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Core Conditions - Vascular > Abdominal Aortic Aneurysm > Flashcards

Abdominal Aortic Aneurysm Flashcards

1
Q

What is the definition of an aneurysm?

A

an aneurysm is an artery that has a localised dilation

with a permanent diameter of at least 1.5x the expected diameter of that particular artery

an aneursym can be a true aneurysm or a false aneurysm

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2
Q

What is a true aneurysm?

Which arteries tend to be affected by this?

A

the wall of the artery forms the wall of the aneurysm

the arteries most frequently involved are:

  • abdominal aorta (most common)
  • iliac artery
  • popliteal artery
  • femoral artery
  • thoracic aorta (least common)
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3
Q

What is a false aneurysm (pseudoaneurysm)?

Which artery is most commonly affected?

A

other surrounding tissues form the wall of the aneurysm

this most commonly occurs in the femoral artery following puncture

if there is inadequate pressure applied to the puncture site, blood spills out and forms a haematoma

eventually the surrounding soft tissue will form the wall of the haematoma

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4
Q

What is the difference between a pseudoaneurysm and a true haematoma?

A

pseudoaneurysm:

  • there is still communication between the lumen of the artery and the fluid collection

true haematoma:

  • there is either no communication
  • or there is a one way “leakage” of fluid
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5
Q

What are the 2 different shapes of aneurysm?

A

fusiform:

  • the aneurysm is tapered at both ends (like a raindrop with 2 points)

sac-like:

  • the aneurysm is more rounded in shape
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6
Q

When inspecting an aneurysm, what characteristic should you feel for?

How is this different to nodes overlying an artery?

A

you should feel for the aneurysm being EXPANSILE

this means that it expands and contracts

nodes overlying arteries are PULSATILE

these means they do not expand and contract, but just transmit the pulse

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7
Q

What are the risk factors for aneurysmal disease?

What condition are these similar to?

A

the risk factors for aneurysmal disease are similar to those for atheromatous disease, despite the different pathology

  • hypertension
  • smoking
  • obesity
  • diabetes
  • sedentary lifestyle
  • high LDL levels
  • increasing age
  • family history
    • 10% of cases have a first-order relative also with the condition
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8
Q

What are specific aetiological factors for aneurysmal disease?

A
  • coarctation of the aorta
  • pregnancy (especially in the 3rd trimester)
  • Marfan syndrome (or other connective tissue disorders)
  • previous aortic surgery
  • trauma
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9
Q

Who is more commonly affected by aneurysms?

A
  • incidence increases with age
    • 5% of men over 60 have an aneurysm
  • aneurysms are 3-5 x more common in men than women
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10
Q

What are the common complications of local aneurysms?

A

Aneurysms themselves do not often constitute a primary problem

  • can cause local obstruction (e.g. of the IVC)
  • can cause impaired blood flow to the lower limbs

They are a risk factor for thrombosis and embolism

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11
Q

What is the main risk factor associated with aneurysms?

A

the tendency of aneurysms to dissect and rupture

an aortic aneurysm most commonly ruptures into the retroperitoneal space

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12
Q

How does repair of aneurysms differ before and after rupture?

A
  • elective repair of aneurysms before rupture is comparitively safe
  • repair of aneurysms after rupture has a very high mortality
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13
Q

How are aortic aneurysms usually detected?

A

They are usually asymptomatic and are identified incidentally

e.g. through examination, AXR, CT or USS

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14
Q

What is the mean age of presentation for an aortic aneurysm?

How are they usually picked up?

A

65

around 65% of aneurysms are sufficiently calcified to be picked up on abdominal X-ray

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15
Q
A
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16
Q

What method is used to stage aneurysms?

A

ultrasound scan

it is accurate at assessing the site of the aneurysm and easy to follow up cases to assess development

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17
Q

What are the benefits of using CT to investigate aneurysms?

Why is CT not used to assess and follow up aneurysms?

