Mesenteric ischemia: Causes, symptoms, diagnosis, treatment, and prevention

Mesenteric ischemia refers to poor blood supply to the intestines. The condition can affect the small intestines, large intestines, or both. Much like every other organ in your body, your digestive organs are also innervated by blood vessels to provide it with oxygenated blood. This is a necessity for the preservation of digestive function.

There exist two kinds of mesenteric ischemia: acute and chronic. Acute mesenteric ischemia occurs suddenly as a result of blockage of oxygen-rich blood and can lead to permanent damage to the intestines. Acute cases often require immediate medical care and can present with sudden abdominal pain and possibly bloody stool. Chronic mesenteric ischemia occurs gradually over time and can result from narrowing in one or more arteries supplying blood to the intestines (visceral arteries). Pain experienced in chronic cases may develop one to two hours after a meal, with this symptom often leading patients to skip meals entirely to avoid unbearable discomfort.

Prevalence of mesenteric ischemia

It is estimated that only about 0.1 percent of hospital admissions are due to acute mesenteric ischemia. However, this figure is expected to rise as the population ages. Approximately 10 to 15 percent of acute mesenteric ischemia cases and 0.006 percent of hospital admissions are believed to be the result of mesenteric venous thrombosis, a condition whereby a clot blocks blood flow to the mesenteric vein.

Cases of chronic mesenteric ischemia are relatively rare. According to a 1997 search through 20 years of literature, only 330 cases were identified. It is possibly due to lack of reporting, as this number is suspected to be much higher. Chronic mesenteric ischemia generally occurs in patients older than 60 years, with most studies suggesting an increased prevalence in females.

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What causes mesenteric ischemia?

Acute mesenteric ischemia causes include:

Acute mesenteric arterial embolism:

Occurs due to a blood clot that dislodges from the heart before traveling through the circulatory system, only to become lodged in blood vessels in the mesenteric system, most commonly in the superior mesenteric artery. This may be caused by:

• Mural thrombus after myocardial infarction
• Auricular thrombus associated with mitral stenosis and atrial fibrillation
• Septic emboli from valvular endocarditis
• Raptured or dislodged atheromatous plaque

Acute mesenteric arterial thrombosis:

Generally occurs in arterial branches and results in limited bowel ischemia. Thrombosis is the formation of a blood clot in a blood vessel, obstructing blood through the circulatory system.

• Atherosclerotic vascular disease (most common)
• Aortic aneurysm
• Aortic dissection
• Arteritis
• Decreased cardiac output from myocardial infarction or congestive heart failure
• Dehydration from any cause

Nonocclusive mesenteric ischemia:

Cases have been reported stating external compression of the celiac artery as a cause of mesenteric ischemia. This phenomenon has occurred in marathon runners who develop ischemic colitis after a marathon, with most instances resolving on their own with supportive treatment. Causes of nonocclusive mesenteric ischemia include

• Hypotension from CHF, MI, sepsis, aortic insufficiency, severe liver or renal disease, and recent major cardiac or abdominal surgery
• Vasopressors
• Ergotamines
• Cocaine use
• Digitalis

Mesenteric venous thrombosis:

Due to a blood clot forming in one or more of the major veins that drain blood from your intestine. While this condition is rare, it is increasingly recognized as a cause of mesenteric ischemia. Causes leading to mesenteric venous thrombosis include:

• Hypercoagulability
• Tumors
• Infections
• Venous congestion
• Venous trauma
• Increased intra-abdominal pressure
• Pancreatitis
• Decompression syndrome

Chronic mesenteric ischemia causes include:

Atherosclerosis:

A disease where plaque builds up inside the arteries, resulting in the reduced flow of oxygenated blood sent to various parts of the body, possibly involving the mesenteric arteries. Factors that predispose one to atherosclerosis include:

• Smoking
• Hypertension
• Diabetes
• Hypercholesterolemia

Symptoms and complications of mesenteric ischemia

Symptoms of acute mesenteric ischemia include:

• Sudden severe stomach pain
• Nausea and vomiting (sometimes)

Symptoms of chronic mesenteric ischemia include:

• Severe stomach pain up to an hour after eating
• Pain lasting for as long as two hours
• Pain that recurs with every meal
• Nausea and vomiting
• Diarrhea
• Flatulence
• Weight loss
• Feelings of hunger

How to diagnose mesenteric ischemia?

