Diagnostic tests for intestinal ischemia

A Rare Case of Superior Mesenteric Artery Thrombosis With Gangrenous Bowel in a Patient With Mitral Valve Replacement in a Hypocoagulable State

Acute thromboembolism of the superior mesenteric artery (SMA) causing mesenteric ischemia has a grave prognosis with high mortality rates. Its rarity and non-specific symptoms often lead to delayed diagnosis and increased morbidity. Early signs can include pain out of proportion to physical findings, with abdominal distension, tenderness, and guarding appearing only in later stages when bowel necrosis has occurred. Leukocytosis, metabolic acidosis, and lactic acidosis may also be present. Immediate treatment through radiological investigation and restoration of blood flow can be through interventional radiology or surgery. In cases of infarction, resection and exteriorization are needed. Patients with mechanical mitral valves, even on blood thinners, remain at risk for thromboembolism and may benefit from novel oral anticoagulants requiring less frequent monitoring. Regular monitoring of prothrombin time and international normalized ratio (INR) is essential for those on warfarin, as drugs and dietary changes (eating green leafy vegetables) can significantly affect INR levels. Early suspicion and prompt treatment are vital for improving outcomes.

Superior Mesenteric Artery Thrombosis in COVID-19-Positive Patients: A Rare Coincidence

Since the start of the SARS-CoV-2 pandemic, which is otherwise known as the worldwide coronavirus disease, 2019, has had a well-established pro-thrombotic character. Patients often first exhibit respiratory symptoms, and those whose severity increases eventually develop acute hypoxic respiratory failure. The systemic hypercoagulable condition and arterial/venous thrombosis related to COVID-19 have a poor prognosis. Even though superior mesenteric artery (SMA) thrombosis and acute mesenteric ischemia (AMI) are uncommon, they frequently coexist with fatal gastrointestinal (GI) pathologies that necessitate prompt diagnosis and treatment by the doctor. This calls for more research into the effects of anticoagulation therapy in COVID-19-positive patients. The main treatment aims for this condition are early detection, surgical or intravascular re-establishment of blood supply to the ischemic bowel, and surgical resection. The study aimed to see the outcome after surgical intervention in patients with SMA thrombosis post-COVID-19 infection. This study was from March 2021 to January 2022, with a sample size of 5 patients with SMA thrombosis, which was confirmed on contrast-enhanced computed tomography (CECT) abdomen and pelvis with angiography. The patients underwent exploratory laparotomy. Bowel resection and anastomosis were performed in three individuals; bowel resection and stoma placement were performed in two patients. Doctors have significant clinical challenges as a result of the thromboembolic manifestations of the unexpected and deadly nature of the virus, such as AMI. The high morbidity and mortality associated with AMI calls for further study on prophylactic anticoagulation therapy in COVID-19-positive individuals.

Prediction of need for bowel resection in acute superior mesenteric artery occlusion: A retrospective study of 48 Japanese patients

Aim

This study aimed to predict cases of acute superior mesenteric artery (SMA) occlusion requiring bowel resection using occlusion site and time from symptom onset to diagnosis at five Japanese institutions. Advances in imaging, endovascular treatment, and perioperative management have improved the clinical outcomes of patients with acute SMA occlusion; however, in clinical practice it remains difficult to effectively determine patients requiring bowel resection.

Methods

We retrospectively analyzed the data of 48 patients (mean age: 82.5 y; male: 37.5%) diagnosed with acute SMA occlusion between June 2009 and August 2018. Background data of patients who required and did not require bowel resection were compared. A multivariable predictive model was developed using the time from symptom onset to diagnosis and whether SMA occlusion was proximal, including the origin of the middle colic artery.

Results

Fifteen patients (31.3%) died during the hospital stay. Atrial fibrillation (83.3%) was the most common comorbidity. The median time from symptom onset to diagnosis was 13.0 (interquartile range, 4.75-24.0) h. Laparotomy, bowel resection, and thrombus embolectomy were performed in 41 (85.4%), 26 (54.2%), and 21 (43.8%) patients, respectively. A logistic regression model achieved 78.6% sensitivity in predicting cases not requiring bowel resection. Proximal occlusion was significantly associated with the requirement for bowel resection (P = .039).

Conclusion

The time from symptom onset to diagnosis and occlusion site contributed to high sensitivity in determining the need for bowel resection in patients with acute SMA occlusion. Further prospective studies are warranted to investigate the clinical impact of this model.

Fulminant Ischemic Pancolitis: A Severe Variant of Ischemic Colitis

We present the case of a 75-year-old female with abdominal pain and a sudden change in mental status. She progressed rapidly with manifestations of acidosis without episodes of bloody bowel movements or diarrhea. The patient underwent emergent exploratory laparotomy, and a diagnosis of fulminant ischemic pancolitis was made with visual confirmation of infarcted colon from cecum to proximal rectum leading to subtotal colectomy and ileostomy. Postoperatively, the patient showed improved acidosis and mental status; unfortunately, over the subsequent days, the patient declined and was transferred to hospice and palliative care.

Diagnosis biomarkers in acute intestinal ischemic injury: so close, yet so far

Acute intestinal ischemic injury (i3) is a life-threatening condition with disastrous prognosis, which is currently difficult to diagnose at the early stages of the disease; a rapid diagnosis is mandatory to avoid irreversible ischemia, extensive bowel resection, sepsis and death. The overlapping protein expression of liver and gut related to the complex physiopathology of the disease, the heterogeneity of the disease and its relative rarity could explain the lack of a useful early biochemical marker of i3. Apart from non-specific biological markers of thrombosis, hypoxia inflammation, and infection, several more specific biomarkers in relation with the gut barrier dysfunction, the villi injury and the enterocyte mass have been used in the diagnosis of acute i3. It includes particularly D-lactate, intestinal fatty acid-binding protein (FABP) and citrulline. Herein, we will discuss leading publications concerning these historical markers that point out the main limitations reagrding their use in routine clinical practice. We will also introduce the first and limited results arising from omic studies, underlying the remaining effort that needs to be done in the field of acute i3 biological diagnosis, which remains a challenge.

Combination of diagnostic laparoscopy and intraoperative indocyanine green fluorescence angiography for the early detection of intestinal ischemia not detectable at CT scan

INTRODUCTION

Acute mesenteric ischemia is the most severe gastrointestinal complication of acute aortic dissection. The timing of diagnosis is of major importance, in fact the recognition of acute mesenteric ischemia often occurs too late due to the presence of unspecific symptoms and lack of reliable exams. Recently, indocyanine green fluorescence angiography has been adopted in order to measure blood perfusion and microcirculation.

PRESENTATION OF CASE

We decided to perform a diagnostic laparoscopy with the support of intra-operative near-infrared indocyanine green fluorescence angiography, in order to detect an initial intestinal ischemia in a 68-year-old patient previously treated with a TEVAR procedure for a type-B aortic dissection. The fluorescence system demonstrated an hypoperfused area in the ascending colon, therefore an ileocholic resection was thus performed. Opening the operatory specimen, the mucosa of the colon appeared totally ischemic, whilst the serosa was normal.

