Diseases of the Thoracic Aorta

Question 1

What are the three layers of the aorta?

Answer 1

Tunica intima, tunica media, tunica adventitia.

Question 2

What is the tunica intima composed of?

Answer 2

Endothelial cells, sub endothelial layer - collagen and elastin fibres. Separated from tunica media internal elastic membrane.

Question 3

What is the tunica media composed of?

Answer 3

Smooth muscle cells which secrete elastin in the form of sheets or lamellae.

Question 4

What is the tunica adventitia composed of?

Answer 4

Thin connective tissue layer. Collagen fibres and elastin fibres (not llamellae). The collagen in the adventitia prevents elastic arteries from stretching beyond their physiological limits during systole.

Question 5

When will atherosclerosis start?

Answer 5

Can begin in early childhood.

Question 6

What are the risk factors for atherosclerosis?

Answer 6

Hypertension, hypercholesterolaemia, smoking, diabetes, family history, male (relative protection in females until menopause).

Question 7

What are some things atherosclerosis in the aorta can cause?

Answer 7

Stroke, MI, aneurysm

Question 8

What is an aneurysm?

Answer 8

A localised enlargement of an artery caused by weakening of the vessel wall.

Question 9

What is a true aneurysm?

Answer 9

Cause by weakness and dilation of all three layers of the wall. It is associated with hypertension, atherosclerosis, smoking and collagen abnormalities (Marfans, cystic medial necrosis), trauma, infection (mycotic/syphillis).

Question 10

What is a false aneurysm?

Answer 10

Rupture of the wall of aorta with the haematoma wither contained by the thin adventitial layer or by the surrounding soft tissue ???

Question 11

What is an aortic dissection?

Answer 11

Tear in inner wall of aorta, blood forces walls apart. Can be acute - medical/surgical emergency or chronic (smaller, healing themselves).

Question 12

Why is an arch aneurysm really dangerous?

Answer 12

Thats where the branches come off.

Question 13

What are some different types of aortic aneurysm (classified by site)?

Answer 13

Ascending aorta aneurysm, aortic arch aneurysm, descending aorta aneurysm, abdominal aorta aneurysm.

Question 14

What are some signs and symptoms of thoracic aneurysms?

Answer 14

Asymptomatic or
based on location of aneurysm - SoB or even heart failure (AR), dysphagia and hoarseness (ascending aorta, chronic), sharp chest pain radiating to back (b/w shoulder blades) - possible dissection, pulsatile mass, hypotension.

Question 15

What aetiological factors may contribute to aorta dissection?

Answer 15

Hypertension, athersclerosis, trauma, Marfans.

Question 16

Histologically what would an aortic dissection look like?

Answer 16

Cystic medial necrosis, false lumen can progress in an antegrade (down into the distal aorta) or retrograde (back into the ascending aorta).
May occlude branches (e.g. mesenteric, carotid, renal and spinal).

Question 17

What are the two classifications of aortic dissections?

Answer 17

Stanford and DeBakey.

Question 18

Describe Stanford classification.

Answer 18

Type A - all dissections involving the ascending aorta, regardless of the site of origin.
Type B - all dissections not involving the ascending aorta.

Question 19

Describe the DeBakey classification?

Answer 19

Stpe I - originates in the ascending aorta, propagares at least ti the aortic arch and often beyond it distally.
Type II - originates in t

Question 20

How might people present with an aortic dissection by showing neurological symptoms?

Answer 20

Dissection has caused occlusion of the carotid.

Question 21

How might an aortic dissection rupture?

Answer 21

Back into the lumen or externally into the pericardium (tamponade) or mediastinum.

Question 22

What might dilation of ascending aorta cause?

Answer 22

Patients may present in acute heart failure, if tear in heart valves causing acute aortic regurgitation.

Question 23

What are the symptoms of aortic dissection?