The diagnosis of mesenteric ischemia will begin with a detailed description of presenting symptoms, a medical history, and physical exam. Blood tests may also be taken to help assess your current health status as well as rule out other potential causes for your symptoms.

Imaging tests that help evaluate blood flow may also be done and can help rule out other causes of abdominal pain. These tests include:

• Doppler ultrasound: A high-frequency test using sound waves to help create images of internal structures. It can also help to evaluate blood flow.
• CT scan/CT angiography: A highly detailed imaging test that allows for the better assessment abdominal anatomy. This may be a useful test to look for blood flow to various digestive organs.
• Magnetic resonance angiography (MRA): Using magnetic fields and radio waves to produce highly detailed images of blood vessels.
• Mesenteric angiogram: A standard test for evaluating blood flow and identifying narrowing and blockages in the blood vessel. It is performed by guiding a thin, flexible tube (catheter) through an artery and then injecting a dye to make the blood flow more visible on an x-ray. This test can also be used to perform various treatment options as well, including performing balloon angioplasty or stent placement.

How to treat mesenteric ischemia?

Acute mesenteric ischemia treatment may include:

• Emergency medical care in the hospital: As severe intestinal damage can occur rapidly
• Narcotic pain medication: To relieve severe pain
• Thrombolytic therapy: Used to break apart a clot when found early enough and often given during an angiogram
• Surgery: An option when evidence of intestinal damage has already occurred, or too little time is available for thrombolytic therapy to be effective. Surgery is done to remove the clot directly and restore blood flow to the intestinal arteries. If significant portions of the intestine are damaged, removing them may be the only option.

Chronic mesenteric ischemia treatment:

• Interventional procedures: Includes angioplasty (with or without stenting), mesenteric artery bypass, or mesenteric endarterectomy

Diet for mesenteric ischemia

In chronic cases of mesenteric ischemia, it is recommended to adhere to a low-fat diet, similar to patients with cardiac disease. Meals should be kept small and eaten multiple times a day to help avoid severe stomach pain after eating. Additionally, regular exercise is also encouraged.

Preventing mesenteric ischemia

• Quit smoking: Not only does it harm blood vessels, but smoking is also known for increasing plaque buildup in the arteries, making it a significant risk factor for the development of atherosclerosis
• Maintain healthy blood pressure and cholesterol levels: Having uncontrolled blood pressure and cholesterol levels can cause your arteries to become stiff and narrow over time, reducing blood flow. Fortunately, lifestyle changes can reverse this – simply exercise regularly, eat a diet rich in fruits, vegetables, and whole grains, and eliminate alcohol from your diet. If this is unattainable for you, seek help from your local doctor who can prescribe medication to help reduce blood pressure and cholesterol levels.
• Exercise regularly: By incorporating more physical activity into your daily routine, you can help improve cholesterol levels. lower blood pressure, boost circulation, and even reduce stress.
• Control diabetes: Having uncontrolled diabetes can contribute to developing blockages in the arteries and potentially lead to coronary artery disease and a heart attack. Healthy diets and exercise can help control diabetes, but it is also important to be aware of blood glucose levels during meal time.

Prognosis of mesenteric ischemia

Despite improved overall survival rates of acute mesenteric ischemia over the last couple of years, these rates still remain relatively high. Over the last 15 years, the all-cause mortality from acute mesenteric ischemia averaged at 71 percent, while hovering in a range between 59 and 93 percent. Mortality may be as high as 90 percent once bowel infarction has occurred. Even with adequate treatment measures, as many as 50 to 80 percent of patients will die from the acute form of this condition. Those who survive still have a high chance of re-thrombosis and decreased quality of life as the removal of the intestine will require them to consume their meals through total parenteral nutrition – nourishment that is delivered to the body through a vein in the limb (in cases of short-gut syndrome).

While cases of chronic mesenteric ischemia are a relatively rare cause of death, it can occur. Often times, it could be related to the mesenteric ischemia itself, cardiac conditions, or other non-related causes such as cancer. Patients predisposed to thrombosis or embolism development may result in their death as well. Due to their fear of stomach pain after eating meals, chronic mesenteric ischemia patients may have prolonged hospital visits due to chronically malnourished states.

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