inpatient / cardiology

Aortic Dissection

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If You Remember Nothing Else

An aortic dissection is a tear in the intima that results in a false lumen, often due to HTN. AAA and TAA are often due to atherosclerotic disease with smoking, male sex, and age >65yo also being major risk factors. Stanford Type A dissections include the ascending +/- descending and Type B involves just the descending aorta. Type A dissection is managed surgically whereas Type B is usually managed medically unless high risk or "complicated" in which case TEVAR is preferred to open surgery. In both, the goal is to reduce BP, but you should avoid vasodilators without concomitant BB as this can lead to reflex tachycardia which will increase wall stress.
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Clinical Pearls

• Aortic Dissection is a tear in the intima that results in a false lumen - common sites include above the aortic root, the aortic arch, and distal to left subclavian
• HTN is the most common RF seen in ~70% of patients with dissection (40% in those <40 yo who have other more common RFs)
• Stanford Type A (ascending and descending); Type B (descending only) - Type A needs immediate surgical repair and BP reduction, Type B often treated with medical therapy with 80% survival at 5 years if “uncomplicated”; however if continues to expand or “complicated” due to compromise of branch vessels like renal and mesenteric then should have TEVAR (thoracic endovascular aortic repair)
• DeBakey differentiates Type A into Type 1 (ascending AND descending) and 2 (just ascending); Type B is then just Type 3
• If <40yo should be thinking about Marfan, CTD, or a bicuspid valve
• Type B has 9% in-hospital mortality, 16% 1 year, 20% 5 year
• Only ⅓ with dissection will have widened mediastinum on CXR and EKG is often normal though may should nonspecific ST and T-wave changes especially if involves the coronaries
• CTA is the most sensitive and specific test
• D-Dimer has a high negative predictive value, but cannot completely rule out dissection
• Surgery for known AAA if >5.5cm OR growing >0.5cm over 6 months or >1cm over 1 year (for women its 4.5-5cm though controversial)
• AAA and TAA are often due to atherosclerotic disease with smoking, male sex and >65yo being major risk factors
• Should be on the lookout for cardiac tamponade - dissection can cause hemoperitoneum
• Type A can dissect into the coronaries and cause an MI, into the aortic valve and cause regurg, into the carotids and cause stroke
• “Complicated” Type B Dissection is the involvement of aortic branches - celiac trunk, renal arteries (renal failure, oliguria), spinal arteries (weaknes of LEs or paraplegia), occlusion of distal aorta (Leriche Syndrome)
• Over time, the false lumen becomes a hematoma

Trials and Literature

• IRAD - Type A mortality at 3 years if discharged alive is 31% if medically managed and 10% if surgical managed (Circulation, 2006)
• Another IRAD - for Type A surgical repair mortality 26% vs >50% with medical management (JAMA, 2000)
• Recommendations for surveillance of AAA (J Vasc Surg, 2018)

Other Resources

• MD Calc - ADD-RS - assess the risk of acute aortic dissection based on co-morbidities, pain, exam features