the right renal vein is not recommended due the risk of parenchyma hemorrhage and injury of the blood supply of the pelvis and ureter and consequently can cause necrosis to both.Faulty surgical techniques maybe the cause for the majority of late ureteral stenosis, due to ureteral devascularization and ischemia, which could cause delayed ureteral fibrosis (3).
Right renal vein extension by transverse closure of the transected inferior vena cava solves the problem of the short right renal vein in cadaver kidney transplantation (1,9,11).
Right renal vein extension is particularly important in kidneys with multiple vessels, in order to avoid lesions to these venous and arterial variations (11).Due to complicated embryological development, variations in renal vessels show extensive variability, from 12 to 25%.These vessel anatomical variations are more frequent on the right side than on the left side (3,8,12).Right renal vein extension allows an easier anastomosis and possibly better positioning of the kidney (13,14).In our experience 10 of 34 right cadaveric kidneys had two or more arteries.
Benedetti et al. (1994) ( 13) showed in their study that the use of a vein extension had an impact on the outcome.Three hundred and five cadaver transplant recipients received a right kidney.Of these, 76 received a graft with vein extension.None of the 76 experienced technical vascular complications, however 5 of the 229 (2.2%) without vein extension did.There was no difference in the survival of the kidney grafts with or without extension in follow up 1 to 2 years after transplantation.The authors concluded that there is no increased risk with the use of the vena cava extension and recommend that the donor team routinely provide the right kidney with the vena cava attached.This allows the recipient team to determine whether an extension is appropriate for the particular recipient.Elongation of the right renal vein with the vena cava is a feasible and physiological procedure and does not interfere with multiorgan procurement.No vascular complications were encountered.No other techniques were required.We recommend removal of the entire segment of vena cava during cadaveric kidney harvesting.
This technique eliminates the need to mobilize the recipient's vessels by a more extensive dissection, and the internal iliac vein division is not required.The kidney graft can easily be placed above the iliac vessels.This technique also preserves a patch of cadaveric aortic wall along with the right renal artery, thereby minimizing the risk of arterial graft kinking, renal transplant artery stenosis and thrombosis.
When the recipient has extensive iliac and inferior cava venous disease, longer vein conduits can also be used to reach patent veins to drain the venous blood from the kidney graft, or perform orthotopic renal transplantation (28,29).In some cases, it can be drained to the superior mesenteric (30), portal, splenic, subclavian veins or directly to the right atrium of the heart.
Some times the short right renal vein can be repaired or elongated with patch or flap of the inferior vena cava (22).Any others veins can be used as iliac or femoral cryopreserved allografts or from the same cadaver who was the donor of the kidney graft (31)(32)(33)(34).
In conclusion, the elongation of the short right renal vein with the contiguous inferior vena cava is a feasible way to overcome technical problems that may jeopardize the results of cadaveric renal transplant.This procedure allows both kidneys to be taken with the full length of the renal vein and artery with an aortic cuff.The method is most useful when the right renal vein is extremely short or when the recipient has a large abdomen and a deep pelvis or both, also in case of severe disease of the iliac and vena cava veins.

Figure 2 -
Figure 2 -Elongation of the right renal vein with segment of the vena cava.

Figure 3 -
Figure 3 -Bench surgery.Right vein elongated (V), and patch of the aorta (A) attached to 2 renal arteries.

Figure 4 -
Figure 4 -Schematic drawings demonstrating that elongation of the right renal vein avoids kinking of the renal arteries.A = iliac artery of the recipient, V = iliac vein of the recipient, K = kidney.

Figure 5 -
Figure 5 -Intraoperative picture of the right renal vein elongated (white arrow) and anastomosed end-to-side to the external iliac vein (yellow arrow).