Right ventricular failure from massive pulmonary embolism — FFICM MCQ

Correct answer: D — Massive pulmonary embolism causing acute RV failure

The correct answer is D, massive pulmonary embolism causing acute RV failure. Post-fracture immobility and surgery are major VTE risk factors, and the echo triad of a dilated RV, septal flattening (bowing into the LV, the D-sign) and an underfilled small LV is the classic pattern of acute RV pressure overload from a large embolic burden obstructing pulmonary outflow. This produces obstructive shock: hypotension, tachycardia and rising lactate from reduced cardiac output and tissue hypoperfusion, with unchanged airway pressures and a clear chest X-ray because the lung parenchyma itself is not primarily affected. Current guidance supports bedside echocardiography to identify RV strain and justify emergency reperfusion when CT is unsafe in haemodynamically unstable patients. This clinical and echo picture does not fit a primary pulmonary, cardiac valve or airway pressure problem. Why the other options are wrong: A. Left ventricular failure with pulmonary oedema: this causes a dilated, poorly contractile LV with a small underfilled RV, plus pulmonary oedema on chest X-ray, the opposite of the picture described. C. Tension pneumothorax: this causes markedly raised peak airway pressure, unilateral hyperresonance and mediastinal shift, none of which are present with an unchanged airway pressure and clear film. B. Septic shock from pneumonia: pneumonia would show consolidation on chest radiograph and typically causes vasodilated warm shock with preserved or hyperdynamic ventricles rather than isolated RV dilatation with septal flattening. E. Acute severe mitral regurgitation: this produces LV volume overload and a hyperdynamic LV with pulmonary oedema, not RV dilatation with a small underfilled LV. Key point: RV dilatation with septal flattening and a small underfilled LV in a postoperative, immobile patient is the echocardiographic signature of obstructive shock from massive pulmonary embolism.

Reference: ESC/ERS 2019 Guidelines for the diagnosis and management of acute pulmonary embolism (used in UK critical care practice), diagnostic algorithm for haemodynamically unstable suspected PE, European Heart Journal 2020;41:543-603, https://academic.oup.com/eurheartj/article/41/4/543/5556136