## 2 Anatomy and Pathophysiology  
The splanchnic vascularization is provided by the following:  
* Celiac Trunk (CT): The first branch of the abdominal aorta and distributes blood to the upper abdominal organs, dividing into three branches: the left gastric artery supplies the proximal part of the stomach's lesser curve and the distal part of the esophagus, the splenic artery supplies the proximal and middle parts of the stomach's greater curve, stomach fundus, pancreas, and spleen, and the common hepatic artery supplies the liver, stomach pylorus, gallbladder, proximal part of the duodenum, pancreatic head, and distal parts of the stomach's curves. * Superior Mesenteric Artery (SMA): Arises from the abdominal aorta and supplies the midgut. It provides blood to the distal portion of the duodenum, jejunum, ileum, cecum, ascending colon, and the proximal two-thirds of the transverse colon. * Inferior Mesenteric Artery (IMA): Arises from the abdominal aorta and supplies the hindgut. It vascularizes the distal one-third of the transverse colon, descending colon, sigmoid colon, and the upper part of the rectum. * Hypogastric Arteries (HAs): Also known as the internal iliac arteries, provide blood to the pelvic organs, glutel region, and perineum, supplying the bladder, the reproductive organs, the rectum, and the medial compartment of the thigh. All these arteries are interconnected through anastomotic arches:
* The arch of Buhler: Results from the anastomosis between the superior (CT) and inferior (SMA) pancreaticoduodenal arteries. * The marginal arch of [PERSON]: Runs along the mesenteric insertion of the transverse and left colon and is composed of the middle colic artery (SMA) and the left colic artery (IMA). * The arch of [PERSON]: A collateral circle connecting the left colic artery (IMA) and the ascending branch of middle or right colic artery (SMA). In the general population, there is great anatomical variability, and these anastomocircles may not be fully developed. Approximately, in 5% of cases some of these anastomoses may be lacking, leading to a higher risk of CI [4]. This collateral arterial network performs a crucial compensatory role when one or two visceral vessels are occluded or significantly stenotic, helping to maintain visceral perfusion and prevent gastrointestinal ischemia. The presence of multiple arterial collateral circulations often limits the extension and severity of ischemic clinical manifestations. Conversely, the interruption of the IMA is generally well tolerated in both open and endovascular repair due to the extensive collateral network between the SMA and hypogastric arteries, provided these vessels are patent and free of significant disease. Blood circulation in intermesenteric circulation can be bidirectional. In cases of otstial occlusion of the SMA, the arches of Drummond and Riolan are perfused in a caudocranial direction. Otherwise, in cases of infrarenal aorto-iliac occlusion, the blood flow goes in a cranio-caudal direction through the IMA, moving retrogradely through the colic arches (Drummond and Riolan) to revascularize the SMA via the middle colic artery. In some cases of aorto-iliac occlusion, mesenteric circulation contributes to the perfusion of the lower limbs through collateral vessels between the SMA, the IMA, and, through hemorrhoidal circulation, the hypogastric arteries, ultimately reconstituting collateral circulation at the femoral level. However, there are some vulnerable points in this network particularly prone to the development of CI: [PERSON]'s point, located at the left colic flexure between the ascending left colic artery and the marginal artery of Drummond; [PERSON]'s point, located at the origin of the last sigmoid artery in the region of the sigmoid colon [5]; and Reiner's critical segment, a segment of the SMA between the region above the origin of the second intestinal artery and the middle colic artery and the region below the origin of the ileocolic artery (Figure 1).