Which feature of the LV PV loop indicates contractility?

• A. The width of PV loop.
• B. The slope of ESPVR reflects LV contractility (steeper means higher contractility).
• C. The slope of EDPVR reflects contractility.
• D. The area within PV loop reflects contractility.

Answer: (B)

Contractility is best indicated by the slope of the end-systolic pressure-volume relationship. This intrinsic property of the ventricle shows how much pressure it can generate at a given volume at end-systole. When contractility increases, the ventricle can achieve higher pressures with smaller end-systolic volumes, making the ESPVR steeper. Conversely, reduced contractility flattens this slope. The end-diastolic relation reflects diastolic compliance, not inotropic state, so its slope does not indicate contractility. The width of the loop relates to stroke volume, and the area inside the loop corresponds to stroke work, both of which are influenced by preload and afterload as well as contractility, but the ESPVR slope is the direct measure of contractility.