Aortic Dissection

Risk factors

• Long-standing hypertension (most common — >70% of dissections)
• Connective tissue disease: Marfan, Ehlers-Danlos (vascular), Loeys-Dietz, Turner syndrome
• Bicuspid aortic valve, prior aortic aneurysm or coarctation
• Cocaine or methamphetamine use (acute hypertensive surge)
• Pregnancy (especially third trimester) in patients with predisposing aortopathy
• Iatrogenic: cardiac catheterization, surgery
• Inflammatory aortitis (giant cell, Takayasu, syphilis)
• Family history of aortic dissection
• Trauma (deceleration injury — typically at aortic isthmus)

Pathophysiology

Chronic shear stress combined with medial degeneration (cystic medial necrosis) weakens the aortic wall. An intimal tear allows pulsatile blood to dissect into the media, creating true and false lumens. Propagation can shear off branch vessels (causing stroke, MI, mesenteric, renal, or limb ischemia), produce acute aortic regurgitation by tearing the valve apparatus, rupture into the pericardium (tamponade), or rupture into the pleural space.

Clinical presentation

Differential diagnosis

• Acute coronary syndrome — Substernal pressure with positive troponin and regional ST changes — but always consider dissection if pain is tearing or back-radiating; type A can cause inferior STEMI from RCA dissection
• Pulmonary embolism — Pleuritic pain, hypoxia, RV strain on ECG/echo; D-dimer and CTPA
• Esophageal rupture (Boerhaave) — Severe pain after vomiting; subcutaneous emphysema; pneumomediastinum
• Pericarditis — Sharp positional pain, diffuse ST elevation with PR depression; lacks pulse deficit
• Pneumothorax — Unilateral absent breath sounds, dyspnea; CXR diagnostic
• Stroke (other cause) — Focal deficit with negative aortic imaging
• Acute abdomen / mesenteric ischemia — Type B dissection can cause mesenteric malperfusion mimicking primary GI emergency

Diagnostic workup

Diagnostic algorithm

flowchart TD
  A[Tearing chest/back pain<br/>± pulse deficit, BP differential] --> B[ECG + CXR<br/>+ stat CT angio]
  B --> C{Diagnosis confirmed}
  C --> D[IV beta-blocker FIRST<br/>esmolol or labetalol<br/>HR <60, SBP 100-120]
  D --> E[Add IV nitroprusside<br/>or nicardipine if BP still high]
  E --> F{Stanford classification}
  F -->|Type A| G[Emergent surgical repair<br/>open ± root/valve]
  F -->|Type B uncomplicated| H[Continued medical management<br/>ICU + serial imaging]
  F -->|Type B complicated<br/>malperfusion / rupture / pain| I[TEVAR]
  G --> J[Lifelong BP control<br/>+ surveillance imaging]
  H --> J
  I --> J

Treatment

Complications

• Aortic rupture and exsanguination
• Cardiac tamponade (type A)
• Acute severe aortic regurgitation and heart failure (type A)
• Myocardial infarction (RCA dissection — type A)
• Stroke, paraplegia (spinal cord ischemia)
• Mesenteric, renal, or limb ischemia (malperfusion)
• Late aneurysm formation in residual false lumen
• Postoperative complications: bleeding, stroke, renal failure

PANCE pearls

• Always control HEART RATE BEFORE BLOOD PRESSURE — give beta-blocker first, vasodilator second.
• Stanford A = always surgery. Stanford B uncomplicated = always medical first.
• Pulse deficit or BP differential >20 mmHg between arms in a patient with chest pain is dissection until proven otherwise.
• NEVER anticoagulate suspected dissection — exclude with imaging before treating presumed ACS in tearing-pain presentations.
• Inferior STEMI from RCA dissection is a notorious type A pitfall — check the mediastinum and consider TEE before catheterization.

References

• ACC/AHA 2022 Aortic Disease — 2022 ACC/AHA Guideline for the Diagnosis and Management of Aortic Disease (Isselbacher et al., JACC 2022)
• ESC 2014 Aortic Diseases — 2014 ESC Guidelines on the Diagnosis and Treatment of Aortic Diseases (Erbel et al., Eur Heart J 2014)
• IRAD — International Registry of Acute Aortic Dissection (Hagan et al., JAMA 2000)
• INSTEAD-XL — Endovascular Repair of Type B Aortic Dissection: Long-Term Results (Nienaber et al., Circ Cardiovasc Interv 2013)