DISCUSSION

When ischemia occurs, the oxygen supply is interrupted, hence the necrosis of the enteral mucosa occurs within 3h, whilst the necrosis of the full thickness of the bowel wall occurs within 6h. A diagnosis during these "golden hours" is of major importance for a successful treatment.

CONCLUSION

The combination of laparoscopy and UV light and fluorescein dye should be considered as an invaluable diagnostic procedure for the diagnosis of early stage acute bowel ischemia which is not visible at instrumental examinations nor with diagnostic laparoscopy.

Vascular anatomy of the small intestine-a comparative anatomic study on humans and pigs

BACKGROUND

Porcine models are well established for studying intestinal anastomotic healing. In this study, we aimed to clarify the anatomic differences between human and porcine small intestines. Additionally, we investigated the influences of longitudinal and circular sutures on human small intestine perfusion.

METHODS

Intestines were obtained from human cadavers (n = 8; small intestine, n = 51) and from pigs (n = 10; small intestine, n = 60). Vascularization was visualized with mennige gelatin perfusion and high-resolution mammography. Endothelial cell density was analyzed with immunohistochemistry and factor VIII antibodies. We also investigated the influence of suture techniques (circular anastomoses, n = 19; longitudinal sutures, n = 15) on vascular perfusion.

RESULTS

Only human samples showed branching of mesenteric vessels. Compared to the pig, human vessels showed closer connections at the entrance to the bowel wall (p = 0.045) and higher numbers of intramural anastomoses (p < 0.001). Porcine main vessels formed in multifilament-like vessel bundles and displayed few intramural vessel anastomoses. Circular anastomoses induced a circular perfusion defect at the bowel wall; longitudinal anastomoses induced significantly smaller perfusion defects (p < 0.001). Both species showed higher vascular density in the jejunum than in the ileum (p < 0.001). Human samples showed similar vascular density within the jejunum (p = 0.583) and higher density in the ileum (p < 0.001) compared to pig samples.

CONCLUSION

The results showed significant differences between human and porcine intestines. The porcine model remains the standard for studies on anastomotic healing because it is currently the only viable model for studying anastomosis and wound healing. Nevertheless, scientific interpretations must consider the anatomic differences between humans and porcine intestines.

Acute Mesenteric Ischaemia

Acute mesenteric ischaemia (AMI) is a surgical emergency, and has a high mortality. The term AMI covers arterial embolism, arterial thrombosis, non-occlusive mesenteric ischaemia and venous thrombosis which all lead to ischaemia/reperfusion syndrome of the bowel. Multi-detector row helical CT (MDCT) technology has dramatically improved the performance of CT by allowing rapid volumetric data acquisition to provide increased resolution, leading to better identification of the site, level and cause of ischaemia. CT angiography for diagnosing mesenteric ischaemia is now highly sensitive and specific, and should be used as first line when AMI is suspected. The aim of management is to restore intestinal blood flow in a timely manner. Therapeutic decisions are based on the presence of peritonitis, the presence of irreversible ischaemia or infarcted segments of the bowel, the general condition of the patient and the pathophysiological process underlying the ischaemia. AMI remains a challenging condition with high mortality. There is a need for good general surgical cover on the intensive care unit, with continuing care and clinical review by experienced senior surgeons with an interest in this condition.

Management of ischemic colitis

Ischemic colitis is a commonly misunderstood clinical condition. Although the colon is the most common region of ischemia in the gastrointestinal tract, many surgeons have difficulty with diagnosis and treatment of ischemic colitis. The process can occur from either occlusive vascular disease or nonocclusive disease, and can be gangrenous or nongangrenous. Differentiating gangrenous from nongangrenous disease can be a difficult clinical challenge as both sets of patients generally present with abdominal pain and bloody diarrhea. Although the majority of patients have transient ischemia with nongangrenous colitis that can be successfully managed nonoperatively, prompt recognition and surgical intervention is critical in patients with gangrenous colitis. In this article, the diagnosis and treatment of ischemic colitis is reviewed with emphasis on a systematic, evidence-based approach to management.

Gastro-intestinal vascular emergencies

Gastro-Intestinal Vascular Emergencies include all digestive ischaemic injuries related to acute or chronic vascular and/or haemodynamic diseases. Gastro-intestinal ischaemic injuries can be occlusive or non-occlusive, arterial or venous, localized or generalized, superficial or transmural and share the risks of infarction, organ failure and death. The diagnosis must be suspected, at the initial presentation of any sudden, continuous and unusual abdominal pain, contrasting with normal physical examination. Risk factors are often unknown at presentation and no biomarker is currently available. The diagnosis is confirmed by abdominal computed tomography angiography identifying intestinal ischaemic injury, either with vascular occlusion or in a context of low flow. Recent knowledge in the pathophysiology of acute mesenteric ischaemia, clinical experience and existing recommendations have generated a multimodal and multidisciplinary management strategy. Based on the gastro-intestinal viability around a simple algorithm, and coordinated by gastroenterologists, the dual aim is to avoid large intestinal resections and death.

How to differentiate spontaneous intramural intestinal hemorrhage from acute mesenteric ischemia

OBJECTS

The purpose of our study was to assess the diagnostic values of laboratory tests to differentiate spontaneous intramural intestinal hemorrhage (SIIH) from acute mesenteric ischemia (AMI) after abdominal computed tomography (CT) survey in the emergency department (ED).

METHOD

We retrospectively included 76 patients diagnosed SIIH or AMI after abdominal CT.

RESULTS

The mean ages of 28 SIIH patients and 48 AMI patients were 75.9 ± 13.7 years and 75.8 ± 11.6 years, respectively. Patients with SIIH had significantly higher rate of Coumadin use (P < .001) and localized tenderness (P < .05). In laboratory findings, SIIH patients had prolonged prothrombin time (PT) (83.6 ± 30.0 vs. 13.4 ± 3.2, P < .001), lower blood urea nitrogen (P < .05), lower creatinine (P < .05), and lower creatine kinase (P < .05). Prolonged PT showed good discriminative value to differentiate acute abdomen patients with SIIH from AMI after abdominal CT, with an area under the receiver operating characteristic curve of 0.980 (95% confidence interval, 0.918-0.998; P < .0001). Prolonged PT cut-off value of ≧22.5 seconds had a sensitivity of 92.9% and a specificity of 100%. Logistic regression analysis identified prolonged PT as an independent predictor of SIIH (odds ratio, OR, 22.2; P = .007).

CONCLUSION

Abdominal pain patients with either SIIH or AMI are rare in the ED, but abdominal CT sometimes cannot help to differentiate them due to similar CT findings. Prolonged PT might help emergency physicians and surgeons differentiate SIIH from AMI in such cases.

