Intestinal ischemia

Definition

Like your other organs, your digestive system needs a constant supply of oxygen-rich blood to function properly. A diminished blood flow to your small intestine or colon is called intestinal ischemia (is-KE-me-uh).

Intestinal ischemia can cause pain and make it difficult for your intestines to do their job. In severe cases, loss of blood flow to the intestines can lead to damaged or dead intestinal tissue, not unlike what happens to the heart during a heart attack. And like a heart attack, intestinal ischemia can be fatal.

But you can receive effective treatments for intestinal ischemia. The most critical factor in effectively treating intestinal ischemia is recognizing the early symptoms and getting medical help right away.

Symptoms

Intestinal ischemia may develop suddenly (acute intestinal ischemia), often as a result of a blood clot blocking the flow of blood to or from your intestines, or it may develop gradually over time (chronic intestinal ischemia) due to a variety of causes.

Symptoms of acute intestinal ischemia
Signs and symptoms of acute intestinal ischemia typically include:

• Sudden abdominal pain that may range from mild to severe
• An urgent need to move your bowels
• Frequent, forceful bowel movements
• Abdominal tenderness or distention
• Blood in your stool
• Nausea, vomiting
• Fever

Symptoms of chronic intestinal ischemia
Chronic intestinal ischemia, in which blood flow to your intestines is reduced over time, is characterized by:

• Abdominal cramps or fullness, beginning within 30 minutes after eating and lasting one to three hours
• Abdominal pain that gets progressively worse over weeks or months
• Fear of eating because of subsequent pain
• Unintended weight loss
• Diarrhea
• Nausea, vomiting
• Bloating

Chronic intestinal ischemia may progress to an acute episode. If this happens, you might experience severe abdominal pain after weeks or months of bouts of intermittent pain after eating.

When to see a doctor
Delaying treatment for intestinal ischemia may make treatment more difficult. Seek emergency care if you have sudden, persistent abdominal pain.

In addition, see your doctor as soon as possible if you have one or more of these signs or symptoms:

• Blood in your stool
• Chronic abdominal pain after eating, especially if you're also losing weight

Causes

The aorta is the large artery that supplies your body's vessels with oxygen-rich blood pumped by your heart. The portion of the aorta extending below your diaphragm into your abdomen is the abdominal aorta. Three arteries branching off the abdominal aorta supply almost all of the blood to your digestive tract. These arteries are the:

• Celiac artery
• Superior mesenteric artery
• Inferior mesenteric artery

When the flow of blood through these arteries or their adjacent draining veins is altered, whether the change is acute or chronic, intestinal ischemia may result.

Like other arteries in your body, any or all of the arteries that serve your digestive tract may be affected by an accumulation of cholesterol particles, scar tissue, calcium and other cellular debris (atherosclerosis), which narrows those arteries and restricts the amount of blood moving through them. Atherosclerotic buildup can progressively reduce blood flow to your small intestine or large intestine or both. Chronic intestinal ischemia is often the result of atherosclerotic buildup.

Most of the time, acute intestinal ischemia is due to a blood clot that forms in your heart and then travels to one of your intestinal arteries. Other times a blood clot may develop in a vein leading away from the intestines, diminishing the outflow of deoxygenated blood. Sometimes intestinal ischemia occurs because a portion of your intestine becomes trapped due to a hernia (strangulated hernia) or due to adhesions from a previous abdominal surgery. Other times it occurs because of heart failure or low blood pressure.

Whatever the cause, diminished blood flow within your digestive tract leaves cells with insufficient oxygen. Under these conditions, cells become weak and die. As more and more cells are damaged, inflammation and ulcers develop. This leads to an inability to absorb food and nutrients, resulting in bloody diarrhea. If damage is severe enough, infection and gangrene may result. If untreated, intestinal ischemia can be fatal.

Intestinal ischemia is often divided into several categories:

Colon ischemia (ischemic colitis)
Disrupted blood flow to the colon is the most common type of intestinal ischemia. It most often occurs in older adults, although it may develop in younger people.

