The mortality in patients with AMI remains high despite the diagnostic, surgical and endovascular developments in recent decades. There was a decline in mortality rate from 80–100 % in the 1970s to 50–70 % in the last decade. The decrease has been attributed to the better management of diagnosis and therapy . The cause of visceral ischemia is an important factor. The mortality rate after surgical therapy for arterial embolism (54.1 %) and venous thrombosis (32.1 %) in a meta-analysis of Schoots et al.  was very high. This number rose after surgical treatment for arterial thrombosis (77.4 %) and NOMI (72.7 %). In our study, the 30-day mortality rate was 30.8 %. Decisive factors that contribute to the severity of the disease are a late diagnosis, the resulting delay in vascular therapy and the pre-existing co-morbidities of many patients. An early diagnosis, prior to the development of bowel necrosis with peritonitis, is one of the most important prognostic factors . Statistical analysis of the delay interval did not reveal statistical significance on survival in our study because of the low number of cases (n = 34).
CT scanning with contrast agents is the current gold standard in instrument-based diagnostic testing, providing both high sensitivity and specificity. In contrast and despite its high sensitivity and specificity, MRI requires further development because of the longer duration of the investigation and its low availability. It therefore plays only a minor role in the diagnosis of peripheral embolisms of the SMA, NOD and of acute mesenteric ischemia [7, 8].
In cases of suspected AMI, the emergency diagnosis should include biphasic contrast computed tomography (CECT) with multi-planar reconstruction at 3 levels. The venous phase of the CT is necessary for the diagnosis of mesenteric vein thrombosis . In our study, CT with contrast agents was the gold standard in instrument-based diagnostic testing, having replaced conventional angiography as our imaging modality of choice.
Non-specific serum lactate is often used as a diagnostic parameter. An elevated lactate level (>2.2 mmol/l) reflects the late phase of AMI with a transmural bowel infarction, where release of lactate into the bloodstream is caused by anaerobic metabolism with bacterial translocation. Serum lactate, however, cannot detect the early phase where there is only damage to the intestinal mucosa [10, 11]. Another serum parameter that can be used for diagnosis is the D-dimer, which, although sensitive to the early phase, has very low specificity .
As future biomarkers for the early phase of AMI, intestinal fatty acid-binding protein (I-FABP), α-glutathione S-transferase (GST) and D-lactate may play an important role. I-FABP and GST are localized in the small intestinal mucosa, whereas D-lactate is a natural degradation product of intestinal bacteria. These markers may appear early in the bloodstream if damage to the mucosa of the small intestine occurs, leading to a loss of enterocytes as the first sign of ischemia. However, the reliability of these serum markers has yet to be demonstrated in randomized controlled prospective studies . In our daily clinical practice we used only L-lactate, leukocytosis and C-reactive protein as parameters for AMI. Biochemical markers, such as I-FABP, GST and D-lactate, must be further studied to determine their roles as valid biomarkers for AMI, and therefore, they cannot be used in daily clinical practice [11, 12]. L-lactate, currently the most commonly used marker, is not specific enough, however, and is only present during the late phase of AMI .
In a thrombectomy or embolectomy, the thrombus is recovered through a transaortic or transmesenteric arteriotomy. The arterial occlusion is closed by either direct suture or vein patch depending on the vessel diameter. As atherosclerotic plaques cause occlusion of the visceral arteries, these plaques can be removed either indirectly transaortally or directly via an open endarterectomy (TEA). Surgical access can be performed by a laparotomy or through a thoracoabdominal approach . An SMA transposition can be used for short segment stenosis and occlusions of the SMA. Here, the artery is discontinued and reinserted further distally into the infrarenal aorta .
On the other hand, in cases of stenoses extending to a large portion of the vessel wall, the bypass procedure is the method of choice. The great saphenous vein or an alloplastic material (PTFE, Dacron) are available as bypass materials that may be applied antegrade or retrograde. In the retrograde procedure, where the origin of the bypass is located distal to the SMA, the vessel substitutes should be guided behind the left renal vessels. The renal vessels serve as a fulcrum to prevent kinking of the bypass. Due to its complex correct anatomic description, this bypass is called the “French bypass”. The “French bypass” combines the advantages of ante- and retrograde visceral bypasses. The procedure allows distal segments of the SMA to be reconstructed [16–18]. If the lumen of the SMA is occluded due to a dissection membrane that separates the true from the false lumen, the membrane can be resected transaortally following direct suturing of the aorta. In our center, we used all of these surgical procedures (Table 1) and saw the best results for transposition, with a primary patency rate of 80 %. Overall, there was no significant relationship between the choice of the bypass and the choice of the material used in terms of survival. The results from the first case series of 64 patients (1979–2000) were published in 2002 . Compared to our 2002 study , no difference in terms of age, gender, risk profile or cause of occlusion could be found in the present work. However, the new study showed a reduction in the overall mortality rate, from 67 to 30 %, due to the improved management of the diagnostic and treatment options.
The modern treatment of AMI should primarily be performed by revascularization of the intestine.
A visceral surgical operation with bowel resection of necrotic parts can be performed afterwards. In modern vascular surgery, both endovascular and open surgical treatment options should be considered.
Preoperatively, both clinical and CT morphological aspects must be considered, whether the patient presents with peritonitis or an embolic or thrombotic occlusion of the SMA. The endovascular treatment option is recommended only in patients without peritonitis .
In the case of an AMI in combination with peritonitis, exploratory laparotomy with vascular therapy is the method of choice.
Five non-randomized studies have reported a comparison between open and endovascular surgery. In a retrospective study conducted within a single center, no difference in mortality between the two methods could be shown . However, another study reported lower morbidity and mortality using the endovascular method . Three other multicenter studies were national supra-regional studies: lower rates of bowel resection and lower mortality and morbidity were seen in these studies for the endovascular method [21, 22]. Therefore, if endovascular therapy appears to be possible, this method should be carried out whenever possible after the physician has excluded peritonitis.
Open surgery can also be used in patients with peritonitis in the late phase of AMI.
The poorer outcomes compared to endovascular procedures are due to the poorer conditions of a late phase AMI.
Our study is, however, limited by its retrospective nature and as a single center study in general validity.