Nonocclusive acute mesenteric ischemia

The authors present one case of acute mesenteric ischemia appeared to the patient 70 years old, with HTA and coronary heart disease with heart arrhythmia treated with angiotensin-converting-enzyme inhibitor, anti arrhythmia agents and antithrombin therapy (trombostop). Acute mesenteric ischemia is not an isolated clinical entity, but a complex of diseases, including acute mesenteric arterial embolus and thrombus, mesenteric venous thrombus and nonocclusive mesenteric ischemia. These diseases have common clinical features caused by impaired blood perfusion of the intestine, bacterial translocation and systemic inflammatory response syndrome. Reperfusion injury is another important feature of nonocclusive mesenteric ischemia. We discuss about the nonocclusive mesenteric ischemia is the most lethal form of acute mesenteric ischemia because of the poor understanding of its pathophysiology and its nonspecific symptoms, which often delay its diagnosis. Although acute mesenteric ischemia is still lethal and in-hospital mortality rates have remained high over the last few decades, accumulated knowledge on this condition is expected to improve its prognosis.     

Acute Mesenteric Ischemia: The Challenge of Gastroenterology

Intestinal ischemia has been classified into three major categories based on its clinical features, namely, acute mesenteric ischemia (AMI), chronic mesenteric ischemia (intestinal angina), and colonic ischemia (ischemic colitis). Acute mesenteric ischemia is not an isolated clinical entity, but a complex of diseases, including acute mesenteric arterial embolus and thrombus, mesenteric venous thrombus, and nonocclusive mesenteric ischemia (NOMI). These diseases have common clinical features caused by impaired blood perfusion to the intestine, bacterial translocation, and systemic inflammatory response syndrome. Reperfusion injury, which exacerbates the ischemic damage of the intestinal microcirculation, is another important feature of AMI. There is substantial evidence that the mortality associated with AMI varies according to its cause. Nonocclusive mesenteric ischemia is the most lethal form of AMI because of the poor understanding of its pathophysiology and its mild and nonspecific symptoms, which often delay its diagnosis. Mesenteric venous thrombosis is much less lethal than acute thromboembolism of the superior mesenteric artery and NOMI. We present an overview of the current understanding of AMI based on reported evidence. Although AMI is still lethal and in-hospital mortality rates have remained high over the last few decades, accumulated knowledge on this condition is expected to improve its prognosis.     

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??Acute mesenteric ischemia: the diagnostic challenge and treatment options XIN Shi-jie, WANG Lei. Division of Vascular and Thyroid Surgery, Department of General Surgery, the First Hospital of China Medical University, Shenyang 110001, China Corresponding author: XIN Shi-jie, E-mail: xinshijie1963@yahoo.com.cn Abstract Acute mesenteric ischemia is a life-threatening emergency with multiple etiology, including acute mesenteric arterial embolus and thrombus, mesenteric venous thrombus, nonocclusive mesenteric ischemia, and other rare conditions. Massive bowel necrosis is the endpoint of pathological process, associated with a high mortality. Despite the improvement of diagnostic technique and medical condition, there are still many patients could not accept early diagnosis and prompt effective treatment. Strong clinical suspicion based on a better understanding of risk factor, pathology, clinical characteristic and treatment options will improve the prognosis.     

Aggressive approach to acute mesenteric ischemia.

An aggressive diagnostic and therapeutic approach to acute mesenteric ischemia can dramatically lower the mortality of this lethal disease. The cornerstones of this approach are the earlier and more liberal use of angiography and the use of intra-arterial infusions of vasodilators in the treatment of both nonocclusive and occlusive mesenteric ischemia.     

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??Interventional therapy for acute mesenteric arterial ischemia LIU Bing??WANG Hai-jun. Department of Vascular Surgery??the First Affiliated Hospital of Harbin Medical University??Harbin 150001??China
Corresponding author??WANG Hai-jun??E-mail??13836162963@163.com
Abstract Acute superior mesenteric artery ischemia is a fatal emergency with multiple etiology??including acute mesenteric arterial embolus and thrombus??nonocclusive mesenteric ischemia and other rare conditions. The progression of the disease will eventually lead to massive intestinal necrosis with high mortality. Early diagnosis and operation can reduce the mortality effectively. The first choice of early treatment for acute superior mesenteric artery ischemia is interventional therapy??meanwhile essential strict indication and operation skill should be known well.     

