What is Mesenteric Artery Thrombosis?
Mesenteric artery thrombosis (MAT) is a serious condition where the blood supply to the intestinal system gets blocked. It mostly involves the superior mesenteric artery (SMA), which is the main artery supplying blood to the small intestine and part of the large intestine. This blockage typically results from a blood clot forming in the artery, often due to a disease that causes artery narrowing, like atherosclerosis. Alternatively, the blockage can come from a clot that formed elsewhere in the body and gets lodged in the SMA, often seen in patients suffering from irregular heart rhythms, like atrial fibrillation.
This illness can be very severe and even deadly, which highlights the importance of early detection and prompt treatment.
This summary mainly gives an overview of acute blockage in the superior mesenteric artery. Please note that other related conditions, such as chronic intestinal ischemia, mesenteric veno-occlusive disease, SMA syndrome, among others, are discussed separately.
What Causes Mesenteric Artery Thrombosis?
The main triggers of acute superior mesenteric artery thrombosis, a condition where the blood flow via one of the major arteries in the abdomen is blocked, are generally due to one of two factors:
- Hardened arteries (Atherosclerotic occlusion)
- A blockage that forms somewhere in the blood flow and becomes lodged in the artery (Embolic occlusion)
In fact, a study that examined bodies after death found that the ratio of these two causes was 1.4 to 1. Other, less common reasons such as vasculitis (inflammation of the blood vessels) and aortic dissection (a serious condition involving a tear in the wall of the aorta, the main blood vessel branching off the heart) can also be contributing factors.
Risk Factors and Frequency for Mesenteric Artery Thrombosis
Mesenteric Artery Thrombosis (MAT) is a medical condition that affects about 12.9 out of every 100,000 people every year. It is more commonly found in women and its likelihood increases exponentially as people age. This condition can cause blood clots in the Superior Mesenteric Artery (SMA), often leading to a more extensive decay of the intestines. Too, these blood clots can move further down the intestine depending on the size of the clot.
- Factors that increase the risk of MAT include:
- Atherosclerosis – a hardening and narrowing of the arteries.
- Arrhythmias, especially atrial fibrillation or an irregular heartbeat.
- Hypovolemia – a decrease in the volume of blood in your body, which can make your heart work harder.
- Cardiac disease – including congestive heart failure, recent heart attacks, and heart valve disease.
- Advanced age.
- Intra-abdominal cancer.
- Inflammatory Bowel Disease (IBD) – this has also been linked to an increase in acute mesenteric thrombosis.
Overall, this condition is estimated to be the reason for about 0.1% of all hospital admissions.
Signs and Symptoms of Mesenteric Artery Thrombosis
Mesenteric artery thrombosis is a health condition that often has similar symptoms among patients. The main problem people usually face is stomach pain, which is disproportionately intense compared to what a physical examination might suggest. This pain is usually described as moderate to severe, widespread, and constant. Along with abdominal pain, other symptoms like feeling sick, vomiting, diarrhea, and rectal bleeding sometimes occur.
In a medical study on acute mesenteric ischemia, which is often related, patients’ most common symptoms were:
- Abdominal pain (present in 95% of patients)
- Nausea (44% of patients)
- Vomiting (35% of patients)
- Diarrhea (35% of patients)
- Rectal bleeding (16% of patients)
There can be a quick worsening of these symptoms. Subtle signs of peritonitis, an inflammation of the lining of the abdominal cavity, can also appear. Early diagnosis is critical and primarily depends on a healthcare professional suspecting this condition based on the symptoms above.
Testing for Mesenteric Artery Thrombosis
Quick recognition and treatment are very important when dealing with mesenteric artery thrombosis, a condition where a blood clot forms in one of the major arteries that supplies blood to your intestines. Research shows that if this condition is diagnosed and treated within the first 24 hours, the survival rate is about 50%. But if the condition is not diagnosed and treated within this time frame, the chances of survival decrease to 30%.
With this in mind, your doctor might order a set of standard lab tests to help diagnose the issue. The most common results in these lab tests show a high concentration of red blood cells, signs of an abnormal metabolism typically characterized by excess lactic acid, and a high white blood cell count. Usually, high levels of potassium and phosphates in your blood are late signals of this condition and often mean that the condition has gotten to a point where it has affected your intestines.
Despite the availability of a myriad of diagnostic tools, traditional x-ray images of the abdomen aren’t particularly helpful in diagnosing mesenteric artery thrombosis. In the past, doctors relied heavily on a procedure known as mesenteric angiography, which helped visualize the blood vessels around the intestines. However, computed tomography angiography (CTA) – a special type of CT scan that can visualize blood vessels – has since replaced it due to its ability to provide detailed images of the blood vessels as well as the condition of the affected intestines.
