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VASCULAR (GI) Flashcards

1
Q

What is ischaemic colitis?

A

Ischaemia of the colon i.e. reduced blood flow to insufficient levels

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2
Q

What is mesenteric ischaemia?

A

Ischaemia affecting the small intestines - i.e. reduced blood flow to insufficient levels

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3
Q

What are the 2 broad categories of causes of colonic ischaemia?

A

Occlusive - thrombosis or embolus
Non-occlusive - vasoconstriction and hypoperfusion (more common)

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4
Q

Whats the most common form of intestinal ischameia?

A

Ischaemic colitis

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5
Q

Whats the blood supply to the duodenum?

A

The proximal segment of the duodenum is supplied by the gastroduodenal artery and its branches which include the duodenal branches and the superior pancreaticoduodenal artery.
The distal segment of the duodenum is supplied by the anterior and posterior inferior pancreaticoduodenal arteries (branches of SMA).

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6
Q

Whats the blood supply to the jejunum and ileum?

A

SMA - 15-18 of its branches which form anastomoses loops called arterial arcades with the terminal vasa recta

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7
Q

Whats the blood supply to the ascending colon?

A

Ileocolic and right colic arteries (branches of SMA)

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8
Q

Whats the blood supply to the transverse colon?

A

Right colic artery from SMA
Middle colic artery from SMA
Left colic artery from IMA

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9
Q

Whats the blood supply to the descending colon?

A

Left colic artery (IMA)

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10
Q

Whats the blood supply to the sigmoid colon?

A

Sigmoid arteries (branches of IMA)

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11
Q

What are the branches of the SMA which supply the colon?

A

Ileocolic artery
Right colic artery
Middle colic artery

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12
Q

What are the branches of the ileocolic artery?

A

Inferior and superior branch

Inferior branch divides into anterior and posterior faecal arteries, appendiceal artery and ileal branch
Superior branch passes upwards and anastomoses with the right colic artery

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13
Q

What are the branches of the right colic artery?

A

Ascending branch and descending branch

Ascending branch anastomoses with middle colic artery
Descending branch anastomoses with superior branch of ileocolic artery

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14
Q

What are the branches of the middle colic artery?

A

Left and right branch

Left branch anastomoses with left colic artery at the splenic flexure
Right branch anastomoses with right colic artery
(Middle branch may be present!)

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15
Q

What are the branches of the IMA?

A

Left colic artery
Sigmoid artery
Superior rectal artery

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16
Q

What are the branches of the left colic artery?

A

Ascending and descending branches

Ascending branch anastomoses with branches of the middle colic artery
Descending branches meet sigmoid arteries below

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17
Q

How many sigmoid arteries are there?

A

Variable number - usually 2-5

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18
Q

What do the sigmoid arteries supply?

A

Distal descending colon and sigmoid colon

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19
Q

What does the superior rectal artery supply?

A

Upper 2/3rds of the rectum

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20
Q

Where do middle and inferior rectal arteries arise from?

A

Middle - internal iliac artery
Inferior rectal arteries are a continuation of the internal pudendal arteries

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21
Q

What is the marginal artery of Drummond?

A

An anatomically variable blood vessel
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

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22
Q

What is non-occlusive colonic ischaemia?

A

characterised by reduced perfusion to the colon not explained by occlusive lesions. It is the most common cause of colonic ischaemia though is normally transient. If prolonged it can result in bowel wall necrosis.

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23
Q

Where does non-occlusive colonic ischaemia tend to affect and why?

A

It most commonly affects watershed regions where collateral blood supply is poor - the splenic flexure and rectosigmoid junction.

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24
Q

What are the risk factors for non-occlusive colonic ischaemia?

