Anatomical Description and Clinical Relevance of a Rare Variation in the Mesenteric Arterial Arcade Pattern

Solitary vascular variations of the mesenteric arteries are extremely rare and have been seldom reported in the past. The aim of this study is to emphasize the anatomical and clinical relevance of one such rare variation of inferior mesenteric artery (IMA). The current case anomaly was incidentally observed while guiding the undergraduate medical students in the dissection of the mesenteric region of the abdomen in an Indian cadaver. An Accessory left colic artery was seen to be branching off from the Inferior Mesenteric artery and further dividing into two transverse branches which took part in the formation of arterial arc for the perfusion of the transverse and the descending colon. Awareness of such aberrant branches of Inferior Mesenteric artery helps in optimal selection of the mode of treatment or operative planning. Additionally, this knowledge minimizes possible iatrogenic injuries resulting from surgeries. Moreover, surgical anatomy of anomalous branches of Inferior Mesenteric artery is extremely essential for planning and successfully executing reconstructive procedures using these branches as pedicles for the transposed part of the colon.

Is Inferior Mesenteric Artery Embolization Indicated Prior to Endovascular Repair of Abdominal Aortic Aneurysm?

Type II endoleak is a common condition occurring after endovascular repair of abdominal aortic aneurysms (EVAR), and may result in aneurysm sac growth and/or rupture in a small number of patients. A prophylactic strategy of inferior mesenteric artery (IMA) embolization before EVAR has been advocated, however, the benefits of this strategy are controversial. A clinical vignette allows the authors to summarize the available data about this issue and discuss the possible benefits and risks of prophylactic IMA embolization before EVAR. The authors performed a meta-analysis of available data which showed that the pooled rate of type II endoleak after IMA embolization was 19.9% (95% CI 3.4-34.7%, I2 93%) whereas it was 41.4% (95% CI 30.4-52.3%, I2 76%) in patients without IMA embolization (5 studies including 596 patients: p < .0001, OR 0.369, 95% CI 0.22-0.61, I2 27%). Since treatment for type II endoleaks is needed in less than 20% of cases and this complication can be treated successfully in 60-70% of cases resulting in an aneurysm rupture risk of 0.9%, these data indicate that embolization of patent IMA may be of no benefit in patients undergoing EVAR.

Anterior Resection for Rectal Cancer and Visceral Blood Flow: An Explorative Study

BACKGROUND AND AIMS

Impaired blood perfusion may be implicated in anastomotic leakage after anterior resection for rectal cancer. We investigated whether high ligation of the inferior mesenteric artery or total mesorectal excision compromises visceral blood flow in the colonic limb and the rectal stump, respectively.

MATERIAL AND METHODS

A prospective cohort study was conducted in a university hospital setting. We used Laser Doppler flowmetry to evaluate the impact of level of tie on colonic limb perfusion and the extent of the mesorectal excision on the rectal blood flow. In the rectum, different quadrants were also assessed. The Mann-Whitney U test was used to compare mean blood flow ratios between groups.

RESULTS

Some 23 patients were recruited in a convenience sample during a period in 2012-2013. The mean blood flow ratio was not decreased after high tie compared to low tie surgery (1.71 vs 1.19; p = 0.28). Total mesorectal excision reduced the mean blood flow ratio in the rectum, as compared with partial mesorectal excision (0.76 vs 1.28; p = 0.14). This was especially pronounced in the posterior aspect of the rectum (0.66 vs 1.68; p = 0.02).

CONCLUSION

High tie ligation did not seem to decrease colonic limb perfusion, while total mesorectal excision may decrease rectal blood flow. The posterior quadrant of the rectum might be particularly vulnerable to the dissection involved in total mesorectal excision.

A mixed-type intermesenteric trunk as a major contributor to the ascending, transverse, and descending colons: a case report

PURPOSE

We present a case in which a mixed-type intermesenteric trunk was the major arterial supply for the ascending, transverse, and descending colons.

METHODS

We dissected a cadaver of a man aged 74 years that was used for a routine abdominal dissection course of 2nd year medical students.

RESULTS

We observed that a mixed-type intermesenteric trunk supplied the majority of the colon, originating from the inferior mesenteric artery. The vessel was non-tortuous and had a counter clockwise course. It gave branches that supply the marginal artery at the splenic and hepatic flexures and at the transverse colon and finally it anastomosed with the ileocolic artery at the ileocecal junction. Through the intermesenteric trunk, the inferior mesenteric artery supplied the descending, transverse, and ascending colons with contributions from the sigmoidal and ileocolic arteries.

CONCLUSIONS

The intermesenteric trunk is an important central connection between the superior and inferior mesenteric arteries. It probably is an embryologic remnant that constituted a longitudinal anastomosis between both mesenteric arteries.

