Aortic disease Flashcards
Describe anatomy of thoracic aorta.
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.
Describe the layers of the aorta.
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
Describe the risk factors for atherosclerosis
Risk factors of atherosclerosis: hypertension, hypercholesterolaemia,
smoking,
diabetes,
family history,
male>female.
Describe what conditions atherosclerosis causes.
Atherosclerosis is the pathophysiology processes of: Myocardial infarction,
stroke,
peripheral vascular disease aneurysm
Define Aneurysm
Aneurysm definition - localised enlargement of an artery caused by a weakening of the vessel wall.
Describe the classifications of Aneurysm
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.
Describe signs and symptoms of aneurysms
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
Describe investigations for thoracic aneurysms.
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
Describe aortic dissection
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.
Aetiological factors of aortic dissection.
Aetiological factors:
- Hypertension
- Atherosclerosis
- Marfan’s syndrome
- Bicuspid aortic valve
- Trauma
Describe the classification of thoracic aortic dissection.
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.
Describe symptoms of aortic dissection.
Chest pain – severe, sharp, radiating to back (inter-scapular)
Collapse (tamponade, acute AR, external rupture)
Stroke (involvement of carotid arteries)
Describe signs of aortic dissection.
- Reduced or absent peripheral pulses
- Hypertension or hypotension
- BP mismatch between sides
- Soft early diastolic murmur (aortic regurgitation)
- Pulmonary oedema
- Signs of CVA
Investigation of aortic dissection.
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
Treatment for type A aortic dissection.
Type A
- Blood Pressure control: beta blocker, IVI nitrate, calcium channel blocker, IVI Sodium nitroprusside
- Emergency Surgery
Treatment for type B aortic dissection.
Type B
- Blood pressure control: beta blocker, IVI nitrate, calcium channel blocker, IVI Sodium nitroprusside
- Percuraneous (endo-vascular) intervention
What infection predisposes to thoracic aortic disease
Syphyllis
What inflammatory condition predisposes to thoracic aortic disease
Takayasu’s Arteritis
Describe Pathology of Takayasu’s Arteritis
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.
Treatment of Takayasu’s Arteritis
Treatment includes steroids and immunosuppressive therapy, occasionally the patient might be referred for surgery or percutaneous intervention if there is organ ischaemia.
Describe Syphillis Pathology and treatment
Syphilis - STD caused by treponema pallidum. Treatment with antibiotics prevent late stage complications.
What conginetal conditions can predispose to thoracic aortic aneurysm.
- Bicuspid aortic valve, coarctation and marfan’s syndrome.
Define Bicuspid aortic valve
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.
Describe characteristics of bicuspid aortic valve.
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
Describe Coarctation
Aortic narrowing close to where
Ductus arteriosus inserts
(ligamentum arteriosum)
Describe the 3 types of Coarctation.
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)
Signs of Coarctation.
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
Symptoms of Coarctation.
Infancy (severe):
- Heart failure
- Failure to thrive
Later life:
- Hypertension
- CV complications (heart failure, MI, CVA, aortic dissection)
Describe the treatment of Coarcation
Percutaneous or surgical correction
Describe characteristics of Marfan’s syndrome.
- Caused by Fibrillin 1 gene
- Connective tissue weakness
- Aortic/ Mitral valve prolapse – regurgitation
- Vascular – aneurysm, dissection
- Predisposes Aneurysm and dissection
- Risk increased during pregnancy