A

Heart failure (low output state)
Septic shock
Vasopressors (e.g. noradrenaline, cause vasoconstriction)
Recent CABG
Renal impairment
Peripheral vascular disease
Cocaine use

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25
What is occlusive colonic ischaemia?
characterised by physical impedance of the arterial supply or venous drainage. It occurs relatively rarely in isolation to the colon, with the small intestines commonly also affected. Arterial occlusion - secondary to thrombosis or embolism Venous thrombosis
26
What are the arterial types of occlusive colonic ischaemia?
Mesenteric arterial embolism (50% of all cases) Mesenteric arterial thrombosis (25% of all cases)
27
Who does mesenteric arterial embolism causing colonic ischaemia typically affect?
Elderly patients with AF Other risk factors for emboli disease - infective endocarditis, arrhythmias, left ventricular aneurysm, proximal atherosclerotic disease, prosthetic heart valves (Think cardiac causes!)
28
Who does mesenteric arterial thrombosis typically occur in?
Vasculopaths with other cardiovascular disease Other risk factors - PVD, advancing age, iatrogenic trauma e.g. during surgery, heart failure (Cause is atherosclerosis)
29
How does a mesenteric arterial embolism present?
Severe acute left sided abdominal pain
30
How does mesenteric arterial thrombosis causing colonic ischaemia typically present?
They may have a background of chronic mesenteric ischaemia as characterised by abdominal pain following food and weight loss Pain is moderate/severe, diffuse and constant
31
How can thrombosis in mesenteric veins cause colonic ischaemia?
Venous thrombosis impedes flow and causes stagnation leading to bowel wall oedema and eventual impairment of arterial supply When it occurs it typically affects the superior mesenteric vein drainage affecting the small intestines and proximal colon. It may occur for a number of reasons including local inflammatory processes (e.g. pancreatitis) and thrombophilia’s.
32
Other than thrombi and emboli, what else can cause colonic ischaemia?
Bowel obstruction - most commonly volvulus Hypovolaemic shock Cardio genie shock
33
What are the clinical features of acute mesenteric ischameia?
Generalised, acute abdominal pain out of proportion to clinical findings - diffuse and constant Associated nausea and vomiting in 75% of cases Non-specific tenderness only on examination Globalised peritonism once bowel perforated Pyrexia/fever Tachycardia Haemodynamic instability Signs of shock May have AF or murmurs on examination - suggest underlying cause as potential embolic sources
34
What investigations are done for acute mesenteric ischaemia?
Routine bloods (FBC, renal function, LFTs, CRP, clotting screen, BG, group and save, VGB or ABG) - show inflammatory response, raised lactate and amylase and metabolic acidosis CT with IV contrast Colonoscopy
35
What can be seen on CT for acute mesenteric ischaemia?
Oedematous bowel Later - loss of bowel wall enhancement and then pneumatosis
36
What are the main risk factors for chronic mesenteric ischaemic?
Smoking Hyperlipidaemia Hypertension Diabetes FHx Increased age (Others depend on underlying cause)
37
What are the 4 types of acute mesenteric ischaemic?
Acute mesenteric arterial thrombosis AMAT Acute mesenteric arterial embolism AMAE Non-occlusive mesenteric ischaemia NOMI Mesenteric venous thrombosis MVT
38
What causes chronic mesenteric ischaemia?
Reduced blood supply to bowel which gradually deteriorates overtime due to atherosclerosis in coeliac trunk, SMA or IMA
39
Who does chronic mesenteric ischaemia tend to affect?
>60 Females Smokers Those with hypertension, diabetes mellitus or hypercholesterolemia
40
Why do you get symptomatic and asymptomatic variations of chronic mesenteric ischaemia?
The gradual build-up of atherosclerotic plaque within the mesenteric vessels narrows the lumen, impairing blood flow to the supplied viscera, resulting in an inadequate blood supply to the bowel. However, collateral blood supply means that commonly at least two of the Coeliac, SMA, and IMA must be affected for the patient to be symptomatic, most likely with at least one vessel occluded. Note at rest pt are typically asymptomatic but any increased demand on blood supply will exacerbate symptoms e.g. after eating or severe haemorrhage
41
What are the clinical features of chronic mesenteric ischaemia?
Postprandial central, colicky abdo pain - 10 mins-4 hours after eating Weight loss due to food avoidance Abdominal bruit heard on auscultation Concurrent vascular comorbidities Others - change in bowel habit (typically loose), nausea and vomiting
