Ischemic disorders of the intestines

Colon ischemia: A comprehensive review

The clinical and endoscopic features of colon ischemia (CI) are non-specific. CI is correctly identified at the time of presentation in only 9% of patients is. The true incidence is likely underestimated because many mild cases resolve spontaneously without medical treatment. Furthermore, since most cases of CI are transient, and no specific cause is detected they are often considered to be "idiopathic". In the setting of severe CI correct diagnosis and prompt recognition and therapy as well as identification of underlying causes are crucial for a favourable outcome. Although less severe, mild cases may present with similar symptoms, the prognosis and management are completely different and managed conservatively rather than with surgery. Unfortunately, data from most studies and current guidelines do not provide recommendations on the long-term management of CI or about the need for endoscopic follow-up to detect the development chronic, recurrent and/or ischemic colonic strictures. In this review, we focus on the definition of CI, its aetiology, and patterns of presentation. We highlight the pharmacological and/or endoscopic management as determined severity of disease that allow for improved outcomes. Prompt recognition and treatment using a multidisciplinary approach are essential for successful management of severe CI because mortality rates are significantly higher when the diagnosis is delayed.

The importance of the Moskowitz artery as a lesser-known collateral pathway in the medial laparoscopic approach to splenic flexure mobilisation and its evaluation with preoperative computed tomography

INTRODUCTION

The collateral pathways between the superior mesenteric artery (SMA) and inferior mesenteric artery (IMA) play an important role in colonic surgery. The most well-known are the Drummond marginal artery and Riolan's arch. The Moskowitz artery, also known as the meandering mesenteric artery, is a lesser-known collateral pathway and represents another link between SMA and IMA. The Moskowitz artery runs along the colonic mesentery floor and represents the link between the proximal segment of the middle colic artery and the ascending branch of the left colic artery.

AIM

To comprehend the presence and importance of the Moskowitz artery (meandering mesenteric artery) in preoperative patients by using computed tomography (CT) studies.

MATERIAL AND METHODS

We retrospectively reviewed all abdominal CT images performed using intravenous contrast for any reason at the Radiology Department of Yeditepe University Hospital between April 2015 and September 2018. Patients older than 18 years with intravenous contrast (arterial and venous phases with a cross-section thickness of 0.625 mm), who underwent abdominal CT scan, and patients without any abdominal surgery were included in the study. As a result of the screening, 109 CT scans with eligibility criteria were included in this study.

RESULTS

There were 109 cases in this study; 50 (45.9%) of them were male and 59 (54.1%) were female. Moskowitz artery was found in 18 (16.5%) cases; 8 were males and 10 were females. Riolan's arch was present in 30 cases, of whom 15 were male and 15 were female. In our study Moskowitz artery and Riolan's arch were monitored as separate vascular structures, and in all cases with Moskowitz artery, Riolan's arch was also present. There was a statistically significant difference (p < 0.05) between the combined MCA emerging type and the presence of MA, and 12 cases with combined branch and 6 cases with single branch had Moskowitz artery. There was a statistically significant difference (p < 0.05) between LCA types and the presence of MA, and the Moskowitz artery was the most common seen at type 1 LCA.

CONCLUSIONS

Knowledge of the relationship between Riolan's arch and the Moskowitz artery is valuable, and preoperative evaluation of this artery may be beneficial in the presence of Riolan's arch. In addition, preoperative radiological evaluation and its importance are prominent in minimising intraoperative bleeding during splenic flexure mobilisation with a medial laparoscopic approach and reducing the risk of colorectal anastomosis leakage.

Many faces of acute bowel ischemia: overview of radiologic staging

Acute bowel ischemia (ABI) can be life threatening with high mortality rate. In spite of the advances made in diagnosis and treatment of ABI, no significant change has occurred in the mortality over the past decade. ABI is potentially reversible with prompt diagnosis. The radiologist plays a central role in the initial diagnosis and preventing progression to irreversible intestinal ischemic injury or bowel necrosis. The most single imaging findings described in the literature are either non-specific or only present in the late stages of ABI, urging the use of a constellation of features to reach a more confident diagnosis. While ABI has been traditionally categorized based on the etiology with a wide spectrum of imaging findings overlapped with each other, the final decision for patient’s management is usually made on the stage of the ABI with respect to the underlying pathophysiology. In this review, we first discuss the pathologic stages of ischemia and then summarize the various imaging signs and causes of ABI. We also emphasize on the correlation of imaging findings and pathological staging of the disease. Finally, a management approach is proposed using combined clinical and radiological findings to determine whether the patient may benefit from surgery or not.

Incidental Malignant Colonic Polyp Detected in a Resected Ischaemic Large Bowel: A Case Report and Literature Review

Most patients with bowel cancer are symptomatic at the time of the diagnosis. They may present with a change in bowel habit, bleeding per rectum, abdominal pain, anaemia, weight loss or bowel obstruction. Colonic carcinoma can also be diagnosed incidentally during screening programs. Moreover, it may be incidentally detected in CT scans being performed for other indications or encountered during surgery for other causes. Some patients with colonic bowel ischaemia have associated large bowel cancer, where the ischaemic segment is usually proximal to the tumour and not necessarily associated with bowel obstruction. We are presenting a rare case of incidental malignant colonic polyp detected in a resected ischaemic large bowel in an 88-year-old gentleman. This was a very small tumour that was not visible macroscopically or detectable by imaging. Pathological examination of non-tumour colorectal resection specimens, as in this case, should include careful macroscopic examination and sequential block selection along the length of the colon, and where there is diffuse mucosal abnormality, block selection at 100mm interval is also advised. Attention to and block selection from any suspicious-looking area is warranted in all cases of non-tumour colorectal resections if such microscopic-sized malignancies of the type seen in our patient are to be picked up.

Early and Midterm Outcomes of Open and Endovascular Revascularization of Chronic Mesenteric Ischemia

Background

Revascularization strategies for chronic mesenteric ischemia (CMI) include open (OR) and endovascular (ER) modalities. The primary objective of this study was to analyze the safety and effectiveness of OR and ER and the impact of clinical and morphological variables on early and midterm outcomes in a consecutive series of CMI patients in a tertiary referral center.

