Acute mesenteric ischemia: a clinical review

Acute mesenteric ischemia is a life-threatening vascular emergency that requires early diagnosis and intervention to adequately restore mesenteric blood flow and to prevent bowel necrosis and patient death. The underlying cause is varied, and the prognosis depends on the precise pathologic findings. Despite the progress in understanding the pathogenesis of mesenteric ischemia and the development of modern treatment modalities, acute mesenteric ischemia remains a diagnostic challenge for clinicians, and the delay in diagnosis contributes to the continued high mortality rate. Early diagnosis and prompt effective treatment are essential to improve the clinical outcome.

Mesenteric venous thrombosis: still a lethal disease in the 1990s

PURPOSE

This study was designed to evaluate progress in diagnosis, management, and clinical outcome of mesenteric venous thrombosis (MVT).

METHODS

We retrospectively reviewed the clinical course of 72 patients treated for mesenteric venous thrombosis between 1972 and 1993.

RESULTS

Fifty-three patients had acute and 19 had chronic mesenteric venous thrombosis. Fifty-seven patients had secondary mesenteric venous thrombosis; previous abdominal surgical procedure and hypercoagulable states were the most prevalent associated conditions. Computed tomography was abnormal in all patients who underwent this test for acute mesenteric venous thrombosis and in 93% of those who had chronic disease. Angiography diagnosed acute mesenteric venous thrombosis in five (72%) of seven patients. Acute mesenteric venous thrombosis presented most frequently as abdominal pain (83%), anorexia (53%), and diarrhea (43%). Thirty-three (75%) had symptoms longer than 48 hours. Thirty-four (64%) patients with acute mesenteric venous thrombosis underwent a surgical procedure. Bowel resection was necessary in 31 patients. One patient had unsuccessful mesenteric venous thrombectomy. Seven patients with acute mesenteric venous thrombosis underwent anticoagulation without a surgical procedure, and 12 were observed. All patients with chronic mesenteric venous thrombosis were observed; nine of the 19 underwent anticoagulation. The median delay in diagnosis for patients with acute mesenteric venous thrombosis was 48 hours and did not decrease during the last decade. Mesenteric venous thrombosis recurred in 19 (36%) patients. The 30-day mortality was 27%. Long-term survival of patients with acute mesenteric venous thrombosis was significantly worse than that of those with chronic disease (36% vs 83% survival at 3 years). The patients with acute mesenteric venous thrombosis who underwent anticoagulation with and without surgical procedure had improved survival when compared with the observed group.

CONCLUSION

Acute mesenteric venous thrombosis remains a lethal disease. Mortality has not improved in the last 22 years. Computed tomography is the most sensitive diagnostic test. Anticoagulation and surgical procedure enhanced survival in the acute subgroup. The underlying disease determined survival in chronic disease.

CT and MR imaging findings of bowel ischemia from various primary causes

Ischemic bowel disease represents a broad spectrum of diseases with various clinical and radiologic manifestations, which range from localized transient ischemia to catastrophic necrosis of the gastrointestinal tract. The primary causes of insufficient blood flow to the intestine are diverse and include thromboembolism, nonocclusive causes, bowel obstruction, neoplasms, vasculitis, abdominal inflammatory conditions, trauma, chemotherapy, radiation, and corrosive injury. Computed tomography (CT) or magnetic resonance (MR) imaging can demonstrate the ischemic bowel segment and may be helpful in determining the primary cause. The CT and MR imaging findings include bowel wall thickening with or without the target sign, intramural pneumatosis, mesenteric or portal venous gas, and mesenteric arterial or venous thromboembolism. Other CT findings include engorgement of mesenteric veins and mesenteric edema, lack of bowel wall enhancement, increased enhancement of the thickened bowel wall, bowel obstruction, and infarction of other abdominal organs. However, regardless of the primary cause, the imaging findings of bowel ischemia are similar. Furthermore, the bowel changes simulate inflammatory or neoplastic conditions. Understanding the pathogenesis of various conditions leading to mesenteric ischemia helps the radiologist recognize ischemic bowel disease and avoid delayed diagnosis, unnecessary surgery, or less than optimal management.