42
What investigations are done for chronic mesenteric ishcameia?
Routine bloods - typically normal Other than anaemia and cardiovascular risk profile factors may be abnormal (lipids profile and BG) CT angiogragram is the diagnostic test of choice
43
Why may LFTs be deranged in acute mesenteric ischaemia?
If the coeliac trunk is affected then ischaemia of the liver may cause derangement
44
why is amylase elevated in acute mesenteric ischemia
It’s an acute phase reactant
45
How do we initially manage acute mesenteric ischameia?
Urgent resuscitation with IV fluids, catheter, fluid balance chart started Broad spectrum antibiotics due to risk of faecal contamination in case of bowel perf and bacterial translocation Early ITU input
46
Why do pt with acute mesenteric ischameia need early ITU input?
pt will have significant acidosis (due to tissue hypoperfusion) and is at high risk of developing multi-organ failure
47
How do we definitively manage acute mesenteric ischaemic?
Excision of necrotic/non-viable bowel Revasculariation of bowel by removing thrombus or embolism via radiological intervention
48
What are the complications of mesenteric ischaemic?
Bowel necrosis Bowel perforation Short gut syndrome
49
Whats the mortality rate for acute mesenteric ischaemic?
50-80%
50
What is short gut syndrome?
a condition in which your body is unable to absorb enough nutrients/fluid from the foods you eat because you don't have enough small intestine
51
Whats the management for chronic mesenteric ischaemic?
Modify risk factors - smoking cessation, losing weight etc Secondary prevention - antiplatelets, statin therapy Surgical treatment - endovascular (more common) or open procedure revascularisation
52
What indicates surgical intervention for chronic mesenteric ischaemia?
Severe disease Progressive disease Presence of debilitating symptoms - weight loss or malabsorption signs
53
What is the endovasuclar procedure done for chronic mesenteric ischaemia?
Mesenteric angioplasty with stenting (percutaneous mesenteric artery stenting)
54
What open procedures can be done for chronic mesenteric ischaemic?
Endartectomy, re-implantation of blood vessel or a bypass procedure
55
What is mesenteric angioplasty? What are the pros and cons?
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. Such procedures provide a shorter hospital stay with faster mobilisation for the patient. However, if the stent occludes at any point, the patient can develop acute mesenteric ischaemia.
56
What are the main complications of chronic mesenteric ischaemia?
Bowel infarction Malabsorption Concurrent cardiovascular disease
57
What is ‘intestinal angina’?
Chronic mesenteric ischaemia
58
When might pt with acute mesenteric ischaemia?
To remove necrotic bowel tissue To remove or bypass the thrombus in the blood vessel - open or endovascular procedures
59
Where do abdominal aortic aneurysm most commonly occur?
Below the renal arteries (infrarenal)
60
What proportion of the population over 60 are AAA present in?
5%
61
Who is most likely to be affected by an AAA?
Men (6 times more likely) 12x more likely if you have a first degree relative affected
62
What are the causes of AAA?
Secondary to atherosclerosis, infections, trauma, inflammatory disease Genetic - Marfan syndrome or ehlers-danlos syndrome
63
What is an aneurysm?
an abnormal dilatation of a blood vessel by more than 50% of its normal diameter.
64
What is an AAA?
a dilatation of the abdominal aorta greater than 3cm.
65
What are the risk factors for AAA?
Age Male Atherosclerotic disease FHx Smoking Hypertension Connective tissue disorders Less likely - infections, inflammatory diseases, trauma
66
Does diabetes mellitus increase your risk of developing AAA?
No, evidence has demonstrated a negative association between the 2 diseases
67
Whats the prognosis of a ruptured AAA?
80%
68
What infections can cause an AAA?
Infectious aortitis - syphilis, salmonella, E.coli, staphylococcus
69
Who is there screening for AAA?
Men at age 65 Women over 70 with high risk factors e.g. existing CVD, FHx, COPD, hypertension, hyperlipidaemia or extensive smoking history
70
What is done during screening for an AAA?
Abdominal ultrasound scan - 2 AP measurements of the maximum aortic diameter recorded
71
Outline what happens with the results of the abdominal USS for screening for AAA?
