Endovascular therapy for aneurysmal dilatation and arteriovenous fistula of the superior mesenteric artery

Discussion

Superior mesenteric arteriovenous fistula (SMAVF) is a rare condition in clinical practice, and its clinical symptoms are often atypical. Patients with SMAVF may present with abdominal pain and diarrhea, which can be attributed to intestinal ischemia resulting from high-flow shunts.

¹SMAVF is characterized by an anomalous communication between the SMA and the SMV. This condition can be either congenital or acquired, with bowel surgery and abdominal trauma being the most common causes of acquired SMAVF. ¹ Iatrogenic SMAVF typically arises from mass ligation during intestinal resection or from ligation of the mesentery without precise localization of the bleeding point. ² In this case, the patient had no history of abdominal trauma, pancreatitis, or gastrointestinal infection and no obvious scars were observed on the patient’s abdomen during the physical examination. It was determined that the patient’s SMAVF was likely congenital. Treatment options for SMAVF include surgical and endovascular interventions, with the latter being preferred in most cases due to its association with reduced morbidity, lower costs, and the ability to repeat the intervention if necessary; case reports indicate that endovascular interventions may involve coil embolization and stent placement.^3,4 SMAA are rare, accounting for 6% to 15% of all visceral aneurysms (VAAs). ⁵ While infection is believed to be the most common cause of SMAA, current evidence suggests that degenerative conditions, connective tissue diseases, and inflammatory disorders (such as pancreatitis, vasculitis, spontaneous dissection, fibromuscular dysplasia, and polyarteritis nodosa) are potential causes. ⁶ According to the Society for Vascular Surgery VAA guidelines, all SMAA and pseudoaneurysms should be repaired regardless of their size. ⁷ Recent trends have shifted toward endovascular repair using covered stents and transcatheter embolization. ⁸ Evidence for endovascular VAA repair indicates success rates ranging from 93.3% to 98.3%, with major and minor complication rates ranging from 1.8% to 3.6% and 8.9% to 10.5%, respectively. Procedure-related complications may include hematoma, vascular dissection, splenic infarction, intestinal ischemia, aneurysm reperfusion, and stent thrombosis.^8,9

In this case, endovascular therapy provided a viable alternative to open resection for a patient with a large aneurysm and arteriovenous fistula of the superior mesenteric artery. By utilizing covered stents and coil embolization, the abnormal vessel communication was addressed, and the aneurysm was effectively managed. This case highlights the importance of considering individual patient factors and tailoring the treatment approach accordingly to achieve optimal outcomes in complex vascular conditions. Further follow-up and monitoring will be necessary to evaluate the long-term efficacy and durability of the endovascular treatment.