Breath-hold ultrafast three-dimensional gadolinium-enhanced MR angiography of the aorta and the renal and other visceral abdominal arteries

OBJECTIVES

The objectives of this study were to develop and show the efficacy of a breath-hold ultrafast three-dimensional (3D) spoiled gradient-echo (SPGR) gadolinium-enhanced MR angiographic technique for imaging the aorta and the renal and other visceral arteries of the abdomen; and to compare breath-hold ultrafast 3D SPGR with two-dimensional (2D) time-of-flight (TOF) and non-breath-hold ultrafast 3D SPGR in the same patients.

SUBJECTS AND METHODS

We prospectively studied the abdominal aorta and the renal and other visceral arteries 68 times in 63 consecutive patients with 2D TOF and ultrafast 3D SPGR MR angiography. Thirty-two patients had contrast angiography (n = 23) and/or surgery (n = 24) to serve as a gold standard. All MR imaging studies were performed on a 1.5-T scanner (General Electric Medical Systems, Milwaukee, WI) using an enhanced gradient system with maximum gradient strength of 2.3 gauss/cm reached in 150 microseconds. Axial 2D TOF parameters were: TR/TE, 33/5.5 msec; flip angle, 45 degrees; slice thickness, 2 mm; and no presaturation pulses. Coronal ultrafast 3D SPGR was performed before and after the i.v. administration of 40-60 cc of gadolinium. For the coronal ultrafast 3D SPGR, our parameters were: TR/TE, 4.8-7/1.1; flip angle, 60 degrees; 28-50 slices of 2.0-2.6 mm thickness; and acquisition time, 18-32 sec. Studies were read by a single radiologist [corrected] and were evaluated for the degree of stenosis in the renal, celiac, superior mesenteric, and inferior mesenteric arteries; any vascular anomalies (i.e., retroaortic renal veins and accessory renal or variant hepatic arteries) were noted.

RESULTS

Breath-hold ultrafast 3D SPGR correctly identified 31 of 31 stenoses of the renal artery for a sensitivity, specificity, and accuracy of 100%. Two-dimensional TOF detected 23 of 31 renal artery stenoses for a sensitivity, specificity, and accuracy of 74%, 98%, and 87% respectively. Breath-hold ultrafast 3D SPGR underestimated two renal arteries as having severe osteal stenoses that were graded correctly by 2D TOF and by angiography as occlusions. Eight of nine (89%) accessory renal arteries were correctly identified with breath-hold ultrafast 3D SPGR: Two-dimensional TOF identified six of nine (67%). Breath-hold ultrafast 3D SPGR identified one accessory and two reconstituted renal arteries missed by 2D TOF and conventional contrast angiography that were confirmed at surgery. Ultrafast 3D SPGR and 2D TOF correctly identified 20 of 20 celiac, superior mesenteric, and inferior mesenteric artery osteal stenoses or occlusions for a sensitivity, specificity, and accuracy of 100%. Three Riolan's arcs were correctly identified by breath-hold 3D SPGR but were missed by 2D TOF: Forty of the 63 patients did not have conventional contrast angiography and were managed surgically (n = 9) or medically (n = 31) based on the results of the MR angiograms and clinical data. Breath-hold ultrafast 3D SPGR MR angiography correctly identified and graded 48 of 51 renal, celiac, superior mesenteric, and inferior mesenteric artery stenoses or occlusions. Two-dimensional TOF MR angiography correctly identified and graded 45 of 51 renal, celiac, superior mesenteric, and inferior mesenteric artery stenoses and occlusions.

