Acute and chronic mesenteric ischaemia

Question 1

What is AMI?

Answer 1

• Sudden decrease in blood supply to the bowel –> ischaemia and if not treated, death

Question 2

4 classes of AMI

Answer 2

• Thrombus in situ - acute mesenteric arterial thrombus)
• Embolism - acute mesenteric embolism
• Non-occlusive - non-occlusive mesenteric ischaemia
• Venous occlusion and congestion - mesenteric venous thrombosis

Question 3

Cause of each class of AME

Answer 3

• AMAT - atherosclerosis
• AMAE - cardiac causes eg AF, post MI mural thrombi, prosthetic heart valve, thoraco-abdominal aneurysm
• NOMI - hypovolaemic shock, cardiogenic shock
• MVT - coagulopathy, malignancy, autoimmune disorders

Question 4

Symptoms of AMI

Answer 4

• Generalised abdominal pain - diffuse and constant
• Out of proportion to clinical findings
• Nausea and vomitting

Question 5

Examination of AMI

Answer 5

• Non-specific tenderness
• Globalised peritonism if perforated at later stages

Question 6

Other causes of generalised abdominal pain acutely

Answer 6

• PUD
• Bowel perforation
• Symptomatic AAA

Question 7

Bloods and bedside tests for AMI

Answer 7

• ABG - assess acidosis and lactate
• Routine bloods - FBC, U&E, clotting, amylase, LFT
• If coeliac trunk affected, ischaemia of liver can cause deranged LFTs
• Amylase also rises in AMI, ectopic pregnancy, bowel perf, and DKA as well as pancreatitis

Question 8

Imaging for AMI

Answer 8

• CT abdomen with IV contrast

Avoid oral contrast due to difficulty assessing for bowel wall enhancement

Question 9

CT signs of AMI

Answer 9

• Oedematous bowel - ischaemia and vasodilation
• Then progresses to loss of bowel wall enhancement - inadequate blood flow
• Then pneumatosis - infarction and then gas infiltration into mucosa

Question 10

Initial management AMI

Answer 10

• Surgical emergency = urgent resucitation and escalate to senior
• IV fluids
• Catheter + fluid balance chart
• Broad spec abx - risk of faecal contamination if perforates (bacterial translocation)
• Early ITU input - as very acidotic and high risk of organ failure

Question 11

Definitive management options for AMI

Answer 11

• Revasculariation of bowel
• Excision of necrotic/non-viable bowel - if not suitable for revasc

Question 12

How is decision made to revascularise bowel or not?

Answer 12

• State of patient
• Bowel
• Angiographic appearance of mesenteric vessels

Question 13

Management post op of excision of necrotic/non-viable bowel

Answer 13

• ITU
• Planned for potential re-look laparotomy in 24-48hrs
• Majority patients end up with loop or end stoma
• HIGH chance of short gut syndrome

Question 14

What is short gut syndrome?

Answer 14

• Bowel is shortened
• = Cannot absorb enough nutrients from the foods you eat to maintain health

Question 15

How is revasculularisation of bowel performed?

Answer 15

• Angioplasty is preferred
• Due to risk of aortic contamination in open surgery
• However open embolectomy is possible through the coeliac trunk, SMA, IMA or aorta

Question 16

Complications of AMI

Answer 16

• Bowel necrosis and perforation
• Mortality is high
• Those who survive often struggle with short gut syndrome

Question 17

What is chronic mesenteric ischaemia?

Answer 17

• Reduced blood supply to the bowel which gradually deteriorates over time
• Due to atheroscelrosis of coeliac trunk, SMA or IMA

Question 18

Typical patient with CMI

Answer 18

• Female
• Over 60yrs old
• Asymptomatic usually

Question 19

Pathophys of CMI

Answer 19

• Gradual build up of atherosclerotic plaque
• Narrows lumen
• Impairs blood flow
• = inadequate supply to bowel

Question 20

How many vessels to be affected to be symptomatic?

Answer 20

• Due to collateral blood flow, at least two of SMA, IMA and coeliac trunk must be affected
• Most likely with one vessel is occluded

Question 21

When can symptoms arise from CMI?

Answer 21

• At rest, asymptomatic due to decreased demand
• But when increased demand occurs can get symptoms eg when eating, or reduced blood volume following haemorrhage

Question 22

RF for CMI

Answer 22

• Smoking
• HTN
• Diabetes mellitus
• High cholesterol

Question 23

Symptoms if CMI becomes symptomatic

Answer 23

• Postprandial pain - 10mins-4hrs after eating (can then develop fear of eating - sitophobia)
• Weight loss - decreased calorie intake and malabsoprtion
• Other vascular co-morbids eg previous MI, stroke
• Can get changes to bowel habit (loose usually), N+V

Question 24

Examination findings CMI

Answer 24

• Malnutrition/cachexia
• Generalised abdominal tenderness
• Abdominal bruits

Question 25

Differentials for non-specific abdominal pain - more chronic

Answer 25

• Chronic pancreatitis
• Gallstone pathology
• PUD
• Upper GI malignancy

Question 26

Bloods for CMI

Answer 26

• Bloods are usually normal but routine bloods often checked
• Electrolytes magnesium and calcium should be checked due to malnutrition
• CV risk profile can be abnormal
• Anaemia can make symptoms worse

Question 27

Imaging for CMI

Answer 27

• CT angiography

Question 28

Initial management CMI

Answer 28

• Modify RF - smoking cesssation
• Antiplatelet and statin therapy

Question 29

Surgical options for CMI

Answer 29

• Endovascular angioplasty + stenting
• Open repair - endarterectomy or bypass
• Endovascular preferred due to general nutritional status of patients and complexity of open surgery

Question 30

When is surgery management considered for CMI?

Answer 30

• Severe disease
• Progressive disease
• Or debilitating symptoms eg weight loss/malabsoprtion

Question 31

How is mesenteric angioplasty performed?

Answer 31

• Percutaneously via femoral or brachial or axillary artery
• Cathter inserted under radiological guidance
• When region indentified, balloon expanded to dilate vessel
• Stenting placed to maintain vessel patency

Question 32

Risk of stenting CMI

Answer 32

• If stent blocks - can then develop acute mesenteric ischaemia

Question 33

Complications CMI

Answer 33

• Bowel infarction
• Malabsorption
• Concurrent CVD - needs managing
• But prognosis after intervention is good