Genetic: Marfan’s, Turner’s, Ehlers-Danlos type IV, familial thoracic aortic aneurysm types 1 & 2
Cong bicuspid AoV & coarctation of aorta.
Arteritis (Takayasu, Giant Cell), syphilis
Iatrogenic dissection (Cx of cardiac catheterisation, cardiopulmonary bypass or balloon valvotomy).
Asc aorta: 50%
Distal aorta: 20%
Type A involves ascending aorta (DeBakey types I & II) 60–70%
Type B does not involve the ascending aorta (DeBakey type III).
Type I: ascending aorta, aortic arch, and descending aorta.
Type II: ascending aorta only
Type III: descending aorta distal to left SCA, IIIa stops before & IIIb after diaphragm
Can be quite variable.
History: >90% have pain – sudden severe, worst-ever pain of short duration. 75% chest (A>B), 50% back (B>A) and 30% abdo pain. Sharp (65%) or tearing (50%). Radiates in 30% to back, arms, chest, abdo. Neurological features (15–40%) – syncope, TIA, focal neurological deficits (this plus CP = very likely dissection).
Examination: ~50% have BP (B>A), unequal pulses (<40%), BP diff>20mmHg significant, may have diastolic murmur of AR (A>B), S3 or Austin Flint murmur. Evidence of tamponade (25% in A). Also may have signs of CVA/TIA, limb ischaemia, visceral ischaemia, paraplegia or Horner’s.
FBC, UEC, Trop/CK, coags, XM, D-Dimer, [smooth muscle myosin heavy chain not useful]
70% abnormal (non-specific ST-T wave changes, LVH or ischaemic changes – <5% have pattern indication for thrombolysis – which would be disastrous if given)
CXR – cannot conclusively diagnose or exclude dissection, but 90% abnormal including:
Wide mediastinum in 60% (AP supine>8cm; PA erect>6cm or >25% chest width)
Obscured aortic knob; abnormal aortic contour
Ring sign – separation of aortic knuckle calcification > 5–10mm
Apical cap (i.e. pleural blood)
Left pleural effusion
Deviation of nasogastric tube rightward
Deviation of trachea rightward and/or left main stem bronchus downward
Left paraspinal stripe
Disparity in ascending/descending aorta size or double density of aorta
Loss of aorto-pulmonary window
Loss of paratracheal stripe
Multidetector CT angiography:
100% sens/98% spec. Can’t assess AV. SE: contrast, Xrad
80% sens, 90 spec for asc dissections & assessing AV. Not good for desc ones.
98% sens, 95% spec. Less sensitive for distal asc & desc aorta. Op-dependent.
Aortic angiography (aortogram):
~90% sensitive, ~95% specific. Requires contrast. But can assess involvement of branches. Possibility of cannulating false lumen.
98–100% sensitive & specific but not usually stable enough and not readily available.
ABC, O2, analgesia, monitoring, arterial line, CVL, good access (2 x large bore IVC).
Aim BPsys 100–110mmHg with nitroprusside titrate 0.25–10µg/kg/min IV or labetalol IV
Intravenous beta blockers (or CCB if COPD) to keep HR 60–80 & as negative inotrope,e.g. propranolol 0.5–1mg IV q5min or esmolol.