To describe a novel endovascular technique in the management of a complex arteriovenous fistula between a large internal iliac artery aneurysm and the adjacent iliac vein in a 76-year old patient with previous aortobifemoral bypass graft with an occluded proximal common iliac artery.
Due to the high risk of open surgery in this case, endovascular treatment with simultaneous venous and arterial access was performed, with implantation of 2 stent grafts in the iliac vein to cover the fistulous communication and embolisation of the native external iliac artery (inflow).
The endovascular technique described enables thrombosis of the large internal iliac aneurysm and treatment of the arteriovenous fistula without exposing the patient to the high morbidity and mortality associated with open surgery.
Rupture or fistulisation of an iliac artery aneurysm into the adjacent vein is rare . The signs and symptoms occur as a result of venous hypertension and patients can present with a distinct triad of findings described by McAuley et al.: rapid onset high output cardiac failure, pulsatile pelvic mass accompanied by a thrill and bruit, and unilateral lower extremity oedema or venous engorgement . Few case reports describe the endovascular management of internal iliac artery aneurysm with fistulous communication to adjacent iliac vein . However, there are no reports of endovascular management of such a fistula in a patient with previous aortobifemoral bypass graft with an occluded proximal common iliac artery.
A 76-year old male patient presented with increasing exertional dyspnoea and a recent history of left lower limb pain and swelling with confirmed deep vein thrombosis on Doppler ultrasound which was treated with oral anticoagulation. His past medical history included recent stroke and ischaemic heart disease with previous myocardial infarction and coronary artery bypass grafting. He also had an aortobifemoral bypass graft performed 20 years prior to this presentation. CT pulmonary angiogram showed no evidence of pulmonary embolism but there were moderate bilateral pleural effusions and interstitial changes suggestive of cardiac failure. An arterial phase contrast-enhanced abdominal CT showed a patent aortobifemoral bypass graft with a large aneurysm involving the left internal iliac artery measuring 9.5 cm in maximum axial dimension, which was compressing the ipsilateral common and external iliac vein ( Fig. 1 A ). There was dense enhancement of the vein and inferior vena cava, equivalent and simultaneous to that of the iliac artery, consistent with an arterio-venous communication. The aneurysm was filling retrogradely from the native left external iliac artery ( Fig. 1 B). 3D coronal and sagittal reconstructions showed a fistulous communication between the internal iliac artery aneurysm and the adjacent common and external iliac vein with early enhancement of the vein. Subsequent catheter angiography was performed to further assess the aneurysm and the arteriovenous fistula. It demonstrated that the inflow to the aneurysm was backfilling through the native left external iliac artery ( Fig. 2 A ) and also showed the fistulous communication with the left common iliac vein causing contrast opacification of the iliac vein and inferior vena cava ( Fig. 2 B).
The findings were discussed at the vascular multidisciplinary meeting. In view of the patient’s comorbidity and the presence of a hostile abdomen because of previous aortobifemoral graft bypass surgery, the decision was made to perform endovascular repair in order to avoid the significant risks associated with open surgery. Endovascular repair of iliac artery aneurysms has been shown to have significantly lower complication rates than surgery .
The procedure was performed by two consultant interventional radiologists experienced in the endovascular treatment of iliac artery aneurysms. The venous system was accessed via right jugular vein puncture and insertion of a 12-French sheath (Cordis Endovascular, Division of Johnson & Johnson, Miami, FL). Retrograde arterial access was also attained with ultrasound-guided puncture of the native left common femoral artery and insertion of 6F sheath. A 14 mm × 12 cm Fluency (Bard Peripheral Vascular, Tempe, Arizona, USA) self-expanding Nitinol stent graft was placed in the iliac vein across the fistula from the common to the external iliac vein. The stent was dilated with balloon post deployment. However the fistula remained patent likely due to the high arterial flow. The fistulous communication was accessed with a catheter and 12 and 10 mm 0.035 inch Nester embolisation coils (Cook Medical, Bloomington, IN, USA) were placed in the outflow tract of the left internal iliac vein. The stent graft was further buttressed with a 16 mm × 6 cm Wallstent (Boston Scientific, Natick, MA, USA) and again dilated with balloon post deployment to force opposition to the vessel wall. Subsequently embolisation of the inflow (left external iliac artery) was performed with 8 and 12 mm Amplatzer Vascular Plug II (AGA Medical Corporation, Golden Valley, MN, USA) and Nester embolisation coils.
A good angiographic result was seen ( Fig 3 A and B). Fig. 4 A and Fig. 4 B illustrate the pre- and post-treatment situation. Follow-up ultrasound examination 24 h after the procedure showed thrombosis of the left internal iliac aneurysm with no internal flow. CT scans after 6 and 18 months showed that the aneurysm remained thrombosed and had decreased in size to 8.5 and 7.3 cm respectively (initial size 9.5 cm) with no arterial phase enhancement of the iliac vein ( Fig. 5 ).