A patient develops ventricular septal rupture 5 days after a large anterior STEMI. On examination there is a new harsh pansystolic murmur at the lower sternal border. Which haemodynamic parameter pattern is expected on Swan-Ganz catheterisation?

• A Elevated PCWP with large V-waves; normal right heart oxygen saturation step-up
• B Low PCWP; elevated pulmonary arterial pressure; oxygen step-up from RA to RV
• C Equalization of diastolic pressures in all four chambers
• D Oxygen step-up from right atrium to right ventricle or pulmonary artery; elevated right-sided pressures ✓

Explanation

In ventricular septal rupture, left-to-right shunting across the defect increases oxygen saturation in the right ventricle (step-up from RA to RV on oximetry is the diagnostic hallmark). This is distinct from papillary muscle rupture causing mitral regurgitation, where large V-waves are seen in the PCWP trace without an O₂ step-up. Equalization of diastolic pressures indicates tamponade or constrictive pericarditis.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.