From the Research
If the inferior mesenteric artery is inadvertently ligated, the sigmoid colon's blood supply is maintained through collateral circulation, primarily via the marginal artery of Drummond and the arc of Riolan. These collateral pathways connect the superior mesenteric artery (SMA) to the distal branches of the IMA, ensuring continued perfusion to the sigmoid colon. The marginal artery of Drummond runs along the mesenteric border of the colon, creating anastomoses between the SMA and IMA systems. The arc of Riolan (meandering mesenteric artery) provides a more direct connection between the middle colic artery (from the SMA) and the left colic artery (from the IMA) 1. Key points to consider include:
- The adequacy of this collateral circulation varies between individuals, and some patients may still develop ischemia of the sigmoid colon following IMA ligation, particularly if they have poor collateral development or if multiple vascular territories are compromised simultaneously.
- Patients with pre-existing vascular disease often have better-developed collateral circulation and may tolerate acute IMA ligation better than those with previously normal vasculature 2.
- The development of these collateral pathways is influenced by factors such as chronic vascular insufficiency, including atherosclerosis, which can lead to the formation of anastomoses between different vascular territories 3, 4, 5. In clinical practice, it is essential to consider the individual patient's vascular anatomy and the potential risks of ischemia when ligating the inferior mesenteric artery, and to take steps to minimize these risks, such as maintaining adequate blood pressure and ensuring sufficient collateral circulation 1.