A
  • more accurate than USS
  • useful at looking at surrounding structures (e.g. to see if there is any compression

it is very expensive so only tends to be used pre-operative assessment

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18
Q

What is risk of dissection of an aneurysm correlated with?

A

risk of dissection (bursting) increases with the diameter of the aneurysm

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19
Q

What is the main concern about thrombus formation and aneurysms?

A

aneurysm is a source of thrombus formation, which can emobilise to the lower limbs

very rarely does the site of the aneurysm become completely occluded by thrombus

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20
Q

What do NICE guidelines state about which aneurysms need surgical intervention?

A

an aortic aneurysm of greater than 5.5cm in diameter should be treated

below this size, the risk of dissection (bursting) is outweighed by the risk of surgery

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21
Q

What is the annual risk of rupture of aortic aneurysms with a diameter of 5.5, 6.5 and 7cm?

A
  • at 5.5cm annual risk of rupture is 25%
  • at 6.5cm annual risk of rupture is 35%
  • at >7cm annual risk of rupture is 75%
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22
Q

Other than diameter >5.5cm what are other indications for treatment of aneurysms?

A
  • symptomatic aneurysms of smaller size are sometimes operated on
  • pain is thought to be a risk factor for rupture
  • thrombo-embolus is an indication for surgery
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23
Q

What is the surgical procedure that is performed to treat an aortic aneurysm?

A

open laparotomy

the affected segment of aorta is clamped and replaced by a prosthetic segment (usually a Dacron graft)

(or the affected artery segment may be bypassed )

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24
Q

What are the potential complications following open laparotomy to treat an aortic aneurysm?

A

graft failure is rare and complications are also rare

  • kidney problems
  • paraplegia
  • ischaemic colitis
  • fistula formation with the small bowel

infection is also very rare

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25
Q

How does mortality change in elective aneurysm, symptomatic aneurysm and ruptured aneurysm surgery?

A
  • 5-8% in elective asymptomatic AAA
  • 10-20% in symptomatic emergency AAA
  • 50% in ruptured AAA

long-term survival for most patients with AAA is almost identical to the general population

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26
Q

What is an alternative surgical option to open laparotomy for treating aortic aneurysm?

A

Endoluminal surgery - Endovascular aneurysm repair (EVAR)

  • an aortic graft is inserted through the femoral artery and passed up into the abdominal aorta
  • this method is preferred due to its lower mortality
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27
Q

Why is endovascular aneurysm repair (EVAR) not performed in all patients?

A

many patients are not suitable for this method

there must be at least 2.5cm of normal aorta between the aneurysm and the renal arteries to securely fix the graft in place

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28
Q

What are the benefits and drawbacks of performing EVAR compared to open laparotomy to fix an aortic aneurysm?

A

benefits:

  • lower mortality of 1.2%
  • risks of procedure are much lower

drawbacks:

  • higher risks of complications with the graft
  • graft can fail or can be moved, allowing blood to refill the aneurysm
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29
Q

How does death rate change with age if an aortic aneurysm was to rupture?

A

death rate from rupture of an aortic aneurysm increases with age

  • age 55-59 - death rate is 12.5 per 100,000
  • age 80+ - death rate is 273 per 100,000
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30
Q

Of those with a ruptured aortic aneurysm, what % tend to survive?

A
  • >75% with a ruptured AA will die - usually before getting to hospital
  • of those that reach hospital, surgery has a 50% mortality rate
  • only around 10% of those with a ruptured AA will survive
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31
Q

What is meant by “rupture” when talking about aortic aneurysms?

A

rupture describes the wall of the aorta completely failing, and blood escaping into a body cavity (e.g. abdominal cavity)

this is different to dissection, although dissection often leads to rupture

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32
Q
A
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33
Q

What is meant by “dissection” when talking about an aortic aneurysm?

A

where blood escapes through the innermost layer of the wall of the aorta, and prises apart the media, creating a new lumen

this can be stable but also has a high risk of rupturing

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34
Q

What is meant by a “double-barreled aorta”?

