Acute superior mesenteric artery infarction

Introduction to acute superior mesenteric artery infarction The cause of acute superior mesenteric artery infarction (acuteobstructionofthesuperiormesentericartery) is mostly cardiac emboli occlusion obstruction of the artery, or arteriosclerosis secondary to thrombus obstruction of the lumen, eventually leading to the corresponding tissue infarction, the severity depends on the arterial basal lesion, the speed of infarction, Degree and collateral circulation. basic knowledge The proportion of illness: 0.005% Susceptible people: no specific population Mode of infection: non-infectious complication:

Acute mesenteric artery infarction

(1) Causes of the disease

Vascular lesions and hypoperfusion are the two major factors that cause most acute superior mesenteric artery infarction, followed by bacterial infections. On the basis of extensive arteriosclerosis, it can also occur in dissecting aneurysms, systemic lupus erythematosus. On the basis of long-term oral contraceptives or hypercoagulable state, acute mesenteric ischemia, thrombosis or embolism is caused.

Vascular disease

Mainly atherosclerosis, arterial embolism or thrombosis, in addition to multiple nodular arteritis, rheumatoid arthritis, diabetes and other diseases also accompanied by arteritis of small blood vessels, lesions often involve the trunk of the superior mesenteric artery and Branches, sometimes occurring in small arteries, are most likely to occur within 2 cm of the opening of the abdominal aorta. The superior mesenteric artery is obliquely separated from the abdominal aorta. Therefore, the embolus in the systemic circulation easily enters the artery to form an embolism.

2. Insufficient perfusion

In patients with atherosclerotic stenosis, although the blood supply can maintain the normal activity of the intestine, the reserve capacity has been reduced. Any drop in blood pressure may lead to insufficient blood supply and infarction, especially in patients with dissection aneurysms. It is more likely to occur in diseases such as systemic lupus erythematosus.

3. Bacteria and bacterial toxins

Under normal circumstances, the intestinal flora maintains a dynamic balance, intestinal ischemia, intestinal wall defense ability is reduced, bacteria that invade the intestinal wall, can cause pseudomembranous colitis, postoperative enteritis, acute necrotic enteritis, acute hemorrhagic enteritis, etc. Animal experiments have shown that after intestinal ischemia, if antibiotics are added, the rate of shock in animals decreases.

(two) pathogenesis

The superior mesenteric artery branches to the intestine with terminal blood vessels. After the main infarction, the collateral branch can not be compensated. The thrombus occurs at the infarction and extends to the distal end. The intestinal ischemic fistula first occurs, and the intestinal wall is hypoxic after 1 to 2 hours. Edema occurs first in the mucosa, then spreads to the serosa layer, followed by embolization of the intestinal tract, capillaries in the intestinal wall, and even rupture, followed by ulceration and necrosis, and the muscular layer is poorly tolerant to hypoxia. The whole layer of the intestinal wall is necrotic. At this time, the intestinal wall has extensive hemorrhage, and a large amount of exudation in the intestinal lumen also penetrates into the abdominal cavity, resulting in a decrease in circulating blood volume; bacterial growth in the intestinal tract and penetration into the abdominal cavity, so that the exudate is carried Odor, severe intestinal necrosis, intestinal perforation and peritonitis, bacterial endotoxin absorption and hypovolemia, patients with shock, poor prognosis, deeper lesions without perforation, can be complicated by intestinal fibrosis and scar Formation, thickening of the intestinal wall, can occur stenosis.

Acute superior mesenteric artery infarction prevention

There is no effective preventive measure for this disease. Early detection and early diagnosis are the key to the prevention and treatment of this disease.

Acute superior mesenteric artery infarction Complication

Blurred consciousness, abdominal muscle tension

Acute mesenteric artery infarction symptoms Common symptoms Abdominal pain, bowel sounds, bloating, nausea and vomiting, peritonitis, ambiguity, tachycardia, dyspnea, tension, hypotension

Abdominal pain is the most common symptom, often a sudden diffuse umbilical pain, the patient's expression can be extremely painful, painkillers are often ineffective, can be accompanied by vomiting, diarrhea (often bloody diarrhea), difficulty breathing and confusion, such as With frequent intentions, it is a typical symptom of acute infarct mesenteric ischemia. Non-infarction ischemia has little intention or acute defecation. The early abdominal signs and symptoms are obviously not consistent, the abdominal muscles are not nervous, and the tenderness is not obvious. The bowel sounds can be normal or hyperthyroidism, but as the ischemia increases, the abdominal distension is obviously weakened, and muscle tension, tenderness and rebound pain appear. It is characterized by serositis and perforated peritonitis, which may be accompanied by fever. , tachycardia, hypotension, increased white blood cells and left nucleus; elevated serum in serum or peritoneal fluid, increased urinary phosphate excretion, often suggesting severe intestinal wall damage, acidosis in the late stage.

