## Hemodynamic Consequences of Acute PE **Key Point:** The statement that RV dilatation in acute PE is "always irreversible" is FALSE. Acute RV dilatation in PE is often reversible if the thrombus is removed or resolves, especially in previously healthy individuals. ### Pathophysiology of Acute PE 1. **Mechanical obstruction** → sudden increase in pulmonary vascular resistance (PVR) 2. **Hypoxic pulmonary vasoconstriction** → further elevation of PVR 3. **Right ventricular strain** → acute cor pulmonale (RV dilatation and dysfunction) 4. **Reduced left ventricular preload** → decreased cardiac output and systemic hypotension ### Pulmonary Infarction **High-Yield:** Pulmonary infarction occurs in only 10% of PE cases because the lungs have dual blood supply (pulmonary + bronchial circulation). Infarction is more likely when: - Bronchial circulation is compromised - Pre-existing cardiopulmonary disease (heart failure, pneumonia) - Peripheral location of embolus ### Reversibility of RV Changes **Clinical Pearl:** In acute PE: - RV dilatation develops acutely due to increased afterload - In survivors, RV function typically normalizes over weeks to months - Chronic thromboembolic pulmonary hypertension develops only if emboli persist or recur - RV dysfunction is reversible in most cases unless there is recurrent embolism ### Comparison: Acute vs. Chronic PE Effects | Feature | Acute PE | Chronic PE | |---------|----------|------------| | RV dilatation | Acute, often reversible | Progressive, may become fixed | | PVR elevation | Sudden, mechanical + reflex | Gradual, progressive remodeling | | Pulmonary infarction | Rare (10%) | Not typical | | RV recovery | Usually complete if thrombus resolves | May have residual dysfunction | [cite:Robbins 10e Ch 10]
Sign up free to access AI-powered MCQ practice with detailed explanations and adaptive learning.