Signs and symptoms of colon ischemia are generally milder than with other forms of intestinal ischemia, and severe complications are uncommon. For most people, colon ischemia appears as a sudden onset of mild, crampy pain on the left side of the abdomen. What causes diminished blood flow to the colon isn't always clear, but a number of conditions can make you more vulnerable to colon ischemia:

• Atherosclerosis
• Dangerously low blood pressure (hypotension) associated with congestive heart failure, major surgery, trauma, shock or life-threatening infection in your bloodstream (sepsis)
• A blood clot in an artery supplying the colon
• Bowel obstruction caused by a strangulated hernia, scar tissue or a tumor
• Heart, blood vessel, intestinal or gynecologic operations
• Other medical disorders that affect your blood, such as inflammation of your blood vessels (vasculitis), lupus or sickle cell anemia
• Some medications, especially those that constrict blood vessels, such as some heart, migraine or hormone medications
• Cocaine or methamphetamine use
• Vigorous exercise, such as long-distance running

Acute mesenteric ischemia
This type of intestinal ischemia usually affects the small intestine. It has an abrupt onset and may be due to:

• A blood clot that dislodges from your heart and travels through your bloodstream (emboli) to block an artery, usually the superior mesenteric artery, leading to your intestines. This is the most common cause of acute mesenteric artery ischemia and can be precipitated by congestive heart failure, an irregular heartbeat (arrhythmia) or a heart attack.
• A blood clot that develops within one of the main intestinal arteries (thrombosis) and blocks blood flow, often as a result of atherosclerosis. This type of acute ischemic episode tends to occur in people with chronic intestinal ischemia.
• Impaired blood flow resulting from low blood pressure due to shock or heart failure. This is more common in people who are critically ill and who have some degree of atherosclerosis. You may hear this type of acute mesenteric ischemia referred to as nonocclusive ischemia, which means that it's not due to a vascular obstruction.
• Aortic dissection, a partial tear in the main artery from your heart (aorta), which causes a separation of the layers of the aortic wall and bleeding into and along the wall of the aorta, thus reducing blood flow to your intestines.

Chronic mesenteric ischemia
Chronic mesenteric ischemia, also known as intestinal angina, results from atherosclerosis. The disease process is generally so gradual that at least two of the three major arteries supplying your intestines become severely narrowed or completely obstructed before you experience symptoms. A potentially dangerous complication of chronic mesenteric ischemia is the development of a blood clot within a diseased artery, causing acute mesenteric ischemia.

Ischemia due to mesenteric venous thrombosis
Occasionally, a blood clot will develop in a vein draining deoxygenated blood away from your intestines. Blockage of the vein causes intestinal congestion, swelling and bleeding. A blood clot in a mesenteric vein may result from:

• Acute or chronic inflammation of your pancreas (pancreatitis)
• Abdominal infection
• Scarring of your liver (cirrhosis)
• Cancers of the digestive system
• Bowel diseases, such as ulcerative colitis, Crohn's disease or diverticulitis
• Disorders that make your blood more prone to clotting (hypercoagulation disorders), such as an inherited protein deficiency
• Trauma to your abdomen
• Hormone therapy, which can cause a blood clot

Mesenteric ischemia

Mesenteric ischemia

The arteries that supply almost all of the blood needed by your digestive tract are the celiac artery, the superior mesenteric artery and the inferior mesenteric artery. Any or all of these arteries may be affected by atherosclerosis or blood clots.

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Risk factors

Many of the risk factors for intestinal ischemia are those associated with atherosclerosis and clogging of the mesenteric arteries. These factors include:

• Age (older than 50)
• High blood pressure (hypertension)
• Diabetes
• Elevated levels of blood lipids or fats
• Smoking

Your risk is also higher if you have a history of atherosclerosis that affects blood flow in other areas of your body, such as your heart (coronary artery disease), legs (peripheral vascular disease) or the arteries serving your brain (cerebrovascular disease).

Other factors that can increase your risk of intestinal ischemia include low blood pressure, congestive heart failure, an irregular heartbeat, a blood-clotting disorder, a hernia and previous abdominal surgery.

Risk factors for ischemia due to mesenteric venous thrombosis include extended bed rest, obesity, certain types of cancer, birth control pills, smoking, and a history of high blood pressure or heart disease.

Complications

Sometimes blood flow to your digestive tract is completely and suddenly cut off due to a blood clot that travels to the area, often from your heart. The same is true if a clot develops in one of the three arteries that serve your digestive tract where there's already some atherosclerotic buildup. It's also possible that blood clots or atherosclerotic buildup may be dislodged from a larger artery or the aorta by a catheter during a diagnostic procedure, which can cause a blockage of smaller arteries downstream. These are medical emergencies.

Blockage of the blood flow to your intestine may result in death of intestinal tissue (infarction or necrosis). If this life-threatening situation occurs, you'll need surgery to clear the blockage and to remove the portion of the intestine that has died. In order to limit the amount of intestinal tissue removed, your surgeon may plan to operate again (second-look operation) to be sure that remaining bowel tissue is healthy.