CONCLUSION

Breath-hold ultrafast 3D SPGR when combined with 2D TOF accurately identified and graded all (51 of 51) renal, celiac, superior mesenteric, and inferior mesenteric artery stenoses or occlusions.

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.

Embolic potential of left ventricular thrombus after myocardial infarction: a two-dimensional echocardiographic study of 119 patients

Left ventricular thrombus complicating myocardial infarction was diagnosed by two-dimensional echocardiography in 119 patients. The infarct site was anterior in 98 patients and inferior in 11. Systemic embolism occurred in 26 patients (stroke in 18, lower limb embolism in 7 and mesenteric embolism in 1). A protruding configuration of the thrombus was more common in the patients with embolism than in those without (23 [88%] of 26 versus 17 [18%] of 93) (p less than 0.01). Free mobility of the thrombus was found in 15 (58%) of 26 and 3 (3%) of 93 cases, respectively (p less than 0.01). In predicting embolism, protruding thrombus configuration had a sensitivity of 88% and a specificity of 82%, and positive and negative predictive accuracy was 57 and 96%, respectively. For free mobility of the thrombus, sensitivity was 58%, specificity 97%, positive predictive accuracy 85% and negative predictive accuracy 89%. In the 46 patients whose echocardiogram was obtained during the hospital admission for the index infarct, repeat echocardiograms were obtained during oral anticoagulant therapy. Twelve of these 46 patients had embolism and 2 of the 12 died. In seven of these patients, full dose oral anticoagulant therapy had been given before embolism occurred and in five it was started after an embolic event. The thrombus decreased in size or disappeared in six patients; in four the thrombus showed no change, and in two of these four emboli recurred despite anticoagulation. It is concluded that two-dimensional echocardiography may help delineate the embolic potential of left ventricular thrombus complicating myocardial infarction and may be of value in weighing the benefits and disadvantages of oral anticoagulant therapy.

Mesenteric venous thrombosis

MVT is an uncommon form of visceral ischemia. Symptoms and signs of MVT are usually nonspecific and should not be relied on for accurate diagnosis. A simple, logical diagnostic algorithm can be used to manage most of these patients (Fig. 6). CT or MRI appears to be the most sensitive diagnostic test and should be obtained early for any patient suspected of harboring MVT. Patients with peritonitis require prompt abdominal exploratory laparotomy to rule out ischemic bowel. Once the diagnosis of acute MVT is confirmed, the patient should be anticoagulated with heparin. During operation, all nonviable bowel should be resected with intent for a second-look laparotomy after 24 hours if there is any question of ongoing ischemia. We recommend using fluorescein-assisted evaluation of marginally viable bowel intraoperatively. After the operation, anticoagulation is continued with heparin and then oral warfarin sodium when the patient's bowel function returns. For those patients without peritonitis, we recommend prompt anticoagulation followed by at least a 48- to 72-hour period of close observation. All patients who have had an episode of acute MVT and do not have a contraindication to anticoagulation should be anticoagulated on a life-long basis with warfarin sodium. Despite our increased awareness of acute MVT, the 30-day mortality rate remains high. Acute MVT typically has a more insidious and unpredictable course than do other forms of visceral ischemic syndromes, with a mortality rate as high as that of its arterial counterpart. Although there has been a slight improvement in survival during the last 20 years, the recurrence rate remains high and the long-term prognosis is poor in this group of patients. Survival of patients with chronic MVT is better than that of those with acute MVT and appears to be determined by the underlying disease.

Mesenteric venous thrombosis: a changing clinical entity

OBJECTIVE

Mesenteric venous thrombosis (MVT) and its clinical spectrum have become better defined following improvements in diagnostic imaging. Historically, MVT has been described as a morbid clinical entity, but this may not necessarily be true. Often, an underlying disease process that predisposes a patient to MVT can be found and potentially treated. This study was designed to evaluate the diagnostics and management of MVT and to review long-term results of treatment.

