Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_999_Библиотеки_им_академика_М_И_Перельмана

Acute mesenteric ischemia (AMI) is a sudden, severe decrease in blood ow to the intestines due to thrombosis or embolism and is considered a medical emergency requiring urgent intervention. If left untreated, acute mesenteric ischemia can prog­ress to bowel infarction, perforation, and sepsis. Globally, the incidence of AMI is rare, estimated to be 0.1–0.2% of all hospital admissions; however, certain surgical procedures especially with prolonged hypotension are precipitating mechanisms, of the non-occlusive modality however encompassing thrombosis as well. Mortality rate depends on many factors, ranging from 10 to 50% [1–6]. Classic acute mesen­teric ischemia can result from various causes including thrombosis of the mesen­teric arteries due to atherosclerosis, embolism of cardiac or aortic origin, and arterial dissection. Vasospasm can be a contributing phenomenon. The most common cause of AMI is embolic occlusion usually from cardiac sources such as atrial brillation, myocardial infarction, or endocarditis [7, 8]. Thrombotic occlusion of the mesen­teric arteries can also cause AMI, usually in patients with underlying atherosclerosis or hypercoagulable states [9].

The clinical presentation of acute mesenteric ischemia is often abrupt, with patients experiencing some or all of the following: severe abdominal pain, nausea, vomiting, diarrhea, and bloody stools. The pain is usually out of proportion to the physical exam and is often described as cramping, colicky, or diffuse with associ­ated abdominal tenderness, rebound tenderness, and/or absent bowel sounds [10,

inammation such as fever, leukocytosis, and metabolic acidosis [12]. Imaging

The diagnosis of NOMI can be challenging as imaging studies may not show a clear obstruction in the mesenteric vessels [23]. Diagnosis is typically based on a high index of clinical suspicion, along with imaging ndings such as thickened bowel walls, decreased contrast enhancement, or pneumatosis intestinalis on CT scans [24].

Mesenteric venous ischemia is a condition in which a blood clot forms in one of the primary veins draining the intestines resulting in massive congestion within the mesenteric circulation. The superior mesenteric vein (SMV) is the most commonly affected vein in mesenteric venous thrombosis (MVT), accounting for approxi­mately two-thirds of cases; however, the portal vein is also commonly involved, either alone or in combination with the SMV [26]. The exact cause of MVT is often not clear, but risk factors can include hypercoagulable states, abdominal surgeries, inammatory bowel disease, pregnancy and the post-partum period, liver disease, pancreatitis, and certain medications [26–28].

Venous mesenteric ischemia can either present suddenly with severe diffuse abdominal pain or insidiously over the course of days to weeks [29]. Diagnosis requires a high index of suspicion given the patients history and physical exam, and typically requires a CTA with a dedicated venous phase, although a duplex ultra­sound scan can be performed in those that cannot undergo CTA [30].