Afterload is defined as what?

• A. The force of ventricular contraction
• B. The heart rate
• C. The resistance to ventricular ejection of blood
• D. The amount of blood returning to the heart

Answer: (C)

Afterload is the resistance the ventricle must overcome to eject blood during systole. It is mostly determined by arterial pressure and systemic vascular resistance. When afterload is high, the ventricle has to generate more pressure to push blood out, which can lower stroke volume if contractility doesn’t compensate. This contrasts with preload, the amount of blood returning to the heart, and with contractility, the force of contraction itself. It’s also not the heart rate. Conditions like hypertension or aortic stenosis raise afterload, illustrating the concept.