Patients and methods

From 2004 to 2017, all CMI patients treated with OR and ER were retrospectively identified. Patient records, preoperative imaging, as well as peri- and postoperative outcomes were analyzed. Univariable and multivariable analysis was performed to identify clinical or morphological variables affecting reintervention rates within 2 years.

Results

In total, 63 patients (33% male; mean age 71, range 60–76 years) were treated by ER (41 patients) or OR (22 patients) for CMI. Mean follow-up was 26 (10–71) months. 30-day mortality was 0.0% after ER and 4.5% after OR (p = 0.069); 30-day morbidity was 9.8% vs. 31.8%, respectively (p = 0.030). Length of stay was significantly longer after OR (14 vs. 4 days; p < 0.001). Freedom from reintervention rate after 2 years was 82% after OR and 73% after ER (p = 0.14). Overall survival did not differ after 2 years (OR 85% vs. ER 86%; p = 0.35). Multivariable analysis revealed that smoking was associated with higher risk of reintervention (hazard ratio, HR: 4.14; 95% confidence interval, CI 1.11–15.53; p = 0.03). Additionally, a nonsignificant trend of lower reintervention rates after OR was detected (HR 0.23 95% CI 0.05–1.08; p = 0.06).

Conclusion

Due to a lower invasiveness, despite the higher reintervention rate, an “endovascular first” strategy is justified and recommended.

Doppler ultrasonographic evaluation of celiac and mesenteric arteries in subjects with sickle cell disease

Vasculopathy, as occurring in sickle cell disease (SCD), can affect celiac and mesenteric arteries and result in stenosis, with elevated peak systolic velocity (PSV) on Doppler ultrasonography. In six subjects with confirmed SCD in steady state, routine Doppler ultrasonographic examination discovered features of celiac artery (CA) or superior mesenteric artery (SMA) stenosis with CA PSV >200 cm/s (median = 222.8 cm/s; range = 201.5-427.1 cm/s) and/or SMA PSV >275 cm/s (median 183.2 cm/s; range = 87.8-289.3 cm/s). Among the six subjects, five had elevated soluble P-selectin values (median 72.55 ng/mL), while all six (100%) had elevated cystatin C levels (median 4.15 mg/L). Peripheral oxygen saturation was suboptimal in five subjects. All subjects had low hemoglobin concentration levels (median 8.5 g/dL) while four had elevated white blood cell count. Although vaso-occlusive crises result from microvessel occlusion, these findings at the macrovascular level suggest that SCD patients may also be vulnerable to mesenteric ischemic injury, especially in the setting of anemic heart failure from hemolysis.

Acute mesenteric ischaemia: a pictorial review

Abstract

Acute mesenteric ischaemia (AMI) is an uncommon cause of acute hospital admission with high mortality rates (50–90%) that requires early diagnosis and treatment. With the increase in average life expectancy, AMI represents one of the most threatening abdominal conditions in elderly patients. Untreated, AMI will cause mesenteric infarction, intestinal necrosis, an overwhelming inflammatory response and death. Early intervention can reverse this process leading to a full recovery, but the diagnosis of AMI is difficult. The failure to recognise AMI before intestinal necrosis has developed is responsible for the high mortality of the disease. Unfortunately, common CT findings in bowel ischaemia are not specific. Therefore, it is often a combination of nonspecific clinical, laboratory and radiological findings that helps most in the correct interpretation of CT findings. The purpose of this article is to provide an overview of the anatomy, physiology of mesenteric perfusion and discussions of causes, pathogenesis and CT findings in various types of acute bowel ischaemia. Familiarity with various imaging features of mesenteric injury is essential to make a timely diagnosis that will lead to improved patient outcomes.

Teaching Points

• AMI is a potentially life-threatening disorder whose prognosis depends on early recognition, accurate diagnosis and timely intervention.

• Arterial inflow occlusion due to thrombosis or embolisation is the most common cause of AMI.

• Four aetiological types of AMI have been associated with different characteristics and risk factors (EAMI, TAMI, VAMI and NOMI).

• Physical examination and laboratory findings are not sensitive or specific for diagnosing AMI; therefore, MDCT is still the first-line imaging method in suspected AMI.

• Although a number of scoring systems for prognosis have been proposed, these have not been validated in large-scale studies.

Importance of the Moskowitz artery in the laparoscopic medial approach to splenic flexure mobilization: a cadaveric study

BACKGROUND

The medial approach in laparoscopic splenic flexure mobilization is based on the entrance to the lesser sac just above the ventral edge of the pancreas (VEOP). The artery of Moskowitz runs through the base of the mesocolon, just above the VEOP. The aim of this study was to assess the incidence of the artery of Moskowitz, its route and its distance from the VEOP.

METHODS

We performed a cadaveric study on 27 human cadavers. The vascular arcades of the splenic flexure were dissected, the number of vascular arches, and the origin and localization of its terminal anastomosis were recorded. The splenic flexure avascular space (SFAS) was defined as the avascular zone in the mesocolon delimited by the VEOP, middle colic artery, ascending branch of the left colic artery and the vascular arch of the splenic flexure nearest to the VEOP and was quantified as the distance between the VEOP and the most proximal arch RESULTS: The artery of Drummond was identified in 100% of the cadavers. In 5 of 27 (18%) Riolan's arch was present, and in 3 of 27 (11%) the Moskowitz artery was found. The mean distance from the VEOP to the artery of Moskowitz was 0.3 cm (SD 0.04). This vascular arch travelled from the origin of the middle colic artery to the distal third of the ascending branch of the left colic artery. The SFAS was greater (p = 0.001) in cadavers that only presented the artery of Drummond (mean 6.8 cm; SD 1.25) than in those with Riolan's arch (mean 4.5 cm; SD 0.5) CONCLUSIONS: In the medial approach for laparoscopic mobilization of the splenic flexure, when only one of the arches is present, the avascular area is an extensive and secure territory. If the artery of Moskowitz is present, the area is nonexistent and this would contraindicate the approach due to risk of iatrogenic bleeding. A radiological preoperatory study could be essential for accurate and safe surgery in this area.