After removing damaged intestinal tissue, your surgeon may be able to connect the healthy ends together. If that's not possible, your surgeon may need to perform a procedure called an ostomy. In this procedure, the surgeon creates an opening in your abdomen to pull a section of your intestine to the surface. A bag is then attached to this opening, and your waste is expelled into the bag.

Blockage of blood flow to the colon can lead to scarring and narrowing of your colon, which may require surgical treatment.

Preparing for your appointment

Go the emergency room if you have severe or persistent abdominal pain. You may be referred for immediate surgery to diagnose and treat your condition.

If your abdominal pain is moderate and predictable — for example, it always begins soon after eating — call your doctor for the first possible appointment. When you call to set up an appointment, you may be referred immediately to a specialist, such as a gastroenterologist or vascular surgeon.

Because appointments can be brief, and because there's often a lot of ground to cover, it's a good idea to be well prepared for your appointment. Here's some information to help you get ready for your appointment, and what to expect from your doctor.

What you can do

• Be aware of any pre-appointment restrictions. At the time you make the appointment, be sure to ask if there's anything you need to do in advance, such as restrict your diet. It's likely that your doctor will ask you not to eat after midnight on the night before your appointment.
• Write down any symptoms you're experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
• Write down other medical conditions or procedures you've had, including problems you were treated for in the past, such as a blood clot, and long-term health problems for which you're still being treated.
• Make a list of all medications, as well as any vitamins or supplements, that you're taking. If you take birth control pills, write down the drug's name.
• Take a family member or friend along, if possible. Sometimes it can be difficult to soak up all the information provided to you during an appointment. Someone who accompanies you may remember something that you missed or forgot.
• Write down questions to ask your doctor.

Your time with your doctor is limited, so preparing a list of questions ahead of time will help you make the most of your time together. List your questions from most important to least important in case time runs out.

For intestinal ischemia, some basic questions to ask your doctor include:

• What is likely causing my symptoms or condition?
• Other than the most likely cause, what are possible causes for my symptoms or condition?
• Do you think my condition is temporary or chronic?
• What kinds of tests do I need?
• What treatments do I need right now?
• If I need surgery, what will my recovery be like? How long will I need to be in the hospital?
• How will my diet and lifestyle change after I have surgery?
• What follow-up care and treatments will I need?
• Should I see a specialist? What will that cost, and will my insurance cover seeing a specialist?
• Is there a generic alternative to the medicine you're prescribing me?
• Are there any brochures or other printed material that I can take home with me? What Web sites do you recommend visiting?

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment at any time that you don't understand something.

What to expect from your doctor
Your doctor is likely to ask you a number of questions. Being ready to answer them may reserve time to go over any points you want to spend more time on. Your doctor may ask:

• When did you first begin experiencing symptoms?
• Have your symptoms stayed the same or gotten worse over time?
• Have your symptoms been continuous, or occasional?
• How severe are your symptoms?
• If your symptoms appear after eating, have they caused you to fear or avoid meals?
• How soon after eating do your symptoms begin?
• Do you tolerate small meals better than large ones?
• Are liquids easier to tolerate than solids?
• What, if anything, seems to improve your symptoms?
• What, if anything, appears to worsen your symptoms?
• Do you or did you smoke? How much?

Tests and diagnosis

If your doctor suspects intestinal ischemia, he or she may want to conduct a thorough medical evaluation because signs and symptoms of intestinal ischemia can be similar to those of other disorders, such as ulcers, as well as stomach, pancreatic or colon cancer.

You may undergo several diagnostic tests, based on your signs and symptoms, including:

