Four days after an inferior STEMI, a 60-year-old man develops acute pulmonary edema with a new soft apical holosystolic murmur. There is no thrill. Transthoracic echocardiography is limited by poor windows. Which finding on further evaluation would most strongly distinguish papillary muscle rupture from ventricular septal rupture as the cause?

• A Color Doppler showing eccentric jet into the left atrium ✓
• B Step-up in oxygen saturation at the right ventricular level
• C Elevated right atrial pressure with Kussmaul sign
• D Q waves in leads II, III, and aVF

Explanation

Papillary muscle rupture causes severe acute mitral regurgitation, seen on Doppler as a jet entering the left atrium; the posteromedial papillary muscle supplied solely by the PDA is affected far more often than the anterolateral one. B step-up in oxygen saturation at the right ventricle indicates a left-to-right shunt through a septal rupture, which usually also produces a palpable thrill. Inferior Q waves occur in both conditions since both complicate inferior infarction.

Reference: Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 12th ed.

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Written and medically reviewed by the StethoPrep medical team.