Aortic Dissection

Question 1

What is an aortic dissection?

Answer 1

A tear in the tunica intima layer of the aortic wall, causing blood to flow between and splitting apart the tunica intima and media

Question 2

Risk factors for aortic dissection

Answer 2

Male gender
Connective tissue disorders - more common in the younger cases 
Hypertension
Atherosclerosis 
Bicuspid aortic valve

Question 3

Classification of aortic dissections

Answer 3

Stanford classifcation divides dissection into two groups

• group A involves the ascending aorta and can propagate to the aortic arch and descending aorta - the tear can originate anywhere along this path (70%)
• group B dissections don’t involve the ascending aorta (30%)

Question 4

Clinical features of aortic dissections

Answer 4

Tearing chest pain, classically radiating through to the back
Tachycardia
Hypotension (secondary to hypovolaemia due to blood loss)
New aortic regurgitation murmur
Signs of end-organ hypoperfusion (reduces urine output, paraplegia, lower limb ischaemia, abdominal pain or deteriorating consciousness level)
- this is because as the dissection extends it occludes the arterial branches of the aorta
- other features include unequal arm pulses and anuria

Question 5

Differential diagnoses for aortic dissections

Answer 5

MI - troponin and signs of cardiac ischaemia on ECG
PE - SOB and hypoxia on ABG
Pericarditis - pleuritc chest pain and diffuse ST elevation
MSK back pain - no systemic signs of shock

Question 6

Investigations in ?aortic dissections

Answer 6

Blood tests
- FBC, U&Es, LFTs, troponin, coagulation and crossmatch (4 units)
- ABG
ECG - exclude any cardiac pathology
CT angiogram - first line imaging to diagnose and classify
TOE - operator dependent

Question 7

General management for an aortic dissection

Answer 7

Crossmatch 10 units of blood
ITU
Hypotensives - keep systolic at around 100-110mmHg - labetolol IV or calcium channel blockers

Question 8

How are type A aortic dissections managed?

Answer 8

High mortality if left untreated - urgent referral to cardiac/vascular surgery
- transfer to cardiothoracic centre likely
Surgery involves removing the ascending aorta (with or without arch) and replacing with a synthetic graft
- may also require replacement of suspensory apparatus of the aortic valve
- some additional branches of the aortic arch may require reimplantation into the graft

Question 9

How are type B aortic dissections managed

Answer 9

Uncomplicated type B dissections are managed medically
- hypertension management (IV beta-blockers) to rapidly lower systolic pressure, pulse pressure and pulse rate - minimises stress on the dissection
Endovascular repair not advised due to risk of retrograde dissection
Surgical repair indicated only in the presence of certain complications

Question 10

What complications would indicate the need for surgical repair in a type B dissection?

Answer 10

Rupture 
Renal involvement 
Visceral or limb ischaemia 
Refractory pain
Uncontrollable hypertension

Question 11

What is the risk associated with type B dissections?

Answer 11

They can go on to become chronic - risking the formation of an aneurysm
This presents further surgical problems, where endovascular repair may be required

Question 12

Complications associated with aortic dissections?

Answer 12

Aortic rupture
Aortic regurgitation
Myocardial Ischamia - secondary to coronary artery dissection
Cardiac tamponade
Stroke/paraplegia - secondary to cerebral artery or spinal artery involvement