A case of arteriovenous malformation in the inferior mesenteric artery region resected surgically under intraoperative indocyanine green fluorescence imaging

Abstract

Introduction and importance: An arteriovenous malformation (AVM) is defined as a vascular malformation with a short, non-capillary communication between the arteries and veins. Most gastrointestinal AVMs are solitary, occurring predominantly in the stomach, small intestine and right colon, and rarely in the inferior mesenteric artery (IMA) region.

Case presentation: A 70-year-old man was first diagnosed with ischemic enteritis two years earlier, and was hospitalized several times with the same diagnosis. He visited our hospital because of left lower abdominal pain and melena. Colonoscopy showed findings suggestive of ischemic enteritis, and contrast-enhanced computed tomography (CT) and IMA angiography showed hyperplasia and dilation of blood vessels from the sigmoid-descending colon junction to the upper rectum. We performed conventional laparoscopic low anterior resection using intraoperative intravenous injection of indocyanine green (ICG). The final diagnosis was arteriovenous malformation in the IMA region. The patient had an uneventful postoperative course and was discharged on the 13th day after the operation.

Clinical discussion: Cases of AVM in the IMA region are relatively rare. This is the first reported case of AVM in the IMA region that was resected under intraoperative ICG fluorescence imaging (FI), which provided useful information on the extent of intestinal resection and mesenteric dissection required, and confirmed the adequacy of intestinal blood flow during and after mesenteric dissection and anastomosis.

Conclusion: It is advisable to use ICG FI intraoperatively during resection of AVMs in the IMA region, as with colorectal cancer surgery.

Keywords: Arteriovenous malformation; Indocyanine green; Inferior mesenteric artery angiography; Laparoscopic surgery.

Fig. 1

Colonoscopy findings. Ischemic enteritis and stenosis were observed from the sigmoid-descending colon junction to the upper rectum.

Fig. 2

Contrast-enhanced computed tomography and inferior mesenteric artery (IMA) angiography findings. a) Extensive intestinal wall thickening, hyperplasia and dilation of blood vessels near the intestinal tract were seen in the IMA region b) The caudal-most part of the nidus was at the level of the peritoneal reflection on the left side of the rectum c) Hyperplasia and dilation of blood vessels from the sigmoid-descending colon junction to the upper rectum were present.

Fig. 3

Operative findings. a) Intestinal wall and mesenteric thickening in the inferior mesenteric artery (IMA) region b) Indocyanine green (ICG) fluorescence imaging (FI) showed diminished fluorescence of the intestinal wall and mesenteric thickening, along with enhanced fluorescence in the surrounding area of hyperplasia. c) We confirmed the adequacy of intestinal and mesenteric blood flow by ICG FI after mesenteric dissection d) We confirmed the adequacy of blood flow at the anastomotic site by ICG FI.

Fig. 4

Macroscopic evaluation of the excised specimen. The intestinal tract was edematous, thickened and narrowed, and the mesentery was swollen and stiff.

Fig. 5

Histopathological evaluation of the excised specimen. a, b) Immunostaining (Hematoxylin-Eosin): Many large and small blood vessels grew in a nodular manner, along with dilatation of the blood vessels and irregularly distributed blood clots. c, d) Immunostaining (Elastica van Gieson): The blood vessels were variously thickened, thinned, and lacked elastic fibers in the blood vessel wall, and, for many of the vessels, it was unclear whether they were arteries or veins.