Aortic dissection (Complete*)

Question 1

How does aortic dissection occur?

Answer 1

Tear in the tunica intima causes a false lumen for blood to flow through

Question 2

What are the risk factors for aortic dissection?

Answer 2

Hypertension

Trauma

Bicuspid aortic valve

Connective tissue disorders (e.g. Ehler’s-danlos syndrome, Marfan’s syndrome)

Turner’s syndrome and Noonan’s syndrome

Pregnancy (Due to hormonal effect on vasculature)

Syphillis (Lesions tend to target aorta)

Cocaine/amphetamine use (Produces abrupt severe hypertension)

Question 3

What are the main signs/symptoms of aortic dissection?

Answer 3

Symptoms:

Ripping chest pain/interscapular pain

• Radiates to the back

Syncope

Signs:

Weak or absent pulses

Radio-radial or radio-femoral delay

Variation in systolic blood pressure between both arms (> 20 mmHg)

New onset early-diastolic murmur (aortic regurgitation)

Hypertension

Symptoms depending on how large the dissection is:

Syncope

Renal failure

Bowel/limb ischaemia

Question 4

What are the main characteristics of aortic dissection chest/back pain?

Answer 4

Pain located in chest or interscapular which radiates to the back

Maximal pain on onset

Described as ripping/tearing

Question 5

What are some distinguishing features of a forward tear and backward tear?

Answer 5

Complications of a forward tear:

Unequal arm pulses and BP

Stroke

Renal failure

Complications of a backward tear

Aortic regurgitation

Inferior MI: Usually because right coronary artery affected

N.B. Backward tear means its enlarging against blood flow (e.g. toward heart). Forward tear is along direction of blood flow

Question 6

What type of murmur is heard in patients with aortic regurgitation?

Answer 6

Early-diastolic murmur

Question 7

What are the two types of aortic dissection according to the Stanford criteria?

Answer 7

Type A: Dissection occured in ascending aorta (2/3rd)

Type B: Dissection occured in descending aorta (1/3rd)

Question 8

What investigations should be done in patients suspected of having aortic dissection?

Answer 8

A-E approach first before investigations as they present acutely unwell

Bedside:

Basic obs: Assess haemodynamic status

ECG: Non specifc or no ECG changes (May show ischaemia if it affects coronary arteries however)

Bloods:

VBG

Troponin: May be raised

D-dimer: May be positive

Coagulation screen + G&S: Prep for surgery

U&Es: Monitor for renal impairment

LFTs: Baseline

Imaging:

CXR: Widened mediastinum

CTA: 1st line diagnostic For stable patients with planned surgery. Would show a false lumen.

Transoesophageal echocardiography (TOE): For patients too unstable for CTA

Question 9

When would you choose CTA over transoesophageal ECHO and vice versa?

Answer 9

CTA: For stable patients suitable for surgery

Transoesophageal echocardiography (TOE): For patients too unstable for CTA

Question 10

What type of aortic dissection can be seen on this image?

Answer 10

Type A

Can see flap in the ascending aorta

Question 11

What type of aortic dissection can be seen on this image?

Answer 11

Type B

Can see flap in desecending aorta

Question 12

What findings on CXR may be seen in aortic dissection?

Answer 12

Widened mediastinum

Double or irregular aortic contour

N.B. 10-15% of patients have a normal CXR

Question 13

Question 14

What blood test, if negative, lowers likelihood of aortic dissection?

Answer 14

D-dimer

N.B. Doesnt exclude but likelihood of dissection is very low

Question 15

What is the management plan for type A dissections?

Answer 15

Urgent discussion with on-call vascular and/or cardiothoracic team and critical care team

A-E approach

Cardiac monitoring

• Arterial line for continous BP monitoring

Medicine:

First-line: IV labetolol

Second-line: IV calcium channel blockers

• Nicardipine
• Non-dihydropyridine agents (e.g. verapamil)

Refractory cases: IV nitrates or sodium nitroprusside

IV opiate analgesia

• Pain management can help reduce sympathetic tone

Surgical: Definitive management

Open surgical repair (e.g. aortic synthetic graft)

Question 16

What is the definitive management for type A dissections?

Answer 16

Aortic synthetic graft

Question 17

What HR and BP measurements should a patient with type A aortic dissection be within prior to surgical intervention?

Answer 17

100-120mmHg systolic

HR 60-80 bpm

Question 18

What is used second-line in management of BP in patients with dissection

Answer 18

IV calcium channel blockers

• Nicardipine
• Non-dihydropyridine CCBs

Question 19

What is used in management of refractory hypertension?

Answer 19

IV nitrates
or
IV sodium nitroprusside

Question 20

What is the management plan for type B aortic dissection?

Answer 20

Urgent discussion with on-call vascular and/or cardiothoracic team

A-E approach

Cardiac monitoring

• Arterial line for continous BP monitoring

Medicine:

First-line: IV labetolol

Second-line: IV calcium channel blockers

• Nicardipine
• Non-dihydropyridine agents

Refractory cases: IV nitrates or sodium nitroprusside

IV opiate analgesia

• Pain management can help reduce sympathetic tone

Surgical:

Complicated type B dissection:

Endovascular stent graft placement

• Aka TEVAR (thoracic endovascular aortic repair)

Question 21

Why is labetalol used in management of BP in aortic dissection?

Answer 21

Labetalol has a combination of beta and alpha blocker effects therefore preventing tachycardia secondary to rapid BP lowering.

Question 22

Type B dissections are mostly managed conservatively except in cases of complicated tears.
What are considered complicated type B dissections?

Answer 22

Any of the following:

• Aortic rupture
• Impending rupture
• Refractory hypertension
• Rapidly expanding aortic diameter
• Malperfusion due to branch vessel occlusion or aortic lumen compression
• Ongoing pain

Question 23

What type of surgical intervention is indicated for complicated Type B dissections?

Answer 23

Endovascular stent graft

Question 24

How does the management plan differ between type A and B aortic dissections?

Answer 24

Type A can undergoe surgical management (e.g. aortic graft)

Type B is managed mainly conservatively if uncomplicated