What does the term 'ejection fraction' measure?

Ejection fraction is a crucial measurement in cardiology that assesses the efficiency of the heart’s pumping ability. Specifically, it refers to the percentage of blood that is ejected from the left ventricle during each contraction relative to the total volume of blood in the ventricle before contraction. Therefore, the correct answer highlights that ejection fraction is expressed as a percentage, demonstrating how much blood is effectively pushed out of the heart with each heartbeat compared to the volume present before the heart contracts.

This measurement is vital for evaluating heart function; a normal ejection fraction typically ranges from 55% to 70%. Deviation from this range can indicate cardiac issues, with reduced ejection fractions often seen in conditions like heart failure or cardiomyopathy. The other options pertain to different aspects of cardiac function but do not accurately define ejection fraction.