Aortic dissection

Question 1

describe the classification of aortic dissection?

Answer 1

Type A : Ascending aorta ( most common ) 70% - retrosternal chest pain

Type B: Descending aorta ( distal to the left subclavian artery) 30% - interscapular pain

Question 2

define aortic dissection

Answer 2

condition where the tear in the aortic intima allows the blood to surge into the aortic wall -> causing a split between the inner and outer tunica media-> creating a false lumen

Question 3

summarise the epidemiology of aortic dissection?

Answer 3

most common in males aged 40-60 years

Question 4

give the cause and common risk factors for aortic dissection?

Answer 4

usually preceded by degenerative changes in the smooth muscle of the aortic media

HYPERTENSION

• Aortic atherosclerosis
• Connective tissue disease (e.g. Marfan’s, Ehlers-Danlos, SLE)
• Congenital cardiac abnormalities (e.g. coarctation of the aorta)
• Aortitis
• Iatrogenic (e.g. during angioplasty/angiography)
• Trauma
• Crack cocaine
• Bicuspid aortic valve
• annuloaortic ectasia
• Coarction - aorta narrowing

Question 5

what are the main presenting symptoms of aortic dissection?

Answer 5

MAIN SYMPTOM: sudden central ‘tearing’ pain, it may radiate to the back in between the shoulder blades (it can mimic MI)

Other symptoms caused by obstruction of branches of the aorta:

• Carotid artery -> hemiparesis, dysphasia, blackout, parasthesia
• Coronary artery -> chest pain (angina or MI)
• Subclavian artery -> ataxia, loss of consciousness
• Anterior spinal artery àparaplegia
• Coeliac axis -> severe abdominal pain (due to ischaemic bowel)
• Renal artery -> anuria, renal failure
• Hypoperfusion of the target organs of these major arteries can give rise to other symptoms
• If dissection moves proximally, may develop aortic valve incompetence, inferior MI and cardiac arrest

Question 6

what are the features of Marfan’s syndrome?

Answer 6

tall stature

arachnodactyl

pectus excavatum

hypermobile joints

high arched palate

narrow face

Question 7

What are the features of Ehler’s danlos syndrome that can help in the diagnoses of aortic dissection?

Answer 7

Type IV Ehlers-Danlos syndrome predisposes to both aneurysms and/or dissections

Features include translucent skin, easy bruising, hypermobility of small joints, and premature ageing of the skin (acrogeria)

Question 8

what are the signs of aortic dissection on physical examination?

Answer 8

1. Murmur on the back (below the left scapula), descending to the abdomen
2. Hypertension
3. Blood pressure difference between the two arms > 20 mm Hg
4. Wide pulse pressure(large difference between systolic and diastolic pressure)
5. Hypotension may suggest tamponade

• Check for pulsus paradoxus = abnormally large decrease in systolic blood pressure and pulse wave amplitude during inspiration

This may indicate:

• Tamponade
• Pericarditis
• Chronic sleep apnoea
• Obstructive lung disease

6. Signs of Aortic Regurgitation

• High volume collapsing pulse
• Early diastolic murmur over aortic area

7. Unequal arm pulses
8. There may be a palpable abdominal mass

Question 9

what is pulsus paradoxus and what may it indicate?

Answer 9

abnormally large decrease in systolic blood pressure and pulse wave amplitude during inspiration

This may indicate:

Tamponade

Pericarditis

Chronic sleep apnoea

Obstructive lung disease

Question 10

what are the signs of aortic regurgitation?

Answer 10

high volume collpasing pulse

early diastolic murmur over aortic area

Question 11

what are the appropriate investigations for aortic dessection

Answer 11

bloods

CXR

ECG

CT Thorax/CT angiogram- ORDERED AS SOON AS SUSPECTED

Question 12

what bloods do you need in aortic dissection?

Answer 12

FBC- anaemia may present in haemorrhage

X match 10 units of blood- prep for surgery

U and Es- check renal function ( may be compromised)

LFTs may be compromised

lactate- indicative of malperfusion ( may be elevated)

cardiac enzymes- exlcude MI

Question 13

what can be seen on the CXR in aortic dissection?

Answer 13

( exclude other pulmonary causes of chest pain )

widened mediastinum

Question 14

what can be seen on the ECG in aortic dissection?

Answer 14

may be normal

if ostia of right coronary artery is compromised-> get signs of:

• left ventricular hypertrophy
• inferior MI- ST elevation in inferior leads

Question 15

What can be seen on the CT thorax/aniogram in aortic dissection?

Answer 15

ordered as soon as suspected- include chest,abdo and pelvis to visualise the extent of aneurysm and to see if its suitable for an endo vascular repair

=> shows false lumen

Question 16

what investigations should you consider in a patient suspected of aortic dissection?

Answer 16

D-dimer: should be positive

Magnetic resonance angiography: very accurate to show intimal flap but rarely used in an acute setting due to difficulty to obtain

Trans-thoracic echo: may show the intimal flap – done more in the emergency department or op theatre if there is any question about diagnosis or CTA is unavailable or contraindicated