In cardiac sonography, what does the term "ejection fraction" measure?

Ejection fraction is a crucial measurement in cardiac sonography that quantifies how effectively the heart pumps blood. It is expressed as a percentage and represents the amount of blood that is ejected from the ventricles with each contraction compared to the total volume of blood present in the ventricles at the end of filling (diastole).

A healthy ejection fraction typically ranges from 55% to 70%, indicating that the heart is functioning well and efficiently pumping a significant portion of the blood with each beat. It is an essential parameter for assessing cardiac function and diagnosing various heart conditions, such as heart failure or cardiomyopathy.

The other choices refer to different aspects of cardiac function or anatomy, but they do not accurately define ejection fraction. The volume of blood in the heart at rest relates to preload but does not convey the efficiency of the heart's pumping action. The speed of blood flow is associated with hemodynamics and vessel resistance, not specifically with ejection fraction. The thickness of the heart walls pertains to myocardial hypertrophy or structural heart disease, rather than the function of blood ejection during a heartbeat.