Overview

Mesenteric ischemia is a condition that occurs when the blood flow to the intestine is decreased or blocked which can result in permanent damage to the intestines. When blood can’t flow properly, the affected organs and tissues don’t get enough oxygen and can’t work as they should. If the blockage is severe, the organs and tissues might start to die. It’s more common in older people, especially those with heart problems or blood clotting issues. Mesenteric ischemia can be life threatening and the outlook depends on how early the condition is diagnosed and treated; early diagnosis, intervention and timely treatment can significantly improve outcomes. 

Types of mesenteric ischemia

There are two types of mesenteric ischemia:

Acute mesenteric ischemia

Acute mesenteric ischemia (AMI) occurs when the blood supply to the intestine is suddenly cut off, causing cell damage and tissue death in the intestines. If not treated quickly, it can often lead to the death¹. 

Symptoms

• Sudden, intense abdominal pain
• Urgent need to have a bowel movement
• Fever
• Nausea and vomiting
• Unexplained abdominal swelling
• Gastrointestinal bleeding²

What are the causes of AMI

• Superior mesenteric artery (SMA) embolism

A sudden blockage in the SMA caused by a blood clot that travels from another part of the body.

• Atherosclerotic SMA occlusion (thrombosis)

Gradual blockage of the SMA due to plaque buildup (atherosclerosis) that forms a clot.

• Non-occlusive mesenteric ischemia (NOMI)

Occurs when there’s no major blockage in the mesenteric arteries but is caused by other issues like low blood flow from heart problems or blood vessel constriction.

• Venous mesenteric ischemia

Caused by a blood clot in the veins of the intestines, known as mesenteric venous thrombosis⁴

Common risk factors of acute mesenteric ischemia

• Atrial fibrillation 

An irregular and often fast heart rhythm

• Congestive heart failure 

The heart doesn't pump blood effectively

• Recent vascular surgery

Early diagnosis of acute mesenteric ischemia (AMI)

Early diagnosis is crucial. The typical presentation includes severe abdominal pain with findings on the physical exam or radiographic imaging. If the exam shows signs of peritonitis (abdominal lining inflammation), it usually means the intestines are severely damaged. 

Some patients may present with a combination of abdominal pain, fever, and positive stool tests for blood. Others, particularly if diagnosed late, might show signs of septic shock. Peritonitis signs can be subtle, so it’s important to stay vigilant for these symptoms as they often indicate serious intestinal damage.⁵

Computed tomography angiography (CTA) should be performed quickly in any patient suspected of having AMI. Multidetector CTA has now become the preferred diagnostic method, replacing traditional angiography.¹ Delaying the diagnosis is the main reason for the high mortality rates, which range from 30% to 70%. Every 6-hour delay in diagnosis, specifically in performing a CTA, doubles the risk of death. 

Chronic mesenteric ischemia

Chronic mesenteric ischemia is almost always caused by atherosclerosis (a buildup of fat in arteries making them narrow) in the main arteries that supply blood to the intestines.

Symptoms

• Crampy abdominal pain after eating, often leading to "food fear" where patients avoid eating to prevent discomfort
• Digestive problems: 50% to 70% experience gastrointestinal motility disturbances
• Significant weight loss
• An abnormal sound in the abdomen
• Signs of atherosclerosis, the plaque buildup in other parts of the body
• Patients often have several cardiovascular risk factors²

Causes of CMI

The main cause of CMI is atherosclerosis, where arteries that supply the intestines become narrowed. Less often, it can be caused by inflammation of the blood vessels. Atherosclerotic CMI mostly affects older people (around 69 years old), with high rates in smokers and patients with high blood pressure or heart disease. The intestines are fed by three main arteries: the celiac artery (CA), superior mesenteric artery (SMA), and inferior mesenteric artery (IMA). They have a backup system of smaller vessels that can help if one artery is blocked. The narrowing of the celiac artery (CA) and superior mesenteric artery without any symptoms is common, especially as people get older. About 3% of people under 65 and 18% of those over 65 have this issue. Any issue with the three main arteries of the intestine can lead to CMI. 

Multi-vessel stenosis 

CMI often involves narrowing of several arteries, but even a blockage in just one can cause problems. Treating a single blocked artery can often relieve symptoms.