A

an aorta with a second vascular lumen formed in the media of the aortic wall, which connects the proximal and distal intimal tears in an aorta with a dissecting aneurysm

this occurs when the new lumen is absorbed back into the main lumen

35
Q

What happens if an aortic aneurysm dissection tracks back?

A

the dissection is sometimes able to track back all the way to the pericardium and cause haemopericardium

36
Q

How urgent is aortic aneurysm dissection and why?

A

it is a medical emergency and needs to be treated ASAP

if blood manages to escape through all the layers of the aortic wall, then rupture is the result

37
Q

What is the difference between an acute and chronic aortic dissection?

A

Acute:

  • the intimal tear is diagnosed at 14 days or less

Chronic:

  • the intimal tear is diagnosed after 14 days or more
38
Q

What is the difference between an anterograde or retrograde dissection?

A

aortic dissections from the initial intimal tear can progress distally, proximally, or in both directions from the point or origin

anterograde dissections:

  • propagate towards the iliac arteries

retrograde dissections:

  • propagate towards the aortic valve (at the root of the aorta)
39
Q

What are additional risks associated with retrograde aortic aneurysm dissections?

A

they can result in:

  • prolapse of the aortic valve
  • bleeding into the pericardium
  • cardiac tamponade
40
Q

How is the Stanford classification used to classify aortic dissections?

A

Type A:

  • involves the ascending aorta
  • may propagate to the aortic arch and descending aorta
  • tear can originate anywhere along this path

Type B:

  • dissections affect the descending aorta ONLY
  • do not involve the ascending aorta
41
Q

How is the DeBakey classification used to group aortic dissections anatomically?

A

Type I:

  • originates in the ascending aorta and propagates at least to the aortic arch

Type II:

  • confined to the ascending aorta

Type III:

  • originates distal to the subclavian artery in the descending aorta
42
Q

How can a type III DeBakey aortic dissection be further classified?

A

Type IIIa:

  • originates distal to the subclavian artery in descending aorta
  • extends distally to the diaphragm

Type IIIb:

  • originates distally to the subclavian artery in descending aorta
  • extends beyond the diaphragm into the abdominal aorta
43
Q

How does an aortic dissection present with pain?

How does the pain differ in a dissection of the ascending aorta/descending aorta?

A

there is sudden onset, severe pain

it is often described as tearing and usually radiates to the back

in the ascending aorta, pain is often in the chest

in the descending aorta, pain is often in the back

44
Q

What are the other symptoms, other than pain, that are associated with aortic dissection?

A
  • collapse due to hypotension
  • expansile (not pulsatile) mass in the abdomen
  • shock
  • hypotension
  • tachycardia
  • profound anaemia
  • sudden death
45
Q

What are the most common clinical signs of aortic dissection?

A

the most common clinical signs include:

  • tachycardia
  • hypotension
  • new aortic regurgitation murmur
  • signs of end-organ hypoperfusion
46
Q

What are signs of end-organ hypoperfusion that may be present as a clinical sign of aortic dissection?

A
  • reduced urine output
  • paraplegia
  • lower limb ischaemia
  • abdominal pain secondary to ischaemia
  • deterorating conscious level
47
Q

Why is hypotension a clinical sign of aortic dissection?

A

it occurs secondary to hypovolaemia from blood loss into the dissection

or cardiogenic from severe aortic regurgitation or pericardial tamponade

48
Q

What is the characteristic presentation of aortic dissection?

A

a tearing chest pain, classically radiating through to the back

the diagnosis is often challenging and may be a more subtle presentation

49
Q

What are the differential diagnoses for aortic dissection?

A
  • myocardial infarction
  • pulmonary embolism
  • pericarditis
  • musculoskeletal back pain
50
Q

How can presentation of aortic dissection and MI be distinguished?

A

MI presents with a classically crushing and central chest pain

there are signs of ischaemia on ECG

and / or raised serum troponin levels

51
Q

How can aortic dissection be clinically distinguished with pulmonary embolism?

