What does RV afterload refer to?

RV afterload specifically refers to the pressure that the right ventricle must overcome to eject blood into the pulmonary artery during systole. This pressure is primarily determined by the pulmonary artery pressures, which include the mean pulmonary artery pressure and the pressures within the pulmonary circulation. When considering the right ventricle, it must generate enough force to move blood against the resistance presented by these pressures.

By understanding that RV afterload is closely related to the conditions of the pulmonary circulation, it becomes clear why pulmonary artery pressures are the defining factor of afterload for the right ventricle. In contrast, the other options relate to different aspects of cardiovascular physiology, such as systemic vascular resistance primarily influencing the left ventricle, or contractility which refers to the strength of the ventricular muscle contraction, rather than the pressure-load concept.