- Aortic lining intima tear (usually <3cms distal to AoV or left SC artery) haemorrhage into false lumen double lumen aorta.
- Dissection can result in
- Occlusion of aortic branches organ → ischaemia
- False lumen rupture back into aorta or into mediastinum, pericardium, GIT or IVC
- Commonest emergency affecting the aorta. 4:100,000 per year. 25% Post Mortem diagnosis
- 2M:1Ft im
- Usual age range: 50–70y & rare <40y unless inherited, congenital, iatrogenic conditions.
- HT in up to 75%
- Atherosclerosis & so smoking and cholesterol.
- Genetic: Marfan’s, Turner’s, Ehlers-Danlos type IV, familial thoracic aortic aneurysm types 1 & 2
- Cong bicuspid AoV & coarctation of aorta.
- Cocaine use
- Arteritis (Takayasu, Giant Cell), syphilis
- Iatrogenic dissection (Cx of cardiac catheterisation, cardiopulmonary bypass or balloon valvotomy).
- Asc aorta: 50%
- Arch: 30%
- 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.
Surgical: (cardiology & cardiothoracic consultations)
- If type A (type I and II) to prevent aortic rupture, tamponade, and relieve AR.
- If type B (distal dissection) often medical Mx unless significant AR, tamponade, leaking aneurysm, major vessel involved (& so limb/visceral ischaemia), or continued dissection.
- Rel CI: Poor outcome for type III dissections due to compromise of spinal blood flow.
- Acute dissections with ischaemia are treated usually endovascularly by stenting, graft or aortic fenestrations.
- Chronic dissections continue to be managed by open surgical techniques, usually grafts.
- If the aortic valve is involved it may need resuspension or replacement.
- Up to 20–50% die before reaching hospital, 30% in hospital.
- Operative mortality ~25%.
- Aortic rupture has 80% mortality.
- If undiagnosed: 50% mortality @ 48hrs rising by 1%/hr.