AORTIC DISSECTION Flashcards
What is an aortic dissection?
Disruption of the medial layer of the aorta due to blood leading to separation of the layers resulting in a true lumen and false lumen
This most commonly results from an intimal tear allowing blood to enter the intima-media space. As this false lumen fills with blood, it may propagate proximally or distally. This results in either rupture through the adventitia or re-entry to the true lumen via a second intimal tear.
Where does aortic dissection most commonly occur?
Ascending aorta (mostly right lateral area) and aortic arch
Why is the right lateral area of the ascending aorta the most common site of a tear of the intima layer?
As this is under the most stress from blood exiting the heart
What are the 2 systems used for aortic dissection classification?
Stanford
DeBakey
Whats the Stanford criteria for aortic dissection?
Type A: Ascending aorta is involved
Type B: Ascending aorta is not involved
What is the DeBakey criteria for an aortic dissection?
Type I: Involves the ascending aorta, dissection extends into arch and beyond
Type II: Limited to the ascending aorta (proximal to brachiocephalic artery)
Type IIIa: starts at the descending thoracic aorta (distal to left subclavian artery, proximal to coeliac artery i.e. below the diaphragm)
Type IIIb: Involves descending thoracic aorta and abdominal aorta
What are the risk factors for aortic dissection?
Hypertension - most important
Age
Male
Smoking
Poor diet
Reduced physical activity
Raised cholesterol
Conditions of aorta e.g. coarctation of aorta, bicuspid aortic valve, aneurysms
Procedures on aorta e.g. aortic valve replacement, CABG
Connective tissue disorders e.g. ehlers-danlos syndrome and Marfan’s syndrome
Turner’s syndrome and Noonans syndrome
Pregnancy
Syphilis
Cocaine use
Trauma
Whats the pathophysiology of aortic dissection?
Constant exposure to high pulsatile pressure and shear stress leads to a weakening of the aortic wall in susceptible patients resulting in an intimal tear. Following this, blood flows into the intima-media space, creating a false lumen
How does aortic dissection present?
Chest pain that’s sharp, severe, tearing in nature, maximal at onset, and radiates into upper back
Hypertension
Pulse deficit - weak carotid/brachial/femoral pulses
variation in systolic bp between arms
Syncope
Aortic regurgitation
Angina, paraplegia or limb ischaemia
Why can aortic dissection present with angina?
As it can be a coronary artery dissection
Why can aortic dissection present with paraplegia?
When aortic dissection extends into the descending aorta causing insufficient perfusion of segmental arteries supplying the spinal cord
Why can aortic dissection present with limb ischaemia?
Occasionaly an aortic dissection may extend into arteries lower down e.g. iliac artery
How should you investigate aortic dissection?
ECG to exclude MI
Chest x-ray - widened mediastinum
CT angiography of the chest, abdomen and pelvis is the investigation of choice
Transoesophageal echocardiography (TOE) - more suitable for unstable patients who are too risky to take to CT scanner
How do you manage a type A aortic dissection?
Emergency surgical management
(Midline sternotomy to remove the section of the aorta with the defect in the wall and replace it with a synthetic graft)
How do you manage a type B aortic dissection?
Conservative management
Bed rest
reduce blood pressure IV labetalol to prevent progression
Thoracic endovascular aortic repair (TEVAR) may be used