A
  • dyspnoea is a prominent feature
  • ABG will demonstrate hypoxia
  • this is confirmed with CTPA (pulmonary angiogram) or V/Q scan
52
Q

How can aortic dissection be distinguished clinically from pericarditis?

A

pericarditis classically presents with pleuritic chest pain

an ECG will show diffuse ST elevation

as well as potential pericardial rub on auscultation

53
Q

How can aortic dissection be distinguished from musculoskeletal back pain?

A

the patient will not present with systemic signs of shock

and will be tender to palpation of the chest wall or paraspinal muscles

54
Q

What are your initial investigations for aortic dissection?

A

diagnosis is usually clinical, and needs to be made quickly

  • baseline blood tests with a crossmatch of at least 4 units
    • FBC, U&Es, LFTs, troponin, coagulation
  • arterial blood gas
  • ECG to exclude any cardiac pathology
55
Q

What is the imaging of choice that is recommended to diagnose aortic dissection?

A

CT angiogram

this allows for classification, establishing the anatomy of the dissection and assists surgical planning

56
Q

What is the initial management for aortic dissection, regardless of what type it is?

A

urgent initial assessment is required, as for any other critically ill surgical patient

  • start high flow oxygen
  • gain IV access with 2x large bore cannulas
  • fluid resuscitation (should be done cautiously)
57
Q

What is the target pressure for fluid resuscitation in a rupture and an uncomplicated dissection?

A

Rupture:

  • target pressure sufficient for cerebral perfusion only

Uncomplicated dissection:

  • target systolic pressure should be kept below 110mmHg
58
Q

What is the main difference in the initial management of Type A and Type B Stanford dissections?

A

Type A:

  • should be managed surgically in the first instance
  • carry a worse prognosis than Type B

Type B:

  • any uncomplicated Type B dissections can usually be managed medically
59
Q

What treatment / imaging do all patients who have had an aortic dissection require in the future?

A
  • all patients require lifelong antihypertensive therapy & surveillance imaging
  • imaging occurs at 1, 3 and 12 months post-discharge
  • then further scans at 6-12 month intervals thereafter depending on the size of the aorta
60
Q

What surgical technique is used to treat Type A aortic dissections?

A

Dacron graft

  • the ascending aorta (with or without arch) is removed & replaced with a synthetic graft
  • if dissection has damaged the suspensory apparatus of the aortic valve, this will also require repair
61
Q

What is the first line medical treatment for management of Type B dissections?

What is the aim of this therapy?

A
  • management of hypertension with IV beta blockers (labetalol)
  • calcium channel blockers are used as second line therapy

the aim is to rapidly lower systolic pressure, pulse pressure and pulse rate

this will minimise stress of the dissection and limit further propagation

62
Q

Why is medical management the gold standard for treatment of Type B dissections?

A

in the acute setting, endovascular repair is not recommended due to the risk of retrograde dissection

63
Q

When is surgical intervention of Type B dissections warranted?

A

only in the presence of certain complications, such as:

  • rupture
  • renal, visceral or limb ischaemia
  • refectory pain
  • uncontrollable hypertension
64
Q

What happens if a Type B dissection develops to become chronic?

What is the treatment then?

A

if it is chronic, there is continued leakage into the dissection, even if a stent has been placed

the most common complication of chronic disease is formation of an aneurysm

then endovascular repair will offer a better survival chance

65
Q

What are the possible complications of aortic dissection?

A

complications depend on the site and spread of the dissection into the aortic branches, damaging end organs

  • aortic rupture
  • aortic regurgitation
  • myocardial ischaemia
    • secondary to coronary artery dissection
  • cardiac tamponade
  • stroke or paraplegia
    • ​secondary to cerebral artery or spinal artery involvement
66
Q

Which segment of the aorta is usually implicated in an abdominal aortic aneurysm?

A

80% of cases found in the infrarenal segment of the aorta

these most commonly occur below the level of the renal artery

67
Q

How is the pain described in an abdominal aortic aneurysm?

What can it be confused with?