Ischemic colitis: the ABCs of diagnosis and surgical management

Ischemic colitis (IC) is a rare condition. As ischemia is often transient and clinical symptoms are reversible, its exact incidence is unknown. In current clinical practice, two types of IC are described according to the severity: severe IC, with transmural colonic ischemia and/or multi-organ failure (MOF), and mild IC, without MOF and spontaneous favourable evolution in most cases. Two clinical contexts are encountered: spontaneous IC (SIC) and postoperative IC (POIC), mainly after aortic surgery. As there is no specific clinico-biologic symptom of IC, emergent CT-scan and rectosigmoidoscopy are required for diagnosis confirmation, surgical decision and prognosis analysis. IC surgical treatment is not consensual but can be standardized according to organ function and the degree of ischemia: surgical treatment in case of colonic necrosis with deep ischemia and/or MOF; observation for superficial ischemia without organ dysfunction; systematic medical care. Surgery is required in 20% of cases, and consists in extended colectomy without continuity restoration and prophylactic cholecystectomy. Continuity restoration is feasible in one third of survivors, who are exposed to a high risk of severe cardiovascular events.

Real-time in vivo imaging of early mucosal changes during ischemia-reperfusion in human jejunum

Background and study aims

Small intestinal ischemia-reperfusion (IR) is a frequent, potentially life threatening phenomenon. There is a lack of non-invasive diagnostic modalities. For many intestinal diseases, visualizing the intestinal mucosa using endoscopy is gold standard. However, limited knowledge exists on small intestinal IR-induced, early mucosal changes. The aims of this study were to investigate endoscopic changes in human jejunum exposed to IR, and to study concordance between endoscopic appearance and histology.

Patients and methods

In 23 patients a part of jejunum, to be removed for surgical reasons, was isolated and selectively exposed to ischemia with 0, 30 or 120 minutes of reperfusion. In 3 patients, a videocapsule was inserted in the isolated segment before exposure to IR, to visualize the mucosa. Endoscopic view at several time points was related to histology (Heamatoxylin & Eosin) obtained from 20 patients.

Results

Ischemia was characterized by loss of villous structure, mucosal whitening and appearance of punctate lesions. This was related to appearance of subepithelial spaces and breaches in the epithelial lining in the histological view. Early during reperfusion, the lumen filled with IR-damaged, shed cells and VCE showed mucosal erosions, hemorrhage and intraluminal debris. At 60 minutes of reperfusion, the only remaining signs of IR were loss of villous structure and small erosions, indicating rapid mucosal healing.

Conclusions

This study shows a unique, real-time in vivo endoscopic view of early mucosal changes during IR of the human small intestine. Future studies should evaluate its usefulness in diagnosis of patients suspected of IR.

Necrotizing enterocolitis: early conventional and fluorescein laparoscopic assessment

AIM

The clinical and radiological diagnosis of necrotizing enterocolitis (NEC) can be difficult. When radiological evidence is present, severity and complications, such as perforation and full-thickness necrosis, often may not be obvious. This study aims to establish early signs of full-thickness necrosis or perforation by using standard and fluorescein laparoscopy before clinical deterioration of patients occurs.

PATIENTS AND METHODS

Thirteen patients with preoperative presumed clinical and/or radiological diagnosis of NEC underwent laparoscopy. A 4.7-mm umbilical or left upper quadrant camera port was inserted by using the open method. The abdominal cavity was inspected for bowel ischemia, fibrin, adhesion formation, and presence of free intestinal contents. If necessary, one or two 3-mm working ports were inserted for manipulation of bowel.

RESULTS

Median age of 13 patients was 17 (3-38) days. Their median weight was 1160 (910-2415) g. The first 5 infants had standard laparoscopy only, with the next 8 having fluorescein-aided assessment added to the laparoscopy. Standard laparoscopy identified perforation in 5 patients and gangrenous bowel in 2. One patient was found to have chyle ascites, and 1 patient had no abnormal findings on laparoscopy. Fluorescein identified gangrenous bowel in 3 additional patients. Laparotomy and necessary surgical intervention were performed in all 10 patients with positive laparoscopy findings. Eleven patients survived and were doing well at a median of 9 (range, 6-39) months of follow-up.

CONCLUSION

Laparoscopy helps to improve assessment of patients with a diagnosis of NEC. It allows for early identification of perforation and necrosis. Where ischemia is suspected, fluorescein laparoscopy may have an added benefit in identifying necrotic segments.

Acute thrombosis of the superior mesenteric artery in a 39-year-old woman with protein-S deficiency: a case report

Introduction

Acute thromboembolic occlusion of the superior mesenteric artery is a condition with an unfavorable prognosis. Treatment of this condition is focused on early diagnosis, surgical or intravascular restoration of blood flow to the ischemic intestine, surgical resection of the necrotic bowel and supportive intensive care. In this report, we describe a case of a 39-year-old woman who developed a small bowel infarct because of an acute thrombotic occlusion of the superior mesenteric artery, also involving the splenic artery.

Case presentation

A 39-year-old Caucasian woman presented with acute abdominal pain and signs of intestinal occlusion. The patient was given an abdominal computed tomography scan and ultrasonography in association with Doppler ultrasonography, highlighting a thrombosis of the celiac trunk, of the superior mesenteric artery, and of the splenic artery. She immediately underwent an explorative laparotomy, and revascularization was performed by thromboendarterectomy with a Fogarty catheter. In the following postoperative days, she was given a scheduled second and third look, evidencing necrotic jejunal and ileal handles. During all the surgical procedures, we performed intraoperative Doppler ultrasound of the superior mesenteric artery and celiac trunk to control the arterial flow without evidence of a new thrombosis.

Conclusion

Acute mesenteric ischemia is a rare abdominal emergency that is characterized by a high mortality rate. Generally, acute mesenteric ischemia is due to an impaired blood supply to the intestine caused by thromboembolic phenomena. These phenomena may be associated with a variety of congenital prothrombotic disorders. A prompt diagnosis is a prerequisite for successful treatment. The treatment of choice remains laparotomy and thromboendarterectomy, although some prefer an endovascular approach. A second-look laparotomy could be required to evaluate viable intestinal handles. Some authors support a laparoscopic second-look. The possibility of evaluating the arteriotomy, during a repeated laparotomy with a Doppler ultrasound, is crucial to show a new thrombosis. Although the prognosis of acute mesenteric ischemia due to an acute arterial mesenteric thrombosis remains poor, a prompt diagnosis, aggressive surgical treatment and supportive intensive care unit could improve the outcome for patients with this condition.