急性肠系膜动脉缺血的介入治疗

急性肠系膜缺血是较为少见的外科急重症,包括肠系膜动脉的栓塞和血栓形成、非阻塞性肠系膜缺血以及其他少见病因。病情发展最终导致大面积肠坏死,病死率极高。早期诊断和及时的手术干预能有效降低病死率。介入治疗是急性肠系膜动脉缺血早期首选治疗手段,需严格掌握适应证和操作技巧。     

Nonocclusive intestinal ischemia in patients with acute aortic dissection

BACKGROUND: In aortic dissection, visceral complications that result from aortic branch compromise have been described extensively, whereas intestinal ischemia not associated with the false lumen anatomy has rarely been discussed. The aim of this report is to identify clinical factors that may contribute to the development of this form of acute mesenteric ischemia, to profile the patients at greatest risk, and to review diagnostic and treatment methods that emerged from our experience. METHODS: With a computerized database, we identified 371 patients who underwent treatment in our institution with a diagnosis of aortic dissection between July 15, 1985, and January 10, 2001. Mesenteric ischemia was present in 73 patients (19%). In 36 patients (9%), bowel ischemia was not associated with a false lumen anatomy or an extension of the dissection process. From a general analysis of the determinants of mesenteric ischemia in aortic dissection, we investigated, with univariate and multivariate analysis, the specific characteristics of these patients with nonocclusive ischemia. A retrospective analysis of the oxygen metabolic profile of patients who underwent operation also was performed. RESULTS: The mortality rate in patients with nonocclusive mesenteric ischemia was 86%; sepsis and multiple organ failure were the causes of death in all nonsurvivors. Surgical treatment was beneficial only in the early phases of the disease. The results of the multivariate analysis showed the multifactorial origin of nonocclusive mesenteric ischemia; cerebral ischemia, thrombosis of the false lumen, severe coagulation disorders, chronic obstructive pulmonary disease, aortic calcinosis, prolonged hypotension, chronic renal insufficiency, and low cardiac output were independent predictors of the condition. In patients who underwent operation, the significant risk factors were severe coagulation disorders, postoperative cerebral ischemia, maximal oxygen extraction rate of more than 0.40, aortic calcinosis, chronic obstructive pulmonary disease, thrombosis of the false lumen, inotropic support, and chronic renal insufficiency. An oxygen extraction rate of more than 0.4 at 6 hours after operation was found to be an index of intestinal damage sufficient to initiate an evaluation for visceral ischemia. Significant differences with occlusive ischemia also were evidenced with this study. CONCLUSION: In aortic dissection, nonocclusive mesenteric ischemia shows some unique clinical and individual predisposing factors. Most instrumental investigations are of poor diagnostic value, and prognosis is poor, especially when mesenteric gangrene had already taken place. Prevention can be exercised only with a heightening of our awareness of this condition and with timely correction of metabolic disturbances. In suspected cases, an aggressive surgical attitude may represent the only means for reducing mortality.     

Nonocclusive mesenteric ischemia after off-pump coronary artery bypass surgery: a word of caution

We present a series of five cases of off-pump coronary artery bypass surgery complicated with fatal nonocclusive mesenteric ischemia. We review a total of 489 patients aged 65 and older (mean age 74.9 +/- 3.2 years) who underwent off-pump coronary artery bypass surgery. The diagnosis of nonocclusive mesenteric ischemia was confirmed by computed tomography-angiography and/or selective angiography of the superior mesenteric artery, or intraoperatively. Three patients underwent laparotomy with bowel resection. In two cases, resection of bowel was not feasible. Of the possible predisposing factors, we found that four of the patients (two preoperative and two perioperative) had received epinephrine and two had an intra-aortic balloon counter pulsation due to acute myocardial infarction and cardiogenic shock. All patients were over 65 years of age, and all had acute anterior wall myocardial infarction and hemodynamic instability or post-myocardial infarction unstable angina. Nonocclusive mesenteric ischemia is a difficult clinical entity to recognize, has no clear-cut effective management, has a poor prognosis as a result of low cardiac output, and can be aggravated by off-pump coronary artery bypass grafting.     