Different signs that can be picked up by a CT scan, such as air in the abdomen, gas within the walls of the intestines, gas within the portal vein (the main blood vessel for the liver), and thickening of the intestinal wall, are critical in helping doctors decide the best course of treatment.
Alternatively, doctors might use magnetic resonance angiography (MRA) – a type of MRI used to visualize blood vessels – especially when it is not safe to use contrast materials. However, sometimes artifacts can affect the accuracy of this test, and the patient must stay still for a long time during the scan.
Duplex sonography – an ultrasound technique used to visualize the arteries – can also be used to check the blood flow in the mesenteric arteries. This can be particularly helpful for patients with severe kidney disease, where contrast materials could potentially worsen their kidney function. However, the effectiveness of duplex sonography can vary greatly depending on the operator’s skill and may be limited by difficulties in getting a good view of the arteries due to excess gas in the intestines.
Treatment Options for Mesenteric Artery Thrombosis
When diagnosed with mesenteric artery thrombosis, a condition where a blood clot blocks one of the major arteries that supplies blood to the intestines, quick and effective treatment is crucial. It’s important to stabilize the patient by replacing lost fluids in the body to correct low blood pressure and any imbalances in the body’s metabolism. If there are no strong reasons not to, a medicine called heparin sodium, which is a type of blood thinner, is typically administered through an IV to help stop the formation of blood clots.
Other medicines, like glucagon and papaverine, may be given to help manage the narrowing of blood vessels, which frequently happen alongside blood clots. Should there be signs of inflammation in the lining of the abdomen, this could mean damage to the intestines and would require urgent surgery. Depending on the source of the clot, different surgical procedures can be carried out. If the clot originated from somewhere else in the body, a surgical removal of the clot may be enough. However, if the clot was formed in-place due to a diseased vessel, a bypass may be necessary – this kind of surgery creates an alternative route for blood to flow. This is often done using a patient’s own vein to lower the risk of infection, especially if there is also a tear in the intestines. If necessary, removal of a portion of the damaged intestine may also be done at this time.
Occasionally, a secondary surgery might be needed to check the condition of the small intestine. In contrast, patients who have not yet displayed signs of inflammation inside the abdomen might be suitable for less invasive treatments. One such approach is the infusion of a clot-dissolving medicine, like tissue plasminogen activator (TPA), through a catheter placed inside the blocked artery. Some studies have shown this to be very effective in breaking down acute blood clots in mesenteric arteries. However, this procedure usually takes 12 to 24 hours to complete, and the potential benefits must be weighed against the time it takes to finish the treatment. This option should only be considered for stable patients. In recent times, catheter-directed clot removal procedures, which involve the use of small devices, have been used along with TPA. This method can shorten the treatment duration and has been promising in some cases.
What else can Mesenteric Artery Thrombosis be?
When someone has abdominal pain, which is a common symptom, there are many different health problems that could be the cause. These include, but are not limited to:
- Inflamed colon (acute colitis)
- Blockage in the bowel (bowel obstruction)
- A bulge or “ballooning” in the largest artery in your body that can burst (abdominal aortic aneurysm)
- A blockage in the ducts that carry bile from the liver (biliary obstruction)
- A hole in the wall of the intestine (intestinal perforation)
- Cancer (malignancy)
What to expect with Mesenteric Artery Thrombosis
The outlook for mesenteric artery thrombosis, a condition where blood clots block the vessels supplying blood to the intestines, is unfortunately not very positive. In a comprehensive retrospective study, it was discovered that about 56.6% of the patients faced complications within 30 days after surgery. Moreover, the death rate within these thirty days stood at 27.9%.
In individuals who underwent a procedure known as surgical revascularization, which is designed to improve blood flow to the intestines, the mortality rates reported were even higher, ranging from 44% to 90%.
Possible Complications When Diagnosed with Mesenteric Artery Thrombosis
Possible Complications:
- Short bowel syndrome: This is a condition where parts of the small intestine are missing or damaged.
- Colostomy: This is a surgery that brings one end of the large intestine through the abdominal wall to allow bowel movements outside the body.
- Multiorgan failure: This occurs when multiple organs in the body fail to function properly.
- Peritonitis: This is an inflammation of the membrane lining the inner wall of the abdomen.
- Occlusion of vein graft: This occurs when a vein graft is blocked, impeding blood flow.
- Death: In severe cases, the complications can lead to death.
