When is the blood volume in the right ventricle the lowest, allowing for the greatest volume of antegrade flow?

The blood volume in the right ventricle is at its lowest during early systole. This phase follows the diastolic filling of the heart when the right ventricle has received blood returning from the systemic circulation through the vena cavae. As the heart transitions into systole, the right ventricle begins to contract, leading to a decrease in volume as it ejects blood into the pulmonary artery.

During early systole, the tricuspid valve is closed, and the right ventricular muscle fibers are contracting. This phase optimally positions the heart to generate high pressure necessary for ventricular outflow, enhancing the flow of blood into the pulmonary circulation. The contraction reduces blood volume while ensuring that the blood flows forward efficiently, maximizing antegrade flow.

In contrast, during late diastole, the ventricle is filled with blood and at a maximum volume, which would not facilitate optimal antegrade flow. Mid systole occurs after the initial contraction when the volume may not be at its lowest point as the blood is still being ejected. During isovolumetric relaxation, the ventricle is also not at its lowest volume as it is transitioning back to diastole, preparing to fill again.

Thus, early systole is the point