Colon ischemia: Right-sided colon involvement has a different presentation, etiology and worse outcome. A large retrospective cohort study in histology proven patients

BACKGROUND

Colon ischemia (CI), is generally considered a non-occlusive mesenteric ischemia disorder that usually runs a benign course, but right-sided involvement (RCI) has been associated with worse outcome. The poor outcome of RCI has been associated with comorbidity, but more recently also with occlusions of the mesenteric arteries. We performed a retrospective analysis of a large cohort of CI-patients to assess differences in presentation, etiology, and comorbidity between right-sided colon ischemia (RCI) and non-right-sided colon ischemia (NRCI), and their relation to outcome.

METHODS

We performed a retrospective cohort study in two centers from 2000 to 2011 for CI and analyzed clinical presentation, etiology, treatment and outcome. Diagnosis was based on full colonoscopy and/or surgical findings and confirmed by histopathology.

RESULTS

239 patients were included (mean age 69, 52% female). RCI was found in 48% and NRCI in 52%. Patients with NRCI presented more often with rectal bleeding (87% vs. 45%; p<0.001). In RCI more nausea (58% vs. 39%; p=0.013), weight loss (56% vs. 19%; p<0.001), paralytic ileus (32% vs. 18%; p=0.018) and peritoneal signs (27% vs. 7%; p<0.001) was observed compared to NRCI. The cause of CI was more often idiopathic in NRCI (46% vs. 26%; p=0.002); an occlusive cause was seen more often in RCI (26.3 vs 2.4%, p<0.0001). RCI patients had longer hospital stay (15 vs. 8 days, p<0.001), need for surgery (61% vs. 34%, p<0.001), and trend toward higher 30-day in-hospital mortality (20% vs. 12%, p=0.084).

CONCLUSIONS

RCI ischemia has different etiology, presentation, and outcome. The series shows a high proportion of - treatable - vessel occlusion. It reinforces the advice to perform CT angiography in RCI as means to improve its poor outcome.

ESTES guidelines: acute mesenteric ischaemia

PURPOSE

Acute mesenteric ischaemia (AMI) accounts for about 1:1000 acute hospital admissions. Untreated, AMI will cause mesenteric infarction, intestinal necrosis, an overwhelming inflammatory response and death. Early intervention can halt and reverse this process leading to a full recovery, but the diagnosis of AMI is difficult and failure to recognize AMI before intestinal necrosis has developed is responsible for the high mortality of the disease. Early diagnosis and prompt treatment are the goals of modern therapy, but there are no randomized controlled trials to guide treatment and the published literature contains a high ratio of reviews to original data. Much of that data comes from case reports and often small, retrospective series with no clearly defined treatment criteria.

METHODS

A study group of the European Society for Trauma and Emergency Surgery (ESTES) was formed in 2013 with the aim of developing guidelines for the management of AMI. A comprehensive literature search was performed using the Medical Subject Heading (MeSH) thesaurus keywords "mesenteric ischaemia", "bowel ischaemia" and "bowel infarction". The bibliographies of relevant articles were screened for additional publications. After an initial systematic review of the literature by the whole group, a steering group formulated questions using a modified Delphi process. The evidence was then reviewed to answer these questions, and recommendations formulated and agreed by the whole group.

RESULTS

The resultant recommendations are presented in this paper.

CONCLUSIONS

The aim of these guidelines is to provide recommendations for practice that will lead to improved outcomes for patients.

MDCT in ischaemic colitis: how to define the aetiology and acute, subacute and chronic phase of damage in the emergency setting

Ischemic colitis (IC) is the most common vascular disorder of the gastrointestinal tract with a reported incidence of 6.1-44 cases/100,000 person years with confirmatory histopathology. However, the true incidence of IC poses some difficulty, and even vigilant clinicians with patients at high risk often miss the diagnosis, since clinical presentation is non-specific or could have a mild transient nature. Detection of IC results is crucial to plan the correct therapeutic approach and reduce the reported mortality rate (4-12%). Diagnosis of IC is based on a combination of clinical suspicion, radiological, endoscopic and histological findings. Some consider colonoscopy as a diagnostic test of choice; however, preparation is required and it is not without risk, above all in patients who are severely ill. There are two manifestations of vascular colonic insult: ischaemic and reperfusive. The first one occurs above all during ischaemic/non-occlusive mesenteric ischaemia; in this case, the colonic wall appears thinned with dilated lumen and fluid appears in the paracolic space. When reperfusion occurs, the large bowel wall appears thickened and stratified, because of subepithelial oedema and/or haemorrhage, with consequent lumen calibre reduction. Shaggy contour of the involved intestine and misty mesentery are associated with the pericolic fluid. The pericolic fluid results are a crucial finding for IC diagnosis since its evidence suggests the presence of an ongoing damage thus focusing the attention on other pathological aspects which could be otherwise misdiagnosed, such as thinned or thickened colonic wall. Moreover, the pericolic fluid may increase or decrease, depending on the evolution of the ischaemic damage, suggesting the decision of medical or surgical treatment. Radiologists should not forget the hypothesis of IC, being aware that multidetector CT could be sufficient to suggest the diagnosis of IC, allowing for early identification and grading definition, and in a short-term follow-up, discriminating patients who need urgent surgery from patients in whom medical treatment and follow-up can be proposed.

Update on Colon Ischemia: Recent Insights and Advances

Colon ischemia (CI) is the most common manifestation of ischemic injury to the gastrointestinal (GI) tract. This usually self-limited disease is being diagnosed more frequently, and the list of known causes is increasing. Local hypoperfusion and reperfusion injury are both thought to contribute to the disease process, which manifests with a wide spectrum of injury including reversible colopathy (subepithelial hemorrhage and edema), transient colitis, chronic colitis, stricture, gangrene, and fulminant universal colitis. The distribution is usually segmental with left-sided disease (e.g., inferior mesenteric artery distribution) being more frequently observed than right-sided involvement (e.g., superior mesenteric artery distribution). Any portion of the colon can be affected, but the anatomic distribution of CI recently has been shown to be associated with outcome. Patients with isolated-right colon ischemia (IRCI) have a different presentation and worse outcomes than other distributions of disease. Although somewhat variable depending on disease location, CI presents with cramping abdominal pains over the segment of colon involved followed by a short course of bloody diarrhea. Diagnosis is usually made clinically and is supported with serologic, radiologic, and colonoscopic findings. Colonoscopy is the most accurate diagnostic study. Most patients respond to conservative supportive therapy although some with more severe disease require antimicrobials and/or surgical intervention.