High Ligation of Inferior Mesenteric Artery in Left Colonic and Rectal Cancers: Lymph Node Yield and Survival Benefit

During surgery for colorectal cancer, the inferior mesenteric artery (IMA) may be ligated either directly at the origin of the IMA from the aorta (high ligation) or at a point just below the origin of the left colic artery (low ligation). Sixty patients of left colonic and rectal cancer undergoing elective curative surgery in 2007 and 2008 were selected for this observational study. The resected lymph nodes were grouped into three levels: along the bowel wall (D1), along IMA below left colic (D2), and along the IMA and its root (D3). Statistical analysis was performed with SPSS version 20.0. D2 level was involved pathologically in 20 (33.3 %) and D3 in six out of 44 (13.6 %) patients. The median nodal yield with high and low ligation were 33 and 25, respectively (p = 0.048). Median overall survival for high ligation was 62 months versus 42 months for low ligation (p = 0.190). High ligation of the IMA for rectal and left colonic cancers can improve lymph node yield, thus facilitating accurate tumor staging and thus better disease prognostication, but the survival benefit is not significant.

Idiopathic inferior mesenteric arteriovenous fistula: a rare cause of pulsatile abdominal mass

Inferior mesenteric arteriovenous fistula (AVF) is an extremely rare vascular abnormality which may be idiopathic or secondary to previous trauma or surgery, and it may result in portal hypertension or ischemic colitis if left untreated. Imaging can help accurately diagnose visceral AVFs and create a vascular map to display the feeding artery and draining vein before the surgery; however, multidetector computed tomography (MDCT) angiography of inferior mesenteric AVF is not well documented in the literature. In this article, the authors report a case of inferior mesenteric AVF in a 48-year-old woman evaluated for left-sided abdominal pain and diagnosed preoperatively by MDCT angiography. Surgical excision of the AVF was successfully performed, and the postoperative course was uneventful.

Inferior mesenteric arteriovenous fistula: Case report and world-literature review

Arteriovenous fistulas between the inferior mesenteric artery and vein are rare, with only 26 primary and secondary cases described in the literature. Secondary fistulas occur following operations of the left hemicolon and manifest as abdominal pain, abdominal mass, gastrointestinal bleeding, colonic ischemia and portal hypertension. Symptom intensities are flow-dependent, and can range from minimal symptoms to severe heart failure due to left to right shunt. Diagnosis is usually established by radiological or intraoperative examination. Treatment options include embolization and/or surgical resection. Therapeutic decisions should be adapted to the unique characteristics of the fistula on an individual basis. A new case of a primary arteriovenous fistula is described and discussed along with a complete review of the literature. The patient in this report presented with signs and symptoms of colonic ischemia without portal hypertension. The optimal treatment for this patient required a combination of embolization and surgical operation. The characteristics of these rare inferior mesenteric arteriovenous fistulas are examined and some considerations concerning diagnostic and therapeutic strategies that should be followed are presented.

Transanal natural orifice transluminal endoscopic surgery total mesorectal excision in animal models: endoscopic inferior mesenteric artery dissection made easier by a retroperitoneal approach

Purpose

We report the performance of natural orifice transluminal endoscopic surgery (NOTES) low anterior resection in animals using transanal total mesorectal excision (TME) with laparoscopic assistance and endoscopic inferior mesenteric artery (IMA) dissection.

Methods

Four pigs weighing 45 kg each, and one dog weighing 25 kg, underwent surgery via a transanal approach. The rectum was occluded transanally using a purse-string suture, approximately 3-4 cm from the anal verge. The rectal mucosa was incised circumferentially just distal to the purse-string. A SILS or GelPOINT port was inserted transanally. Transanal TME was assisted by laparoscopy and proceeded up to the peritoneal reflection. More proximal dissection, including IMA dissection, was performed along the retroperitoneal avascular plane by endoscopy alone and facilitated by CO₂ insufflation. The IMA was clipped and divided endoscopically. The mobilized rectosigmoid were exteriorized transanally and transected. A colorectal anastomosis was performed using a circular stapler with a single stapling technique.

Results

Endoscopic dissection of the IMA was successful in all five animals. The mean operation time was 125 minutes (range, 90-170 minutes). There were no intraoperative complications or hemodynamic instability. The mean length of the resected specimen was 14.4 cm (range, 12-16 cm).

Conclusion

A NOTES retroperitoneal approach to the IMA with CO₂ insufflation and intact peritoneal covering overcame the difficulties of retraction and exposure of endoscopic dissection in animals.

Inferior Mesenteric Artery Stenting as a Novel Treatment for Chronic Mesenteric Ischemia in Patients with an Occluded Superior Mesenteric Artery and Celiac Trunk

INTRODUCTION

Chronic mesenteric ischemia (CMI) is a challenging problem, with revascularization the mainstay of treatment. Management of CMI is especially challenging in the patient with superior mesenteric artery (SMA) and celiac artery (CA) occlusions.

