Endovascular abdominal aortic stenosis treatment alleviates renal failure after kidney transplantation

Abstract

A 79-year-old man developed bilateral intermittent claudication. Peritoneal dialysis had been initiated at 55 years of age to manage chronic renal failure. In addition, he underwent kidney transplantation at 61 years of age. His Ankle-Brachial Index (ABI) was 0.82 and 0.71 for the right leg and left leg, respectively. Furthermore, his serum creatinine level had increased from 0.98 mg/dL to 2.38 mg/dL over the past 2 years. CT angiography revealed focal calcified stenosis in the terminal abdominal aorta. However, ultrasound revealed no significant stenotic lesion in the supplied artery bound to the transplanted kidney from the right external iliac artery. We performed endovascular therapy for abdominal aortic stenosis using the pressure gradient. Following the procedure, the patient’s symptoms disappeared and the ABI increased to 1.25 and 1.14 in the right leg and left leg, respectively. Furthermore, the serum creatinine level improved to 0.96 mg/dL.

Background

Peripheral artery disease is common in patients after kidney transplantation.¹ Moreover, long-term immunosuppressant therapy reportedly causes metabolic abnormalities, such as dyslipidaemia, hyperglycaemic and atherosclerosis.^{2 3} Atherosclerotic disease of the terminal aorta, concomitant with renal failure, is rare following kidney transplantation; however, it can occur because of a reduction in the flow of blood from the aorta to the transplanted kidney. In this report, we present the case of a patient with renal failure resulting from abdominal aortic stenosis after kidney transplantation, in which endovascular therapy (EVT) successfully improved renal function.

Case presentation

A 79-year-old male patient was referred to our hospital with bilateral intermittent claudication and renal failure. His medical history included hypertension, dyslipidaemia and diabetes mellitus. At age 55 years of age, he began peritoneal dialysis for the management of chronic renal failure. In addition, he underwent kidney transplantation 6 years later. After surgery, maintenance doses of prednisolone (4 mg/day) and Neoral (100 mg/day) were administered.

Investigations

His systolic blood pressure was controlled less than 140 mm Hg and his urine output did not change in last 2 years. The patient’s Ankle-Brachial Index (ABI) was 0.82 and 0.71 for the right leg and left leg, respectively, at the time of referral. Blood tests indicated an increase in serum creatinine levels from 0.98 mg/dL to 2.38 mg/dL over the past 2 years. One year ago, serum creatine level was 0.99 mg/dL, 1.12 mg/dL 6 months ago and 1.99 mg/dL 1 month ago. CT angiography revealed focal calcified stenosis in the terminal abdominal aorta (figure 1A and B). Nonetheless, ultrasound revealed no significant stenotic lesion in the supply artery bound to the transplanted kidney from the right external iliac artery. Doppler echo findings showed that his peak systolic velocity was 300 cm/s and Resistive Index was 0.73, indicating a possibility for improvement of his creatine clearance.

Figure 1.

CT. (A) The arrow shows calcification of the terminal aorta to the bilateral iliac arteries in the coronal CT image. (B) The axial CT image shows the circumferential calcified stenosis in the terminal abdominal aorta.

Treatment

Following a puncture of the patient’s right common femoral artery, a 6 Fr sheath (Terumo Corporation, Tokyo, Japan) was inserted. We crossed the calcified stenotic lesions in the terminal abdominal aorta (figure 2A) with a 0.035-inch guidewire (Terumo Corporation, Tokyo, Japan), and a straight catheter passed through. Intravenous ultrasound (IVUS) (Eagle Eye Platinum, Volcano Corporation, Amsterdam, the Netherlands) indicated circumferential calcification at the stenotic site (figure 2B). We checked the pressure gradient (PG) at the site using a 4 Fr straight catheter and found it to be 73 mm Hg (figure 2C, between I and II). Therefore, we performed EVT at the stenosis site (figure 2A(b)). Following dilatation using an 8.0/40 mm balloon (SABER X, Cordis, Tokyo, Japan), we implanted a self-expandable stent (14.0/40 mm, E-Luminexx, Bard, Salt Lake, USA) at the site. A semi-compliant balloon (10.0/40 mm, Sterling OTW, Boston Scientific, Massachusetts, USA) was used for post-dilation. The final angiography revealed favourable blood flow with perioperative complications (figure 3A). IVUS showed expansion of the stent at the stenosis site (figure 3B). Moreover, the PG had decreased to 6 mm Hg (figure 3C).

