What is afterload?

What is afterload?

• A. The resistance to ventricular ejection, determined by systemic vascular resistance (SVR) and pulmonary vascular resistance (PVR).
• B. The amount of venous return to the heart per minute.
• C. The intrinsic contractile strength of the myocardium.
• D. The heart rate during activity.

Answer: (A)

Afterload is the pressure or resistance the ventricle must overcome to eject blood during systole. For the left ventricle this means pushing blood against systemic vascular resistance and arterial pressure; for the right ventricle, against pulmonary vascular resistance and pulmonary arterial pressure. When afterload rises, the ventricle must generate higher pressure to open the valve, which can reduce stroke volume and cardiac output if contractility can’t compensate. This is different from preload (venous return filling the ventricle), contractility (the myocardium’s intrinsic contraction strength), and heart rate (beats per minute).

Afterload is the pressure or resistance the ventricle must overcome to eject blood during systole. For the left ventricle this means pushing blood against systemic vascular resistance and arterial pressure; for the right ventricle, against pulmonary vascular resistance and pulmonary arterial pressure. When afterload rises, the ventricle must generate higher pressure to open the valve, which can reduce stroke volume and cardiac output if contractility can’t compensate. This is different from preload (venous return filling the ventricle), contractility (the myocardium’s intrinsic contraction strength), and heart rate (beats per minute).