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This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.
The Bottom Line
- Murmur: early diastolic decrescendo (blowing) murmur at LUSB, best heard sitting up leaning forward in end-expiration
- Wide pulse pressure + bounding (water-hammer) pulses = classic chronic AR signs
- Chronic: well-compensated for years (eccentric LV hypertrophy). Surgery when symptoms develop or LV dilates (LVESD >50 mm or LVEF <=55%)
- Acute (endocarditis, aortic dissection, trauma): sudden severe pulmonary edema with NO compensatory dilation — emergent AVR
- Vasodilator therapy (nifedipine, ACEi) for chronic AR with HTN; no proven benefit in normotensive asymptomatic AR
Overview
Aortic regurgitation results from incompetent closure of the aortic valve, allowing diastolic backflow from the aorta into the LV. Causes include primary valve disease (bicuspid valve, rheumatic, endocarditis, degenerative) and aortic root dilation (Marfan, aortic dissection, syphilitic aortitis, ankylosing spondylitis). Chronic AR is well-tolerated for years through eccentric LV hypertrophy (volume overload pattern). Acute severe AR (endocarditis, dissection) overwhelms the non-compliant LV and is a surgical emergency.
Clinical Features
Symptoms
Chronic: asymptomatic for years. Eventually exertional dyspnea, orthopnea, PND, palpitations, angina
Acute: sudden severe dyspnea, pulmonary edema, cardiogenic shock
Signs
Early diastolic decrescendo blowing murmur at LUSB/Erb point, best with patient sitting forward in expiration
Austin Flint murmur: low-pitched mid-diastolic rumble at apex (regurgitant jet partially closes MV — mimics MS but no opening snap)
Wide pulse pressure (e.g., 170/50 mmHg)
Water-hammer (Corrigan) pulse: bounding with rapid rise and collapse
Eponymous signs: De Musset (head bobbing), Quincke (nail-bed capillary pulsation), Traube (pistol-shot femorals), Muller (uvular pulsation), Hill sign (popliteal SBP >60 mmHg higher than brachial)
Displaced hyperdynamic PMI (LV dilation)
Investigations
First-line
EchocardiogramAssess severity (jet width, vena contracta, holodiastolic flow reversal in descending aorta = severe), LV dimensions (LVESD, LVEDD), LVEF, aortic root size. Serial echo to monitor asymptomatic severe AR
ECGLVH with volume overload pattern (tall R waves, narrow Q waves in lateral leads), LAE
CXRCardiomegaly (boot-shaped), dilated ascending aorta
Second-line
Cardiac MRIQuantitative regurgitant fraction if echo inconclusive. Aortic root assessment
CTA of aortaIf aortic root dilation or dissection suspected
1
Chronic severe AR
- AVR (surgical) indicated when: symptomatic, OR LVEF <=55%, OR LVESD >50 mm (or indexed >25 mm/m2)
- Asymptomatic with normal LV function: serial echo q6-12 months, exercise testing to unmask symptoms
- Vasodilator therapy (nifedipine, ACEi) only if concurrent hypertension — no proven benefit for delaying surgery in normotensive patients
- Avoid bradycardia (increases diastolic time and thus regurgitant volume) — beta-blockers used cautiously
- Aortic root replacement if root >=5.5 cm (>=5.0 cm if Marfan, bicuspid with risk factors, or family history of aortic events)
2
Acute severe AR
- Medical stabilization: IV vasodilators (nitroprusside) to reduce afterload and regurgitant volume, inotropes for cardiogenic shock
- IABP is CONTRAINDICATED in acute AR (augments diastolic pressure and worsens regurgitation)
- Emergent AVR — do not delay
USMLE Step 2 CK Exam Tips
- 1Early diastolic decrescendo murmur at LUSB = AR. Wide pulse pressure + bounding pulses clinch it
- 2Austin Flint murmur (diastolic rumble at apex) mimics MS but has no opening snap — caused by AR jet hitting anterior MV leaflet
- 3IABP is CONTRAINDICATED in aortic regurgitation — it increases diastolic pressure and worsens regurgitation
- 4Acute AR (endocarditis, dissection): pulmonary edema WITHOUT cardiomegaly on CXR (LV has not had time to dilate) — emergent surgery
- 5Chronic AR: operate at LVEF <=55% or LVESD >50 mm — do NOT wait for LVEF to drop to 40%
- 6Marfan + AR: likely aortic root dilation — get aortic imaging; root replacement threshold >=5.0 cm
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