Which feature of the PV loop reflects LV compliance?

• A. The slope of ESPVR reflects LV compliance.
• B. End-diastolic volume reflects LV compliance.
• C. The slope of EDPVR reflects LV compliance (steeper means stiffer).
• D. The width of the PV loop reflects LV compliance.

Answer: (C)

Compliance is about how much the ventricle fills for a given filling pressure. On a pressure-volume loop, this shows up in the end-diastolic pressure-volume relationship. The slope of that curve tells you how pressure rises as volume increases during diastole. A steeper slope means pressure climbs quickly for small volume increases, indicating a stiffer ventricle with lower compliance. So the slope of the end-diastolic pressure-volume relationship is the best reflection of LV compliance.

The other features don’t measure compliance as directly: the end-systolic slope (ESPVR) mainly reflects contractility; end-diastolic volume depends on preload, not the heart’s passive stiffness; and the loop width reflects stroke volume, not diastolic filling compliance.