What would you expect if EDV rises beyond the Frank-Starling plateau?

• A. SV continues to rise linearly.
• B. SV plateaus or declines.
• C. SV becomes highly erratic.
• D. SV is unaffected by EDV.

Answer: (B)

Beyond the plateau, increasing end-diastolic volume no longer boosts how much blood the ventricle can eject. The Frank-Starling curve shows that SV rises with preload only up to a point; after that, further stretching of the cardiac fibers reduces the effectiveness of contraction, so stroke volume levels off and can even decline. In short, extra EDV leads to a plateau or a fall in SV.