Acute superior mesenteric artery embolism or thrombosis

　　Most emboli in acute superior mesenteric artery embolism or thrombosis originate from the heart, such as the left atrium of rheumatic heart disease and chronic atrial fibrillation, the left ventricle after acute myocardial infarction, or wall thrombi formed after previous myocardial infarction, endocarditis, valvular disease, or after valve replacement surgery, etc., and can also come from spontaneously detached ones, or from detachment caused by cardiovascular catheterization procedures.
　　The superior mesenteric artery branches off from the abdominal aorta at an acute angle, itself almost parallel to the aorta, and consistent with the main direction of blood flow, so emboli are prone to enter and form embolism. Acute superior mesenteric artery thrombosis almost always occurs at the original atherosclerotic stenotic site at the orifice, and is produced under the influence of certain triggers such as congestive heart failure, myocardial infarction, dehydration, sudden decrease in cardiac output, or blood volume reduction after major surgery, etc. It can also be caused by dissecting aneurysm, oral contraceptives, iatrogenic injury, etc.

　　The initial abdominal pain of acute superior mesenteric artery embolism or thrombosis is caused by intestinal spasm, followed by intestinal necrosis, and the pain becomes persistent. Most patients have frequent vomiting, with vomit resembling bloodwater. After 6-12 hours of onset, patients may develop paralytic ileus. In the late stage, toxic shock may occur.

　　Acute superior mesenteric artery embolism or thrombosis causes ischemia, so the majority of clinical manifestations of both are similar. Severe abdominal colic is the initial symptom, which is difficult to alleviate with general medication and can be generalized or located around the umbilicus, upper abdomen, lower right abdomen, or suprapubic area. The initial abdominal pain is caused by intestinal spasm, followed by intestinal necrosis, and the pain becomes persistent. Most patients have frequent vomiting, with vomit resembling bloodwater.

　　To prevent acute superior mesenteric artery embolism or thrombosis, the primary disease should be treated, such as valvular heart disease, atrial fibrillation caused by various reasons, myocardial infarction, and bacterial endocarditis, etc., to prevent embolism or thrombosis leading to the occurrence of this disease.

　　In the laboratory examination of acute superior mesenteric artery embolism or thrombosis, the white blood cell count is often over 20×10^9/L, serum amylase increases, and the serum lactate dehydrogenase (LDH) and its isoenzyme LD ratio, serum inorganic phosphorus all increase. Other auxiliary examinations mainly include:

　　1. Abdominal X-ray Early abdominal X-ray films may show small bowel distension; when the condition progresses to intestinal paralysis, small bowel and colonic distension, edema, and thickening of the intestinal wall can be seen; in intestinal necrosis, intestinal cavity gas leaks into the intestinal wall, accumulates subserosally, and the plain film shows a luminous band or luminous halo, and sometimes gas shadows can also be seen in the portal vein.

　　2. Angiography Patients suspected of having acute mesenteric ischemia should undergo early angiography regardless of abdominal signs after plain films exclude other acute abdominal conditions. Because this not only can differentiate whether the occlusion of large blood vessels is caused by thrombosis or embolism, but also diagnose non-occlusive ischemia, the degree and extent of vascular stenosis.

　　3. CT examination This examination can directly display blood clots in the intestinal wall and blood vessels, which is superior to X-ray films and barium examination.

　　4. Doppler ultrasound This examination can measure the blood flow of the portal vein and superior mesenteric vein, which has certain diagnostic value for judging the formation of thrombosis in the blood vessels.

　　5. Radioisotope examination Using monoclonal antibodies labeled with radioactive indium or technetium, after injection into the human body, γ photography can show the ischemic area of acute mesenteric occlusion. At present, this technology has been gradually used in clinical practice, and it is estimated to have a good development prospect.

　　Patients with acute superior mesenteric artery embolism or thrombosis should fast during the surgical period. After surgery, attention should be paid to soft food, low-salt, and low-fat diet. Avoid spicy, cold and cool foods, and avoid the stimulation of smoking and alcohol.

　　Patients with acute mesenteric ischemia mainly have complications from cardiovascular diseases, and acute superior mesenteric artery occlusion will worsen cardiovascular diseases, therefore, it should be placed on the same important position to improve heart function and the overall condition of the patient. While taking measures such as actively treating shock, anti-infection, correcting acidosis, maintaining electrolyte balance, and strengthening nutritional support, it is necessary to perform surgery and exploration as soon as possible without losing sight of one aspect while neglecting another.
　　When an embolism is found in a branch or the distal end of the trunk during exploratory laparotomy, and there is a small range of intestinal ischemia and necrosis has occurred, partial intestinal resection and anastomosis can be performed. In cases where the small area of intestinal necrosis does not affect intestinal function after resection, the range of intestinal resection can be appropriately widened. For partial point-like necrosis of the intestinal tract, the normal serosal and muscular layers at the upper and lower ends of the necrosis can be sutured, and the necrotic part can be flipped into the intestinal lumen. However, when there is a large area of irreversible necrosis in the intestinal tract, it is more beneficial to quickly remove the necrotic intestinal loops to reduce the absorption of toxins. Active treatment should be given according to short bowel syndrome after surgery.