Acute mesenteric ischemia: diagnostic approach and surgical treatment

Mortality related to acute mesenteric arterial occlusion remains very high. Patient survival is dependent on prompt recognition and revascularization before ischemia progresses to intestinal gangrene. Biphasic computed tomography angiography has surpassed angiography as the diagnostic test of choice due to its ability to define the arterial anatomy and to evaluate secondary signs of mesenteric ischemia. Unlike chronic mesenteric ischemia, the treatment of acute arterial mesenteric ischemia, either embolic or thrombotic, remains largely surgical. This is due to the emergent need for revascularization combined with a careful evaluation of the intestines. Endovascular techniques remain useful, however, and can save precious time in the treatment of these challenging patients if integrated into a treatment pathway combined with definitive surgical treatment. A new hybrid endovascular-surgical treatment for the treatment of acute mesenteric thrombosis is described.

Ischemic colitis: surging waves of update

Ischemic colitis is the most common type of intestinal ischemia, and it represents the consequences of acute or, more commonly, chronic blockage of blood flow through arteries that supply the large intestine. Ischemic colitis is manifested through a continuum of injury and considered as an illness of the elderly. The incidence of ischemic colitis has been underestimated, because many mild cases may go unreported. Patients experience abdominal pain, usually, localized to the left side of the abdomen, along with tenderness and bloody diarrhea. Severe ischemia may lead to bowel necrosis and perforation, which results in an acute abdomen and shock, frequently, being accompanied by lactic acidosis. Although computed tomography may have indicative findings, colonoscopy is the golden standard of diagnosis. Supportive care with intravenous fluids, optimization of hemodynamic status, avoidance of vasoconstrictive drugs, bowel rest, and empiric antibiotics will produce clinical improvement within 1 to 2 days in most patients. The condition resolves completely with conservative treatment, in most cases, but late diagnosis or severe ischemia can be associated with high rates of complications and death. However, when the interruption to the blood supply is more severe or more prolonged, the affected portion of the large intestine may have to be surgically removed. The present paper aims at bringing ischemic colitis up to date, by reviewing the current medical literature and extracting the contemporary data, about its presentation, diagnosis and treatment, which is of benefit to the readership, who may encounter this potentially fatal entity.

Ischemic colitis: clinical practice in diagnosis and treatment

Ischemic colitis is the most common form of ischemic injury of the gastrointestinal tract and can present either as an occlusive or a non-occlusive form. It accounts for 1 in 1000 hospitalizations but its incidence is underestimated because it often has a mild and transient nature. The etiology of ischemic colitis is multifactorial and the clinical presentation variable. The diagnosis is based on a combination of clinical suspicion, radiographic, endoscopic and histological findings. Therapy and outcome depends on the severity of the disease. Most cases of the non-gangrenous form are transient and resolve spontaneously without complications. On the other hand, high morbidity and mortality and urgent operative intervention are the hallmarks of gangrenous ischemic colitis.

Intestinal ischemia/reperfusion injury: defining the role of the gut microbiome

Intestinal ischemia/reperfusion (I/R) injury initiates a systemic inflammatory response syndrome with a high associated mortality rate. Early diagnosis is essential for reducing surgical mortality, yet current clinical biomarkers are insufficient. Metabonomics is a novel strategy for studying intestinal I/R, which may be used as part of a systems approach for quantitatively analyzing the intestinal microbiome during gut injury. By deconvolving the mammalian–microbial symbiotic relationship systems biology thus has the potential for personalized risk stratification in patients exposed to intestinal I/R. This review describes the mechanism of intestinal I/R and explores the essential role of the intestinal microbiota in the initiation of systemic inflammatory response syndrome. Furthermore, it analyzes current and future approaches for elucidating the mechanism of this condition.

Acute Mesenteric Ischemia: The Importance of Early Surgical Consultation

Acute mesenteric ischemia continues to be associated with high mortality. We hypothesized that delays in surgical consultation and operation are independently associated with increased mortality and sought to identify modifiable characteristics associated with delayed management. We conducted a retrospective cohort study of 72 patients diagnosed with acute mesenteric ischemia. Twenty-six (36%) patients died, of which 14 (54%) had care withdrawn. Delay in operation (>6 hours after surgical consultation) was associated with increased mortality (adjusted OR 3.7; 90% CI, 1.1-12). For patients for whom care was not withdrawn, delay in surgical consultation (>24 hours after disease onset) was associated with increased mortality (adjusted OR, 9.4; 90% CI, 1.3-65), as was delay in operation (adjusted OR, 4.9; 90% CI, 1.1-22). For those managed medically, early surgical consultation was associated with improved mortality (Odds Ratio [OR], 0; 90% Confidence Interval [CI], 0-0.34). Patients with delayed surgical consultation were more likely to have abdominal distension, elevated lactate concentration, acute renal failure, vasopressor administration, and a lack of abdominal pain. The acquisition of CT imaging trended toward an association with delayed surgical consultation ( P = 0.06). We conclude that early surgical consultation is associated with improved outcome even for patients managed without operative intervention, and that CT imaging may delay appropriate care.

Spectrum of non-inflammatory bowel disease and non-infectious colitis

A variety of inflammatory diseases of the colon, which can be differentiated from inflammatory bowel disease (IBD) and infectious colitis by their clinical, endoscopic and histological characteristics, are reported as non-IBD and non-infectious colitis. These diseases include microscopic colitis, ischemic colitis, segmental colitis associated with diverticula, radiation colitis, diversion colitis, eosinophilic colitis and Behcet's colitis. The etiopathogenesis of most of these diseases remains obscure and the epidemiological data are rather limited. These conditions are often troublesome for the patient and are associated with diagnostic difficulties for the physician. In many cases the treatment is empirical and there is a need for future research using randomized controlled trials.

Ischemic colitis: Clinical practice in diagnosis and treatment

Ischemic colitis is the most common form of ischemic injury of the gastrointestinal tract and can present either as an occlusive or a non-occlusive form. It accounts for 1 in 1000 hospitalizations but its incidence is underestimated because it often has a mild and transient nature. The etiology of ischemic colitis is multifactorial and the clinical presentation variable. The diagnosis is based on a combination of clinical suspicion, radiographic, endoscopic and histological findings. Therapy and outcome depends on the severity of the disease. Most cases of the non-gangrenous form are transient and resolve spontaneously without complications. On the other hand, high morbidity and mortality and urgent operative intervention are the hallmarks of gangrenous ischemic colitis.

Acute mesenteric ischemia after cardio-pulmonary bypass surgery

Acute mesenteric ischemia (AMI) is a highly-lethal surgical emergency. Several pathophysiologic events (arterial obstruction, venous thrombosis and diffuse vasospasm) lead to a sudden decrease in mesenteric blood flow. Ischemia/reperfusion syndrome of the intestine is responsible for systemic abnormalities, leading to multi-organ failure and death. Early diagnosis is difficult because the clinical presentation is subtle, and the biological and radiological diagnostic tools lack sensitivity and specificity. Therapeutic options vary from conservative resuscitation, medical treatment, endovascular techniques and surgical resection and revascularization. A high index of suspicion is required for diagnosis, and prompt treatment is the only hope of reducing the mortality rate. Studies are in progress to provide more accurate diagnostic tools for early diagnosis. AMI can complicate the post-operative course of patients following cardio-pulmonary bypass (CPB). Several factors contribute to the systemic hypo-perfusion state, which is the most frequent pathophysiologic event. In this particular setting, the clinical presentation of AMI can be misleading, while the laboratory and radiological diagnostic tests often produce inconclusive results. The management strategies are controversial, but early treatment is critical for saving lives. Based on the experience of our team, we consider prompt exploratory laparotomy, irrespective of the results of the diagnostic tests, is the only way to provide objective assessment and adequate treatment, leading to dramatic reduction in the mortality rate.