Median arcuate ligament syndrome (MALS)

A common cause of CA narrowing is MALS, where a ligament compresses the CA. This compression changes with breathing: it can get worse during expiration and better during inspiration. Typically affects younger people (ages 37–54), especially women, with fewer links to smoking or heart disease.

Chronic non-occlusive ischemia (NOMI)

About 13–16% of CMI cases are NOMI, where symptoms appear without clear artery narrowing. It might be caused by heart or lung issues, small artery blockages, or nervous system problems. Treatment focuses on these underlying issues, but managing NOMI can be challenging because its causes are not fully known.³

Common risk factors of chronic mesenteric ischemia

• Type 2 diabetes
• High cholesterol levels
• High blood pressure
• Cardiovascular disease
• Smoking
• Obesity
• Older age

Early diagnosis of chronic mesenteric ischemia

To diagnose CMI, doctors look for classic symptoms and significant narrowing of the mesenteric arteries. The typical symptoms include weight loss, pain after eating and fear of eating. However, this set of symptoms might not always be present, and patients can also have vague symptoms like abdominal discomfort, nausea, vomiting, diarrhoea, or constipation. The abdominal pain is often felt in the middle of the abdomen and may be crampy or dull. It usually starts within 30 minutes after eating and can last up to 6 hours. Certain foods can make the pain worse, so patients often change their eating habits to avoid these triggers.⁶

Computed tomography angiography (CTA) is the preferred imaging method for patients with moderate to high suspicion of CMI.³

Prognosis and treatment approaches for AMI

Once acute mesenteric ischemia (AMI) is diagnosed, treatment usually involves:

• Fluid resuscitation is essential to restore blood flow to the intestines. Electrolyte imbalances should be corrected, and nasogastric decompression should be started
• Broad-spectrum antibiotics are usually administered in patients with AMI due to the high risk of infection. The early use of antibiotics helps prevent septic complications, as intestinal ischemia can quickly compromise the mucosal barrier
• Laparoscopy or laparotomy is recommended for patients with clear signs of peritonitis. Surgery should be done without any delay to:
  • Restore blood flow
  • Remove non-viable bowel
  • Preserve healthy tissue¹ 

Prognosis and treatment approaches for CMI

• Treatment for CMI should be decided by the patient and provider, considering the risks, benefits, and the patient's care goals
• Endovascular revascularization is recommended as the first treatment option for patients with CMI if appropriate
• Open surgical revascularization are reserved for patients with CMI whose lesions are unsuitable for endovascular therapy, for cases where endovascular treatment has failed, or for select younger, healthier patients who may benefit from the long-term advantages despite the higher surgical risks⁶

What are the outcomes of acute mesenteric ischemia

• AMI is a serious condition with high death rates that haven't improved much over time. Open surgeries for AMI usually involve fewer bowel resections⁷
• Most AMI patients need lifelong anticoagulation or antiplatelet therapy to prevent relapse
• Regular imaging is crucial to monitor for restenosis, with recommended follow-ups at 1, 6, and 12 months, or annually
• Long-term care should focus on managing underlying conditions and lifestyle changes to minimise relapse risk¹

What are the outcomes of chronic mesenteric ischemia

• Regular follow-up after CMI treatment can help detect symptomatic restenosis, but the benefit of treating asymptomatic restenosis is unclear. Antiplatelet therapy is advised after revascularization, considered for 3–12 months
• Open surgical revascularization has a higher risk of in-hospital complications compared to endovascular revascularization but tends to have lower long-term recurrence rates. Immediate symptom relief is high for both methods, with surgery offering better long-term results
• Endovascular revascularization has a lower in-hospital mortality rate, shorter hospital stays, and lower costs compared to surgery³
• It is important to balance the timing of the intervention to avoid worsening the condition into acute mesenteric ischemia

Summary

Mesenteric ischemia is a rare health condition with a high mortality rate. The prognosis of mesenteric ischemia depends on the correct diagnosis, treatment and outcomes of the condition. AMI is a critical medical emergency requiring urgent treatment while CMI develops gradually. Prompt diagnosis and treatment are crucial, as delay can lead to greater risks. As a result, healthcare providers may opt for quicker surgical intervention. When identified early, mesenteric ischemia is treatable and can often be reversed.