Answer 23

Tearing, severe chest pain (radiating to back)
Collapse (tamponade, acute AR, external rupture)
Beware inferior ST elevation
(50% mortality pre-hospital).

Question 24

What signs might you find on examination of aortic dissection?

Answer 24

Reduced or absent peripheral pulses (BP mismatch between sides)
Hypotension/hypertension
Soft early diastolic murmur (AR)
Pulmonary oedema
CXR usually shows widened mediastinum
Diagnosis can be confirmed by echocardiogram or CT.

Question 25

How do you treat type A (ascending aorta) aortic dissection?

Answer 25

Surgery.

Question 26

How do you treat type B (descending aorta) aortic dissection?

Answer 26

Meticulous BP control.
Sodium nitroprusside plus beta blocker.
Might also use GTN with an aim to keep BP stable.
Can be treated without surgery.

If impaired renal function, may give EVAR.

Question 27

What might cause inflammation of the thoracic aorta?

Answer 27

Takayasu’s Artertitis.

Question 28

What might cause infection of the thoracic aorta?

Answer 28

Syphyllis.

Question 29

What is Takayasu’s Arteritis? And how is it treated?

Answer 29

Rare. 
Granulomatous vasculitis. 
Females>males. 
Aorta and main branches. 
Stenosis, thrombosis, aneurysms, renal artery stenosis, neurological sx. 
Treated with steroids and surgery.

Question 30

What is syphilis caused by?

Answer 30

STD - treponema pallidum.

Antibiotics prevent late stages.

Question 31

How does syphilis present?

Answer 31

Primary - chancre, secondary - massive sores.

Tertiary - without treatment 1/3rd develop 1 of 3 types - late neuro-syphilis, gummatous syphilis, cardiac syphilis (10-30yrs post infection).

Question 32

What can cardiac syphilis cause?

Answer 32

Syphilitic aortitis - aneurysm.

Aortic regurgitation.

Question 33

What might congenital conditions might cause an aortic aneurysm?

Answer 33

Bicuspid aortic valve, Marfans, coarctation.

Question 34

What is the most common congenital abnormality?

Answer 34

Bicuspid aortic valve. 1-2% prevalence.

Question 35

What are people with bicuspid aortic valves prone to?

Answer 35

Prone to stenosis with or without regurgitation. Associated with coarctation. Abnormal aorta (reduced tensile strength), prone to aneurysm/dissection.

Question 36

How would you monitor someone with bicuspid aortic valve?

Answer 36

Monitor with echo/MRI.

Question 37

What is aortic coarctation?

Answer 37

Aortic narrowing normally close to where the ductus arterioles inserts (ligament arteriosum).

Question 38

What are the three types of coarctation?

Answer 38

Pre-ductal (5% turner’s) can be life threatening if severe narrowing.
Ductal
Post-ductal - most common in adults - hypertension in upper extremities, weak pulses in lower limbs.

Question 39

What are the signs of coarctation?

Answer 39

Cold legs, poor leg pulses, if before left subclavian artery (radial - radial and right radial femoral delay).
If after left subclavian artery - no radial/radial delay, right and left radio-femoral delay.

Question 40

What are the symptoms of coarctation?

Answer 40

Infancy (severe) - heart failure, failure to thrive.

Later in life - hypertension.

Question 41

How might the coarctation show up on an Xray?

Answer 41

Rib notching.

Question 42

What does having Marfan’s syndrome put you at risk of?

Answer 42

Aneurysm and dissection. Aortic/mitral valve

Question 43

What does having Marfan’s syndrome put you at risk of (in terms of CV disease)?

Answer 43

Aneurysm and dissection. Aortic/mitral valve prolapse/regurgitation.

Question 44

How can Marfan’s impact on other systems in the body?

Answer 44

Impact on skeletal system, eyes (cataract, lens dislocation), lungs (pneumothorax).

Question 45

What mutation does Marfan’s stem from?

Answer 45

Fibrillin 1 gene - causes connective tissue weakness.