Diagnostic value of plasminogen activity level in acute mesenteric ischemia

AIM: To investigate the changes in plasminogen activity level during mesenteric ischemia.

METHODS: We performed laparotomy in 90 female Wistar-Albino rats (average weight 230 g). In sham groups (SL) (GroupsIand II) the superior mesenteric artery (SMA) and vein (SMV) were explored, but not tied. In SMA groups (Groups III and IV) the SMA was ligated, and in SMV groups (Groups V and VI) the SMV was ligated. On re-laparotomy 2 mL of blood was drawn at 1 h in groupsI, III and V, and at 3 h in groups II, IV and VI. Plasminogen levels were assessed and comparisons were made between groups and within each group.

RESULTS: The mean plasminogen activity in the SL group was significantly higher than SMA (25.1 ± 10.8 vs 11.8 ± 4.6, P < 0.001) or SMV (25.1 ± 10.8 vs 13.7 ± 4.4, P < 0.001) groups both at 1 h and at 3 h (29.8 ± 8.9 vs 15.1 ± 5.7, P < 0.0001; 29.8 ± 8.9 vs 14.2 ± 2.9, P < 0.0001). There were no significant differences between the values of SMA and SMV groups at 1 h (P = 0.28) and at 3 h (P = 0.71). In each group, plasminogen activity levels did not change significantly between the two measurements performed at 1 h and 3 h.

CONCLUSION: We conclude that blood plasminogen activities decrease during early phases of both arterial and venous mesenteric ischemia which may be a useful marker for early diagnosis.

Laparoscopic Diagnostics of Acute Bowel Ischemia Using Ultraviolet Light and Fluorescein Dye: An Experimental Study

PURPOSE

The aim of the study was to show the diagnostic potential of laparoscopy using fluorescein dye and ultraviolet light in acute bowel ischemia.

MATERIALS AND METHODS

The study involved 12 domestic pigs. Under general anesthesia, the peripheral branch of the superior mesenteric artery was embolized using polyvinyl-alcohol microparticles. Two hours after the embolization, optical filters were placed into the laparoscopic set to produce ultraviolet light. Fluorescein dye was given intravenously, and the bowel was inspected. Clips were placed on the border of the ischemia that was visualized with fluorescein. Resection of the ischemic part of the bowel and anastomosis of the viable parts were carried out using laparoscopic linear cutting staplers. After 24 hours, a laparoscopic second-look procedure was carried out to verify the viability of the anastomosis.

RESULTS

The method was in all cases able to recognize intestinal ischemia and reliably differentiate ischemic bowel segments from viable bowel. Microscopic analysis of the ischemic specimens showed beginning ischemic changes of the bowel tissues.

CONCLUSIONS

The method should be considered a valuable diagnostic procedure both for diagnostics of early stage of acute bowel ischemia and for second-look procedures.

Biomagnetic investigation of injury currents in rabbit intestinal smooth muscle during mesenteric ischemia and reperfusion

A noninvasive, sensitive, and specific method of detecting mesenteric ischemia would be of great use in reducing the morbidity and mortality with which it is associated. Acute lesions in polarized electrically coupled tissues lead to injury currents driven by the transmembrane resting potential gradient. These injury currents are an effective indicator of pathophysiology. The presence of near-DC injury currents in rabbit intestinal smooth muscle has already been demonstrated using a Superconducting quantum interference device (SQUID), and the aim of this study was to evaluate the effect of arterial reperfusion upon these currents. We exteriorized the small bowel of 14 New Zealand white rabbits and placed a remotely operated vascular occluder around the distal most artery supplying a 3-in segment of the jejunum. Experiments were conducted in three groups, i.e., control (n=3), ischemia (n=6), and reperfusion following ischemia (n=5). The subject's position was modulated in and out of the biological field detection range of a SQUID magnetometer using a lift constructed of nonmagnetic material. The changes in magnetic field amplitude were 9.3 and 31.01% for the control and ischemia groups, respectively. The reperfusion group first exhibited a decrease of 17.35% from the pre-ischemic to the ischemic period, followed by an increase of 13.88% of the ischemic value after reestablishing perfusion. In conclusion, injury currents in GI smooth muscle that appear during ischemia are reduced to near-pre-ischemic levels during reperfusion.

Validation of IC-VIEW fluorescence videography in a rabbit model of mesenteric ischaemia and reperfusion

BACKGROUND/AIMS

Mortality in mesenteric ischaemia can be reduced by an optimised extent of resection. Up to now, no technique supplementing a surgeon's experience has achieved clinical acceptance. Besides a qualitative interpretation, the new technique of computer-assisted laser-fluorescence videography affords quantification of staining intensities. The aim of this study was to investigate the scientific value of this technique in mesenteric ischaemia in a rabbit model of controlled mesenteric ischaemia and reperfusion.

METHODS

We used an established rabbit model of mesenteric ischaemia (group I, n=6) and reperfusion (group II, n=6). In each animal, three loops (each of 10 cm) of the small intestine were clamped (group I, 40 min; group II, 60 and 20 min reperfusion). For further evaluation, all loops were divided into five segments of 2 x 2 cm (total number of investigated areas, n=180). Measurement of vascular patency was performed by laser-fluorescence videography (pixel intensity per second). As standard, we used radioactive microspheres (impulse per minute per gram). In addition, the extent of ischaemic tissue damage was identified by histological examination. Statistical data were analysed by using regression analysis to define the regression coefficient r.

RESULTS/FINDINGS

Laser-fluorescence videography and the microsphere technique demonstrated a close and linear correlation: ischaemic segments, r=0.90+/-0.07; reperfusion segments, r=0.85+/-0.02; overall, r=0.92+/-0.07. There was no reproducible correlation to cellular damage in histology.

INTERPRETATION/CONCLUSION

Computer-assisted laser-fluorescence videography is a feasible, reliable, and valid experimental method for the detection of mesenteric blood supply and intestinal microcirculation. Clinical application is conceivable in mesenteric ischaemia and infarction as well as the operative transposition of intestine. As limiting values to identify the irreversible necrosis are not yet defined, further studies have to analyse the clinical impact more precisely.

