Abdominal aortic aneurysm

Question 1

Average lifetime aortic blood flow

Answer 1

200 million litres

Question 2

Layers of arterial wall

Answer 2

Tunica intima: covered by endothelium

Tunica media: thick collagen

Tunica adevntita: extrnal coverings containing vasa vasorum

Question 3

Windkessel function

Answer 3

Refers to the secondary pump quality of the aortic

Elastic nature provides pump force during diastole
–> helps to perfuse coronaries

Question 4

Average aortic expansion

Answer 4

Men: 0.9mm per DECADE

Women: 0.7mm per DECADE

Question 5

Symptoms of aortic disease

Answer 5

Acute deep, aching or throbbing chest or abdominal pain that can spread to the back, buttocks, groin or legs, suggestive of AD or other AAS, and best described as ‘feeling of rupture’

Cough, shortness of breath, or difficult or painful swallowing in large TAAs.

Constant or intermittent abdominal pain or discomfort, a pulsating feeling in the abdomen, or feeling of fullnessafter minimal food intake in large AAAs.

Stroke, transient ischaemic attack, or claudication secondary to aortic atherosclerosis.

Hoarseness due to left laryngeal nerve palsy in rapidly progressing lesions.

Question 6

Ideal place to measure diameter of aorta

Answer 6

Measure diameter perpendicular to flow

Measure at set anatomical points

Question 7

When in cardiac cycle to measure aortic diameter

Answer 7

Discussion to be had

Diastolic measurements are the most reproducible

Question 8

Inter and itnra variability in measurement of diameter on CT

Answer 8

Inter assessor variability ~ 5mm

Intra assessor variability ~3mm

Generally changes <5mm unlikely to be significant

Question 9

Ultrasound measurement of aortic diameter

Answer 9

Tend to under report size by 1-3mm

Measured in AP direction

Question 10

Use of PET CT

Answer 10

18F-fluorodeoxyglucose (FDG), which is taken up with high affinity by hypermetabolic cells (e.g. inflammatory
cells), and can be used to detect vascular inflammation in large vessels.

The advantages of PET may be combined with CT imaging with good resolution.

inflammatory vascular disease (e.g. Takayasu arteritis,GCA), to detect endovascular graft infection,
and to track inflammatory activity over a given period of
treatment

Question 11

Disadvantages of MRA

Answer 11

Cannot evaluate calcification which is important for evaluating landing zones of a graft

Availability

Difficulty in patient monitoring during scan

Time taken to perform scan

Gadolinium causes nephrogenic systemic fibrosis

Question 12

Measuring aortic stiffness

Answer 12

Carotid -femoral pulse wave velocity

Fast velocity = stiffer aorta

> 10m/s = stiff aorta

Predictor of CV events and poor otucome

Question 13

Effect of smoking on aneurysm expansion

Answer 13

Quicker aneurysm expansion

Smoking status associated with expansion rate of 0.4mm / YEAR

Question 14

TEVAR landing zone

Answer 14

Diameter <40mm

Length >20mm

Question 15

CT angiogram pre TEVAR

Answer 15

<3mm slices
From supra-aortic vessels down to femoral arteries

Asses landing zones

Asses relationship to side branches

Evaluate femoral access

Question 16

Stent sizing in dissection vs aneurysm TEVAR

Answer 16

Dissection:

• Land at site of false lumen to occlude lumen and de-pressurise false lumen
• Do not over-size in diameter

Aneurysm

• Over-size in diameter by 10-15%
• Landing zone needs to be clear of aneurysmal disease

Question 17

Definition of proximal aortic neck

Answer 17

Segment of aorta below renal arteries up to the most cephalic section of aneurysm

Hostile neck
>60% angulation –> migration and endoleaks
<15mm –> difficult landing
>32mm in diameter means endovascular stent unlikely

Question 18

Features of good proximal aortic neck

Answer 18

<60% angulation

> 10-15mm in length

<32mm in diameter

Question 19

Why do you not cover both internal iliacs

Answer 19

Causes bilateral hypogastric artery occlusion

Leads to:

