Which characteristic sign most commonly accompanies right atrial collapse in cardiac tamponade?

Right atrial collapse in cardiac tamponade is most commonly associated with a large pericardial effusion. In the context of cardiac tamponade, fluid accumulates in the pericardial space, exerting pressure on the heart and particularly affecting the chambers of the heart when they attempt to fill during diastole. When there is a significant amount of fluid, the pressure from the outside can cause the right atrium to become compressed, leading to collapses during diastolic filling.

This mechanism is why a large pericardial effusion is a characteristic find in cases of cardiac tamponade. The presence of excessive fluid allows for the conditions conducive to this collapse to occur, as it impedes normal heart function and blood flow.

Other options reflect different aspects of hemodynamics and fluid status that may or may not be present in a patient with cardiac tamponade, but they do not directly describe the specific phenomenon of right atrial collapse linked to large volumes of effusion.