From the Guidelines
Mesenteric ischemia is a serious medical condition characterized by insufficient vascular supply to the small bowel, leading to tissue damage and potential necrosis, with a mortality rate that approaches 60% if left untreated 1. The pathophysiology of mesenteric ischemia involves several mechanisms depending on the type of ischemia.
Key Mechanisms
- In acute mesenteric ischemia, a sudden occlusion of blood vessels occurs, commonly due to embolism from cardiac sources, thrombosis in atherosclerotic vessels, or non-occlusive causes like low cardiac output states.
- The superior mesenteric artery is most commonly affected due to its anatomical angle of origin.
- When blood flow is restricted, oxygen delivery to intestinal tissues decreases, triggering anaerobic metabolism and lactic acid production.
- This leads to cellular damage, increased intestinal permeability, and bacterial translocation.
- As ischemia progresses, reactive oxygen species form during reperfusion, causing further tissue damage.
Chronic Mesenteric Ischemia
- In chronic mesenteric ischemia, gradual narrowing of vessels occurs, typically from atherosclerosis, allowing time for collateral circulation to develop.
- However, this compensatory mechanism becomes insufficient during increased metabolic demands like after meals, causing postprandial pain.
- Without intervention, persistent ischemia leads to intestinal infarction, perforation, peritonitis, sepsis, and potentially death, highlighting the importance of early recognition and treatment 1.
Importance of Early Recognition
The importance of early recognition and treatment of mesenteric ischemia cannot be overstated, as delays in diagnosis and intervention can lead to life-threatening bowel infarction with associated mortality rates that approach 60% 1.
Diagnostic Approaches
Imaging techniques such as CT of the abdomen and pelvis, and MR angiography (MRA) can be used to identify the underlying cause of ischemia, evaluate for possible bowel complications, and exclude other potential diagnoses of acute abdominal pain 1.
Treatment Options
Treatment options for mesenteric ischemia include endovascular approaches and open surgery, with the choice of treatment depending on the chronicity, etiology, and degree of concern for bowel infarction 1. Prompt diagnosis and intervention are essential to reduce the mortality rates that exceed 50% 1.
From the Research
Pathophysiology of Mesenteric Ischaemia
The pathophysiology of mesenteric ischaemia is complex and involves a critical reduction in intestinal blood flow, which can result in bowel necrosis and high mortality 2. Mesenteric ischaemia can be caused by various factors, including:
- Embolism: a blockage of the superior mesenteric artery by a blood clot or other foreign material 3, 4
- Thrombosis: a blockage of the superior mesenteric artery by a blood clot that forms in the artery itself 3, 4
- Non-occlusive mesenteric insufficiency: a reduction in blood flow to the intestines without a physical blockage of the artery 3, 4
- Venous mesenteric ischemia: a blockage of the mesenteric veins, which can cause blood to back up into the intestines and lead to ischemia 3
Risk Factors
Mesenteric ischaemia is associated with several risk factors, including:
Clinical Presentation
The clinical presentation of mesenteric ischaemia can vary depending on the underlying cause and severity of the condition. Common symptoms include:
Diagnosis
Diagnosis of mesenteric ischaemia can be challenging, but it is essential to make a prompt diagnosis to reduce mortality. Diagnostic tests include:
- Laboratory tests: such as leukocytosis and elevated lactate 3
- Imaging tests: such as triple phase computed tomography with non-contrast, arterial, and delayed phases 3, 5, 6
- Angiography: to establish the diagnosis and plan treatment 5, 6, 2, 4
Treatment
Treatment of mesenteric ischaemia depends on the underlying cause and severity of the condition. Treatment options include: