Pulmonary artery catheter (Swan-Ganz catheter) measures pulmonary artery occlusion pressure (PAOP/wedge pressure) as an estimate of left ventricular end-diastolic pressure. PAOP may overestimate LVEDP in which of the following conditions?
- A Aortic regurgitation with wide pulse pressure
- B Left ventricular systolic dysfunction with ejection fraction 15%
- C Mitral stenosis, where high left atrial pressure creates a back-pressure gradient ✓
- D Hypovolaemia with low right ventricular preload
Correct answer: C. Mitral stenosis, where high left atrial pressure creates a back-pressure gradient
Explanation
PAOP is an estimate of left atrial pressure, which in turn estimates LVEDP. In mitral stenosis, the narrowed mitral valve obstructs flow from the left atrium to the left ventricle, creating a pressure gradient across the valve. Left atrial pressure (and therefore PAOP) is elevated out of proportion to actual LV filling pressure, causing PAOP to overestimate LVEDP. Mitral regurgitation can cause V-waves that artificially elevate mean PAOP. LVEDP itself may be elevated in LV systolic dysfunction but PAOP generally tracks it accurately in that case.
Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.
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Written and medically reviewed by the StethoPrep medical team.