Aortic Dissection

Cardiology

OverviewWhoPresentationMechanismWorkupManagementPivots

Illness script · Cardiology

Aortic Dissection

Tear in aortic intima allows blood to enter and split the media, creating a false lumen; classified Type A (ascending) vs Type B (descending).

This illness script for Aortic Dissection covers predisposing factors, classic presentation, mechanism, workup, management, and the clinical pivots that separate it from look-alikes—written for USMLE Step 1 and clerkship reasoning.

Updated Jul 19, 2026All scripts

01

Predisposing factors

  • HTN (#1 risk factor) — chronic wall stress accelerates medial degeneration
  • Marfan/Ehlers-Danlos syndrome — cystic medial necrosis in young patients
  • Bicuspid aortic valve — associated aortopathy
  • Cocaine use — acute severe hypertensive surge
  • Pregnancy (3rd trimester/peripartum) — hormonal medial changes
  • Prior cardiac surgery or aortic instrumentation

02

Presentation

  • Abrupt, maximal-at-onset tearing/ripping chest pain radiating to the back (interscapular)
  • Pain migrates as dissection propagates distally
  • Pulse deficit or BP differential >20 mmHg between arms (pathognomonic finding)
  • Aortic regurgitation murmur in Type A (decrescendo diastolic)
  • Neurologic deficits (stroke, Horner syndrome, paraplegia) from branch occlusion
  • Syncope suggests tamponade or severe AR in Type A

03

Pathophysiology

  • Intimal tear → blood dissects through tunica media under pulsatile pressure
  • False lumen propagates antegrade (and sometimes retrograde) along aorta
  • Branch vessel occlusion causes end-organ ischemia (stroke, MI, renal failure, limb ischemia)
  • Type A: involves ascending aorta → risk of cardiac tamponade, aortic regurgitation, coronary occlusion

04

Diagnostics

  • CXR: widened mediastinum (>8 cm) — screening clue, not definitive
  • CT angiography chest/abdomen/pelvis with contrast — first-line diagnostic test of choice
  • TEE — gold standard if CT unavailable or hemodynamically unstable (bedside capable)
  • D-dimer <500 ng/mL has high NPV to help rule out in low-pretest-probability cases
  • ECG often normal or shows LVH; ST changes suggest coronary involvement (don't give thrombolytics!)

05

Management

  • Immediate IV beta-blocker (esmolol/labetalol) — reduce HR <60 and SBP 100–120 mmHg
  • If beta-blocker contraindicated, use calcium channel blocker (verapamil/diltiazem)
  • Type A dissection → emergent surgical repair (mortality ~1–2%/hour untreated)
  • Type B uncomplicated → medical management (anti-impulse therapy) in ICU
  • Type B complicated (malperfusion, rupture) → TEVAR (thoracic endovascular aortic repair)
  • Avoid anticoagulation; avoid thrombolytics absolutely

06

Clinical pivots

How to separate this script from the look-alikes that show up on exams and on the wards.

  • Acute MI/ACS

    Dissection pain is maximal at onset and tearing; ACS builds gradually — giving thrombolytics for dissection is fatal

  • Pulmonary Embolism

    PE causes pleuritic pain + dyspnea + hypoxia; dissection has tearing back pain + pulse differential

  • Aortic Aneurysm Rupture

    Rupture presents with hypotension/shock and pulsatile abdominal mass; dissection is intramural without free rupture initially

  • Musculoskeletal/Thoracic Pain

    Dissection is abrupt, severe, maximal at onset with pulse differential — musculoskeletal pain is positional and gradual

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Educational use only. This illness script is a study framework, not medical advice. Confirm decisions with current guidelines and your clinical supervisors.