Intestinal Ischaemia

Question 2

Ischaemia to the lower gastrointestinal tract can result in a variety of clinical conditions. Whilst there is no standard classification it can be useful to separate cases into which 3 main conditions?

Answer 2

acute mesenteric ischaemia
chronic mesenteric ischaemia
ischaemic colitis (aka chronic colinc ischaemia)

Question 3

Describe why acute mesenteric ischaemia usually occurs [2]

Answer 3

Thrombus to the superior mesenteric artery

A key risk factor is 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.

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Question 4

The common causes of acute mesenteric ischaemia can be classified into [4]

Answer 4

Thrombus-in-situ (Acute Mesenteric Arterial Thrombosis, AMAT)

Embolism (Acute Mesenteric Arterial Embolism, AMAE)

Non-occlusive cause (Non-Occlusive Mesenteric Ischemia, NOMI)

Venous occlusion and congestion (Mesenteric Venous Thrombosis, MVT)

Question 5

Describe the arterial supply to the gut [3]

Answer 5

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 6

Describe the presentation of acute mesenteric ischaemia [2]

Answer 6

Acute mesenteric ischaemia presents with triad of:
- acute, non-specific abdominal pain - constant
- no / minimal abdominal signs
- rapid hypovalamia & shock

The pain is disproportionate to the examination findings.

Patients can go on to develop shock, peritonitis and sepsis.

Question 7

How does acute mesenteric ischaemia present on an AXR? [1]

Answer 7

‘Gasless abdomen’

Question 8

How do you treat acute mesenteric ischaemia? [5]

Answer 8

• PassMed ‘Acute mesenteric ischaemia usually requires an immediate laparotomy, particularly if signs of advanced ischemia e.g. peritonitis or sepsis’
• Fluids
• Antibiotics
• LMWH
• Dead bowel removed in surgery
• Revascularistion in surgery

Question 9

How will blood gasses change in acute mesenteric ischaemia? [2]

Answer 9

Patients will have metabolic acidosis and raised lactate level due to ischaemia.

Question 10

What is the diagnostic test of choice for acute mesenteric ischaemia? [1]

Answer 10

Contrast CT is the diagnostic test of choice, allowing the radiologist to assess both the bowel and the blood supply.

Question 11

Describe the initial [3] and definitive [2] mangement for acute mesenteric ischaemia

Answer 11

Initial Management:
- surgical emergency, requiring urgent resuscitation with early senior involvement
- IV fluids, a catheter inserted, and a fluid balance chart started
- In confirmed cases: broad-spectrum antibiotics should be given, due to the risk of faecal contamination in case of perforation of the ischaemic (and potentially necrotic) bowel and bacterial translocation.

Definitive Management:
- Excision of necrotic or non-viable bowel
- Revascularisation of the bowel - preferably done through angioplasty

Question 12

What is the definitive diagnosis for acute mesenteric ischaemia?

Answer 12

Definitive diagnosis is made via CT angiography

Question 13

The main risks from mesenteric ischaemia are [2]

Answer 13

The main risks from mesenteric ischaemia are bowel necrosis and perforation.

Question 14

Chronic mesenteric ischaemia aka? [1]

Answer 14

intestinal angina

Question 15

What is the triad of symptoms for chronic mesenteric ischaemia? [3]

Answer 15

Severe colicky, post-prandial pain
Decrease weight
Upper abdominal bruit
Concurrent vascular co-morbidities, e.g. previous MI, stroke, or PVD

Question 16

What causes chronic mesenteric ischaemia? [1]

Answer 16

Low flow state to mesentary due to atheroma

Question 17

Diagnosis of chronic mesenteric ischaemia? [1]

Answer 17

Diagnosis is by CT angiography.

Question 18

Describe the mangement of chronic mesenteric ischaemia [4]

Answer 18

Initial management:
- Modify risks (stop smoking; healthy diet)
- commence clopridogrel and aspirin 80mg

Surgical management
- Endovascular procedures: percutaneous transluminal angioplasty & stent insertion
- Open procedures (less common) – either an endartectomy or a bypass procedure

Question 19

Describe how the mechanism of mesenteric angioplasty [2]

Answer 19

Mesenteric angioplasty is performed percutaneously, through either the femoral artery or brachial/axillary artery, allowing a catheter to be passed to the appropriate vessel under radiological guidance.

Once the affected region is identified, a small balloon is expanded to dilate the vessel, and stenting typically undertaken to maintain vessel patency.

Question 20

Which of the following patient’s has a presentation most in keeping with chronic mesenteric ischaemia?

30yr old female, no PMH and BMI 34, presents to GP with RUQ pain 2 hours post eating, especially with fatty foods

71yr old male, PMH prior MI and stroke, ex-smoker, presents to GP with severe abdo pain 2 hours post eating

56yr old male, PMH asthma, present to A&E with severe central abdominal pain following ETOH excess

82yr old male, PMH HTN, current smoker, presents to A&E with sudden onset abdominal and back pain

Answer 20

Which of the following patient’s has a presentation most in keeping with chronic mesenteric ischaemia?

30yr old female, no PMH and BMI 34, presents to GP with RUQ pain 2 hours post eating, especially with fatty foods

71yr old male, PMH prior MI and stroke, ex-smoker, presents to GP with severe abdo pain 2 hours post eating

56yr old male, PMH asthma, present to A&E with severe central abdominal pain following ETOH excess

82yr old male, PMH HTN, current smoker, presents to A&E with sudden onset abdominal and back pain

Question 21

Ischaemic colitis occurs due to reduced flow in which artery? [1]

Answer 21

IMA

Question 22

How does ischaemic colitis present? [2]

Answer 22

Lower left sided abdomen pain
+/- bloody diarrhoea

Question 23

Gold standard for ischaemic colitis? [1]

Answer 23

Lower GI endoscopy

Question 24

Tx for ischaemic colitis? [2]

Answer 24

Fluids & AB

Question 25

Where is ischaemic colitis most likely to occur? [1]

Answer 25

It is more likely to occur in ‘watershed’ areas such as the splenic flexure that are located at the borders of the territory supplied by the superior and inferior mesenteric arteries.

Question 26

Describe the typical presentation of mesenteric ischaemia [1]

Answer 26

Traditionally, mesenteric ischaemia presents with a generalised abdominal pain, out of proportion to the clinical findings, although it can often be more variable or subtle than this.

The patient will typically complain of a diffuse and constant pain, with associated nausea and vomiting in around 75% of cases.

Importantly, take note of any potential embolic sources, such as atrial fibrillation or heart murmurs, that may provide a suggestion to the underlying cause

Question 27

The SMA and IMA contribute to the formation of the [] a vessel that runs along the inner margin of the colon providing branches to the bowel wall. It receives contributions from the ileocolic, right, middle and left colic arteries. It is at times absent or very small at the splenic flexure and is less well developed at the sigmoid region.

Answer 27

The SMA and IMA contribute to the formation of the marginal artery of Drummond, a vessel that runs along the inner margin of the colon providing branches to the bowel wall. It receives contributions from the ileocolic, right, middle and left colic arteries. It is at times absent or very small at the splenic flexure and is less well developed at the sigmoid region.