PATIENTS

Thirty-one patients in whom MVT was diagnosed between 1985 and 1999 were retrospectively reviewed. Survivors were contacted for follow-up. There were 15 men and 16 women. Ages ranged from 22 to 80 years (mean, 49.1 years). Thirteen patients had documented hypercoagulability, 10 had a history of previous abdominal surgery, 6 had a prior thrombotic episode, and 4 had a history of cancer. MVT presented as abdominal pain (84%), diarrhea (42%), and nausea/vomiting (32%). Computed tomography (CT) was considered diagnostic in 18 (90%) of 20 patients who underwent the test. CT diagnosed MVT in 15 (100%) of 15 patients presenting with vague abdominal pain or diarrhea. Angiography demonstrated MVT in only five (55.5%) of nine patients.

RESULTS

Seven of 31 patients died within 30 days (< 30-day mortality rate, 23%). Twenty-two patients (72%) were initially treated with heparin. Nine patients were not heparinized: four of them died, and two were later given warfarin sodium (Coumadin). Of the 31 patients, only one received lytic therapy. Three patients became symptom free without anticoagulation. Ten patients (32%) underwent bowel resection. Overall, 19 (79%) of 24 survivors were treated with long-term warfarin therapy. Long-term follow-up was obtained in 24 patients (mean, 57.7 months). Twenty-one (88%) of 24 survived in follow-up.

CONCLUSION

The diagnosis of MVT should be suspected when acute abdominal symptoms develop in patients with prior thrombotic episodes or a documented coagulopathy. CT scanning appears to be the primary diagnostic test of choice. Anticoagulation is recommended. If diagnosed and treated early, MVT is not likely to progress to gangrenous bowel. Recent mortality rates for MVT are lower than previously published, perhaps because of earlier diagnosis and aggressive treatment or possibly because we now readily diagnose a more benign form of the disease, which is due to widespread use of CT scanning.

Mesenteric artery bypass: objective patency determination

PURPOSE

Many authors have reported extended relief of intestinal ischemia by use of a variety of reconstructive techniques, but all have relied on symptomatic follow-up. None have objectively measured patency rates. The purpose of this study was to determine the primary patency rates of bypass grafts placed for acute and chronic splanchnic atherosclerotic occlusive disease with use of objective follow-up with mesenteric duplex ultrasound scanning or arteriography.

METHODS

Twenty-five consecutive patients (mean age 61, female/male ratio of 2.7:1) who underwent placement of 38 splanchnic bypass grafts (29 saphenous vein grafts, 9 polytetrafluoroethylene) (22 retrograde, 16 antegrade) for ischemic symptoms (9 acute ischemia: 16 chronic ischemia) between 1984 and 1994 were monitored with either duplex scanning (30 grafts) or arteriography. Life-table and log rank analysis were used to determine and compare graft patency.

RESULTS

Three patients (12%, 2 acute ischemia and 1 chronic ischemia) died after operation. Six patients (30%) had significant morbidity (4 acute ischemia and 2 chronic ischemia). During follow-up from 1 to 136 months (mean 35 months), no patient died of bowel infarction or required revision for recurrent symptoms. Objective testing revealed three graft occlusions. Symptomatic follow-up had a sensitivity of only 33% for graft occlusion when compared with objective measurement. The life-table primary patency rate was 89% at 72 months. Life-table survival for the same patients was 75% at 36 months. Patency rates for antegrade (93% at 36 months) versus retrograde (95% at 36 months) bypass and saphenous vein grafts (95% at 36 months) versus polytetrafluoroethylene (89% at 36 months) were not significantly different (p = 0.47 and 0.43, respectively). Late patency rates of grafts placed for acute ischemia (92% at 36 months) versus chronic ischemia (89% at 36 months) were not significantly different (p = 0.77).