• Impotence
• Spinal cord ischaemia
• Visceral ischaemia
• Buttock caludication

Question 20

When to ligate inferior mesenteric artery (open)

Answer 20

Conditions for ligation:

• brisk back bleeding from IMA
• bilateral patent hypogastric arteries i.e. not occluding either internal iliac

If sluggish bleeding or occluding one of the iliac –> re-implant IMA

Question 21

Definition of acute thoracic aortic syndrome

Answer 21

Defined as emergency conditions with similar clinical characteristics involving the aorta

Essentially a breakdown of the intima and media:

• intramural thrombus
• penetrating atherosclerotic ulcer
• dissection
• rupture

Question 22

De Bakey classification

Answer 22

De Bakey = 1, 2 , 3

Classification of throacic aortic dissection

1: ascending and descending thoracic aorta
2: ascending thoracic aorta prior to innominate artery
3: descending thoracic artery at point of innominate artery

Question 23

Stanford classification

Answer 23

A or B

A: involved the ascending thoracic aorta +/- descending thoracic aorta

B: involves only the descending thoracic aorta

Question 24

Classification of aortic dissection

Answer 24

1 - 5

1: classic dissection. No communication between to lamina, true and false lumen exist
2: intramural haematoma
3: subtle dissection with bulging of arterial wall
4: penetrating atherosclerotic ulcer
5: traumatic / iatrogenic

Question 25

Recommendations for imaging of aorta (7)

Answer 25

1) It is recommended that diameters be measured at pre-specified anatomical landmarks, perpendicular to the longitudinal axis. IC
2) In the case of repetitive imaging of the aorta over time, to assess change in diameter, it is recommended that the imaging modality with the lowest iatrogenic risk be used. IC
3) In the case of repetitive imaging of the aorta over time to assess change in diameter, it is recommended that the same imaging modality be used, with a similar method of measurement. IC
4) It is recommended that all relevant aortic diameters and abnormalities be reported according to the aortic segmentation. IC
5) It is recommended that renal function, pregnancy, and history of allergy to contrast media be assessed, in order to select the optimal imaging modality of the aorta with minimal radiation exposure, except for emergency cases. IC
6) The risk of radiation exposure should be assessed, especially in younger adults and in those undergoing repetitive imaging. IIaB
7) Aortic diameters may be indexed to the body surface area, especially for the outliers in body size. IIbB

Question 26

Recommendations for thoracic endovascular repair (TEVAR) (4)

Answer 26

1) It is recommended that the indication for TEVAR or EVAR be decided on an individual basis, according to anatomy, pathology, comorbidity and anticipated durability, of any repair, using a multidisciplinary approach. IC
2) A sufficient proximal and distal landing zone of at least 2 cm is recommended for the safe deployment and durable fixation of TEVAR. IC
3) During stent graft placement, invasive blood pressure monitoring and control (either pharmacologically or by rapid pacing) is recommended. IC
4) Preventive cerebrospinal fluid (CSF) drainage should be considered in high-risk patients. IIaC

Question 27

Recommendations for surgical repair of thoracic aorta

Answer 27

Cerebrospinal fluid drainage is recommended in surgery of the thoraco-abdominal aorta, to reduce the risk of paraplegia. IB

Aortic valve repair, using the re-implantation technique or remodelling with aortic annuloplasty, is recommended in young patients with aortic root dilation and tricuspid aortic valves. IC

For repair of acute Type A AD, an open distal anastomotic technique avoiding aortic clamping (hemiarch/complete arch) is recommended. IC

In patients with connective tissue disordersd requiring aortic surgery, the replacement of aortic sinuses is indicated. IC

Selective antegrade cerebral perfusion should be considered in aortic arch surgery, to reduce the risk of stroke. IIaB

The axillary artery should be considered as first choice for cannulation for surgery of the aortic arch and in aortic dissection. IIaC

Left heart bypass should be considered during repair of the descending aorta or the thoraco-abdominal aorta, to ensure distal organ perfusion. IIaC