Successful treatment of renal artery transplant pseudostenosis: endovascular recanalization and stenting of external iliac artery occlusion

Introduction Vascular problems account for 10 % of the overall structure of renal allotransplantation complications [1]. These include transplant renal artery (TRA) thrombosis, renal vein thrombosis, TRA stenosis, renal vein stenosis, arteriovenous fistulas, and vascular pseudoaneurysms. 75 % of vascular complications are represented by TRA stenosis [1]. One of the reasons for the TRA stenosis formation in the late postoperative period is vascular atherosclerosis [2]. Stenosis most commonly develops in the TRA anastomosis with the external iliac artery (EIA) or in the TRA distal segment, less frequent in the ileorenal segment (in 1.5 % of cases) [3, 4]. When isolated stenosis occurs proximal to the TRA anastomosis with the iliac artery, the so-called TRA pseudostenosis develops [3]. The clinical picture of hemodynamic significant TRA stenosis is characterized by the presence of difficult-to-control arterial hypertension (AH) and/or progressive allograft dysfunction [1, 2]. Timely surgical correction leads to stabilization of blood pressure and renal transplant function. The method of choice for surgical correction is percutaneous endovascular intervention (PEI) with balloon angioplasty and/or stenting of the affected vessel [1, 3, 5]. Clinical case We present a case of a 66-year-old male patient with a history of polycystic kidney disease, frequent attacks of pyelonephritis, and drug-controlled hypertension. Since February 2011, end-stage renal failure developed and was treated with peritoneal dialysis. In June 2011, bilateral nephrectomy was performed, and in November 2011, renal allotransplantation was performed. Transplant function was immediate, creatinine levels remained between 110 and 130 μmol/L for more than 10 years. Since July 2023, swelling of the legs, complaints of weakness in the legs, pain in the right leg when walking, an increase in blood pressure to 180/100 mm Hg on the usual three-component antihypertensive therapy have appeared. In August 2023, creatinine increased to 180 µmol/l, urea - 14.9 mmol/l, daily proteinuria - 0.18 g. The patient admitted with decompensated hypertension and progressive transplant dysfunction. Doppler ultrasound (DUS) of the transplant vessels showed a moderate decrease in peak systolic velocity (PSV) of intraparenchymal blood flow, a change in the spectrum according to the type of poststenotic vasodilation (“tardus et parvus”) - indicators of the arterial resistance index (RI) 0.46-0.58, flow acceleration time 0.15-0.17 ms (Fig. 1A ). The area of anastomosis of the TRA with the EIA was unremarkable. The EIA is visible as a short fragment distal to the anastomosis with retrograde, monophasic, low-resistance blood flow (Fig. 1B ). A hemodynamically significant stenosis of the proximal fragment of the EIA was suggested. DUS of the right lower extremity arteries showed that against the background of multi-level hemodynamically significant atherosclerosis and calcification, collateral filling of the femoral-popliteal arteries, arteries of the lower leg, and dorsum of the foot is determined with a sharp decrease in velocity characteristics (PSV 10-20 cm/sec). Multispiral computed tomographic (CT) angiography was performed. A series of axial sections through the EIA in the arterial phase of contrast-enhanced CT showed the right EIA from the ostium to the TRA origin level with occlusion of the lumen against the background of massive atheromatous lesions (Fig. 2, a, b, c ). The 3D-reconstruction of the arterial phase of contrast-enhanced CT showed that there were right iliac arteries with atherosclerotic lesions of the walls (arrow indicates the occlusion zone), intact TRA (two arrows) (Fig. 1C ). Due to the confirmed critical stenosis of the EIA and clinical and instrumental signs of pseudo-stenosis of the TRA, a decision was made to perform direct angiography followed by PEI. The right femoral artery was punctured retrograde, and an introducer was installed. Retrograde angiography revealed chronic occlusion of the EIA, and an intact TRA was visualized below the occlusion (Fig. 3A ). The right brachial artery was punctured, an introducer was installed, a diagnostic catheter was inserted into the right common iliac artery, and antegrade angiography of the common iliac artery was performed: occlusion of the EIA from the ostium was confirmed and 90% stenosis of the ostium of the internal iliac artery was revealed (Fig. 3B ). A decision was made on retrograde endovascular recanalization of the occluded segment of the EIA. The guidewire was passed through the occlusion into the infrarenal aorta. Predilatation of the EIA stenotic lesion area with a balloon catheter was performed, and the EIA antegrade blood flow was obtained (Fig. 3C ). A peripheral stent was implanted into the area of EIA stenosis, and post-dilatation was performed in the stent with a 10.0 × 60 mm balloon catheter. The control angiogram demonstrated complete restoration of patency of the right EIA and satisfactory antegrade blood flow in the TRA (Fig. 3D ). After recanalization, the patient’s condition improved significantly: blood pressure levels normalized, transplant function was restored (creatinine 111 μmol/l), pain and weakness in the legs disappeared, pulsation appeared in a. dorsalis pedis. Control DUS demonstrated positive dynamics: velocity indicators of intraparenchymal blood flow increased, Doppler signs of post stenotic vasodilation were mitigated. Conclusion The presented clinical case demonstrates a rare variant of TRA pseudo-stenosis, which was caused by progressive multifocal atherosclerosis of the recipient arteries. Occlusion of the EIA resulted in retrograde blood supply to the allograft, its dysfunction, and refractory hypertension. Successful PEI with stenting made it possible to completely restore antegrade blood flow in the EIA occlusion area and normalize the blood supply to the transplant. The PEI resulted in restoration of transplant function, relief of AH and resolution of the symptoms of intermittent claudication. Informed consent was obtained from the patient for publication of clinical information and images.

стеноз почечной артерии трансплантата, атеросклеротическое поражение наружной подвздошной артерии, чрескожное эндоваскулярное вмешательство, баллонная ангиопластика, стентирование, клинический случай, transplant renal artery stenosis, atherosclerotic lesions of the external iliac artery, percutaneous endovascular intervention, balloon angioplasty, stenting, case report

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