Match each diagnostic finding associated with pericardial effusion or cardiac tamponade to its corresponding clinical significance: Findings: 1. Pulsus paradoxus 2. Echo-free space 3. Right-sided chamber diastolic collapse 4. "Water-bottle" cardiac silhouette Significances: A. Pericardial fluid visible between the epicardium and pericardium on echocardiography B. Exaggerated drop in systolic arterial blood pressure during inspiration C. Radiographic sign indicative of a large pericardial effusion D. Echocardiographic hallmark of cardiac tamponade

Each pairing links a finding with the meaning given in the lecture. **Pulsus paradoxus** describes an exaggerated inspiratory systolic-pressure fall. On echocardiography, an echo-free space between epicardium and pericardium represents effusion, while diastolic collapse of right-sided chambers supports tamponade. A chest radiograph may show a water-bottle configuration when the effusion is relatively large; a normal-sized silhouette does not rule out a smaller effusion. **Key takeaway:** Echocardiography is more sensitive for effusion than chest radiography and also assesses haemodynamic effects. **Glossary:** **Epicardium**: the outer surface of the heart. **Water-bottle configuration**: an enlarged, rounded cardiac shadow on a chest radiograph.