CONCLUSION

Splanchnic bypass for mesenteric ischemia, with a primary patency rate of 89% at 72 months, is an extremely durable form of revascularization. Long-term patency of grafts placed for acute ischemia does not differ significantly from that of bypasses for chronic occlusion. Duplex scanning allows standardized objective periodic follow-up of splanchnic reconstruction. Objective assessment is critical to accurately measure visceral revascularization patency rates.

Acute occlusive mesenteric ischemia: surgical management and outcomes

Acute mesenteric ischemia secondary to arterial occlusion (AMI) remains a highly lethal condition. To examine recent trends in management and associated outcomes, we examined our institutional experience over a recent 10-year period. All patients treated for AMI between January 1990 and January 2000 were identified (76 patients, 77 cases) and their medical records examined. At presentation, 64% demonstrated peritonitis and 30% exhibited hypotension. The interval from symptom onset to treatment exceeded 24 h in 63% of cases. Etiology was mesenteric thrombosis in 44 patients (58%) and embolism in 32 patients (42%). Thirty-five patients (46%) had prior conditions placing them at high risk for the development of AMI including chronic mesenteric ischemia (n = 26) and inadequately anticoagulated chronic atrial fibrillation (n = 9). Surgical management consisted of exploration alone in 16 patients, bowel resection alone in 18 patients, and revascularization in 43 patients, including 28 who required concomitant bowel resection. Overall, intestinal necrosis was present in 81% of cases. Perioperative mortality was 62% and long-term parenteral nutrition (TPN) was required in 31% of survivors. Peritonitis (odds ratio [OR] 9.4, 95% confidence interval [CI] 1.6, 54.0; p = 0.012 and bowel necrosis (OR 10.4, CI 1.9, 56.3; p = 0.007) at presentation were independent predictors of death or survival dependent upon TPN. We conclude that AMI remains a highly lethal condition due in large part to advanced presentation and inadequate recognition and treatment of patients at high risk.

Acute mesenteric ischemia: updated guidelines of the World Society of Emergency Surgery

Acute mesenteric ischemia (AMI) is a group of diseases characterized by an interruption of the blood supply to varying portions of the intestine, leading to ischemia and secondary inflammatory changes. If untreated, this process may progress to life-threatening intestinal necrosis. The incidence is low, estimated at 0.09-0.2% of all acute surgical admissions, but increases with age. Although the entity is an uncommon cause of abdominal pain, diligence is required because if untreated, mortality remains in the range of 50%. Early diagnosis and timely surgical intervention are the cornerstones of modern treatment to reduce the high mortality associated with this entity. The advent of endovascular approaches in parallel with modern imaging techniques is evolving and provides new treatment options. Lastly, a focused multidisciplinary approach based on early diagnosis and individualized treatment is essential. Thus, we believe that updated guidelines from World Society of Emergency Surgery are warranted, in order to provide the most recent and practical recommendations for diagnosis and treatment of AMI.

Splenic and portal venous obstruction in chronic pancreatitis. A prospective longitudinal study of a medical-surgical series of 266 patients

The aim of this study was a prospective search for splenoportal venous obstruction (SPVO) in a medical-surgical series of 266 patients with chronic pancreatitis who were followed up a mean time of 8.2 years. SPVO was systematically searched for using ultrasonography and then confirmed by angiography or computed tomography. SPVO was found in 35 patients (13.2%) but was symptomatic in only two. Initial obstruction involved the splenic vein in 22 patients, the portal vein in 10, and the superior mesenteric vein in three. Since venous obstruction extended from the splenic to the portal vein in five patients, the prevalence of portal obstruction was 5.6% (15/266). Acute pancreatitis and pseudocysts were the probable cause of SPVO in 91.4% of our cases. Half the cases of splenic venous obstruction were related to pseudocysts of the caudal pancreas. Esophageal varices were found in two patients and gastric varices in four at the time of diagnosis and during follow-up. At the end of follow-up, 12 patients had undergone splenopancreatectomy (N = 11) or splenectomy (N = 1). Only one patient was operated on for massive esophageal variceal bleeding, and another patient died due to intractable colic variceal bleeding. In four of six patients operated on with portal vein obstruction, surgery was difficult due to venous collaterals. Ten patients were not operated on and 13 patients operated on were not treated for SPVO. The mean follow-up after diagnosis of SPVO for these final 23 patients was 28.9 months. None of these patients bled.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Mesenteric venous thrombosis