Features and Outcomes of Patients With Ischemia Isolated to the Right Side of the Colon When Accompanied or Followed by Acute Mesenteric Ischemia

BACKGROUND & AIMS

Patients with ischemia isolated to the right side of the colon (IRCI) frequently have poor outcomes. IRCI and acute mesenteric ischemia (AMI) are caused by reductions in blood supply from the superior mesenteric artery and its branches. We investigated a group of patients with IRCI associated with AMI that developed initially or shortly thereafter, and compared outcomes of patients with IRCI and AMI vs those with only IRCI.

METHODS

We performed a retrospective study of data collected from 313 consecutive patients with colonic ischemia who were hospitalized at Montefiore Medical Center in New York from 1998 through 2009. Based on colonoscopy, biopsy analyses, and surgery reports, we identified patients with IRCI with concurrent or proximately developing AMI (IRCI+AMI) and those with only IRCI. Demographics, evaluation, disease distribution, and outcome data were compared between groups.

RESULTS

Of 313 patients with colonic ischemia, 20.8% had IRCI; of these, 84.6% had only IRCI and 15.4% had IRCI+AMI. Chronic obstructive pulmonary disease was found more frequently in patients with IRCI+AMI (40.0%) than in patients with IRCI alone (12.7%; P < .05). At the time of IRCI diagnosis, mean levels of blood urea nitrogen were significantly higher in patients with IRCI+AMI than with IRCI alone (37.9 ± 14.4 mEq/L vs 26.4 ± 18.8 mEq/L; P < .05), as were mean white blood cell counts (20.3 ± 12.1 vs 12.7 ± 6.8 × 10(3)/μL; P < .01). A higher proportion of patients with IRCI+AMI underwent surgery than patients with only IRCI (100.0% vs 43.1%; P = .001), and 30-day mortality was higher among patients with IRCI+AMI (70.0% vs 14.5% for patients with only IRCI; P < .001).

CONCLUSIONS

Based on an analysis of 313 patients with colonic ischemia, patients with IRCI+AMI have even more severe disease than those with IRCI alone. Chronic obstructive pulmonary disease was observed more frequently in patients with IRCI+AMI. Patients with IRCI+AMI had increased levels of blood urea nitrogen and/or white blood cell counts. Patients with IRCI should undergo vascular imaging analyses immediately to detect AMI; patients without AMI should be monitored closely for its subsequent development.

Compression of the Celiac Artery by the Median Arcuate Ligament: Multidetector Computed Tomography Findings and Characteristics

Purpose

The prevalence of the celiac artery stenosis caused by median arcuate ligament (MAL) compression and its multidetector computed tomography (MDCT) characteristics were evaluated in patients who underwent abdominal MDCT procedures, retrospectively.

Methods

Totally 1121 patients who had abdominal MDCT with arterial phase or MDCT angiography of the abdominal aorta for various indications were analyzed for celiac artery compression by the MAL.

Results

Fifty (ie, 4.6%) patients showed typical MDCT features of MAL compression. Focal narrowing of the proximal celiac artery, a characteristic hooked appearance of the narrowed segment without calcification and atherosclerotic changes were diagnostic. Poststenotic dilatation was detected in 22 (44%) patients with MAL compression. The ratio of the stenosis of the celiac artery was between 35%-50% in 15 patients and 51%-80% in 35 patients. The gastroduodenal artery diameter of these patients was not significantly different from the asymptomatic control group.

Conclusion

MALS is an uncommon entity but it should be kept in mind in the presence of unexplained gastrointestinal symptoms. MDCT is a minimally invasive and plays a dominant role in the diagnosis of MAL compression especially with reformatted and 3-D reconstructed images.

Mesenteric stenosis, collaterals, and compensatory blood flow

BACKGROUND

The mesenteric circulation has an extensive collateral network. Therefore, stenosis in one or more mesenteric arteries does not necessarily lead to symptoms. The objective of this study was to determine the effect of collateral flow on celiac artery (CA) and superior mesenteric artery (SMA) duplex parameters.

METHODS

Between 1999 and 2007, a cohort of 228 patients analyzed for suspected chronic mesenteric syndrome was studied. Stenosis of the mesenteric vessels and collateral flow patterns were identified on angiography and categorized. The effect of stenosis in one mesenteric vessel and the presence of collaterals from the other unaffected vessel was examined in both the CA and SMA.

RESULTS

Stenosis of the CA resulted in a significantly higher peak systolic velocity (PSV) and end-diastolic velocity in the normal SMA without stenosis. This was also found for the CA without stenosis in the presence of a stenosis of the SMA. An incremental effect of the severity of the CA stenosis was found with a mean SMA PSV of 158 cm/s when normal and 259 cm/s when occluded. The presence of collaterals had a clear effect on duplex parameters of the angiographically normal SMA. In the presence of collaterals and a 70% CA stenosis, the PSV in the normal SMA was significantly higher (P = .025).

CONCLUSIONS

This study shows that stenosis in either the CA or SMA increases flow velocities in the other unaffected mesenteric artery. This increase was correlated with the presence of collaterals. Collaterals and stenoses in one of the mesenteric arteries may lead to mimicking or overgrading of stenosis in the other mesenteric artery.

Acute arterial mesenteric ischemia and reperfusion: Macroscopic and MRI findings, preliminary report

AIM: To explore the physiopathology and magnetic resonance imaging (MRI) findings in an animal model of acute arterial mesenteric ischemia (AAMI) with and without reperfusion.

METHODS: In this study, 8 adult Sprague-Dawley rats underwent superior mesenteric artery (SMA) ligation and were then randomly divided in two groups of 4. In group I, the ischemia was maintained for 8 h. In group II, 1-h after SMA occlusion, the ligation was removed by cutting the thread fixed on the back of the animal, and reperfusion was monitored for 8 h. MRI was performed using a 7-T system.

RESULTS: We found that, in the case of AAMI without reperfusion, spastic reflex ileus, hypotonic reflex ileus, free abdominal fluid and bowel wall thinning are present from the second hour, and bowel wall hyperintensity in T2-W sequences are present from the fourth hour. The reperfusion model shows the presence of early bowel wall hyperintensity in T2-W sequences after 1 h and bowel wall thickening from the second hour.

