In cardiac tamponade, how do transvalvular pressure gradients change during expiration?

In cardiac tamponade, there is a characteristic reciprocal respiratory variation in transvalvular flow velocities due to ventricular interdependence and impaired cardiac filling. During expiration, the intrathoracic pressure increases, which leads to decreased right ventricular filling and thus decreased transtricuspid flow velocity. Simultaneously, left ventricular filling increases, causing an increase in transmitral flow velocity.

Therefore, during expiration, the transmitral gradient increases while the transtricuspid gradient decreases. This phenomenon reverses during inspiration, where transtricuspid flow increases and transmitral flow decreases. These respiratory variations are diagnostic hallmarks of tamponade physiology and help distinguish it from other conditions.

This principle is illustrated in Doppler echocardiographic studies of ventricular inflow and is described with diagrams in the "Textbook of Clinical Echocardiography, 6e" (Chapter 10: Pericardial Disease), highlighting the changes in transmitral and transtricuspid velocities during the respiratory cycle in tamponade .