Key Echo Findings
- RA collapse
- RV diastolic collapse
- Dilated IVC with minimal respiratory variation
- Large pericardial effusion
- 25% drop in mitral inflow velocity with inspiration (pulsed-wave Doppler)
- 40% increase in tricuspid inflow with inspiration
- Septal bounce or shift with respiration
Why Mitral Inflow Drops >25% With Inspiration
In tamponade, the pericardium cannot expand to accommodate increased venous return during inspiration. As RV filling increases, it pushes the interventricular septum leftward, reducing LV preload. This leads to a drop in mitral inflow velocity thus exaggerating normal respiratory variation. A >25% decrease in mitral E-wave velocity during inspiration supports tamponade physiology.
How to Measure
Use pulsed-wave Doppler at the mitral valve tips. Track changes in E-wave velocity across respiratory cycles - during inspiration (green line rises), mitral inflow should fall if tamponade physiology is present.
