Preload vs afterload: which concept corresponds to ventricular wall stretch at end of diastole?

Preload vs afterload: which concept corresponds to ventricular wall stretch at end of diastole?

• A. Preload is the ventricular wall stretch at the end of diastole (related to venous return and EDV); afterload is the pressure the ventricle must overcome to eject blood
• B. Preload is the pressure ventricle must overcome to eject blood; afterload is the end-diastolic stretch
• C. Preload is the end-systolic stretch; afterload is the pressure the ventricle must overcome to eject blood
• D. Preload is diastolic filling; afterload is systolic pressure

Answer: (A)

Preload is the ventricular wall stretch at the end of diastole, reflecting how much the ventricle is filled before it contracts. This stretch comes from venous return and the resulting end-diastolic volume, setting the initial sarcomere length and influencing stroke volume via the Frank-Starling mechanism. Afterload, by contrast, is the pressure the ventricle must overcome to eject blood—primarily the arterial pressure and systemic vascular resistance during systole. End-systolic stretch isn’t about the end of diastole, and diastolic filling describes the process of filling rather than the resulting stretch.

Preload is the ventricular wall stretch at the end of diastole, reflecting how much the ventricle is filled before it contracts. This stretch comes from venous return and the resulting end-diastolic volume, setting the initial sarcomere length and influencing stroke volume via the Frank-Starling mechanism. Afterload, by contrast, is the pressure the ventricle must overcome to eject blood—primarily the arterial pressure and systemic vascular resistance during systole. End-systolic stretch isn’t about the end of diastole, and diastolic filling describes the process of filling rather than the resulting stretch.