Mesenteric Ischaemia

Question 1

What is it?

Answer 1

Mesenteric ischaemia is caused by a lack of blood flow through the mesenteric vessels supplying the intestines, resulting in intestinal ischaemia.

Question 2

Blood supply of the bowel ?

Answer 2

The foregut includes the stomach and part of the duodenum, biliary system, liver, pancreas and spleen. This is supplied by the coeliac artery.

The midgut is from the distal part of the duodenum to the first half of the transverse colon. This is supplied by the superior mesenteric artery.

The hindgut is from the second half of the transverse colon to the rectum. This is supplied by the inferior mesenteric artery.

Question 3

What is chronic mesenteric ischaemia ?

Answer 3

Chronic mesenteric ischaemia (also known as intestinal angina) is the result of narrowing of the mesenteric blood vessels by atherosclerosis. This results in intermittent abdominal pain, when the blood supply cannot keep up with the demand. It is similar to the pathophysiology of angina, where the blood supply is reduced by coronary artery disease, resulting in intermittent symptoms.

Question 4

Presentation of chronic mesenteric ischaemia?

Answer 4

Central colicky abdominal pain after eating (starting around 30 minutes after eating and lasting 1-2 hours)
Weight loss (due to food avoidance, as this causes pain)
Abdominal bruit may be heard on auscultation

Question 5

Risk factors and diagnosis of chronic mesenteric ischaemeia ?

Answer 5

Increased age
Family history
Smoking
Diabetes
Hypertension
Raised cholesterol
Diagnosis is by CT angiography.

Question 6

Management of chronic mesenteric ischaemia?

Answer 6

Reducing modifiable risk factors (e.g., stop smoking)
Secondary prevention (e.g., statins and antiplatelet medications)
Revascularisation to improve the blood flow to the intestines

Revascularisation may be performed by:

Endovascular procedures first-line (i.e. percutaneous mesenteric artery stenting)
Open surgery (i.e endarterectomy, re-implantation or bypass grafting)

Question 7

What is acute mesenteric ischaemia?

Answer 7

rapid blockage in blood flow through the superior mesenteric artery. This is usually caused by a thrombus (blood clot) stuck in the artery, blocking blood flow. The blood clot may be a thrombus that has developed inside the artery or an embolus from another site that has got stuck in the artery.

Question 8

Key risk factor?

Answer 8

atrial fibrillation, where a thrombus forms in the left atrium, then mobilises (thromboembolism) down the aorta to the superior mesenteric artery, where it becomes stuck and cuts off the blood supply.

Question 9

Symptom of acute mesenteric ischaemia?

Answer 9

Acute mesenteric ischaemia presents with acute, non-specific abdominal pain. The pain is disproportionate to the examination findings. Patients can go on to develop shock, peritonitis and sepsis.
Over time, the ischaemia to the bowel will result in necrosis of the bowel tissue and perforation.

Question 10

Diagnosis and management of acute mesenteric iscaemia?

Answer 10

Contrast CT is the diagnostic test of choice, allowing the radiologist to assess both the bowel and the blood supply. Patients will have metabolic acidosis and raised lactate level due to ischaemia.

Patients require surgery to achieve two objectives:

Remove necrotic bowel
Remove or bypass the thrombus in the blood vessel (open surgery or endovascular procedures may be used)

There is a very high mortality (over 50%) with acute mesenteric ischaemia.