CONCLUSION: Our study has shown that MRI can assess pathological changes that occur in the small bowel and distinguish between the presence and absence of reperfusion after induced acute arterial ischemia.

A review of ischemic colitis: is our clinical recognition and management adequate?

Ischemic colitis is a common cause of hospital admissions; however it is frequently confused intellectually with mesenteric ischemia and often misdiagnosed as infectious diarrhea or Clostridium difficile colitis. Ischemic colitis is caused by non-occlusive insult to the small vessels supplying the colon without a clear precipitating factor. It is more common in females and in patients above 60 years of age. The classic presentation includes sudden onset of lower abdominal pain followed by the urge to defecate and bloody diarrhea. Focal right-sided ischemic colitis has more pain and a worse prognosis. Choosing the correct diagnostic studies is challenging and requires proficient knowledge of the disease. Management is usually conservative, however around 10-20% of the patients will require surgery. Acute ischemic colitis usually resolves; nevertheless some patients may develop chronic segmental colitis or a stricture. One ischemic colitis caveat is that it may be the first sign of undiagnosed cardiac disease. A firm grasp on this common yet little discussed condition is valuable to a gastrointestinal consultant and hospitalist alike.

Ischemic bowel syndromes

Atherosclerotic vascular disease involving the mesenteric arteries occurs frequently in the elderly population. Although the prevalence of ischemic bowel disease is difficult to determine, acute mesenteric ischemia (AMI) has been reported to cause in 1 in 1000 hospital admissions, whereas chronic mesenteric ischemia (CMI) is estimated to affect 1 in 100,000 individuals. Mesenteric ischemia generally manifests in its chronic form as postprandial abdominal pain resulting in significant weight loss, and in its acute form as an abrupt development of abdominal pain, lower gastrointestinal bleeding, and subsequent intestinal necrosis. This article discusses the cause, clinical manifestations, diagnosis, and management of AMI and CMI.

Ischemic colitis and large bowel infarction: A case report

Ischemic bowel disease results from an acute or chronic drop in the blood supply to the bowel and may have various clinical presentations, such as intestinal angina, ischemic colitis or intestinal infarction. Elderly patients with systemic atherosclerosis who are symptomatic for the disease in two or more vascular beds have multiple comorbidities and are particularly at risk. The clinical evolution and outcome of this disease are difficult to predict because of its pleomorphic aspects and the general lack of statistical data. In this paper, we present the case of a patient who was monitored in our unit for six years. For this patient, we encountered iterative changes in the clinical pattern, beginning with chronic “intestinal angina” and finishing with signs of acute mesenteric ischemia after an episode of ischemic colitis. This evolution is particularly rare in clinical practice, and the case is instructive because it raises discussions about the natural history of the condition and the therapeutic decisions that should be made at every stage of the disease. An important lesson is that ischemic bowel disease should always be considered in patients who have multiple risk factors for atherosclerosis and have experienced recurrent “indistinct” abdominal symptoms. In these cases, aggressive investigation and therapeutic decisions must be taken whenever possible. Despite an absence of standardized protocols, angiographic evaluation and revascularization procedures have beneficial outcomes. Current advances in endovascular therapy, such as percutaneous transluminal angioplasty with stenting, should be increasingly used in patients with chronic mesenteric ischemia. Such therapy can avoid the risks that are associated with open repair. However, technical difficulties, especially in severe stenotic lesions, frequently occur.

Predictors of severity in ischaemic colitis

PURPOSE

Ischaemic colitis (IC) is an inadequate perfusion leading to potentially life-threatening colonic inflammation. The aim was to identify patient characteristics that predict severity in biopsy-confirmed IC.

METHODS

A retrospective study of consecutive patients admitted with a robust diagnosis of IC over a 5-year period was performed. As IC is often misdiagnosed, strict inclusion criteria including supporting histopathology, exclusion of inflammatory bowel disease, absence of recent antibiotics or negative stool sampling with testing for Clostridium difficile were adhered to. Due to differing pathophysiology involved, patients suffering IC due to injury to colonic perfusion from vascular procedures or tumours were also excluded. Patients were divided by outcomes into a severe IC group including those that needed surgery or suffered mortality and a non-severe IC group that included patients managed medically with good evolution during their index admission. Patient characteristics were analysed to identify statistically significant predictors of severity (p < 0.05).

RESULTS

Thirty-two patients (11 males, 21 females; mean age 72.5) met the inclusion criteria. Medical management was adopted in 23 patients with a single mortality (4.3%). Nine patients were managed surgically with two mortalities (22.2%), giving an overall mortality of 9.4% and a severe IC group consisting of ten patients. Significant prognostic predictors of severity included: right-sided IC (p = 0.0002), guarding (p = 0.001), lack of bleeding per rectum (p = 0.005) and chronic constipation (p = 0.02).

CONCLUSIONS

The majority of patients with IC can be managed conservatively. Right-sided IC, guarding, lack of bleeding per rectum and chronic constipation are associated with severe IC.

Mesenteric venous thrombosis

First differentiated from arterial causes of acute mesenteric ischemia 75 years ago, acute mesenteric venous thrombosis (MVT) is an uncommon disorder with non-specific signs and symptoms, the diagnosis of which requires a high index of suspicion. The location, extent, and rapidity of thrombus formation determine whether intestinal infarction ensues. Etiologies, when identified, usually can be separated into local intra-abdominal factors and inherited or acquired hypercoagulable states. The diagnosis is most often made by contrast-enhanced computed tomography, though angiography and exploratory surgery still have important diagnostic as well as therapeutic roles. Anticoagulation prevents clot propagation and is associated with decreased recurrence and mortality. Thrombectomy and thrombolysis may preserve questionably viable bowel and should be considered under certain circumstances. Evidence of infarction mandates surgery and resection whenever feasible. Although its mortality rate has fallen over time, acute MVT remains a life-threatening condition requiring rapid diagnosis and aggressive management. Chronic MVT may manifest with complications of portal hypertension or may be diagnosed incidentally by noninvasive imaging. Management of chronic MVT is directed against variceal hemorrhage and includes anticoagulation when appropriate; mortality is largely dependent on the underlying risk factor.

