Intestinal ischemia

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Overview

Bowel ischemia can affect a small or large intestine and can occur by any cause, which leads to intestinal blood flow reduction. This is an uncommon medical condition, but it has a high mortality rate. The intestine is mainly supplied by 2 major arteries, which include the superior mesenteric artery (SMA) and the inferior mesenteric artery (IMA). The SMA supplies the bowel from the lower part of the duodenum to two-third of the transverse colon. The IMA supplies a large intestine from the distal one-third of the transverse colon to the rectum. The celiac artery also has collaterals to supply the intestine. Bowel ischemia can be classified as small intestine ischemia, which is commonly known as mesenteric ischemia and large intestine ischemia, which generally referred to as colonic ischemia. Two main areas in the colon, including splenic flexure (Griffiths point) and rectosigmoid junction (Sudek's point), are prone to ischemia. These are also known as the 'watershed' areas, which mean the regions in the colon between 2 major arteries that supplying colon. Splenic flexure is the area between SMA and IMA supplies, and the rectosigmoid junction is the region between the IMA and the superior rectal artery supplies. These areas mostly supplied by the marginal artery; however, in 50% of the population, this artery is poorly developed. Watershed areas account for about 70% of ischemic colitis cases. The colon venous drainage is the parallel of arterial supply. The superior mesenteric vein drains the areas supplied by SMA, and an inferior mesenteric vein drains the left side of the colon and the rectum. An acute decrease in mesenteric arterial blood flow accounts for 60% to 70% of patients with mesenteric ischemia. The rest of the causes are related to colonic ischemia and CMI. Abdominal pain is the most common symptom in patients with intestinal ischemia. Some features of a patient can help to distinguish between the acute small bowel and colonic ischemia. Patient's characteristics, such as age over 60 years, not appearing severe ill, mild abdominal pain, tenderness, rectal bleeding, or bloody diarrhea, are the features that are more common in acute colonic ischemia. Generally, an abdominal computed tomography (CT) scan is used in hemodynamically stable patients who present with acute abdominal pain. In patients with high suspicious for intestinal ischemia, CT angiography and MR angiography are the initial tests. Based on acute mesenteric ischemia (AMI) subtypes, different medication treatments have been suggested. Papaverine, through the angiographic catheter with the mechanism of relaxation of vessels vasospasm, can be used for all arterial forms of AMI and nonocclusive mesenteric ischemia.

Symptoms

Abdominal cramps or fullness, usually 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.

Bloating.

Causes

Intestinal ischemia usually occurs when one of two major arteries becomes obstructed: the superior mesenteric artery (SMA), which supplies most of the small intestine; or the inferior mesenteric artery (IMA) the major supplier of the large intestine. Sometimes a blockage in the venous drainage from the intestines can also lead to intestinal ischemia.


There are several general vascular conditions that can cause acute intestinal ischemia. These include:


Arterial embolism: An embolus—a blood clot that breaks loose and travels through the circulation—can become lodged in a mesenteric artery, causing a blockage. Because an embolus tends to be a sudden event, symptoms are usually acute and quite severe. Embolism is estimated to be the cause of about half the cases of intestinal ischemia.

Arterial thrombosis: A thrombus (a blood clot that forms within a blood vessel) probably accounts for 25% of cases of acute intestinal ischemia. Similar to coronary artery thrombosis, thrombosis of the mesenteric arteries seems to occur when an atherosclerotic plaque in the lining of the artery ruptures. Just as people with coronary artery disease will often experience intermittent angina with exertion before they have an actual heart attack, people with thrombosis of a mesenteric artery will often describe prior symptoms of intermittent abdominal pain following meals—so-called "intestinal angina."

Venous thrombosis: If one of the veins draining blood from the intestines (the mesenteric veins) becomes blocked, blood flow through the affected intestinal tissue slows markedly, leading to intestinal ischemia. This condition is most often seen in people who have had recent abdominal surgery or cancer.

Nonocclusive intestinal ischemia: Sometimes, blood flow through the mesenteric arteries drops markedly without any local blockages at all. This condition is usually seen in people who are severely ill and in shock, most often from severe cardiac disease or sepsis. In these catastrophic conditions, circulating blood is shunted away from "non-vital" organs in favor of the heart and brain and, as a result, intestinal ischemia may occur.

Risk factors

Almost any form of cardiac disease, vascular disease, or disorders of blood clotting can increase a person's risk of developing intestinal ischemia.


In particular, the risk of intestinal ischemia increases with:


Heart disease: This includes heart valve disease, atrial fibrillation, or cardiomyopathy. These conditions allow blood clots to develop within the heart, which can then embolize. While stroke is the main concern of doctors and patients when blood clots form in the heart, an embolus from the heart can also cause acute intestinal ischemia.

Peripheral artery disease (PAD): When PAD involves the mesenteric arteries, intestinal ischemia can result.

Blood clotting disorders: Inherited blood clotting disorders, such as factor V Leiden, account for the majority of people who have intestinal ischemia without underlying vascular disease.

Hypovolemia, or low blood volume: Reduced blood volume can be caused by excessive bleeding, severe dehydration, or cardiovascular shock, and can produce nonocclusive intestinal ischemia.

Inflammation of the blood vessels: Vasculitis (inflammation of blood vessels) can be produced by infections or autoimmune disorders such as lupus. The vascular inflammation can lead to thrombosis of the mesenteric arteries.

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Complications

Death of intestinal tissue. If blood flow to your intestine is completely and suddenly blocked, intestinal tissue can die (gangrene).

Perforation. A hole through the wall of the intestines can develop. ...

Scarring or narrowing of your colon.

Prevention

Quit Smoking. One of the best ways to prevent or halt the progression of atherosclerosis, which can lead to mesenteric ischemia, is to quit smoking. ...

Maintain Healthy Blood Pressure and Cholesterol Levels. ...

Exercise Regularly. ...

Control Diabetes.