Afterload is best described as which of the following?

• A. The resistance the left ventricle must overcome to eject blood
• B. The amount of blood in the ventricle at end-diastole
• C. The rate of impulse conduction through the AV node
• D. The venous return to the right atrium

Answer: (A)

Afterload is the pressure or resistance the left ventricle must overcome to eject blood during systole. It reflects the load the ventricle faces in pushing blood into the aorta, mainly the aortic pressure and systemic vascular resistance. When afterload increases, the ventricle must generate higher pressure to open the aortic valve, which can reduce stroke volume if contractility doesn’t rise and increase the heart’s workload and oxygen demand. Chronic high afterload—seen in conditions like hypertension or aortic stenosis—drives left ventricular hypertrophy as the heart adapts to the increased workload. By contrast, preload refers to the volume of blood in the ventricle at end-diastole, and venous return is part of preload; the rate of impulse conduction through the AV node describes conduction, not afterload.