REPORT

We report a case series of four patients with chronic mesenteric ischemia who were not candidates for CA or SMA revascularization who were successfully treated with inferior mesenteric artery (IMA) angioplasty and stent placement to improve collateral circulation and palliate symptoms.

DISCUSSION

To our knowledge, this is the largest case series to date reporting the use of an IMA stent to improve collateral circulation in patients with CMI.

Are there any surgical and radiological correlations to the level of ligation of the inferior mesenteric artery after sigmoidectomy for cancer?

INTRODUCTION

The Société Française de Chirurgie Digestive and the American Society of Colon and Rectal Surgeons recommend a ligation at the origin of the primary feeding vessel for sigmoid cancer to ensure optimal lymphadenectomy. We evaluated the correlation between the level of ligation defined by the surgeon and the real level of ligation visualized on postoperative CT scan.

PATIENTS AND METHODS

From December 2004 to August 2010, in a series of 146 patients undergoing colectomy for sigmoid cancer, 51 (19 women) CT measurements (visualization of the left colonic artery (LCA), length of the arterial stump) were performed by a radiologist blinded to operative data.

RESULTS

This series comprised 63% of men with a mean age of 69 years. A correlation was demonstrated between the level of ligation assessed by the surgeon and the real level of ligation demonstrated on postoperative CT scan in 41% of cases. No risk factors for absence of correlation were identified (laparoscopy, gender, BMI, emergency, and ASA score). In the "no correlation" group, the site of ligation was overestimated in 70% of cases. No significant difference was observed between the "correlation" and "no correlation" groups for lymphadenectomy (21.6 and 18 lymph nodes, p=0.5593) or 5-year overall survival (71.4 and 93.1 months, p=0.57).

CONCLUSION

In conclusion, the surgical and radiological correlations are low as the intraoperative estimation of the level of IMA ligation was correlated with CT findings in less than 50% of cases. No risk factors for non-correlation were identified, and there was no impact on lymphadenectomy. Overestimation of the level of ligation was the most frequent situation but did not appear to have any impact on tumor staging or on patient management in this group of patients.

Report of a case of ischemic colitis with bilaterally patent internal iliac arteries after endovascular abdominal aneurysm repair

During endovascular aneurysm repair (EVAR), interruption of the internal iliac arteries (IIAs) or the inferior mesenteric artery by stents or embolization is thought to cause colon ischemia. To minimize this risk, attempts have been made to preserve the IIAs using iliac branch devices or IIA revascularization. Here we present our experience of colon ischemia after EVAR in a patient with bilaterally patent IIAs without evidence of embolism. A 70-year-old man had abdominal pain and a ruptured abdominal aortic aneurysm was found. We performed EVAR with custom-made tube grafts preserving the bilateral IIAs. On postoperative day 2, the patient complained of abdominal pain, a sigmoidoscopy was performed revealing colon ischemia. On laparotomy, transmural infarction of the sigmoid colon was found and resected. Because IIA preservation cannot guarantee protection against colon ischemia, surgeons should maintain a high level of suspicion and use surveillance liberally after EVAR for early diagnosis of colon ischemia, even if both IIAs are preserved.

Percutaneous panvascular intervention in an unusual case of extensive atherosclerotic disease

It is common to see patients with atherosclerotic coronary disease and peripheral arterial disease in routine clinical practice. One needs to have a comprehensive and integrated multi-speciality approach and panvascular revascularization in such patients. We report a 54-year-old diabetic hypertensive male with extensive atherosclerotic coronary and peripheral arterial disease, who presented with congestive heart failure, claudication of both lower limbs and mesenteric ischemia. He underwent successful percutaneous panvascular revascularization of coronary, renal, mesenteric, aorto-iliac and superficial femoral arteries. Long-term patency of all the stents was also documented.

Preoperative assessment of vascular anatomy of inferior mesenteric artery by volume-rendered 3D-CT for laparoscopic lymph node dissection with left colic artery preservation in lower sigmoid and rectal cancer

AIM: To determine the distance between the branching point of the left colic artery (LCA) and the inferior mesenteric artery (IMA) by computed tomography (CT) scanning, for preoperative evaluation before laparoscopic colorectal operation.

METHODS: From February 2004 to May 2005, 100 patients (63 men, 37 women) underwent angiography performed with a 16-scanner multi-detector row CT unit (Toshiba, Aquilion 16). All images were analyzed on a workstation (AZE Ltd, Virtual Place Advance 300). The distance from the root of the IMA to the bifurcation of the LCA was measured by curved multi-planar reconstruction on a workstation.

RESULTS: The IMA could be visualized in all the cases, but the LCA was missing in two patients. The mean distance from the root of the IMA to the root of the LCA was 42.0 mm (range, 23.2-75.0 mm). There were no differences in gender, arterial branching types, body weight, height, and body mass index.

CONCLUSION: Volume-rendered 3D-CT is helpful to assess the vascular branching anatomy for laparoscopic surgery.