Mesenteric Ischemia: Causes, Symptoms, and Treatments

Mesenteric Ischemia

Mesenteric ischemia occurs when blood flow to the intestine decreases due to the pathology of the arteries. This ischemia can be very dangerous if it is not addressed properly in an emergency setting. An emergency radiological examination is also needed to make an assertive diagnosis and start management immediately.

Blood Supply of the Gut

• Foregut - Section up to mid-duodenum. It is supplied by the celiac artery, liver, and pancreas. 
• Midgut - From mid-duodenum to the right-sided colon. Supplied by the superior mesenteric artery. Most vulnerable to occlusion leading to ischemia. 

Hindgut - Comprises left-sided colon and rectum. The inferior mesenteric artery supports this.

The superior mesenteric artery divides into the mid-colic, right colic, and ileocolic arteries. An artery runs along the marginal artery of Drummond. One more artery that can play a major role is known as the Arc of Riolan. The arc of Riolan becomes prominent later. 

The Spectrum of Mesenteric Ischemia

• Acute ischemia
  • Acute mesenteric artery embolism (AMAE) - cardioembolic, atheromatous embolism from aorta - more than 50% of patients
  • Acute mesenteric artery thrombosis (AMAT) - 20 - 25% of patients
  • Non-occlusive mesenteric ischemia (NOMI) - 10-15 % of patients
    • If the patient has got shocked
    • Or patient with mesenteric artery spasms (cocaine, drugs)
  • Focal segmental ischemia - ileus/volvulus/obstruction
  • Mesenteric vein thrombosis (MVT) - < 5 % of patients
• Chronic ischemia
  • Intestinal angina - patients who typically present with abdominal pain after food consumption. The pain appears 2 to 3 hours after having food.
  • Ischemic colitis
• The most commonly affected artery is the superior mesenteric artery.

Risk Factors for Mesenteric Ischemia

• Hypertension
• Diabetes mellitus
• Dyslipidemia
• Hyperhomocysteinemia
• Left Ventricular Hypertrophy (LVH)
• Left Atrial Enlargement (LAE)
• Atrial fibrillation 
• Proxismal Supra Ventricular Tachycardia (PSVT) 
• Thrombophilic states (acquired or inherited)
• Age is also an important risk factor (usually above 60 years)

Clinical Features Of Mesenteric Ischemia

• Chronic is asymptomatic at rest
• Acute abdominal pain will be diffused
• Development of abdominal distension
• Perforation can lead to hypotension or shock 

Diagnosis Of Mesenteric Ischemia

Diagnosing mesenteric ischemia is very important for proper diagnosis and treatment. Due to advancements in nuclear medicine, many techniques can help us get a clear picture of the problem area. Doppler can be used, but it is an observer-dependent scan, so it cannot be an investigation of choice. The most reliable scan is an abdominal X-ray showing bowel wall edema. This is a pathognomic sign known as the “thumbprinting sign”  due to the spasm of a contracted segment of the bowel on an X-ray. In the case of perforation of the intestine due to prolonged ischemia, there is the gas under the diaphragm, which can be easily observed using an  Abdominal X-ray as well.

The Preferred investigation in the case of mesenteric ischemia is CECT of the abdomen with CTA without oral contrast. This gives a very clear picture of the pathology. 

Differential Diagnosis Of Mesenteric Ischemia

• Colitis- inflammation of the colon
• A ruptured abdominal aortic aneurysm (AAA) is the ballooning of a certain area of the aorta in the abdomen. 
• Bowel Obstruction- Bowel obstruction is the incomplete or complete obstruction of the small or large intestine, that is, the bowel.
• Diabetic Ketoacidosis 
• Gastrointestinal Perforation
• Malignancy

Management Of Mesenteric Ischemia

The Investigation of choice in mesenteric ischemia is CTA without oral contrast. An arterial blood gas(ABG) should also be done urgently to determine the changes in the blood due to ischemia.

It is very important to start Resuscitation with intravenous fluid. Here, the fluid of choice will be crystalloids. A blood transfusion could be needed if the hemoglobin is less than 7 gms/dL. If there is a clot, it needs to be treated with Heparin.

The Definitive management of mesenteric ischemia is Revascularization. This is an Endovascular approach where an open embolectomy and thrombolysis can be considered if a patient presents within 8 hours. There is Bowel necrosis if the ischemia is not addressed. This necrosed area needs resection and has a low threshold for exploration. It is also important to start broad-spectrum antibiotics so that the infections and their related complications can be avoided.

Frequently Asked Questions 

Question: Which artery is most vulnerable to ischemia?

Answer: Superior mesenteric artery

Question: Which part of the bowel is affected?

Answer: The right side of the bowel.

Also Read: Achalasia Cardia- Clinical Features, Diagnosis And Treatment

Hope you found this blog helpful for your NEET SS Gastroenterology and Hepatobiliary preparation. For more informative and interesting posts like these, keep reading PrepLadder’s blogs.