Radioxenon washout for the diagnosis of low-flow mesenteric ischemia

Angiogram is accepted as one of the investigations necessary to establish the diagnosis of acute mesenteric ischemia. Unfortunately, the changes seen in the mesenteric arteriogram of patients with low-flow intestinal ischemia are not always clear and easily interpreted. In this study the washout of an intraarterial injection of radioxenon (¹³³Xe), from nonocclusive ischemic bowel, was recorded to determine if it might aid in the diagnosis of low-flow ischemia. For these investigations, a model of low-flow mesenteric ischemia was produced by infusion of noradrenalin into the dog's superior mesenteric artery (SMA). Under experimental conditions of normal and low mesenteric blood flow, the percentage disappearance at 2 min (washout), from the bowel, of a bolus intraarterial (SMA) injection of radioxenon was recorded to determine if this gave a measure of the intestinal blood flow. It was found that Xe washout and the corresponding SMA blood flow, measured with an electromagnetic flow probe, correlated well in the normal and nonocclusive ischemic bowel (r = 0.924). Measurement of the washout of an intraarterial injection of ¹³³Xe to the bowel may be a helpful adjunct to arteriogram for the clinical diagnosis of low-flow mesenteric ischemia.     

Hepatic portal vein gas detected by point of care ultrasound

IntroductionPortal venous gas is a rare finding in adults and is typically associated with underlying intestinal ischemia. Portal venous gas can be detected by a bedside point of care ultrasound (POCUS) examination in adult patients in critical care units (CCU). Findings include echogenic bubbles flowing centrifugally throughout the portal venous system.Case presentationWe present the case of a 73-year-old female with advanced ischemic cardiomyopathy and cardiorenal syndrome who was managed in the CCU. She developed vague abdominal pain and respiratory depression requiring intubation and dialysis during her course of treatment in the CCU. Her findings were consistent with portal venous gas upon POCUS, prompting computed tomography of her abdomen and surgical consultation. She was ultimately found to have nonobstructive mesenteric ischemia.Clinical discussionPVG is an ominous radiological sign and reflects intestinal ischemia in up to 72% of cases. Acute mesenteric ischemia of the small bowel could be due to occlusive or nonocclusive obstruction of the arterial blood supply or obstruction of venous outflow. Nonocclusive obstruction accounts for 5% to 15% of patients with acute mesenteric ischemia.ConclusionWith the increasing use of POCUS, critical care physicians should be aware of findings consistent with portal venous gas as a bedside tool for directing the treating physician toward an ominous diagnosis in patients with shock.     

Clinically diagnosed nonocclusive mesenteric ischemia after cardiopulmonary bypass: retrospective study

This retrospective study evaluates our experience with clinically diagnosed nonocclusive mesenteric ischemia after cardiopulmonary bypass. Twenty-three of 3,600 consecutive patients suffered from splanchnic malperfusion. Symptoms developed between day 2 and 6 postoperatively in 18 of 23 patients. Four of 23 patients had no abdominal symptoms. Laboratory evaluation revealed significantly higher serum lactate and creatine phosphokinase levels in the 18 symptomatic patients compared with those of a control group. Arteriography was performed in 20 cases and revealed nonocclusive splanchnic hypoperfusion. Risk factors for development of mesenteric ischemia include arrhythmias and low cardiac output. Patients with angiographically proven nonocclusive mesenteric ischemia were treated with intra-arterial bolus injection and subsequent intra-arterial infusion of tolazoline combined with heparin sodium. The overall mortality rate was 30% (7 of 23). Infusion therapy with tolazoline and heparin seems to be a successful treatment modality for clinically diagnosed mesenteric ischemia.     

Acute mesenterial infarcts--results of surgical therapy

Forty-five patients with mesenteric infarction documented by laparotomy or autopsy were reviewed. 35% of the patients had superior mesenteric artery occlusion by embolus, 27% by thrombosis, 11% had venous thrombosis, 9% nonocclusive mesenteric ischemia, and 18% were unclear. The mortality rate was 60% within half a year postoperatively. 22% had inoperable lesions, 46% underwent bowel resection, and 32% were managed by revascularization. In the group treated by bowel resection (n = 21) 30% died, in the group treated by revascularization 80% of the patients died.     

Acute mesenteric ischemia: an aggressive diagnostic and therapeutic approach. 1991 Roussel Lecture.