The clinical manifestations of superior mesenteric artery embolization vary with the location, extent, and collateral circulation of the superior mesenteric. Bergan suggests acute acute abdominal pain, organic heart disease, and strong gastrointestinal emptying symptoms (nausea, vomiting, or diarrhea). The triple sign of superior mesenteric artery embolism, abdominal pain is the most common symptom, often begins with sudden umbilical cramps, may be accompanied by increased heart rate, early bowel sounds can be hyperthyroidism, with intestinal ischemia, intestinal necrosis is aggravated, The bowel sounds weakened, abdominal pain increased, vomiting, abdominal distension, discharge of mucus and blood, fever and peritonitis. Finally, the disappearance of bowel sounds, dehydration and shock, suggesting that the lesions are irreversible.

Acute mesenteric artery thrombosis refers to the fact that the artery itself has a certain pathological basis, and thrombosis is formed under certain incentives. The main pathological basis is arteriosclerosis, and other aortic aneurysms, thromboangiitis obliterans, and nodular arteries Inflammation and rheumatoid vasculitis, etc., low blood volume or sudden drop in cardiac output, dehydration, arrhythmia, vasoconstrictor or excessive diuretics are common causes.

Superior mesenteric artery thrombosis occurs in the arterial opening and often involves the entire superior mesenteric artery. Therefore, the lesion can involve all small and right colons. If the thrombosis is more limited, the infarct size is smaller, because the superior mesenteric artery has been diagnosed before the onset. There are lesions, so the severity of abdominal pain after onset is often inferior to that of the superior mesenteric artery.

Examination of acute superior mesenteric artery infarction

The mesenteric artery embolization leukocytes often exceed 20 × 109 / L, serum amylase increased, CPK increased with the progress of the disease, 72h gradually recovered, serum lactate dehydrogenase (LDH) and its isozyme LD ratio, serum inorganic phosphorus Both have increased, aspartate aminotransferase (AST), lactate dehydrogenase (LDH) and CPK have a reference value for the diagnosis of superior mesenteric artery thrombosis.

1. Abdominal X-ray examination

Abdominal plain film can be seen in the small intestine in the early stage; when the disease progresses to intestinal paralysis, the small intestine, colonic flatulence, intestinal wall edema, thickening; intestinal gas leakage into the intestinal wall during intestinal necrosis, accumulate in the subserosal film, the flat piece can be seen through Light bands or light-transmissive rings, sometimes gas shadows are also visible in the portal vein.

Angiography

In patients with suspected acute mesenteric ischemia, the plain film excludes other acute abdomen. Regardless of the abdominal signs, angiography should be performed early. This can not only identify whether large vessel occlusion is caused by thrombosis or embolization, but also diagnosis. Non-occlusive ischemia, degree and extent of vascular stenosis.

The embolus tends to be embolized in the distal side of the main artery of the superior mesenteric artery or in the branch. The embolization is filled with contrast agent on the proximal side, and the distal vessel is not developed. The thrombus is usually within 3 cm of the initial part of the artery. Sudden interruption of blood vessels, may be associated with reactive vasoconstriction, the diameter of the tube is generally small, due to the formation of collateral circulation, so the distal end of the obstruction can have different degrees of filling; non-occlusive mesenteric ischemia mesenteric artery and its branches have Various manifestations: diffuse stenosis, localized stenosis at the beginning of most branches of the superior mesenteric artery, stenosis and dilation of the superior mesenteric artery branch, arterial arch, insufficient filling of blood vessels in the wall.

3. CT examination

It can directly display blood clots in the intestinal wall and blood vessels, which is superior to X-ray film and tincture examination.

4. Doppler ultrasound

It can measure the blood flow of portal vein and superior mesenteric vein, and has certain diagnostic value for judging intravascular thrombosis.

5. Radionuclide examination

Monoclonal antibodies labeled with radionuclide indium or strontium can be injected into the human body to perform gamma photography, which can show the ischemic area of acute mesenteric occlusion. At present, this technology has been gradually used in clinical practice, and it is estimated that there is a good development prospect.

Diagnosis and diagnosis of acute superior mesenteric artery infarction

Diagnostic criteria

The diagnosis method of this disease is mesenteric angiography, but in the following emergency cases, in order to avoid extensive necrosis of the intestine and life-threatening, laparotomy should be performed to restore the perfusion of the superior mesenteric artery in time.

1. Over 50 years of age with valvular heart disease, atrial fibrillation, recent myocardial infarction or embolism in other parts of the body, or a history of post-prandial colic (about 50% of patients with symptoms of chronic intestinal ischemia before onset).

2. Acute diffuse severe abdominal pain and mild abdominal signs.

Differential diagnosis

The disease mainly needs to be differentiated from ulcerative colitis, Crohn's disease, strangulated intestinal obstruction, etc., and its characteristics are:

1. The onset is sudden and the disease progresses rapidly.

2. Abdominal pain is accompanied by bloody stools.

3. There is often a history of cardiovascular disease.

4. The common indentation sign of barium enema is common in the spleen and adjacent intestines.

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