What occurs to the hemodynamic state of the right atrium in late diastole due to cardiac tamponade?

In late diastole during cardiac tamponade, the hemodynamic state of the right atrium collapses due to the increased pressure in the pericardial space. Cardiac tamponade is characterized by the accumulation of fluid in the pericardial sac, which restricts the filling of the heart chambers, particularly during diastole when the heart is at rest and filling with blood. As the volume of fluid increases, the pressure in the pericardial space exceeds the pressure in the heart chambers, including the right atrium.

This pressure difference leads to the collapse of the right atrial walls, especially during late diastole when the atrium is under the most stress to accept incoming blood from the systemic circulation. The decreased right atrial filling results in a reduction in stroke volume and can lead to significant hemodynamic instability. Understanding this process emphasizes the importance of monitoring hemodynamics in patients suspected of having cardiac tamponade.

The other options—expansion, stabilization, or hypertrophy of the right atrium—do not occur in this scenario due to the constraining effects of the elevated pericardial pressure.