Chronic mesenteric ischemia: Clinical sciences
Introduction0:00–0:50
Chronic mesenteric ischemia, or CMI, occurs when there is a decrease of blood flow within the mesenteric vasculature. Mesenteric ischemia can affect either the small or large bowel, depending on the blood vessels involved, and is characterized by narrowing of these blood vessels due to atherosclerotic plaques.
The mesenteric vasculature has an extensive network of collateral vessels, which usually helps maintain perfusion in patients with atherosclerotic disease.
However, if one of the larger vessels is occluded, particularly the celiac artery and the superior mesenteric artery, or SMA, then patients typically become symptomatic.
Therefore, the diagnosis of CMI depends on first identifying the presence of stenosis with a duplex ultrasound, then assessing the severity of the occlusion with a CTA.Now, if you suspect chronic mesenteric ischemia, you should first perform an ABCDE assessment to determine if the patient is unstable or stable.
Unstable patient0:50–2:08
If the patient is unstable, you should initiate acute management to stabilize their airway, breathing, and circulation. This means you might need to obtain IV access, administer IV fluids, and begin empiric broad-spectrum antibiotics.Here’s a clinical pearl to keep in mind!
If you suspect CMI and your patient is unstable, be sure to evaluate for the possibility of bowel infarction due to acute-on-chronic mesenteric ischemia.
These patients often have sudden, severe abdominal pain and may have abdominal distension with guarding and rebound on exam.
An abdominal x-ray will show pneumatosis intestinalis, or gas within the intestinal wall, which indicates bowel infarction and necrosis; it may also show pneumoperitoneum, or gas in the abdominal cavity, which means that a perforation occurred.
These patients need emergent surgical consultation for exploratory laparotomy, which will be both diagnostic and therapeutic.
Remember, the only treatment for a necrotic bowel is surgical resection.Okay, now that we covered how to approach unstable patients, let’s go back to the ABCDE assessment and discuss how to manage stable patients.
Stable patient2:08–4:04
If the patient is stable, you should first obtain a focused history and physical exam, as well as labs. Be sure to order lactate levels, which can help you determine whether or not there’s tissue hypoxia.
Patients often report postprandial crampy abdominal pain, since the gut has a higher demand for perfusion after eating. This pain is also known as intestinal angina, and usually starts about 30 minutes after eating and resolves within one to three hours.
The abdominal pain can be so profound, it can progress to food “fear”, or aversion, and eventually result in unintentional weight loss!
Keep in mind that your patient may also have nonspecific complaints, such as nausea and vomiting, as well as diarrhea or constipation.
Finally, history is often positive for tobacco use, hypertension, and other forms of atherosclerosis, such as peripheral vascular disease or coronary artery disease.
On the other hand, physical exam could reveal diffuse abdominal tenderness, but often this finding can be completely absent.
Also, there’s no rebound tenderness or guarding, but there’s typically abdominal distension and epigastric bruit on auscultation.
Finally, on labs, lactate levels will usually be elevated. Here’s another clinical pearl!
Because patients with CMI typically present with abdominal pain and weight loss, the work up usually starts with an EGD and colonoscopy to rule out malignancy.
Therefore, if your patient is still symptomatic despite inconclusive initial testing, keep a high index of suspicion for CMI to prevent any further delay in diagnosis and treatment.
At this point, you should suspect chronic mesenteric ischemia, so your next step is to order a duplex ultrasound. If the duplex ultrasound does not show stenosis of a mesenteric artery, you should consider an alternative diagnosis.
Duplex US & CTA4:04–5:21
On the other hand, if the duplex ultrasound shows stenosis of a mesenteric artery, order a CTA, which can help you confirm or rule out the diagnosis.
If the CTA reveals no stenosis of the celiac artery and the superior mesenteric artery, again consider an alternative diagnosis.
However, if stenosis is found, this confirms the diagnosis of CMI. Here’s a clinical pearl to keep in mind!
Mesenteric artery occlusive disease, or MAOD for short, is a very common finding in elderly patients. However, not all patients with MAOD have CMI.
This is because the mesenteric artery supply is expansive with numerous collateral branches that perfuse the gut and in turn helps minimize symptoms.Alright, now that you’ve diagnosed CMI, the next step is to assess the severity of the occlusion on CTA.
Less than 70% occluded5:21–6:51
If the occlusion of either the celiac artery or the SMA is less than 70%, treat the patient with medical management, which includes antiplatelet therapy like aspirin, and statin therapy.
Next, encourage lifestyle modifications, such as tobacco cessation. Your patient should also undergo nutrition counseling to optimize lipid status, while addressing cachexia and malnutrition if present.
Next, treat underlying conditions such as hypertension, hyperlipidemia, and diabetes mellitus. Also, don’t forget to repeat the duplex ultrasound yearly for surveillance.
Your goal with these interventions is to delay progression of atherosclerotic disease within the abdominal vasculature and prevent the development of acute mesenteric ischemia.
Here’s a clinical pearl! Total parenteral nutrition, or TPN for short, delivers nutrients directly into the patient’s bloodstream.
Even though patients with CMI may have longstanding nutritional deficits, TPN is not recommended due to the risk of complications like bowel infarction and catheter-associated infections.
Instead, if needed, you should provide enteral feeding, or tube feeds, which delivers nutrients into the patient’s GI tract through the nose, mouth, or small intestine, and is much less prone to infections.Now, let’s go back to the occlusion severity.
Greater than 70% occluded6:51–7:25
If the occlusion of either the celiac artery or the SMA is 70% or greater, then obtain a surgical consultation for revascularization, which could involve widening the narrowing in vessels, stent placement, or bypass.
After surgery, start your patient on antiplatelet therapy like aspirin, as well as statin therapy. Again encourage lifestyle modifications, nutrition counseling, and treat underlying conditions.
Lastly, repeat a duplex ultrasound 6 months after revascularization, then yearly thereafter. Alright, as a quick recap… Chronic mesenteric ischemia, or CMI, refers to the long-term hypoperfusion of the mesenteric vasculature that results in inadequate oxygen supply to the intestines.
Review7:25–8:58
On the other hand, stable patients should first get a duplex ultrasound to assess for stenosis in the mesenteric artery.
If no stenosis is found, then consider an alternative diagnosis; but if the stenosis is present, you’ll want to get a CTA to confirm the diagnosis and assess the severity of the occlusion in the celiac artery or SMA.If the occlusion is less than 70%, proceed with medical management, primarily antiplatelet therapy and statins; encourage lifestyle modification, such as tobacco cessation and nutrition counseling; and treat the underlying conditions.
Also, don’t forget yearly surveillance with duplex ultrasound. On the flip side, if the stenosis is 70% or greater, proceed with surgical consultation for revascularization.
Next, start medical management with antiplatelet therapy and statin. Again, encourage lifestyle modifications; treat the underlying cause; and repeat duplex ultrasound in 6 months, then yearly thereafter.
- "Chronic mesenteric ischemia: Clinical practice guidelines from the Society for Vascular Surgery" J Vasc Surg (2021)
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