Afterload is most closely related to which factor?

Afterload is most closely related to which factor?

• A. Vascular resistance
• B. Preload
• C. Heart rate
• D. Contractility

Answer: (A)

The main concept being tested is that afterload is the pressure the ventricle must overcome to eject blood. In the systemic circulation this load comes from arterial pressure and the resistance the arteries offer—the vascular resistance. So afterload tracks closely with how much resistance the heart has to push against; higher vascular resistance (as in vasoconstriction or hypertension) raises afterload, while lower resistance lowers it. Preload is about venous return and end-diastolic filling, heart rate affects cardiac output but not the load the ventricle must overcome during ejection, and contractility is the intrinsic strength of contraction rather than the pressure the ventricle must overcome.

The main concept being tested is that afterload is the pressure the ventricle must overcome to eject blood. In the systemic circulation this load comes from arterial pressure and the resistance the arteries offer—the vascular resistance. So afterload tracks closely with how much resistance the heart has to push against; higher vascular resistance (as in vasoconstriction or hypertension) raises afterload, while lower resistance lowers it.

Preload is about venous return and end-diastolic filling, heart rate affects cardiac output but not the load the ventricle must overcome during ejection, and contractility is the intrinsic strength of contraction rather than the pressure the ventricle must overcome.