Treatment of recurrent iliac branch occlusion after endovascular repair of abdominal aortic aneurysm diagnosed by contrast-enhanced ultrasound combined with computed tomography angiography: a case report

Background: Endovascular treatment of abdominal aortic aneurysm (AAA) has been in use for several decades and has become the main treatment for this disease. Iliac branch occlusion (IBO) is a common complication after endovascular treatment. The diagnosis and guidance of contrast-enhanced ultrasound (CEUS) combined with computed tomography angiography (CTA) in the treatment of recurrent IBO after endovascular aneurysm repair (EVAR) are rarely reported. In this case, CEUS gave important hints on the cause of IBO. Case Description: We present a 67-year-old male patient who was diagnosed with AAA in 2020 and underwent endovascular treatment in the same period. There was no family history of AAA. The operation process was successful. The CTA re-examination one month after operation showed that the aneurysm was well isolated without obvious endoleak. However, the patient developed intermittent claudication of both lower limbs after operation, but did not receive relevant diagnosis and treatment. Four months after surgery, the patient's claudication symptoms of the left lower limb were significantly worse than before, and CTA review revealed left IBO. The left ankle brachial index (ABI) was too low to detect the value. A femoral artery thrombectomy was performed and a stent was extended distal to the left iliac stent. The claudication symptoms improved after surgery. Unfortunately, only two months later, the patient developed rest pain in the left lower limb. CTA examination showed that the left iliac branch was occluded again. The problem in the proximal end of the left iliac branch was observed by CEUS before re- operation, which was also confirmed by digital subtraction angiography (DSA) after thrombectomy. The blood flow was significantly improved after the angle of the proximal iliac branch was adjusted by stent placement. The patient did not show claudication symptoms again during follow-up. Through CEUS, we identified the pathogenic causes which could not be reflected in CTA and formulated the correct treatment plan. Conclusions: The risk factors of IBO after EVAR are mostly hidden in the process of the initial operation. CEUS can provide more information about postoperative hemodynamics than CTA. The role of CEUS in postoperative follow-up of endovascular treatment of AAA needs to be further explored.