Aortic Dissection

Question 1

What is acute aortic syndrome?

Answer 1

• Disruption of the layers of arterial wall (tunica adventitia, media and intima)
• Split into 3 subgroups: aortic dissection, penetrating aortic ulcer and intramural haematoma

Question 2

What is aortic dissection?

Answer 2

• Tear in intimal layer of aortic wall
• Blood flows between tunica intima and media and splits it apart
• Can progress distally or proximally

Question 3

Anterograde vs retrograde dissections

Answer 3

• Anterograde propagate towards iliac vessels
• Retrograde propagate towards aortic valve (to root of aorta)

Question 4

Acute vs chronic dissections

Answer 4

• Acute when diagnosed within 14 days or less
• Chronic when diagnosed over 14 days

Question 5

RF of dissection

Answer 5

• Men
• HTN, Atherosclerosis
• Connective tissue disorders - Marfans, Ehlers Danlos
• Bicuspid aortic valve

Question 6

What can retrograde dissections result in?

Answer 6

• Prolapse of aortic valve
• Bleeding into pericardium
• Cardiac tamponade

Question 7

What is a penetrating aortic ulcer?

Answer 7

• Ulcer that penetrates the intima, progressess into media of artery
• Can progress to intramural haematoma, dissection, perforation or aneurysm formation

Question 8

What is an intramural haematoma?

Answer 8

• Contained aortic wall haematoma
• Bleeding in the media
• Can progress to dissection, performation or aneurysm formation

Question 9

Classifications of aortic dissections

Answer 9

• Stanford classification - type A and B
• DeBakey classification - anatomically

Question 10

Stanford classfication

Answer 10

• Type A - ascending aorta, propagate to arch and descending aorta (DeBakey type I and II), tear can originate anywhere along path
• Type B - does not involve ascending aorta, occuring in any other part of aortic arch and descending aorta (DeBakey type III)

Question 11

DeBakey classification

Answer 11

• Type I - originates in ascending aorta, propagates to at least aortic arch
• Type II - confined to ascending aorta
• Type III - originates distal to subclavian artery in descending aorta (IIIa extends distal to diaphragm, IIIb extends beyound diaphragm into abdominal)

Question 12

Summary card classification dissection

Answer 12

Question 13

Presentation of aortic dissection - symptoms

Answer 13

• Tearing chest pain
• Radiating through to back
• BUT often challenging and can be more subtle

Question 14

Clinical signs aortic dissection

Answer 14

• Tachycardia
• Hypotension - secondary to hypovolaemia OR cardiogenic from severe aortic regurge or tamponade
• New aortic regurge murmur - early diastolic
• Signs end organ hypoperfusion - reduced urine output, lower limb ischaemia, lower conc level

Question 15

Investigations for aortic dissection presentation - bloods and bedside

Answer 15

• Baseline bloods
• 4 units of packed red blood cells crossmatched
• ECG - exclude cardiac problem

Question 16

Imaging for aortic dissection

Answer 16

• CT angiogram - allow classification and surgical planning
• Transoesophageal echo - can help if concern re valvular involvement if proximal/retrograde

Question 17

Initial managment aortic dissection - all

Answer 17

• High flow O2
• IV access
• Fluid resucitation - cautious, target pressure for cerebral perfusion if ruptured, if uncomplicated keep systolic pressure below 110mmHg

Question 18

Type A vs type B aortic dissection management

Answer 18

• Type A - surgically, worse prognosis
• Uncomplicated Type B - medically
• Penetrating ulcer/intramural haematoma - medically

Question 19

Following initial management for dissection treated medically/surgically

Answer 19

• Lifelong antihypertensives
• Surveillance imaging - 1,3 and 12 months post discharge, then scans every 6-12 dependent on size of aorta

Question 20

Surgery for type A dissection

Answer 20

• High mortality rate
• Transfer to cardiothoracic centre
• Removal of ascending aorta (+/- arch) with synthetic graft replacement
• If aortic valve damaged, will need repair too
• Any branches involved of aortic arch will need re-implantation into graft
• If very long Type A may need staged procedures

Question 21

Type B management dissection

Answer 21

• Uncomplicated = medically
• Manage HTN with IV beta blockers (labetalol) or CCB 2nd line
• Rapidly lower systolic pressure, pulse pressure and pulse rate to minimise stress of dissection and limit propagation

Question 22

When is surgical management used for type B dissection?

Answer 22

• Not recommended due to risk of retrograde dissection
• Can be considered in complications such as rupture, renal, visceral or limb ischaemia, uncontrollable pain or uncontrolled HTN

Question 23

What can Type B dissections go on to form?

Answer 23

• Chronic - continued leakage into dissection
• Even if stent has been placed
• Can then form aneurysm
• Then will need endovascular repaur for better survival chance

Question 24

Complications of aortic dissection

Answer 24

• Aortic rupture
• Aortic regurgitation
• Myocardial ischaemia - secondary to coronary artery dissection
• Cardiac tamponade
• Stroke/paraplegia - carotid artery extension