2- aortic disease: aneurysm & dissection

Question 1

what is an aneurysm?

Answer 1

a permanent, localised dilatation of an artery of more than 50% of the normal arterial diameter (i.e. 50% increase in diameter compared with non dilated adjacent vessel)

Question 2

what is normal aortic diameter?

Answer 2

1.2 - 2 cm

Question 3

what is a true aneurysm?

Answer 3

where all the 3 layers of the artery are involved

Question 4

what is a false aneurysm?

Answer 4

where there is a defect in the wall of the artery and it is the surrounding structures (skin, fat, fascia) that keep the aneurysm restrained

Question 5

what is the pathogenesis of abdominal aortic aneurysm?

Answer 5

• related to medial degeneration (tunica media degeneration)
• abnormal regulation of elastin & collagen proteins in the aortic wall by enzymatic agents such as metallo-proteinases not working properly causing a disruption →aneurysmal dilation (abnormal widening & bulging) →increase in aortic wall stress (more pressure & stretching)
• this continues and makes progressive aneurysmal dilation (process continues to worsen over time)

Question 6

does atherosclerosis related to aneurysmal formation?

Answer 6

no, not directly related - just an incidental finding

Question 7

what does abdominal aortic aneurysm present like?

Answer 7

• 75% of all are asymptomatic until rupture occurs
• 35% are symptomatic
• with sudden onset of abdominal & back pain and/or collapse

*often identified on imaging for other pathology

Question 8

what are ultrasound limitations?

Answer 8

only gives size - not moving up or show if just about to rupture

Question 9

what happens in CT angiography?

Answer 9

inject contrast and wait for contrast to hit arteries, you can then CT all the way down →allows us to see shape, size, what vessels involved, allows you to plan treatment

• IV contrast
• scan when contrast is in arterial system
• aneurysm morphology

Question 10

what are most ruptured aneurysms still contained in?

Answer 10

the retroperitoneum

Question 11

when is it recommended to repair a asymptomatic abdominal aortic aneurysm?

Answer 11

when it reaches 5.5 cm AP (anteroposterior) diameter

Question 12

what is criteria for aneurysm intervention?

Answer 12

• reaches 5.5 cm
• undergoes rapid expansion >1cm per year
• when AAA is symptomatic
  
  • rupture = if AAA bursts then life threatening emergency
  • thrashing = unstable or rapidly changing characteristics of AAA
  • pain

Question 13

what is elective aneurysm repair?

Answer 13

scheduled intervention for an abdominal aortic aneurysm (AAA) that is performed in a non-emergency setting

= it’s a prophylactic operation to reduce the risk of rupture balanced against risk of procedure

Question 14

what is emergency aneurysm repair?

Answer 14

therapeutic procedure balancing expectation for death against risk of procedure

Question 15

what is therapeutic procedure?

Answer 15

aimed at improving or treating a medical condition

Question 16

what is prophylactic procedure?

Answer 16

aimed at preventing medical condition

Question 17

what is EVAR?

Answer 17

endovascular aneurysm repair
= type of repair within blood vessel using minimally invasive techniques, via percutaneous access in groin with the stent inserted up through the common femoral artery

• stent-graft reinforces weakened or bulging area of aorta

Question 18

what are positives & negatives of EVAR?

Answer 18

positives = less mortality risk (far safer in complex aneurysms), much faster recovery

negatives = not possible in 25% of patients, needs on going follow up, may need further investigations

Question 19

what is open repair?

Answer 19

type of repair of aortic aneurysm through direct surgical intervention where weakened/bulging area assessed and repaired through direct surgical intervention, sewing graft to replace removed section of aorta

Question 20

what are positives and negatives of open repair?

Answer 20

positives = possible in just about everyone, rare further investigations, known to be effective for life

negatives = greater mortality risk, much slower recovery

Question 21

what assessments should be carried out to assess fitness for AAA intervention?

Answer 21

• cardiac assessment - echo/ejection fraction
• respiratory assessment - PFT
• cardiopulmonary exercise test - CPX testing
• renal assesment - U&Es
• vascular assessment - peripheral pulses/ABPI
• anaesthetic assessment
• EBT - end of bed or eyeball test

Question 22

what is some criteria of the aorta & vessels to be able to do an EVAR?

Answer 22

Aorta above AAA needs to be of correct morphology (size/shape) to land the stent above the AAA and the iliac arteries need to be disease free to be able to insert the device up to the AAA

= this needs imaging & contrast to check

Question 23

how many elective AAA can be treated with EVAR?

Answer 23

60-70% of elective AAA can be treated with EVAR

*saying that most scheduled aneurysm repairs can be treated with EVAR

Question 24

what is the outcome of a ruptured AAA?

Answer 24

• 50 - 75% will of patients not make it to hospital
• Most ruptured AAA are retroperitoneal, contained rupture
• Free intra-peritoneal rupture is rapidly fatal
• 50% operative mortality

Question 25

what is operative mortality for a) elective open AAA? b) elective EVAR?

