Isovolumetric relaxation ends when which event occurs?

Isovolumetric relaxation ends when which event occurs?

• A. Isovolumetric relaxation ends when the mitral valve opens.
• B. Isovolumetric relaxation occurs during systole.
• C. Isovolumetric relaxation occurs after the aortic valve closes, with all valves closed and LV pressure falling; ends when the mitral valve opens.
• D. Isovolumetric relaxation ends when the aortic valve opens.

Answer: (C)

Isovolumetric relaxation is the early diastolic interval when the ventricle relaxes but all valves are closed, so the volume doesn’t change and LV pressure falls. It ends when the mitral valve opens, allowing filling to begin. This follows after the aortic valve has already closed, leaving both the aortic and mitral valves closed during relaxation. The mitral valve opening marks the transition out of isovolumetric relaxation into filling.

Isovolumetric relaxation is the early diastolic interval when the ventricle relaxes but all valves are closed, so the volume doesn’t change and LV pressure falls. It ends when the mitral valve opens, allowing filling to begin. This follows after the aortic valve has already closed, leaving both the aortic and mitral valves closed during relaxation. The mitral valve opening marks the transition out of isovolumetric relaxation into filling.