The prevalence of mesenteric venous thrombosis has increased over the past 2 decades with the routine use of contrast-enhanced computed tomography (CT) in patients presenting with abdominal pain and those with portal hypertension. Concurrent with increasing recognition, routine and frequent use of anticoagulation has reduced the need for surgical intervention and improved outcome in these patients. Acute thrombosis often presents with abdominal pain, whereas chronic disease manifests either as an incidental finding on CT or with features of portal hypertension. Contrast-enhanced CT diagnoses about 90% of cases. The presence of collateral circulation and cavernoma around a chronically thrombosed vein differentiates chronic from acute disease. The superior mesenteric vein is often involved, whereas involvement of the inferior mesenteric vein is rare. Associated portal venous thrombosis can be seen if the disease originates in the major veins instead of the small vena rectae. Thrombophilia and local abdominal inflammatory conditions are common causes. Management is aimed at preventing bowel infarction and recurrent thrombosis. Anticoagulation, the mainstay of management, has also been safely used in patients with cirrhosis and portal hypertension. This review discusses the pathogenesis of thrombosis of mesenteric veins, the diagnosis and differentiation from arterial ischemia, the emergence of the JAK2 (Janus kinase 2) sequence variation as a marker of thrombophilia and myelodysplastic neoplasms, and new anticoagulants. Algorithms for the management of acute and chronic mesenteric venous thrombosis are provided to help readers understand and remember the approach to the management of acute and chronic mesenteric venous thrombosis.

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.

Mesenteric venous thrombosis: diagnosis and noninvasive imaging

Mesenteric venous thrombosis is an uncommon but potentially lethal cause of bowel ischemia. Several imaging methods are available for diagnosis, each of which has advantages and disadvantages. Doppler ultrasonography allows direct evaluation of the mesenteric and portal veins, provides semiquantitative flow information, and allows Doppler waveform analysis of the visceral vessels; however, it is operator dependent and is often limited by overlying bowel gas. Conventional contrast material-enhanced computed tomography (CT) allows sensitive detection of venous thrombosis within the central large vessels of the portomesenteric circulation and any associated secondary findings; however, it is limited by respiratory misregistration, motion artifact, and substantially decreased longitudinal spatial resolution. Helical CT and CT angiography, especially when performed with multi-detector row scanners, and magnetic resonance (MR) imaging, particularly gadolinium-enhanced MR angiography, enable volumetric acquisitions in a single breath hold, eliminating motion artifact and suppressing respiratory misregistration. Helical CT angiography and three-dimensional gadolinium-enhanced MR angiography should be considered the primary diagnostic modalities for patients with a high clinical suspicion of mesenteric ischemia. Conventional angiography is reserved for equivocal cases at noninvasive imaging and is also used in conjunction with transcatheter therapeutic techniques in management of symptomatic portal and mesenteric venous thrombosis.

Acute mesenteric venous thrombosis: case for nonoperative management

OBJECTIVE

Initial treatment in the management of acute mesenteric vein thrombosis (MVT) is controversial. Some authors have proposed a surgical approach, whereas others have advocated medical therapy (anticoagulation). In this study, we analyzed and compared the results obtained with surgical and medical treatment to determine the best initial management for this disease.

METHODS

We retrospectively reviewed the records of patients treated for MVT in a secondary care surgical department from January 1987 to December 1999. Before January 1995, our departmental policy was to perform surgery in patients with suspected MVT. Since January 1995, we have preferred a medical approach when achievable. Each patient in this study was assessed for diagnosis, initial management (laparotomy or anticoagulation), morbidity, mortality, duration of hospitalization, the need for secondary operation, portal hypertension, and survival rates.

