What Is Mesenteric Ischemia?
Mesentery is a fold of membranes tissue that arises from the back wall of the peritoneal cavity and attaches to the intestinal tract. Within it are the arteries and veins that supply the intestine. Mesenteric organs include your stomach, liver, colon, and intestines. Mesenteric ischemia occurs when you have decreased blood flow to these organs as a result of narrowing or blockages. Mesenteric ischemia can be acute or chronic.
Acute mesenteric ischemia occurs by means of a sudden blockage of blood flow to your arteries, which can result in permanent damage to your intestines. This is an emergency situation requiring immediate medical attention.
Chronic mesenteric ischemia occurs gradually over time from narrowing in one or more of the arteries supplying blood to your intestines (visceral arteries). Patients may develop pain 15 to 60 minutes after eating, which makes it hard to eat regularly, resulting in weight loss. Patients also notice changes in their bowel movement frequency, as well as bloating, nausea, and vomiting.
Ischemia can also occur when blood can’t leave your intestines. In this instance, a blood clot can develop in a vein that drains deoxygenated blood from your intestines. When a vein is blocked, blood backs up in the intestines, resulting in swelling and bleeding. This is called mesenteric venous thrombosis.
Why Do I Have Mesenteric Ischemia?
There are several factors that can play a role in development of mesenteric ischemia. Chronic mesenteric ischemia may be caused by atherosclerosis or hardening of the arteries over time. Acute mesenteric ischemia may be caused by the following:
- A blood clot may dislodge from the heart as a result of congestive heart failure, arrhythmias or a heart attack
- Atherosclerosis (hardening of the arteries)
- Impaired blood flow from low blood pressure related to shock, heart failure, or kidney failure
- High blood pressure
- Illegal drug use such as cocaine or methamphetamine
- Blood clotting issues such as sickle cell anemia or anti-phospholipid syndrome
Mesenteric Venous Thrombosis may be caused by:
- Acute or chronic inflammation of the pancreas (pancreatitis)
- Abdominal infection
- Bowel diseases, such as ulcerative colitis, Crohn’s disease, or diverticulitis
- Disorders that make you more prone to blood clotting, such as inherited clotting disorder, or taking medications such as estrogen that can increase clotting risk
- Trauma to the abdomen
How Is Mesenteric Ischemia Diagnosed?
In order to confirm diagnosis, the physician uses a combination of physical examination and testing based on your signs and symptoms. When you are referred to a vascular surgeon, they will go over your history of smoking, high blood pressure, diabetes, and heart disease, as well as details about your symptoms. Tests that may be completed include the following:
- Blood testing: An increase in white blood cell count may indicate intestinal ischemia.
- Imaging such as a doppler ultrasound or CT angiogram: These may identify problems with your arteries or abdominal organs.
- Diagnostic angiogram: More invasive but preferred if diagnosis is very important. A long, thin tube is inserted into your groin or arm, then passed through an artery to your aorta. Dye is injected that can track the blood flow through the arteries and show if there are blockages.
What Are My Treatment Options for Mesenteric Ischemia?
The goal of treatment for mesenteric ischemia is to reopen the artery or vein to restore blood flow so that there is not permanent damage to the intestine. The specifics of your condition will guide the vascular surgeon as to whether treatment is emergent or elective.
Acute Mesenteric Ischemia Treatment (usually emergent):
- Narcotic pain medication
- Thrombolytic therapy: which is a clot dissolving drug, is injected into the artery
- Surgical removal of the clot and sometimes a part of the intestine if it has been damaged by lack of blood flow
Chronic Mesenteric Ischemia treatment:
- Pain medication
- Balloon angioplasty and stent oftentimes performed at the same time as the diagnostic angiogram
- Bypass surgery: a detour is created around the narrowed or blocked section of the affected artery
Mesenteric Venous Thrombosis Treatment:
- Blood thinners for 3-6 months, or longer if you are found to have a blood clotting disorder
- Surgery: if your bowel is showing signs of damage, it may require surgical removal.
How Can I Prevent Acute or Chronic Mesenteric Ischemia?
Acute and chronic mesenteric ischemia are caused by blockage of blood supply to the intestines, causing decreased oxygenation of these tissues. One or more branches of the mesenteric arteries are occluded, and if obstruction is complete, ischemia of the intestinal tissues progresses to necrosis, which is a surgical life-threatening emergency.
Prevention of Chronic Mesenteric Ischemia
Prevention of chronic ischemia to the intestines is via prevention of the underlying conditions that restrict blood flow over time:
- Atherosclerosis: The leading cause of chronic mesenteric ischemia, it will decrease blood flow by narrowing the lumen of the arterial supply. addressing the causes of atherosclerosis will also address these repercussions
- Smoking cessation: Strict glycemic control in diabetes. Correcting of dyslipidemia, and treatment of hypertension will mitigate atherosclerosis as a strategy to prevent mesenteric ischemia
- Acute ligament syndrome: In which the celiac artery is compressed by a ligament of the diaphragm, can be treated surgically
- Aortic or mesenteric artery dissection: Prevention of the natural progression of aneurysms is via the tactics that lower the risk of the dissection occurring or progressing, i.e., treating hypertension, and smoking cessation
- Vasculitis: Treatment includes steroid medication and other immunosuppressive protocols
Prevention of Acute Mesenteric Ischemia
The sudden small intestinal hypoxia from acute hypoperfusion, diagnosed by CT or imaging studies that demonstrate occlusion, can occur from the following which deprive intestinal tissue of blood supply distal to them:
- Embolus: Prevention is by management and treatment of cardiac arrhythmias and cardiac vascular disease, endocarditis, ventricular aneurysm, and aortic atherosclerosis and aneurysm. Anticoagulation is used for high-risk patients or those with recurrence.
- Thrombus: Prevention is by management and treatment of peripheral artery disease, especially in the elderly where age is a progressive risk factor.
- Vasospasm and transient severe hypotension: In unusual drops of blood pressure, the mesenteric arterial supply is vulnerable, such as in hypotensive periods of time during general or conductive anesthesia, or from acute blood loss in trauma.
Prevention of Mesenteric Ischemia Caused by Mesenteric Venous Thrombosis
Mesenteric venous thrombosis represents approximately 10% of all cases of acute mesenteric ischemia, caused by venous stasis due to stagnation, vascular injury, or coagulopathy. Thrombotic occlusion increases the vascular resistance in the mesenteric venous bed and this reduces arterial perfusion.
Prevention is by lowering the severity of risk factors for mesenteric venous thrombus formation:
- Treating abdominal inflammatory processes, e.g., pancreatitis, diverticulitis, and inflammatory bowel disease
- Addressing alcohol abuse, which causes portal hypertension and the increased venous pressure from cirrhosis
- Surgical removal of an abdominal mass responsible for venous compression
- History of deep vein thrombosis (DVT)