The incidence of acute mesenteric ischemia (AMI) has increased substantially over the last few decades. Death rates of 70% to 90% have been reported for traditional methods of diagnosis and therapy. Use of an aggressive radiologic, pharmacologic and surgical approach has decreased the mortality and morbidity associated with AMI. The cornerstones of management are prompt diagnosis by the earlier and more liberal use of angiography and the incorporation of intra-arterial papaverine in the treatment of both occlusive and nonocclusive AMI. Widespread adoption of this protocol in patients at risk might improve the overall results of treatment of AMI.     

Protection of the small intestine from nonocclusive mesenteric ischemic injury due to cardiogenic shock

In a pericardial tamponade model of cardiogenic shock in pigs, we had previously shown that acute reductions in cardiac output produce severe mesenteric ischemia due to disproportionate splanchnic vasoconstriction. In this study, we extended the period of cardiogenic shock in order to investigate the pathogenesis of ischemic injury to the small intestinal wall. Four hours of tamponade produced sustained changes in splanchnic hemodynamics, similar to those observed in the prior short-term experiments. The resultant mesenteric ischemia caused necrotic lesions of the small intestine which were characteristic of those seen in nonocclusive mesenteric ischemia in human subjects. Prior alpha-adrenergic blockade failed to prevent either sustained mesenteric vasospasm or ischemic injury. In contrast, prior blockade of the renin-angiotensin axis, whether by nephrectomy or angiotensin-converting enzyme inhibition, blocked the splanchnic vasoconstriction, and thereby protected the small intestine from ischemic injury. The primary hemodynamic and pathologic features of this model of nonocclusive mesenteric ischemia appear to be mediated by the renin-angiotensin axis.     

The right colon as a target organ of nonocclusive mesenteric ischemia. Case report and review of the literature

Nonocclusive mesenteric ischemia is a poorly understood process that infrequently complicates states of hemodynamic compromise. The right side of the colon appears to be particularly sensitive to this pathologic event. In a 25-year-old man, spinal shock from a gunshot injury to the thoracic spinal cord resulted in right colon necrosis from nonocclusive mesenteric ischemia. The anatomic and physiologic characteristics of the mesenteric circulation to the right colon that lead to this risk for nonocclusive mesenteric ischemia were studied.     

Hepatic portal venous gas associated with nonocclusive mesenteric ischemia in a hemodialysis patient

Hepatic portal venous gas (HPVG) has been rarely described in chronic hemodialysis patients. We report a case of HPVG in a 59-year-old female patient with hemodialysis-dependent chronic renal failure due to diabetes who presented with acute onset of abdominal pain. Abdominal CT demonstrated the presence of gas in the portal veins. However, on laparotomy, no evidence of bowel necrosis or perforation could be found. HPVG seemed to be caused by nonocclusive mesenteric ischemia (NOMI), an increasingly recognized complication in hemodialysis patients. The patient responded favorably to intravenous hyperalimentation and antibiotics.     

Impact of Etiologic Factors and APACHE II and POSSUM Scores in Management and Clinical Outcome of Acute Intestinal Ischemic Disorders after Surgical Treatment

Background Acute intestinal ischemic disorder (AIID) is an uncommon vascular disease with high mortality. According to etiology, it can be categorized into three groups: arterial occlusive mesenteric ischemia (AOMI), mesenteric venous thrombosis (MVT), and nonocclusive mesenteric ischemia (NOMI). This study analyzes the effect of classification on surgical outcome. Patients and Methods All AIID patients who underwent operative treatment at National Cheng Kung University Hospital between January 1989 and August 2003 were enrolled in this study. Preoperative information on these patients was compared to find predictors of outcome. Results Data from 77 patients (49 men and 28 women, median age 70 years) were analyzed. The etiology was AOMI in 30 patients, MVT in 19 patients, and NOMI in 28 patients. Median age was younger in MVT (54 years) than in AOMI (70 years) or NOMI (72 years). In addition, MVT usually involved the jejunum (74%, versus 31% in AOMI and 46% in NOMI), whereas both AOMI and NOMI involved ileum and colon. The patients with AOMI had shorter duration of symptoms and higher ratio of underlying hypertension than those with MVT. The overall mortality rate was 53.2% (41/77). The day 1 and day 30 mortality were 0% and 10.5% in MVT, 16.7% and 30% in AOMI, and 42.9% and 67.9% in NOMI, respectively (P < 0.05). Both the etiology and the APACHE II scores were significant risk factors for day 30 and long-term mortality. The patients with NOMI had higher POSSUM physiologic scores than patients with MVT. The P-POSSUM regression equation can accurately predict mortality. Conclusions Patients with MVT had a more favorable prognosis, whereas those with NOMI had the worst outlook. The APACHE II and POSSUM scoring systems are useful in predicting the clinical outcome. Early diagnosis and classification of AIID patients are useful for aggressive treatment to improve the clinical outcome.     

