Introduction

Colonic Ischemia (CI) after abdominal aortic aneurysm surgery (open or endovascular) is an occasional but at the same time life-threatening complication. The incidence of postoperative CI is around 0,5%-3% [1]. The most ischemic lesions in the colon after aortic reconstructions are located at the sigmoid and rectosigmoid junctions [3]. The open repair of complicated aneurysms exists as one of the main risk factors for postoperative CI [1]. The mortality rate of CI is extraordinary, and it is calculated at>50% [4]. One of the potential solutions to this complication is the Inferior Mesenteric Artery (IMA) reimplantation. However, the option to revascularize the IMA should be directed by specific indications. These indications are included the bilateral internal iliac arteries occlusion and intraoperative CI [2]. Medical literature does not currently contain any randomized control studies that verify the benefit of IMA reimplantation (RIMA) against CI. This case provides a successful example of this procedure.

Case Report

A 62-year-old male patient was admitted to our department for elective restoration of an asymptomatic isolated left common iliac artery aneurysm. His pertinent medical history included arterial hypertension, tobacco abuse, asymptomatic peripheral arterial disease, and a hypoplastic kidney without other evidence of chronic kidney disease. Other comorbidities, such as Chronic Obstructive Pulmonary Disease (COPD) and coronary artery disease, were not revealed. Blood test and arterial blood gas analysis presented no abnormalities (CREA: 0,87 and PO2: 73). Preoperative imaging (computer angiography CTA) indicated an isolated left common iliac artery aneurysm (with a maximum diameter of 4,5cm) (Figure 1) and bilateral internal iliac arteries occlusion. The mesenteric arteries were patent without significant stenosis (Figure 2). Due to the aforementioned factors, an open aortic repair was estimated preferable. In the operation room, an aortobiiliac bypass was constructed using a bifurcated Dacron graft. The left limb of the graft was anastomosed to the external iliac artery in an end-to-end custom. Meanwhile, the right peripheral anastomosis was performed end-to-side to the right common femoral artery, due to unsatisfactory backflow of the external iliac artery. Keeping in mind the preoperative assessment of the IMA, its diameter, backflow and mainly both internal iliac arteries occlusion, reimplantation was considered appropriate to preserve colonic perspiration. The anastomosis was placed end-to-side on the main graft (Figure 3,4). The patient was extubated in the Operating Room (OR) and was transferred to the intensive care unit (ICU) for further monitoring. He remained in the ICU for 72hrs and was subsequently transferred to the Vascular Surgery Department to resume treatment. He was discharged on the seventh postoperative day without complications. Follow-up at 3 months showed no sign of CI, while kidney and respiratory function remained uncompromised.

Figure 1: The aneurysm of the common iliac artery in the CTA.

Figure 2: The inferior mesenteric artery in the CTA.

Figure 3: Intraoperatively, the reimplantation of the IMA.

Figure 4: Intraoperatively, the reimplantation of the IMA.

Discussion

Colonic ischemia is one of the most threatening complications after Abdominal Aortic Aneurysm (AAA) repair, either open or endovascular and in some cases may be mortal. It consists of an urgent medical condition, which is statistically more regular in ruptured and emergency reconstructions compared to elective cases. Furthermore, it is frequently developed after open repair compared to endovascular restoration [1]. Overall, the colon has a well-developed collateral anastomotic network among the celiac axis, the superior mesenteric artery, and the inferior mesenteric artery. These anastomoses can enlarge, be dilated, and form a marginal artery of Drummond, which in turn can provide the entire colonic blood supply. Therefore, even if the atherosclerotic process affects the orifices of one or more of these arteries, most patients remain asymptomatic. However, splenic flexure and sigmoid colon are more susceptible to an ischemic insult when compared to the rest of the colon. Additionally, the marginal artery of Drummond can be absent in about 5% and underdeveloped even in 50% of the population. Consequently, these groups of patients have an increased risk of CI [5].

