Aortic dissection Flashcards
How common is aortic dissection in comparison to abdominal aortic aneurysm rupture?
3x as common (but still rare)
What is the pathophysiology of aortic dissection?
- tear in the tunica intima of the wall of the aorta
What are 3 possibilities as to how blood enters the tunica media of the aorta in aortic dissection?
- atherosclerotic ulcer leading to intimal tear
- Disruption of vasa vasorum causing intramural haematoma
- De novo intimal tear
What are 5 possible things that can occur following aortic dissection (i.e. blood flow into the tunica media)?
- Extension up or down
- Rupture
- Vessel branch occlusion
- Aortic regurgitation
- Pericardial effusion/ tamponade
What are 7 conditions associated with aortic dissection?
- Hypertension
- Trauma
- Bicuspid aortic valve
- Collagens: Marfan’s syndrome, Ehlers-Danlos syndrome
- Turner’s and Noonan’s syndrome
- Pregnancy
- Syphilis
What is the most important risk factor for aortic dissection?
hypertension
What are 5 clinical features of aortic dissection?
- Chest pain: typically severe, radiates through to back and ‘tearing’ in nature
- Pulse deficit: weak or absent carotid, brachial, or femoral
- Variation (>20 mmHg) in systolic BP between the arms
- Aortic regurgitation (early diastolic decrescendo murmur, eponymous clinical signs)
- Hypertension
What is the nature of the chest pain of aortic dissection?
- severe
- typically ripping or tearing in nature
- occurs suddenly and maximal at onset
- retrosternal or interscapular
- migrating, may go down the back
(but pain not always present)
How can the location of pain in aortic dissection suggest the part of the affected aorta?
retrosternal chest pain: anterior dissection
interscapular pain: descending aorta
What are 3 possible features of aortic dissection which may occur due to the involvement of specific branching arteries?
- Coronary arteries: angina
- Spinal arteries: paraplegia/paraesthesias
- Distal aorta: limb ischaemia
What should you remember about when to consider a diagnosis of aortic dissection, due to the frequency of atypical presentations of this condition?
- consider aortic dissection if there is a combination of chest/ back pain and new or evolving neurological deficits
What may ECG show in aortic dissection? 4 possibilities
- majority have no or non-specific ECG changes
- in minority of patients, ST segment elevation may be seen in inferior leads (right coronary artery dissection)
- Pericarditis changes
- Electrical alternans (tamponade)
What are 2 types of classification for aortic dissection?
- Stanford classification
- DeBakey classification
What are the 2 types of aortic dissection according to the Stanford classification?
- Type A: ascending aorta
- Type B: descending aorta, distal to left subclavian origin
What are the relative proportions of cases of Type A vs Type B aortic dissections (Stanford classification)?
- type A: 2/3
- type B: 1/3
What are the 3 types of aortic dissection according to the 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
What should you do if a patient with suspected aortic dissection is hypo (rather than hyper-) tensive?
ensure not due to upper limb discrepancy caused by an occluded vessel - check BP in arm with best radial pulse
What is a key bedside test to perform in suspected aortic dissection?
ECG
What are 5 key blood tests to perform in suspected aortic dissection?
- FBC: leukocytosis likely
- Creatine Kinase: elevates with renal artery involvement
- Troponin - can cause myocardial ischaemia
- D-dimer: if negative dissection very unlikely, not sufficient to rule out
- Cross-match
What are 5 types of imaging that can be performed in suspected aortic dissection?
- CXR
- Echocardiography: Transthoracic or Traonoesophageal (TOE)
- Helical CT/ CT angiography
- Aortography
- MRI/MRA
What are 8 possible findings on a CXR for aortic dissection?
- normal in 11-16%
- widened mediastinum (56-63%)
- abnormal aortic contour (48%)
- aortic knuckle double calcium sign >5mm (14%)
- pleural effusion (L>R)
- Tracheal shift
- Left apical cap
- Deviated NGT
What type of echocardiography is more sensitive and specific for aortic dissection?
transoesophageal
What are 4 disadvantages of transoesophageal echocardiography for imaging aortic dissection?
- Operator-dependent
- Need sedation
- Less available
- Upper ascending aorta and arch not well visualised
When is it useful to perform echo for suspected aortic dissection?
unstable patients who are too risky to take to CT scanner, and in ICU/perioperatively
Which imaging method is the method of choice for aortic dissection?
CT angiography of chest, abdomen and pelvis
What is the key finding on CT angiography suggesting aortic dissection?
false lumen
What was the previous gold standard imaging for aortic dissection (replaced now by MRI/CT/echo)?
aortography
What are the pros vs cons of MRI/MRA to diagnose aortic dissection?
excellent sensitivity and specificity but low availability
What are the 3 emergency priorities in aortic dissection?
- control BP
- control bleeding
- fluid resuscitation
What are 8 aspects of the immediate management of aortic dissection?
- give oxygen
- wide bore IV access (Swan sheath)
- invasive monitoring
- warn blood bank (cross match 6 units + need for other products)
- correct coagulopathy
- contorl HR and BP (aim for HR 60-80 an BP 100-120)
- IV beta blocker (propranolol, esmolol or labetalol) + vasodilators (e.g. GTN, labetalol, SNP)
- call cardiothoracic surgeon
What are the 2 types of IV drugs you should give as part of the immediate management of aortic dissection and in what order?
- IV beta blocker: propranolol, esmolol, labetalol
- Vasodilators: GTN, labetalol, SNP
start beta blocker first to avoid increased aortic wall stress from reflex tachycardia
What are 4 indications for surgery for aortic dissection?
- Persistent pain
- Type A (Stanford)
- Branch occlusion
- Leak
- Continued extension despite optimal medical management
What must be achieved while awaiting surgical intervention for Type A aortic dissection?
blood pressure should be controlled to target systolic of 100-120 mmHg
What is the management of Type B aortic dissection (Stanford)?
conservative management; bed rest, reduce BP with IV labetalol to prevent progression
What are 6 possible complications of aortic dissection?
- aortic rupture
- aortic regurgitation
- acute myocardial infarction
- cardiac tamponade
- end-organ ischaemia (brain, limbs, spine, renal, gut, liver)
- death
What type of management might be possible for type B aortic dissection in the future?
endovascular repair