De l’ischémie mésentérique non occlusive à la colite ischémique: un spectre large

Nonocclusive mesenteric ischemia occurs preferentially in low-flow states, vasoconstriction, or hypovolemia. Its spectrum spreads from ischemic colitis to acute mesenteric ischemia. Diagnosis must be evoked by association of abdominal pain, hemodynamic failure, and morphological abnormalities in CT scan in a shocked patient or in a context or vasoactive treatments or cocaine abuse. Although CT scan allows arguments of intestinal parietal injury, positive diagnosis and treatment are based on numerised angiography. Treatment consists of correction of low-flow states, discontinuation of vasoconstrictive medications, and instauration of vasodilatatory agents during angiography. In the contrary of occlusive ischemia, surgery is not the first treatment in the management of nonocclusive mesenteric ischemia. The prognosis is very poor in case of mesenteric stroke, but favorable in case of ischemic colitis.     

Mesenteric venous thrombosis.

Mesenteric venous occlusion produces a spectrum of clinical presentations, the most common of which is the acute onset of abdominal pain with progressive signs and symptoms of bowel infarction. This acute form of mesenteric venous thrombosis, compared with other forms of acute mesenteric infarction, occurs in younger patients, typically has a more indolent and nonspecific course, involves shorter segments of bowel, and has a lower mortality rate. In contradistinction to our recommended therapy in other forms of acute mesenteric infarction, immediate anticoagulation is indicated for mesenteric venous thrombosis. Second-look operations are used, as in other forms of acute mesenteric infarction, whenever portions of bowel of questionable viability are not resected at the primary operation. Chronic mesenteric venous thrombosis may produce no symptoms or may cause gastrointestinal bleeding from portal hypertension. Newer imaging techniques have increased the ability to diagnose and define the extent of all forms of mesenteric venous thrombosis and have added to the therapeutic options available to manage them.     

Splenic artery-to-superior mesenteric artery bypass for chronic mesenteric ischemia--a case report

Chronic mesenteric ischemia (CMI) is a serious vascular condition that if left untreated may progress to acute ischemia resulting in bowel necrosis and high surgical morbidity/mortality rates. Elective intervention has been shown to prevent this progression and relieve symptoms. Current open surgical intervention involves arterial bypass using a vein or synthetic graft conduit with the inflow originating from the aorta or iliac artery. In some circumstances, the splenic artery provides an additional treatment option for revascularization of the superior mesenteric artery. In certain cases, the splenic artery has several advantages over traditional surgical options. The splenic artery is an arterial conduit much like the internal mammary artery used in coronary artery bypass grafting. These grafts are known for their long-term patency and in selected clinical circumstances are preferred over venous grafts. Because the splenic artery has a natural inflow, only a single vascular anastomosis at the outflow vessel (the SMA) is necessary. This lessens the risk of anastomotic stenosis by decreasing the number of anastomoses created and it makes the procedure shorter in duration. The fact that the inflow is provided by the splenic artery makes cross-clamping of the aorta unnecessary, thereby lessening the risk of producing cardiac ischemia and declamping hypotension. A disadvantage is the risk of splenic ischemia with the possible need for splenectomy. The majority of individuals will have adequate collateral supply to the spleen via the short gastric arteries. The risk to the patient of splenectomy versus the benefits of a less complicated arterial reconstruction with avoidance of aortic cross-clamping must be weighed on a case-by-case basis. Preventing the progression to acute mesenteric ischemia with its increased mortality by timely restoration of adequate vascular supply is an important principle in treating patients with CMI. Controversy still exists over the best treatment option for these patients, whether it be antegrade versus retrograde bypass, single-vessel versus multivessel reconstruction, or open surgical repair versus endovascular intervention. In selected patients, the use of the splenic artery can be considered as an additional option for arterial reconstruction of the SMA.