Figure 2.

(A) The angiography shows a calcified stenotic lesion in the terminal aorta. (B) Intravenous ultrasound (IVUS). The blue labelled (a), (b) and (c) indicate the IVUS findings from the angiography in figure 2A. (C) Pressure gradient (PG). PG was measured with a 4 Fr straight catheter. PG was 73 mm Hg between lesions Ⅰ and Ⅱ. The PG between lesions Ⅱ and Ⅳ was 3 mm Hg.

Figure 3.

(A) The final angiography shows acceptable flow from the abdominal aorta to the iliac artery. (B) The blue labelled (a) shows intravenous ultrasound findings from the angiography of figure 3A(a). (C) Pressure gradient (PG) was measured with a 4 Fr straight catheter. The PG after endovascular therapy was 6 mm Hg between lesions Ⅰ and Ⅱ.

Outcome and follow-up

The procedure resolved the patient’s symptoms. Moreover, his ABI increased to 1.25 and 1.14 in the right leg and left leg, respectively. Furthermore, we observed an improvement in the serum creatinine level from 2.38 mg/dL to 0.96 mg/dL, 1 month postoperatively.

Discussion

The progression of atherosclerosis after kidney transplantation is not well understood. The patient in this case underwent kidney transplantation 18 years prior to his referral to our hospital. During that period, he was on medication, including prednisolone and cyclosporine (CsA), which are known to contribute to lipid disorders. CsA therapy reportedly reduces LDL receptor activity and increases the serum LDL cholesterol (LDL-C) levels.² The serum LDL-C level of the patient was 151 mg/dL on admission. High LDL-C level is a risk factor for atherosclerosis. However, the benefits of lipid-lowering therapy after kidney transplantation have not yet been explored. Peripheral artery disease guidelines recommend a serum LDL-C level <70 mg/dL or a decrease by >50% if it ranges between 70 mg/dL and 135 mg/dL.⁴ Thus, we prescribed atorvastatin (10 mg/day) based on the aforementioned guidelines. His LDL-C level decreased to 68 mg/dL after 1 month, thus falling below the recommended level.

We conducted a PG study to evaluate the flow response. According to researchers, a measurement of the PG facilitates the treatment of abdominal aortic stenosis.⁵ There is no evidence supporting an appropriate cut-off value of the mean systolic PG for abdominal aortic stenosis treatment. Nonetheless, a mean systolic PG >10 mm Hg was found to justify the use of EVT.⁶ Furthermore, a targeted PG <10 mm Hg is reportedly satisfactory after EVT.⁷

The pretreatment PG at the site of stenosis was 72 mm Hg. Following the stent implantation, it was reduced by 6 mm Hg. The post-treatment IVUS and angiography images revealed signs of approximately 50% stenosis. However, the improvement of the PG helped us avoid a complete stent apposition with an additional post-dilation of the larger balloon.

ASTRAL trial reported that there was no evidence of a worthwhile clinical benefit from EVT in patients with renal artery stenosis. On the other hand, RADAR trial, which was a study comparing best medical therapy (BMT) alone versus BMT plus EVT in patients with renal artery stenosis, showed that there was a tendency of lower rate of clinical events, including cardiac death, stroke, myocardial infarction and hospitalisation for congestive heart failure.^{8 9}

The patient’s atherosclerotic progression increased after kidney transplantation. Despite the contribution of some factors towards this progression, this patient’s case highlights the importance of monitoring atherosclerotic progression after kidney transplantation. In addition to follow-up blood tests, ABI measurement is an effective way to evaluate the calcification of the aorta–iliac artery. Moreover, it could prove beneficial while monitoring patients. Regular CT scans can also facilitate the early detection of atherosclerosis progression after kidney transplantation. Thus, CT should be considered an evaluation tool.¹⁰ In this case, the implementation of EVT for abdominal aortic stenosis improved renal function and reduced claudication, thereby indicating its potential for future studies in similar conditions.

Learning points.

• Following kidney transplantation, patients have an elevated risk of atherosclerotic disease. Those on immunosuppressants have a particularly high risk of developing calcified lesions.

• Endovascular therapy (EVT) is expected to improve renal function after transplantation for renal artery stenosis.

• The usefulness of measuring the pressure gradient during EVT can be attributed to a defined targeted lesion and a decrease in the endothelial dysfunction by limiting the treated area.