Mesenteric Ischaemia and Ischaemic Hepatitis

Question 1

Mesenteric Ischaemia

Answer 1

Mesenteric ischaemia is primarily caused by arterial embolism resulting in infarction of the colon. It is more likely to occur in areas such as the splenic flexure that are located at the borders of the territory supplied by the superior and inferior mesenteric arteries.

Question 2

Mesenteric Ischaemia - Predisposing Factors

Answer 2

Predisposing factors
increasing age
atrial fibrillation
other causes of emboli: endocarditis
cardiovascular disease risk factors: smoking, hypertension, diabetes
cocaine: ischaemic colitis is sometimes seen in young patients following cocaine use

Question 3

Mesenteric Ischaemia - Features

Answer 3

Features
abdominal pain
rectal bleeding
diarrhoea
fever
bloods typically show an elevated WBC associated with acidosis

Question 4

Mesenteric Ischaemia - Mx

Answer 4

Management
supportive care
laparotomy and bowel resection

Question 5

Mesenteric Ischaemia: Example Question

Answer 5

An 80 year-old man presents with a 3 month history of generalised abdominal pain and a change in bowel habit. The abdominal pain is colicky in nature and does not radiate anywhere. He also reports increasing distension of his abdomen and 2 episodes of blood in the rectum several weeks ago. He has recently undergone colonoscopy, which did not reveal anything abnormal. His past medical history includes diabetes type 2 and a heart attack two years ago, for which he needed three stents. His mother died of a stroke when he was 60 and his father died of a heart attack at the age of 55. His current medications include ramipril, aspirin, atenolol, atorvastatin and metformin. He has a 40 year pack history and drinks on average 15 units per day.

Blood tests reveal:

Hb	12.0 g/dL
Mean corpuscular volume (MCV)	80 fl
Platelets	198 * 109/l
WBC	13.1 * 109/l
Na+	132 mmol/l
K+	5.1 mmol/l
Urea	9.0 mmol/l
Creatinine	145 µmol/l

Other than an abdominal x-ray, what is the most appropriate investigation?

	> Contrast-enhanced computed tomography (CT) of the abdomen with angiography
	Colonoscopy
	Endoscopy
	MRI of the abdomen
	Angiography

Given this man’s cardiac history, age and the length of clinical features, the most likely diagnosis is chronic mesenteric ischaemia - the cause is probably atheroma of the mesenteric vessels, as opposed to embolism. The patient’s creatinine levels start to rise in response to bowel wall ischaemia, hence the apparent affect on renal function.

A plain-film abdominal x-ray is often valuable in excluding certain abdominal conditions, although CT of the abdomen with angiography is the preferred investigation. Angiography gives information regarding a proximal defect of a mesenteric vessel or vasoconstriction of all mesenteric arcades and the CT scan provides information on bowel wall thickening, bowel dilation and the classic thumb-printing sign suggestive of submucosal oedema or haemorrhage.

Question 6

Ischaemic Hepatitis

Answer 6

Diffuse hepatic injury resulting from Acute Hypoperfusion
Sometimes known as SHOCK LIVER

Usually diagnosed in the presence of an inciting event e.g. Cardiac arrest

= Marked increases in aminotransferase levels (exceeding 1000 international unit/L or 50x upper limit of N)

Often occurs in conjunction w AKI (tubular necrosis) or other end organ dysfunction

NB Ultrasound typically Normal!