Intestinal ischemia/reperfusion: microcirculatory pathology and functional consequences

BACKGROUND

Intestinal ischemia and reperfusion (I/R) is a challenging and life-threatening clinical problem with diverse causes. The delay in diagnosis and treatment contributes to the continued high in-hospital mortality rate.

RESULTS

Experimental research during the last decades could demonstrate that microcirculatory dysfunctions are determinants for the manifestation and propagation of intestinal I/R injury. Key features are nutritive perfusion failure, inflammatory cell response, mediator surge and breakdown of the epithelial barrier function with bacterial translocation, and development of a systemic inflammatory response. This review provides novel insight into the basic mechanisms of damaged intestinal microcirculation and covers therapeutic targets to attenuate intestinal I/R injury.

CONCLUSION

The opportunity now exists to apply this insight into the translation of experimental data to clinical trial-based research. Understanding the basic events triggered by intestinal I/R may offer new diagnostic and therapeutic options in order to achieve improved outcome of patients with intestinal I/R injury.

Colon ischemia: recent insights and advances

Ischemic colitis is the most common manifestation of ischemic injury to the gastrointestinal tract, and the variety of defined causes is increasing. Local hypoperfusion and reperfusion injury are both thought to contribute to the disease process, which manifests with a wide spectrum of injury including reversible colopathy (subepithelial hemorrhage and edema), transient colitis, chronic colitis, stricture, gangrene, and fulminant universal colitis. The distribution is typically segmental. Older studies showed that any portion of the colon can be involved; recently, it was established that the site of involvement and prognosis can be correlated. In particular, isolated involvement of the right side of the colon was shown to have a different presentation and worse outcome than ischemic colitis involving other segments. Diagnosis is usually made clinically and supported by radiologic imaging and colonoscopic evaluation. Most patients respond to conservative supportive therapy, although some with severe disease require surgical intervention.

Anatomic patterns, patient characteristics, and clinical outcomes in ischemic colitis: a study of 313 cases supported by histology

OBJECTIVES

Previous reports on the anatomic portions of colon involved in cases of supposed ischemic colitis (IC) have been limited by the absence of confirmation of the true nature of the disease. This is the first anatomic study to define the patterns of colon involvement in which only cases with biopsy-proven or -compatible IC and in which the entire colon had been visualized at surgery or at colonoscopy were included. The aims of this study were to re-examine patterns of colonic involvement in IC using only cases in which the diagnosis was biopsy proven or compatible, and to examine the clinical features and outcomes with regard to the segments of colon involved.

METHODS

A retrospective study was undertaken of patients with IC who were hospitalized at Montefiore Medical Center from 1998 to 2009. Patients were identified using computerized searches of ICD-9 (International Classification of Diseases, ninth revision) codes for colon ischemia, and patterns of colon involvement were then tabulated and categorized into five major groups: right colon, transverse colon, left colon, distal colon, and pancolon involvement. Patterns were classified based on the most proximal location of injury. Major anatomic patterns were then subcategorized into more specific segments of involvement. Only biopsy-proven or -compatible cases of IC in which the entire colon had been visualized at surgery or at colonoscopy were used in this study.

RESULTS

A total of 313 cases of biopsy-proven or -compatible IC were identified. Patterns and frequencies of involvement were: right colon, 25.2%; transverse colon, 10.2%; left colon, 32.6%; distal colon, 24.6%; and pancolon, 7.3%. Compared with all other patterns of IC, the right colon pattern was more likely to be associated with coronary artery disease (39.2 vs. 21.4%) or end-stage kidney disease requiring dialysis (20.3 vs. 7.7%), a longer hospitalization (median stay, 10 vs. 6 days), a greater need for surgery (44.3 vs. 11.5%), and the highest mortality rate (20.3 vs. 9%). Patients with a left colon pattern were less likely to be operated upon, and had a shorter length of stay than any other pattern of IC. Hyperthyroidism, stroke, and chronic obstructive pulmonary disease (COPD) were statistically significant independent predictors of mortality.

CONCLUSIONS

IC is typically a segmental disease, flanked by normal colon on either side of the affected area. Comorbid disease associations and severity of disease as reflected by length of hospitalization, need for surgery, and mortality vary with the segment involved. IC isolated to the right side of the colon is a more severe disease than IC affecting any other segment of colon.

Drug-induced Injury of the Gastrointestinal Tract

The effects of drugs on the gastrointestinal tract are diverse and depend on numerous factors. Diagnosis is centered on histologic findings, with mostly nonspecific patterns of injury that must be interpreted in the correct clinical context. Nonsteroidal antiinflammatory drugs are a common cause of drug-induced gastrointestinal injury, with effects primarily in the gastric mucosa but also throughout the gastrointestinal tract. Another common class of drugs causing a variety of pathologic findings in the gut is chemotherapeutic agents. This article discusses the differential diagnosis of the various patterns of injury, including ischemic damage, and the histologic findings specific for certain drugs.

Fulminant nonocclusive mesenteric ischemia just after hip arthroplasty

Nonocclusive mesenteric ischemia (NOMI) is not a rare clinical entity in intensive medicine, and it can be a consequence of several clinical or surgical situations. This pathology results from reduced intestinal microvascular blood supply associated with an acute inflammatory process, culminating with bowel necrosis. This is a case on a female patient who developed immediate postsurgical NOMI following hip arthroplasty and died. Since diagnosis of this potentially fatal condition remains a dilemma, NOMI should always be considered an eventual postoperative complication in high-risk surgical patients such as elderly individuals with previous history of nicotine abuse, congestive heart failure, and essential hypertension. The present paper highlights the importance of early diagnosis and prompt adequate treatment of NOMI in subjects with diminished cardiac output and severe abdominal pain.

