A 72-year-old man with a history of COPD and recent orthopedic surgery presents with acute dyspnea, tachycardia (HR 115 bpm), and hypoxemia (SpO₂ 88% on room air). CT pulmonary angiography is performed urgently. The radiologist reports: 'Bilateral pulmonary artery filling defects with right ventricular dilatation and flattening of the interventricular septum. No wedge-shaped infarctions.' Based on these findings, which statement BEST describes the hemodynamic significance of this PE?

Explanation

## Hemodynamic Assessment of PE on CTPA ### Severity Classification Based on CT Findings **Key Point:** Bilateral pulmonary artery filling defects with RV dilatation and septal flattening indicate **massive (high-risk) PE** with acute RV strain and hemodynamic compromise. ### CT Findings and Hemodynamic Significance | CT Finding | PE Severity | Hemodynamic Status | Mortality Risk | |------------|-------------|-------------------|----------------| | **Bilateral PA filling defects** | Massive | Compromised | Very High | | **RV dilatation (RV/LV ratio >0.9)** | Massive | Acute strain | Very High | | **Septal flattening** | Massive | RV pressure overload | Very High | | **Unilateral lobar/segmental defect** | Submassive | Borderline | Moderate | | **Subsegmental defect only** | Subsegmental | Minimal | Low | ### RV Strain Markers on CTPA **High-Yield:** Signs of acute RV dysfunction on CTPA indicate **massive PE**: 1. RV/LV diameter ratio >0.9 (RV dilatation) 2. Interventricular septal flattening or bowing into LV 3. Reflux of contrast into IVC and hepatic veins 4. RV free wall hypokinesis These findings correlate with elevated troponin, BNP, and poor prognosis. ### Clinical Significance **Clinical Pearl:** Massive PE with RV strain is a **high-risk presentation** requiring: - Immediate anticoagulation (or thrombolysis if no contraindication) - Consideration of catheter-directed thrombolysis or embolectomy - ICU monitoring for cardiogenic shock - Mortality risk: 25–30% without intervention ### Mnemonic: PE Severity on CTPA **"RV STRAIN"** - **R**ight ventricular dilatation (RV/LV >0.9) - **V**alve reflux (IVC/hepatic vein contrast reflux) - **S**eptal flattening - **T**hrombus (bilateral or central) - **R**ight heart dysfunction - **A**cute hemodynamic compromise - **I**ncreased mortality - **N**eed for aggressive intervention [cite:Harrison 21e Ch 298]