after the procedure and equalize at 4 weeks. The authors agree that the data may differ if alternate laser wavelengths are compared versus radiofrequency ablation, such as the newer 1,319-, 1,320-, and 1,470-nm wavelengths. However, the proto- cols for use of these wavelengths use lower energy densities (ie, dosages). If Dr. Lewis is a champion of another laser, he is free to conduct a study modeled after our work. Finally, as is customary, a courtesy copy of the manuscript was provided to VNUS Medical. It should be made clear that the authors do not participate in the advertising practices of the radiofrequency equipment manufacturer or JVIR. Jose I. Almeida, MD, RVT John Kaufman, MD Oliver Go ¨ckeritz, MD Paramjit Chopra, MD Martin T. Evans, MD Daniel F. Hoheim, MD Raymond G. Makhoul, MD Tim Richards, MD Christian Wenzel, MD, and Jeffrey K. Raines, PhD, RVT Miami Vein Center (J.I.A., J.K.R.) 1501 S. Miami Ave. Miami, FL 33129; Dotter Interventional Institute (J.K.) Oregon Health and Science University Portland, Oregon; Venenzentrum Elsterpark (O.G., C.W.) Leipzig, Germany; Midwest Institute for Minimally Invasive Therapies (P.C.) Melrose Park, Illinois; Vein Solutions (M.T.E., R.G.M.) Richmond, Virginia; and Community Surgical Associates (D.F.H., T.R.) Missoula, Montana Early Postoperative Renal Vein Stenosis after Renal Transplantation: A Report of Two Cases From: James Pine, MBChB, MRCS, Rajasundarum Rajaganeshan, MD, MRCS, Richard Baker, MA, PhD, MRCP, Andrew Lewington, MD, FRCP, Jai Patel, MBChB, MRCP, FRCR, Krishna Menon, MBBS, MS, FRCS, David Kessel, MBBS, MRCP, FRCR, and Niaz Ahmad, MBBS, MD, FRCS Departments of Transplant Surgery (J.P., R.R., K.M., N.A.) Nephrology (R.B., A.L.), and Vascular Radiology (J.P., D.K.), St. James’s University Hospital Leeds, LS9 7TF, United Kingdom Editor: Vascular problems, such as renal artery stenosis or renal vein thrombosis, are well recognized complications follow- ing renal transplantation. Interventional radiologic tech- niques are often used as diagnostic tools and as therapeutic options to prevent graft dysfunction (1). Renal vein stenosis is a rare vascular complication following renal transplanta- tion. It usually occurs in the early postoperative stages, often as a consequence of malpositioning of the vein or extrinsic compression (2). Occasionally, renal vein stenosis may be pre-existing in the donor and remain unrecognized until after transplantation. Herein, we report two cases of early renal vein stenosis in the transplanted kidney that were successfully managed by using metallic self-expanding vas- cular stents. The institutional review board at our institution does not require approval for this type of project. The first case involves a 28-year-old man with end-stage renal failure secondary to familial glomerulonephritis who received a 2-2-2 HLA mismatched non-heart-beating donor (NHBD) kidney from an 18-year-old donor. At postopera- tive day 3, the patient underwent Doppler ultrasonography (US) due to worsening renal function. The findings at US were suggestive of a patent renal artery and high-velocity flow (200 cm/s) in the main renal vein, which are indicative of renal vein stenosis. Findings at magnetic resonance (MR) angiography were suggestive of renal vein stenosis. There was no evidence of extrinsic venous compression. A formal venogram demonstrated a long stricture of the transplant renal vein beyond the anastomosis (Figure, a). There were dilated collateral vessels around the renal hilum suggestive of a chronic obstruction. A self-expanding metal stent (40  8 mm; Cordis, Miami, Florida) was inserted, resulting in a marked improvement in flow (Figure, b). Following the procedure, the patient received intravenous heparin for an- ticoagulation. Warfarin was initiated to maintain an inter- national normalized ratio in the range of 2–3 for 6 months. Creatinine levels continued to decrease after the procedure. A follow-up US scan revealed a healthy transplanted kid- ney. The creatinine level remains stable at 1.30 mg/dL (115 mol/L) 2 years after transplantation. The second case involves a 30-year-old woman with end-stage renal failure secondary to chronic glomerulo- nephritis and a history of hepatitis B infection who re- ceived a NHBD kidney from an 11-year-old donor. Post- operatively, the graft exhibited delayed function. A US scan obtained on day 8 demonstrated little or no perfusion of the upper pole of the transplanted kidney, absent end- diastolic flow within the interlobar arteries in the lower pole, and multiphasic flow in the renal artery. The main renal vein was of a reduced caliber and contained high- velocity flow (140 cm/s). An MR angiogram/MR venogram showed that, distal to the anastomosis, the main renal vein was narrowed along its entire length. A venogram revealed multiple stenoses involving the main vein and segmental branches (Figure, c). Collateral veins were seen extending down the ureter. Angioplasty to 4 mm of the main renal vein was performed with good result except for a short area of residual stenosis requiring the deployment of a small racer stent (18  5 mm; Medtronic, Minneapolis, Minnesota). A good angio- graphic result was achieved (Figure, d). The patient re- ceived intravenous heparin for anticoagulation. On day 12, the patient had a retroperitoneal bleed requiring blood transfusion. CT angiography helped confirm bleeding from a lumbar artery, which was successfully embolized angiographically. It was decided to anticoagulate with aspirin and clopidogrel. Follow-up US revealed no further problems. The patient’s renal function continued to im- prove, and 6 months after transplantation her creatinine level is 1.24 mg/dL (110 mol/L). None of the authors have identified a conflict of interest. DOI: 10.1016/j.jvir.2009.10.023 Letters to the Editor • 303 Volume 21 Number 2