Aortic dissection

Question 1

What is aortic dissection?

Answer 1

A tear in the ascending/descending aorta, caused by a tear in the tunica intima of the wall of the aorta

Question 2

Associations

Answer 2

hypertension: the most important risk factor
trauma
bicuspid aortic valve
collagens: Marfan’s syndrome, Ehlers-Danlos syndrome
Turner’s and Noonan’s syndrome
pregnancy
syphilis

Question 3

Features

Answer 3

1. chest/back pain
   - severe and ‘sharp’, ‘tearing’ in nature
   - pain is typically maximal at onset
2. pulse deficit
   - weak or absent carotid, brachial, or femoral pulse
   - variation (>20 mmHg) in systolic blood pressure between the arms
3. aortic regurgitation
4. hypertension
5. other features may result from the involvement of specific arteries. For example:
   - coronary arteries → angina
   - spinal arteries → paraplegia
   - distal aorta → limb ischaemia
6. ECG - the majority of patients have no or non-specific ECG changes. In a minority of patients, ST-segment elevation may be seen in the inferior leads

Question 4

Classifications

Answer 4

Stanford
type A - ascending aorta, 2/3 of cases
type B - descending aorta, distal to left subclavian origin, 1/3 of cases

DeBakey classification
type I - originates in ascending aorta, propagates to at least the aortic arch and possibly beyond it distally
type II - originates in and is confined to the ascending aorta
type III - originates in descending aorta, rarely extends proximally but will extend distally

Question 5

Investigation

Answer 5

Chest x-ray - widened mediastinum

CT angiography of the chest, abdomen and pelvis IS THE INVESTIGATION OF CHOICE

• suitable for stable patients and for planning surgery
• false lumen is a key finding in diagnosing aortic dissection

Transoesophageal echocardiography (TOE)
more suitable for unstable patients who are too risky to take to CT scanner

Question 6

Management

Answer 6

Type A
surgical management, keep systolic BP 100-120mmHg

Type B*
conservative management
bed rest
reduce blood pressure IV labetalol to prevent progression

Question 7

Complications: backward tear

Answer 7

aortic incompetence/regurgitation
MI: inferior pattern is often seen due to right coronary involvement

Question 8

Complications: forward tear

Answer 8

unequal arm pulses and BP
stroke
renal failure