Analysis of the correlation of plasma NO and ET-1 levels in rats with acute mesenteric ischemia

Mesenteric ischemia is a devastating disease process that frequently challenges clinicians. To enhance the early diagnosis of gut ischemia and judgment of its severity, it may be helpful to detect the unusual existence or increase in biomarkers in the body fluid. The aim of the present study was to evaluate the correlation of plasma nitric oxide (NO) and endothelin-1 (ET-1) levels to mesenteric ischemia using an animal model. Acute mesenteric ischemia (AMI) was produced experimentally by occlusion of the mesenteric vessels in the terminal ileum by the tenting of a thread. The determination of plasma NO and ET-1 levels were obtained before operation (T0, baseline value), and at 10 (T10), 20 (T20), 30 (T30), and 60 (T60) min after the creation of AMI. Sham-operated rats served as controls. After 30 min of experiments, the plasma NO and ET-1 levels were significantly higher in the AMI group than in the control group (both p < .01). Both the plasma NO and ET-1 levels in AMI group increased significantly after 30 min of ischemia (both p < .001 vs. respective baseline value), and they were 60% and 84% above the baseline value, respectively. In addition, ischemic intestinal injury was confirmed by the significantly elevated histological scores in the AMI group after 60 min of ischemia (p < .001). Our preliminary results suggest the possibility of important insights regarding NO and ET-1 changes into the mechanism of pathogenesis in AMI in rats. The increases in plasma NO and ET-1 levels may potentially be noninvasive biomarkers for the early detection of this disease.

Thrombolytic therapy for acute superior mesenteric artery occlusion

The aim of this review is to evaluate thrombolytic therapy for acute superior mesenteric artery occlusion as an alternative or adjunctive treatment modality to surgical therapy and to provide current knowledge for timely and informed decisions regarding treatment of acute mesenteric ischemia. A systematic analysis of the available literature from 1966 to 2003 regarding thrombolytic therapy for superior mesenteric artery thromboembolism was performed. A total of 20 case reports and seven small series covered 48 patients with acute superior mesenteric artery thromboembolism. In the herein reviewed series, thrombolytic therapy of acute superior mesenteric artery thromboembolism resulted in angiographic resolution of the thromboembolism in 43 patients, in clinical success without requiring additional surgical intervention in 30 patients, and in survival in 43 patients, with similar complication rates as in thrombolytic treatment of peripheral vascular occlusions. Remission of abdominal pain during the first few hours of treatment formed the most important indicator of therapeutic success. Insufficient evidence from reviewed literature is available to determine the relative effectiveness and safety of thrombolytic treatment for acute superior mesenteric artery thromboembolism; however, initial results appear to be promising. Thrombolytic therapy can be effective relatively quickly, may obviate surgery, and has the potential to resolve the clot completely. In some cases it can be used as an alternative or neo-adjunctive treatment modality to surgery. A treatment guideline for thrombolysis of acute superior mesenteric artery thromboembolism should be developed.

Clinical factors and outcomes in patients with acute mesenteric ischemia in the emergency department

BACKGROUND

The purpose of this study was to determine the initial clinical characteristics of acute mesenteric ischemia and identify variables associated with adverse outcomes in the emergency department (ED).

METHODS

The charts of 124 consecutive patients with surgically and pathologically identified acute mesenteric ischemia from September 1990 to September 2000 were reviewed retrospectively to obtain data about demographics, initial clinical presentations, predisposing diseases, previous medications, laboratory tests, and common findings on computed tomography scans with contrast. Only patients admitted through the ED and treated on medical or surgical wards were enrolled.

RESULTS

Mean patient age was 71.1 years (range, 25-100 years). The overall mortality rate was 50%. There were no significant differences in gender, underlying disease, previous medication, initial signs and symptoms, and causes of mesenteric infarction, between survivors and non-survivors. Univariate analysis demonstrated that older age, bandemia, hepatic and renal impairment, hyperamylasemia, metabolic acidosis, hypoxia, intramural pneumatosis, and septic syndrome, were more frequent in patients who died than in those who survived (p < 0.05). Logistic regression identified the following variables as independent predictors of death: old age (odds ratio, OR, 1.077; 95% confidence interval, Cl, 1.013, 1.146; p = 0.02); bandemia (OR, 3.894; 95% Cl, 1.160, 13.074; p = 0.03); elevated serum aspartate aminotransferase (AST; OR, 4.532; 95% Cl, 1.274, 16.122; p = 0.02); increased blood urea nitrogen (BUN; OR, 7.219; 95% Cl, 1.166, 44.696; p = 0.03); and metabolic acidosis (OR, 6.604; 95% Cl, 1.804, 24.171; p < 0.01).

CONCLUSION

A high index of suspicion and aggressive diagnostic imaging can facilitate early diagnosis and improve outcomes for patients with acute mesenteric ischemia. Risk stratification showed that elderly patients with metabolic acidosis, bandemia, or elevated AST and BUN had a poor prognosis. Greater therapeutic intervention is advocated to reduce mortality in high-risk patients with acute mesenteric ischemia.

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.

MR imaging of apparent small-bowel perfusion for diagnosing mesenteric ischemia: feasibility study

The purpose of this study, which was approved by the institutional review board, was to assess the differentiation of individuals with from those without mesenteric ischemia. All subjects provided written informed consent. Six healthy volunteers and six patients with documented chronic mesenteric ischemia underwent magnetic resonance (MR) imaging with and without oral caloric stimulation. After intravenous administration of paramagnetic contrast material, signal intensity values of the small-bowel wall were measured up to 130 seconds after contrast material injection. Volunteers and patients, respectively, had maximum enhancement of the bowel wall between 70 and 85 seconds after contrast material administration that amounted to 269% and 267% without and 425% and 333% with caloric stimulation. MR imaging assessment of small-bowel perfusion is possible and seems feasible for differentiating individuals with from those without mesenteric ischemia.

Infarcted intestine: a diagnostic void

The diagnostic approaches to infarction of the small intestine are reviewed in the present paper. The inadequacy of current methods, especially biochemical methods, are highlighted. Additionally, the benefits of a sensitive and specific test of intestinal infarction are discussed.

Protective effect of glycine in mesenteric ischemia and reperfusion injury in a rat model

PURPOSE

Glycine has a protective effect in renal and skeletal muscle ischemia. The purpose of this study was to evaluate the effect of glycine in mesenteric ischemia and reperfusion injury in a rat model.

METHODS

Twenty-four anesthetized male Sprague-Dawley rats were subjected to 1 hour of mesenteric ischemia followed by 2 hours of reperfusion. Control animals received normal saline solution intravenously at 0.01 mL/g of body weight/h during ischemia and reperfusion. Treated animals received glycine at 0.5, 0.75, or 1.0 mg/g of body weight, dissolved in saline solution and infused at 0.01 mL/g/h for 2 hours. Animals were killed at the end of the experiment, and proximal, middle, and distal segments of the small bowel were isolated. Sections of the segments stained with hematoxylin-eosin were subjected to histologic examination (as per modified Chiu grading system) and morphometric analysis consisting of measurement of bowel wall, muscularis and mucosal thickness, epithelial coverage, and villar circumference. Isometric tension responses to electrical stimulation (10, 30, 50, 100 Hz), high doses of potassium (120 mmol/L), and carbachol (0.1, 0.5, 1.0, 5.0 micromol/L) were recorded in a multimuscle chamber. Statistical analysis was performed with unpaired t test and one-way analysis of variance.

