Aortic disease

Question 1

Describe anatomy of thoracic aorta.

Answer 1

Thoracic aorta divided into 4 sections:
1. Aortic root - starts at the level of the aortic valve until the sinotubular junction.
2. Ascending aorta - starts at the level of the sinotubular junction and the origin of the indominate artery, which is also called the brachiocephalic artery.
3. Aortic arch - starts at the origin of the indominant artery until just after the left subclavian artery.
4. Descending thoracic aorta - starts just after the origin of the left subclavian artery and the diaphragm.

Question 2

Describe the layers of the aorta.

Answer 2

Tunica intima:
- Layer of endothelial cells
- Subendothelial layer – collagen and elastic fibres
- Separated from tunica media internal elastic membrane.

Tunica media:
- smooth muscle cells
- secrete elastin in the form of sheets, or lamellae

Tunica adventitia:
- Thin connective tissue layer
- Collagen fibres and elastic fibres (not lamellae)
- The collagen in the adventitia prevents elastic arteries from stretching beyond their physiological limits during systole

Question 3

Describe the risk factors for atherosclerosis

Answer 3

Risk factors of atherosclerosis: hypertension, hypercholesterolaemia,
smoking,
diabetes,
family history,
male>female.

Question 4

Describe what conditions atherosclerosis causes.

Answer 4

Atherosclerosis is the pathophysiology processes of: Myocardial infarction,
stroke,
peripheral vascular disease aneurysm

Question 5

Define Aneurysm

Answer 5

Aneurysm definition - localised enlargement of an artery caused by a weakening of the vessel wall.

Question 6

Describe the classifications of Aneurysm

Answer 6

False aneurysm - rupture of wall of aorta with the haematoma either contained by the thin adventitial layer or by the surrounding soft tissue. Aetiology: trauma, latrogenic, inflammation.

True aneurysm - Weakness and dilation of wall, involves all 3 layers. Associated with: hypertension, atherosclerosis, smoking, bicuspid aortic valve, collagen abnormalities, infection and trauma.

Question 7

Describe signs and symptoms of aneurysms

Answer 7

Asymptomatic
Based on the location of the aneurysm:
- Shortness of breath (associated aortic regurgitation)
- Dysphagia and hoarseness
- Back pain
- Symptoms of dissection - sharp chest pain radiating to back (between shoulder blades), hypotension
- Pulsatile mass

Question 8

Describe investigations for thoracic aneurysms.

Answer 8

CXR – widened mediastinum

Echocardiogram – assess aortic root size and aortic valve (limited views of distal ascending aorta and arch)

CT angiogram aorta – diagnostic

MRI aorta – diagnostic and follow-up

Other tests: TOE and invasive aortogram – rarely done

Question 9

Describe aortic dissection

Answer 9

Aortic dissection - caused by tear in the inner wall of aorta. Blood forces walls apart. Acute dissection is a surgical and medical emergency but they can also present as a chronic dissection.

Question 10

Aetiological factors of aortic dissection.

Answer 10

Aetiological factors:
- Hypertension
- Atherosclerosis
- Marfan’s syndrome
- Bicuspid aortic valve
- Trauma

Question 11

Describe the classification of thoracic aortic dissection.

Answer 11

The two most common classification systems of thoracic aortic dissection: Stanford and DeBakey.

In Stanford system aortic dissections are either classed as type A or type B. Type A: all dissections involving the ascending aorta, regardless of the site of origin. Type B: All dissections not involving the ascending aorta.

Question 12

Describe symptoms of aortic dissection.

Answer 12

Chest pain – severe, sharp, radiating to back (inter-scapular)

Collapse (tamponade, acute AR, external rupture)

Stroke (involvement of carotid arteries)

Question 13

Describe signs of aortic dissection.

Answer 13

• Reduced or absent peripheral pulses
• Hypertension or hypotension
• BP mismatch between sides
• Soft early diastolic murmur (aortic regurgitation)
• Pulmonary oedema
• Signs of CVA

Question 14

Investigation of aortic dissection.

Answer 14

ECG – might show ST elevation/ischaemia indicating coronary involvement

CXR - widened mediastinum

Transthoracic echocardiogram (TTE) – assess aortic root (limited views), aortic regurgitation? pericardial effusion ?

CT angiogram aorta - confirms diagnosis
~ 50% mortality pre-hospital

Question 15

Treatment for type A aortic dissection.

Answer 15

Type A
- Blood Pressure control: beta blocker, IVI nitrate, calcium channel blocker, IVI Sodium nitroprusside
- Emergency Surgery

Question 16

Treatment for type B aortic dissection.

Answer 16

Type B
- Blood pressure control: beta blocker, IVI nitrate, calcium channel blocker, IVI Sodium nitroprusside
- Percuraneous (endo-vascular) intervention

Question 17

What infection predisposes to thoracic aortic disease

Answer 17

Syphyllis

Question 18

What inflammatory condition predisposes to thoracic aortic disease

Answer 18

Takayasu’s Arteritis

Question 19

Describe Pathology of Takayasu’s Arteritis

Answer 19

Takayusu’s arteritis is a granulmatous vasculitis which affects the aorta and the main branches of the aorta. It can result in stenosis, aneurysm, thrombosis and it affects females more than males. Presentation depends on the arteries involved.

Question 20

Treatment of Takayasu’s Arteritis

Answer 20

Treatment includes steroids and immunosuppressive therapy, occasionally the patient might be referred for surgery or percutaneous intervention if there is organ ischaemia.

Question 21

Describe Syphillis Pathology and treatment

Answer 21

Syphilis - STD caused by treponema pallidum. Treatment with antibiotics prevent late stage complications.

Question 22

What conginetal conditions can predispose to thoracic aortic aneurysm.

Answer 22

• Bicuspid aortic valve, coarctation and marfan’s syndrome.

Question 23

Define Bicuspid aortic valve

Answer 23

Bicuspid aortic valve - normal aortic valve has three cusps, bicuspid aortic valve has two cusps. The valve has two cusps because two of the leaflets have fused.

Question 24

Describe characteristics of bicuspid aortic valve.

Answer 24

Most common congenital abnormality
1-2% prevalence
Prone to aortic valve stenosis +/- regurgitation
Associated with coarctation
Abnormal aorta (reduced tensile strength)
Prone to aneurysm/ dissection
Monitor with echo/ MRI

Question 25

Describe Coarctation

Answer 25

Aortic narrowing close to where
Ductus arteriosus inserts
(ligamentum arteriosum)

Question 26

Describe the 3 types of Coarctation.

Answer 26

3 types:
- 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 - Associated with rib-notching (collateral circulation)

Question 27

Signs of Coarctation.

Answer 27

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 28

Symptoms of Coarctation.

Answer 28

Infancy (severe):
- Heart failure
- Failure to thrive

Later life:
- Hypertension
- CV complications (heart failure, MI, CVA, aortic dissection)

Question 29

Describe the treatment of Coarcation

Answer 29

Percutaneous or surgical correction

Question 30

Describe characteristics of Marfan’s syndrome.

Answer 30

• Caused by Fibrillin 1 gene
• Connective tissue weakness
• Aortic/ Mitral valve prolapse – regurgitation
• Vascular – aneurysm, dissection
• Predisposes Aneurysm and dissection
• Risk increased during pregnancy