The typical post-operative signs suggesting CI incorporate bloody diarrhea, abdominal pain, and tenderness over the affected bowel. Unfortunately, these signs and symptoms are often absent or underestimated, and a high index of suspicion should alert the surgeon when the patient is not improved at the expected ratio postoperatively. Elevated lactate levels, high white blood cell count, and increased alkaline phosphatase can be functional along with the clinical signs but are nonspecific. Even though CT is regularly managed as a line first-line imaging modality, early sigmoidoscopy is advocated. Most patients respond to conservative measures, such as intravenous fluids, antibiotics, bowel rest, and avoidance of vasoconstrictive drugs [6]. The appraisal of postoperative CI requires ideally sigmoidoscopy and histologic evaluation of the sigmoid mucosa, because the colonoscopic assessment alone may produce false positive and negative results. Obviously, colonoscopy is indicated for the valuation of mucosal ischemia and gangrene but is not suitable for the diagnosis of transmural ischemia. Although the colonoscopy and the histology evaluation cannot be considered diagnostic for transmural ischemia, both can help identify patients at increased risk [7,8].

Moghadamyeghaneh et al. presented the most noteworthy risk factors for postoperative CI. This study included 3486 patients. Of these patients, 11,6% underwent open reconstruction while 88,4% underwent endovascular repair. In the first group, CI appeared at a frequency of 5,2% and in the second one at a ratio of 1,8%. 77.3% of the patients presented CI on the 4^th postoperative. The statistically significant risk factors for colonic ischemia in open repair were renal failure requiring dialysis, bleeding disorders, diabetes mellitus, ruptured aneurysm, proximal extended aneurysm and aortic aneurysm with a diameter huger than 7cm. RIMA, occluded IMA and ligation of IMA were not statistically significantly associated with postoperative CI. Intraoperative transfusion is an additional risk factor in terms of endovascular repair. That study concludes that AAA operations complicated by postoperative CI are uncommon (incidence rate of 2.2%) but carry associated mortality of 38.7%. Patency of hypogastric arteries, enlarged IMA, congenital absence of the marginal artery of Drummond, or the presence of atherosclerotic disease at the celiac axis or the ostium of the superior mesenteric artery are additional risk factors for CI [1].

RIMA can protect from colonic ischemia after abdominal aortic aneurysm repair, especially in open repair. However, the RIMA should be considered under specific indications. Even though reimplantation is performed at the discretion of the operating surgeon, intraoperative CI, poor back bleeding, enlarged IMA, bilateral internal iliac artery occlusion and/or prior colon surgery are strong indications for such a surgical procedure. [2] In our case, the reason for which the medical team chose the RIMA was the occlusion of both internal iliac arteries. Jayaraj et al. have published clinical research on RIMA. Even though RIMA prevents colonic ischemia, the ten-year survival after such a procedure is severer when intraoperative CI is present. Reimplantation is otherwise associated with excellent long-term patency, minimal risk of CI, and minimal risk of surgical reintervention [2].

Senekowitsch et al. have published their experience on postoperative CI after RIMA during open infrarenal aortic aneurysm repair. RIMA did not diminish the risk of perioperative ischemic colitis (P: 0.203) nor influenced mortality (P:0.102), operation time and blood loss. Therefore, even older patients or those with increased intraoperative blood loss, could benefit from RIMA [3]. Endovascular techniques are minimally invasive procedures that are involved in RIMA too. Kostiuk et al have published a case report wherein the chimney technique occurred for endovascular aneurysm repair and reimplantation of IMA at the same time. They concluded that Endovascular Aneurysm Repair (EVAR) with chimney IMA grafting is an important technique for colonic perfusion preservation in selected patients with aneurysms and peripheral artery disease (P.A.D.) [9]. On the other hand, the value of inferior mesenteric artery reimplantation is still debated. Lee et al., in their retrospective study, the increased operative time, the higher rates of graft infection (P=.009) and the risk of ischemic colitis(P=.027) – although not statistically significant– were mentioned as the main disadvantages of the procedure [10].

Conclusion

Colonic ischemia is an intermittent but simultaneously mortal complication after abdominal aortic aneurysm restoration. Notwithstanding the enriched anastomotic system of the colon, complicated aneurysms and further severe co-morbidities are associated with a high prevalence of colonic ischemia. The reimplantation of the inferior mesenteric artery is a potentially significant technique to diminish the frequency of this complication. However, more research data are demanded to demonstrate its efficacy and validate this procedure, as its position is still in question by the scientific literature.

References

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