Endovascular Repair of a Post-Renal Transplant Internal Iliac Artery Pseudoaneurysm

Introduction

Anastomotic site pseudoaneurysm of the iliac artery is an uncommon vascular complication of renal transplantation.^1-3 Its etiology includes vessel wall injury, infections, faulty suture techniques, and chronic graft rejection.^3,4 The clinical manifestations are secondary to allograft dysfunction, local mechanical compression, pseudoaneurysm rupture, and exsanguination. Those with large sized pseudoaneurysm requires surgical or endovascular interventions. We hereby present a case of large internal iliac artery pseudoaneurysm with common iliac vein compression, which was successfully treated by endovascular stenting.

Case Report

A 63-year-old male of end-stage renal disease underwent successful live unrelated renal allograft transplantation. The donor kidney was anastomosed to the right internal iliac artery (IIA). After a month of surgery, he presented with insidious onset pain and swelling in the right iliac fossa, along with pitting pedal edema of the right lower limb (Figure 1A). His serum creatinine and eGFR were 1.3 mg/dl and 58 ml/min/1.73 m2, respectively. Doppler examination showed a 32 x 40 mm pulsatile swelling posterior to the transplanted renal artery (TxRA), which was compressing the right common iliac vein (CIV). A computed tomography (CT) angiography revealed a large pseudoaneurysm measuring 43 X 41 X 42 mm, with a wide neck arising from the right IIA at the anastomotic site (Figure 1B). A contrast angiogram confirmed a large leaking pseudoaneurysm with a wide neck, arising from the junction of right IIA to the TxRA (Figure 1C and D). The venogram confirmed 95% narrowing of right CIV (Figure 1E). He was considered for the endovascular repair of the pseudoaneurysm. Two overlapping 6 X 22 and 6 X 28 mm balloon-expandable stent-grafts (BeGraft stent, Bentley InnoMed GmbH, Germany) were deployed from IIA to TxRA. The stented segment was post-dilated with an 8 X 40 mm peripheral balloon (Cooks Medical, Bloomington, Indiana, US). There was a good flow across TxRA with no endoleak (Figure 2A). He was discharged on dual anti-platelet (aspirin and clopidogrel) and immunosuppressive therapy. The right lower limb swelling persisted even after 2-months of follow-up. The repeat venogram showed persisted 95% stenosis of the right CIV (Figure 2B). It was successfully stented with a 28 x 80 mm self-expanding stent (Sinus-XL stent, Optimed, Ettlingen, Germany) (Figure 2C and D). The right lower limb swelling gradually improved in the next 1 week (Figure 2E). He remained asymptomatic during 16 months of clinical follow up. His serum creatinine and eGFR normalize to 0.8 mg/dl and 95 ml/min/1.73 m2, respectively after a month of IIA intervention. A repeat CT angiography showed patent stents of both TxRA and right CIV at 6 months of follow-up (Figure 2F).

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Figure 1.

Right lower limb swelling due to compression of the right common iliac vein (CIV) by pseudoaneurysm (A). A volume-rendered 3D Computed tomography (CT) angiogram showed a large pseudoaneurysm arising from the anastomotic site of the right internal iliac artery (IIA)- transplanted renal artery (TxRA) (B). A selective catheter angiogram showed the active leaking site of the pseudoaneurysm (C and D, white arrow). A venogram confirmed 95% stenosis of CIV (E) due to external compression by the pseudoaneurysm.

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Figure 2.

The IIA pseudoaneurysm was excluded by the stent-grafts (A). A venogram after 2 months of stent-graft intervention showed persisted right CIV stenosis (B). Normal flow across the CIV was achieved following stent implantation (C). Fluoroscopy revealed CIV and transplanted renal artery stents in-situ (D). The right lower limb swelling subsided following CIV intervention (E). A repeat CT at 6 months of follow-up showed patent stents of TxRA and CIV (F).

Discussion

Vascular complications following renal transplantation are common, ranging from 1.3 to 9% in various series.^1,2,5 It includes renal artery and vein thrombosis, renal artery stenosis, pseudoaneurysm and iliac artery dissection.^1,2 Pseudoaneurysm is one of the rare complications found in less than 1% of cases.^1,2,4 Its etiologies include iatrogenic vessel wall injury, defective suture/vascular reconstruction techniques, infections and chronic rejection.^1,3,6 Pseudoaneurysms related to defective suturing occur at the anastomotic site, while mycotic aneurysms secondary to infection can be at multiple sites across the vascular reconstruction. ⁴ There was no symptoms or signs of infection/inflammation in the index case, which rules out an infected mycotic aneurysm. The pseudoaneurysm was possibly because of defective suturing at the anastomotic site. The small, asymptomatic pseudoaneurysms are usually detected during ultrasound surveillance, while the larger one become symptomatic and present as a pulsatile mass associated with local pain, tenderness, allograft dysfunction, ipsilateral lower limb swelling, exsanguination and rupture.^1-3 The indications for intervention includes presence of symptoms, allograft dysfunction, size greater than 2.5 cm, rapid increase in size, and or impending rupture.^3,6 The index case required intervention because of the large size, associated allograft dysfunction and mechanical compression of CIV. The open surgical repair of such a large pseudoaneurysm requires vascular reconstruction, which has the risk of renal ischemia, loss of the graft and significant morbidity of repeat surgery.^3,6 Endovascular stent-graft is a less invasive, alternative treatment for such a large internal iliac pseudoaneurysm. It helps to preserve allograft kidney along with improvement in function. ⁷ Other endovascular treatment such as coil embolization or thrombin/glue injection can be effective for smaller pseudoaneurysm, but not effective in wide-necked large pseudoaneurysm as in the index case. ⁴

Endovascular stenting has become a standard therapeutic intervention for iliofemoral venous obstruction. ⁸ A meta-analysis demonstrated its safety and efficacy in the majority of venous obstructions related to acute thrombotic, non-thrombotic and chronic post-thrombotic etiologies. ⁹ Following the exclusion of IIA pseudoaneurysm in the index case, we expected the regression of pseudoaneurysm sac and improvement in the external compression of the right CIV. However, there was persistent venous obstruction even after 2 months of pseudoaneurysm treatment, henceforth, additional endovascular stenting of CIV was performed. Efficacy of endovascular stenting for CIV extra-luminal compression is well described in the literature.^9,10

In conclusion, we hereby report a rare case of large IIA pseudoaneurysm in a post-renal transplant patient, who had successful endovascular stenting of pseudoaneurysm and externally compressed CIV. He had favorable clinical outcomes at 16 months of follow-up.