RESULTS

The middle and distal segments of the small bowel in glycine-treated animals showed better histologic grade compared with saline solution-treated control rats (P <.05). At morphometric analysis, total thickness, mucosal thickness, and villar circumference ratio were well preserved in the middle and distal segments of the small bowel in the glycine-treated group (P <.05). No significant differences were observed in the proximal bowel segments between glycine-treated and control animals, because the proximal segment was not subjected to much ischemia. No differences were noted in percentage of epithelial coverage. Isometric tension responses evoked by electrical stimulation were greater (P <.05) in the middle and distal segments treated with glycine as compared with control segments. Carbachol-evoked contractions were stronger (P <.05) in the small bowel segments of animals treated with glycine. The responses evoked by 120 mmol/L of potassium were stronger in the distal segments of the small bowel in the glycine-treated group (P <.05). This cytoprotective effect of glycine was not dose-dependent.

CONCLUSIONS

Glycine improved mucosal viability in the ischemia and reperfusion injury rat model. Mucosal thickness and villous circumference ratio were reliable objective parameters for evaluation of intestinal ischemia injury. Glycine improved the contractile responses of the bowel segments also, probably by altering the physiologic mechanisms underlying force generation. Further studies are required to elucidate the mechanism of the cytoprotective action of glycine.

Intestinal ischemia

Ischemic injury to the gastrointestinal tract can threaten bowel viability with potential catastrophic consequences, including intestinal necrosis and gangrene. The presenting symptoms and signs are relatively nonspecific and diagnosis requires a high index of clinical suspicion. AMI often results from an embolus or thrombus within the SMA, although a low-flow state through an area of profound atherosclerosis may also induce severe ischemia. Because most laboratory and radiologic studies are nonspecific in early ischemia an aggressive approach to diagnosis with imaging of the splanchnic vasculature by mesenteric angiography is advocated. Various therapeutic approaches, including the infusion of vasodilators and thrombolytics, may then be used. Proper diagnosis and management of patients with AMI requires vigilance and a readiness to pursue an aggressive course of action.

The effects of intestinal ischemia on the levels of serum immunoglobulin A in rats

Many biochemical markers have been investigated in intestinal ischemia. However, the effects of intestinal ischemia on the level of serum immunoglobulin A (IgA) has apparently not been investigated in the literature, although the gastrointestinal system is one of the main sources of serum IgA. The aim of our study was to evaluate the changes of serum IgA levels during intestinal ischemia of varying duration in rats. Group 1 ( n=5) was created for control purposes, including the detection of the baseline values and the effects of the anesthetic agents. Group 2 ( n=20) rats underwent sham laparotomy. Group 3 ( n=20) had 50% of small intestine ischemia by the strangulated obstruction model. Serum samples were obtained by cardiac puncture 1 h after anesthetic agents were given in group 1. On the other hand, serum and intestine samples were obtained at 1 (T1, n=5), 2 (T2, n=5), 4 (T4, n=5) and 6 (T6, n=5) h after the operation in groups 2 and 3. The levels of serum IgA, lactic dehydrogenase (LDH) and alkaline phosphatase (ALP) were determined. Pathologic specimens were graded in a masked manner. IgA levels were abruptly decreased to 8.49+/-1.58 mg/dl in rats with intestinal ischemia at 1 h after the operation. This decrease in serum IgA at T1 in group 3 was statistically significant compared with the control and sham-operated groups (18.80+/-1.15 mg/dl, 22.07+/-1.54 mg/dl, respectively; P<0.01). On the other hand, IgA levels were significantly elevated at T2 in the sham-operated group compared with control and intestinal ischemia groups (26.99+/-2.96 mg/dl, 18.80+/-1.15 mg/dl, 14.35+/-2.62 mg/dl, respectively; P<0.05). The serum IgA levels decreased to above baseline values at T6 in group 2 (19.60+/-2.78 mg/dl), while they increased to below baseline values in group 3 (17.60+/-1.28 mg/dl). In group 3, IgA levels were elevated to baseline values, while a significant ischemia occurred at 4 and 6 h after operation. These results suggested that serum IgA is affected earlier by intestinal ischemia and intestinal manipulation. The increase in serum IgA levels may be related to stimulation of the local immune responses in the intestine. On the other hand, abruptly decreasing serum IgA levels in this experimental study may be related to inadequate transport of the synthesized IgA to the systemic circulation, because serum IgA levels were returned to baseline values while a significant ischemia occurred at T4 and T6. According to these results, we conclude that serum and peritoneal fluid IgA levels may be changed by intestinal ischemia and may be used to make an early diagnosis of intestinal ischemia in humans.

Laparoscopic evaluation of intestinal ischemia using fluorescein and ultraviolet light in a porcine model

BACKGROUND

The laparoscopic use of fluorescein and ultraviolet light may be a useful diagnostic tool that potentially could reduce the time until diagnosis and the subsequent mortality of mesenteric ischemia.

METHODS

Eight pigs were subjected to a pneumoperitoneum pressure of 7 mmHg, and another eight pigs were exposed to a pressure of 14 mmHg. A segment of small bowel was devascularized. Two filters were used to create ultraviolet light. Pigs from each pressure group were given various intravenous fluorescein doses. The ischemic segment of the small intestine and other structures were inspected laparoscopically with the filters attached. A videotape was evaluated by resident and attending surgeons.

RESULTS

Ischemic bowel was seen as a darkened silhouette against the viable fluorescent tissue. Overall, the results show that the use of ultraviolet light and fluorescence in the laparoscopic model is adequate for allowing the identification of ischemic bowel.

CONCLUSIONS

The laparoscopic use of ultraviolet light combined with intravenous fluorescein dye is an effective diagnostic tool for evaluating mesenteric ischemia in pigs.

Outcome of splanchnic blood flow determination in patients with suspected chronic intestinal ischaemia. A retrospective survey

BACKGROUND

Different diagnostic examinations have been applied in the management of patients with suspected intestinal ischaemia. In some centres, invasive determination of a meal-induced increase in splanchnic blood flow is used in the diagnostic process and in the selection of patients for surgery. However, no studies have evaluated the impact of splanchnic blood flow determination on therapy in such patients.

OBJECTIVE

The aim of the present study was therefore to analyse the outcome of splanchnic blood flow determination in patients with suspected chronic intestinal ischaemia.

METHODS

Seventy-three consecutive patients with suspected intestinal ischaemia were included during a 5-year period. Splanchnic blood flow was determined at baseline and after a standardized meal. The patients were classified into three groups according to the level of meal-induced increase in splanchnic blood flow: A, normal response (splanchnic blood flow > or = 200 ml/min); B, possible abnormal response (splanchnic blood flow 51-199 ml/min); and C, definitive abnormal response (splanchnic blood flow < or = 50 ml/min). Where surgery took place, the type of operation was noted.