RESULTS

Twenty-six patients were treated, 14 before January 1995 (group 1) and 12 since January 1995 (group 2). Morbidity, mortality, secondary operation, portal hypertension, and 2-year survival rates were 34.6%, 19.2%, 15.3%, 19.2%, and 76.9%, respectively. No statistical difference was observed between the two groups. The mean duration of hospitalization was 51.6 days in group 1 and 23.2 days in group 2 (P < .05). Among the 12 patients treated by means of laparotomy with bowel resection, 10 patients (83%) had mucosal necrosis without transmural necrosis at pathologic study.

CONCLUSION

Nonoperative management for acute MVT is feasible when the initial diagnosis with a computed tomography scan is certain and when the bowel infarction has not led to transmural necrosis and bowel perforation. The morbidity, mortality, and survival rates are similar in cases of surgical and nonoperative management. The length of hospital stay is shorter when patients are treated with a nonoperative approach. A nonoperative approach, when indicated, avoids the resection of macroscopically infarcted small bowel (without transmural necrosis) in cases that are potentially reversible with anticoagulation alone.

Acute mesenteric ischemia caused by spontaneous isolated dissection of the superior mesenteric artery: treatment by percutaneous stent placement

Spontaneous and isolated dissection of the superior mesenteric artery is a rare and often fatal event which has been successfully treated by surgery in several reported cases. We present a patient with acute mesenteric ischemia due to superior mesenteric artery dissection who was successfully treated by percutaneous endovascular placement of a Wallstent.

Modern treatment of acute mesenteric ischaemia

BACKGROUND

Diagnosis of acute mesenteric ischaemia in the early stages is now possible with modern computed tomography (CT), using intravenous contrast enhancement and imaging in the arterial and/or portal venous phase. The availability of CT around the clock means that more patients with acute mesenteric ischaemia may be treated with urgent intestinal revascularization.

METHODS

This was a review of modern treatment strategies for acute mesenteric ischaemia.

RESULTS

Endovascular therapy has become an important alternative, especially in patients with acute thrombotic superior mesenteric artery (SMA) occlusion, where the occlusive lesion can be recanalized either antegradely from the femoral or brachial artery, or retrogradely from an exposed SMA after laparotomy, and stented. Aspiration embolectomy, thrombolysis and open surgical embolectomy, followed by on-table angiography, are the treatment options for embolic SMA occlusion. Endovascular therapy may be an option in the few patients with mesenteric venous thrombosis who do not respond to anticoagulation therapy. Laparotomy is needed to evaluate the extent and severity of visceral organ ischaemia, which is treated according to the principles of damage control surgery.

CONCLUSION

Modern treatment of acute mesenteric ischaemia involves a specialized approach that considers surgical and, increasingly, endovascular options for best outcomes.

Clinical implications for the management of acute thromboembolic occlusion of the superior mesenteric artery: autopsy findings in 213 patients

OBJECTIVE

To study findings at autopsy in patients with fatal acute thromboembolic occlusion of the superior mesenteric artery (SMA).

SUMMARY BACKGROUND DATA

Acute occlusion of the SMA is difficult to diagnose and mortality remains high. In Malmo, Sweden, the autopsy rate between 1970 and 1982 was 87%, creating possibilities for a population-based study.

METHODS

Among 23,496 clinical autopsies and 7569 forensic autopsies, 213 cases with acute thromboembolic occlusion of the SMA and intestinal infarction were identified.

