Colonic hypoperfusion following ligation of the inferior mesenteric artery in rectosigmoid colon cancer patients

Abstract

Purpose: Colon perfusion status is one of the most important factors for the determination of postoperative anastomotic complications. Colonic hypoperfusion can be induced by inferior mesenteric artery (IMA) ligation in some patients. This study aimed to evaluate atherosclerotic risk assessment and vascular parameters of CT angiography as predictors of colonic hypoperfusion.

Methods: This prospective study was conducted at a tertiary referral hospital and included 46 rectosigmoid colon cancer patients undergoing laparoscopic anterior resection between August 2013 to July 2014. Atherosclerotic risk scores were assessed using the Framingham cardiovascular risk score system. The IMA length, branching pattern, atherosclerotic calcification, and intermesenteric artery and mesenteric vascular diameters were evaluated using CT angiography. Mesenteric marginal artery pressures were measured before and after IMA clamping. The mean arterial pressure (MAP) index was calculated by dividing the mesenteric marginal MAP into the systemic MAP to determine the mesenteric hypoperfusion status after IMA clamping. A critically low MAP index was defined as <0.4.

Results: Critically low MAP index (<0.4) was observed in 6 cases (13.0%) after IMA clamping. Atherosclerotic calcification of the IMA and superior mesenteric artery occurred in 11 (23.9%) and 5 patients (10.9%), respectively. Low MAP index was associated with high atherosclerotic risk score and short IMA length, rather than atherosclerotic calcification and other vascular parameters of the major mesenteric arteries. Multivariate analysis indicated that high atherosclerotic risk and short IMA length were independent predictors of critically low MAP index.

Conclusion: Atherosclerotic risk assessment and IMA length were useful predictors of the mesenteric hypoperfusion status following IMA ligation during laparoscopic rectosigmoid colon surgery.

Keywords: Arterial pressure; Atherosclerosis; Computed tomography angiography; Hypoperfusion; Inferior mesenteric artery.

Fig. 1. CT angiography evaluation of mesenteric vascular properties. Inferior mesenteric artery (IMA) branching types; left colic artery (LCA) first (A), superior rectal artery (SRA) first (B), LCA, SRA, and sigmoidal artery branching simultaneously (C). (D) Internal diameter of IMA. (E) Intermesenteric artery. (F) Atherosclerotic calcification of IMA orifice.

Fig. 2. (A) Lymph node dissection was continued along the inferior mesenteric artery (IMA) to first bifurcation point and the branches of the IMA were identified. The superior rectal artery (SRA) and sigmoid artery were ligated while preserving the left colic artery. (B) After the transection of proximal colon, the remaining colonic mesentery was divided to leave a marginal artery and a 24-gauge intravascular catheter was cannulated to measure mesenteric arterial blood pressure.

Fig. 3. Hemodynamic changes in the marginal artery according to inferior mesenteric artery (IMA) clamping. (A) The mean arterial pressure (MAP) alterations of the marginal artery before and after IMA clamping. (B) MAP index changes after IMA clamping. (C) Critically low MAP index after clamping (<0.4). (D) Histogram of MAP index after clamping.

Fig. 4. Curve estimation regression graphs for critical hemodynamic alteration and predictive factors. (A) MAP index after clamping is significantly associated with the atherosclerotic risk score and (B) inferior mesenteric artery (IMA) length.