• X-ray. This test uses radiation to allow your doctor to view your internal organs on film.
• Ultrasound. Ultrasonography uses sound waves to generate images of internal organs on a monitor. A special ultrasound (Doppler) of the celiac, superior mesenteric and inferior mesenteric arteries can help your doctor determine if there's decreased blood flow, which indicates a likelihood of chronic mesenteric ischemia.
• Endoscopy. This technique involves inserting a lighted, flexible tube with a camera on its tip (endoscope) through your mouth and into your esophagus, stomach and duodenum. You're usually sedated for this procedure.
• Colonoscopy and flexible sigmoidoscopy. A thin, flexible tube (catheter) is inserted into your rectum. A tiny camera on the end captures images of your colon. Colonoscopy allows your doctor to view your entire colon, while sigmoidoscopy allows your doctor to visualize the last 2 feet of your large intestine.
• Angiography. This type of testing involves guiding a catheter through an artery in your groin up into the aorta and injecting a dye (radiographic contrast medium). The dye allows better visualization of your intestinal arteries. Although invasive, angiography has traditionally been considered the gold standard in evaluating mesenteric ischemia. Its advantage is that it allows for simultaneous removal of a blood clot through the catheter or administration of medications to improve intestinal blood flow. But other newer, less invasive technologies, such as computerized tomography (CT) scanning and magnetic resonance angiography (MRA), are becoming useful in diagnosis.
• Computerized tomography (CT). This X-ray technique allows your doctor to see thin sections of your body and to view internal organs with more clarity and detail than with a conventional X-ray. CT may also provide images of portions of the intestinal arteries. A new technique called CT angiography can provide better images of the intestinal arteries, though it's not widely used yet.
• Magnetic resonance angiography (MRA). This newer, noninvasive technology uses magnetic fields and radio waves to provide clear images of the circulation to your bowel and may be performed before angiography. This test may help guide further testing or treatment.
• Exploratory surgery. In some cases, especially when acute mesenteric ischemia is suspected, you may need exploratory surgery. Acute mesenteric ischemia is a medical emergency and needs to be diagnosed and treated quickly and accurately. Opening up the abdomen allows for diagnosis and treatment within one procedure. The choice of testing depends on your doctor's judgment of your condition and the likelihood of the diagnosis.

Arriving at a diagnosis
In general, the diagnoses of various types of intestinal ischemia are as follows:

• Colon ischemia. This type is generally diagnosed by using colonoscopy or sigmoidoscopy. Rarely, colon ischemia can be due to colon cancer. Once the colon ischemia has improved, a colonoscopy is usually performed to adequately look at the colon.
• Acute mesenteric ischemia. This type is diagnosed by considering your symptoms and the results of blood tests, abdominal X-rays, ultrasound, angiography or exploratory surgery.
• Chronic mesenteric ischemia. Diagnosis of this type is usually made based on clinical symptoms, the lack of other existing gastrointestinal disorders and the results of an angiogram.
• Ischemia due to mesenteric venous thrombosis. Doctors can usually diagnose this type using CT scanning. Evaluation for blood-clotting problems also may be done.

Treatments and drugs

Treatment of intestinal ischemia involves restoring a sufficient blood supply to your digestive tract. Options vary depending on the cause and severity of your condition:

• Colon ischemia. Antibiotics are often used to treat or prevent infections. Your doctors also will treat any underlying medical condition, such as congestive heart failure or an irregular heartbeat. You'll need to stop any medications that constrict your blood vessels, such as migraine drugs, hormone medications and some heart drugs.

  If your colon has been damaged, you may need surgery to remove the dead (infarcted) tissue. Or, you may need surgery to bypass a blockage in one of your intestinal arteries. The procedure is similar to what's done when blocked coronary arteries of the heart are bypassed to redirect blood flow around a blockage. Because colon cancer is one of the causes of colonic ischemia, your doctor will likely consider a full colonoscopy after your symptoms improve to get a better look at your colon.

• Acute mesenteric artery ischemia. Surgery is often necessary to remove a blood clot, bypass an artery blockage, or to repair or remove a damaged section of intestine. Treatment also may include medications to prevent clots from forming, dissolve clots or dilate blood vessels.

  If angiography is done to diagnose the problem, the radiologist may simultaneously be able to remove a blood clot, or open up the narrowed artery with angioplasty. Angioplasty involves using a balloon inflated at the end of a catheter to compress the fatty deposits and stretch the artery, making a wider path for the blood to flow. A spring-like metallic coil (stent) also may be placed in your artery to help keep it open.

• Chronic mesenteric artery ischemia. Treatment involves restoring blood flow to your intestine. Your surgeon can bypass the blocked arteries or widen narrowed arteries with angioplasty therapy or stenting.
• Ischemia due to mesenteric venous thrombosis. If your intestines show no signs of damage, you'll likely need to take anticoagulant medication for about three to six months. Anticoagulants help prevent clots from forming. If portions of your bowel show signs of damage, however, you'll need surgery to remove the damaged section. After surgery, you may need to take an anticoagulant for a short time.

Prevention

Intestinal ischemia is often a warning sign of more widespread atherosclerosis. If you have health conditions such as diabetes, high blood pressure, or elevated blood cholesterol or triglycerides, any of which could result in or aggravate atherosclerosis, work closely with your doctor to manage and control these conditions.

The preventive steps that you and your doctor discuss may include:

• Making changes in your diet
• Becoming more physically active
• Losing weight
• Taking medications
• Changing or avoiding medications that may have contributed to your symptoms
• If you're a smoker, quitting smoking

Taking steps to prevent atherosclerosis will reduce your risk of intestinal ischemia as well as other serious disorders, such as heart attack and stroke.