RESULTS

A clinical suspicion of intestinal infarction was documented in 32% of the patients, only 35% being in the care of surgeons. The embolus/thrombus ratio was 1.4 to 1. Thrombotic occlusions were located more proximally than embolic occlusions (P < 0.001), intestinal infarction was more extensive (P = 0.025) and thrombotic occlusions were associated with old brain infarction (P = 0.048), aortic wall thrombosis (P = 0.080), and disseminated cancer (P = 0.079). Patients with embolic occlusions (n = 122) had a higher frequency of acute myocardial infarction (AMI) than patients with thrombotic occlusions (P = 0.049). The embolic source was identified in 80%. In 115 (94%), synchronous embolism and/or source of embolus were present. There were findings of remaining cardiac thrombi in 58 (48%) and synchronous emboli affected 273 other arterial segments in 83 (68%).

CONCLUSIONS

Early recognition and revascularization would have been a prerequisite for survival in at least half of the patients, since the jejunum, ileum, and colon were affected by infarction. A minority of all patients were under surgical care. AMI, cardiac thrombi, and synchronous emboli were common findings among patients with embolic occlusions.

Detection of thrombosis in the portal venous system: comparison of contrast-enhanced MR angiography with intraarterial digital subtraction angiography

PURPOSE

To determine whether intraarterial digital subtraction angiography (DSA) can be replaced by contrast material-enhanced magnetic resonance (MR) angiography in the assessment of patency or thrombosis of the portal venous system in patients with portal hypertension.

MATERIALS AND METHODS

Thirty-six patients with portal hypertension underwent contrast-enhanced MR angiography and intraarterial DSA for assessment of the portal venous system. The images were evaluated for vessel patency or thrombosis of the portal, splenic, or superior mesenteric vein.

RESULTS

Of the 101 vessels evaluated, 42 were thrombosed. Overall sensitivity, specificity, and accuracy for the detection of thrombosis were 100%, 98%, and 99%, respectively, for MR angiography and 91%, 100%, and 96%, respectively, for DSA; differences between the imaging methods were not statistically significant. Only in four patients with six vessels (6%) were there discordant findings between MR angiography and DSA.

CONCLUSION

Noninvasive contrast-enhanced MR angiography has the potential to replace intraarterial DSA as the standard method to assess the whole portal venous system.

The surgical management of acute occlusion of the superior mesenteric artery

A study of 103 cases of acute occlusion of the superior mesenteric artery is presented. The relation of site of occlusion to etiology, extent of infarction, and survival following resection and revascularization is described. Included is an analysis of the technical factors contributing to successful revascularization, the specific complications of revascularization, and the application of elective second look operations and angiographic techniques. The persistant high mortality (85% in this series) can probably be reduced but only by advances in these areas along with progress in the more general aspects of management of elderly patients with multiple system problems and failure.

Clinical significance of splanchnic artery stenosis

BACKGROUND

The clinical relevance of splanchnic artery stenosis is often unclear. Gastric exercise tonometry enables the identification of patients with actual gastrointestinal ischaemia. A large group of patients with splanchnic artery stenosis was studied using standard investigations, including tonometry.

METHODS

Patients referred with possible intestinal ischaemia were analysed prospectively, using duplex imaging, conventional abdominal angiography and tonometry. All results were discussed within a multidisciplinary team.

RESULTS

Splanchnic stenoses were found in 157 (49.7 percent) of 316 patients; 95 patients (60.5 percent) had one-vessel, 54 (34.4 percent) two-vessel and eight (5.1 percent) had three-vessel disease. Chronic splanchnic syndrome was diagnosed in 107 patients (68.2 percent), 54 (57 percent) with single-vessel, 45 (83 percent) with two-vessel and all eight with three-vessel stenoses. Treatment was undertaken in 95 patients, 62 by surgery and 33 by endovascular techniques. After a median follow-up of 43 months, 84 percent of patients were symptom free.

CONCLUSION

Gastric exercise tonometry proved crucial in the evaluation of possible intestinal ischaemia. Comparing patients with single- and multiple-vessel stenoses, there were significant differences in clinical presentation and mortality rates.