Anesthetic management of acute mesenteric ischemia in elderly patients

Ischemic insult to the splanchnic vasculature can jeopardize bowel viability and lead to devastating consequences, including bowel necrosis and gangrene. Although acute mesenteric ischemia (AMI) may occur at any age, the elderly are most commonly affected due to their higher incidence of underlying systemic pathology, most notably atherosclerotic cardiovascular disease. Treatment options include pharmacology-based actions, endovascular, and surgical interventions. AMI remains a life-threatening condition with a mortality rate of 60% to 80%, especially if intestinal infarction has occurred and surgical intervention becomes emergent. Early recognition and an aggressive therapeutic approach are essential if the usually poor outcome is to be improved. Anesthetic management is complex and must account for comorbid disease as well as the patient's presumptive acute deterioration. Blood pressure support typically involves careful, but often massive, fluid resuscitation and may also additionally require pharmacologic support.

Spectrum of CT findings in patients with atrial fibrillation and nontraumatic acute abdomen

OBJECTIVE

The purpose of our study was to review the wide spectrum of pertinent CT findings in patients with acute nontraumatic abdominal pain in the setting of atrial fibrillation.

CONCLUSION

Underlying embolic or hemorrhagic complications are common in patients with acute nontraumatic abdominal pain in the setting of atrial fibrillation and can be accurately seen on CT.

Small Bowel Ischemia in a Sickle Cell Patient

We report a case of small bowel ischemia secondary to sickle cell disease. Acute bowel ischemia is an uncommon presentation of patients with sickle cell disease. Historically, only a handful of cases have been reported. We also provide a summary of the literature relevant to sickle cell patients with acute bowel ischemia.

Acute mesenteric ischaemia: facts and perspectives

Acute mesenteric ischaemia is a catastrophic abdominal emergency with an extremely high mortality rate. This article discusses the aetiology, diagnosis and treatment of acute mesenteric ischaemia with emphasis on avoidance of common errors that contribute to the poor outcome inherent to this condition.

Imaging of acute mesenteric ischemia using multidetector CT and CT angiography in a porcine model

Acute mesenteric ischemia, a frequently lethal disease, requires prompt diagnosis and intervention for favorable clinical outcomes. This goal remains elusive due, in part, to lack of a noninvasive and accurate imaging study. Traditional angiography is the diagnostic gold standard but is invasive and costly. Computed tomography (CT) is readily available and noninvasive but has shown variable success in diagnosing this disease. The faster scanning time of multidetector row CT (M.D.CT) greatly facilitates the use of CT angiography (CTA) in the clinical setting. We sought to determine whether M.D.CT-CTA could accurately demonstrate vascular anatomy and capture the earliest stages of mesenteric ischemia in a porcine model. Pigs underwent embolization of branches of the superior mesenteric artery, then imaging by M.D.CT-CTA with three-dimensional reconstruction protocols. After scanning, diseased bowel segments were surgically resected and pathologically examined. Multidetector row CT and CT angiography reliably defined normal and occluded mesenteric vessels in the pig. It detected early changes of ischemia including poor arterial enhancement and venous dilatation, which were seen in all ischemic animals. The radiographic findings--compared with pathologic diagnoses-- predicted ischemia, with a positive predictive value of 92%. These results indicate that M.D.CT-CTA holds great promise for the early detection necessary for successful treatment of acute mesenteric ischemia.

The meandering mesenteric artery: a historic review and surgical implications

PURPOSE

The aim of this study was to review the literature regarding collateral mesenteric circulation with emphasis on the mesenteric meandering artery (of Moskowitz). Standard vascular embryology and anatomy are described as are the collateral mesenteric vessels that can develop with arterial stenosis or occlusion. A discussion on the correct usage of terms for describing mesenteric collateral vessels follows.

METHODS

We undertook review of the historical literature to discuss the surgical implications of the meandering mesenteric artery.

RESULTS

Despite a long history of study by anatomists and surgeons, confusion still persists regarding both the number and correct descriptive terminology of the collateral mesenteric vessels.

CONCLUSIONS

The use of the vague historic term "arc of Riolan" should be discarded for the more precise term "meandering mesenteric artery." The meandering mesenteric artery should routinely be preserved in all surgical procedures, to include resection for cancer, given its critical function in providing collateral mesenteric circulation. Further evaluation in the asymptomatic patient, however, is unnecessary.

Review article: diagnosis and management of mesenteric ischaemia with an emphasis on pharmacotherapy

Mesenteric ischaemia results from decreased blood flow to the bowel, causing cellular injury from lack of oxygen and nutrients. Acute mesenteric ischaemia (AMI) is an uncommon disorder with high morbidity and mortality, but outcomes are improved with prompt recognition and aggressive treatment. Five subgroups of AMI have been identified, with superior mesenteric artery embolism (SMAE) the most common. Older age and cardiovascular disease are common risk factors for AMI, excepting acute mesenteric venous thrombosis (AMVT), which affects younger patients with hypercoaguable states. AMI is characterized by sudden onset of abdominal pain; a benign abdominal exam may be observed prior to bowel infarction. Conventional angiography and more recently, computed tomography angiography, are the cornerstones of diagnosis. Correction of predisposing conditions, volume resuscitation and antibiotic treatment are standard treatments for AMI, and surgery is mandated in the setting of peritoneal signs. Intra-arterial vasodilators are used routinely in the treatment of non-occlusive mesenteric ischaemia (NOMI) and also are advocated in the treatment of occlusive AMI to decrease associated vasospasm. Thrombolytics have been used on a limited basis to treat occlusive AMI. A variety of agents have been studied in animal models to treat reperfusion injury, which sometimes can be more harmful than ischaemic injury. Chronic mesenteric ischaemia (CMI) usually is caused by severe obstructive atherosclerotic disease of two or more splanchnic vessels, presents with post-prandial pain and weight loss, and is treated by either surgical revascularization or percutaneous angioplasty and stenting.

Acute small bowel ischemia: CT imaging findings

Small bowel ischemia is a disorder related to a variety of conditions resulting in interruption or reduction of the blood supply of the small intestine. It may present with various clinical and radiologic manifestations, and ranges pathologically from localized transient ischemia to catastrophic necrosis of the intestinal tract. The primary causes of insufficient blood flow to the small intestine are various and include thromboembolism (50% of cases), nonocclusive causes, bowel obstruction, neoplasms, vasculitis, abdominal inflammatory conditions, trauma, chemotherapy, radiation, and corrosive injury. Computed tomography (CT) can demonstrate changes because of ischemic bowel accurately, may be helpful in determining the primary cause of ischemia, and can demonstrate important coexistent findings or complications. However, common CT findings in acute small bowel ischemia are not specific and, therefore, it is often a combination of clinical, laboratory and radiologic signs that may lead to a correct diagnosis. Understanding the pathogenesis of various conditions leading to mesenteric ischemia and being familiar with the spectrum of diagnostic CT signs may help the radiologist recognize ischemic small bowel disease and avoid delayed diagnosis. The aim of this article is to provide a review of the pathogenesis and various causes of acute small bowel ischemia and to demonstrate the contribution of CT in the diagnosis of this complex disease.

