Intestinal Ischemia - Causes, Types, Symptoms, Diagnosis, and Treatment

Introduction:

Intestinal ischemia is when blood flow to a particular part of the intestine stops due to blocked blood vessels (mostly an artery). It may lead to various other conditions, such as necrosis and death of that part of the intestine. Ischemia can affect any part of the intestines, whether the small intestine or the large intestine. It is a serious condition that may lead to pain and impairment in the intestine's functioning, which further affects digestion and absorption of nutrients. The condition must be diagnosed early to prevent more complications and get proper treatment.

What Are the Causes of Intestinal Ischemia?

Intestinal ischemia happens when the blood flow by the major arteries of the intestine is blocked or reduced. The causes of this blockage can be many diseases and factors, such as clotting in the arteries and narrowing of the arterial wall due to deposits such as cholesterol. Ischemia can also occur due to blockage in the veins, but it is rare compared to arteries.

The intestinal ischemia can be divided into two parts:

1. Acute Mesenteric Ischemia: Ischemia affecting the small intestine due to factors such as:

• Dislodgement of a Blood Clot From the Heart: A blood clot, known as an embolus, travels in the bloodstream from the heart to the intestinal vessels and blocks them. It usually occurs in the superior mesenteric artery, which is known to supply oxygen-rich blood to the intestine. It is the most common type of ischemia, which may occur in congestive heart failure, heart attack, and arrhythmia.

• Low Blood Pressure Leads to Decreased Blood Flow to the Intestine: This can happen due to heart failure, shock, chronic kidney failure, or due to certain medications. This is more common in people who are chronically ill or have atherosclerosis. This type of acute mesenteric ischemia is called non-occlusive ischemia as it is not caused due to blockage in the artery.

• Blockage in One of the Major Arteries of the Intestine: This occurs due to fatty depositions in the arterial wall. This type is seen in people with chronic intestinal ischemia.

2. Chronic Mesenteric Ischemia: This condition is also called intestinal angina, which results from forming fatty deposits in the artery's walls. The disease is gradual and does not require treatment until two major arteries supplying the intestine are severely blocked or completely obstructed. The most dangerous complication of chronic ischemia is the formation of a blood clot in the narrowed artery leading toacute mesenteric ischemia.

3. Ischemic Colitis (Colon Ischemia): It is the most common type of intestinal ischemia affecting the large intestine. It generally occurs when blood flow to the colon is reduced or blocked. Some of the conditions which may lead to this ischemia are:

• A blood clot in the arterial supplies to the colon.

• Low blood pressure may be associated with heart failure, major surgery, or trauma.

• Twisting of the intestines or trapping of the intestinal contents in a hernia.

• Obstruction due to a tumor or scar tissue leads to excessive bowel enlargement.

• Infections of the blood, such as lupus, vasculitis (inflammation of the vessels), and sickle cell anemia.

• Medications such as those used for migraine or heart diseases may constrict the blood vessels.

• Vigorous exercises such as long-distance running may lead to colonic ischemia.

4. Ischemia Due to Blockage in the Veins: When the blood clot develops in the vein, the blood cannot leave the intestine leading to bleeding and swelling. This condition is known as mesenteric venous thrombosis. The causes behind this condition are:

• Abdominal infections.

• Acute or chronic pancreatitis.

• Disorders leading to hypercoagulation of blood.

• Malignancies of the abdominal organs. Estrogen medications increase the risk of coagulation.

What Are the Symptoms of Intestinal Ischemia?

The symptoms of acute ischemia develop suddenly, and chronic signs and symptoms are gradual and may vary from person to person. However, there are some general symptoms seen in the affected cases:

• Symptoms of Acute Intestinal Ischemia:

1. An urge to have a bowel movement.

2. Sudden abdominal pain can be mild, moderate, or severe.

3. Presence of blood in the stools.

4. Abdominal tenderness or distension was noticed.

5. Some older adults may witness mental confusion.

• Symptoms of Chronic Intestinal Ischemia:

1. Fullness or abdominal cramps are usually felt after half an hour of eating, which may last about one to three hours.

2. Fear of eating as there is pain after eating.

3. Diarrhea, nausea, and bloating of the abdomen.

4. Uncontrollable weight loss.

5. Progressive abdominal pain, which gets worse over weeks.

How to Diagnose Intestinal Ischemia?

The diagnostic tests which may lead to the identification of intestinal ischemia are:

• Blood Tests: There are no specific blood markers to identify intestinal ischemia, but an increase in the number of white blood cells indicates a chance of infection.

• Endoscope or Colonoscope: Insertion of a small tube with a camera from the mouth (endoscopy) or the colon (colonoscopy) to locate the site of ischemia.

• Dye Which Traces Path of Blood Flow Through the Arteries: This test is known as angiography, in which a thin catheter is inserted from the groin or arm into the artery and then passed to the aorta. A dye is then injected through this artery which directly reaches the intestinal arteries and helps to locate the site of ischemia or blockage. This technique helps to remove a blockage from the arteries.

• Exploratory Surgery: In some cases where it is difficult to locate the ischemia, surgery is performed where the affected tissue is located and removed simultaneously.

What Is the Treatment for Intestinal Ischemia?

Treating intestinal ischemia characterizes restoring the blood supply to the digestive tract. Different treatment options depend on the cause and severity of the ischemia.

• Acute Mesenteric Ischemia: In cases of suddenly occurring ischemia, surgery might be needed to remove blood coagulation or to bypass the artery blockage. The infected and damaged section of the intestine should also be removed. Medications such as anticoagulants can also be prescribed to avoid clot formation, and antibiotics to treat the infection.

• Chronic Mesenteric Ischemia: Restoration of the blood flow is done by removing the clots or by bypassing the blocked arteries. The process of angioplasty can widen the narrowed arteries.

• Colonic Ischemia: This ischemia generally heals itself and may require only antibiotic treatment to cure the infections. If there is any underlying disease causing ischemia, it should be treated.

• Ischemia Because of Mesenteric Venous Thrombosis: Anticoagulants can be prescribed for about three to six months if the intestine does not show any damage. However, anticoagulants are prescribed for a lifetime in case of any blood-clotting disorder.

What Are the Risk Factors That Can Lead To Intestinal Ischemia?

• Fat Deposition in the Arteries: If a person has atherosclerosis in any other part of the body, such as the coronary artery, legs, or the arteries which serve the brain, there is a risk of developing a blockage in intestinal arteries too.

• Smoking: Tobacco and cigarettes always increase the risk of intestinal ischemia.

• Age: People older than 50 are more prone to developing intestinal ischemia.

• Medications: Some medicines, such as birth control pills or migraine medications, may increase the chances of intestinal ischemia.

• Blood-Clotting Disorders: Conditions that lead to blood coagulation in the vessels increase the risk of intestinal ischemia.

Conclusion:

Intestinal ischemia is a condition caused due to insufficient blood supply to any part of either the small or the large intestine. It can be due to any clot formation in the arteries or fat accumulation leading to the narrowing of the walls of the arteries. The condition must be diagnosed and treated early as it may get fatal.