Acute mesenteric ischemia
Last reviewed: 23.04.2024
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Acute mesenteric ischemia - a violation of blood circulation in the intestine, caused by embolism, thrombosis or a decrease in blood flow. This leads to the release of mediators, inflammation and, ultimately, a heart attack. The nature of abdominal pain does not correspond to the data of a physical examination.
Early diagnosis is difficult, but the most informative are angiography and diagnostic laparotomy; Other methods of research allow diagnosis only in the late stage of the disease. Treatment of acute mesenteric ischemia consists of embobectomy, revascularization of viable segments or resection of the intestine; Sometimes vasodilator therapy is effective. Mortality is high.
[What causes acute mesenteric ischemia?
The intestinal mucosa has a high level of metabolism and accordingly a high demand for good blood flow (approximately 20-25% of the minute heart volume), which creates an increased sensitivity of the intestine to a decrease in perfusion. Ischemia destroys the mucous barrier, creating conditions for the penetration of microflora, toxins and vasoactive mediators, which in turn lead to myocardial weakness, the syndrome of the systemic inflammatory response, multiple organ failure and death. The exit of mediators can occur even before the development of a full heart attack. Necrosis usually develops only 10-12 hours after the appearance of the initial signs.
The three main vessels provide blood supply to the abdominal cavity organs: the celiac trunk, the superior mesenteric artery (BWA) and the inferior mesenteric artery (NBA). The celiac trunk blood supply to the esophagus, stomach, proximal part of the duodenum, liver, gall bladder, pancreas and spleen. The superior mesenteric artery supplies the distal part of the duodenum, jejunum, ileum and colon to the splenic angle. The lower mesenteric artery supplies the descending, sigmoid colon and rectum. Collateral vessels are widely developed on the stomach, duodenum and rectum; these areas are rarely exposed to ischemia. The splenic corner represents the boundary of the blood supply between the BWA and the NBA and constitutes a certain risk of ischemia.
Mesenteric blood flow can be disturbed as a result of lesions of venous or arterial vessels. Typically, in patients older than 50 years and having a very high risk, the following types of occlusion and risk factors are observed.
- Arterial embolism (50%), risk factors: coronary artery disease, heart failure, heart valve lesions, atrial fibrillation, and arterial embolism in the anamnesis.
- Arterial thrombosis (10%), risk factors: systemic atherosclerosis.
- Venous thrombosis (10%), risk factors: hypercoagulation, inflammatory diseases (eg, pancreatitis, diverticulitis), trauma, heart failure, renal failure, portal hypertension and caisson disease.
- Non-occlusive ischemia (25%), risk factors: decreased blood flow (heart failure, shock, extracorporeal circulation) and abdominal vasospasm (vasopressors, cocaine).
However, many patients do not have known risk factors.
Symptoms of acute mesenteric ischemia
Early symptoms of mesenteric ischemia are severe pain in the abdomen, but with minimal physical examination data. The abdomen remains soft with little soreness or lack of it. Moderate tachycardia may be present. Later, with the development of necrosis, there are signs of peritonitis with abdominal tenderness, defensive muscle tension, stiffness and lack of peristalsis. The stool can be with blood (more likely with an increase in ischemia). Usually the symptoms of shock develop, and often the disease ends fatal.
Sudden development of pain is not a diagnostic sign, but allows for an arterial embolism, whereas a more gradual onset is characteristic of venous thrombosis. Patients with signs of postprandial discomfort in the abdomen in the anamnesis (which suggests intestinal angina) may have arterial thrombosis.
Diagnosis of acute mesenteric ischemia
Early diagnosis of acute mesenteric ischemia is especially important, since mortality increases significantly with the development of an intestinal infarction. Mesenteric ischemia should be assumed in any patient over 50 years of age with sudden severe abdominal pain, with known risk factors or predisposing diseases.
Patients with obvious abdominal symptoms of ischemia require laparotomy for treatment and diagnosis. In other cases, selective angiography of mesenteric vessels is the diagnostic method of choice. Other instrumental studies and blood tests may show changes, but they are not specific enough and informative in the early stages of the disease, when timely diagnosis is needed. Routine radiographic examinations of the abdominal cavity are useful mainly to exclude other causes of pain (eg perforation of the hollow organ), however, if the portal vein is damaged, gas or pneumatization of the intestine can be visualized. These signs are also revealed by CT, which can directly visualize the vascular occlusion - more precisely, the venous fragment. Doppler ultrasonography can sometimes identify arterial occlusion, but the sensitivity of the method is inadequate. MRI can accurately diagnose occlusion in the proximal part of the vessel, but the study is less informative for distal occlusion. Some biochemical parameters in the blood serum (eg, creatine phosphokinase and lactate ) increase with the development of necrosis, but they are nonspecific and later. The intestinal serum fatty acids associated with the protein may in the future prove to be a valuable early marker.
Treatment of acute mesenteric ischemia
If the diagnosis and treatment of acute mesenteric ischemia become possible before the infarction develops, the mortality is small; later, with the development of an intestinal infarction, the mortality rate approaches 70-90%.
If the diagnosis of "acute mesenteric ischemia" is established with diagnostic laparotomy, treatment options are possible - embobectomy, revascularization or bowel resection. If the diagnosis is verified with angiography, the infusion of the papaverine vasodilator through the angiographic catheter can improve blood supply, both in occlusive and non-occlusive etiology of ischemia. 60 mg of the drug is injected for 2 minutes, followed by an infusion of 30-60 mg / hour. Papaverine is effective enough before surgical intervention, and also during the operation and in the postoperative period. In addition, with arterial occlusion, thrombolysis or surgical embobectomy is possible. The development of abdominal symptoms during the diagnostic process involves the implementation of surgical intervention. Venous mesenteric thrombosis without signs of peritonitis requires infusions of papaverine followed by anticoagulant therapy, including heparin, and then warfarin.
Patients with arterial embolism or venous thrombosis require prolonged anticoagulant therapy with warfarin. Patients with non-occlusive ischemia can be treated with antiplatelet therapy.