CT in acute mesenteric ischaemia

Enhanced computed tomography (CT) is frequently performed for possible bowel ischaemia. It has the distinct advantage of possible detection of the causes of ischaemia. Radiologists therefore need to be familiar with the spectrum of diagnostic CT signs. We present the CT imaging findings in surgically proven cases of small bowel ischaemia. In addition to signs pertaining to the underlying aetiological pathology, bowel dilatation, bowel wall thickening, mural gas, occlusion of mesenteric vessels, ascites and infarct of other abdominal organs were observed.

Intravenous iloprost increases mesenteric blood flow in experimental acute nonocclusive mesenteric ischemia

OBJECTIVE

To evaluate the effect of an intravenously administered synthetic epoprostenol analog, iloprost, in nonocclusive acute mesenteric ischemia induced by cardiac tamponade.

DESIGN

Prospective, randomized, controlled experimental study.

SETTING

Animal research laboratory at a university medical center.

SUBJECTS

Ten Yorkshire pigs (weight range, 20-25 kg).

INTERVENTIONS

Nonocclusive acute mesenteric ischemia was induced by pericardial tamponade. Pigs were randomized to receive either a low-dose, continuous intravenous infusion of iloprost (0.075 microg/kg/min) or an equivalent volume of normal saline to serve as the control. Infusion of iloprost or saline was continued after pericardial tamponade was reversed.

METHODS

Ten anesthetized and ventilated pigs underwent laparotomy and thoracotomy. A pulmonary artery catheter was inserted, a magnetic flow probe was positioned around the superior mesenteric artery (SMA), and cannulation of the pericardial space was performed. Pericardial tamponade was induced by injecting 5% dextrose in water into the pericardial space until blood flow in the superior mesenteric artery decreased to half of baseline. After 60 mins, animals received either a continuous intravenous infusion of iloprost at 0.075 microg/kg/min (n = 6) or an equal volume of normal saline (n = 4) for 60 mins. Pericardial fluid was then removed, and iloprost or normal saline infusion was continued for another 60 mins.

MEASUREMENTS

Heart rate, blood pressure, cardiac output, oxygen delivery, oxygen consumption, SMA blood flow, ileal Pco2, ileal intramucosal pH, and serum lactate levels of mixed venous blood and mesenteric venous blood were recorded at baseline, after pericardial tamponade was induced, during the iloprost or normal saline infusion with pericardial tamponade, and after removal of pericardial fluid (reperfusion period).

RESULTS

Iloprost infusion increased SMA blood flow by 60% in this model of nonocclusive mesenteric ischemia (from 168 +/- 41 to 269 +/- 76 mL/min; p <.05). The effect of iloprost infusion was more prominent after the tamponade (422 +/- 87 mL/min in the iloprost group vs. 232 +/- 111 mL/min in the control group; p <.05). Increased mesenteric perfusion decreased intestinal mucosal hypercarbia, leading to improvement of intramucosal pH.

Radiologic diagnosis and treatment of gastrointestinal hemorrhage and ischemia

Major breakthroughs in catheter, guidewire, and other angiographic equipment currently allow interventional radiologists to diagnose massive life-threatening upper and lower GI hemorrhage and to stop the bleeding safely and effectively using superselective catheterization and microcoil embolization. Similarly, the interventional radiologist can treat acute intestinal ischemia safely and effectively with selective catheterization and papaverine administration and treat chronic mesenteric ischemia by percutaneous angioplasty and stent placement. A multidisciplinary approach, including the gastroenterologist, radiologist, and surgeon, is critical in managing GI bleeding and intestinal ischemia, particularly in patients at high risk or presenting as diagnostic dilemmas.

Multi-detector row CT of mesenteric ischemia: can it be done?

Mesenteric ischemia is a complicated disorder whose prevalence in the United States is increasing as the population ages. It is often difficult to diagnose, both clinically and radiologically. In the past, computed tomography (CT) has allowed only limited success in the early detection of ischemia. However, with the introduction of multi-detector row CT and three-dimensional (3D) imaging, it is now possible to perform a detailed CT examination of the small bowel and mesenteric vessels. Multi-detector row CT allows routine studies to be performed much faster than with single-detector CT scanners and makes available new applications, especially in the field of CT angiography. Its increased speed and narrower collimation, coupled with the use of water as an oral contrast agent, improve visualization of the bowel wall and mesenteric vasculature. Multi-detector row CT with 3D reformatting may improve the ability to make an early diagnosis and identify the cause of disease in patients with suspected acute or chronic mesenteric ischemia. In many cases, this examination has eliminated the need for additional imaging studies such as Doppler ultrasonography or angiography. Further investigation will be needed to determine the scope of the utility of multi-detector row CT in this clinical setting.

Intestinal (mesenteric) vasculopathy. I. Acute superior mesenteric arteriopathy and venopathy

Intestinal vasculopathy is not rare, comprising about 1 per 1000 hospital admissions. Primary mesenteric vasculopathy causes cardiovascular disease, whereas secondary mesenteric ischemia causes extrinsic vascular compression or vascular trauma. Acute superior mesenteric arteriopathy is caused by a mesenteric embolus, thrombus, or vasospasm (i.e., nonocclusive vasculopathy). Acute superior mesenteric venopathy is caused by a thrombus, which is often associated with a hypercoagulopathy. The clinical presentation of both diseases is often subtle and nonspecific at an early stage and becomes overt and specific only when advanced and severe, when ischemia progresses to necrosis. The mortality of acute superior mesenteric arteriopathy is still very high, whereas superior mesenteric venopathy is less rapidly progressive and has a lower, but still significant, mortality. Early diagnosis and aggressive therapy significantly reduces the mortality of these life-threatening diseases.