Answer 25

a) 3-4% b) 1-2%

Question 26

what are complications for open repair?

Answer 26

- MI, CVA - pneumonia, wound infection, UTI, graft infection - DVT /PE - renal failure - dialysis may be required - Mesenteric ischaemia – may require bowel resection - Lower Limb Ischaemia + ‘Trash’ foot - Erectile dysfunction - Death

Question 27

what are complications of EVAR?

Answer 27

- Stent misplacement – covering the renal arteries, internal iliac arteries - Endoleak (this is defined a blood flow out with the stent in the aneurysm sac) - Stent migration and stent dislocation (the stents are modular and inserted into one another and over time they may dislocate from one another) - All EVAR require lifelong follow up (~20% of EVAR patients will require further intervention over their lifetime)

Question 28

what is the screening programme for aneurysms?

Answer 28

it aims to offer screening to all males >65 years with ultrasound scan (suggests reducing risk of death by 50%)

Question 29

what is aortic dissection?

Answer 29

dissection is tear - so it's an aortic tear (it's a distinct separate thing from aortic aneurysm but a dissected aorta may become aneurysmal)

Question 30

what is acute aortic syndrome?

Answer 30

group of series & potentially life-threatening conditions affecting aorta

Question 31

what are types of acute aortic syndrome?

Answer 31

- penetrating aortic ulcer = ulcer or lesion that penetrates through inner layers of aortic wall - intramural haematoma = collection of blood within the layers of aortic wall without a clear tear or dissection - aortic dissection = condition where there is a tear in inner layers of the aorta, allowing blood to flow between the layers, potentially causing layers to separate

Question 32

what do all the types of acute aortic syndrome have in common?

Answer 32

- all have disruption to tunica media layer - all have bleeding between the layers - all have transmural bleeding which is bleeding that extends through all layers potentially leading to rupture, outwith adventitia

Question 33

why is it tricky to deal with acute aortic syndrome?

Answer 33

because since all types have disruption to tunica media it's tricky to fix - think like toilet paper in a packet (inside cardboard ring is intima, paper itself is media and outer plastic is adventitia), the paper gets all soggy and hard to fix

Question 34

what are some factors associated with acute aortic syndrome?

Answer 34

- Family history - specific Gene mutations (fibrillin-1, transforming growth factor β1 etc) can affect structure & function of aorta - Connective Tissue Disorders, this can impact integrity of aorta - Ehlers Danlos, Marfans, Loeys dietz - Trauma including iatrogenic

Question 35

what happens in formation of aortic dissection?

Answer 35

cystic medial necrosis & medial degeneration →tear intimal layers →blood propagates within medial layer creating separation of layers →creates a flap; true lumen & false lumen

Question 36

where can the tear (aortic dissection) propagate? (spread)

Answer 36

centrally: aortic arch & it's branches, aortic valve, coronary arteries distally: mesenteric/renal arteries, iliac arteries down the limb

Question 37

how do you classify aortic dissection?

Answer 37

Stanford guide Type A = involves ascending aorta & arch, cardiothoracic emergency Type B = involves descending thoracic aorta (distal to left subclavian), vascular surgery

Question 38

how do people present with aortic dissection?

Answer 38

excruciating chest or interscapular pain (also back pain, and sometimes abdominal pain)

Question 39

what can propagation of dissection flap lead to?

Answer 39

- if involves valve →disrupted function →Acute aortic valve regurgitation - if affects coronary arteries →Myocardial infarction - if flap extends into pericardial sac →Cardiac tamponade - if involves blood vessels to brain →Stroke - if spread to vessels of upper limb →Upper limb ischaemia - Lower ischaemia - if involves blood vessels supplying intestine →Mesenteric ischaemia - if spread to spinal cord →Spinal ischaemia (paraplegia)

Question 40

what does CT angiogram of aortic dissection allow?

Answer 40

would be from aortic arch to femorals - Delineates (portrays precisely) anatomy - Delineates perfusion to end organs - Allows surgical planning (if appropriate)

Question 41

what is the aim of treatment of aortic dissection?

Answer 41

- prevent progression of dissection - prevent rupture - maintain or restore perfusion to end organs *you want to lower blood pressure & operate if needed

Question 42

what intervention do you want to do for acute phase aortic dissection?

Answer 42

acute phase < 2 weeks = aim to reduce flow in false lumen thereby decreasing diameter expansion of dissection - false lumen remodelling - complicated type B dissection (high risk, tissues like soggy paper)

Question 43

what intervention do you want to do for sub acute phase aortic dissection?

Answer 43

sub acute = 2 weeks to 90 days (tissues more robust) - false lumen modelling - reduce aortic related complications (aneurysms etc) *jury's still out on whether to operate

Question 44

what are complications of intervention?

Answer 44

- 30 day mortality up to 30% - 40% - Stroke – up to 10% - Spinal cord ischaemia – 2% - Retrograde Type A dissection - extension of dissection backward into ascending aorta