RESULTS

Forty patients had a normal meal-induced response, 23 patients had a possible abnormal response and 10 patients had a definitive abnormal response, which gave evidence of chronic intestinal ischaemia. In the total patient population, the increase in splanchnic blood flow was significantly correlated to an increase in hepatic oxygen uptake (r = 0.38, P < 0.002) and to body weight (r = 0.36, P < 0.01). A total of seven patients (10%) underwent successful revascularization.

CONCLUSIONS

Ten of the patients with suspected chronic intestinal ischaemia had abnormal meal-induced splanchnic blood flow and 30% of these patients underwent angioplasty. Future studies are needed to validate the determination of splanchnic blood flow in relation to splanchnic angiography and other imaging modalities in patients with chronic intestinal ischaemia.

Diagnosis and treatment of nonocclusive mesenteric ischemia after open heart surgery

BACKGROUND

Acute nonocclusive mesenteric ischemia (NOMI) is a rare but often fatal event after cardiac surgery.

METHODS

Twenty patients with ongoing ileus after cardiac surgery despite maximal laxative treatment underwent selective mesenteric angiography. In cases of pathological radiographic findings, papaverine was continuously administered via an intraarterial perfusion catheter.

RESULTS

Severe NOMI was confirmed in seven patients (mean lactate: 6.9 +/- 8.3 mg/dL), mild to moderate findings in another seven (mean lactate: 1.4 +/- 1.1 mg/dL). One patient had thromboembolic occlusion of the superior mesenteric artery; five patients demonstrated normal imaging findings. In nine of fourteen patients (64%) treated with papaverine, symptoms improved within hours (defecation occurred after 4-29 hours, mean 13 +/- 8.1 hours). No side effects or complications occurred in connection with the papaverine treatment. The clinical condition of five patients deteriorated. Four patients underwent laparotomy with creation of an ileostomy or colostomy, two of whom presented with severe intestinal ischemia and later died. One patient died prior to laparotomy.

CONCLUSIONS

Selective mesenteric angiography with continuous papaverine administration is a simple, fast, and effective diagnostic and therapeutic tool to reduce the need for laparotomy for symptoms of ileus after open-heart surgery.

Ischemic bowel disease in the elderly

The ischemic bowel diseases are a heterogeneous group of disorders usually seen in elderly individuals. They represent ischemic damage to different portions [figure: see text] of the bowel and produce a variety of clinical syndromes and outcomes. Colonic ischemia is the commonest of these disorders and has a favorable prognosis in most cases. In contrast, acute mesenteric ischemia, most commonly caused by a superior mesenteric artery embolus, is a disease with a poor prognosis. Acute mesenteric ischemia secondary to nonocclusive mesenteric ischemia usually is a [figure: see text] catastrophic complication of other severe medical illnesses, most notably atherosclerosis. Proper diagnosis and management of patients with ischemic bowel disease requires vigilance on the part of the physician and a willingness to embark on an aggressive plan of diagnosis and management in the appropriate setting.

Chronic splanchnic ischaemia

Chronic splanchnic ischaemia is a relatively unusual clinical entity consisting of pain and/or weight loss and caused by chronic splanchnic disease (i.e. stenosis and/or occlusion of the coeliac and superior mesenteric artery). The occlusive disease is usually caused by atherosclerosis and is in itself not rare in older individuals. Extensive collateral circulation can develop between the three splanchnic arteries and may compensate for the decreased splanchnic perfusion over time. The pathophysiology of chronic splanchnic ischaemia has still not been completely elucidated.A reliable diagnosis of chronic splanchnic ischaemia, based on a proven causal relationship between the occlusive disease and the symptoms, can be very difficult. Traditionally, tests for evaluating the haemodynamic consequences of the vascular stenoses were not available. Important improvements in establishing a more reliable diagnosis have been achieved with duplex ultrasound and magnetic resonance evaluation of the splanchnic circulation. Tonometry is another promising functional test that may prove useful not only for gaining greater insight into the pathophysiology of chronic splanchnic ischaemia but also for the clinical evaluation of this syndrome. The natural history of chronic splanchnic disease suggests that progressive disease may result in acute mesenteric ischaemia. Surgical reconstruction of the coeliac and/or the superior mesenteric artery is the therapeutic standard with excellent short and long-term results. Satisfactory early results using angioplasty with or without stent suggest that this type of intervention may relieve symptoms in selected patients with a higher surgical risk.

Acute intestinal ischaemia

The subsets of acute mesenteric ischaemia include mesenteric arterial occlusion (by embolus or thrombosis), mesenteric venous thrombosis and non-occlusive mesenteric ischaemia. Despite advances in pathophysiology, laboratory diagnosis and imaging techniques, acute mesenteric ischaemia is still associated with mortality rates of more than 60% and continues to be a challenging diagnostic problem. The key to a better outcome (and the main problem in clinical practice) is early diagnosis. Clinical presentation may be unspecific, but is often characterized by an initial discrepancy between severe subjective pain and relatively unspectacular findings on physical examination. Up to now, there are no simple and non-invasive diagnostic tests of sufficient sensitivity and specificity; thus, angiography remains the cornerstone of diagnosis and should be performed early in all patients in which mesenteric ischaemia is a realistic differential diagnosis. Treatment for obstructive mesenteric arterial syndromes and most patients with mesenteric venous thrombosis is surgical, whereas non-occlusive mesenteric ischaemia may be managed by pharmacological vasodilation.

Ischaemia/reperfusion contributes to colonic injury following experimental aortic surgery

OBJECTIVES

ischaemia of the colon is an important complication of abdominal aortic aneurysm (AAA) repair. The aim of this animal study was to investigate the effect of sequential ischaemia and reperfusion on sigmoid mucosal pO2 and its association with local ET-1 release.

MATERIAL AND METHODS

twelve pigs underwent colonic ischaemia followed by complete reperfusion. Six other animals were sham controls. A Clark-type microcatheter was used for continuous mucosal pO2 measurements. Serial systemic and inferior mesenteric vein blood samples were obtained for determination of ET-1 concentration. Neutrophil extravasation was assessed by tissue myeloperoxidase (MPO) activity.

RESULTS

arterial occlusion was associated with a gradual decrease of mucosal pO2 and local release of ET-1. After restoration of blood flow, mucosal pO2 returned to near baseline values, whereas ET-1 reached its maximum concentration during the reperfusion period. MPO activity was significantly increased.

CONCLUSIONS

colonic ischaemia and reperfusion causes neutrophil extravasation and local ET-1.

AGA technical review on intestinal ischemia. American Gastrointestinal Association

This literature review and the recommendations therein were prepared for the American Gastroenterological Association Clinical Practice and Practice Economics Committee. The paper was approved by the committee on September 25, 1999, and by the AGA Governing Board on November 25, 1999.