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Intestinal Ischemia
Introduction
A diminished blood flow to your small intestine or colon is referred to as 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.
Intestinal ischemia may develop suddenly (acute intestinal ischemia), often as a result of a blood clot blocking the flow of blood to or from the intestines, or it may develop gradually over time (chronic intestinal ischemia), due to a variety of causes.
Undetected and untreated, intestinal ischemia may be fatal. This condition, though uncommon, is serious and often requires immediate medical care. Depending on the cause of your intestinal ischemia, treatment options may include medications, surgery or a procedure to open your arteries.
Signs and symptoms
Although there are different types of intestinal ischemia, signs and symptoms are most often perceived as having a sudden (acute) or gradual (chronic) onset.
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.
Chronic intestinal ischemia, in which blood flow to the intestines is reduced over time, is characterized by:
- Abdominal cramps or fullness, beginning within 30 minutes after eating and lasting for 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.
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 heart 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.
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, your 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 for long, 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.
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 leading to your intestines, usually the superior mesenteric artery. 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 the 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 the intestines.
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 the pancreas (pancreatitis).
- Abdominal infection.
- Scarring of the 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 the abdomen.
- Hormone therapy, which can cause a blood clot.
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) may also 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.
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.
- If you're a smoker, quitting smoking.
Information obtained from National Institute of Health