A
  • rapid expansion or rupture causes epigastric pain that radiates to the back
  • pain may be present in the groin, iliac fossae and testicles
  • pain can be constant or intermittent

DO NOT DISMISS AS RENAL COLIC

68
Q

How does a thoracic aortic aneurysm tend to present?

A
  • asymmetrical brachial / radial / carotid pulses if dissection involves aortic arch
  • BP may be different in each arm
69
Q

What is the definition of an aneurysm?

What is the most common cause of a true aneurysm?

A

permanent dilation of the vessel wall

the fact that it is permanent implies that the vessel wall itself is altered in some way

atheromatous degeneration is the most common cause of true aneurysm

70
Q

What are the risk factors for aneurysm?

A

as the most common cause is atheromatous degeneration, the risk factors are the same as for CHD

  • smoking
  • family history
  • diabetes
  • hypertension
  • advancing age
  • hyperlipidaemia
71
Q

What is thought to be the pathology underlying an aneurysm?

A
  • ischaemia of the aortic media where there is an atherosclerotic plaque
  • this is a result of macrophage enzymes (released when macrophages are activated) that break down elastic fibres (collagen & elastin)
  • ischaemia results in loss of the normal elastic nature of the media, allowing it to expand
72
Q

What is thought to explain the familial aspect of aneurysms?

A

there is evidence that various genetic variants of collagen are more susceptible to breakdown by macrophages

73
Q

What is Marfan syndrome?

What mutation causes it?

A

a connective tissue disorder that is usually inherited in an autosomal dominant manner

it is caused by mutations in the FBN1 gene, which provides instructions for making the fibrillin-1 protein

74
Q

How many people and what gender are affected by Marfan syndrome?

A
  • very common affecting 1 in 5000 individuals
  • 25% of cases are due to a new mutation
  • males and females are equally affected
75
Q

What is tested for when screening family members for Marfan syndrome?

A

Fibrillin-1 gene mutations

These are seen in 80% of cases

76
Q

What are the most common clinical features of Marfan syndrome?

A
  • arachnodactyly
  • joint hypermobility
  • scoliosis (lateral curvature of the spine)
  • dislocation of the lens of the eye
  • high arched palate
  • chest deformity
  • patients are usually tall and thin, with long limbs
77
Q

What is arachnodactyly?

A

abnormally long and thin fingers in comparison to the palm

in Marfan syndrome, the fingers may be bent backwards at the MCP joint to 180 degrees

78
Q

How can Marfan syndrome predispose to aneurysms?

Which part of the aorta tends to be affected?

A
  • weakening of the media layer of the aorta, leading to dilatation
  • dilatation typically occurs in the ascending aorta
  • there may also be heart valve defects (e.g. aortic regurgitation) which complicate the issue
  • the root of the aorta tends to be affected
79
Q

How can Marfan syndrome also lead to lung and dura disorders?

A

as well as fibrin defects, there are problems in the TGF-B (transforming-growth-factor-B)

this accumulates in the heart valves and blood vessels and alters their underlying structure, leading to complications

80
Q

What medical therapy is used in Marfan syndrome?

A

B-blockers

proven to reduce the rate and risk of dilatation of the aorta

81
Q

How is monitoring carried out in patients with Marfan syndrome?

A

monitoring of aortic dilatation through X-ray, Echo, MRI or CT

patients are usually followed up with yearly Echo to assess the size of the aorta

in some cases, elective replacement of the ascending aorta may be recommended to prevent dissection, but has a mortality of 5-10%

82
Q

What activities should patients with Marfan syndrome avoid?

A

endurance sport / activities

83
Q

What measures are in place to monitor pregnant women with Marfan syndrome?

When is caesarean section recommended?

A

both pregnancy and Marfan syndrome are risk factors for AA so the aorta is monitored by an Echo every 6 weeks

caesarean is considered when aortic root is >4cm

B-blocker therapy is safe to continue

84
Q

What is the overall prognosis like in Marfan syndrome?

A

generally good, although less than the general population

surgical interventions have increased average life expectancy by 13 years

Core Conditions - Vascular (7 decks)

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