CARDIOLOGY
ACUTE AORTIC SYNDROMES
Definitions (Circ 2003;108:628 & 2010;121:e266; Eur Heart J 2012;33:26)
• Aortic dissection: intimal tear → blood extravasates into Ao media (creates false lumen)
• Intramural hematoma (IMH): vasa vasorum rupture → medial hemorrhage that does not communicate with aortic lumen; 6% of aortic syndromes; clinically identical to AoD
• Penetrating ulcer: atherosclerotic plaque penetrates elastic lamina → medial hemorrhage
Classification (proximal twice as common as distal)
• Proximal: involves ascending Ao, regardless of origin (= Stanford A, DeBakey I & II)
• Distal: involves descending Ao only, distal to L subclavian art. (= Stanford B, DeBakey III)
Risk factors
• Hypertension (h/o HTN in >70% of dissections); male sex (~70% 
); cocaine
• Connective tissue disease: Marfan (fibrillin-1): arachnodactyly, joint disloc., pectus, ectopia lentis, MVP; Ehlers-Danlos type IV (type III procollagen): translucent skin; bowel or uterine rupture; Loeys-Dietz (TGFbR); annuloaortic ectasia, familial AoD; PCKD
• Congenital aortic anomaly: bicuspid AoV, coarctation (eg, in Turner’s syndrome)
• Aortitis (eg, Takayasu’s, GCA, Behçet’s, syphilis, now rare); pregnancy (typ. 3rd trim.)
• Trauma: blunt, deceleration injury; IABP, cardiac or aortic surgery, cardiac catheterization
Diagnostic studies (Circ 2005;112:3802; & 2010;121:e266; Annals 2006;166:1350)
• Check bilateral BP and radial pulses for symmetry
• CXR: abnl in 60–90% (↑ mediastinum, left pl effusion), but cannot be used to r/o dissection
• CT: quick, noninvasive, readily available, Se ≥93% & Sp 98%; however, if 
& high clin. suspicion → additional studies (2⁄3 w/ AoD have ≥2 studies; AJC 2002;89:1235)
• TEE: Se >95% prox, 80% for distal; can assess cors/peric/AI; “blind spot” behind trachea
• MRI: Se & Sp >98%, but time-consuming test & not readily available
• Aortography: Se ~90%, time-consuming, cannot detect IMH; can assess branch vessels
• D-dimer: Se/NPV ~97%; ? <500 ng/mL to r/o dissec (Circ 2009;119:2702); does not r/o IMH
Treatment (Lancet 2008;372:55; Circ 2010;121:1544; JACC 2013;61:1661)
• Initial Medical: ↓ dP/dt targeting HR ~60 & central BP 100–120 (or lowest that preserves perfusion; r/o pseudohypotension, eg, arm BP ↓ due to subclavian dissection)
first with IV bB (eg, propranolol, esmolol, labetalol) to blunt reflex ↑ HR & inotropy that would occur in response to vasodilators; verap/dilt if bB contraindic.
then ↓ SBP with IV vasodilators (eg, nitroprusside)
control pain with MSO4 prn to blunt sympathetic response
• Proximal: surgery (root replacement); all acute; chronic if c/b progression, AI or aneurysm
• Distal: med Rx unless c/b progression, branch artery involvement → malperfusion/ ischemia, refractory HTN, refractory pain, rapid ↑ aneurysm size, rapid ↑ false lumen size. Repeat imaging: routinely (eg, 7 d, 3 wk, then q yr) & with any clinical or significant lab Δ. If complic., endovascular repair (covered stent graft to seal off entry, fenestrate flap, open occluded branch) preferred over surgery due to possible ↓ mort. ( JACC 2013;61:1661).
Complications
• Rupture: pericardial sac → tamponade (avoid pericardiocentesis unless PEA); blood in pleural space, mediast., retroperitoneum; ↑ in hematoma on imaging portends rupture.
• Malperfusion (obstruction of branch artery)
can be static (avulsed/thrombosed) or dynamic (Δs in pressure in true vs. false lumen)
coronary → MI (usually RCA → IMI, since dissection often along outer Ao curvature)
innominate/carotid → CVA, Horner; intercostal/lumbar → spinal cord ischemia/paraplegia
innominate/subclavian → upper extremity ischemia; iliac → lower extremity ischemia
celiac/mesenteric → bowel ischemia; renal → acute renal failure, refractory HTN
• AI: due to annular dilatation or disruption or displacement of leaflet by false lumen
• Mortality: 1–2%/h × 48 h for acute proximal; 10% at 30 d for acute distal