< 3cm: No further follow-up required 3cm - 4.4cm: GP to give lifestyle advice. Follow up in 1 year. Refer to regional vascular service to be seen in 12 weeks 4.5cm - 5.4cm: advise 3 monthly screening with USS, give lifestyle advice and give cardiovascular secondary prevention therapy. Refer to regional vascular service to be seen in 12 weeks > 5.4cm: requires urgent two-week wait referral to vascular surgery to discuss management.
72
What are the symptoms and signs of an AAA?
Most asymptomatic and found on routine tests Rapid expansion or rupture of an AAA may cause severe epigastric pain radiating to the back Ruptures AAA causes hypotension, tachycardia, profound anaemia, sudden death Pulsation expansive abdominal mass Non-specific back pain can sometimes occur due to gradual erosion of vertebral bodies Acute limb ischaemia if aneurysm embolizes Trash feet - dusky decolourisation of digits secondary to emboli from aortic thrombus
73
How is an AAA diagnosed?
Obs, ECG, urine dip FBC, U&E, LFT, clotting screen, ABG/VBG, group and save ***Ultrasound ***CT angiogram for more detailed picture Abdominal x-ray? (*** most important!)
74
Classify AAA?
Normal <3cm Small 3-4.4cm Medium 4.5-5.4cm Large >5.5cm
75
How are AAAs managed conservatively?
Stopping smoking Healthy diet, exercise and weight loss Optimising management of hypertension, diabetes and hyperlipidaemia Commence statin and aspirin therapy - secondary prevention!
76
What are the indications for surgery to repair an AAA?
AAA >5.5cm diameter AAA expanding at >1cm/year Symptomatic AAA in a pt who is otherwise fit
77
Outline the surveillance for AAA <5.5cm?
Yearly USS for patients with aneurysms 3-4.4cm 3 monthly USS for patients with aneurysms 4.5-5.4cm
78
What are the 2 methods for inserting the artificial graft for an AAA? What are the pros and cons of each?
Open repair via laparotomy Endovascular aneurysm repair (EVAR) After 2 years the mortality for both procedures is the same EVAR has an improved short outcome for decreasing hopsital stay and 30 day mortality but a higher rate of re intervention and aneurysm rupture Therefore, in young fit pt, an open repair may be more appropriate
79
What is EVAR?
Endovascular aneurysm repair A minimally invasive technique that utilises endovascular iliofemoral access to deploy an aortic graft.
80
Outline the rules of driving with an AAA?
Patients must… - Inform the DVLA if they have an aneurysm above 6cm - Stop driving if it is above 6.5cm - Stricter rules apply to drivers of heavy vehicles (e.g., bus or lorry drivers)
81
What are the complications of an AAA?
Rupture Retroperitoneal leak Embolisation Aortoduodenal fistula
82
What increases the risk of AAA rupture?
Risk increases exponentially with the diameter of the aneurysm - 5% for 5cm and 40% for 8cm aneurysm Smoking, hypertension, female gender
83
How does an AAA rupture present?
Abdominal pain Back pain Syncope Loss of conciousness Vomiting Haemodynamically compromised Pulsation abdominal mass and tenderness (Classic triad - flank/back pain, hypotension, pulsation abdominal mass)
84
Whats the management for a ruptured AAA?
High flow oxygen, IV access, bloods (FBC, U&E, clotting, crossmatch) Be carefully treating shock/permissive hypotension - just keep bp so that pt is cerebrating If pt is unstable - immediate open surgical repair If pt is stable - CT angiogram to determine whether the aneurysm is suitable for endovascular repair
85
What is permissive hypotension?
the strategy of aiming for a lower than normal blood pressure when performing fluid resuscitation. The theory is that increasing the blood pressure may increase blood loss. This is done during management for ruptured AAA
86
What is angiodysplasia?
the presence of an arteriovenous malformation (AVM) located within the submucosa. An AVM is an abnormal connection between an artery and vein. This causes painless bleeding with no other significant clinical features Often occurs with diverticular disease
87
What are the 2 watershed areas of the Colon?
splenic flexure (Griffiths point) and rectosigmoid junction (Sudek's point) These are the regions most prone to ischaemia due to them being where arterial blood supply changes from one major vessel to the next
88
What are the differences between ischaemic colitis and mesenteric ischaemia?
Ischaemic colitis - typically large bowel, multi factorial, transient, less severe symptoms, bloody diarrhoa, thumbprinting, conservative management Mesenteric ischaemia - small bowe, usually due to embolism, sudden onset/severe symptoms, urgent surgery needed, high mortality

GI AND SURGERY (31 decks)

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